JP4862875B2 - Method for manufacturing thermally conductive substrate - Google Patents

Description

  The present invention relates to a heat conductive substrate (high heat dissipation substrate) used for a high power circuit or the like in an electronic device and a method for manufacturing the same.

  A conventional method for producing a heat conductive substrate is a method in which a sheet-shaped thermosetting resin composition in which a heat conductive filler is filled in a thermosetting resin and a circuit forming conductor are polymerized, and then heated and pressed to be integrated. Yes. The conventional method for manufacturing a thermally conductive substrate will be described with reference to the drawings.

  In FIG. 12, 51 is a sheet-shaped thermosetting resin composition, which is composed of, for example, 70 to 95 parts by weight of an inorganic filler and 5 to 30 parts by weight of at least a thermosetting resin, a curing agent and a curing accelerator, and is semi-cured. Alternatively, a doctor blade method, a coater method, an extrusion method, or a rolling method so as to have flexibility in a partially cured state and at least a film thickness of 0.8 to 2 mm, preferably 0.8 to 1.6 mm. It is formed by.

  52 is a circuit forming conductor (lead frame) processed into a predetermined pattern or shape by press processing, etching processing, laser processing or the like, and has conductivity and aluminum, copper, silver, iron or alloy materials thereof. At least the side surface of the thermosetting resin composition 51 of the thermally conductive metal plate is roughened to improve adhesion. Thereafter, a solder resist is printed on the upper surface side, and thereafter, this is cured by heat or ultraviolet rays to form a predetermined pattern for an electronic component to be mounted in a subsequent process.

  Reference numeral 53 denotes a heat radiating metal plate, which is formed by processing a metal material such as iron, copper, aluminum, anodized aluminum having excellent thermal conductivity, or an alloy thereof into a predetermined shape.

  Reference numeral 54 denotes an external connection terminal formed from the circuit forming conductor 52 by bending or the like.

  A conventional method for manufacturing a heat conductive substrate will be described with reference to FIG. That is, in FIG. 13, reference numeral 1 denotes a thermosetting resin composition that becomes a heat conductive sheet-like product obtained by forming a soft thermosetting composition containing a thermosetting resin and a heat conductive filler as components into a sheet shape. 2 is a circuit-forming conductor having a plurality of through-grooves 3 for constituting wirings, electrodes or lead terminals, and is made of a plate such as iron, copper, aluminum or alloys thereof having high thermal conductivity or high conductivity. Made of metal. Reference numeral 4 denotes a terminal for connection or heat radiation formed by bending a part of the circuit forming conductor 2.

  First, the thermosetting resin composition 1 and the circuit forming conductor 2 shown in FIG. 13A are overlapped with the thermosetting resin composition 1 on a predetermined position of the circuit forming conductor 2 as shown in FIG. 13B. Laminate together. Furthermore, as shown in FIG.13 (c), the metal plate 7 for heat dissipation is piled up on the upper surface of the thermosetting resin composition 1, and is laminated | stacked.

  Thereafter, as shown in FIG. 13 (d), the heat-dissipating metal plate 7, the thermosetting resin composition 1 and the circuit forming conductor 2 are simultaneously pressed all over, and a part of the thermosetting resin composition 1 is applied to the circuit forming conductor 2. Then, the thermosetting resin composition 1 is thermoset to be integrated with the circuit forming conductor 2 and the heat radiating metal plate 7.

  Thereafter, as shown in FIG. 13 (e), unnecessary portions of the circuit forming conductor 2 are cut and removed, and the terminals 4 are formed by bending, thereby completing the thermally conductive substrate.

In the conventional method for producing a heat conductive substrate, since the thermosetting resin composition is softened and flows when heated and pressed, the circuit forming conductor is moved by the softening and flow. .

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a heat conductive substrate capable of reliably positioning a circuit forming conductor.

In order to achieve this object, a method for manufacturing a thermally conductive substrate according to the present invention includes a circuit forming conductor, a floating island in which a part of the circuit forming conductor is independent, the circuit forming conductor, and the floating island. One or a plurality of connecting bars made of a part of the circuit forming conductor, and the circuit forming conductor, the floating island, and the connecting bars are embedded on a heat radiating metal plate. The sheet-like thermosetting resin composition to be integrated is integrated by heating and pressing in a mold, and a space is formed on both sides of the connecting beam, and a cutting body is positioned in the space And removing the connecting beam from one side of the space portion to the other side by the cutting body after the circuit portion is formed, and the circuit forming conductor and the floating island are formed by minimizing a cutting portion. Create heat conductive substrate with reliable positioning Kill.

  As described above, according to the method for manufacturing a thermally conductive substrate of the present invention, there is an effect that the positioning of the circuit forming conductor can be ensured.

  Hereinafter, a thermally conductive substrate and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the drawings.

  Next, the thermally conductive substrate of the present invention and the manufacturing method thereof will be described with reference to FIGS. 1 to 11, reference numeral 1 denotes a part of the thermosetting resin composition of FIG.

  2 is a part of the circuit forming conductor of FIG. 13 made of a metal plate material such as copper or its alloy formed in a predetermined pattern by pressing, etching or laser processing, and 5 is electrically independent called floating island. A connecting cross for connecting the lands 6, and 3 is a through groove.

  FIG. 1A is a plan view of a state in which the circuit forming conductor 2 and the thermosetting resin composition 1 are integrally molded. FIGS. 1B and 1C are views as seen from the A direction. 7 is a metal plate for heat dissipation. As shown in FIG. 1C, the connecting beam 5 can be cut and removed more easily by reducing the thickness of a part of the metal plate material to be the circuit forming conductor 2 in advance by etching or cutting. . Further, if the connecting bar 5 is cut and removed in a state where the thermosetting resin composition 1 is cured, the circuit forming conductor 2 is not easily displaced or peeled off due to stress due to processing, but the hardness of the thermosetting resin composition 1 is low. Since it is high, there is a disadvantage that the cutting tool is easily worn. Therefore, wear of the tool for cutting is performed by processing the thermosetting resin composition 1 in a semi-cured state in which the wear of the tool does not occur while preventing the circuit forming conductor 2 from being displaced or peeled off due to stress. Can be reduced.

  FIG. 2A is a perspective view of a thermally conductive substrate formed by providing projections on a molding die so that the thermosetting resin composition 1 does not flow into the side surfaces of the connecting bars 5 of the floating island 6. Spaces 8 are provided on both side surfaces of the connecting bar 5, and a tool 9 for cutting is placed in the space 8 and moved horizontally to minimize the tool 9 from scraping the thermosetting resin composition 1. Can be made. The cutting state is shown in FIGS. 2 (b) and 2 (c) with respect to FIGS. 1 (b) and 1 (c).

  FIGS. 3A and 3B are schematic views showing a state in which the connecting bar 5 is deleted by stamping after being cured or semi-cured. Reference numeral 10 denotes a punch, and FIG. 3B shows a case where the heat radiating metal plate 7 is provided. In this case, a through hole through which the punching punch 10 is passed is provided in advance in the heat radiating metal plate 7. Further, as described in the explanation of FIG. 1, if the punching is performed in a semi-cured state, the wear of the punching punch 10 can be reduced.

  In FIG. 3, when punching the connecting bar 5 of the floating island 6, it is advantageous for molding stability to punch from the back side toward the component mounting surface. By punching from the back side toward the component mounting surface, the burr comes out toward the component mounting surface. This is because the burr functions to stop the thermosetting resin composition 1 from flowing on the component mounting surface of the circuit forming conductor 2 during molding.

  FIG. 4 shows a state where the circuit-forming conductor 2 is positioned and held by being sucked by a vacuum suction hole 18 provided in the mold. Here, the lower mold in the molding die is formed by a combination of blocks 16 and 17 and has a suction port 19.

  FIG. 5 shows a state in which the circuit forming conductor 2 is positioned and held within a certain range by being fitted into a recess that is slightly larger than the circuit forming conductor 2 provided in the mold. FIG. 5A is a side view, and FIG. 5B is a perspective view. FIG. 5C is a cross-sectional view of the molded product. According to this method, the floating island 6 can be positioned, but the surface of the thermosetting resin composition 1 group located on the outer periphery of the floating island 6 becomes concave after molding. As a result, the melted solder may flow in, and the insulating distance between the lands in the circuit forming conductor 2 and the floating island 6 may be shortened.

  FIG. 6 shows a state in which the floating island 6 of the circuit forming conductor is positioned and held by four protrusions provided in the mold. Reference numeral 6-1 denotes a portion not subjected to resist printing, and cream solder may be applied. Reference numeral 6-2 denotes a portion where the cream solder is not applied in the resist-printed portion. Each protrusion 12-1 is provided in a portion that does not contact 6-1. Thereby, since the outer periphery of the floating island 6 excluding the portion provided with the protrusions 12-1 is formed by being filled with the thermosetting resin composition 1, it is possible to prevent the molten solder from flowing into the recess.

  FIG. 7 shows that the floating island 6 of the circuit forming conductor is inserted into a hole 6-3 provided in the floating island 6 and a projection 12-2 having a shape substantially the same as that of the hole is fitted and positioned and held at the same time. The state where the outer periphery of the floating island 6 is positioned by two protrusions is shown. Reference numeral 6-1 denotes a portion not subjected to resist printing, and cream solder may be applied. 6-2 is a portion where cream solder is not applied in a resist-printed portion. Each protrusion is provided in a portion that does not contact 6-1. Thereby, since the thermosetting resin composition 1 is filled and formed on the outer periphery of the portion 6-1 where the resist is not printed after the molding, it is possible to prevent the molten solder from flowing into the recess.

  FIG. 8 shows a state where the adhesive 20 is embedded in the through groove 3 around the floating island 6 of the circuit forming conductor 2. After the adhesive 20 is cured, the connecting bar 5 is removed and molded. The adhesive 20 is preferably made of the same material as the thermosetting resin composition 1 if possible.

  FIG. 9 is a schematic diagram of a process of removing the connecting beam 5 by etching after applying a resist 21 to a portion of the molded circuit board conductor 2 other than the connecting beam 5 of the floating island 6. FIG. 9A shows a state where a resist is applied to a molded product, and FIG. 9B shows a state after etching. According to this method, stress applied to the circuit forming conductor 2 is smaller than punching or cutting, and deformation can be suppressed.

  FIG. 10 (a) shows that the connecting beam 5 of the floating island 6 of the circuit forming conductor 2 is punched and removed by the upper die 27 having a built-in punch 24 for cutting the connecting beam 5 and the lower die 26 having a vacuum suction function. Shows the situation. FIG. 10B shows a heat dissipation structure in which the lower mold 26 is placed on a block 32 and the upper mold 29 is placed and the thermosetting resin composition 1 laminated on the circuit forming conductor 2 is pasted by the middle mold 30. The state which presses the metal plate 7 and tries to shape | mold is shown. The block 32 is provided with a pillar 31 for filling the punched hole 28 of the lower mold 26. The attracting surface of the lower die 26 is dug in a shape slightly larger than each land of the circuit forming conductor 2, so that the positioning and holding of the land, particularly the floating island 6, can be made more reliable. Moreover, since the vacuum suction at the time of shaping | molding may wrap around to the lower surface of the circuit formation conductor 2, when the viscosity of the thermosetting resin composition 1 is too low, it is desirable to adjust suction force according to a case.

  In the method of FIG. 10, since a part of a die for punching the connecting bar 5 of the floating island 6 also serves as a molding die, work handling is troublesome. That is, the temperature of the mold is increased during molding, but the temperature needs to be decreased during punching. It is not an easy task to combine the lower mold 26 with the block 32 having many columns 31. From these facts, the method shown in FIG. 11 improves the workability. FIG. 11 (a) shows that the connecting beam 5 of the floating island 6 of the circuit forming conductor 2 is punched and removed by the upper die 27 having a built-in punching punch 24 for cutting the connecting beam 5 and the lower die 26 having a vacuum suction function. Shows the situation. FIG. 11B shows a situation in which the circuit forming conductor 2 having been cut off the connecting bar 5 on the lower mold 26 is sucked and received by the suction block 33. FIG. 11 (c) shows a situation where it is set in the mold 34 and molding is attempted.

(A)-(c) is a schematic plan view and sectional drawing explaining the heat conductive board | substrate in this Embodiment, and its manufacturing method. (A)-(c) is a schematic perspective view and sectional drawing explaining the heat conductive board | substrate in the other embodiment, and its manufacturing method (A), (b) is schematic sectional drawing explaining the heat conductive board | substrate in the other embodiment, and its manufacturing method Schematic diagram for explaining the thermal conductive substrate and its manufacturing method in the other embodiment (A)-(c) is a schematic diagram explaining the heat conductive substrate in the other embodiment, and its manufacturing method. Schematic diagram for explaining the thermal conductive substrate and its manufacturing method in the other embodiment Schematic diagram for explaining the thermal conductive substrate and its manufacturing method in the other embodiment Schematic plan view for explaining a thermally conductive substrate and its manufacturing method in the other embodiment (A), (b) is schematic sectional drawing explaining the heat conductive board | substrate in the other embodiment, and its manufacturing method (A), (b) is the schematic diagram explaining the heat conductive board | substrate in the other embodiment, and its manufacturing method. (A)-(c) is a schematic diagram explaining the heat conductive substrate in the other embodiment, and its manufacturing method. Cross section of thermal conductive substrate (A)-(e) is a schematic diagram explaining the manufacturing method of the conventional heat conductive board | substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,51 Thermosetting resin composition 2,52 Circuit forming conductor 3 Through groove 4 Terminal 5 Connecting bar 6 Floating island 6-1 Soldered part 6-2 Resist printed part 6-3 Positioning hole 7 Heat radiation Metal plate 8 Space 9 Cutting tool 10 Punch punch 12 Lower mold 12-1 Positioning protrusion 12-2 Positioning protrusion 16 Block 17 Block 18 Suction hole 19 Suction port 20 Adhesive 21 Resist 24 Punch punch 26 Lower mold 27 Upper mold 28 Punching hole 29 Upper mold 30 Medium mold 31 Pillar 32 Block 33 Suction block 34 Molding mold 53 Metal plate for heat dissipation 54 External connection terminal

Claims (1)

A circuit forming conductor, a floating island in which a part of the circuit forming conductor is independent, and a part of the circuit forming conductor that connects the circuit forming conductor and the floating island for position maintenance. One or a plurality of connecting bars, a sheet-like thermosetting resin composition in which the circuit forming conductor, the floating island, and the connecting bars are embedded and integrated on a metal plate for heat dissipation, are heated in a mold. The step of forming the space portion on both sides of the connecting beam by applying pressure, and the cutting of the connecting beam from one side of the space portion to the other side after positioning the cutting body in the space portion And a step of deleting by the body.

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