Si based print circuit board fabricated by si deep etching and metal powder injection molding

In this report, Silicon wafer based print circuit board is presented as an example of application of this technique, where the metal was filled into ICP fabricated through holes to make electrical feed through. The target application of this work is Silicon based print circuit board. The electrical feed through was fabricated by casting the Ag (80 wt%) + Cu (20 wt %) mixed with binder into the small diameter through holes in oxidized Silicon wafer. A multi-component binder system comprising of EVA (Ethylene Vinyl Acetate 35 wt%) + PW (Paraffin Wax 65 wt%) was used. Super critical debinding method is applied prior to final sintering process. The ratio of metal powder and binder was 9:1. SEM observation shows that the through holes are filled with metal powders. Conventional debinding process resulted in scattering the metal powder onto the Si wafer during debinding process and final sintering process. Very slow temperature elevation heating and super critical debinding process resulted in good formation of electrical feed through. The feed through formed with small bumps because of expansion of the metal powder area. The electrical conductivity test was sufficient between top and bottom. Several Feed through formation methods have been proposed. The electroplating and vacuum casting method are well known processes. Compared with these methods, this is rather rapid and economical, and provides desired shape of bumps and no need of eliminating the unnecessary part.