JP2002141688A - Device for dissipating heat from circuit element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat sink device which dissipates heat to the most without being coupled to an IC nor fitted to a PCB or the lower edge of an IC package. SOLUTION: A device is provided in which a heat is dissipated from at least one circuit element fitted to a printed circuit board. The device is provided with a heat sink comprising at least a pair of arms containing a slot, respectively, and has a structure where it is coupled to the printed circuit board by at least two side surfaces. The structure comprises an upper edge which comprises a tab so provided as to allow the slots of the arms to be held.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to the cooling of circuit elements,
More particularly, it relates to an apparatus for dissipating heat from circuit elements mounted on a printed circuit board.

[0002]

2. Description of the Related Art Generally, a heat sink is an integrated circuit (I).
Dissipate heat from C) to the surrounding air. Currently, there are two main approaches to installing such a heat sink. In the first approach, the heat sink is I
Combined on top of C. In coupling, the coupling line between the IC and the heat sink must be thin enough to ensure minimal thermal resistance in the coupling material. Unfortunately, if the IC emits too much heat, delamination of the heat sink can occur. Free heat sink
Contact with other circuits can cause an electrical short, where improperly coupled heat sinks do not dissipate heat from the IC.
Thus, bonding is an inadequate solution when maximum heat dissipation is required.

[0003] In a second approach, a heat sink is mechanically attached to a heat sink and a printed circuit board (PCB) such that the IC is sandwiched between the heat sink and a printed circuit board (PCB). In particular, the heat sink may either secure the heat sink to the IC via a clip attached to the underside of the IC package (ie, piggyback attachment), or attach the heat sink to the PCB using a spring clip or screw. Mounted by way.
Piggyback mounting has a low profile package such as a quad flatpack (QCP) or ball grid array (BGA) package because there is only a minimal gap for mounting a heat sink between the IC and the PCB. ICs are not typically used. Mounting the heat sink to the PCB using spring clips or screws isolates the mounting area from the PCB traces, thereby reducing the space available for circuit routing. Thus, knowledge of heat sink placement is required prior to design, often requiring the PCB to be expanded to accommodate the heat sink.

[0004]

Therefore, there is a need in the art for a heat sink arrangement that maximizes heat dissipation without being bonded to an IC or attached to a PCB or to the lower edge of an IC package.

[0005]

SUMMARY OF THE INVENTION The disadvantages associated with the prior art are overcome by an apparatus for dissipating heat from at least one circuit element mounted on a PCB. In the illustrated embodiment of the present invention, the 2
A heat sink radiating heat from the three ICs is coupled to the structure around the PCB. The surrounding structure is an RF shield.
The heat sink has two bases, one for each IC, for thermal contact, and further has two sets of arms to dissipate heat and couple the heat sink to the surrounding structure without contacting the PCB. If the IC has a conductive package, a non-conductive thermal spacer is inserted between each base and the corresponding IC to electrically insulate the heat sink from the IC. Further, each arm has wings extending vertically therefrom, substantially increasing its surface area for increased heat consumption and structural stability.

The heat sink is attached to the surrounding structure using a twist tab. Each arm includes a slot for receiving a twist tab extending from a surrounding structure. In another embodiment of the invention, both sides of the heat sink are snap-locked to the surrounding structure, or one side of the heat sink is hooked into a slot on the surrounding structure while the other side or end is threaded, twisted. It is mechanically held using tabs or snap locks. Because the heat sink does not contact the PCB, the PCB can be made smaller and tracing is minimized.

[0007] Further embodiments of the present invention will become apparent from the detailed description included hereinafter. However, it should be understood that the detailed description and specific examples are given by way of illustration only, as various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. .

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings.

[0009] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.

FIG. 1 shows an embodiment of a heat sink 10 according to the present invention. In particular, the heat sink 10 includes a main body 11,
It has a first set of arms 25 and a second set of arms 43. The main body 11 includes a first rectangular base 12, a second
, A rectangular base 30 and a rectangular connecting member 28. Those skilled in the art will recognize that the first base 12, the second base 3
It is understood that the connection member 28 may be formed using a non-rectangular shape. Further, while the heat sink 10 of FIG. 1 is primarily described in terms of rectangles and other specific shapes, it will be understood that various modifications to such shapes are contemplated by the inventors within the scope of the invention.

The first rectangular base 12 has a first left side wall 14, a first right side wall 16, and a first back wall 18, each of which is separated from the first rectangular base 12. Extends vertically. Extending from the first left side wall 14 is a first left arm 20, which is a first left wing 2.
The first left wing 22 extends vertically from the first left arm over substantially the majority of the length of the first left arm. From the first right side wall 16, the first right arm 2
4 and the first right arm 24 is connected to a first right wing 26
And the first right wing 22 extends vertically from the first right arm 24 over substantially the majority of the length of the first right arm 24. The first left arm 20 and the first right arm 24 combine to form a first set of arms 25, each arm having a slot at a location spaced from the first left side wall 14 and the first right side wall 16, respectively. 46.

The second rectangular base 30 has a second left side wall 32, a second right side wall 34, and a second back wall 36, each of which extends from the second rectangular base 30. Extends vertically. Extending from the second left side wall 32 is a second left arm 38, which is connected to the second left wing 4
0, and the second left wing 40 has a second left arm 38.
Over substantially the majority of the length of the second left arm 38
Extending in the vertical direction. Extending from the second right wall 34 is a second right arm 42, which has a second right wing 44, which is a second right arm. Extending vertically from the second right arm 42 over substantially the majority of its length. The second left arm 38 and the second right arm 42 together form a second set of arms 43, each of which has a slot at a location spaced apart from the second left side wall 32 and the second right side wall 34, respectively. 46
including.

The first back wall 18 is joined to the first left side wall 14 and the first right side wall 16. The second back wall 36 is joined to the second left side wall 32 and the second right side wall 34. A rectangular connection 28 connects the first back wall 18 to the second back wall 36.
(Fig. 2).

The heat sink 10 is made of a heat conductive material such as aluminum. Important bends of the heat sink 10 include gussets 49, which provide mechanical strength to avoid deformation and have sufficient bend radii to not restrict the conductive flow of heat through the metal. . The bases 12 and 30 are designed to mechanically mate with the desired circuit elements using an interference or compression fit;
Thereby, sufficient pressure is applied to ensure heat transfer from the circuit elements to the heat sink 10. That is,
The interference fit provides mechanical support and low thermal resistance by ensuring a large "contact patch" between the heat sink 10 and the circuit elements.

The bases 12 and 30 may be in direct contact with a circuit element having a non-conductive package (eg, a ceramic package) or, if the circuit element has a metal package, a conductive insulator. Can be thermally coupled to circuit elements using conductive spacers. Although the heat sink 10 of FIG. 1 is made of aluminum, those skilled in the art
It is understood that the heat sink 10 can be made of any thermally conductive material (eg, metal, metal composite, polymer).

FIG. 2 is an isometric view of the circuit elements 48 mounted on a printed circuit board (PCB) 58. Circuit element 48
Illustratively, an integrated circuit encapsulated in a package 50 having a substantially flat top surface 52 and a bottom surface 54 on the opposite side, such as a quad flat pack (QFP) or ball grid array (BGA) package. (I
C). The lead wire 56 is connected to the I
C and extend outwardly for attachment to PCB 58.

Although the present invention is described in terms of enhancing the cooling of a packaged IC, it is understood that the principles of the present invention can be used with all heating circuit elements. Such devices do not necessarily require a flat surface, as conductive compounds can be utilized to ensure good surface contact on uneven surfaces. Further, the IC 48 is connected to the PCB 58
While illustrating a conventional lead 56 for attachment to a device, those skilled in the art will appreciate that the present invention may be implemented with circuit elements having other types of connection elements, such as ball grid solder bumps.

FIG. 3 shows an assembly including a heat sink according to the present invention. In particular, FIG. 3 is an isometric view of an enclosure or module having a heat sink formed in accordance with the present invention that cooperates with the enclosure 60 to have a PC board containing an integrated circuit that cooperates thermally with the heat sink. The heat sink mechanically cooperates with the enclosure and the PCB such that a low thermal resistance path is formed between the heat sink and the integrated circuit on the PC board to be cooled.

The enclosure 60 has a longitudinal member that is oriented perpendicular to the edge of the PCB 58.
Other shapes (eg, circles, ovals, etc.) and orientations that include some or all of the PCT are also within the scope of the invention.

The upper edges 64 of two corresponding longitudinal members 62
Note that there are tabs 70 that are spaced apart.

FIG. 3 shows the containment structure 6 surrounding the PCB 58.
Combined with zero. The containment structure 60 has longitudinal members 62 on both sides of the PCB 58. Each longitudinal member 62 has a top edge 64 and a bottom edge 66, and the bottom edge 6 of each longitudinal member 62.
6 is attached to the PCB 58. On the upper edge 64 of the two corresponding longitudinal members 62 are tabs 70 that are equidistantly spaced from one another. The structure 60 is a PCB 58
, For example, an RF shield.

In this embodiment, the first set of arms 25 and the second set of arms 43 of the heat sink 10 are shown attached via structural tabs 70 and heat sink slots 46, respectively. Heat sink 10 and structure 60
Are shown with slots and tabs 2, respectively, but other attachment methods may be used, such as screws, twist tabs, snap locks, or combinations thereof. Further, while the heat sink 10 is shown as being detachable from the structure 60, it may be permanently fixed in place.

In another embodiment, each longitudinal member 62 has an inner surface 63. A support member 65 (FIG. 4) is attached to the inner surface 63 of each longitudinal member 62 and a PCB 58 is placed on each support member 65.

The first set of arms 25 and the second set of arms 43 also have electronic components 48 that are the first rectangular base 12
And / or provides a large surface area for dissipating heat from circuit element 48 when in thermal contact with second rectangular base 30. Although not shown, a thermally conductive spacer that is an electrical insulator can be used with the present invention. Spacers may be used, for example, when electronic component 48 has a metal enclosure that is not electrically isolated. Additionally, thermally conductive spacers may be used when there is an insufficient amount of interference between the heat sink and the electronic component.

Thus, as noted, the present invention enhances the cooling of at least one conventional electronic component by providing additional heat dissipation surfaces on the upper surface of the component. By utilizing the device coupled to the chassis structure, the present invention dissipates heat from the electronic components to the surrounding air. This can be achieved without changing the design of the component parts according to the needs.

While various embodiments incorporating the teachings of the present invention have been shown and described in detail herein, those skilled in the art can readily devise numerous other modified embodiments that still incorporate these teachings.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a heat sink according to the present invention.

FIG. 2 is an isometric view of a circuit element mounted on a printed circuit board.

FIG. 3 illustrates a heat sink of the present invention coupled to a structure surrounding a printed circuit board.

FIG. 4 is a view showing a structure surrounding a printed circuit board including a support member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Heat sink 11 Main body 12 1st rectangular base 14 1st left side wall 16 1st right side wall 18 1st back wall 20 1st left arm 22 1st left wing 24 1st right arm 26 1st Right wing 25 First set of arms 28 Rectangular connecting member 30 Second rectangular base 32 Second left wall 34 Second right wall 36 Second back wall 38 Second left arm 40 Second left wing 42 Second right arm 43 Second set of arms 44 Second right wing 46 Slot 48 Integrated circuit (IC) 49 Gusset 50 Package 52 Top surface 54 Bottom surface 56 Lead wire 58 Printed circuit board 60 Enclosure 62 Long shaft member 63 Surface 64 Top edge of longitudinal member 66 Bottom edge of longitudinal member 70 Tab

 ──────────────────────────────────────────────────続 き Continued on the front page (71) Applicant 300000708 46, Quai A, Le Gallo F-92648 Boulogne Cedex France (72) Inventor Donald Ray Shelton United States of America Indianapolis 46201 Indianapolis North Riley 4411 F-term (reference) 5E321 AA01 GG05 GH03 5E322 AA01 AB01 AB08 FA04 5F036 AA01 BA23 BB01

Claims (24)

[Claims] An apparatus (10) for dissipating heat from at least one circuit element mounted on a printed circuit board (PCB) (58) fixed to a chassis (60), comprising: a body; and the body. Heat sink (10) having at least two arms (25, 43) extending therefrom and cooperating mechanically and thermally with said at least one circuit element
And a mechanical coupling means (46, 70) for fixing the heat sink to the chassis. 2. The heat sink of claim 1, wherein said body has at least one base portion in thermal contact with a respective circuit element.
The device according to claim 1, comprising: (8). 3. The apparatus of claim 2, wherein a thermal spacer (62) couples with said at least one base and said respective circuit elements. 4. The mechanical coupling means includes a twist tab (70), a snap lock, a screw, and a slot (4).
6. The method according to claim 1, wherein the tab set is selected from the group consisting of:
The described device. 5. The at least two arms (25, 4).
3) The apparatus of claim 1, wherein each includes a wing (22, 26, 40, 44), wherein the wing extends vertically from the arm and over substantially the entire length of the arm. 6. The apparatus of claim 1, further comprising a structure coupled to said PCB (58) and said mechanical coupling means for securing said heat sink to said PCB. 7. The apparatus of claim 6, wherein the structure includes at least two sides and a support member mounted on each side for supporting the PCB (58). 8. The apparatus of claim 1, wherein said chassis has a radio frequency (RF) shield. 9. The apparatus of claim 1, wherein said circuit element comprises one of a quad flat pack (QFP) and a ball grid array (BGA) package. 10. The circuit element has a conductive package (50), and the circuit element is connected to the heat sink (10) via an electrical insulator disposed between the circuit element and the heat sink. The apparatus of claim 1, wherein the apparatus cooperates mechanically and thermally. 11. The apparatus of claim 10, wherein said electrical insulator has at least one thermally conductive spacer. 12. The apparatus of claim 5, wherein each said arm has a respective inner surface cooperating with a support member that provides mechanical support to said PCB. 13. An apparatus for use in an assembly having a printed circuit board (PCB) including at least one circuit element secured to a chassis, comprising: a body; and at least two arms extending from the body. An apparatus comprising: a heat sink mechanically and thermally cooperating with the at least one circuit element; and mechanical coupling means for securing the heat sink to the chassis. 14. The apparatus of claim 13, wherein said body of said heat sink has at least one base portion in thermal contact with a respective circuit element. 15. The apparatus of claim 14, wherein a thermal spacer is associated with said at least one base and said respective circuit elements. 16. The mechanical coupling means includes a twist tab (70), a snap lock, a screw, and a slot (4).
6. The method according to claim 1, wherein the tab set is selected from the group consisting of:
3. The device according to 3. 17. Each of said at least two arms,
14. The apparatus of claim 13, including a wing, wherein the wing extends vertically from the arm and over substantially the entire length of the arm. 18. The heat sink according to claim 1, wherein the heat sink is connected to the PCB (5).
14. The device according to claim 13, further comprising a structure coupled to said PCB (58) and said mechanical coupling means (46, 70) for fixing to said 8). 19. The structure according to claim 19, wherein the structure comprises at least two sides:
19. The apparatus of claim 18, further comprising a support member attached to each of said sides to support said PCB. 20. The system as claimed in claim 19, wherein the chassis is a radio frequency (RF).
14. The device according to claim 13, comprising a shield. 21. The apparatus of claim 13, wherein said circuit element comprises one of a quad flat pack (QFP) and a ball grid array (BGA) package. 22. The circuit element has a conductive package, and the circuit element is mechanically and thermally connected to the heat sink via an electrical insulator disposed between the circuit element and the heat sink. 14. The device of claim 13, which cooperates. 23. The apparatus of claim 22, wherein said electrical insulator has at least one thermally conductive spacer. 24. The apparatus of claim 17, wherein each of the arms has a respective inner surface that cooperates with a support member that provides mechanical support to the PCB.