Tsung-Hsiung Wang

Studies of Ni-B as an electrochemical metal migration barrier

The effectiveness of electroless Ni-B as a barrier metal to prevent the electrochemical migration between adjacent copper lines on a polyimide dielectric substrate was studied by measuring the resistance of the polyimide dielectric and by observing the electrochemical migration between the fine lines by reflective electron microscope after stress conditions. The rate-determining step associated with the electrochemical migration was also discussed.

Metallization of photosensitive epoxy

The adhesion strength of various photosensitive epoxies with copper or FR4 substrate was measured by the stud pull testing method. The adhesion strength was around 35-60 kg/cm 2 for photosensitive epoxy/copper laminate and 60-105 kg/cm 2 for photosensitive epoxy/FR-4 laminate. A high adhesion strength of metal/photosensitive epoxy can be obtained when the surface of photosensitive epoxy is subjected to 1 minute of microetching in the processes of metallization. Under such a processing condition, the adhesion strength of copper/photosensitive epoxy for Taiyo PVI-500/SA-50 can be as high as 145 kg/cm 2 , and the adhesion strength remained higher than 145 kg/cm 2 after the solder float test.