Transition to Pb-free manufacturing using land grid array packaging technology

Land grid array IC-packages are gaining popularity among portable electronics, for low cost, mechanical reliability, direct Pb-free assembly process compatibility, and their low profile on the PWB. LGA technology is an excellent choice to fulfil future environmental requirements in thin and compact products. The reliability performance of 0.5 mm pitch LGA structure is compared to ball grid array (BGA). Reliability performance is evaluated through comparative tests designed for a portable environment. These tests consist of temperature cycling test for operation performance evaluation and board level drop test for mechanical shock durability performance evaluation. The stress distributions in LGA and BGA are analysed by the finite-element method (FEM). Furthermore, reliability investigation is done for LGA components using both standard SnPb- and Pb-free assembly processes. The differences in the reliability performance between the SnPb- and Pb-free assemblies are explained through microstructural analysis. Reliability issues relating to the transition from conventional assembly process to Pb-free process are discussed, based on the test and simulation results.