CERAMIC CIRCUIT BOARD BACKED AT LOW TEMPERATURE

摘要

PURPOSE: To improve the reliability of an Ag-Au junction part and to simplify the process. CONSTITUTION: A via-hole 13 is formed in a green sheet 12 containing 60 pts.wt. of CaO-SiO2 -Al2 O3 -B2 O3 glass powder and 40 pts.wt. of alumina powder. After the via-hole 13 is filled with Ag conductor paste (via) 14, a wiring pattern 15 of the same Ag conductor is printed. After a plurality of the green sheets 12 are stacked and thermally compressed, they are backed at a low temperature to prepare a ceramic board 11. Thick paste of an Ag/Pd layer 16 is printed in an exposed part of the via 14 of an Ag conductor of a surface of the ceramic board 11, a wiring pattern 17 of an Au conductor is printed thereon and it is baked simultaneously. It is preferable to incorporate 100 pts.wt. of a metallic component consisting of 70 to 95 pts.wt. of Ag and 5 to 30 pts.wt. of Pd powder, 2 to 10 pts.wt. of borosilicate glass powder and organic vehicle in a paste composition of the Ag/Pd layer 16.