GB2079052A

GB2079052A - Cooling bodies for semiconductors or the like

Info

Publication number: GB2079052A
Application number: GB8120125A
Authority: GB
Original assignee: Alusuisse Holdings AG; Schweizerische Aluminium AG
Current assignee: Alcan Holdings Switzerland AG
Priority date: 1980-06-30
Filing date: 1981-06-30
Publication date: 1982-01-13
Also published as: DE3024748C2; GB2079052B; FR2485807A1; DE3024748A1; FR2485807B3; SE457584B; SE8103779L

Abstract

A sectional insert 10 may be placed between each two adjacent longer fins 3 to give additional cooling surfaces and divide the spaces into four ducts 14, 15. A heat sink for a semiconductor device is provided with fins 3, 4 of different heights arranged alternately. <IMAGE>

Description

SPECIFICATION Cooling bodies for semiconductors or the like The invention relates to cooling bodies for semiconductors or the like, with cooling ribs upstanding substantially at right angles from a base plate.

The cooling ribs are usually arranged on the base plate in the form of a comb, and are of equal length. For obtaining a greatest possible cooling effect, efforts are generally made to accommodate a very large surface in the smallest possible space.

This requirement leads, among other things, to manufacturing problems, because the wish to accommodate large surface in small space is contrary to the technical possibilities of manufacture by pressing.

Attempts to form the cooling ribs tapered in cross-section have indeed brought good results from a manufacturing viewpoint, which however were not satisfactory from a point of view of efficiency, because instead of the greatest output of heat, by reason of the narrowness of the cross-section of the gaps the air velocity as at its least.

In view of these circumstances, the inventor set himself the objective, to develop a cooling body of the kind mentioned initially, which produces an optimum cooling operation, and on the other hand can be made without problems and also economically.

What leads to the solution of this task is that the cooling ribs are provided of at least two different heights, and ribs of different heights are arranged alternately. Moreover, it has appeared to be advantageous, to introduce a sectional insert between two neighbouring cooling ribs, and to fix it there. If desired a plurality of sectional inserts, arranged in neighbouring gaps between cooling ribs, are united into a constructional unit.

Preferably a sectional insert is introduced between two long cooling ribs, and is fixed by clamping to the short cooling rib lying between the said long ribs. For this purpose the short cooling ribs, in the neighbourhood of their tips, preferably have elements promoting friction. For example they may be corrugated.

Preferably, on the tips, flat or corrugated, of the short cooling ribs, the sectional insert is pushed on, and for this purpose has a clamping jaw. The sectional insert may support itself against the opposing flanks of the long cooling ribs by strut arms spreading out from its sectional body. The said two longitudinal cooling ribs and one short cooling rib, with the sectional insert, form at least two, and preferably four, chambers.

For increase of the cooling effect, transverse ribs may extend from the sectional body of the sectional insert, transversely to the longithese ribs may be one half the length of the strut arms. Thus the transverse ribs extend into the chambers mentioned above, without engaging the flanks of the long cooling ribs.

It has proved to be advantageous to form the sectional insert with a clamping head, with an insert slot between two strut arms.

Thanks to the measures stated above, the flow conditions are significantly improved, by the special shape of the cooling body with substantially reduced rib proportion.

The cooling body according to the invention thus has ribs of different height, while the difference of height can be equalised by the clamped-on sectional inserts, which in turn have transverse ribs, and thus take part significantly in the cooling action. In this way, the rib proportion hitherto of 7.25 1 can be reduced to about 4 : 1. Furthermore, a significant improvement in manufacture is achieved; both the cooling body itself and also the sectional insert can be cut to length from extruded sections.

Further advantages, features and details of the invention appear from the following description of a preferred embodiment, with reference to the accompanying drawings, which show in: Figure 1: a cross-section through a part of a cooling body with sectional insert; Figure 2: a cross-section through a sectional insert.

A cooling body 1 has according to Fig. 1 a base plate 2 of thickness i of for example 1 5 mm, with cooling ribs 3, 4 extending from it of differing height a (for example 40 mm) and b (70 mm) respectively. The ribs have tapering cross sections and round rib tips 5, 6.

The base width d of the longer cooling ribs 3 3 amounts to 5 mm and is slightly greater than the base width e of the shorter cooling ribs 4. The width fat the tips 5 of the longer cooling ribs 3, 2.5 mm, is only slightly greater than the width g at the tips 6 of the shorter cooler ribs 4.

The rib height b of the longer cooling ribs 3 has a ratio to the clear spacing m between the ribs of about 3:1. The rib height a of the shorter cooling ribs 4 has a ratio to the spacing n indicated in Fig. 1 from a shorter rib to the adjacent longer rib of about 4:1. the base separation fbetween ribs measures about 7 mm.

The rib tips 6 can have corrugated surfaces, to give a better grip to a sectional insert 10, which can be pushed with a clamp-like head portion 11 onto the shorter cooling ribs 4 and then supports itself with strut arms 12, 13 against the flanks 9 of the longer cooling ribs 3. Thus four chambers 14, 15 arise within each valley between neighbouring longer colling ribs 3; inner chambers 14 are formed by the base plate 2, cooling ribs 3, 4, 3 and the strut arms 12 of the clamp-like formed by the tip zones of the longer cooling ribs 3, strut arms 1 3r and the body of the sectional insert 10.

From the step-like sectional body 20 of the sectional insert 10 there extend on both sides, transversely to its longitudinal axis M, transverse ribs 21 which can be of different height h and/or of the same height.

The two strut arms 12, 13 respectively of a strut arm pair are inclined each at the same angle t, w(Fig. 2) respectively, to the longitudinal axis M, while the strut arms 12 on the head portion 11 form a clamping slot 22. The strut arms 12, 13 on each side extend substantially parallel to one another.

The total length q of the cross section of the sectional insert 10 measures about 35 mm.

Claims

1. A cooling body for semiconductors or the like, with cooling ribs upstanding substantially at right angles from a base plate, characterised in that the cooling ribs are provided of at least two different heights, and the ribs of different heights are arranged alternately.

2. A cooling body for semiconductors or the like, with cooing ribs upstanding substantially at right angles from a base plate, characterised in that a sectional insert is introduced and fixed between two neighbouring cooling ribs.

3. A cooling body according to claim 1 and claim 2, characterised in that a sectional insert is introduced between two long cooling ribs, and is fixed by clamping to the short cooling rib lying between the said long cooling ribs.

4. A cooling body according to claim 3, characterised in that the short cooling ribs are formed in the neighbourhood of their tips in a manner encouraging friction.

5. A cooling body according to any of claims 3 to 4. characterised in that a plurality of sectional inserts are united into a constructional unit.

6. A cooling body according to any of claims 3 to 5, characterised in that the sectional insert is supported against the opposing flanks of the said long cooling ribs by strut arms spreading out from its sectional body, and/or is provided with at least one clamping jaw.

7. A cooling body according to claim 6, characterised in that transverse ribs extend from the sectional body of the sectional insert, transversely to the longitudinal axis of the latter, and the length of these ribs is about half the length of the strut arms.

8. A cooling body according to claim 7, characterised in that the lengths of the transverse ribs on one sectional insert face are different.

9. A cooling body according to any of claims 3 to 8, characterised in that the said two long cooling ribs and one short cooling rib, with the sectional insert, form at least two chambers.

10. A cooling body according to any of claims 3 to 9, characterised in that the sectional insert has a clamping head, with an insert slot between two strut arms.

11. A cooling body according to any of claims 1 to 10, characterised in that the height of the short cooling ribs measures about one third to one half of the height of the long cooling ribs.

12. A cooling body according to any of claims 1 to 11, characterised in that the height of the short cooling ribs has a ratio of about 4:1 to the clear width between it and the neighbouring long cooling ribs, and the height of the long cooling ribs has a ratio of about 3:1 to the clear width between these long cooling ribs.

13. A cooling body substantially as described with reference to Figs 1 and 2 of the accompanying drawings.