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A chip or die attachment process and related apparatus, in which a desired quantity of solder (7 or 17) is dispensed onto each, in turn, of a number of desired locations on a substrate (4 or 18), and then an integrated-circuit chip (10) is precisely positioned at each location immediately after the

A chip or die attachment process and related apparatus, in which a desired quantity of solder (7 or 17) is dispensed onto each, in turn, of a number of desired locations on a substrate (4 or 18), and then an integrated-circuit chip (10) is precisely positioned at each location immediately after the solder is dispensed at that location. Hot gas heaters are used both to heat the solder (7 or 17) as it is dispensed onto the substrate (4 or 18), and to heat the integrated-circuit chip (10) and to reflow the solder beneath the chip. In one form of the invention, the solder is dispensed from a wire spool (1) and melted in position on the substrate (4). Alternatively, the solder is dispensed as a drop (16) from a liquid solder reservoir (13).

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1. 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 disp

1. 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. 2. A process as defined in claim 1, wherein the step of heating the end portion of the wire is performed by directing a flow of heating gas onto the end portion of the wire from at least one hot gas injection system.3. A process for attaching integrated-circuit chips to a substrate by soldering, the process comprising the steps of:dispensing a precise quantity of solder in solid wire form from a wire spool; feeding the wire solder toward one of a plurality of desired locations at which integrated-circuit chips are to be attached to a substrate; holding an end portion of the solder wire in the desired location; simultaneously heating the end portion of the wire with hot gas from a hot gas injection system, to melt the end portion and write the desired quantity of solder onto the desired location; immediately after the desired quantity of solder is written onto the desired location, precisely placing an integrated-circuit chip over the quantity of solder at the desired location; heating the integrated-circuit chip, and with it the underlying quantity of solder, with hot gas from at least one hot gas injection systems; reflowing the quantity of solder beneath the integrated-circuit chip, as a result of the step of heating the chip, 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 other integrated-circuit chips are to be attached, whereby chips may be positioned in close proximity to each other for improved performance at high frequencies. 4. A process as defined in claim 3, wherein the solder is an alloy of metals including gold.5. A process for attaching microwave or millimeter-wave integrated circuit (MMIC) chips to a substrate, the process comprising the steps of:dispensing a precise quantity of solder in solid wire form from a wire spool, wherein the solder is an alloy of metals including gold; feeding the wire solder toward one of a plurality of desired locations at which MMIC chips are to be attached to a substrate; holding an end portion of the solder wire in the desired location; simultaneously heating the end portion of the wire with hot gas from a hot gas injection system, to melt the end portion and write the desired quantity of solder onto the desired location; immediately after the quantity of solder is written onto the desired location, precisely placing a MMIC chip over the quantity of solder at the desired location; heating the MMIC chip, and with it the underlying quantity of solder, with hot gas from at least one hot gas injection systems; reflowing the quantity of solder beneath the MMIC chip, as a result of the step of heating the chip, 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 MMIC chip and the substrate; and repeating all of the foregoing steps in sequence at each of the desired locations at which other MMIC chips are to be attached, whereby MMIC chips may be positioned in close proximity to each other for improved performance at high frequencies.