HEAT SPREADING PLATE HAVING ATLEAST ONE COOLING FIN METHOD FOR PRODUCING A HEAT SPREADING PLATE HAVING ATLEAST ONE COOLING FIN ELECTRONIC MODULE

Abstract

One aspect relates to a heat spreading plate having at least one cooling fin. The heat spreading plate includes at least a first layer and at least a second layer, and at least one surface portion bent out of a base surface of the second layer forms a cooling fin.

Claims

1-16. (canceled)

17. A heat spreading plate comprising: at least one cooling fin; at least a first layer; and at least a second layer; wherein at least one surface portion that is bent out from a base surface of the second layer forms a cooling fin.

18. The heat spreading plate of claim 17, wherein one of the first layer and the second layer is formed from a group comprising copper, a copper alloy, aluminium, an aluminium alloy, and aluminium silicon carbide (AlSiC).

19. The heat spreading plate of claim 17, wherein a connection layer comprising one of a group comprising a sintered layer, bonding layer, and solder layer is constituted between the first layer and the second layer.

20. The heat spreading plate of claim 17, wherein at least a third layer made of a low-expansion material comprising at least one of a group comprising a nickel alloy, invar (Fe.sub.65Ni.sub.35), invar 36 (Fe.sub.64Ni.sub.36), kovar (Fe.sub.54Ni.sub.29Co.sub.17), tungsten (W), an iron-nickel-cobalt alloy (FeNiCo alloy), molybdenum (Mo) is constituted between the first layer and the second layer.

21. The heat spreading plate of claim 17, wherein the at least one cooling fin is constituted one of pin-shaped, rectangular, semicircular, and square.

22. The heat spreading plate of claim 17, wherein the bent-out surface portion is arranged at an angle of 10-90 to the base surface of the second layer.

23. The heat spreading plate of claim 17, wherein a corrosion-inhibiting coating constituted at least in sections a galvanic nickel coating of the surface of the heat spreading plate.

24. A method for producing a heat spreading plate with at least a first layer and a second layer and at least one cooling fin, wherein at least one surface portion that is bent out from a base surface of the second layer forms a cooling fin, the method comprising: introducing at least one weakening contour or a recess into a base surface of the second layer, which weakening contour or recess borders a surface portion at least in sections in such a way that the surface portion is connected by at least one connecting point to the base surface, wherein the surface portion is then bent out of the base surface.

25. The method according to claim 24, wherein the weakening contour or the recess is introduced into the base surface of the second layer by means of cutting, in particular laser cutting or water jet cutting, and/or by means of milling and/or by means of stamping.

26. The method of claim 24, wherein the bending-out of the surface portion takes place by means of an upper stamp, in particular by means of an upper stamp and a counter-stamp formed complementary thereto.

27. The method of claim 24, wherein the second layer is connected to the first layer, in particular by soldering or diffusion annealing or sintering or eutectic bonding or low-temperature sintering or diffusion soldering or adhesive bonding.

28. The method of claim 24, wherein a third layer made of a low-expansion material, in particular of a nickel alloy, in particular invar (Fe.sub.65Ni.sub.35) or invar 36 (Fe.sub.64Ni.sub.36) or kovar (Fe.sub.54Ni.sub.29Co.sub.17), and/or tungsten (W) and/or an iron-nickel-cobalt alloy (FeNiCo alloy), particularly preferably molybdenum (Mo), is constituted between the first layer and the second layer.

29. The method of claim 28, wherein the first layer, the second layer and the third layer are connected together at a connecting temperature of 150 C.-300 C., in particular by a low-temperature sintering process.

30. An electronic module with at least one electronic component and with at least one heat spreading plate comprising at least one cooling fin, at least a first layer and at least a second layer, and wherein at least one surface portion that is bent out from a base surface of the second layer forms a cooling fin, wherein the at least one electronic component is connected indirectly or directly to a side of the first layer, which is constituted facing away from the second layer.

31. The electronic module of claim 30, wherein the second layer of the heat spreading plate is constituted as a component subjected to a cooling medium, comprising one of a group comprising air, water, glycol, and oil.

32. The electronic module of claim 31, wherein the at least one cooling fin is formed at an angle of 10-90, and one of perpendicular and parallel, to the flow direction of the cooling medium.

Description

[0065] The invention will be explained in greater detail below by reference to the appended schematic drawings on the basis of examples of embodiment. In these figures:

[0066] FIG. 1a shows the arrangement of individual layers and elements of a heat spreading plate with a cooling fin according to a first example of embodiment;

[0067] FIG. 1b shows a heat spreading plate with a cooling fin according to FIG. 1a in the connected state;

[0068] FIG. 2 shows a heat spreading plate with a plurality of cooling fins;

[0069] FIG. 3 shows a heat spreading plate with a plurality of cooling fins according to a further example of embodiment;

[0070] FIG. 4 shows an electronic module according to the invention with a concave formation of the heat spreading plate;

[0071] FIG. 5a-5e show individual process steps with regard to the bending-out of a surface portion; and

[0072] FIG. 6a-6c show individual process steps with regard to the connecting of the individual layers of the heat spreading plate.

[0073] Identical reference numbers are used below for identical and identically acting parts.

[0074] FIG. 1a represents the individual layers and surface portions of a heat spreading plate 10 to be produced (see FIG. 1b). Accordingly, first layer 20 and at least a second layer 30 are arranged one above the other. A connection layer 40 is constituted between first layer 20 and second layer 30. Second layer 30 comprises a base surface 31, which is essentially formed parallel to first layer 20. First layer 20 comprises a first side 21 and a second side 22. First side 21, which is constituted facing away from second layer 30, forms the surface of heat spreading plate 10 to be produced. Second side 22 of first layer 20 is facing towards second layer 30. Second layer 30 also comprises a first side 32, which is assigned to first layer 20. Second side 33 of second layer 30, on the other hand, is constituted facing away from first layer 20.

[0075] First layer 20 and second layer 30 are preferably produced from heat-conducting materials. These may be copper and/or a copper alloy and/or aluminium and/or an aluminium alloy and/or aluminium silicon carbide. Connection layer 40, which is constituted between first layer 20 and second layer 30, is preferably a sintered layer. This sintered layer can for example comprise silver particles.

[0076] A surface portion 50 is bent out from base surface 31 of second layer 30. This bent-out surface portion 50 forms the cooling fin. Bent-out surface portion 50 comprises a bending portion 51 and a surface-enlarging portion 52. Second layer 30 comprises a cutout 25 on account of bent-out surface portion 50. Access to second side 22 of first layer 20 can be created in the connected state of layers 20 and 30 (see FIG. 1b) on account of cutout 25. In the present case, connection layer 40 is not constituted in cutout 25. A sintering paste, which can form a connection layer 40, can be applied on first layer 20 or one second layer 30 for example with the aid of stencils, so that connection layer 40 can also comprise cutouts. Alternatively, it is possible for connection layer 40 to be constituted continuous, i.e. without cutouts.

[0077] In the present case, bent-out surface portion 50 is arranged at an angle of 90 to base surface 31 of second layer 30. Angle is formed between cooling surface 53 and second side 22 of first layer 20. In other words, angle is formed in the region of cutout 25.

[0078] The whole surface of heat spreading plate 10 preferably comprises a galvanically applied nickel coating. The nickel coating is corrosion-inhibiting. If heat spreading plate 10 is used as a water cooler, the galvanic nickel coating prevents the formation of corrosion. The surface of heat spreading plate 10 is understood to mean both first side 21 of the first layer 20 and also second side 33 of second layer 30. The surface of heat spreading plate 10 also includes cooling surfaces 53 and 54 of bent-out surface portion 50. The portion of second side 22 of first layer 20 lying in cutout 25 also belongs to the surface. This also applies to visible thicknesses d1 and d2 of first layer 20 and of second layer 30.

[0079] Alternatively, it is possible that only second layer 30 or second side 33 of second layer 30 and the cooling fin 50 comprises or comprise a nickel coating. In addition, the exposed portions of second side 22 of first layer 20 can comprise a coating. These portions of the heat spreading plate in particular are subjected to water or a liquid in the state when in use.

[0080] FIG. 2 represents a heat spreading plate 10 with a plurality of bent-out surface portions 50 which form cooling fins. A plurality of electronic components 70 are arranged on first side 21 of first layer 20. These electronic components 70 are located on a substrate plate 75. Substrate plate 75 is applied, together with electronic components 70, on first side 21 of first layer 20, for example by means of a solder joint 77. A bonding connection or a sintered connection could also be constituted instead of solder joint 77. Heat spreading plate 10 with cooling fins 50 and the electronic subassembly, which is formed by substrate plate 75 and electronic components 70, thus form an electronic module 80. Second layer 30 of heat spreading plate 10 is constituted as a component exposed to a cooling medium. The cooling medium can for example be air or a liquid.

[0081] The arrows constituted parallel to one another indicate flow direction S of the cooling medium. Cooling fins 50 are constituted perpendicular to flow direction S of the cooling medium. The incident flow of the cooling medium on cooling surfaces 54 of cooling fins 50 is therefore at right angles. On account of the incident flow on cooling surfaces 54 being at right angles, turbulence occurs between cooling fins 50, so that a particularly good cooling capacity is present here.

[0082] FIG. 3 represents a further embodiment of on an electronic module 80. Represented heat spreading plate 10 comprises a first layer 20, a second layer 30 and a third layer 45. This third layer 45 is a low-expansion layer. The low-expansion material can be a nickel alloy, in particular invar (Fe.sub.65Ni.sub.35) or invar 36 (Fe.sub.64Ni.sub.36) or kovar (Fe.sub.54Ni.sub.29Co.sub.17), and/or tungsten (W) and/or an iron-nickel-cobalt alloy (FeNiCo alloy). Molybdenum (Mo) or a molybdenum alloy has proved to be a particularly preferred material with regard to the low-expansion material of third layer 45. Third layer 45 can therefore be made of molybdenum or a molybdenum alloy or can comprise molybdenum or a molybdenum alloy. This low-expansion third layer 45 or this third layer 45 made of a low-expansion material produces a reduction in expansion with rising temperature and in this way reduces the expansion difference with respect to the materials of electronic components 70 and/or substrate plate 75. Stress-induced cracks are thus prevented from arising in the jointing zone between heat spreading plate 10 and substrate plate 75 and the heat flow is prevented from being significantly reduced on account of the cracks. This is typically the case with ceramic-based substrate plates, which have an average thermal expansion of 4-8 ppm/K. Third low-expansion layer 45 is made for example of molybdenum.

[0083] FIG. 4 represents a further heat spreading plate 10 with cooling fins 50. The layer structure of heat spreading plate 10 is asymmetrical. That means that thickness d1 of first layer 20 is greater than thickness d2 of second layer 30 and greater than thickness d3 of third layer 45. Third layer 45 is a low-expansion layer. On account of the asymmetrical formation, heat spreading plate 10 has a concave shape. The concave shape forms a depression 60 and an arched side 65.

[0084] FIGS. 5a-5e represent in steps how bent-out surface portion 50 of second layer 30 can be produced. FIG. 5a shows second layer 30 in a plan view onto first side 32. With regard to the orientation of first side 32 and second side 33, reference should be made to the previous explanations in connection with FIGS. 1a and 1b.

[0085] A plurality of recesses 90 are introduced into second layer 30. Overall, three horizontal rows and five vertical columns with a total of 15 recesses 90 are formed. Recesses 90 are constituted U-shaped. It is also conceivable for recesses 90 to the constituted V-shaped or semicircular. The spacings in the horizontal direction between recesses 90 lying in a line are identical. The spacings between recesses 90 next to one another in the horizontal direction are identical.

[0086] Recesses 90 are introduced into second layer 30, for example by cutting, in particular by laser cutting or water-jet cutting. It is also possible for recesses 90 to be introduced into second layer 30 by punching or milling. Recesses 90 border surface portions 92, wherein these surface portions 92 are the bent-out surface portions. In the not yet bent-out state, all surface portions 92 are in the same plane as base surface 31 of second layer 30. Each surface portion 92 is connected to base surface 31 at at least one connecting point 91. In other words, recess 90 should be introduced into base surface 31 in such a way that surface portion 92 cannot be completely severed from base surface 31. Connecting point 91 forms subsequent bending portion 51. The contour or the geometry of subsequently bent-out surface portion 50 is determined by the shape of recess 90.

[0087] After recesses 90 have been introduced into second layer 30, surface portions 92 are pressed out of base surface 31. For this purpose, second layer 30 is placed into a stamping device 100. Stamping device 100 comprises an upper stamp 101 and a counter-stamp 102. Upper stamp 101 comprises press-out studs 103. Upper stamp 101 preferably comprises as many press-out studs 103 as there are pressed-out surface portions 50 to be produced. Second layer 30 is positioned in stamping device 100 in such a way that press-out studs 103 can press on surface portions 92. Connecting points 91 preferably lie adjacent to the edges of walls 104 of counter-stamp 102. Counter-stamp 102 comprises recesses 105, into which press-out studs 103 can slide.

[0088] As is represented in FIG. 5e, surface portions 92 are pushed out or bent out of base surface 31 due to the pressures of upper stamp 101 and counter-stamp 102, said pressures prevailing in the arrow direction. Base surface 31 remains lying on anvil-like counter-element 106 (see FIG. 5c) of counter-stamp 102.

[0089] As represented in FIG. 5d, recesses 105 are wider than press-out studs 103, so that surface portions 92 can be pressed downwards vertically along wall 104.

[0090] As is represented in FIG. 5e, upper stamp 101 is pressed into counter-stamp 102 in such a way that surface portion 92 is bent at 90 to base surface 31. In this state, a completely bent-out surface portion 50 is present. The shape of walls 104 (see FIG. 5b) determines subsequent angle . Subsequent bending portions 51 are formed in each case at an edge of a wall 104.

[0091] FIGS. 6a to 6c represent, by way of example, how second layer 30 can be connected to the other layers of heat spreading plate 10 to be produced. For this purpose, upper stamp 101 with press-out studs 103 is moved away. Second layer 30 remains with bent-out surface portions 50 in the counter-stamp (see FIG. 6a). A connection layer 40 can next be applied on first side 32 of second layer 30. This connection layer 40 can for example be a bonding layer or a sintered layer or a solder layer. Connection layer 40 is preferably applied only one base surface 31 of first side 32. Third layer 45 made of a low-expansion material is preferably applied on connection layer 40. Third layer 45 can for example be a molybdenum layer. A connection layer 41 can in turn be applied on third layer 45. Here too, it can be a bonding layer or a sintered layer or a solder layer. First layer 20 is then arranged. Second side 22 of first layer 20 points in the direction of second layer 30.

[0092] The arrangement of individual layers 20, 30, 40, 41 and 45, as represented in FIG. 6b, is pressed with the aid of an upper stamp 110 and a counter-stamp 102. For example, this can take place as part of a low-pressure temperature sintering process. Here, a heat application at temperatures of 150 C.-300 C. takes place. A durable sintering connection is created by the application of pressures, which amount to between 5 MPa and 30 MPa, in particular 25 MPa, at a temperature of 250 C. for a duration of preferably 1 to 10 min, for example 4 min.

[0093] As represented in FIG. 6c, the removal of upper stamp 110 then takes place, so that heat spreading plate 10 can be removed from stamping device 100.

[0094] Finally, heat spreading plate 10 can be provided completely with a corrosion-inhibiting coating. For example, a nickel coating can be applied on the entire surface of heat spreading plate 10.