Abstract
With the leap into the 5G era, the demand for improvements in the performance of mobile phones is on the rise. This is also true for the quantity of radio frequency (RF) front-end integrated circuits (ICs), especially for RF switches and low noise amplifiers (LNA). It is well-known that improvements in performance depend on the combination of new design, package technology, and choice of materials. Ultra-low residue (ULR) flux is an innovative, truly no-clean, flip-chip bonding material. By using ULR flux, the typical water-wash cleaning process can be removed and, in some instances, package reliability can be improved as well. This simplified assembly process will help to reduce total packaging costs. This paper will discuss the application of ULR fluxes on land grid arrays (LGAs) and quad-flat no-leads/dual-flat no-leads (QFN/DFN) packages for RF front-end ICs, as well as the reflow process. The solder joint strength and reliability study will be shared as well.
