With the driving force of “green” revolution inelectronics industry, tremendous efforts have been put on looking forlead-free alternatives. Although lead-free alloys draw a lot ofattention, their parasitic weaknesses, such as high processingtemperature and surface tension, limit their application on thermallysensitive, flexible, non-solderable substrates and ultra-fine pitch sizeflip chip interconnection. Conventional electrically conductiveadhesives (ECAs) have been widely used in surface mount and die-attachtechnologies for electrical interconnection and heat dissipation. Lowprocessing temperature of ECAs is one of the major advantages overlead-free solders, which brings low system stress, simple manufactureprocess and the like. In order to improve the contact resistance ofECAs, the low melting point alloy (LMA) incorporating technology hadbeen developed by our group. In this paper, the research thrust wasconcentrated on the LMA depletion method since re-melting LMA in ECAscan adversely affect the physical property. A differential scanningcalorimeter (DSC) was used for the basic examination of depleting rateof LMAs in the typical ECAs. Cross-sectional morphology was investigatedby scanning electron microscopy. A new curing process was designed todeplete the LMA in ECAs. Providing enough time for LMA to wet on thesurface of silver and metal pad could improve the contact resistance onnon-noble metal pad during high temperature and humidity test
展开▼
