Verification of flip‐chip assembly on FR4 boards

Abstract

As a result of the trend towards portable communication products, low‐cost miniaturisation is becoming increasingly important. One of the methods to achieve low‐cost miniaturisation is flip‐chip assembly on FR4 boards. In this paper, two types of flip‐chip assembly process will be discussed: a process where flip‐chips with eutectic solder‐bumps are assembled by using a tacky flux, and a process where flip‐chips are assembled by using solder paste. Both processes have been verified on production boards, using production equipment. Demonstrated ppm defect levels are between 35 and 400 ppm (confidence level 95 per cent) at the solder joint level. Component yields for flip‐chips are between 99.2 and 100 per cent. The reliability of the assemblies fulfils consumer communication equipment requirements.