How to improve void performance in wafer bumping

Void of solder joint can be considered to be one of the main defects in electronic assembly. The existence of void will influence not only the reliability of solder joint, but also the electrical, mechanical and thermal properties of solder joint. X-ray is the traditional method to analyze solder void. The inspection criteria to void are subjective, different customers have different requirements to the void performance of the product. Although the theory of forming void is known, different cases need different actions to get optimized void performance. The main objective of this paper is to study how much the application process can impact the void performance independently. The process parameters investigated in this study mainly include printing parameter effect, reflow profile effect and heating mechanism effect on void formation of solder joint.