Statement of Work and Project Statement 

• Statement of Work (Version 3.4, November 30, 2010)
• Project Statement (Version 3.4, November 30, 2010) (initial sign- up ended February 18, 2011)

Background / Previous Work

iNEMI began a phased approach to investigate creep corrosion in October 2009. Phase 1 consisted of a survey to collect the data on creep corrosion failures and related factors in the electronics industry (download survey results). The team also communicated with ASHRAE, IPC 3-11g and Lawrence Berkeley National Laboratory on related issues. In Phase 2, the team analyzed the output from Phase 1 and narrowed down the major factors that influenced creep corrosion.

Phase 3 performed laboratory-based experiments to further investigate the sensitivities of the influencing factors, including surface finish, flux, solder mask geometry, solder paste coverage, reflow and wave soldering, and mixed flowing gas (MFG) test conditions (corrosive gas concentration, humidity, temperature).

The team believes more experiments, based on previously published work, could help:

• Understand the sensitivities of the already identified contributing factors
• Validate the effectiveness of a few mitigation approaches
• Correlate experimental test conditions to environment classification standards (e.g. ISA G1, G2, etc.)

Testing to date has used ImAg, OSP and Pb-free HASL-finished boards with reflowed Pb-free solder paste on the top side of the test vehicle and wave solder on the bottom side — some with no-clean organic acid flux and others with no-clean rosin-flux. Boards were subjected to a mixed-flowing gas environment with gaseous composition adjusted to achieve the targeted 500-600 nm/day copper corrosion rate.

Results were as follows:

• Copper creep corrosion was observed primarily on the ImAg- finished boards that were wave soldered with no-clean organic acid flux.
• Pb-free HASL-finished boards experienced some severe but localized creep corrosion due to exposed copper metallization.
• Creep corrosion was most severe in the wave soldered boundary areas where no-clean organic acid flux residue was present.

The initial investigation into causes of creep corrosion gave rise to a second series of projects focused on developing a cost-effective and reliable creep corrosion qualification test, and these projects led to development of a highly effective flowers-of-sulfur (FOS) test chamber. (See Qualification Test Development for Creep Corrosion, Phase 1.)

Papers & Presentations

• End-of-Project Webinar - Presentation (November 5, 2012) This presentation is for iNEMI members only
• iNEMI Study on Board Creep Corrosion, presented by Haley Fu (iNEMI) at the CEEDI (China Electronics Engineering Design Institute) Technical Seminar on Data Center IT Equipment Corrosion by Gaseous Contamination and Measures (Beijing, China; April 24, 2012).
• iNEMI Position Paper: 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 (April 21, 2012)
• iNEMI Experimental Investigation on Creep Corrosion, presented by Haley Fu (iNEMI) at ICEP-IAAC 2012 (Tokyo, Japan; April 19, 2012).
• Investigation of Factors That Influence Creep Corrosion (session keynote), Haley Fu (iNEMI), P.J. Somgh and Jing Zhang (IBM Corporation), Anil Kurella (Intel Corporation), Xu Chen and Xiaodong Jiang (Alcatel-Lucent), Jennifer Burlingame (Cisco); presented by Prabjit Singh (IBM), SMTA Pan Pacific Microelectronics Symposium, February 14-16, 2012, Kauai, Hawaii. presentation    paper
• Investigation of Factors that Influence Creep Corrosion, presented by Cherie Chen (IST), iNEMI session at IMPACT 2011 (International Microsystems, Packaging Assembly and Circuits Technology), NTUH International Convention Center, Taipei, Taiwan, October 21, 2011
• Phase 1 Survey Report (December 2009)

For Additional Information

Haley Fu
haley.fu@inemi.org