Thermal junction for card edges in a card cage and ground clip therefor

• US 5,343,361 A
• Filed: 06/11/1993
• Issued: 08/30/1994
• Est. Priority Date: 06/11/1993
• Status: Expired due to Term

• Current Assignee: The Whitaker Corporation (Meggitt PLC)
• Original Assignee: The Whitaker Corporation (Meggitt PLC)
• Inventors: Stahl, Daniel E., Rudy, William J. Jr., Shaffer, Howard R.
• Primary Examiner(s): Thompson, Gregory D.
• Application Number:
  US08/076,614
• Time in Patent Office: 445 Days
• Field of Search: 174/35 R, 174/35 C, 174/51, 361/644, 361/676, 361/678, 361/690, 361/704, 361/710-711, 361/725, 361/753, 361/796, 361/797, 361/799, 361/800, 361/816, 361/818, 361/831, 439/61, 439/64, 439/108, 439/485, 439/607, 439/609
• US Class Current: 361/710
• CPC Class Codes: H05K 7/1412 hold down mechanisms, e.g. avionic racks
• CPC Class Codes: H05K 7/1449 with connections to the back board
• CPC Class Codes: H05K 9/0016 having a spring contact

Abstract

A thermal junction (64) with an edge (106) of a daughter card (100) in a card cage enclosure (10). A front panel (50) of the enclosure includes an array of interior fins (58) extending to edges (60) adjacent the edges (106) of the array of daughter cards (100). Spring clips (62) mounted along the fin edges engage the card edges simultaneously upon the front panel (50) being placed in position, and spring arms (70) of each clip establish a plurality of assured thermal connections of the card edges with the fins, for the front panel (50) to dissipate heat from the circuit cards (100) to the exterior of the enclosure (10). With cards having a metal shielding layer (110), the spring clips (62) also define a ground to the enclosure wall.

Claims

1. A junction box for a plurality of electrical interconnections of circuits of circuit cards with electrical conductors extending into the junction box at an input/output interface, comprising:

a body member defining opposed side walls and opposed top and bottom walls extending from a front face to a rear wall, a front panel member securable to said front face to define a front wall traversing a card-receiving opening, and a backplane assembly proximate and affixed to said rear wall and including a transverse interior wall positioned rearwardly of a card-receiving region proximate said front panel, all generally defining a card cage;

said side walls and top wall and bottom wall and rear wall and front panel member being formed of thermally and electrically conductive material of substantial thickness and being substantially free of openings, said side walls and said top and bottom walls adjoined to edges of adjacent ones thereof and said rear wall being adjoined to rear edges of said opposed side walls and said top and bottom walls in a manner to eliminate any gap thereat through which electromagnetic and radiofrequency energy could otherwise pass;

said rear wall including an array of electrical input/output connectors mounted thereon adapted to be mated with complementary electrical connectors and defining an input/output interface, said rear wall including shield sections surrounding respective said input/output connectors in a manner eliminating any gap peripherally therearound through which electromagnetic and radiofrequency energy could otherwise pass,

said interior wall including an array of card connectors mounted thereon to mate with corresponding connectors of a plurality of circuit cards insertable into said body member, and one of said opposing side walls or said top and bottom walls including pairs of card guide means extending from front edges thereof to said interior wall and cooperating to guide movement of respective said circuit cards during insertion and removal, with said card connectors aligned with respect to respective said pairs of card guide means to mate with complementary connectors along leading ends of respective said circuit cards during card insertion;

said backplane assembly defining an array of electrical circuits connecting terminals of said card connectors mounted on said interior wall to terminals of said input/output connectors mounted on said rear wall;

said front panel member being securable to said body member to tightly abut front edges of said opposed side walls and said top and bottom walls in a manner to eliminate any gap thereat through which electromagnetic and radiofrequency energy could otherwise pass, and securable in a manner facilitating removal thereof to permit insertion and removal of a said circuit card;

said front panel member including an array of fins extending into said card-receiving region to facilitate absorption of thermal energy therefrom, said fins being associated with respective circuit cards and extending to card-proximate ends adjacent to trailing edges of said cards and having secured therealong respective spring clips each defining an edge-receiving entrance therealong aligned with a said pair of card guide means to become at least thermally connected to substantial length of a said trailing edge of a respective said circuit card inserted along said pair of card guide means, upon securing said front panel member to said front face of said body member,

whereby a compact card cage of robust construction is defined adapted to shield said circuit cards and electrical interconnections thereof with said electrical conductors from electromagnetic and radiofrequency interference and to facilitate dissipation of thermal energy therefrom.

2. A junction box as set forth in claim 1 wherein at least one said spring clip is electrically conductive, whereby upon engagement with a shielding layer of an associated said circuit card, a ground path is defined to said front panel grounding said shielding layer.

3. A junction box as set forth in claim 1 wherein each said spring clip includes a mounting section joined to a card-remote portion of a respective said fin, a body section extending from said mounting section and along a surface of said fin parallel and adjacent to a trailing edge portion of a respective said circuit card, and a spring arm section joined to said body section at a bight section forwardly of said trailing edge of said circuit card and extending to a constriction at a card-proximate end of said fin and concluding in a diverging free end to define said edge-receiving entrance, whereby said trailing edge portion of said circuit card is received into said edge-receiving entrance and deflects outwardly said spring arm section under spring bias which establishes an assured engagement of said trailing edge portion with said body section for thermal transmission to said body section and said fin.

4. A junction box as set forth in claim 3 wherein each said spring arm section is defined by an array of discrete spring arms.

5. A front panel for a card cage for traversing a front face thereof to enclose a card-receiving region, comprising:

a member formed of thermally and electrically conductive material of substantial thickness and being securable to a body member of the card cage to tightly abut front edges of opposed side walls and top and bottom walls thereof in a manner to eliminate any gap thereat through which electromagnetic and radiofrequency energy could otherwise pass, and securable in a manner facilitating removal thereof to permit insertion and removal of a circuit card;

said member including an array of fins extending into the card-receiving region to facilitate absorption of thermal energy therefrom, said fins being associated with respective circuit cards and extending to card-proximate ends adjacent to trailing edges of said cards and having secured therealong respective spring clips each defining an edge-receiving entrance therealong to be at least thermally connected to a said trailing edge of a respective said circuit card upon securing said front panel member to said front face of said body member.

6. A front panel as set forth in claim 5 wherein at least one said spring clip is electrically conductive, whereby upon engagement with a shielding layer of an associated said circuit card, a ground path is defined to said front panel grounding said shielding layer.

7. A front panel as set forth in claim 5 wherein each said spring clip includes a mounting section joined to a card-remote portion of a respective said fin, a body section extending from said mounting section and along a surface of said fin parallel and adjacent to a trailing edge portion of a respective said circuit card, and a spring arm section joined to said body section at a bight section forwardly of said trailing edge of said circuit card and extending to a constriction at a card-proximate end of said fin and concluding in a diverging free end to define said card-receiving entrance, whereby said trailing edge portion of said circuit card is received into said edge-receiving entrance and deflects outwardly said spring arm section under spring bias which establishes an assured engagement of said trailing edge portion with said body section for thermal transmission to said body section and said fin.

8. A front panel as set forth in claim 7 wherein each said spring am section is defined by an array of discrete spring arms.

9. A thermal junction of an edge of a circuit card to card cage framework, comprising:

a panel member of the card cage framework securable to a front face thereof traversing a card-receiving opening of a card-receiving region thereof;

a circuit card insertable into said card-receiving region;

a fin section of said panel member associated with and parallel to a trailing edge of said circuit card to be adjacent thereto; and

a spring clip secured to one of said trailing edge and an edge of said fin section defining an edge-receiving entrance therealong to be at least thermally connected to the other of said trailing edge of a respective said circuit card and fin section edge upon securing said front panel member to said front face of said body member.

10. A thermal junction as set forth in claim 9 wherein said spring clip is electrically conductive, whereby upon engagement with a shielding layer of an associated said circuit card, a ground path is defined to said front panel grounding said shielding layer.

11. A thermal junction as set forth in claim 9 wherein said spring clip includes a mounting section joined to a card-remote portion of a respective said fin section, a body section extending from said mounting section and along a surface of said fin section parallel and adjacent to a trailing edge portion of a respective said circuit card, and a spring arm section joined to said body section at a bight section forwardly of said trailing edge of said circuit card and extending to a constriction at a card-proximate end of said fin section and concluding in a diverging free end to define said card-receiving entrance, whereby said trailing edge portion of said circuit card is received into said edge-receiving entrance and deflects outwardly said spring arm section under spring bias which establishes an assured engagement of said trailing edge portion with said body section for thermal transmission to said body section and said fin section.

12. A thermal junction as set forth in claim 11 wherein each said spring arm section is defined by an array of discrete spring arms joined by respective bight sections to an integral said body section.

13. A thermal junction as set forth in claim 11 wherein said mounting section extends around said card-proximate end of said fin and along a card-remote side thereof to a securing end section received into a recess behind a forwardly facing ledge held therein by strong spring bias of said mounting section compressing said securing end section toward said fin.

14. A thermal junction as set forth in claim 13 wherein said mounting section is defined by an array of discrete mounting spring arms joined by respective bight sections to an integral said body section.

15. A spring clip for engaging an edge of a circuit card in a card cage, comprising:

a mounting section for mounting to framework of the card cage proximate said edge of said circuit card;

a body section extending from said mounting section to an array of spaced bight sections; and

an array of spring arms coextending from respective said spaced bight sections along and converging toward said body section to respective constrictions and then diverging to respective free ends defining an edge-receiving entrance,

said mounting section extends to a securing end section extending toward said body section to be received into a recess behind a forwardly facing ledge of a fin of said framework and held therein by strong spring bias of said mounting section compressing said securing end section toward said fin when said mounting section is mounted to said card-proximate fin end and along a card-remote side of said fin.

16. The spring clip of claim 15 wherein said mounting section is defined by discrete spring arm portions extending from respective bight sections joining an integral said body section, and said securing end section is defined by inwardly bent free ends of said discrete spring arm portions each received into said recess.