The Brazing Reliability of the Co-fired Multilayerd Ceramic Substrates

The effects of the W metallizing condition and silver brazing condition on the bonding reliability of the nail head lead pins of the multilayer ceramic substrates manufactured by co-firing was examined. High bonding strength by the silver brazing to the W metallized layer was obtained when the W metallizing layer was 23 μm thick or thicker and the quantity of the silver solder used was 0.24-0.38 mg/mm2 and the silver brazing temperature was 820-840°C. The bonding strength by the silver brazing was decreased after the brazed parts were heat-treated at 900°C. The cause of the degradation of the bonding strength was that the silver solder permeates into the W metallized layer and destroys the network of the W in that layer.