HK1029887A - Attachment of electronic device packages of heat sinks - Google Patents

Description

Securing electronic device packages to a heat sink

This is a continuation-in-part of the invention patent application entitled "mounting electronic device packages on a heat sink" filed serial No. 08/946,160 on 10/7/1997.

The invention relates to an assembly of a package and a heat sink of an electronic device. More particularly, the present invention relates to securing an electronic device package to two opposing sides of a heat sink body and to mounting the assembly to a circuit board or the like.

Many electronic component packages are designed to conduct heat generated by the circuit device chips contained therein to the surface of the package. Typically, one surface of the package is composed of plastic, ceramic, or metal that acts as a heat transfer medium to conduct heat generated by the electronic device to the exterior surface of the package. An external heat sink, such as a heat sink, must be configured to be in heat exchange relationship with the heat transfer medium to absorb heat and/or dissipate it to the surrounding environment. The heat sink may be a metallic piece of relatively high thermal conductivity, suitably shaped so that it can dissipate energy by convection, conduction or radiation. The heat spreader is typically an aluminum or aluminum alloy housing having a large surface area in the form of fins, or the like to facilitate heat dissipation therefrom.

The device package may be secured to the heat sink with an adhesive and/or mechanical means, such as screws and the like. Spring clip tongues may also be applied for easy fixing and dismounting of the device package. However, most spring clips are integral parts of the heat sink, and therefore require that each heat sink be specially shaped to receive each particular device package.

In mounting device packages on circuit boards and the like, it must be ensured that those packages requiring a heat sink mate with an appropriate heat sink and that the heat sink is positioned on the circuit board to allow for proper dissipation of heat. In many cases, the heat sink itself is fixed to the circuit board to ensure stability of the assembly, and in some cases to facilitate heat conduction from the device package. Circuit board assemblers must therefore design, manufacture and stock a vast number of heat sinks of various sizes, styles and shapes, each of which can accommodate only one or a few device packages.

The present invention provides a method and apparatus for assembling device packages on a heat sink and assembling the assembled assembly on a circuit board or the like, using a heat sink plate having fixing fingers or tongues on opposite sides thereof. The assembly allows component packages to be secured to either or both sides of the heat spreader plate, thereby increasing the packing density of the device packages on the circuit board. The heat sink plate of the assembly is rigidly fixed relative to the clip tongue. And therefore need not occupy both sides of the radiator panel of the assembly. The heat sink assembly may thus be used to support the device package on one or both sides. The fixation of the device package on one side is completely independent of the fixation of the device package on the other side.

In the preferred embodiment, the heat sink includes a mounting base adapted to be fixed to a circuit board or the like, and a heat sink plate adapted to be mounted on the mounting base. The configuration, size, etc. of the heat spreader plate and mounting base may be varied according to the number of electronic device packages requiring heat dissipation and their heat dissipation requirements. Because the mounting base and the rejector plate are separately formed, one or a few mounting bases may be designed to receive a wide variety of rejector plates. Thus, an appropriate heat sink plate may be selected for heat dissipation requirements and then directly inserted into a common or universal mounting base. Because the clip fingers or tongues operate independently on opposite sides of the heat sink plate, a variety of different sizes, shapes and numbers of packages can be mounted on one or both sides of the plate. Because the heat spreader plate is a single component that is mounted to a standard or universal mounting base, a wide variety of heat spreader plates and device packages can be mounted to the circuit board with a minimum number or even one universal standard mounting base.

Other features and advantages will be readily apparent from the following detailed description when taken in conjunction with the appended claims and the accompanying drawings, in which:

FIG. 1 is a perspective view of one embodiment of a heat sink plate of a heat sink assembly used in a presently preferred embodiment of the invention;

FIG. 2 is a perspective view of one embodiment of a mounting base of the heat sink panel shown in FIG. 1;

FIG. 3 is a front perspective view of the assembly of FIGS. 1 and 2;

FIG. 4 is a rear perspective view of the assembly shown in FIG. 3;

FIG. 5 is an exploded front perspective view of an assembly of the heat sink assembly and device package of the present invention;

fig. 6 is a rear perspective view of the assembly shown in fig. 5.

FIG. 7 is a perspective view of an alternative embodiment of a mounting base such as the radiator panel shown in FIG. 1;

figure 8 is a top view of a planar slit blank for forming the mounting base of figure 7,

fig. 9 is a top view of the mounting base of fig. 7.

Like reference numerals are used to refer to like elements throughout. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the inventive concepts disclosed herein, and are to be construed as illustrating the presently preferred embodiments of the invention. These drawings should not be construed as limiting the present invention to the illustrated and/or described embodiments.

The embodiment shown in FIGS. 1-6 includes a mounting base 20 (see FIGS. 1-4) that supports the rejector plate 10. The rejector plate 10 has opposed major surfaces 11, 11a and includes a plurality of fins 12 and the like. The radiator panel 10 is stamped or otherwise formed from a sheet blank to provide a large heat dissipation surface area. The size and shape of the heat sink 10 are determined by the heat dissipation requirements and size of the electronic device package mounted on the heat sink. It will be apparent that the size, shape, configuration, etc. of the rejector plate 10 may be varied as needed or desired.

The mounting base 20 includes a base portion 21 that supports an upwardly projecting tongue 22 and a tab 24. In the preferred embodiment, the mounting base 20 is also formed from a blank of sheet metal, but may be made from other materials. The fins 24 each include a notch 25 into which the heat spreader plate 10 shown in fig. 3 may be fitted. The mounting base 20 preferably includes a base portion 21 extending along a first plane with a tab 24 extending from and in a direction generally perpendicular to the first plane, as shown in fig. 2.

In the illustrated embodiment, the radiator panel 10 is inserted into the notch 25 on the fin 24 such that the main surfaces 11, 11a are perpendicular to the plane of the base portion 21 of the mounting base 20. If desired, one or more of the tabs 24 may include detents 26 (see fig. 2 and 3) adapted to engage with the or cut-out edges of the heat sink 12 on the plate 10 to securely and rigidly lock the heat spreader plate 10 in the slot 25.

The mounting base 20 supports a pair of oppositely disposed upwardly projecting tongues 22 located on opposite sides of the fin 24 and thus on opposite sides of the radiator panel. The mounting base 20 further comprises holes 23 in the base portion 21 so that leads of a device package mounted against the surfaces 11, 11a can pass through the mounting base 20, as shown in fig. 5 and 6. The mounting base 20 also includes a plurality of feet 27 extending opposite the direction of the tabs 24. The feet 27 are adapted to be inserted into appropriate holes in a circuit board or the like to secure the assembly to the circuit board.

As shown in fig. 5 and 6, the device package 30 may be inserted between the surface 11 and the tongue 22 and secured therebetween with a heat transfer plate 31 in direct thermal communication with the surface 11 of the rejector plate 10. Another device package may be mounted on the opposite side in a similar manner, as shown in fig. 6.

It should be noted that each tongue 22 operates independently of the other tongues. Because the radiator panel 10 is rigid and rigidly fixed to the mounting base 20, the tongues 22 operate completely independently of one another. Thus, a device package (e.g., package 30) may be mounted on one or both sides of heat spreader plate 10.

In the embodiment shown in fig. 7, 8 and 9, the mounting bracket 20 is cut from a flat sheet of metal (aluminum, aluminum alloy, etc.) in a symmetrical pattern as shown in fig. 8. The pattern includes a base 21, the base 21 having a large central aperture 23; there are two tongues 22, on diametrically opposite sides thereof; there are two fins 24 on diametrically opposite sides thereof. The feet 27 extend inwardly into the apertures 23. As shown in fig. 7 and 9, the fins 24 are folded parallel to each other (perpendicular to the base portion 21) so that a radiator panel 10 can be supported therebetween. It should be noted that when the flap 24 is folded upwardly, the feet 27 (which constitute an extension of the flap 24) extend in alignment in the opposite direction from the base portion.

The opposing tongues 22 are folded and curled slightly towards each other as a means of urging the electronic package into direct contact with the opposite side of the heat spreader plate 10 supported by the carrier support.

In the embodiment of fig. 7, 8 and 9, a slot 25 is formed in each tab 24. These slots 25 extend parallel to each other in alignment and perpendicular to the base portion 21. Each slot 25 includes a secondary slot 40 (two secondary slots per slot are shown in fig. 7-9). Each auxiliary slot extends generally parallel to the open end of the slot 25 and connects with the slot 25 at a point spaced from the open end to define a finger 41 extending inwardly towards the centre line of the slot 25. The free ends of fingers 41 undergo deformation to extend toward the vertical plane of slot 25 (or the closed end of slot 25 may be wider than the open end thereof) so that the free ends of fingers 41 will firmly engage heat sink plate 10 inserted into slot 25. In the embodiment shown in fig. 7, 8 and 9, the fingers 41 are formed on opposite sides of the open end of the slot 25, with the free ends of the fingers 41 being spaced less than the thickness of the heat sink plate 10 to be inserted therebetween. Thus, insertion of plate 10 into slot 25 requires slight compression of fingers 41 so that fingers 41 firmly grip plate 10. Fingers 41 are preferably slightly angled with respect to the centerline of slot 25 so that the free ends of fingers 41 engage the sides of plate 10 and act as barbs to prevent (or resist) withdrawal of plate 10 from slot 25. This construction allows these components to be rigidly assembled securely without the use of bolts, welding, etc.

In the illustrated embodiment, each electronics package 30 is mounted vertically with its leads 32 extending parallel to surfaces 11, 11a and through holes 23 so that the entire package can be mounted on a circuit board or the like by hand or by automated means. The assembly of device package (or packages) and heat sink can thus be easily handled and placed on the circuit board as a single unit (either manually or automatically) with the leads 32 and feet 27 passing through the appropriate holes in the circuit board. The heat sink may be soldered to the circuit board using the same soldering operation as the leads of the electronic device. After the assembly is mounted on the circuit board, the device package 30 can be removed from the circuit board without removing the heat sink by simply ironing down the solder-attached leads and then vertically pulling the package 30. The device package can be replaced quite easily.

Since the radiator plate 10 is disposed perpendicularly to the base portion 21 and the base portion 21 has a large hole, the device package can be inserted from both below and above the base portion 21. This configuration allows for automated assembly of the heat spreader and the device package.

Although the invention has been described with particular reference to a radiator assembly consisting of two stamped components of sheet metal blank, the invention is not limited thereto and may be assembled from a plurality of molded pieces or machined parts, or may be molded, machined, stamped or otherwise fabricated as an integral unit, for example. Likewise, the resilient fingers or tongues 22 may be of any form or shape. Such as flexible fingers or permanent notches, flanges, protrusions, etc., that align and/or secure the device package to the heat sink. Although only one tongue 22 is shown on each side of the assembly, multiple tongues or multiple tongues may be applied on each side of the heat spreader plate to secure one or more device packages. In addition, the tongue 22 may form a part of the radiator panel 10 instead of a part of the mounting base 20.

While the invention has been shown and described with reference to components that may be mounted in holes in circuit boards and the like, the invention is not so limited. For example, the foot 27 may be adapted for flat mounting by forming a horizontally extending surface on the foot. Likewise, the electronic device package may also be adapted for surface mounting without departing from the principles of the present invention.

It will be readily appreciated that the materials used to manufacture the heat sink mounting assembly of the present invention may vary depending on the requirements of the application. The actual size and shape of the components may likewise be varied to accommodate a variety of device packages of various sizes, shapes and requirements. For example, although the rejector plate and its mounting base are separate components according to the above description, the rejector plate may be changed as needed to accommodate various energy dissipation requirements. Different sizes, shapes, etc. of radiator panels may be designed for use with one size or shape of mounting base.

From the foregoing, it will be seen that the principles of the present invention may be employed in a variety of configurations to achieve a variety of beneficial advantages and features. It is to be understood that even though numerous characteristics and advantages of the present invention have been set forth in conjunction with details of construction and function of the invention, this disclosure is illustrative only. Various changes and modifications in detail, particularly in matters of size, shape and arrangement of parts, may be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (20)

1. An apparatus for mounting an electronic device package on a circuit board or the like, comprising:

(a) a rigid heat spreader plate having oppositely disposed first and second major surfaces;

(b) a single unitary mounting base made of a highly thermally conductive material, comprising:

i) a base portion extending generally along a first plane and supporting the radiator panel

Said first and second major surfaces being substantially perpendicular to said first plane;

ii) at least one mounting foot formed by and extending from said base portion

The base part is fixed on a circuit board or the like;

c) a hole in the base portion and the first and second main surfaces of the heat sink

Alignment of the holes large enough to allow an electronic device package to be positioned along the first and second major surfaces

The direction of at least one of the surfaces passes through the hole;

d) at least one tongue disposed opposite each major surface and adapted to push against the electronic device package

And a member contacting one of the first and second major surfaces.

2. The apparatus of claim 1 wherein said mounting base includes wings extending from said base and extending in a direction generally perpendicular to said first plane.

3. The apparatus of claim 2 wherein said fins include notches and said heat sink plate is secured in said notches, said notches being aligned with said first and second major surfaces substantially perpendicular to said first plane.

4. The apparatus of claim 2, wherein said fins include detents that engage said heat sink plate to secure said heat sink plate to said mounting base.

5. The apparatus of claim 2, wherein the mounting base supports at least two tongues extending from the base in a direction generally perpendicular to the first plane.

6. The apparatus of claim 2, wherein the mounting base includes feet adapted for soldering to a circuit board or the like.

7. A device as in claim 3 wherein said tab includes at least one finger extending into one of said slots.

8. A device as claimed in claim 7, wherein the fingers are inclined to the centre line of the slot.

9. An apparatus for mounting an electronic device package, comprising:

(a) an integral mounting base made of a highly thermally conductive material having a first edge generally along a first side

A planar extending base portion having an aperture large enough to enable an electronic device

A package member passing therethrough;

(b) a pair of wings each having a longitudinal slot extending substantially perpendicularly from the base portion

Extending in the direction of the first plane;

(c) a high thermal conductivity radiator panel having first and second oppositely disposed major surfaces,

fits within the slot of the tab, substantially perpendicular to the first plane, and

the holes are aligned;

(d) at least one tongue, disposed opposite each of the major surfaces, is adapted to push an electronic device package into direct contact with the major surfaces.

10. The device of claim 9 wherein at least one of said tabs includes a finger extending into said slot therein.

11. The device of claim 9, wherein said fingers extend inwardly toward a centerline of said slot.

12. The apparatus of claim 9 wherein said mounting base has feet extending therefrom for securing said mounting base to a circuit board or the like.

13. The apparatus of claim 10 wherein at least one of said fins includes detent means for securing said heat sink to said mounting base.

14. An assembly, comprising:

(a) a heat sink, comprising:

(i) an integral mounting base made of a highly thermally conductive material having a first plane substantially aligned therewith

A face-extending base portion having an aperture large enough to enclose an electronic device

The fitting piece passes through the hole;

(ii) a high thermal conductivity radiator panel having first and second oppositely disposed major planar surfaces;

(iii) at least one tongue, arranged opposite each of said main surfaces, adapted to push a spring

An electronic device package in direct contact with the major surface.

(b) A fixing part fixed on one of the tongues and one main surface of the radiator plate

An electronic device package.

15. The assembly of claim 14 wherein said electronic device package has leads extending therefrom, said electronic device package being aligned such that said leads extend through said apertures.

16. A method of constructing a solderable mounted heat sink and electronic device package assembly comprising the steps of:

(a) forming an integral mounting base of weldable material having a mounting flange thereon

Holes large enough to pass an electronic device package therethrough and suitable for soldering

The connecting method is fixed on a circuit board or the like;

(b) forming a plurality of substantially thermally conductive fins adapted to be secured to said mounting base

A heater plate;

(c) aligning and securing the heat sink plate substantially perpendicular to the mounting base

One at a time, and aligned with the aperture;

(d) fixing at least one electronic device package on the heat sink plate

The lead wire passes through the hole;

(e) soldering the leads of the mounting base and the electronic device package to each other

A circuit board.

17. Apparatus for mounting an electronic device package on a circuit board or the like, comprising:

(a) a rigid heat spreader plate having oppositely disposed first and second major surfaces;

(b) an integral mounting base formed of sheet metal comprising:

(i) a base extending generally along a first plane and having a generally central aperture therein

A moiety;

(ii) a pair of rims on opposite sides of the aperture substantially perpendicular to the first plane

In directions extending substantially parallel to each other, each wing having a slot therein, the

The groove has an open end and a closed end and is adapted to be supported substantially perpendicular to said first end

A planar said radiator panel;

(iii) a pair of tongues extending substantially parallel to each other and to said tab,

adapted to push an electronic device package into engagement with the rigid heat sink plate

And (4) contacting.

18. The apparatus of claim 17 including legs extending from said mounting base for solderably securing said mounting base to a circuit board or the like.

19. The device of claim 17 including at least one finger extending from one of said tabs into a slot in said tab.

20. A device as claimed in claim 19, wherein said fingers project inwardly towards the centre line of said slot.