Optimizing technological process for laser soldering of fine-pitch flip chips

In the frame of EC sponsored RTD projects as well as industrially requested innovation developments the activities of BME-ETT cover the full technology of electronics design, assembling, soldering, process monitoring and testing. This paper presents some important details how a team of BME-ETT has been developing and optimizing the solder paste printing, component placement and laser soldering sequence of processes to assemble flip-chips with 80 mum size bumps onto a polymer substrate with 200 times 200 mum size pads. In particular, the problems and solutions of working out the stencil printing, chip placement, and their testing methods are illustrated and explained in the paper.