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Selectively Arc Spraying Metal On Graphite Fins For Solderability

IP.com Disclosure Number: IPCOM000012874D
Original Publication Date: 2003-Jun-05
Included in the Prior Art Database: 2003-Jun-05
Document File: 1 page(s) / 47K

Publishing Venue

IBM

Abstract

Graphite heat sinks have low cost and high thermal performance. The challenge is to fabricate large size graphite heat sinks with flat thermal faces. One graphite heat sink design that has been proven feasible uses copper heat sink base and graphite fins. The graphite fins are made solderable by arc spraying them with a metal layer. The metal coated graphite fins are soldered into slots in the copper base. The problem is that the graphite fins are quite fragile for the arc spraying operation that involves grit blasting followed by arc spraying. In addition, the present state-of-the-art arc spraying process is very expensive. This invention solves this problem by using a fixture that protects the fins during the arc spray coating process and makes the process more cost effective.

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Selectively Arc Spraying Metal On Graphite Fins For Solderability

   The proposed invention comprises a fixture that holds multiple graphite fins. The ability to coat many fins at once makes the process more cost effective. The fixture protects the fins during the arc spray process and masks the fins so that only the area to be soldered is metal coated.

     The invention comprises a fixture as shown above. The fins are stacked in a staggered manner on the base plate. To avoid bending the stacked fins, end incline planes are used that support the fins near the two ends. The stack of fins is held down using multiple metal bars that are padded with a rubber-like material that presses the fins down without damaging them. The metal bars apply downward pressure on the fins by means of spring loaded bolts.

     To coat the other side of the fins, the fin stack is rearranged to expose the other side of the fins.

     The fixture protects the fins by supporting them between a metal base plate and multiple metal bars that are padded with rubber-like material. Only the portion of the fin to be soldered is exposed to arc spray. Multiple fins can be coated simultaneously, increasing the throughput.

Disclosed by International Business Machines Corporation

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