Influence of ceramic substrate quality on CBGA assembly reliability

Abstract

The highly air-sealed ceramic ball grid array (CBGA) package is more and more popular in the aerospace and other military industries, the quality of its ceramic substrate can largely determine the CBGA package reliability and further product performance. Thus, two kinds of high temperature co-fired ceramic (HTCC) substrates from A and B suppliers were employed to assess different CBGA assembly performances in this work. The results were found that the pads of A and B substrates owned similar morphology feature and mean size. After re-balling process, comparing to that of B substrate, the mean deviation from coplanarity of A substrate was higher, but the shear strength of solder balls on A substrate was better and more stable. Through analyzing shear fracture faces, the dimples were discovered and ductile fracture mode was verified. Additionally, the microstructure of CBGA package was observed after soldering process, the metallurgical reactions at solder joints occurred and the interfacial intermetallic compound (IMC) layers formed. When 100 cycles test from −55 to 85 °C finished, the metallographic analysis was obtained that the solder joint in the corner of CBGA package produced deformation and microcracks due to high thermal stress, the microcrack result was better with the usage of A substrate. The series of detection methods and means might provide the effective help for CBGA engineering application.