Much of the Assembly industry has experienced the effects of Electro-Chemical Migration. It has been shown that contaminants on the surface of PCBs can migrate and cause creep corrosion and/or shorts. This occurs primarily on the newer Pb free surfaces/finishes. It is thought to be driven by changing geometry, surface finishes and board cleanliness.
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1. Various forms of corrosion and Electro Chemical Migration failures on products that pass the current cleanliness and corrosion resistance test protocols have demonstrated that these test procedures are not effective.
- Harsh environments
- Atmosphere pollutants
- High humidity levels
The current industry standard test protocols were originally developed to identify highly ionic contaminant levels (halides) after a cleaning process. These test protocols are not completely effective at identifying ECM exposures from no-clean flux residues.
To identify the required enhancements to the current industry specifications, test methds and coupon designs, to midigate the Electro-Chemical Migration and corrosion induced failures when no-clean fluxes are used.
- Planning Steps: 9/12/12
- List current test methods / etc.
- List failure modes
- Correlate failures to gaps in test methods
- Identify modifications required to test methods
- Develop DOEâs to validate proposed changes
- Perform DOEâs.
- Collect and evaluate test data
- Draft proposed changes to test methods / etc.
- Provided proposed changes and supporting data to IPC, JEDIC, etc.
- Write final report