Heat sinks with staked solderable studs

• US 4,544,942 A
• Filed: 11/14/1984
• Issued: 10/01/1985
• Est. Priority Date: 02/22/1982
• Status: Expired due to Term

• Current Assignee: Aavid Thermal Products Incorporated (Ansys Incorporated)
• Original Assignee: Aavid Thermal Products Incorporated (Ansys Incorporated)
• Inventors: McCarthy, Alfred F.
• Primary Examiner(s): Larkins, William D.
• Assistant Examiner(s): Clark, Sheila V.
• Application Number:
  US06/671,033
• Time in Patent Office: 321 Days
• Field of Search: 357/81, 29/522, 29/509, 174/16 HS, 165/80 B, 165/80 D, 165/80 R
• US Class Current: 257/721
• CPC Class Codes: H01L 23/4093 Snap-on arrangements, e.g. clips
• 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: H05K 3/34 by soldering

Abstract

Heat sinks of the type which are fitted onto electronic solid-state devices to maintain acceptable thermal equilibrium conditions are provided with solderable sheet-metal appendages or studs staked onto their relatively cooler portions by way of punching which deforms and flows the heat-sink material into and through shaped openings so as to create sound mechanical interlocking. The studs are oriented for projection through a printed-circuit board, along with leads from the associated electronic device, for wave-soldering into rigidly-secured relation to the board.

Claims

1. Heat sink apparatus fastenable with a packaged electronic device for wave-soldered mounting on a printed-circuit board, comprising a metal heat sink having cooling portions remote from a portion adapted to be mated with a packaged electronic device, and relatively thin sheet-metal mounting studs each having a substantially flat and relatively broad-area portion abutted and staked with surfaces of said cooling portions which face inwardly of the exterior of said cooling portions and each having an elongated integral solderable tab portion depending therefrom in position to project through accomodating openings in a printed-circuit board and to bond with solder which locks the tab portion with the board and thereby holds the heat sink in place atop the board, said mounting studs each having a doubly non-symmetrical aperture therethrough into which material of an abutted cooling portion of said heat sink has been cold flowed by punching, said aperture being oriented substantially centrally of said broad-area portion and having a polygonal outline imparting an angular non-symmetry to it about its center and being non-symmetrical in the transverse direction by being flared outwardly in said transverse direction away from the side of said broad-area portion which abuts said heat sink, and said tab portion of each of said studs being laterally displaced slightly from said broad-area portion to form a bend at the lower edges thereof disposed for underlying contact with lower edges of said cooling portions of said heat sink and otherwise projecting downwardly substantially parallel with said broad-area portion, said bend augmenting angular locking effects and serving as a spacer between said lower edges of said cooling portions and the top of the printed-circuit board.

2. Heat sink apparatus as set forth in claim 1 wherein the material of said cooling portions of said heat sink is thicker and softer than that of said mounting studs and is not readily wettable by solder, wherein surfaces of the tab portions of said studs are readily wettable by molten solder and tend to retain masses of solder thereon, wherein material of said heat sink which has been cold-flowed through the apertures is peened over surfaces of said sheet-metal studs as the result of punching against exterior surfaces of said cooling portions which are aligned with said apertures in underlying sheet-metal studs which are in turn rigidly backed by a fixture member having a shallow recess allowing the softer material of said heat sink to cold-flow through said apertures and spread laterally beyond edges of said apertures to form rivet-like enlarged heads, wherein said sheet-metal studs and said apertures are of substantially rectangular outline, and wherein said apertures are flared outwardly along all edges of said rectangular outline thereof in direction away from the sides of the studs which abut with said cooled portions of said heat sink.