TWO-PIECE Pb/Sn CUP WITH LINER
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
Lining of Ta cups used for Pb/Sn evaporation in semiconductor manufacturing processes is a means of eliminating spitting which occurs with unlined cups. During Pb/Sn evaporation there is an apparent formation of a Ta/Sn bimetallic which occurs at the final stages of source evaporation. This residue results in excessive spitting which causes chip defects and partial pads. A pyrolytic, boron-nitride liner 1, as shown in the drawing, is placed inside the Ta cup 2 which has its top 3 secured by ring clamp 4. With only liner 1 contacting the Pb/Sn evaporation source there will be no spitting, since the Ta contact with Sn has been eliminated. The two-piece construction means that new liners may be inserted into Ta cups as required.