Patent ID: 6945447

Claim:
A die attachment process for attaching integrated-circuit chips by soldering to a substrate, the process comprising the steps of: dispensing a precise quantity of solder onto a substrate at one of a plurality of desired locations at which chips are to be attached; immediately after the solder dispensing step, precisely placing a chip over the quantity of solder at the location; heating the chip, and with it the underlying quantity of solder, with hot gas; reflowing the quantity of solder beneath the chip, as a result of the heating step, to form a continuous layer of solder between the chip and the substrate; allowing the solder to cool, to complete a reliable electrical and thermal bond between the chip and the substrate; and repeating all of the foregoing steps in sequence at each of the desired locations at which components are to be attached, whereby chips maybe positioned in close proximity; wherein the step of dispensing a precise quantity of solder includes: dispensing the solder initially in solid wire form from a wire spool; feeding the wire solder toward the desired location on the substrate; holding an end portion of the solder wire in the desired location; and simultaneously heating the end portion of the wire with hot gas, to melt the end portion and write the quantity of solder into the desired location.