Project Statement (Version 2.0, October 12, 2009) (initial sign up ended November 11, 2009)
Creep
corrosion is a mass transport process in which solid corrosion products (typically sulfide and chloride) migrate over a surface without the influence of an electric field. Creep corrosion is highly surface-specific and a given corrosion product can only migrate on a specific type surface. Recently, creep corrosion has been observed on printed circuit boards with lead-free surface finishes such as ImAg and OSP. In this case, the corrosion product (typically copper sulfide) "creeps" onto the solder mask surface and causes short circuits between the adjacent pads and traces. Creep corrosion on printed circuit boards is promoted by the residue of certain types of fluxes.
Laboratory simulation must take the highly surface-sensitive nature of creep corrosion into consideration. Mixed flowing gas (MFG) testing can simulate the environmental conditions in the global marketplace and has been successfully used to generate creep corrosion on electrical contacts (metallic surface) and IC components (dielectric surface). Creep corrosion can also be reproduced on printed circuit boards using MFG test. The MFG test provides a viable and realistic accelerated aging test for creep corrosion. However, it is also reported that the conditions of the current MFG corrosion resistance test method are unable to predict product life and reproduce the failure mechanisms observed in real world environments.
This project will:
Collect the data on creep corrosion failures and related factors in the electronics industry
Analyze and understand the root cause(s) of creep corrosion
Develop an industry acceptable test method to assess the development of creep corrosion in the field environment
For additional information: Haley Fu +86 21 5835 3839 haley.fu@inemi.org
