Electro-Chemical Migration 2
In our previous project Electro-Chemical Migration we found that a No Clean Flux, which is designed to leave a benign residue, can result in crevice and pitting corrosion. We also discovered the flux activators can remain on the board due to excessive flux or entrapment (ie,: Selective solder fixtures, Wicking into soldermask and Non solder mask defined pads). We already knew that harsh environments subjects devices to high humidity. This all means that Ions can be mobilized and cause corrosion on exposed copper features. In this follow-on project we would like to develop a Test Method for determining Pitting / Crevice Corrosion capability of a Solder Flux. We then would submit the method to IPC Cleaning and Coating Committee for consideration of an additional test within J-STD 004 to evaluate flux potential to propagate Pitting / Crevice Corrosion capability of a Solder Flux on Cu and Sn and subsequently work with the IPC Committee on Cleanings and Coatings to implement our recommendations.
If you are interested in participating in this project:
Members - Go to the "Subscribe Here" section to the right and select the "Subscribe to space" key.
Non Members - Go to the "Contact" section to the right and select the "Contact project facilitator" key.
From previous experience it is currently accepted that "Activity of flux is one of the important aspects in circuit reliability". As such our thinking is that we would like to:
- Examine CuOx dissolution in flux solutions on Cu substrates using electrochemical methods
- Potentiometry and Gravimetric analysis
- Sn2+ and Sn4+ can form Sn-carboxylate complete and dissolve into solution