Thermomechanically loaded lead-free LGA joints in LTCC/PWB assemblies

Purpose – The purpose of this paper is to investigate the feasibility of using land grid array (LGA) solder joints as a second‐level interconnection option in low‐temperature co‐fired ceramic (LTCC)/printed wiring board (PWB) assemblies for telecommunication applications. The characteristic behaviour of two commercial lead‐free solder materials (Sn4Ag0.5Cu and Sn3Ag0.5Cu0.5In0.05Ni) in reflow processes and thermal cycling tests are also evaluated.Design/methodology/approach – The effect of the reflow temperature profile on voiding in two lead‐free solders in LTCC/PWB assemblies was investigated using X‐ray and scanning electron microscopy (SEM) investigations. The test assemblies were fabricated and exposed to a temperature cycling test (TCT) in a 0‐100°C or −40 to 125°C temperature range. Organic PWB material with a low coefficient of thermal expansion (CTE) was primarily used. In addition, to compare LGA assemblies with low and high global thermal mismatches, an LTCC module/FR‐4 assembly was also fabric...

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