A Test Method to Determine the Degree of Embrittlement in Electrodeposited Copper

The brittle fracture of copper conductors in printed circuits is a severe problem in the electronics industry because such fractures will cause open-circuit conditions to occur in completed assemblies where the contributed value is high. In addition, repair possibilities may be limited due to the complexity of the assembly at the time that failures are discovered.

This paper deals with the development of a test method that is useful for the detection of an embrittled condition in foil prior to its application in circuits. Through the use of the mini-cup test method, a ductile-to-brittle transition was discovered, and, through further study of the transition phenomenon, procedures have been suggested for the characterization of electroplated copper foil.