3D Wafer Level Compression Molding Process Development For Image Sensor Package

For CMOS image sensors (CIS), automotive application is a very big market. However, it is quite difficult for the package especially WLCSP to pass the automovive reliability requirement. In this paper, a highly reliable wafer level image senor packaging technology using wafer level molding process was reported. Various related materials and process such as die to wafer attach, compression molding, de-flash, laser dicing are investigated. The controlling of the exposure height of the solder balls after molding process is a big challenge since it may have relationship with release film material, molding parameters, ball pitch and ball diameter. Experimental for warpage reduction, chip crack prevention, and residue cleaning on solder ball by de-flash process are carried out. Reliability tests based on JEDEC standard are carried out to study the package reliability. The results show there is no failure for the test samples using present package structure.