Calculation and Optimization of the Filler Quantity Used in Brazing Ceramic Package

The leadframe and sealed ring made of 4J42 alloy were brazed in hydrogen furnace by AgCu28 brazing filler with metallized alumina substrate whose surface was electroless nickel plated in advance in ceramic DIP manufacture. However the liquid filler often overflowed onto the surface of the leadframe and the sealed ring, and the quality of the finished products would be influenced greatly. These problems were related to the filler quantity used in brazing ceramic package. The brazing test for ceramic package was carried out by using different filler quantity, and the influence on flowing of the filler was studied in the present paper. The actual filler quantity was calculated and the optimum range of 38～55μm for the filler thickness on the surface of the brazing zone was given.