Electro-Chemical Migration

The current industry standard test protocols were originally developed to identify highly ionic contaminant levels (halides) after a cleaning process.  Various forms of corrosion and ECM damage resulting in field failures on products that passed the current cleanliness and corrosion resistance test protocols has demonstrated that these test procedures are not completely effective. The current industry excepted testing does not take into consideration various acceleration factors associated with no clean flux and product design features.

This project was designed to create and evaluate the failure mechanisms, identify the gaps in the existing test methods, and identify modifications to the test methods required to predict where a failure will likely occur. The project collected and evaluated test data and drafted proposed changes to existing test methods, test protocols and the IPC and JEDEC specs.

 

 

Project stage: 
Lead company: 
Kyzen

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Idea Information

Background: 

 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.

2. The failure mechanism is the same regardless what segment of the electronics industry the PCBA is used.
 
3. The current testing does not take into consideration various acceleration factors associated with no clean flux and product design features.
 
4   Pitting/Crevice corrosion has been detected on field failed boards
Boards were soldered with a no-clean wave or selective soldering flux
The failure is an open surface type corrosion event
Occurs on boards exposed to
      • Harsh environments
      • Atmosphere pollutants

 

  • High humidity levels
Problem: 

 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.

 

Intermittent defects in soldermask provide potential failure locations
May expose a copper trace
Wave and Selective Solder Processes
Deposit liquid flux over the surface being soldered
No-Clean processes
Flux residue is not removed after soldering
Flux is formulated to have a non-ionic (benign) residue
The problem
Active flux can be wicked into openings or flaws in the soldermask
Active flux can propagate corrosion onto exposed metals
Ions from the flux residue can be mobilized with atmospheric moisture
 

 

Definition Information

Goals / Benefits: 
The objective of this project is 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.
This project will focus on the failure mechanism during this phase of the project. It was determined early on that we would have to have a follow-on project to determine the best test method to identify the material failures.
High level objectives: 
 
Approach: 
  • 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 DOE’s to validate proposed changes
    • Perform DOE’s. 
    • 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

 

 

 

 

 

 

 

 

 

Key Participants: 
Celestica
Ciena
Cisco
Dell
Engent
Flex
Fujitsu
Huawei
IBM
Indium
Isola Group
Juniper
Keysight Technologies
Kyzen
Nihon Superior
NVIDIA
Oracle
Panasonic
Park Electrochemical
Plexus
Sanmina
Senju Comtek
Shengyi
TTM Technologies
Public