Placing Solder Terminals on Silicon Wafers
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Jan-31
An extrusion method has been developed for close control of solder composition and its placement on semiconductor wafers. Instead of a conventional evaporation method, solder, with a composition identical to the composition of the starting bulk alloy, is extruded through a mask opening used for placement of the solder on the ball limiting metallurgy (BLM) pads on the wafer. In the proposed method, solder 1 (Fig. 1) is placed in a metal block 2. A piston 3 is used to extrude the solder through holes in (Image Omitted) three plates 4,5,6. A support plate with windows 7 is used to receive excess solder. The extrusion may be done at room temperature, or the device may be heated to lower the viscosity of the solder.