第十二篇






康熙教子庭训格言
（四）
礼用和贵 齐家治国
训曰：有子曰：「礼之用，和为贵。先王之道，斯为美。小大由之，有所不行。知和而和，不以礼节之，亦不可行也。」盖礼以严分，而和以通情分。严则尊卑贵贱不逾，情通则是非利害易达。齐家治国平天下，何一不由于斯？
名实相副　混淆不得
训曰：人之才行当辨其大小。在大位者，称其清廉可矣。若使役人等亦可加以清廉之名乎？朕曾于护军骁骑中问其人如何，而侍卫有以端密对者，军卒人等岂堪当此？端密乃居大位之美称，军卒止可言其朴实耳！
敬畏之心 不可不存
训曰：人生于世，无论老少，虽一时一刻不可不存敬畏之心。故孔子曰：「君子畏天命，畏大人，畏圣人之言。」我等平日凡事能敬畏于长上，则不罪于朋侪，则不召过，且于养身亦大有益。尝见高年有寿者，平日俱极敬慎，即于饮食，亦不敢过度。平日居处尚且如是，遇事可知其慎重也。
天道好生　仁爱为本
训曰：天道好生。人一心行善，则福履自至。观我朝及古行兵之王公大臣，内中颇有建立功业而行军时曾多杀人者，其子孙必不昌盛，渐至衰败。由是观之，仁者诚为人之本欤！
食宜淡薄　于身有益
训曰：朕每岁巡行临幸处，居人各进本地所产菜蔬，尝喜食之。高年人饮食宜淡薄，每兼菜蔬食之，则少病，于身有益。所以农夫身体强壮，至老犹健者，皆此故也。
酒伤身心 能饮不饮
训曰：朕自幼不喜饮酒，然能饮而不饮，平日膳后或遇年节筵宴之日，止小杯一杯。人有点酒不闻者，是天性不能饮也。如朕之能饮而不饮，始为诚不饮者。大抵嗜酒则心志为其所乱而昏昧，或至疾病，实非有益于人之物。故夏先君以旨酒为深戒也。
胸中正则眸子瞭焉，胸中不正则眸子眊焉
训曰：孟子云：「存乎人者，莫良于眸子。眸子不能掩其恶。胸中正则眸子瞭焉，胸中不正则眸子眊焉。」此诚然也。看来，人之善恶系于目者甚显，非止眸子之明暗有人焉，其视人也常有一种彷徨不定之态，则其人必不正。我朝满洲耆旧，亦甚贱此等人。
目容端 不回顾
训曰：凡人行住坐卧，不可回顾斜视。《论语》曰：「车中不内顾。」《礼》曰：「目容端。」所谓内顾，即回顾也。不端，即斜视也。此等处，不但关于德容，亦且有犯忌讳。我朝先辈老人，亦以行走回顾之人为大忌讳，时常言之，以为戒也。
心志专一　即是养生
训曰：人果专心于一艺一技，则心不外驰，于身有益。朕所及明季人与我国之耆旧善于书法者，俱寿考而身强健。复有能画汉人或造器物匠役，其巧绝于人者，皆寿至七八十，身体强健，画作如常。由是观之，凡人之心志有所专，即是养身之道。
居家洁净　清气著身
训曰：尔等凡居家在外，惟宜洁净。人平日洁净，则清气著身。若近污秽，则为浊气所染，而清时之气渐为所蒙蔽矣。
俭约不贪　福寿长全
训曰：民生本务在勤，勤则不匮。……是勤可以免饥寒也。至于人生衣食财禄，皆有定数。若俭约不贪，则可以养福，亦可以致寿。若夫为官者，俭则可以养廉。居官居乡只廉不俭，宅舍欲美，妻妾欲奉，仆隶欲多，交游欲广，不贪何以给之？与其寡廉，孰如寡欲？语云：「俭以成廉，侈以成贪。」此乃理之必然矣！
本文摘编自中国社会科学出版社 出版的 《康熙教子庭训格言》唐汉 译注 收起阅读 »

第九篇






康熙教子庭训格言
康熙一生兢兢业业，修身、齐家、平天下都十分认真，可谓耗尽心血和精力。康熙治国六十年建树甚多，其创业、守成之功绩举世公认。他十分珍惜自己的事业,渴望能传之千秋万代，自信生命中的每一体会对后人都有益处。
康熙曾对诸官说：「朕经常想到祖先托付的重任。对皇子的教育及早抓起，不敢忽视怠慢。天未亮即起来，亲自检查督促课业，东宫太子及诸皇子，排列次序上殿，一一背诵经书，至于日偏西时，还令其习字、习射，复讲至于深夜。自春开始,直到岁末，没有旷日。」
康熙教子的种种做法，法国传教士白晋以亲身见闻，向法国皇帝路易十四作了如实报告。白晋在报告中说：中国皇上以父爱的模范施以皇子教育，令人敬佩。中国的皇上特别注意对皇子们施以道德教育，努力进行与他们身份相称的各种训练，教之以经史、诗文、书画、音乐、几何、天文、骑射、游泳、火器等等。
教诲督促，严格训饬。康熙身后的儿孙们，多数能文能武，尤其在他之后的两个杰出帝王：雍正皇帝，功业显赫，见识超人；乾隆皇帝，儒雅倜傥，自号「十全皇帝」。正是「康熙盛世」的基础，奠定了满清王朝二百多年的业绩。所有这些，都是受到了康熙皇帝的道德遗泽和他的《庭训格言》　—— 一本珍藏的皇家遗嘱读本的影响。
在此，特摘录一些以飨读者：
庭训格言(一)
心欲小而胆欲大
训曰：凡人于无事之时，常如有事而防范其未然，则自然事不生。若有事之时，却如无事，以定其虑，则其事亦自然消失矣。古人云：「心欲小而胆欲大。」遇事当如此处也。
朕从不敢轻量人 谓其无知 言合乎理 朕即嘉纳
训曰：今天下承平，朕犹时刻不倦勤修政事。前三孽作乱时，因朕主见专诚，以致成功。惟大兵永兴被困之际，至信息不通，朕心忧之，现于词色。一日，议政王大臣入内议军旅事，奏毕佥出，有都统毕立克图独留，向朕云：「臣观陛下近日天颜稍有忧色。上试思之，我朝满洲兵将若五百人合队，谁能抵敌？不日永兴之师捷音必至。陛下独不观太祖、太宗乎？为军旅之事，臣未见眉颦一次。皇上若如此,则懦怯不及祖宗矣。何必以此为忧也。」朕甚是之。不日，永兴捷音果至。所以，朕从不敢轻量人，谓其无知。凡人各有识见。常与诸大臣言，但有所知、所见，即以奏闻，言合乎理，朕即嘉纳。都统毕立克图汉仗好，且极其诚实人也。
大凡能自任过者 大人居多也
训曰：凡人孰能无过？但人有过，多不自任为过。朕则不然。于闲言中偶有遗忘而误怪他人者，必自任其过，而曰：「此朕之误也。」惟其如此，使令人等竟至为所感动而自觉不安者有之。大凡能自任过者，大人居多也。
审之又审 方无遗虑
训曰：凡人于事务之来，无论大小，必审之又审，方无遗虑。故孔子云：「不曰如之何、如之何者，吾末如之何也已矣。」诚至言也！
敬以直内 谨终如始
训曰：凡天下事不可轻忽，虽至微至易者，皆当以慎重处之。慎重者，敬也。当无事时，敬以自持；而有事时，即敬之以应事物；必谨终如始，慎修思永，习而安焉，自无废事。盖敬以存心，则心体湛然。居中，即如主人在家，自能整饬家务，此古人所谓敬以直内也。《礼记》篇首以「毋不敬」冠之，圣人一言，至理备焉。
以德服人者 中心悦而诚服也
训曰：王师之平蜀也，大破逆贼王平藩于保宁，获苗人三千，皆释而归之。及进兵滇中，吴世璠穷蹙，遣苗人济师以拒我。苗不肯行，曰:「天朝活我恩德至厚，我安忍以兵刃相加遗耶？」夫苗之犷猂，不可以礼义驯束，宜若天性然者。一旦感恩怀德，不忍轻倍主上，有内地士民所未易能者，而苗顾能之，是可取之。子舆氏不云乎：「以力服人者，非心服也，力不赡也；以德服人者，中心悦而诚服也。」宁谓苗异乎人而不可以德服也耶？
仁者以万物为一体 恻隐之心触处发现
训曰：仁者以万物为一体，恻隐之心，触处发现。故极其量，则民胞物与，无所不周。而语其心，则慈祥恺悌，随感而应。凡有利于人者，则为之；凡有不利于人者，则去之。事无大小，心自无穷，尽我心力，随分各得也。
欢喜善念吉 动怒恶念凶
训曰：凡人处世，惟当常寻欢喜。欢喜处自有一番吉祥景象。盖喜则动善念，怒则动恶念。是故古语云：「人生一善念，善虽未为，而吉神已随之；人生一恶念，恶虽未为，而凶神已随之。」此诚至理也夫！
俯仰无愧 防于念起
训曰：人惟一心，起为念虑。念虑之正与不正，只在顷刻之间。若一念不正，顷刻而知之，即从而正之，自不至离道之远。《书》曰：「惟圣罔念作狂，惟狂克念作圣。」一念之微，静以存之，动则察之，必使俯仰无愧，方是实在工夫。是故古人治心，防于念之初生、情之未起，所以用力甚微而收功甚巨也。
本文摘编自中国社会科学出版社 出版的 《康熙教子庭训格言》唐汉 译注 收起阅读 »

第六篇






修福积福造命法
——明·袁了凡
立命：
※ 凡人所以不得作圣者，只为妄念相缠耳。
※ 命由我作，福自己求。
※ 一切福田，不离方寸，从心而觅，感无不通，求在我，不独得道德仁义，亦
得功名富贵，内外双得，是求有益于得也，若不反躬内省，而徒向外驰求，则求之有道，而得之有命矣，内外双失，故无益。
※ 即如生子，有百世之德者，定有百世子孙保之，有十世之德者，定有十世子
孙保之，有三世二世之德者，定有三世二世子孙保之，其斩焉无后者，德至薄也。
※ 万缘放下，一尘不起。
※ 修身以俟之，曰修，则身有过恶，皆当治而去之。日俟，则一毫觊觎，一毫
将迎，皆当斩绝之矣。
※ 远思扬祖宗之德，近思盖父母之愆，上思报国之恩，下思造家之福，外思济
人之急，内思闲己之邪。
※ 务要日日知非，日日改过，一日不知非，即一日安于自是，一日无过可改，
即一日无步可进。
※ 天下聪明俊秀不少，所以德不加修，业不加广者，只为因循二字，耽阁一
生。
改过：
※ 吉凶之兆，萌乎心而动乎四体，其过于厚者常获福，过于薄者常近祸。
※ 至诚合天，福之将至，观其善而必先知之矣，祸之将至，观其不善而必先知
之矣。
※ 闲居之地，指视昭然，吾虽掩之甚密，文之甚巧，而肺肝早露，终难自欺，
被人觑破，不值一文矣。
※ 尘世无常，肉身易殒。一息不属，俗改无由矣。
※ 行有不得，皆己之德未修，感未至也，吾悉以自反。
※ 过有千端，惟心所造，吾心不动，过安从生。
※ 一心为善，正念现前，邪念自然污染不上。
※ 最上者治心，当下清净，才动即觉，觉之即无。
※ 发愿改过，明须良朋提醒，幽须鬼神证明，一心忏悔，昼夜不懈，必有效验。
积善：
※ 积善之家，必有余庆。
※ 遇有横逆，辄反躬自责，怡然顺受。
※ 有益于人是善，有益于己是恶。
※ 利人者公，公则为真。利己者私，私则为假。又根心者真，袭迹者假。
※ 凡欲积善，绝不可徇耳目，惟从心源隐微处，默默洗涤。
※ 纯是济世之心则为端，苟有一毫媚世之心即为曲。纯是爱人之心则为端，有
一毫愤世之心即为曲，纯是敬人之心则为端，有一毫玩世之心即为曲。
※ 阴德天报之，阳善享世名，名亦福也，名者造物所忌，世之享盛名而实不副
者，多有奇祸，人之无过咎而横被恶名者，子孙往往骤发，人之为善，不论现行，而论流弊，不论一时，而论久远，不论一身，而论天下。
※ 为善而心不着善，则随所成就皆得圆满，心着于善，虽终身勤励，止于半善
而已。
※ 譬如以财济人，内不见己，外不见人，中不见所施之物，是谓三轮体空，是
谓一心清净，则斗粟可以种无涯之福，一文可以消千劫之罪，倘此心未忘，虽黄金万镒，福不满也。
※ 克己须从难克处克将去，夫子论为仁，亦曰先难，所谓难舍处能舍也，难忍
处能忍也，故天降之福亦厚。
※ 随缘济众。
※ 与人为善，爱敬存心，成人之美，劝人为善，救人危急，兴建大利，舍财作
福，护持正法，敬重尊长，爱惜物命。
※ 不以言教，而以身转之，此良工苦心也，吾辈处末世，勿以己之长而盖人，
勿以己之善而形人，勿以己之多能而困人，收敛才智，若无若虚。
※ 凡日用间，发一言，行一事，全不为自己起念，全是为物立则，此大人天下
为公之度也。
※ 君子所以异于人者，以其存心也，君子所存之心，只是爱人敬人之心，盖人
有亲疏贵贱，有智愚贤不肖，万品不齐，皆吾同胞，皆吾一体，孰非当敬爱者，爱敬众人，即是爱敬圣贤，能通众人之志，即是通圣贤之志，圣贤之志，本欲斯世斯人，各得其所，吾合爱合敬，而安一世之人。
※ 所谓布施者，只是舍之一字耳，内舍六根，外舍六尘，一切所有，无不舍
者，内以破吾之悭，外以济人之急，始而勉强，终则泰然，最可以荡涤私情，祛除执吝。
※ 在家奉侍父母，使深爱婉容，柔声下气，习以成性，便是和气格天之本。
※ 事君如天，此等处，最关阴德。
※ 闻杀不食，见杀不食，自养者不食，专为我杀者不食。
※ 蠢动含灵，皆为物命，求丝煮茧，锄地杀虫，念衣食之由来，皆杀彼以自活。
※ 暴殄之孽，当与杀生等。
谦德：
※ 天道亏盈而益谦，地道变盈而流谦，鬼神害盈而福谦，人道恶盈而好谦，谦
之一卦，六爻皆吉。
※ 满招损，谦受益，惟谦受福。
※ 天将发斯人也，未发其福，先发其慧，此慧一发，则浮者自实，肆者自敛，
建所温良若此，天启之矣。
※ 造命者天，立命者我，力行善事，广积阴德，何福不可求哉。
※ 善事阴功，皆由心造，常存此心，功德无量，譬如谦虚一节，并不费钱。
※ 彼气盈者，必非远器，纵发亦无受用，稍有识见之士，必不忍自狭其量，而
自拒其福也。
※ 谦则受教有地，而取善无穷，尤修业者，所必不可少者也。
※ 人之有志，如树之有根，立定此志，须念念谦虚，尘尘方便，自然感动天地,
而造福由我。 收起阅读 »

各位，7月1日已過，各廠商也在積極應對，但是據我所知，不但是我司很多公司在追溯上都存在問題，一旦出問題不能最終追溯到供應商。就拿我公司來説吧，對於同種型號產品存在兩家或兩家以上的供應商，一旦材料同時上線，就很難再追到供應商了，

　　
同情。。。。转子新浪
一. 　　我的初恋女友初恋时19岁. 　　我的现任女友初恋时16岁. 　　 　　二. 　　我的初恋女友是我的大学同学. 　　我的现任女友是我在泡吧时认识的. 　　 　　三. 　　我连哄带骗花半个月后与我初恋女友发生了关系. 　　我与现任女友认识的当天就在一起. 　　 　　四. 　　我和初恋女友发生关系的地点在我们宿舍. 　　我和现任女友在四星的酒店开房. 　　 　　五. 　　第一次和初恋女友约会.吃的是二块钱一碗的刀削面.她说吃不了还夹了一大半给我. 　　第一次和现任女友约会,吃的是八十八元一份的西式牛排.完了她还要了一份水果沙拉. 　　 　　六. 　　第一次走路送初恋女友回家,她神采飞扬.笑个不停 　　第一次走路送现任女友回家,她说我小气,怎么不打的. 　　 　　七. 　　送初恋女友一个"史卢比"她高兴好几天,不停得向她室友炫耀. 　　送现任女友一个铂金戒子.她看了两眼,放近抽屉.原来是嫌它小了. 　　 　　八. 　　初恋女友买衣服时,逛的大型批发市场 　　现任女友买衣服时,逛的是品牌专卖店 　　 　　九. 　　与初恋女友吵架,她边抽泣边小声问到:"你不爱我了吗?" 　　与现任女友吵架,她坐在沙发上指着我骂道:"你们男人没一个好东西" 　　 　　十. 　　与初恋女友在一起时,她把家里每个月寄给她的生活费存到我的食堂饭卡上. 　　与现任女友在一起时,我每个月的工资存到她的存折上. 　　 　　十一. 　　与初恋女友在一起,早上我醒来时候,她已经买好了早餐等我起来吃. 　　与现任女友在一起,她躺在床上对我说:"老公,我饿!去给我买早餐." 　　 　　十二. 　　初恋女友下课后在我教室门口等我一起去食堂吃饭.甚至有时打了饭送来给我吃. 　　现在我经常下班了回来买菜做饭等现任女友回来吃.甚至有时还得给她送过去. 　　 　　十三. 　　初恋女友经常坐在我身边陪我上网到天亮,最后她伏在桌子上睡着了. 　　现任女友经常打麻将打天亮 ,我坐在旁边看着,最后我坐在凳子上睡着了. 　　 　　十四. 　　初恋女友听见我和死党们说黄色笑话会脸红. 　　现任女友经常把她手机里的黄色短信转发给我. 　　 　　十五. 　　初恋女友听我说在家里面总是头疼，还感觉呼吸难受。就说那是我懒，天天去帮我开窗户放空气，还给我 　　 　　打扫卫生。 　　现任女友听说后鄙视的看了我一眼，说这叫室内污染，这个都不懂？然后随手扔过来一瓶“天下无贼健康 钛”，说，回去喷一遍，这是最新的治理室内污染的产品，我用过了，很管用的。 　　 　　十六. 　　第一次牵我初恋女友的手,她的手心在冒汗.呆呆的她任由我牵着（准确说应该是任由我拖着） 　　第一次牵我现任女友的手,她自然的把手指反扣过来,牵着我 　　 　　 　　请大家看完后留下感受:是觉得好笑还是觉得难受. 　　谢谢各位支持，希望大家珍惜和尊重现在你所拥有的感情。 收起阅读 »

去年的肯德基里面有苏丹红一号.
今年的鸡蛋黄里面有苏丹红四号.
前阵子知道奶瓶就是碎光盘用硫酸清洗后再熔的.
昨天又知道太太乐鸡精不能吃.
每次有新闻出现,总会有一些专家学者出来告诉人们,这些东西应该怎样分辨,什么是好什么是不好,要多留个心眼.
我只是一名普通老百姓,去趟超市我究竟需要掌握多少种分辨真伪的方法?
我需要长多少个心眼才能不被他们黑到? 收起阅读 »

呵呵`终于开通了`

版权属于作者



评定封装可靠性水平的MSL试验


劳鸿章


(上海贝岭股份有限公司，上海 200233)


摘要：随着塑料封装集成电路在众多领域中的广泛应用，封装的质量和可靠性水平越来越受到广大用户的关注。作为评定和考核封装可靠性水平的重要特征参数，除通常采用的环境试验如Autoclave(PCT)、HAST Bias、TH Bias外，MSL(Moisture Sensitivity Level)试验已成为其中最重要的试验项目之一。
关键词：回流敏感度分级；模塑料；分层
中图分类号：TN306 文献标识码：A 文章编号：1681-1070(2005)05-22-04
1 前言
集成电路的塑料封装由于成本低、质量好、易自动化、批量大生产，在国内外早已形成工业化大生产的格局。近一时期，随着笔记本电脑、摄录机、手机等重量的减轻，带来与这些配套的集成电路和元器件更小型化和微型化的趋势。这必然促使对电子元器件的封装要求越来越小和越来越薄。如32脚薄型的QFN(Quad Flat No Lead)塑料封装长×宽×高尺寸只有5mm×5mm×0．8mm，脚与脚间距为0．5mm。
由于对封装要求的提高，必然需要相应的封装设备、封装材料和受控的封装工艺生产线来加以保证，尤其对塑料封装的抗潮性能将会提出更高的要求。
因为封装的模塑料是改性环氧塑料，它属于热塑性、线型性的高分子树脂，并且它本身具有吸湿和透湿两重性，所以封装的优劣将导致成品对水气敏感或不敏感，以致直接影响和降低成品的抗潮性能。2 模塑料与水的敏感程度
下面的实验数据充分说明模塑料的抗潮性能。表1和图1列出不同模塑料在标准大气条件和一定时间内的吸湿数据。从吸湿的结果来看，模塑料1的抗潮性比模塑料2好，而模塑料2的抗潮性比模塑料3好。











图2为不同的模塑料(不同的封装形式)在121℃／100％RH／15：Psig的潮气中的吸湿状况和其吸湿达到饱和所需要的时间。从模塑料的材料来看，模塑料4的抗潮性优于模塑料1，而模塑料1的抗潮性则优于模塑料3；从材料吸湿达到饱和的时间来看，TSSOP8封装的抗潮性劣于SOIC8封装，而SOIC8封装的抗潮性则劣于SMD8封装。
3 MSL试验
(1)试验目的
鉴别非气密性固态表面贴装器件对潮气产生的应力的敏感度分级，使塑料封装产品可以被正确地包装、贮存和搬运，以免其在回流焊贴装和／或修理操作中引起损伤。
(2)适用范围
适用于非气密性固态表面贴装器件。
(3)试验流程(见图3)





(4)潮气敏感度级别(见表2)





(5)回流焊接的峰值温度的条件(见表3)





(6)试验样品的数量
有可靠性试验评估的：11个／每个级别；没有可靠性试验评估的：22个／每个级别。(7)失效标准
在试验样品中，如一个或大于一个失效，这种封装形式将被认为预定的试验级别失效。若存在下例任一情况，则认为样品失效：
·在40倍光学显微镜下看到外部开裂；·电性能测试失效；·贯穿一焊接的金丝、金球压点或楔形压点的内部开裂；·内部开裂延伸从任意引线脚到其他内部的界面(引线脚、芯片、芯片托板)；·内部开裂延伸从任意内部的界面到塑封体的外部大于2／3的长度；·通过裸视，明显的看到塑封体平面的变化是由于翘曲、肿胀或膨胀，如样品仍然满足共平面和下沉尺寸的话，可认为通过。
(8)需要进一步评估的标准 评价分层对于器件可靠性的影响，半导体制造商可以按分层的要求、JEsD22-A113和JESD47或半导体制造商的内部程序文件执行可靠性评估试验。分层测试是指从潮湿前到回流后，回流前后之间分层变化的值。它所计算的是分层占有关联的总区域的百分比的变化值。可靠性评估可以由应力试验、历史的一般数据分析等组成。如果表面贴装的器件能通过电性能测试，即使在芯片托板、散热器、芯片背面(仅限于芯片上引线)上有分层，但是没有开裂或其他的分层，可以认为它们仍满足规定分层的标准，同时被认为通过潮气灵敏度级别。
(9)金属框架封装的分层的失效标准：·在芯片的有源区域没有分层；·任何芯片托板的接地区域金丝球焊表面或芯片上引线的器件的分层不大于10％；·延着任何起隔离作用的聚合膜跨越任何金属界面的分层不大于10％；·在高热特性封装中通过芯片粘接区域或需要电接触到芯片背面的器件，分层／开裂不大于10％；·没有分层超过它的整个长度的表面破裂界面(一个表面破裂的界面包括引线脚、tie bars、散热器、热芯块等)。
(10)失效标准
所有失效必须分析并确认该失效机理是否与潮气敏感度有关联。如果在选择的级别中，失效不是起因于回流潮气敏感度，则认为这器件仍通过相应的潮气敏感度级别。(11)可靠性评估试验的项目／条件和判据
对于预定的MSL级别，先进行MSL的预处理试验(除了MSL流程图中的第2、4、6、9步)。预处理试验后，建议做以下两项可靠性评估试验(试验样品的数量和合格判决可参考JESD47中的试验方案)。
·168小时#121℃100％RH 15Psig PCT测试。
·100次循环#一65-150℃T／C测试。
(12)潮气／回流敏感度分级
·若某一封装通过了MSL 1级，则认为该封装对潮气是不敏感的。出货时，不必采用干包装。
·若某一封装没有通过MSL 1级，但通过了2～5级中的某一级，则认为该封装对潮气是敏感的，可以按照J-STD-033的要求，出货时必须采用干包装。
·若某一封装仅通过MSL 6级，则认为该封装对潮气是非常敏感的，只用干包装是不够的。出货时，应通知客户该封装的MSL级别。同时，提供该封装的解吸曲线。
(13)吸收和解吸曲线
该曲线应由封装厂提供。
(14)参考标准
请参考J-STD 020B。
4 结论
根据非气密性的SMD(Surface Mount Device)产品的MSL试验级别，能获得该产品的封装可靠性水平，可以监督和促使封装厂家改进封装质量，从而保证公司产品的质量信誉；对潮气敏感的SMD产品，可以采用干包装提供给客户。对潮气非常敏感的SMD产品，在发货时可以通知客户其产品的MSL试验级别，以便客户对该产品采取烘烤的措施(具体的温度和时间取决于封装厂家提供的该封装的解析曲线)，从而避免SMD产品在表面贴装时，发生爆米花或其他缺陷；大多数集成电路制造厂已将MSL试验作为对封装厂家工程认定的关键项目之一。


本文摘自《电子与封装》 收起阅读 »

一般每个人都有自己做事的原则，底线。你是一直坚持到现在呢，还是曾经破过一/二次。是因为什么破呢，被迫？钱？情？ 在你心里，底线已破就不称之为底线了吗？

Cpk or Ppk: Which should you use?Your customer has asked you to report the Cpk of the product you are sending. You know that to compute the Cpk, you need to have the product specifications, and that you need to have the mean and sigma. As you gather the information, someone asks, "which sigma do they want?"You know that Cpk is calculated by dividing by 3 sigma. But which sigma should you use, estimated or calculated? Which is correct? Which would you report? Naturally, most of us would use the sigma that makes the Cpk look the best. But the sigma that makes the Cpk look best may not accurately reflect what you or your customer need to know about the process.Confusion over calculating Cpk by two different methods is one reason that a new index, Ppk, was developed. Ppk uses the calculated sigma from the individual data. Ppk=Zmin/3whereZmin=smaller of the Zupper , ZlowerZupper=(USL-Xbar-bar)/sigma1Zlower=(Xbar-bar-LSL)/sigma1Sigma of the individuals:sigma1square= ((Xi-Xbar)square/n-1) Given that Ppk uses the calculated sigma, it is no longer necessary to use the calculated sigma in Cpk. The only acceptable formula for Cpk uses the estimated sigma.Cpk=Zmin/3whereZmin=smaller of the Zupper,ZlowerZupper=(USL-Xbar-bar)/sigma2Zlower=(Xbar-bar-LSL)/sigma2Estimated sigma:sigma2=Rbar/D2Given that Ppk uses the calculated sigma, it is no longer necessary to use the calculated sigma in Cpk. The only acceptable formula for Cpk uses the estimated sigma.In 1991, the ASQC/AIAG Task Force published the "Fundamental Statistical Process Control" reference manual, which shows the calculations for Cpk as well as Ppk. These should be used to eliminate confusion about calculating Cpk.So which value is best to report, Cpk or Ppk? Although they show similar information, they have slightly different uses.Estimated sigma and the related capability indices (Cp, Cpk, and Cr) are used to measure the potential capability of a system to meet customer needs. Use it when you want to analyze a system's aptitude to perform.Actual or calculated sigma (sigma of the individuals) and the related indices (pp, Ppk, and Pr) are used to measure the performance of a system to meet customer needs. Use it when you want to measure a system's actual process performance.please speak out your ideas about this mind, thank you .Mail:river.xu#mic.com.tw 收起阅读 »

　怀念是一种幸福的痛，是心里难舍的情节，许多过往，不曾仔细咀嚼，便匆匆而去，象投入河里的一颗石子，悄无声息的隐藏在心理深处。有许多往事，不曾触及，象似遗忘，其实已深入骨髓，看似平淡，其实内心的情感不时的会蜂拥而至，只是怕人看见，只好让那缤纷的思绪放纵的占据心头。　 　　时光已逝去多年，但生活依然，只有那静静的河水在缓缓地诉说着曾经的怀念，现早已物是人非，可风依旧在吹，带着醉心的温柔和迷人的娇羞，让人有点惆怅，有点哀伤，有点迷醉，又有点遐想。 　　红尘漫漫，往事如烟，还记得故乡的小河装载的童年，每每回家，总会伫立河畔良久，不忍离去，仿佛仍能听见儿时的嬉笑，还有母亲的责备和呼唤，不知那条从手中滑落的草鱼，是早已成了别人的美餐，还是在守着孩子们的幸福中，平静的老去。　 　　那曾划破我脚丫的铁钉，是否已被时间锈蚀的不知去向，心有境生，淡淡的忧伤，浅浅的哀愁，构成了我的一段人生。　 　　那是一段穷苦的日子，生活的拮据也难以掩饰我对快乐的追逐与渴求。无法忘记的是一个大雪纷飞的午后，母亲步行几里路给我送衣服的情景，当她离去时，我无发表达的激动与感伤，只有任凭漫天的雪花拂去母亲蹒跚的脚印。　 　　我为母亲感到悲哀，因为她连自己的名字都无法写出，她的世界会不会很枯燥无味，但又为她感到欣慰，因为她拥有我们的世界，包容了我们的精彩　 　　世界也许只有昨天与明天的界限，而今天短暂的难以分辨，做已是往昔，不做就是未来，于是渴望与怀念就成了永恒的主题。 收起阅读 »

“将一只青蛙扔进沸水里，它会立刻弹跳出来，得以逃生；当将这只青蛙放在冷水里，慢慢加热，则它会在逐渐升温的水里舒适惬意地游来游去，渐渐失去生命力，最终被活活地煮死……” 　　从建国初轰动全国的“刘青山张子善贪污案”，到近些年查处的　“红塔集团褚时建”“河北第一秘”“深圳第一贪”……无不让人痛恨惋惜，他们有的穿过枪林弹雨，经历血雨腥风，抛过头颅，洒过热血，为共和国立下汗马功劳；有的大胆改革，励精图治，挽救企业于危难之时，为单位为国家做出巨大贡献；有的年轻有为，工作出色，被称为“楷模”“典范”……艰难险阻没能扼杀其抗争的勇气，危难时刻没能磨蚀其顽强的生命力，他们却在歌舞升平的悠闲自在中逐渐迷失自我，在改革开放的灯红酒绿中越陷越深，无法自拔，最终丢失传统，丧失党性，成为国家和人民的公敌，也成为“温水煮青蛙效应”有力佐证。 　　防止蜕化，预防变质，应防微杜渐，未雨绸缪　！《后汉书。丁鸿传》说“若敕政责躬，杜渐防萌，则凶妖销灭，害除福凑矣。”党员干部往往一开始都是优秀的，不乏大量的出类拔萃者，有的政绩卓著，工作勤恳；有的大胆改革，勇于创新；有的一心为民，兢兢业业。而他们的的腐败往往都是从小事开始的，小礼物，纪念品，小礼金，逐步升级，一步步下滑，一步步沦落，最终欲望似洪水，一发不可收拾，当意识到问题的严重性时，已经积重难返，无法自拔，就像“温水中的青蛙”一样，感觉到温度不能承受，生命有危险时，为时已晚矣，本能的抵抗力也已经丧失了。 　　无独有偶，行贿者拉拢官员时，也往往是从小恩小惠开始的。据说大贪巨蠹们的“处女贪”，专家统计大多在数百元到两三千元之间，这个数字远远达不到刑法定罪的标准，送者很容易冠以各种诸如‘过节费’、‘酬劳费’、‘生活补助’的名头，受者欣然接受，以为情理之中，不用担心法纪追究累及乌纱。沉浸在这种温柔舒适的感觉中，贪官们就像那只在凉水里悠哉悠哉的青蛙一样，生理上的条件反射丧失殆尽，心理上的警惕性逐渐丢失。于是乎，贪欲似洪水，一旦开闸泄洪便四处泛滥；恶念如锅中沸油，沸腾不息，根本无法平静。随着恶欲之火越燃越旺，法纪防火墙发挥其最终威力，贪官们只有落得个粉身碎骨的下场。 　　“河北第一秘”李真第一次接受礼金时，还“惴惴不安”，在向领导请示后，坚决地将其全额退还；然而，其抗腐蚀的防线没有持久加固，下一次收到羊毛衫的纪念品时，开始松动，并“忐忑不安”地予以接受；于是乎，愈演愈烈，接着“悄悄的”收下一条中华烟……不知不觉中，防线崩溃，变成“心安理得”的接受礼金，贵重礼物；甚至主动出击，索，拿，卡。就这样，李真慢慢成了一个不折不扣的背叛者。 　　在震惊全国的远华走私案中，厦门海关原副关长接培勇最初对赖昌星一直保持着戒心，曾经写下“一旦陷入其手，势必不可自拔，甚至卖身为奴”的自警之语。然而当走私头目赖昌星煞费苦心，以重金弄来一套175册的绝版名贵书籍，送来由9位名画家合作的一幅牡丹图，请全国知名的书画名家到“红楼”与他切磋时，这位官场雅士还是做了“温水中的青蛙”，为赖昌星走私活动大开绿灯，加以庇护。他自己也被那锅煮沸的热水烫得体无完肤，终于锒铛入狱，在高墙电网里度过20年。 　　孟子曰：“路虽迩，不行不至；事虽小，不为不成。”诸葛亮在《出师表》中也提到“勿以恶小而为之，勿以善小而不为”。防腐拒变，保持本色，从源头开始，从小事做起，从点点滴滴开始，只要将恶欲扼杀于萌芽状态，将陋习抹杀于摇篮之中，不给其留有滋生的土壤，自然就会远离蜕变，不会变质。需要个人坚强的意志，保持清醒的头脑，不断的学习贯彻党章，为民、务实、清廉。还需要有效的监督机制，树立正确的道德观，利益观，权李观。“沧海横流，方显英雄本色”，所谓英雄，既能经得住血雨腥风，艰难险阻的考验，也能经得住灯红酒绿，花花世界的考验，始终以一颗平常的心来面对诱惑和利益，却以积极的心来工作和生活，“千磨万击还坚韧，任尔东西南北风！”　 　　对于个人发展过程如此，对于国家发展也是如此。走进人类历史的长河，任何一段文明的兴亡更迭，任何一个民族的兴衰起落，任何一个堪称伟人或英雄的胜败沉浮，无不与其后期的腐败变质有着难以割舍的不解之缘。“以史为镜，可以知兴衰；以人为镜，可以知得失”。从古代恺撒大帝开创的罗马帝国到中国盛极一时的唐宗宋祖、成吉思汉，他们所开创的一代帝国的宏图伟业，无不败倒在他们继承者的荒淫无度，腐败成风的灾难性环境中。秦王嬴政一统六国，企图“打下一个大大的江山”，并劳民伤财，北筑长城使之“固若金汤”，然而，帝王基业在其继承者秦二世胡亥的声色犬马，醉生梦死中很快昙花一现，轰然坍塌。 　　纵观我国封建文明历史中十几个王朝的兴衰沉浮，其最后没落直至灭亡的原因都与腐败脱不了干系。腐败之害由此可见。无论是秦汉隋唐，还是宋元明清，开国初期，都是有一代明主励精图治，，勤恳为政。他们如同“扔进沸水里的青蛙”，深知江山来之不易、百姓生活疾苦，他们日夜勤勉，修复战乱给国民带来的创伤，巩固立足不稳的统治，还要时刻警惕外敌侵扰，随时准备对外扩张，建立帝王基业。因此，每个朝代的初期，都是一派繁荣，蒸蒸日上景象，出现诸如“开唐盛世”、“贞观之治”、“康乾盛世”……随着帝王基业的建立，国家太平，百姓安居乐业，统治者往往歌舞升平、刀枪入库、马放南山，逐渐安于享乐，疏忽朝政。如同“扔进温水里的青蛙”一样，悠闲自得的游来游去，好不惬意！这种放松警惕，麻痹的心理，使国家仅仅维持统治，谈不上图治，更不要说有为。然则“学如逆水行舟，不进则退”，统治亦如此，骄生的思想一旦滋生，腐败成风，统治者沉浸于花天酒地，，骄奢淫逸　，成日声色犬马，醉生梦死，，如同在“不断加热的温水”里一样，国家处于岌岌可危的地步，统治随时面临分崩离析的可能。终当民怨载道，祸乱不断，四面楚歌时，统治者再奋起作为，为时已晚矣，“沸水里的青蛙已丧失了反抗的本能”。明崇祯帝可谓废寝忘食，勤恳为政，企图挽救大明的江山；清光绪帝满腔热忱，执着变法，希冀力挽狂澜，拯救大清的统治。终因国家衰落，腐败成风，百姓水深火热，历史的车轮积重难返，，只能被”活活煮死”。 　　由此可见，无论个人还是国家，保持本色，防腐拒变，应防微杜渐，未雨绸缪，勿做温水里的青蛙，。“加强教育，发展民主，健全法制，强化监督，创新体制，把反腐败寓于各项重要政策措施之中，从源头上预防和解决腐败问题。”　 　　古人说，“良医者，常治无病之病，故无病；圣人者，常治无患之患，故无患”。《鹖冠子》中有一个故事：“魏文王问名医扁鹊，你家兄弟三人，哪一位医术最好？扁鹊回答，大哥最好，二哥次之，我最差。文王问，那为什么你最出名？扁鹊说，我大哥治病，是治病于未发之前。由于一般人不知道他事先能铲除病因，所以他的名气无法传出去。我二哥治病，是治病于初起之时。一般人以为他只能治轻微小病，所以他的名气只传于乡里。而我治病，是在病情严重之时，所以大家认为我的医术高明，名气因此响遍全国” 　　“良医治未病”，建立一系列有效的监督体系，，从根本上防止蜕变，任重而道远。对于已经病起的，抓紧治疗，还有挽救的余地。病入膏肓之人，诸如贵州省委书记刘方仁、河北省委书记程维高　、原中国建设银行行长王雪冰、原中国发展银行副行长胡楚寿等等累累罪证之流，饮鸩止渴，终将自食苦果，罪有应得。“嗜欲喜怒之情，贤愚皆同，贤者能节之，不使过度，愚者纵之，多至失所” 　　呜呼，反腐倡廉，应防微杜渐—勿做温水里的青蛙！ 收起阅读 »

累啊!
天天要写超差代用啊,天天有异常报告!

八、事情没做完呢，下什么班！？
老朱的名言，就是这句话，带动着报关行的同事们，开着小奥拓照样激情在报关第一线，发扬着与天斗其乐无穷；与地斗其乐无穷；与海关斗其乐无穷的精神！是******报关行一次次成为海关的报关行大会上被点名表扬最多的明星报关行。
自己从听到这句话以后，就牢牢的记住了：事情没做完呢，下什么班！？ 收起阅读 »

七、先做人，后做事
第一天到菲亚伏上班，王总就找我说话，说了大概15分钟吧，除了说公司的情况，具体的内容都不记得了。只是一直记得这句话：先做人，后做事！

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英语学习的好网站
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中国影视论坛
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DNV就不用说了吧
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TUV也不用说了吧
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生产FEP色母的NB公司,
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中国机械CAD论坛,门槛很高的
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文化安全网,MSDS的好地方
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日本大金公司,生产FEP的NB厂
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本田的汽车教室,汽车基础知识的绝好课堂
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中国汽车技术网
http://www.iec.ch/cgi-bin/procgi.pl/www/iecwww.p?
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电脑技术论坛
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中国IT实验室
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收起阅读 »

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Highly Accelerated Stressing of Products With Very Low Failure RatesHarry McLean, Reliability EngineerHewlett-Packard Co. Vancouver DivisionVancouver, Washington Written 5/90 - 10/91Minor corrections and reformatting 6/01
BiographyHarry McLean has worked for Hewlett-Packard for the last twenty-three years with many different responsibilities. During the last four years he has been responsible for manufacturing product reliability improvements. Most recently (the last year and one-half) he has been responsible for selecting and implementing a better method of verifying that the division's outgoing failure rate has not unexpectedly increased. Previous papers written by Harry dealt with programming a Hewlett-Packard 1000F Mini-computer system to better manage a manufacturing facilities department. Harry received his BS degree from Northeastern University in Boston.
IntroductionThis paper is a focused implementation of ESS or Environmental Stress Screening in a highly focused use -auditing rather than screening. At the end of this article is a glossary of the unique terms that are used herein.The problem of improving the monitoring of our out- going product quality is an issue that we have addressed during the past four years as we have been lowering the overall failure rate. A newly released product has most of its major issues resolved by the time it is introduced and plans are in place to correct any other known deficiencies, however minor they may be. The problem is then to monitor the out-going product quality in terms of reliability. We have had a number of test plans in place but none of them was very successful. Our problem is aggravated because of the long expected personal printer life (in excess of three years) and very low failure rates. More than 20 printers operating for many months were required to provide the necessary confidence levels (>80%) in order for it to be released to customer usage. Since our printers use cut-sheet paper and have replaceable printhead cartridges, they require constant monitoring by someone during testing. The time to perform a life test has caused us to turn to innovative methods for determining the product's life and failure rates with at least the same confidence levels as before. A further complicating factor is that we have never had a PC board failure at room temperature but have had some during BEST qualification. This makes the in-house testing a bit suspect because it does not correlate with what our customers are experiencing. This paper will discuss the solution of monitoring our out-going product quality which meets our needs.Typically, products that have been screened or audited by stresses should not be shipped to a customer until the proof-of-screen confidence levels have been met. This proof-of-screen is done so that the manufacturer can be assured that the customer's unit will meet or exceed its published or design life expectancy even after it has been stressed. In our case, this requirement would mean that many months would pass before products could be shipped and the delay for the proof-of-screen test to conclude was unacceptable. Hence, the requirement was to determine a life test that would not be as time consuming as “conventional”, life tests. The decision was made for the HASA project to begin by stress auditing PCAs. PCAs represent about one-half of our field failure rate. The decision to begin by stressing PCAs was also reached because a typical printer has many parts with different coefficients of expansion. When a unit has failed, the failure must be isolated and root cause reached so that corrective action can be evaluated and implemented. This meant that we either increase our time to introduction of HASA into manufacturing or buy a second chamber-system. Neither solution was acceptable because we had not yet proven that this process would work with our products. Regardless of whether one chooses to stress PCAs or finished products, some form of proof-of-screen is required. There will be further discussion on proof-of-screen later in this study.
Proposed Test & TheoryIn HASA, each PCA is subjected to a stress environment which is tailored for that PCA type because a screen developed on one PCA may not necessarily be an effective screen on a different type of PCA. The stresses applied were; triaxial random vibration, temperature slew rates approaching 30°C/min, temperature dwelling, and power line voltage and frequency variations. Although the level of these stresses is much higher than that experienced in a customer's environment, it has been the experience of many industry leaders that use accelerated stressing that when failures are uncovered and corrected, field failures likewise are reduced/eliminated. The first PCAs which were tested via the HASA process were not designed with built-in testability nor were there any confidence that they were rugged enough to survive the harsh stresses. We were pleasantly surprised when the PCA's worked very well under the stressed conditions without any design changes. In future products HASA testability will be implemented during the design phase. Typically, if a PCA is stressed for some number of cycles in HASA and if it does not fail, it can be shipped to the customer provided that proof-of-screen has been done. Even if a PCA fails it can be repaired, analyzed for root cause and shipped with the same degree of confidence of a non-failing PCA. The proposal was to stress a number of PCAs in HASA until they all failed. This group of PCAs became the control lot. The failure time, in test stress cycles, would be tracked with each PCA. The "time to failure" versus "percentage of population" would then be plotted and a normal distribution hopefully would result. The information from this distribution would provide the minimum number of stress cycles to end of life as well as the standard deviation of the distribution of failure times and the maximum expected life. The expectation is that with a large enough lot, both normal as well as infant mortality distributions could be seen.Since the failures which are not infant mortalities are due to fatigue and fatigue is an accumulation of stresses, the test can be halted and resumed many times with the same stresses because of the proportionality which was derived from Miner's equation.where, D, the cumulative fatigue stress, n, the number of stress cycles, s, the stress, ß is empirically derived and its value is between 8 and 12.An example of how this proportionality would be applied is to crimp a component lead so that the cross-sectional area is reduced by 50%. The stress at this point would be twice the stress at the same point on a good part because n(2s)ß rather than simply ns ß . Simply stated, defective parts are readily uncovered without sacrificing much of the life of a good part because the equivalent stress fatigue accumulation on the weak part would be many times that of the good part. For more information on Miner's equation, see Lambert's papers listed in the attached bibliography.On-going Monitoring of the Production ProcessThe objectives used for the HASA project were defined before the project began.


Detection of major manufacturing or vendor process shifts that would cause the out-going failure rate to increase by twice the baseline rate
Detection of problems in-house that would cause shifts in the out-going failure rate ōf =5% before they become customer dissatisfaction issues
Tested products in HASA would be shipped
On-going reliability feedback for product improvement
Testing must be achieved without becoming an obstacle to the production process.
Addressing each of the above objectives, we first selected the appropriate statistical equation for sample size N,Since the sampling that we need to do is a small proportion of an ever-expanding population, we selected a sampling plan that would meet our primary objective. That objective is to rapidly detect any major process shift. We chose Equation 2 and its only relationship with the original lot is the standard deviation, s , and the shift from the mean that we wish to detect, d . Nowhere does the equation state that we must have a sample size that is some proportion of the overall population. This is ideal for this type of problem because we are dealing with a very large, growing population and we only wish to detect some predetermined shift in its mean. The sample size to be tested (audited by HASA stresses) is NOT a function of the total population but is a function of the failure rate present in the population and the shift which we wish to detect. The following equation was used to calculate the sample size. Please note that this equation is the same as Equation 2 because as t a approaches Z , t ß approaches Z ß . The variance s 2 for this kind of data (binomial) is equivalent to p q and D is equivalent to d . where, Z & Z are the values from a normal distribution with 100 a (100 * ß ) percentage of area above itwith a being the risk of rejecting the hypothesis that the mean had not changed when it really had not changed. ß is the risk of accepting the hypothesis that the mean had not changed when in reality it had changed. p is baseline percentage failure rate which is the same as the out-going failure rate,

q is 1-p,
D is the change in the failure rate which is to be detected with probability ß and,
N is the sample size over a period of time in days.


By using Equation 3, with different values of a , ß , p, q, and D, yields the various sample sizes N (see Table 1). The "Days" column indicates the number of days that it would take to stress the necessary sample quantity N by sampling at 64 units per day. The "#Defects" column are the defects caused by the increase in failure rate, D, that would reach the customer and cause the out-going failure rate to rise from p to P+D. The "# Defects" column was calculated from an arbitrary daily shipment level of 1,000 units/day and an assumption that the daily sample level of PCAs would be 64 units. This is calculated by the following equation.Eq 4. #Defects = Days D Ship LevelIf the sample size is lowered for a given failure rate p and shift D, the confidence is, therefore, lowered. For instance, if we use the first row in the chart as an example and halve the sample size (N = 1,111), maintain Z at 0.842, the resulting Z would be lowered to 0.62. In other words, the risk would increase from 20% to 27%, which is a risk in allowing a bad lot to ship (because the mean had shifted). This, of course, defeats the purpose of HASA as an early detection of major out-going failure rate shifts before products reach our customers. By the way, the last row indicates that if we had a major shift in our product quality (e.g., a failure rate shift from 1% to 3%) it would be detected with a sample size of 112 units in just under 2 days with a 90% probability.There is no "magic solution" as far as which choice in Table 1 is the best. Selection of the risk () and the probability () must include the sample size (N) because as a and ß get smaller, the sample size will increase. The amount of the large shift (p) on the out-going failure rate (D) is also important because anything below this number is being acknowledged as acceptable and will not be a source of customer dissatisfaction. In essence, one must carefully evaluate all of the parameters and their impact on profitability.
Screen DevelopmentAll of the stressing of the PCAs was done with the print mechanism, power supply, and head driver PCA located outside of the chamber. These assemblies, in turn, were connected via a set of seventeen-foot shielded extension cables to the PCAs in the chamber. The PCAs were fixture mounted in the chamber in a fixture which could hold two PCAs simultaneously. The fixtures were bolted to the vibration table top {the chamber floor) and there was space to stress sixteen PCAs at one time. The stress levels were developed by stressing two randomly selected PCAs until either ceased to perform at the Destruct levels (see Table 2). It should be noted that when selecting the hardware that will interconnect the hardware which is external to the chamber to that which will be stressed, select components (cables & connectors) which will meet or exceed the environmental extremes that will be used. The actual level selected for the HASA stressing was then set to a level that was far above the Operation and Design Levels but below the Destruction Levels (see Table 2). During the screen development, the PCA's under test were subjected to the environmental system maximums (Destruct column) and did not fail -a tribute to the design. Table 2 shows the stress levels for which the PCAs were subjected and subsequently the screen levels selected.


Figure 1 is a representation of the actual screen but please note that the AC line frequency and volts were cycled twice, once during each vibration cycle at each temperature extreme. Nominal, 120V, 60- Hertz power was applied during the 25°C soak and during the up-going ramp. At the end of the screen, a soak at 25°C was done at nominal power line with a "tickle" vibration of 3Grms in which the operation of the PCAs was checked.

Notes:



The keypad LED's alternately flashed at 140C and returned to normal at 130C.
The keypad LED's alternately flashed at 79Volts and returned to normal at 87Volts.
All of the qualification testing was done on single and dual axis vibration and as of the writing of this paper, I am not aware of any correlation between these and triaxial random vibration.
The vibration was turned on for two 2-minute dwells at each of the two temperature soaks. Each vibration on cycle was followed by an equal off time of two minutes.
Slew rate is measured with the thermocouple fastened to the PCA via a crimp lug, i.e., this is the product temp slew rate.






The Equipment The decision to use random vibration was made by studying published papers on the subject in which comparative studies of single, dual axis, and triaxial shakers were made. Additionally, users of this technology were interviewed and their conclusions carefully analyzed.Although there are many assemblies within the HP9000 computer and other system modules, here is a simplified block diagram and the equipment used in the HASA system (refer to Figure 2):



Envirotronics Model EV70LN2, LN2 based chamber.

Model ORS 300CE, Triaxial Random Vibration.

JC Systems Model 620 Environmental Controller with FastTRAC ® & HPIB.

Hewlett-Packard 9000 Series 300 Computer with Unix ® Version 7.0.

Elgar Variable Voltage & Frequency Source Model 751SL-12, 9012-1 Oscillator & T option.

Hewlett-Packard 3488A Voltmeter with (2) 44471A Relay Boards.



The LN2 based system was a requirement because of the high temperature slew rates. An equivalent compressor based system, if available, would have huge compressors, consume a great deal of AC power and be susceptible to relatively high compressor maintenance. The LN2 chamber does not have the shortcomings of the compressor- based system. An oxygen depletion alarm, located in the area of the system for detecting LN2 leaks, is also required. The chamber is actually capable of temperature slew rates in excess of 60°C/minute.The in-house designed modules for controlling the printers in serial, parallel, and RS422 modes are not included in the above list and they are not commercially available. The sixteen-channel power mux module which interconnects the Elgar to the printers under test was also designed in-house.All of the software for controlling the system was written in C on the HP9000 Series 320 computer over a period of one year. Each function was developed independently, i.e., there are separate modules for vibration, power, temperature, and printer control. Each can be run separately which helps enhance the step screen development work. All of the program modules access a master table with the values for soak times, ramp times, events, delays, etc. This, of course, simplifies the programming as well as the user interface which is in XWindows. An example of the vibration table parameters are listed in Table 3. All of the times in the table are in seconds.



The Results of the Initial TestingFor a period of one and one-half months, sixteen PCAs were subjected to a number of stress environments. Each of the different stresses were documented and they varied from the final stresses in terms of slower temperature slew rates, longer temperature soaks, higher vibration levels as well as longer vibration dwells. The far right-hand column values in Table 2 were the final selection of stress levels to begin auditing of production PCAs. During the one and one-half months, none of the PCAs failed the stressing, and this became a source of frustration because failures are needed in order to verify the stress screen design. All of the PCAs that were screened were predominantly SMT (Surface Mount Technology) in nature although there were about twelve axial feed-thru type components. The next step then was to attempt to "seed" defects onto some new PCAs to see if the screen would detect the problems.In checking with people that had experience with screen development, we found that they had very limited experience in seeding SMT boards. Unfortunately, vendors don't normally keep a supply of process defective parts that work at room temperature and fail at either high or low temperature or during the ramping which could be used to seed boards. One, therefore, has to be creative in obtaining boards or components that work at room temperature and fail during the HASA stressing. An attempt was made to seed boards by having our PC repair people create problems that would pass the PC testing but later could fail in HASA. The first batch of sixteen boards were stressed for 98 cycles with only two plug-in ROMs becoming unseated during vibration at six and thirty-two stress cycles respectively. The results were not very encouraging and a second attempt was made to seed samples. Once again the same people were asked to create problems such as remove the solder from critical leads on certain components, thump the crystal on one or both sides and reverse the polarity on two electrolytic capacitors which were in the 5V supply. All of these problems had to pass both the PC test process and a mainframe test. The results of the stressing on this second lot of sixteen boards were even more disappointing because no boards failed after thirteen stress cycles. Once again, the ability to successfully seed SMT boards eluded us. A brainstorming meeting was next held with the PC test technicians to see what we could do to verify that the HASA process would work in our production environment. We uncovered an area in our PC manufacturing process that did a 100% visual inspection of the boards while they were still in panel form but with many of the components already loaded. At this station, the operator can either accept or reject the board(s). If rejected, it is reworked or scrapped. Since the SMT process is not perfect and solder defects occur, an attempt was made to isolate a number of PCAs that were visually rejected for "no-solder", "poor solder" and the like. After these PCAs were located they were marked and sent to the test area after all of the components were loaded. Once again the boards passed both the PC test system and the mainframe test.In our production process we have a return path for boards that pass PC Test and fail during top level testing. These boards are returned to the PC Test area for retesting. If they pass they are returned to the Top Level Assembly area once again and labeled as No Trouble Found or simply, NTF. Twenty-two of these NTF boards were diverted and sent to HASA for evaluation. The results were dramatic -SEVEN boards failed within three stress cycles. Here are the details:



No solder on ROM enable lead on SMT part (One cycle).
No solder on one of the address lines (One cycle).
Intermittent solder short on I/O reset line (One cycle).
Intermittent solder short from 5V to ground (Two cycles).
Defective RAM (Two cycles).
Intermittent short from 5V to processor IC (Three cycles).
Undetermined at this point (Three cycles).

In the normal course of events these boards would have been returned to the final product assembly area and placed in a printer. Later, possibly passed the final product testing and subsequently shipped to a customer -a few potentially dissatisfied customers.Following the testing of the NTFs, a batch of 42 boards were returned from our customer field repair center. These boards had all been either shipped mounted inside of a printer or shipped directly to the repair center for usage in the repairing of customer units. At one time or another, during the previous four months, all of these boards were sent to the repair center board test system because they had all failed. All of the boards were found to be either NTF or intermittent by the repair center. Once again, the stress screen proved to be valuable in inducing the latent problem to patent. EIGHT boards failed within three stress cycles. Here are the results:



Defective ASIC (Application Specific IC).
Defective 110 communication buffer chip.
Defective processor.
Copper flakes under solder mask causing short circuits,
Defective character ROM.
Poor solder wetting on two assemblies.
Shorted Zener diode.


While all of the stress auditing of the above lots was going on, a group of fifty PCAs began a "life" test. The first group of sixteen PCAs was placed in the chamber.The objective of stressing these boards was to stress all of them until they all failed. From this data it was hoped that a normal distribution could be obtained with a small distribution "bump" early in life that would indicate infant or premature failures. During the first two stress cycles four PCA's failed. These boards were removed from the test, repaired, the parts analyzed and then returned to the "life" test. At the end of two and one-half months, the stressing of sixteen of these boards was stopped at 1,251 cycles because no predominate failure mode was detected. Throughout the "life" test, failures occurred and most of them were attributed to the same ASIC that was the predominate failing component from the field return PCAs. The failure mode for these parts was a phenomena known as “delamination”. The basic explanation for this failure mode is the separation of the epoxy case from the metal interconnects which in turn causes voids in which humidity can be trapped. Over time, the humidity will cause the part to fail. All of these parts were photographed using acoustic microscopy without opening the parts.A lot of fifty standard production PCAs was stress- screened next. Since the chamber can only accommodate sixteen PCAs, the number of stress cycles for each of the four lots was intentionally different. Two lots were stressed for six cycles, one for eight, the other for thirty-six. The only failure seen could not be sourced when driven to root cause. The remaining 33 PCAs were never stressed to 1251 cycles like the first sixteen PCAs.

Table 4 is a summary of all of the PCA's that were screened during the HASA investigative phase. From the chart it can clearly be seen that this type of process will detect the types of manufacturing process issues that it was designed to detect.







PCA Source

NumberScreened

# StressCycles

NumberFailed

# Cyclesto Fail

Results of Number Failed


Standard Production

16

520

0

7

Used to characterize system


Std Prod/Seeded

34

121

1

6

Bent lead under ROM


Field Returns & FieldNTFs

42

642

9

1 to 3

Delamination, shorts, poor wetting, and old ROM code


Production NTFs

26

96

7

1 to 3

No solder, intermittents


Std Production

17

1251

4

1&2

Included in 7 NTFs


Totals

135

2630

21



Table 4



ConclusionsAs observed by other authors regarding stress screening, the observance and subsequent discarding of failure data during stressing can be costly. Cases have been documented in which failures were explained away as either that "the failure environment was not within the environment that the customer would use the product”, or that, “we haven't seen that failure mode from our field data". Experience dictates that each and every failure needs to be driven to root cause so that corrective action can be decided upon. The corrective action may be to do nothing for whatever reason but the failure needs to be documented as well as the corrective action for future discussion and analysis. The documenting of all failures satisfies two needs, 1) The problems uncovered can be sent back to the R&D team so that the next generation products won't have the same defects and, 2) It provides a historical database from which to draw inferences and conclusions about the product.Here is a list of the conclusions that we have reached regarding the use of HASA:



HASAhas shown to be a very effective tool in detecting or precipitating latent defects to patent in a few stress cycles. All of the recorded failures in HASA have occurred within six stress cycles or within three hours of HASA testing. We will begin using six cycles and try to reduce the number of stress cycles over time from six to possibly four.

HASA should not significantly degrade or deteriorate the useful life of the product. Presently, there are seventeen boards that have accumulated 1,251 stress cycles. If end-of-life is assumed to be 1,251 stresses, then HASA takes 0.5% of the useful life. There is no indication that 1,251 cycles is close to the end-of-life. From this testing, a conclusion that can be reached is that our boards are very robust and under normal conditions should work without any problems for a very long time. 2a- from the above statement regarding life, the PCA's exhibit infant mortality and from this limited sample of NTF's the infant failure rate was 8.3%. It is highly recommend that ALL NTF's be subjected to HASA because of the high failure rate. These infant mortalities would most likely fail within the first few days or weeks of customer usage. 2b- the same seventeen PCAs that were stressed for 1,251 cycles were later subjected to additional environmental testing to insure that HASA had not introduced some latent failure mode(s). The results of this testing clearly indicate that any concerns were not valid since all of the units passed. Here is a list of the testing: 1) A mini-Iife RVT test for 1/10th life at room temperature 2) ESD testing from 2.5KV to 25KV, 3) Design margin which checks 165 possible cases at different relative humidities and temperatures, 4) High and low operating relative humidity, 5) Supersoak, which consists of a 65°C 90% relative humidity soak for 24 hours and, 6) BEST temperature and vibration.

The original goal was to test sixteen PCAs per work shift. This goal will be met because we can perform the testing, including loading and unloading the chamber, in four hours assuming six stress cycles. Over a two-shift workday, two batches of boards (a total of 32 per shift) would be taken from the PC area buffer and returned within the ten-hour shift.

another objective of HASA was that it would not be a bottleneck to manufacturing. Removal of the boards in the required quantities will not be a problem.

HASA needs to have the capability of detecting large manufacturing process shifts in a short time period so that the quantity of defective products reaching our customers is reduced. Statistically, the HASA process will detect a failure rate shift from 1% to 3% in TWO days. A larger shift of course would take even less time. A smaller shift, from 1% to 1.5%, would take 28 days because of the small number of boards that are being tested. Initially, the primary focus of HASA will be to detect large failure rate shifts. This entire statistical system dictates that if no change has been detected in two days that we are 90% confident that the outgoing failure rate has not jumped to 3% or higher. Conversely, we always have the power to detect large shifts but the power to detect 0.5% shifts increases with time until the 28-day mark is reached. At this point we have 90% power in detecting this small shift. See Table 1. With all of the development work behind us we now look forward to bringing on-line a second stress system to be used for product development work. The first new product stressed in the R&D system will be the first product designed at HP with this process in place. The product during the design phase will be stressed to levels far beyond those seen in HASA so that we will know of the product's robustness and will only be concerned about ourmanufacturing process shifts and vendor process shifts. With the R&D system in place along with all of the failure analysis and corrective action processes, the next generation of printers will have lower field failure rates than those currently in production. All of this is done in order to provide a highly reliable product to our customers which in turn will mean a lower field repair expense and higher profits.

The results of the pre-production stressing in HASA indicate that the process will uncover all of those issues that were anticipated. In the future we will be linking the HASA PCA database with the manufacturing and field database. With all of this in place the complete life of a PCA or product can be reviewed from its inception to its eventual scraping.Statistical Limitations The statistical calculations in this paper use the normal approximation to the binomial distribution. This approximation is valid when five or more failures are apparent in the data. Exact binomial probability calculations should be used when working with fewer failures.

Glossary of TermsBEST. The acronym for Board Electronic Strife Test. A combination of test conditions which are used to uncover design or marginal defects in a PCA before it is made in production quantities.

ESS. Environmental Stress Screening. A combination of stresses designed to stimulate a product so that latent defects become patent. Performed on 100% of the products.HASA. The acronym for High Accelerated Stress Audit. It is a combination of stresses designed to stimulate a product so that latent defects become patent. Performed on a sample basis.Latent. A defect which is hidden. In reference to this paper it is a defect which is "waiting to happen". Stresses can cause a latent defect to become a patent defect.LN2. Liquid Nitrogen. Used as a refrigerant.Omniaxial Random Vibration. Vibration which is quasi-random in nature with six degrees of freedom.Patent. A defect which is not hidden.PCA. Printed Circuit Assembly. Includes the basic laminated board and its components.Proof-of-Screen. After the development of the stress screen, a test must be performed to verify that a "significant" portion of the product's useful life is not consumed by the stresses. The significant needs to be determined by the manufacturer.ROM. Read Only Memory. Memory in which data can be read but not written.Slew Rate. As applied in this paper it is the rate of change of the temperature chamber measured with a thermocouple secured to the PCA.Solder mask. A coating applied to the board before soldering which inhibits the solder from adhering to the traces.



BibliographyMany thanks go to Valerie Wildman and Isabel Rosenblitt, our division statisticians for their patience and help. Craig Daniels who was the original project manager at the inception and began the work of sampling and confidence levels for our divisional product failure rate goals and to Dave Shelley, my current manager who has supported my efforts. I also wish to thank the many people who provided their talents in the editing of thispaper.R.G. Lambert "The Shock and Vibration Bulletins 46, 47, and 53". Naval Research Laboratory, Washington, DC. August 1976, September 1977, and May 1983, respectively.R.G. Lambert " ASME Fatigue Life Prediction Under Random Loading". 84-PVP-3, June 1984.Course notes from Dr. Gregg Hobbs. Westminster, Colorado 80030. (303) 465-5988.

Suggested ReferencesStephen A. Smithson "Effectiveness & Economics", 1990 IES Proceedings.Dr Gregg Hobbs "ESS Course Notes".Charles Schinner " BEST- Board Electronic Strife Test", Hewlett-Packard Co. San Diego Division March 89.Bailey & Gilbert "STRIFE Testing", Hewlett-Packard Co Ft. Collins, Colorado November 1982 Quality Magazine.Clifton Seusy "Achieving Phenomenal Reliability Growth", Hewlett-Packard Co Boise, Idaho Disc Memory Division. 收起阅读 »

HALT and Crystal FailuresDavid Rahe
Crystals are an integral component of practically every operational electronic circuit. They are the heartbeat of the product - if the crystal stops, circuit functionality ends.



The technology of crystal packaging has improved over time; however they continue to be sensitive devices with very serious consequences when failures occur. Therefore, it is important to understand how and why they fail, as well as how to prevent common failures. This paper will discuss several experiences of crystal damage as a result of HALT stresses.Introduction
We will begin with a general discussion of crystal operation, manufacture, and packaging, and then follow with an overview of the HALT process.
Synthetic quartz is composed of Silicon and Oxygen (Silicon Dioxide) and is cultured in autoclaves under high pressure and temperature. Quartz exhibits piezoelectric properties which generate an electrical potential when pressure is applied on the surfaces of the crystal. Conversely, when an electrical potential is applied to the surfaces of a crystal, mechanical deformation or vibration is generated, followed by mechanical resonance. These vibrations occur at a frequency determined by the crystal design and oscillator circuit.
The active component of the quartz resonator is the mechanically vibrating plate cut from monocrystalline quartz crystal with a precise orientation to the crystallographic axes. The resonator is plated with silver or gold electrodes and enclosed into a suitable holder. The plating is on both sides of the crystal and is connected to insulated leads on the crystal package.
The physical dimensions of the element and its orientation to the axes will determine the resonance frequency, its initial accuracy, its electrical properties and the temperature coefficient. Common cut designations include AT, BT, CT, DT, SC, X, Y, and Z. These designations are defined in accordance to the angle at which they were cut from the quartz crystal. The cut angle, design of the resonator, and thickness will determine the frequency and temperature characteristics of the crystal.
The AT-Cut crystals are the most widely used cut, providing a frequency range from 800 kHz up to 300MHz and excellent frequency-temperature characteristics. The frequency of AT-crystals is inversely proportional to the thickness of the vibrator which results in an upper frequency limit of 50MHz for fundamental crystals, 150MHz for third overtone, etc.
SC-cut crystals are useful for high-precision ovenized applications. SC-cut crystals are less sensitive to mechanical and thermal stress and provide lower aging and higher Q compared to the AT-cut.


Crystal and Oscillator Environmental Concerns
As mentioned, the cut of the crystal will largely determine the temperature stability. Crystals are prone to drift over wide temperature ranges, and the manufacturer specifies the maximum and minimum temperatures that the crystal device can be exposed to during oscillation. Over this temperature range, all of the specified operating parameters are guaranteed. Crystals are typically low mass devices and frequently absorb the surrounding temperature conditions relatively quickly. Larger mass oven oscillators, especially flask insulated designs, are somewhat immune to thermal shock since the ovens usually have significant thermal mass well insulated from the ambient. Consequently, much of the oscillator circuitry may not see the rapid temperature change or even the temperature extremes if tests are performed too quickly. Thermal shock type tests should include a start-up test to ensure that the oscillator will start at the temperature extremes.
Quartz crystal oscillators change frequency slightly when accelerated. Crystals exhibit acceleration sensitivity and if a designer is careless, so will the circuitry. This sensitivity may be observed in stable oven oscillators by employing the "two-g tip-over" test. When an oscillator is turned upside down, the force on the crystal changes by two g’s (plus-one g to minus-one g). A typical SC-cut 10 MHz crystal will change about 0.02 Hz which gives a sensitivity of about 0.01 Hz per g. Generally, higher frequency crystals will have less g sensitivity but the sensitivity can vary significantly from one to the next crystal and from one crystal holder type to the next. Changing stress on critical components or even slight movement can also shift the frequency, adding to the oscillator's overall sensitivity.

The sensitivity to acceleration means that the random and periodic mechanical vibrations found in many equipment bays (i.e. fans, etc.) and instruments can induce significant phase noise in high-performance crystal oscillators. Crystal holders, circuit boards, and cases can exhibit mechanical resonance giving the oscillator substantially increased sensitivity at particular frequencies of vibration. Careful design and crystal mount selection can move these resonances to high frequencies where mechanical damping is more effective. It is worth noting that the vector nature of the acceleration sensitivity means that the oscillator will be most sensitive to vibration in one particular direction and that there is a plane where the sensitivity approaches zero (any direction orthogonal to the sensitivity vector). In critical systems, the oscillator may be positioned so that the sensitivity vector points in the direction of least vibration or in the direction of best isolation when a vibration isolator is used. The reduction of crystal oscillators' vibration sensitivity is currently receiving the attention of many in the frequency control industry including both crystal and oscillator manufacturers.
HALT Process Overview
The accelerated principles of Highly Accelerated Life Test involve the use of rapid thermal transitioning( 30°C/minute) combined with multi-axis (six degree of freedom) repetitive shock vibration performed over a wide frequency bandwidth. In addition to these stresses, product specific stresses such as voltage margining, frequency margining, and power cycling may also be applied. While the stresses are applied the test units should be fully functionally exercised, in order to detect any intermittent failures.
HALT is a process of step stressing products to identify operating and destruct limitations of the product. The process begins with cold and hot temperature step stresses, followed by rapid thermal cycling between the identified thermal limits, vibration step stress, and lastly, a combined environment of vibration step stress with thermal cycling.
In HALT, the goal is to over-stress the product and to very quickly induce failures. By applying these stresses in a controlled, stepped fashion, the testing results in the exposure of the weakest points of the design. At the completion of HALT, the functional and destruct limits of the product are known, and a “laundry list” of design and process limitations is defined, with corrective actions also identified. In short, the goal of HALT is to quickly break the product and learn from the failure modes that are exhibited. The failures provide the designer the information needed to understand the weaknesses within the product and what risk those weaknesses present to the product reliability.
The objective of the HALT processes is not compliance but results, corrective action, and prevention. In HALT there is every intention of doing physical damage to product in an attempt to maximize and quantify the margins of product strength (both operating and destruct) by stimulating above expected end-use environments.
It is important to remember that the HALT will be made more effective if additional stresses can be incorporated. By combining more and more stresses, you will bring out failure modes that may occur in the field only under a unique stress situation. This can eliminate a failure mode that could cause a lot of headaches if you were forced to look for it using traditional methods after the product was released.
At the completion of the step stress testing, you will have found many valuable failure modes for your product and will have a clear understanding of the margins in your product. Not only will you will know what your limits are, but also WHY. This can give you a unique understanding of the weaknesses in your product. In the end, you will have optimized the design of your product so that it will last as long as possible in the field; the failures the result from the accelerated stresses applied during HALT have demonstrated excellent correlation to failures that occur over time at normal use (more benign) environments.

Test Case Results

The results discussed in this paper are based on test data from several product and crystal types. They represent typical ways that crystals fail during or rather as a result of the HALT environmental stresses.

Test Case 1:


This crystal failed at 20 Grms, when the lead of the crystal can body was severed at the board fillet. It also sustained internal damage to the quartz crystal lead attachment. This failure repeated on 2 of 3 boards tested. The replacement crystal was rotated 90 degrees and epoxied to the board. It survived without failure to 58 Grms, but did fail at 35 Grms and 100°C during the combined environmental testing.

Test Case 2:

This crystal failed at 35 Grms, when a lead was severed from the crystal can body to the board fillet. The replacement crystal was laid flat and epoxied to the board and survived without failure to 58 Grms.



Test Case 3:

This crystal failed at 50 Grms and 100°C during the combined environmental testing when a lead was severed from the crystal can body. The crystal was taped to the board before the vibration was applied in an attempt to replicate a double-sided tape mounting method.

Test Case 4:







This crystal failed at 15 Grms when leads were severed. The replacement crystal was epoxied to the board and survived without failure to 60 Grms. Capacitors that were damaged at this stress level are also shown.
SummaryCrystals can present challenges to design engineers. However, new packaging methods and careful circuit layout can help to minimize many issues. Improved package designs, such as surface mount, incorporate lower mass and higher pin count to support the crystal body. This is normally an excellent solution for mechanical vibration related failures. SMT spreads mass over larger base and uses additional leads and improved lead strength. Regardless of the package style used, the body of the crystal should be mounted flush to the board. This will greatly reduce rocking movement (pendulum effect) of the package and thereby lessen the stress on the leads. Note that there are many other issues not discussed in this paper can lead to frequency drift and crystal failures, including thermal instability from electrolytic capacitor drift, board layout, and package density.

Author BiographyDavid Rahe is employed as the Reliability Department Manager at Professional Testing Inc. Prior to joining Professional Testing, he spent over five years with QualMark Corporation as a Managing Engineer for the Denver Lab, and later as Director of Operations, Western Region, where he managed four domestic and ten international labs. He held positions of Engineering Manager and General Manager at an independent test lab in Minneapolis, MN. With twenty years of experience in the environmental test industry, David has performed hundreds of HALTs on a wide variety of products. David is an advisory member of the quality teams of General Motors, Dell, and Andrew Corp. and serves as Chairman of the IEEE TC7 AST (Accelerated Stress Test) Group Standards Committee. You may reach David at drahe#ptitest.com. 收起阅读 »

作者：Kinuko Mishiro Mitsunori AbeShigeo Ishikawa Yutaka Higashiguchi Ken-ichiro Tsubone 富士通公司通信网络系统部
来自：电子工程专辑

摘要：据统计发现，电子设备出现的故障中有很大一部分是由于焊点接触不良而造成的，尤其是移动式设备，因此焊点可靠性一直是工程技术人员所关注的问题。随着新型器件不断涌现，在应用之前更需要对其焊接可靠性进行详细的评估。本文以移动电话所应用的BGA/CSP器件为例，分析温度循环和跌落冲击对焊点可靠性所造成的各种影响。
近几年来，移动电话体积迅速变小，重量也越来越轻。为进一步降低重量，技术人员又开发出多种高性能多功能组件以减少元器件的数量，并同时不断提高线路板的密度(图1)。


造成重量减轻的一个主要原因是微型器件封装结构的广泛采用，如球栅格阵列(BGA)或芯片级封装(CSP)等。这类器件在应用之前，技术人员已针对其焊点进行了温度循环测试及材料和结构等方面的多项研究，以确保焊点应具有较高的可靠性。 BGA/CSP焊点结构 BGA和CSP能有效地减小线路板面积，但在焊点可靠性方面却存在一些问题，其根源来自于焊点的结构。图2是一个普通四方扁平L引脚封装(QFP)与BGA封装的焊点结构比较情况。

QFP可以吸收大部分因温度变化造成的张力或因其引脚变形产生的应力，而BGA/CSP器件的应力则都集中在焊球上，因此可能会使焊点或线路板开裂而降低可靠性。对BGA/CSP焊点而言，跌落冲击在短时间产生的应力比由于温度变化而产生的长期应力所造成的危害更大。 我们在线路板上安装了好几种BGA/CSP封装器件，同时进行温度循环测试和跌落测试，大部分器件都能通过温度循环测试，但很多却无法通过跌落测试，出现问题的地方有的在器件上有的在线路板上。

图3显示了可能会影响焊点结构和可靠性的几个因素，其中下列因素主要与BGA/CSP焊点有关： 1．封装和线路板焊盘表面类型(镍/锡镀层) 2．焊盘粘着力大小 3．元器件材料 4．焊球及焊点形状 本文主要介绍以焊球形状、封装结构、线路板焊盘和阻焊剂尺寸等为参变量进行可靠性评估所得到的结论。 跌落测试 很难测量到跌落冲击过程中焊点受到的实际冲力有多大，这是可靠性评估的课题，所以将装有器件的线路板顺着器件面向下跌落后，要采用数值分析的方法才能说明BGA/CSP焊球和线路板受到的冲击力。 数值分析表明焊球和线路板的受力情况几乎完全一样，根据分析结果，试验人员在测量应力的同时对装有BGA/CSP器件的线路板跌落测试进行了调整。试验时将普通移动电话从1.5米的高处落下(这也是多数电话能保证正常工作的跌落高度)，然后测量电路板上受到的压力。 在实物跌落测试中，压力大小因型号、螺孔位置和元件布局不同而有很大差别。由于线路板在生产阶段未装入机壳之前同样可能会受到这种跌落冲击，因此也对裸板进行了跌落测试。虽然此时测试样品受到的最大冲击力随跌落高度和样品重量而变化，但它却显示出比装在机壳内时所承受的冲力更大。该测试中的跌落高度设为1米，以模拟从工厂生产线上落下来的情形。 测试时在线路板和器件之间设计了一个雏菊链，当菊链的阻抗出现10%以上波动时，测试样品将被判定为失效。 焊球形状 从结果可看出，作温度循环测试时沙漏形焊球比柱形焊球的可靠性更高，试验人员在跌落测试中用数值分析也证实了这种现象。 两种形状焊球采用同等焊锡量，线路板和器件的焊盘尺寸也相同，只是焊球的高度不同，然后在这样的条件下计算从1米的高度落下时焊球所受到的压力。 试验表明，焊球在此过程中受到挤压的时间只有1微秒，不管是什么样的力，沙漏形焊球受力情况都要小于柱形焊球，因而可以更有效地抵抗跌落的冲击，缓解应力，提高焊点可靠性。但是沙漏形焊球还没有在产品上得到应用，主要是因为在回流焊过程中其它器件焊接时沙漏形焊球不容易成形。 器件封装结构 试验测试了三种封装结构，A型封装将裸芯片粘焊在一个内部多层板上，B型封装将裸芯片粘焊在聚酰亚胺板上并用树脂密封，C型封装则在聚酰亚胺板和芯片间增加了一层人造橡胶。结果发现封装B和C有很大差异，将试验样品从1米高度扔下20次，B型封装的16个样品中有10个失效，而C型封装的13个样品则无一失效。 试验时使用红色墨水来检查裂缝，墨水可以渗透到样品的细微裂纹中并将其染成红色，这样有问题就能很容易看到。失效的B型封装样品其裂缝靠近器件的焊盘，因此两者结果不同似乎是由于封装结构引起的。C型封装在硅芯片和聚酰亚胺板间焊锡相连的地方加了一层杨氏模数为0.9kgf/mm2的人造橡胶，这层人造橡胶能够缓冲器件封装和线路板之间由于跌落冲撞而产生的挤压力。 线路板设计 试验还测试了两种线路板，一种的阻焊剂和焊盘没有重叠，另一种阻焊剂则盖住了焊盘边缘50um的区域。 对装有A型封装的线路板进行检查后发现，大部分失效样品都属于阻焊剂和焊盘有重叠的线路板，所有样品的线路板和焊锡间都出现了裂缝。可能是因为普通阻焊剂盖住线路板焊盘之后的立体形状有很多优点才采用这种方式。如果焊盘表面镀镍/金或所作的处理不是很好时，焊点里的镍锡之间会形成易碎合金层，此时若阻焊剂过多测试结果还要更糟。另外如果线路板电性附着力很小时，普通阻焊剂更是会经常造成引脚从线路板上脱落。 对这些结果进行综合考虑后发现，普通阻焊剂对本次试验所用的线路板效果更好，可以保证为跌落冲击提供很好的保护，此外焊盘表面处理方式和焊盘粘着力也应在实际设计中予以考虑。 底部填充处理 这次的试验也证明了抗跌落冲击可靠性因封装结构而异，当然，目前不可能把所有的BGA/CSP封装结构都改成C型。对于那些抗冲击性较差的封装，应该先设计出最适合的线路板，同时再采取另外的方法提高其可靠性。为确保从制造到使用各阶段都能保持较高的抗跌落冲击可靠性，我们决定对BGA/CSP封装进行底部树脂填充。 所实施的方案首先不能给生产增加很大工作量，因此先挑选开发出一些易于使用的材料作为备选，这些材料都能很容易地渗入器件封装和线路板内，并可在低温下短时间内完全固化。 试验采用固化条件为150℃/10分钟的环氧树脂E、F和硅树脂G。跌落测试结果表明，杨氏模数较高的环氧树脂比模数低的硅树脂能更有效地提高BGA/CSP封装抗跌落可靠性，另外，环氧树脂E和F的可靠性也不同，使用F的测试样品引脚会从线路板上脱落。 由于树脂E和F对线路板的粘着力不同，分别是2.4kg/mm2和1.7kg/mm2，所以我们估计因树脂F对线路板粘着力不够而造成树脂从线路板上脱落，使得导电焊盘与线路板分离，因此用作底部填充的树脂必须要有较高的杨氏模数并对线路板和器件都有较高粘着力。 从试验得出的数据还可看到，底部填充能够减轻受力大小并加快所受力的衰减过程。不过使用底部填充树脂后，它和线路板或器件封装之间的热膨胀系数(CTE)的巨大差异可能会降低其在温度循环测试中的可靠性。 于是我们进行温度循环测试，结果发现使用了底部填充树脂的A类封装仍然十分可靠，只有C型封装的可靠性降低了一点，不过这在应用中也可以忽略。我们在300次温度循环后对失效样品进行检查，发现C型封装的焊点出现有裂纹。 不过，现实中的移动电话使用了各种各样BGA/CSP封装，其粘附表面和热膨胀系数(包括密封树脂)完全不同，所以应该在对BGA/CSP封装和电路板材料的发展趋势作进一步研究的基础上，开发出符合要求的新型底部填充树脂。 本文结论 我们对移动电话中的BGA/CSP封装器件在跌落冲击下的焊点可靠性进行了评估，得出的结论为： 1．跌落对焊点造成的冲击力可以在电路板上测量得到。 2．焊点受到的跌落冲击力因封装结构而异。 3．底部填充可减轻电路板的受力情况。 4．用于底部填充的树脂应采用高杨氏模数和对线路板及器件封装有较强粘着力的树脂，同时还要考虑树脂与线路板和器件封装的膨胀系数。 今后的工作将主要集中在以下几方面：测定张力变化速度及焊点形状对焊点可靠性的影响，以及建立一种能再现跌落冲击力的冲击测试方法等。
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作者：张群 谢晓明 Tom Adams
来自：电子工程专辑

摘要：人们一般都认为，芯片表面与固化底充胶界面分层是基板倒装芯片(FCOB)封装最常见的失效原因，失效主要是因为底充胶分层扩展导致焊接凸点连接断开。但是一些相关数据显示的情况却并不是这样。本文重点讨论FCOB焊点在经过温度循环实验后的性能退化问题，同时研究焊点裂纹的产生和生长以及焊点微观组织粗化的影响等问题。
在实际应用中，一些FCOB中没有出现分层，但焊接凸点却脱开或裂开；而在另一些FCOB中，底充胶分层出现在一个或多个焊接凸点周围，但又没有马上就发生失效，甚至还观察到焊点断裂而没有立刻造成电气功能丧失的情况。


为了深入了解FCOB中焊点性能退化问题，中科院上海冶金研究所和德国法兰克福的戴姆勒·克莱斯勒研究所共同开展了一个研究项目，重点研究倒装芯片焊点在经过温度循环试验后的性能下降问题。温度循环可加大基板和硅片之间热膨胀系数(CTE)严重失配造成的影响。温度循环产生的应变在裸片边角处最为严重。该项研究还希望能解决一些其它问题，如焊点裂缝是怎样萌生的？这些裂缝如何蔓延？焊点微观结构粗化的作用是什么等等。 试验采用Flip Chip Technology有限公司制造的芯片，芯片尺寸为6.3×5.6mm，周边有96个SnPb共晶焊接凸点，凸点间距为203μm，交错的焊盘连在一起形成一个菊花链结构。芯片焊接采用峰值温度为230℃的红外(IR)回流焊工艺，基板为FR4印制电路板，上面有带Ni/Au镀层的Cu焊盘。液体底充胶在基板加热到60～70℃下沿芯片一边进行填充，然后在150℃下经过20秒固化。另有部分试验芯片没有进行底部填充，用以确定焊点在没有应力保护情况下的平均失效时间。 试验芯片在-55℃和125℃温度间进行温度循环，高低温的驻留时间为30分钟，转换时间在10秒之内。大约每200次循环后就对试验芯片的电气导通性和焊点电阻进行一次测试，并应用Sonoscan D-6000 C-SAM声学显微镜对试验芯片进行声学成像，另外选择部分芯片进行金相剖面分析并用金相显微镜观察焊点。

没有进行底充胶填充的芯片平均经过约100次热循环之后出现电性能失效，而做过底充胶填充的芯片一般在2,000多次温度循环后才会失效，可见底充胶材料可使温度循环应力得到缓解，使倒装芯片封装件的寿命提高20倍以上。 对进行过底充胶填充的倒装芯片做声学成像是为了对裸片表面和焊接凸点之间的焊点进行非破坏性定性评估。焊点中的裂纹与其它不连续型缺陷一样，可以将所有的超声波反射回换能器中，所以有裂缝的焊点发出的回声其超声强度要高于完整焊点的回波，在声像图中表现为具有较高的图像衬度。由于裂缝横穿焊点生长，焊点在声像图中也会越来越亮。运用声学显微成像能够非破坏性地确定哪些焊点开始萌生裂纹，并以此作为选择样品进行破坏性分析的依据。 在试验中选出符合下面三个条件之一的芯片进行金相剖面分析： (1) 芯片具有电性功能，且C-SAM成像时没有出现裂纹或底充胶分层。 (2) 芯片具有电性功能，但在声像图中显示有底充胶分层。 (3) 芯片有开路或瞬态开路，并在声像图中出现底充胶分层。 结果发现，只有那些在声像图中衬度有增加的焊点在金相剖面分析中发现了裂纹，声像图衬度没有变化的焊点未发现裂纹。 图1所示为热循环之前试验芯片一角的声像图，所有焊接凸点的键合点都很暗，表示衬度低，键合良好。图2是试验芯片在772次热循环之后的声像图，有几个焊接凸点变亮了许多，这些凸点所显示的明亮程度与每个凸点产生的裂纹面积相对应。

重要的是，这些裂纹是在没有分层的情况下形成的，分层可以通过声学显微镜观察到，因为它和裂纹一样呈现不连续性特征，能反射几乎所有的超声波。为了对裂纹形成的情况有更多了解，我们再对一些用声学方法观察到裂纹的试验芯片进行金相剖面分析，然后用金相显微镜拍照检查。 图3是一个裂纹刚刚开始形成的焊点剖面图，可以看到焊料的微观组织发生粗化，这种粗化在照片上部焊点和裸片表面交界处附近更加明显。以前的有限元模拟研究表明，微观组织粗化区域与焊料中产生的应变相对应，粗化和应变在凸点最接近芯片表面的区域最为常见。 由于微观组织的粗化会随着热循环次数的增加而加深，结果将不仅仅使裂纹变得更大，裂纹还会更快地蔓延穿过焊接凸点。图4是一个穿过了整个焊接凸点的裂纹。

综观整个研究，裂纹产生于底充胶与芯片表面分层之前。焊点主要的失效原因是微组织粗化造成开裂，而不是因分层引起的断裂，但似乎有理由认为，完整焊点早期分层的确会引起焊点断裂。分层可能由CTE失配应力引起(此应力在裸片的边角处较大)，或因裸片表面与底充胶之间粘接失效而引起。 从一些焊点已经完全开裂但却没有电性能失效可以看到，分层对电气连通性的影响各不相同。在温度循环期间不间断地进行电阻测量，可以确定出焊点的电性状态。看起来固化后的底充胶其收缩力足以在开裂之后保持一段时间的电气连通，经过多次温度循环之后，或许由于分层的扩大，这个收缩力会消失，造成焊点最终失效。 本文结论 在这组FCOB中，芯片表面与底充胶之间的粘接力相当高，焊点失效的主要模式是由共晶焊料微观组织粗化引起的开裂，而不是由于底充胶与芯片表面脱离而引起的分层。温度循环期间，焊料组织粗化引起的失效大大早于分层引起的失效，焊料与底充胶之间的相互作用是相当复杂的。试验中还对已经发生完全断裂但没有立刻丧失电气功能的那些焊点进行了观察，了解焊点失效的相关原因将有助于提高FCOB的整体可靠性。 收起阅读 »

这是你在电子组装产品失效分析之前、之中和之后所需要知道的知识参加过关于失效情况讨论的人都知道，一个客观的、 独立的失效分析的价值是多么重要。 失效可能由一系列的原因造成：设计的缺陷、不好的材料质量、制造问题、运输或储藏条件不当、在操作时的过荷等。大多数公司 缺乏深入调查的设备，而这往往是解决某些问题所需要的。没有对失效进行正确分析，采取纠正措施的努力可能是无用的，或者产生事与愿违的结果。　　失效分析实验室通常比一个高级的测试中心具备更多的专门仪器和专门知识，以便发现失效的问题根源及其产生的事件链。在调查的时候，分析专家将会决定进行哪种测试，以及按什么顺序把调查引向迅速的、经济的结论。分析专家也将会根据失效在产品周期中发生的部位以及不同阶段的优先权，推荐适当的纠正措施。如果用户需要具备这些能力,就值得去聘请一位专业的失效分析人员来工作。　　值得注意的是，有时甚至一项很有限的失效分析也是非常值得的，比如当迫切需要消除某个潜在的因素时。举例来说，及时知道某个失效不是由静电破坏引起，就可以避免在纠错行动上浪费大量的金钱。 在失效发生之前应该知道的事　　想得到一个成功的分析结果，在失效分析专家到达现场之前就应该作好准备工作。为了避免犯最常见的错误，所有可能涉及失效情况处理的人，都要具备下列各项预防知识。　　保护实物证据。 如果不知道某样东西为什么会坏掉,就放在那里别动它。在制造业环境中，把一个断的焊点重新焊上或更换一个失效的元件也许是正常的，但它对失效分析家而言是灾难。因为它可能意味着破坏了一个重要问题的证据, 当然，并不是希望人们碰到每个偶发事件就停止制造，并把失效分析专家叫来；但是如果确实存在一种失效的趋势,那么，最坏的做法就是不断地修复出故障的部件，并继续向后道工序发货。　　不要试图把破碎的表面拼接起来。 如果某些东西碎成两半，人们会自然而然地试着去把两者拼在一起。在微观的水平上,两个表面的磨滑和啮合会破坏有价值的证据。如果能向失效分析专家提供一个干净而保护完好的破碎表面,他几乎总能找出损坏的原因，并且帮助决定上星期发出的部件是否需要追回。　　避免过多的加电测试。不要继续不断地试验一个时断时通的零件，这样做会导致线路完全断开。一旦弄毁了失效现场, 分析专家可以得到的唯一结论就是有人曾对该线路加电次数太多太强。　　保护材料免受热、湿气、震动、ESD 和其他的外力。 要使用推荐的保护性包装和容器。　　从失效中收集所有存在的数据。 有些看来与在现场的人无关的东西可能是决定性的。 记住宁可收集了过多的数据而不要收集得过少。并且要确保用记录、照相或至少文档方式，记录曾用过的测试组合。　　别忽视人们的直觉。记下那些不寻常的声音、气味和看到的现象。如有可能,要直接与那些首先看到失效的人员进行交流，他们常常会提供有价值的、与未实际在场的人不同的说法。实物分析 　　如果证据保护得比较好,借助于在传统的测试中心中所没有的特殊的仪器的帮助,失效分析人员就能对从失效现场得到的数据中梳理出很多信息。举例来说，在 Raytheon可靠性分析实验室的电子显微镜放大倍数可达到 200,000倍。 除了知道该如何正确的解释测试结果外，分析专家将会了解哪些测试是真正必需的，哪些是不必要的，从而对影响失效的所有的因素获得一个更全面清楚的认识。　　失效分析调查由对可疑元件的外部检验开始。 根据器件的类型和特殊要求,分析人员可以使用多种技术:包括热阻测试、放射型显微镜、密封性测试、超声扫描或红外成像。然后，分析人员对内部进行调查，失效分析专家有一个特技：即在不破坏决定性证据的条件下把东西拆开的能力。　　解剖精细的元件与其说是科学，不如说是一种手艺。举例来说，取断面不单单是把一个物体切片成两半。这个元件要先被浇铸在环氧基树脂中保护起来,然后经过研磨和抛光形成一个光滑的断面，以便在显微镜下检查。如果分析家正在调查金属之间的分离, 那么一个电子显微镜加上一个X光发射分光计，就能完全地显示出原子的种类，从而识别出分离发生在哪里。这个数据对那些逐层进行金属化的工艺人员是很重要的。 区分主要的和次要的失效因素 　　大多数的失效包括一系列串行发生的事件。 失效分析专家根据实物特征来确定正确的次序时，常常需要创建一棵失效树(图 1)，以帮助指导调查。(一个复杂的失效必须用这个方法来解决。) 图上各分枝列出了所有的可能产生失效的原因，而且指出哪里需要附加的数据来支援或驳倒某个潜在性因素。分析人员将根据不同的可能性，沿图上的各个分枝向下分析调查。最后，分析专家不但可以发现问题根源 ,而且能把整个失效的顺序与原始的症状对照起来。图1. 样品故障分析树形图。在追踪事件的发生顺序时，失效分析人员可能会发现早先的调查中忽视了的细微线索。最近有一位客户来找RAL，想弄清为什么他们的电力控制器器件失效率会这么高。此前， 客户已经把器件送回给制造商检验, 制造商已经确定失效是由于电的过荷引起，这属于系统的缺陷和客户的职责。客户测量了电压并且发现的确存在着电压尖峰, 实际上在马达驱动控制器中这是很普通的事。他们修改了设计以减少电压尖峰，而且失效率确实在一段时间内减少了。　　然而，不久失效率再一次迅速增加，此时客户与RAL联系。 RAL使用失效树进行分析以保证每个可能的失效模态都被考虑到,不只是电的过荷。事实证明，这个部件是在装配期间已受到了机械损伤,使他们装配之后的处理和使用中容易受到影响而失效。上次设计修改后所带来的微小进步，是因为该部件所受到的电压已有改善，不再像过去那样厉害的缘故。　　这个有问题的器件的制造过程中，需要把一个功率芯片装到一个散热片上。在装配的过程中，芯片上受到应力并产生微小的裂纹。随着上电和温度循环次数的增加，初始裂纹在芯片的易碎材料中传播。 在某些情况下，裂纹穿透到芯片的工作区域, 明显地减小晶体管的面积。裂纹的位置决定了这个部件在加上电压后是否会失效。制造商以前错误解释了事件的顺序。 当功率器件失效的时候,裂纹已被根本烧毁了,留下一个坑以及熔化了的碎片。在受过强大的热应力的部件中出现裂纹本来是平常事，RAL断定裂纹先发生,才引起部件的烧毁，而不是像制造商所解释的热应力引起了裂纹。这些裂纹在芯片的封装内部不容易看发现。RAL用超声扫描显微镜,在还没有烧毁的部件中测出裂纹,从而证明了它的理论。最后RAL和制造商共同工作，修改了贴装部件的方式,减少了引起失效的弯曲应力。 调查人为问题的根源 　　在实际中，问题不是自己产生的，而是最终通过人的行动发生的。 检查人的因素超过狭义的技术分析的范围，它可能成为最有价值的步骤。是否在交流或监督方面有基本的障碍? 组织和人员是否因他们的工作好而受到了适当的激励? 操作员所受的训练是否适当? 有时候实物因素会转变为机构组织的问题。　　失效分析专家的一部份作用是找到相关人员工作的最好方式，使得类似的问题不再发生。举例来说,假如问题是一个焊接点上的过热。最容易的办法就是告诉某某技术员，他对焊点加热太多，下次要小心。然而，一个更有价值的纠正行动可能是修订培训计划，让所有相关人员都注意到过热所引起的损害。确定并实现纠正的行动 　　在明确地找到问题根源之后，分析专家将会提出纠正的措施。它可能包括改进制造工艺、采用有较高质量控制水平的供应商的部件、改进设计、修改指标和其他的建议。分析家也将会根据产品所处阶段，提出处理当前问题的方法。举例来说，如果在产品装配之前发现一个电容器失效,那是容易解决的，不安装这个元件就行了；如果在制造已经开始之后发现同样的失效，分析家和客户就必须衡量其它方案。 客户很可能想要拆去坏的元件而换成好的,而这种返工带来的费用和风险可能是不允许的。可能的替代的方案之一是借助环境试验来筛选那些加工完的部件，从中剔除掉坏的产品。 　　最困难的失效情况之一是有缺陷的产品已经发货出厂了，你是否要把它们召回?或者你将要派人去现场更换每个坏部件?对于处在这种困境中的公司,可靠性测试将能决定这些有缺陷的元件失效的机率、其可能的结果、以及行动的正确方向。可靠性分析常常来自失效分析，它可以用来决定有缺陷的材料的可靠性。 这是你在教科书中找不到的信息，因为没有人会有意设计和测试由坏的部件构成的系统。如果他们被迫做这样的测试的话,也决不会把结果公之于众!　　失效分析专家的作法将是利用一个失效样品进行实验,例如，加速的环境应力试验, 以便决定在一个给定的时间周期内失效的概率。其结果将会是经理能用以作出商业决策的数字。例如，如果产品的预定保修期是18个月，那么，其风险程度可能不值得在这之前做特别的产品改进。　　确认纠正的行动　失效分析的最后步骤是要确认纠正措施是否有效。需要确认的项目将明显依赖于改正了什么和如何改正的。如果它是一个生产量的问题,需要确认的当然是:开动生产过程来看是否生产量有提高；如果一个联接件在现场中经过若干年之后失效,分析人员可能设计一个加速的老化试验来模拟长期的暴露环境。设计各种测试条件来模拟不同的环境是一项完整的科学和手艺。　　在这个阶段，分析专家的特长将会帮助客户避免常发生的错误。举例来说, 当评估一个热循环的失效时,多数人会认为热冲击一定比慢的热循环更严峻。因此,他们将会做一个热冲击的试验,而不去做慢的热周期试验。(完成冲击试验将花费较少的时间, 这也可能影响人们对试验的决策。) 然而，在某些失效情况中，慢的热循环可能实际上比热冲击更严峻。有时，有些试验看起来像是不必要的，或违反常人的直觉，因而会被忽视，但它们却是必要的。最成功的失效分析是防范于未然　　当灾祸迫近的时候,大多数公司都愿聘请一位失效分析专家，因为他们需要一个在最后一刻力挽狂澜的专家。另一个可能的关系是在设计阶段，当要比较不同的方法所产生的结果时,需要向失效分析家咨询。　　经过早期的介入，失效分析可以用面向可靠性和潜在失效性的眼光来审定提交的设计，从而在潜在的缺陷上升为问题之前就识别它们。分析专家将会提醒设计组注意料想不到的化学的、电的和机械的应力，以及当前的设计怎么会引起已知的各种失效模态。借助于预先识别陷阱，分析家的建议可以免去将来有可能发生的大规模的失效调查。对失效分析而言，防范于未然是不引人注目的成功,但却是更有效和更可预测的，甚至有利于当事人的血压和健康。 收起阅读 »

看到自己的空间很久没来，发现自己真的不适合开博客，真得很抱歉

旧东西没什么用了,6SQ的朋友谁要可以站内发短信给我.
免费送,你所要付的只是快递费.

有个家伙居然被REJECT了五次.
虽然最后他还是答非所问,每个问题他都在回答论坛的好,而没看问的是什么,I真的是服了HIM.
最后一个问题是问做什么方面工作的,他填的是"虽然没做出什么贡献,但总不能拒绝我加入论坛呀",偶虽然最近心情糟透了,看到这句话不禁一笑,批准了,这也许正是论坛的魅力所在吧. 收起阅读 »

节约开支，到超市去买了一个电烫斗和一个烫衣板回来自己烫衣服。
以前总是把衣服拿到外面洗，顺便就烫好了，每个月洗衣服得100多，买个电烫斗85，烫衣板32，一个月就省回来了，以前那种浪费真该改改了。

天气: 冷心情: 郁闷昨晚做了一个很混乱的梦
没有固定的时间也没有固定的地点
一个场景一个场景的变换
朋友同事亲友同学还有陌生人
走马灯似的轮番上场
或说着话,或做着事......

最近的心情和头脑一如这个乱糟糟的梦
如一团乱麻越理越乱
习惯了逃避习惯了等待明天
时间是可以解决一些问题
可终究逃不出自己那颗敏感的心
很多问题被自己习惯性的合理内化
可积压的多了终会爆发
我该怎么做呢?
到底要怎么做呢...... 收起阅读 »