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1、工艺可靠性设计方法与实践 华为公司工艺可靠性研究业务介绍,工艺基础研究部工艺可靠性研究组 20061124,Page 2,目录,工艺可靠性业务的需求分析 工艺可靠性业务行业分析 工艺可靠性业务组织流程 工艺可靠性业务技术内容 工艺可靠性技术在产品中的应用案例,Page 3,产品中工艺可靠性需求,High Performance Systems 1025年的使用寿命对工艺可靠性设计的要求； 高频、高速信号； 热可靠性问题 高复杂度单板； 封装技术的极限化发展带来的失效。 Mid Range Performance Electronics 5年以上使用寿命； 混合组装； 无铅可靠性问题。 Hand
2、-held/Wireless Electronics 4年以上使用寿命；振动、冲击等特殊应用环境； 高密； 无铅可靠性问题； 低成本问题。,Page 4,工艺可靠性行业分析业界趋势分析： ECTC、SMTA 近年来在工艺可靠性领域的研究,1、不同表面处理条件下的脆性断裂问题； 2、快速可靠性评估方法研究； 3、无铅、密间距焊点可靠性研究； 4、腐蚀与迁移失效机理研究； 5、无损分析和故障诊断技术。,业界采用仿真、可靠性试验以及失效机理的研究方法对典型的板级互连可靠性问题进行研究，包括：,Page 5,Reliability Engineering,FEM,Page 6,业界常见可靠性业务流程,
3、Design Verification,Failure analysis Root cause analysis,results,Predictions / failures,Manufacture & Market product,Field failures,Component count reliability analysis,Long term life test & group testing,Design “rules”,Product Qualification,Product design,results,Parametric distribution yield analy
4、sis,Demonstration of target reliability,SHIP,BETA,ALPHA,FEM,Page 7,工艺可靠性业务内容,工艺对象,环境,可靠性研究方法,结论,焊点 PCB/PTH 辅料 器件 ,基于POF 仿真分析工具 可靠性试验标准 失效分析方法,工作热循环 工作机械应力 功率循环 组装热过程 组装机械应力 存储 运输 气候 环境气氛,设计方法 可靠性规格 DFR设计流程 技术积累,Page 8,工艺可靠性研究内容,挑战: 高密高速、小型化、低成本的市场需求 新技术、新工艺、新材料的不断应用 研发周期不断缩短 新型法律法规出台/环保政策的推行 工艺可靠性研究
5、就是从工艺的角度，控制工艺风险，保证产品的质量波动在允许的范围之内,工艺可靠性研究的主要课题： PCBA的环境适应性 电气互连可靠性。 PCB可靠性； 连接器互连的可靠性。,Page 9,工艺可靠性分析测试和评估能力,无损分析技术 微观组织结构分析 表面形貌分析技术 材料力学性能测试 有限元模拟和仿真技术,Page 10,工艺可靠性设计与产品开发 有限元仿真分析技术,采用Ansys仿真技术对板级热、机械应力进行分析，评估各种工艺对象包括焊点、封装、PCB的热机械可靠性问题，并进行优化设计。,Page 11,工艺可靠性技术与产品开发 工艺失效分析,失效现象,失效模式,失效机理,根本原因,改进预防
6、,芯片级 器件级 单板级 系统级 ,开路 断路 时断时续 ,物理 化学 电学 热学 力学 材料学 ,可靠性设计 物料 制造过程 应用环境 人为损坏 ,DFM DFR 来料监控 ,Page 12,工艺可靠性设计与产品开发 新材料/新工艺/新封装工艺可靠性认证与评估,Influence of Ni-Sn-Cu ternary intermetallic compound on solder joint reliability,Page 14,PRESENTATION OUTLINE,Overview Experiments results Discussion Conclusion,Page 15
7、,Overview,As we all know, Cu-Sn or Ni-Sn binary compound forms at the interface of pad and solder material after soldering.,Scallop Cu6Sn5 1,thin Ni3Sn4 2,Cu6Sn5,Page 16,Overview,But sometimes, things dont happened exactly like this.,Ni-Sn-Cu,Ni-Sn,SAC+NiAu BGA after soldering 3,Page 17,Overview,Som
8、ebody found solder joint brittle fracture between two layer IMC and then attributed to ternary compound.,Ni,Cu,Ni-Sn,Ni-Sn-Cu,Solder joint open case in Qualcomm 4,Page 18,Experiments,Assembly: PCB（HASL / OSP / IAg / NiAu / ENIG） solder（SnPb eutectic / SAC ） BGA（NiAu） Etch: 5%HNO3 + alcohol to remove
9、 solder without cross-section SEM & EDS Solder joint fracture case analysis,Page 19,Results,NiSn binary IMC formed in NiAu/SnPb/NiAu Solder joint,granular sand-like,6000x,Solder joint after solder removed,Ni-Sn only,NiSn binary IMC,Page 20,Disconnected rock formed upon sand in HASL/SnPb/NiAu,Rock li
10、ke column lies upon sand like granules,Just change PCB finishing from NiAu to HASL, things become different at BGA side?,Results,2000x,Page 21,5000x,Sand-like mainly still Ni-Sn（contains a little copper）; rock-like column mainly Contains Ni-Sn-Cu,Results,EDS indicates Ni-Sn-Cu ternary compound,They
11、do exist!,Page 22,If copper exist in ether side of solder joint or inside of solder joint, ternary compoud will form upon nickel layer!,Results,They even exist in almost all kinds of solder joint!,Page 23,Results,It seems like this:,SnPb,NiAu,HASL/OSP,SAC,NiAu,Any, even NiAu,reflow,Ni-Sn(Cu),Ni-Sn-C
12、u,Page 24,Discussion,Why copper can migrate so long distance? Copper is so active with much solubility in tin. Copper can form Cu-Sn IMC more easily and quickly than Ni-Sn.,At the touch second, great many copper diffuse into melt solder even exceed stable solubility,Due to unstable, some copper atom
13、 come back to decrease energy,Copper migration,Touch melt solder,reflow,Cooling begin,IMC nucleate at interface and ternary IMC forms,Page 25,1000x,3000x,Hollow hexagon,Hollow hexagon Cu6Sn5,3000x,2000x,solid trigon,solid hexagon,Discussion,Variable morphology of ternary compound, sometimes like Cu6
14、Sn5,Looks similar!,Page 26,So the column can be identified as (CuNi)Sn5,(a),(b),Diffraction pattern of (a) Cu6Sn5 binary compound (b) column-like ternary compound found in solder joint 5,Discussion,The crystal structure of rock-like column is close to Cu6Sn5,Page 27,Field failure of BGA solder joint
15、 crack , found trigon and hexagon rock at fracture surface without any etching,Discussion,Some solder joint failure cases show abnormal brittle fracture,1000x,Can ternary compound be so terrible?,Page 28,Top side BGA solder joint crack after wave solder, found more strong trigon and hexagon rock at
16、fracture surface.,Some solder joint failure cases show abnormal brittle fracture,Discussion,1000x,Is ternary compound a trouble maker?,Page 29,Discussion,It seems that crack develop between two IMC layers, Ni-Sn(Cu) and Ni-Sn-Cu！,Yes, there do exist micro cracks in IMC layer!,Ni-Sn(Cu),Ni-Sn-Cu,5000x,Page 30,Discussion,Failure j
