MULTIPLE PLANAR HEAT SINK

Abstract: An electronic component heat sink comprising a base metallic plate (10) to which one or more electronic components (18, 20 and 22) are affixed. The base plate (10) is formed into a plurality of planar surfaces (12, 14 and 16) such that each electronic component (18, 20 and 22) remains flushly mounted to one of the planar surfaces (12, 14 and 16). The electronic components (12, 14 and 16) are usually flow soldered to the base plate (10) when the base plate (10) is in a single plane. The plate (10) is then bent to form the plurality of surfaces (12, 14 and 16). A second plate (24) can be flushly mounted against the base plate (10). The second plate (24) has planar surfaces (26, 28 and 30) correspnding to those of the formed base plate (10). The second plate (24) also usually has a plurality of fins (32, 34 and 36) extending from its side opposite from the side contacting the base plate (10).

Description: MU TIP E PLANAR HEAT SINK Background of the Invention The present invention relates to electronic component heat sinks and a method for manufacturing the same. More particularly, the invention relates to a heat sink having a plurality of planar surfaces with electronic devices mounted thereon. In soldering electronic components to heat sinks, it is desirable to use flow soldering techniques. Such flow soldering as presently known requires that the heat sink comprise a single planar surface. In the flow soldering operation, dots or discs of solder are placed at the areas of the plate at which a device is to be attached. The device, such as a button diode, is placed on the solder dots and the plate is passed through a furnace. The solder melts and all the desired devices are thusly soldered to the plate surface. Such limitation in the assembly of heat sinks with electronic components mounted thereon results in a corresponding limitation in the final desired configuration of the heat sinks, especially if flow soldering techniques were to be utilized in the assembly of the electronic components to the heat sink. If a multiple planar surface were passed through the furnace in the flow soldering operation, the planar surfaces not level would not support the devices to be connected or, if an indentation were placed in the surface.to hold such parts during soldering, the solder itself could flow out of the indentation. U.S. patent 4,321,664 discloses a heat sink utilized to hold diodes in a rectifier assembly. The heat sink is shown to comprise a sheet metal piece that is bent along two axes to form a U-shaped member. The diodes forming the rectifier circuit are placed or soldered in openings in the center base section of the heat sink. Such assembly of diodes is well known, with all diodes placed in a single plane of the heat sink. It is of special concern to provide an electronic component heat sink assembly wherein the assembly can be quickly and easily manufactured. Further, in view of the limited space available in the final use environment for the asseigbly, it is desirable that the assembly can be of as small a size as possible while providing acceptable heat absorption. The heat sink assembly should also be able to be formed in a variety of configurations to adapt the sink to its final environment while taking up a minimal amount of space in such environment. An example of such an application is an alternator in an automobile having an attached rectifier. Such rectifiers employ button, micro-button and chip diodes in order to reduce the overall size of the alternator. Such types of diodes must be soldered to a heat sink. The soldering is preferably done in a flow soldering technique, which must be performed along a single planar surface. Once such diodes are connected, the heat sink can be formed to the desired final shape. Accordingly, it is an object of the present invention to provide an improved electronic component heat sink assembly and a method of manufacturing the same. Summary of the Invention The present invention provides an electronic component heat sink assembly and a method of manufacturing the same. Such assembly comprises a metal plate structure capable of having electronic components flow soldered to it while the heat sink is in a single plane configuration. The heat sink should then be capable of being formed into a multi-planar arrangement wherein the electronic components affixed thereto maintain flush contact with one of the planes of the heat sink. It is a feature of the present invention that the electronic components need not be in a single planar face of the assembly, but rather can be distributed as deemed best about the various planar faces of the heat sink- ' . The method is further adaptable to provide for forming of the heat sink assembly after the initial bending of the heat sink to best accommodate the heat sink assembly in its final environment. The heat sink usually comprises a metal, usually of an aluminum base, plate formed into a plurality of planes. The electronic components remain flushly mounted to the planar surfaces. The metal plate could be of a steel composition to permit ready soldering thereto if steel would provide sufficient heat dissipation. If the base plate is of an aluminum base, it is usually necessary to coat the area to which the electronic components are to be flow soldered with a copper or brass deposit to permit the device to be flow soldered thereto. Such deposit could be done by a plasma arc depositing process. In particular, the present invention provides a method of manufacturing an electronic component-heat sink assembly including the steps of affixing one or more electronic components to a single planar metal plate and forming said plate into a plurality of planes such that one or more electronic component remains flushly mounted to at least two of said planes. The present invention also provides an electronic component heat sink comprising a metallic base plate having a plurality of generally planar surfaces, with one or more electronic components mounted to at least two of said planar surfaces. The first heat sink with mounted electronic components may be combined with a second heat sink having radiating fins for additional cooling capacity. Preferably this assembly would be done after the heat sink assembly with mounted electronic components was formed into its final configuration. The second heat sink itself would be manufactured usually in an extrusion process in- a similar configuration with planar surfaces corresponding to those of the first heat sink. The second heat sink would normally be of a metallic, usually above 99% by weight aluminum, composition and would comprise a base plate structure having a plurality of fins protruding from one side of the base plate. The other side of the base plate would remain flat to insure good contact against the first heat sink on the side opposite the side to which the electronic components are affixed. Such fins would usually be in groups to allow the base plate to be initially extruded or further bent into a configuration similar to the first base plate. The grouping of such fins allows a space to exist between each group of fins with an axis running between the groups of fins without the fins contacting each other. Such extrusion could usually be done prior to the press fitting of the second heat sink to the already formed first heat sink with mounted electronic components. Brief De cription of the Drawings In the drawings. Figure 1 is a side view of a first embodiment of the present invention; Figure 2 is a side view of the embodiment of Figure 1 with an additional joined heat sink; Figure 3 is a side view of a second embodiment of the present invention; Figure 4 is a side view of the embodiment of Figure 3 with an additional finned heat sink; Figure 5 is a side view of a third embodiment of the present invention; Figure 6 is a side view of the embodiment of Figure 5 with an additional finned heat sink; Figure 7 is a side view of a fourth embodiment of the present invention; Figure 8 is a side view of the embodiment of Figure 7 with additional finned heat sinks; and Figure 9 is a side view of a fifth embodiment of the present invention. Detailed Description of the Preferred Embodiment Referring now to Figures 1 and 2 of the drawings, a metal base plate is shown generally at 10 with button type diodes 18, 20 and 22 soldered thereto while base plate 10 is in a single planar configuration. After the soldering of diodes 18, 20 and 22, base plate 10 is formed or bent to comprise a multiple planar arrangement having planar surfaces 12, 14 and 16. In Figure 2, the same base metal plate 10 with mounted electronic components of Figure 1 is shown. However, base plate 10 has been press fitted and joined with an additional finned heat sink 24. Finned heat sink 24 comprises three planar surfaces 26, 28 and 30 which flushly contact, respectively, corresponding planar surfaces 12, 14 and 16 -5- of base " plate 10. Further, extending from the opposite side of finned heat sink 24 are groups of protruding fins 32, 34 and 36. Such groups are separated by spaces 38 and 40 to permit the extrusion of heat sink 24 without the fins themselves contacting each other. It is preferred to form base plate 10 and heat sink 24 separately and then press fit the two together. Referring now to Figures 3 and 4, a second embodiment of the present invention is shown. A planar base metal plate 40 is shown having outer planar surfaces 42, 44 and 46. Electronic components shown as button diodes 48, 50 and 52 are mounted on the opposite sides of these planar surfaces. Preferrably such mounting is accomplished by a flow soldering operation while base metal plate 40 is in a single planar configuration. L_ After such mounting, base plate 40 is formed by bending into the three planar configuration shown. Metal base plate 40 shown in Figure 4 is identical to base plate 40 shown in Figure 3. However, in the embodiment of the invention shown in Figure 4, base plate 40 has been press fitted into finned heat sink assembly 52. Finned heat sink assembly 52 is usually of a metal composition, usually an aluminum extrusion. Heat sink 52 includes planar surfaces 55, 57 and 59 which are flush mounted against corresponding planar surfaces 42, 44 and 46 of base plate 40. Separate groups of fins 54, 56 and 58 extend from heat sink 52 from the sides opposite planar surfaces, respectively, 59, 57 and 55. ϋsually base plate 40 and heat sink 52 are manufactured prior to their combination. Referring now to Figure 5, a third embodiment of the present invention is shown. Generally U-shaped base metal plate 62 and 64 are joined at their central planar portions 68 and 80 by a connection member 60. Base plate 62 is comprised of three planar sections 66, 68 and 70. Three electronic components shown as button diodes 72, 74 and 76 are affixed to the interior surface opposite outer faces 66, 68 and 70 of base plate 62. Generally U-shaped base plate 64 is comprised of three planar surfaces 78, 80 and 82. Electronic components shown as button diodes 84, 86 and 88 are affixed to the interior surfaces opposite base plate surfaces 78, 80 and 82. Both base plate 62 and 64 initially comprised a single planar surface to which the electronic components are flow soldered. After such flow soldering, base plate 62 and 64 are bent to form their U-shaped configuration. After such forming, center section 60 is affixed, usually by soldering, to center sections 6a and 80 of, respectively, base plate 62 and 64. Referring now to Figure 6, base plate 62 and 64 with the electronic components described above, are press ; fitted within finned heat sinks 92 and 103. Heat sink 92 comprises a generally U-shaped configuration having a plurality of fins 94 and 96 extending from the -leg portions. Interior surfaces 98, 100 and 1Q2 form a cavity to receive base plate 62. Guter surfaces 66, 68 and 70 of base plate 62 are in flush contact with the inner surfaces 98, 100 and 102 of the cavity of heat sink 92. Heat sink 103 is of a general U-shape having interior surfaces 108, 110 and 112 forming a cavity therein. A group of fins 104 protrudes from the leg portion of heat sink 103 opposite interior side 108, and a group of fins 106 protrudes from the leg portion of heat sink 103 opposite interior surface 112. Interior surfaces 103, 110 and 112 of heat sink 103 are in flush contact with exterior faces 78, 80 and 82 of base plate 64. Center structural component 61 is affixed to the exterior base wall 114 of heat sin* 103 and exterior base surface 116 of heat sink 92 thereby joining base plate heat sink combination 62, 92 and base plate heat sink combination 64 and 103. Referring now to Figure 7, a fourth embodiment of the present invention is shown generally at 119 as a combination of generally U-shaped base plate sections 120 and 142 joined by a central section 134. Base plate section 120 is comprised of outer surfaces 122, 124 and 126. Electronic components shown as button diodes 128, 130 and 132 are soldered to the opposite sides of base plate surfaces, respectively, 122, 124 and 126. Usually the electronic components are flow soldered on to base plate 120 when the base plate is in a single planar configuration, with base plate 120 then being bent to form the three planar surfaces 122, 124 and 126. The edges of surfaces 122 and 126 are affixed to sides of center section 134, usually by a soldering operation. Center section 134 is shown as further comprising electronic components 136, 138 and 140. The heat dissipation of base plates 120 and 142 is useful to transfer the heat from the electronic components mounted to center section 134. Generally U-shaped base plate section 142 is comprised of three planar surfaces 144, 146 and 148. Electronic components shown as button diodes 150, 152 and 154 are affixed to the interior surfaces of base plate section 142 opposite, espectively, surfaces 144, 146 and 148. Usually such components are flow soldered onto such surfaces when base plate section 142 is in a single planar arrangement, with base plate section 142 being bent to form planar sections 144, 146 and 148 after the affixing of the electronic components on the interior surface thereof. The end edges of surfaces 144 and 148 are affixed, usually by soldering, to a side of center section 134. Referring now to Figure 8, a combined heat sink and base plate assembly is shown generally at 155. Such assembly includes ' ase plates 120 and 142 joined by center section 134 as described above with reference to Figure 7. A generally U-shaped heat sink 156 comprises leg sections 158 and 162 joined by center section 160. Such sections form a cavity which is fitted around base plate section 120 such that base plate section 120 outer surfaces 122, 124 and 126 are in flush contact with the interior surface of leg sections 158 and 162 and center section 160 of heat sink 156. Multiple fins 159,161 and 163 protrude from the exterior surfaces of, respectively, leg section 158, center section 160 and leg section 162 of heat sink 156. Such heat sink 156 provides additional heat disipation for base plate 120 and the electronic components affixed thereto. Generally U-shaped heat sink 164 comprising leg sections 166 and 170 joined by center section 168 is also provided. These sections form a center cavity which is press fitfted such that the exterior surfaces 144, 146 and 148 of base plate section 142 are in flush contact with the interior surfaces of sections 166, 168 and 170. A plurality of fins 167, 169 and 171 protrude from the exterior surfaces of leg section 166, center section 168 and leg section 170 of heat sink 164. The fitting of heat sink 164 about base plate 142 provides additional heat dissipation for the electronic components connected to base plate 142. Referring now to Figure 9, a fifth embodiment of the present invention is shown. A base plate 180 is of a general channel shape having legs 184 and 186 joined by a center section which includes a recessed portion 182. Electronic components shown as button diodes 188, 190 and 192 are connected, respectively, to the interior surface of recessed section 182, leg section 184 and leg section 186. Such electronic components are normally connected to base plate 180 when the base plate comprises a single planar configuration as such connection is done by a flow soldering technique. Base plate 180 is then bent at about 90 degree angles to form end leg sections 184 and 186, and is further formed with two 90 degree bends near its center to form recess section 182. Shown within the cavity formed by legs 184 and 186 of base late 180 is base plate 200. Base plate 200 is of a- general U-shaped comprising leg sections 204 and 206. oined by a center section including recess portion 202. Electronic components shown as button diodes 208, 210 and 212 are affixed to the interior surfaces of, respectively, recessed center section 202, leg section 204 and leg section 206. The arrangement has shown in Figure 9 is to minimize the space taken by the six diode assembly, which is frequently connected to a single device such as an alternator to provide a rectifier circuit.

Claims: Claims What is claimed is: 1. A method of manufacturing an electronic component - heat sink assembly including the steps of: affixing one or more electronic components to a single planar metal plate and forming said plate into a plurality of planes such that one or more electronic component remains flushly mounted to at least two of said planes. 2. - The method of claim 1 wherein said electronic components comprise diodes. 3. The method of claim 1 wherein said plate is formed into three planes, each of which has an electronic device mounted thereto. 4. The method of claim 1 wherein said metal plate after being formed into a plurality of planes is joined to one side of a second plate having corresponding planes and a plurality of fins extending from the side of the second plate opposite from the side joined to said metal plate. 5. -The method of claim 1 wherein said metal plate is formed by a cold forming operation. 6. The method of claim 1 wherein said electronic components are soldered to said metal plate. 7. - An electronic component heat sink comprising: a metallic base plate having a plurality of generally planar surfaces, with one or more electronic components mounted on at least two of said planar surfaces. 8. The heat sink of claim 7 wherein a second plate having a number of planes corresponding to the number of base plate planar surfaces is joined to said base plate along one side of said second plate, said second plate having a plurality of fins extending from the side of said second plate opposite to the side contacting said base plate. 9. - An electronic component heat sink comprising; a base plate having at least two planar sections, the interior surface of each section adapted to receive at least one electronic component, a heat sink plate having at least two planar sections, the interior surface of each said heat sink planar section being in flush contact with one of the exterior surfaces of said base plate planar sections, and a plurality of fins extending from each of the exterior surfaces of said heat sink planar sections.

Inventors: KOWIESKI RAYMOND J, OCKEN ALFRED G, KOWIESKI, RAYMOND, J., OCKEN, ALFRED, G.
Applicants: MOTOROLA INC, MOTOROLA, INC.
Application year: 1985
Main classification: H05K7
IPC codes: H05K7