In order to meet the demand of fine pitch and 3D package, and eliminate complex underfilling process, a first solder joint encapsulant has been invented. Solder joint encapsulant adhesive is to encapsulate each individual solder joint using polymer to enhance solder joint, and leave empty space in-between solder joints to avoid thermal stress applied onto solder joints. Now two kinds of solder joint encapsulants are SMT256 and SMT266, which have been used in the customer field. Using solder joint encapsulants – SMT256 and SMT266, the pull strength of solder joint has been increased by about five times, resulting in significant increase in the reliability. In this paper more details have been investigated.

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