Selective laser sintering of aluminum nitride for microelectronics packaging

The purpose of this research is to develop a method to produce aluminum nitride parts for multichip module packaging by the rapid prototyping method of selective laser sintering. Aluminum nitride is desirable for this application because it has a high thermal conductivity, electrical insulating properties that extend to high frequencies and is a thermal expansion match for silicon and gallium arsenide. The SLS process can quickly and easily build extremely complex parts, making it ideal for producing a wide range of parts for electronic packaging.; The main problem with using SLS to produce aluminum nitride parts lies in the melting point of the material which does not melt but dissociates at 2,227°C and 1 atm. This can be overcome by using a lower melting point material to bind the aluminum nitride particles together. Two materials were chosen as binders: aluminum and a polymer binder used by the DTM Corporation to bind stainless steel in RapidSteel® 2.0.; The use of aluminum as a binder resulted in severe curling of the part layers during the SLS process. This problem can be overcome but would require an SLS machine with the capability to heat the part bed to a temperature of 660°C. Since the machine used can only heat the part bed to 150°C, no good parts could be produced using the aluminum binder.; Good parts were produced using the DTM binder. Various tests were performed to find the optimum parameters and powder concentrations for this process. The issue of post processing still needs to be addressed. This involves burning the binder out of the part and infiltrating the void with a suitable material.