Flux-free photodetector bonding
AssigneeRCA Corporation
InventorFrank Z. Hawrylo
Life of this patent
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Abstract
A method of bonding photodetector devices to heatsinks, which devices can be damaged above 250.degree. C., using a gold-tin eutectic solder which has a melting point of 280.degree. C., is disclosed. The process comprises heating the heatsink and solder past the solder melting point on a quick thermal response heating element, turning off the heating power, and introducing the chip into the liquid solder on the cool down cycle. By controlling the rate at which the heatsink solder and device cool down and the time span from introduction of the chip to solidification of the solder, the chip can be exposed to sufficient heat to provide a good thermal, electrical and physical bond while substantially enhancing the yield of electrically undamaged photodetector chips.
Claims9
A method of soldering a semiconductor device to a heatsink wherein said device has a critical temperature above which it is adversely affected and wherein the solder has a melting temperature above said critical temperature, which method comprises;
- heating the heatsink and the solder above the solder melting point;
- cooling the liquid solder situate on the heatsink;
- introducing the device into the liquid solder under a pressure sufficient to provide uniform heating and wetting of the device by the solder;
- and
- controlling the time span and cooling rate between the device introduction step and the point at which the solder solidifies whereby an acceptable electrical and thermal bond of the device to the heatsink is provided with minimal adverse effects to the device.
Dependencies are inferred from the claim text.