Interfacial Issues Of Lead-free Interconnection And RFID Fabrication

Traditional SnPb solder will be abandoned gradually with the voice of appealing forgreen environment from public, pressure of the lead-free legislations from eachgovernment and increasing requirements of higher qualities. The research on lead-freeelectronic packaging materials and technologies has become one of the most importantareas in current electronic packaging industry. With the increase of multi reflow times, the thickness of interfacial intermetalliccompound (IMC) increases significantly and a phenomenon of IMCs spalling fromIMC/Ni interface is observed. As a result, the shear strength of SnAgCu/Ni solder bumpdecreases significantly. The reason of IMC morphology and dimension differencesbetween center and brim of bump interface is the different compositions of IMC in variousareas caused by different concentration of Cu in the interfacial reaction of multi reflows. The interfacial IMC thickness of Sn3.5Ag/Ni and Sn0.7Cu/Ni solder bump increaseslinearly with the square root of thermal aging time. Interfacial IMC of SnAg/Ni growsslower than that of SnCu/Ni in aging experiment which is caused by the dispersion ofAg3Sn phase. With the increase of heating factors, meaning thickness of interfacial IMC increasesunder an exponential law. There are 3 phases in the growth period of interfacial IMC withthe increase of heating factors. A heating factor of about 800~1000 sec?°C isrecommended to be a better choice for acquiring higher productivity and interfacialreliability. Interconnection of RFID chip with antenna is achieved by conductive adhesivetechnology, which is a kind of non-solder interconnections. A concept of modularmanufacturing is presented and applied as a utility model patent.