Reflow-oven-processing of pressureless sintered-silver interconnects

A method was developed to pressurelessly fabricate strong and consistent sinterable-silver joints or interconnects using reflow oven heating. Circular sinterable-silver interconnects, having nominal diameter of 5 mm and 0.1 mm thickness were stencil printed, contact-dried, and then pressurelessly sinter-bonded to Au-plated direct copper bonded ceramic substrates at 250 °C in ambient air. That sintering was done in either a reflow oven or a convective oven (latter being a conventional heating source for processing sinterable-silver). Consistently strong (>40 MPa) interconnects were produced with reflow oven heating and were as strong as those produced with convective oven heating. This is significant because reflow oven technology affords better potential for continuous mass production and it was shown that strong sintered-silver bonds can indeed be achieved with its use.