inemi STUDY ON BOARD CREEP CORROSION inemi 关于电路板爬行腐蚀的研究 Project chairs: Xiaodong Jiang (Alcatel-Lucent) Mason Hu (Cisco) Simon Lee (Dow Chemical) Haley Fu, inemi CEEDI Meeting, Beijing April 24, 2012
Outline 纲要 About inemi 关于 inemi inemi Creep Corrosion Project 项目介绍 Phase 1: Industrial survey ( 阶段 1: 失效调研 ) Phase 2: Primary factors influencing creep corrosion ( 阶段 2: 影响爬行腐蚀的主要因素 ) Phase 3: Mixed flowing-gas test ( 阶段 3: 试验 ) Test matrix ( 试验矩阵 ) Experimental setup and corrosion uniformity ( 条件 ) Results, discussion and summary ( 结果, 讨论, 总结 )
Introduction of inemi Mission: Forecast and Accelerate improvements in the Electronics Manufacturing Industry for a Sustainable Future. 5 Key Deliverables: Technology Roadmaps Collaborative Deployment Projects Research Priorities Documents Proactive Forums Position Papers 4 Major Focuses: Environment Miniaturization Medical Electronics Alternative Energy International Electronics Manufacturing Initiative (inemi) is an industry-led consortium of around 100 global manufacturers, suppliers, industry associations and consortia, government agencies and universities. Working on advancing manufacturing technology since 1994. Visit us at www.inemi.org.
Phase 1 & 2 Project Members 第 1 2 阶段项目成员
Phase 1: Survey of Creep Corrosion Failures 第一阶段 : 关于爬行腐蚀的调研 45 respondents: 67% of them have experienced creep corrosion failures. (45 个调研样本 :67% 反馈他们曾经历爬行腐蚀的失效 ) Industrial and automotive I ndust r i al and Aut omot i ve - Passenger Compar t ment Telecom + high end servers Tel ecom and Hi gh End Ser ver s Computers and peripherals Comput er s and Per i pher al s Consumer products Consumer 0 2 4 6 8 10 12
Phase 1: Survey - Time to failure due to creep corrosion 阶段 1: 调研 产生爬行腐蚀失效的时间 < 1 year 1-3 year 3-5 year > 5 year 14 12 10 8 6 4 2 0 <1 year 20 18 16 14 12 10 8 6 4 2 0 1-3 year s 3-5 year s Act i ve Compone >5 year s Passi ve Compon I nt er connect ( I ndust r i al Tel ecom I ndust r i al Comput er Tel ecom Consumer Comput er Consumer
Phase 1: Survey Component Types 阶段 1: 调研 元件类型 Active Passive Interconnect 20 18 16 14 12 10 8 6 4 2 0 Act i ve Component s(s) Passi ve Component (s) I nt er connect ( s) I ndust r i al Tel ecom Comput er I ndust r i al Tel ecom Comput er Consumer Consumer Act i ve Passi v I nt er
Phase 1: Survey Solder Material Type 阶段 1: 调研 焊料类型 25 20 15 10 5 I ndust r i al Tel ecom Comput er Consumer 0 Pb- f r ee Lead free SnPb Pb-Sn
Phase 1: Survey Summary 阶段 1: 调研 总结 Creep corrosion was a common failure mode in the four product types mentioned in the survey. ( 在被调研的四类产品中爬行腐蚀是一种通行的失效模式 ) Most of the creep corrosion failures occurred in less than 3 years. Electrical shorting was the major failure mode. ( 大部分爬行腐蚀失效发生在三年内 短路是主要失效模式 ) Failures were reported globally. ( 全球都有报告爬行腐蚀的失效 ) Large number of responses correlated failures to air pollution levels/industrial areas. Some respondents correlated failures to high sulfur environments. ( 大部分失效发生在高空气污染和工业区 一些反映失效和高硫含量的环境有关 ) Some reported failures in indoor office areas. ( 有些报告失效产生于户内办公环境 )
The challenge 挑战 To develop a test that suppliers of Pb-free PCB assemblies can use to satisfy their customers that their products will survive environments high in sulfur-bearing gaseous contamination. ( 制定通用的实验方法对线路板组件进行测试以保证产品在一些高硫化环境中不失效 )
Phase 3: Investigation of Factors That Influence Creep Corrosion 阶段 3: 对爬行腐蚀的影响因素进行研究
Phase 3: Investigation of Factors That Influence Creep Corrosion 阶段 3: 对爬行腐蚀的影响因素进行研究 Perform laboratory-based experiments to investigate the affects of: ( 实验室的测试 ) surface finish, flux, solder mask geometry, solder paste coverage, reflow and wave soldering and mixed-flowing gas test conditions.
Test Plan 实验计划 Chamber Uniformity Test (3 runs) H 2 S = 1700 ppb; NO 2 = 200 ppb; Cl 2 = 20 ppb; SO 2 = 200 ppb; 40, RH 70-75%, 5 days H 2 S = 500 ppb; NO 2 = 200 ppb; Cl 2 = 20 ppb; SO 2 = 200 ppb; 40, RH 70-75%, 5 days H 2 S = 1000 ppb; NO 2 = 200 ppb; Cl 2 = 20 ppb; SO 2 = 200 ppb; 40, RH 70-75%, 5 days H 2 S = 1200 ppb; NO 2 = 200 ppb; Cl 2 = 20 ppb; SO 2 = 200 ppb; 40, RH 70-75%, 20 days Formal MFG Test (3 runs planned) H 2 S = 1200 ppb; NO 2 = 200 ppb; Cl 2 = 20 ppb; SO 2 = 200 ppb; 40, RH 70-75%, 20 days H 2 S = 1200 ppb; NO 2 = 200 ppb; Cl 2 = 20 ppb; To be determined SO 2 = 200 ppb; 40, RH 70-75%, 20 days
Chamber setup for mixed-flowing gas test 混合气体测试 (MFG) 实验箱
Cu corrosion rate, nm/day 混合气体实验箱中的腐蚀率 Corrosion rates in mixed-flowing gas chamber Ag corrosion rate, nm/day 1800 35 1600 1400 1200 1000 800 600 400 200 30 25 20 15 10 5 0 0 500 1000 1500 2000 Hydrogen sulfide, ppb 0 0 500 1000 1500 2000 Hydrogen sulfide, ppb
Corrosion product Cu coupon 腐蚀物 铜箔
MFG test matrix 1 st run MFG 实验矩阵 实验 1 H 2 S = 1200 ppb; NO 2 = 200 ppb; Cl 2 = 20 ppb; SO 2 = 200 ppb; 40, RH 70-75%, 20 days ID Finish Flux I-R ImAg (Immersion silver) Rosin flux I-O ImAg (Immersion silver) Organic acid flux O-R OSP (Organic solderability preservative) Rosin flux O-O OSP (Organic solderability preservative) Organic acid flux H-R Pb-free HASL (Hot air solder leveling) H-O Pb-free HASL (Hot air solder leveling) Rosin flux Organic acid flux
Creep Corrosion: Copper creep corrosion is when the corrosion products spread onto the solder mask beyond the edge of the pad or via. Heavy Creep (left picture) - Massive spread of corrosion products shorting signals. Light Creep (right picture) - Onset of creep signatures on the solder mask interface. Definition 名词 Corrosion: Corrosion product on the surface of the pad or via. But no spread of the material onto adjacent surfaces. Edge Corrosion: Corrosion products only along the edge of the pads. 18
MFG test result summary: 1 st run MFG 实验结果小结 : 实验 1 Finish and flux Corrosion Edge corrosion Creep corrosion Creep corrosion severity ImAg, organic acid flux Yes No Yes High ImAg, rosin flux Yes No No --- OSP, organic acid flux Yes No Yes Low OSP, rosin flux Yes No Yes Low Pb-free HASL, organic acid flux Pb-free HASL + rosin flux No Yes Yes High (isolated areas) No Yes No ---
Electrical short detection and resistance measurement 电短路和阻抗测量 PCB 20th day - Short Detected on the patterns of the TVs L1 L2 L3 L4 L5 L6 L7 L8 L9 L10 L11 L12 L13 1-I-R-1 1-I-R-2 1-I-R-3 1-I-O-1 4.7K Ω 38K Ω 3.55K Ω 1-I-O-2 600 Ω 48K Ω 1-I-O-3 1.5K Ω 9.8K Ω 1-O-R-1 1-O-R-2 1-O-R-3 1-O-O-1 1-O-O-2 1-O-O-3 1-H-R-1 1-H-R-2 1-H-R-3 1-H-O-1 36K Ω 1-H-O-2 1-H-O-3
ImAg, 20 days MFG, bottom side 化银,20 天混合气体测试, 底面 ImAg, rosin flux ImAg, organic acid flux
ImAg, organic acid flux, 20 Days MFG 化银, 有机酸洗免洗助焊剂,20 天 MFG Creep corrosion in the soldered and boundary areas
ImAg, rosin flux, 20 days MFG 化银, 松香助焊剂,20 天 MFG No significant creep corrosion. General tarnish.
OSP, organic acid flux, 20 days MFG OSP 镀层, 有机酸性免洗助焊剂,20 天 MFG
OSP, rosin flux, 20 days MFG OSP 镀层, 松香助焊剂,20 天 MFG Minor creep corrosion, non solder or flux location
Pb-free HASL, Organic Flux, 20 Days MFG 无铅喷锡, 有机酸性助焊剂,20 天 MFG Creep corrosion and edge corrosion due to poor HASL coverage
Pb-free HASL, rosin flux, 20 days MFG 无铅喷锡, 松香助焊剂,20 天 MFG No creep corrosion
Summary 总结 MFG test conditions of the 1 st formal run were chosen to reach the target of about 500nm/day copper corrosion rate. ( 调整 MFG 测试条件以达到铜箔腐蚀率约为 500nm/ 天 ) Creep corrosion was observed on all the finish types tested (ImAg, OSP and Pb-free HASL) ( 爬行腐蚀在测试的三种镀层中均有发生 ): However more creep corrosion was occurred on boards with organic acid flux. ( 使用有机酸性助焊剂的线路板产生的爬行腐蚀更多 ) Most severe creep corrosion was observed on ImAg boards with organic acid flux. ( 使用化银镀层和有机酸性助焊剂的线路板产生的爬行腐蚀现象最严重 ) Most serious creep corrosion locations have obvious flux residue. Most creep corrosion occurred in solder boundary area. ( 最严重的爬行腐蚀区域有明显的助焊剂残留 )
inemi Position Statement on the Limits of Temperature, Humidity and Gaseous Contamination in Data Centers and Telecommunication Rooms to Avoid Creep Corrosion on Printed Circuit Boards This position statement give recommended environment to avoid creep corrosion. Supporters: Gaseous contamination should meet the conditions of the modified severity level G1 of ANSI/ISA- 71.04-1985, Environmental Conditions for Process Measurement and Control Systems: Airborne Contaminants (ISA 1985): a copper reactivity rate of less than 30 nm /month, and a silver reactivity rate of less than 20 nm /month.
www.inemi.org Email contacts: Haley Fu haley.fu@inemi.org