Warp-resistant heat sink

• US 4,009,752 A
• Filed: 02/24/1975
• Issued: 03/01/1977
• Est. Priority Date: 02/24/1975
• Status: Expired due to Term

• Current Assignee: Honeywell Information Systems, Inc. (Honeywell International Inc.)
• Original Assignee: Honeywell Information Systems, Inc. (Honeywell International Inc.)
• Inventors: Wilson, Edward Arthur
• Primary Examiner(s): Davis, Jr., Albert W.
• Application Number:
  US05/552,494
• Time in Patent Office: 736 Days
• Field of Search: 165/185, 165/183, 165/81, 165/182, 317/100, 357/81
• US Class Current: 165/81
• CPC Class Codes: H01L 23/3672 Foil-like cooling fins or heat sinks being part of lead-frames H01L23/49568
• CPC Class Codes: H01L 23/3736 Metallic materials H01L23/3732, H01L23/3733, H01L23/3735, H01L23/3737, H01L23/3738 take precedence
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: Y10S 165/051 having expansion and contraction relieving or absorbing means

Abstract

A warp-resistant heat sink suitable for soldering to one side of a relatively fragile, ceramic semiconductor substrate comprises a plate of heat-conducting material having a plurality of slits along two sides thereof, and a plurality of U-shaped heat-conducting members each of which extends through a respective one of the slits in the plate. The U-shaped heat-conducting members are soldered to the same side of the plate, the members along one edge of the plate being off-set with respect to the members along the opposite side of the plate in order to increase the heat transfer efficiency when air is forced through the heat sink. The plate material is selected so as to have a substantially identical thermal coefficient of expansion as that of the substrate material. When the heat sink plate is soldered to the substrate surface, a laminate is thereby formed comprising two outer layers of material having substantially identical thermal coefficients of expansion and an inner layer having a different thermal coefficient of expansion. Relatively large heat sinks can thus be fabricated which have a high resistance to the warpage which would otherwise result from the dissimilar thermal expansion and contraction of the ceramic substrate and the heat-conducting members.

Claims

1. A warp-resistant heat sink suitable for soldering to a relatively fragile, ceramic semiconductor substrate, wherein said heat sink comprises

a rectangular heat-conducting plate having a plurality of slit-like openings along opposite edges thereof, said openings being normal to the edges, the openings along one edge being offset with respect to those along the opposite edge, said plate having a thermal coefficient of expansion substantially identical to that of said ceramic substrate;

a plurality of U-shaped heat-conducting members, each of said members extending through a respective one of said openings in said plate, the members which extend through the openings along one edge of said plate all having an identical orientation and the members which extend through the openings along the opposite edge of said plate all having an identical orientation, the orientation of the members along one side being different from that of the members along the opposite side, one side of each of said members being secured to the same side of said plate, said members being formed of material having a different thermal coefficient of expansion than said plate, whereby when said heat sink plate is soldered to said substrate the laminate thereby formed comprises two outer layers of material having substantially identical thermal coefficients of expansion and an inner layer having a different theremal coefficient of expansion.

2. The heat sink according to claim 1, wherein said plate is comprised of Kovar, and said members are comprised of copper.

3. An air-cooled heat sink, comprising

a rectangular plate having a plurality of slit-like openings along opposite edges thereof, said openings being normal to the edges, the openings along one edge being offset with respect to those along the opposite edge;

a plurality of U-shaped heat-conducting members, each of said members extending through a respective one of said openings in said plate, the members along one edge all having an identical orientation and the members along the opposite edge all having an identical orientation, the orientation of the members along one edge being different from that of the members along the opposite edge, one side of each of said members being secured to the same side of said plate, whereby when air is directed through the members which are arranged along one edge of the plate the heat transfer efficiency of the heat sink is substantially increased as a result of inhibiting the formation of a thermal boundary layer along the members which are arranged along the opposite edge of the plate.

4. The heat sink according to claim 3, wherein said plate is comprised of Kovar, and said members are comprised of copper.