Method for manufacturing circuit board

Abstract

To obtain a resin molding circuit body of a circuit board that can be achieved while suppressing swelling of an insulation layer and suppressing generation of cracks.SOLUTION: A circuit board includes a circuit 3 arranged in accordance with a circuit pattern and a resin mold unit 5 for covering a peripheral side surface 3c of the circuit 3. With the circuit 3, front and back circuit surfaces 3a, 3b are exposed from resin surfaces 5a, 5b of the resin mold unit 5. A bonding surface 1b for bonding to an insulation layer 27 is formed by the circuit surfaces 3a, 3b and resin surfaces 5a, 5b. The resin molding circuit body 1 includes the circuit surface 3b and the resin surface 5b of a bonding surface 1b in the insulation layer 27 on a metal substrate 25 in a face-to-face fashion.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a resin molded circuit body used in a circuit board such as a metal base circuit board, a mold for molding the resin molded circuit body, a method for manufacturing the resin molded circuit body, and a circuit board using the resin molded circuit body. [Background technology]

[0002] A conventional metal base circuit board 101 is completed by applying pressure and heat as shown in Fig. 20. For example, circuits 107... are attached to uncured insulating layer 105 of metal board 103 according to circuit pattern 107, and then the resulting product is subjected to pressure / heat treatment by pressure / heat plates 111, 113 via flat pressing tool 109, and insulating layer 105 is heated and cured.

[0003] However, as shown in Figures 21 and 22, cracks Cr occur in the insulating layer 105 at the rising portions of the circuits 107·· from the insulating layer 105, and protrusions 105a occur in the insulating layer 105 between the circuits 107··, resulting in problems such as voids V in the insulating layer 105.

[0004] In addition, there is a problem in that gaps GA occur due to misalignment of the circuits 107···.

[0005] In addition, when a circuit is punched out from a copper plate material by top and bottom precision punching, sagging Du occurs at the corners as shown in circuit 107··· in Figure 23, and this sagging Du causes the problem of a gap GA occurring after insulating layer 105 is hardened by pressurization and heating.

[0006] In particular, in order to improve the insulation reliability of metal-based circuit boards for power devices, it is important to improve the adhesion conditions of the circuits 107... to the insulating layer 105, which affects the withstand voltage.

[0007] On the other hand, in the manufacturing method of FIG. 20, when the pressure is reduced, voids existing in insulating layer 105 are not compressed and remain, so the range for improving the adhesion conditions is narrow, and improvement of robustness is essential.

[0008] In order to address this issue, a method for manufacturing a circuit board as shown in FIG. 24 described in Patent Document 1 has been proposed.

[0009] The method for manufacturing this circuit board includes the steps of arranging circuits 107... on insulating layer 105 of a metal substrate, arranging a mold 115 having convex portions 115a corresponding to the shape of the spaces between circuits 107... such that convex portions 115a are positioned in the spaces, applying pressure and heat to mold 115, and removing mold 115.

[0010] In this method, pressure is applied while the convex portions 115a of the mold 115 are positioned between the circuits 107..., so that the positional misalignment of the circuits 107... is small, and the protrusions 115a of the mold 115 suppress the bulging of the insulating layer 105 between the circuits 107..., which is thought to also suppress the occurrence of cracks.

[0011] However, in this method, the circuits 107... are contained within the recesses 115b... of the mold 115, and the recesses 115b... of the mold 115 are sealed by applying pressure, making it difficult to pull the mold 115 out of the circuits 107..., and there were problems with its feasibility. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Publication 2018-182010 Summary of the Invention [Problem to be solved by the invention]

[0013] The problem to be solved is that although it may be possible to suppress problems such as swelling and cracks in the insulating layer, it is difficult to set and remove the mold, making it difficult to implement. [Means for solving the problem]

[0014] The present invention aims to make it possible to suppress the rise of the insulating layer between circuits while suppressing the occurrence of cracks in the insulating layer.

[0015] In order to achieve this object, the resin molded circuit body of the present invention comprises a circuit arranged according to a circuit pattern, and a resin molded portion covering the peripheral side surface of the circuit, wherein at least a portion of the front and back circuit surfaces of the circuit are exposed from the resin surface of the resin molded portion, and one of the front and back circuit surfaces and the resin surface serves as a bonding surface for bonding to an insulating layer.

[0016] The mold used in the manufacture of the resin molded circuit body of the present invention is a mold for transfer molding a resin molded circuit body having a circuit arranged according to a circuit pattern and a resin molded portion covering the peripheral side surface of the circuit to be joined to an insulating layer, and is characterized in that it includes a first split mold which forms one side of a cavity for molding the resin molded circuit body, has a side periphery of the cavity that is sized according to the outer peripheral surface of the resin molded circuit body or is larger than the outer peripheral surface of the resin molded circuit body, and the first split mold is equipped with a positioning portion for positioning the circuit within the cavity.

[0017] The manufacturing method of the resin molded circuit body of the present invention is characterized in that the circuit is positioned and placed in a positioning portion of the first split mold, the cavity is formed including the first split mold, and resin that flows due to preheating is pressed into the cavity and then hardened.

[0018] The circuit board of the present invention is characterized in that the resin molded circuit body has a circuit surface and a resin surface of the joining surface that are face-to-face with an insulating layer on a substrate. Effect of the Invention

[0019] According to the resin molded circuit body of the present invention, the circuits positioned according to the circuit pattern can be handled as a single unit as a resin molded circuit body, and by expanding this into planned production activities, it can contribute to the realization of stable production.

[0020] The resin molded circuit body that maintains the accurate circuit pattern can be stocked as is.

[0021] The resin-molded circuit body can be made flat, which allows for space-efficient storage, and can be integrated into a flat plate, which allows for easy handling when transporting the circuit body in and out.

[0022] Since the resin molded circuit body maintains the circuit pattern by the resin molded portion, it can accommodate even circuits having a floating island shape in the circuit pattern.

[0023] In response to the need for large current, even thick circuits, for example those having a thickness of more than 0.5 mm, can be punched out by precision punching, which can improve the processing speed and better meet the need for cost reduction. In this case, although there is sagging on the immediate peripheral surface of the circuit, a bonding surface molded to be almost flat by the resin molded portion can be obtained. By using the mold of the present invention, it is possible to easily obtain a resin molded circuit body having a circuit arranged according to the circuit pattern by removing the resin molded circuit body from the mold or cutting the resin molded circuit body from the semi-finished product removed from the mold.

[0024] The method for producing a resin-molded circuit body of the present invention uses the mold to mold a circuit that has been positioned and arranged according to a circuit pattern, and the molded circuit body is then molded with a resin molded part, thereby easily producing a resin-molded circuit body having exposed circuit surfaces on the front and back sides and a flat bonding surface on one of the front and back circuit surfaces and the resin surface.

[0025] In a circuit board using the resin molded circuit body of the present invention, since the resin molded circuit body is pressurized including the circuit, the stress caused by the pressurization applied to the circuit is dispersed throughout the entire resin molded portion and transmitted to the insulating layer, suppressing swelling of the insulating layer around the circuit and suppressing the occurrence of cracks, thereby improving insulation reliability. Since the resin molded portion of the resin molded circuit body remains intact on the circuit board, the positional accuracy of the circuit can be easily maintained even after pressurization.

[0026] In addition, as a circuit board, the presence of resin around the circuit increases the insulation of the circuit. The resin around the circuit provides high insulation, making it possible to increase the circuit density even for multiple circuits and to reduce the size of the circuit board. Heat generated by circuit elements connected to the circuit is efficiently conducted by the resin around the circuit, improving heat dissipation performance. [Brief description of the drawings]

[0027] [Figure 1] 1 is a cross-sectional view of a resin molded circuit body (Example 1). [Diagram 2] FIG. 1 is a plan view of a resin molded circuit body (Example 1). [Diagram 3] FIG. 1 is a perspective view of a resin molded circuit body (Example 1). [Figure 4] 1 is an enlarged cross-sectional view of a main part showing the relationship between a circuit and a resin molded portion (Example 1). [Diagram 5] 1 is a cross-sectional view of a mold used in a method for producing a resin-molded circuit body (Example 1). [Figure 6] FIG. 1 is a conceptual diagram of a pressurizing / heating process for a metal base circuit board using a resin molded circuit body (Example 1). [Figure 7] 1 is a cross-sectional view of a metal base circuit board according to an embodiment of the present invention. [Figure 8] FIG. 1 is an explanatory diagram indicating an enlarged portion in a cross-sectional view of a metal base circuit board according to an embodiment using a resin molded circuit body (Example 1). [Figure 9] 12 is an enlarged photograph of the enlarged portion indicated in FIG. 11 (Example 1). [Figure 10] FIG. 13 is an explanatory diagram indicating an enlarged portion in a cross-sectional view of a metal base circuit board of a comparative example having no resin mold portion (comparative example). [Figure 11] (A) is an explanatory photograph indicating a portion to be further enlarged in the enlarged portion indicated in FIG. 13. (B) is an enlarged photograph of the enlarged portion indicated in (A). (Comparative Example) [Figure 12] FIG. 1A is an explanatory diagram showing measurement points of withstand voltage in a plan view of a metal base circuit board 29. FIG. 1B is a diagram showing the withstand voltage at the measurement points. (Example 1) [Figure 13] 13 is an enlarged cross-sectional view of a main part of a metal base circuit board 29 employing a modified circuit (Example 1). [Figure 14] 6 is a cross-sectional view of a mold used in a method for producing a resin-molded circuit body according to an embodiment of the present invention; [Figure 15] 1 and is a cross-sectional view of a resin-molded circuit body according to a second embodiment of the present invention. [Figure 16] 6 is a cross-sectional view of a mold used in a method for producing a resin-molded circuit body according to a third embodiment of the present invention, corresponding to FIG. 5. [Figure 17] 1 and is a cross-sectional view of a resin-molded circuit body according to a third embodiment of the present invention. [Figure 18] 6 is a cross-sectional view of a mold used in a method for producing a resin-molded circuit body, corresponding to FIG. 5 (Example 4). [Figure 19] 1 and is a cross-sectional view of a resin-molded circuit body according to a fourth embodiment of the present invention. [Figure 20] 6 is a cross-sectional view of a mold used in a method for producing a resin-molded circuit body, corresponding to FIG. 5 (Example 5). [Figure 21] 21 is a cross-sectional view of the resin-molded circuit body taken along the line XXI-XXI in FIG. 22, corresponding to FIG. 1 (Example 5). [Figure 22] FIG. 11 is a plan view of a resin molded circuit body having circuits crossed in a bridge shape (Example 5). [Diagram 23] FIG. 11 is a rear view of a resin molded circuit body having circuits crossed in a bridge shape (Example 5). [Figure 24]FIG. 1 is a conceptual explanatory diagram showing a conventional pressurizing / heating process for a metal base circuit board (conventional example). [Diagram 25] FIG. 1 is a cross-sectional view showing the relationship between a circuit that does not have a resin molded portion and an insulating layer (conventional example). [Figure 26] FIG. 1 is a cross-sectional view showing the relationship between a circuit that does not have a resin molded portion and an insulating layer (conventional example). [Figure 27] FIG. 1 is a cross-sectional view showing the relationship between a circuit that does not have a resin molded portion and an insulating layer (conventional example). [Figure 28] FIG. 1 is a cross-sectional view showing a process of pressing a circuit pattern using a mold (conventional example). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The objective of making it possible to suppress the protrusion of the insulating layer while suppressing the occurrence of cracks in the insulating layer was realized as follows.

[0029] The resin molded circuit body of the present invention comprises a circuit arranged according to a circuit pattern, and a resin molded portion covering the peripheral side surface of the circuit, wherein at least a portion of the front and back circuit surfaces of the circuit are exposed from the resin surface of the resin molded portion, and one of the front and back circuit surfaces and the resin surface serves as a bonding surface for bonding to an insulating layer.

[0030] At least one of the front and rear circuit surfaces of the circuit protrudes from the resin molded portion.

[0031] The circuits may be provided in multiple locations at a uniform height or at different heights.

[0032] The present invention is a mold for transfer molding a resin molded circuit body having a circuit arranged according to a circuit pattern and a resin molded portion covering the peripheral side surface of the circuit to be joined to an insulating layer, the molded circuit body including a first split mold forming one side of a cavity for molding the resin molded circuit body, the cavity having a side periphery that is sized according to the outer peripheral surface of the resin molded circuit body or that is larger than the outer peripheral surface of the resin molded circuit body, and the first split mold including a positioning portion for positioning the circuit within the cavity.

[0033] The positioning portion is an adhesive layer, a positioning pin, or a countersink provided on the first split mold on one side of the cavity.

[0034] The manufacturing method of the resin molded circuit body of the present invention positions and places the circuit in a positioning portion of the first split mold, forms the cavity including the first split mold, and presses resin that flows due to preheating into the cavity and then hardens.

[0035] The circuit board according to the present invention includes the resin-molded circuit body, and the circuit surface and resin surface of the bonding surface are fitted to an insulating layer on a substrate. EXAMPLES

[0036] [Resin molded circuit body] Fig. 1 is a cross-sectional view of a resin-molded circuit body, Fig. 2 is a plan view of the resin-molded circuit body, and Fig. 3 is a perspective view of the resin-molded circuit body.

[0037] 1 to 3, the resin molded circuit body 1 is formed, for example, in a rectangular flat plate shape, and includes a circuit 3 and a resin molded portion 5. The shape of the resin molded circuit body 1 can be freely selected to be other than rectangular, such as circular, to match the planar shape of the substrate.

[0038] Also, it is possible to configure the resin molded circuit body 1 so that lead terminals and the like are pulled out integrally therewith.

[0039] The circuits 3 are arranged according to a circuit pattern. In this embodiment, the circuit pattern includes a plurality of electrically independent circuits 3.... The configuration of the plurality of circuits 3... is formed according to the required characteristics of the circuit pattern. In the first embodiment, the circuit pattern has a floating island portion in the center. It is also possible to make the circuit pattern have no floating island portion. It is also possible to configure the circuit pattern with a single circuit 3.

[0040] The circuits 3··· are formed of, for example, copper. The circuits 3··· are formed of a copper material for circuits having a thick copper pattern with a thickness of more than 0.5 mm. The thickness of the circuits 3 can be selected from various thicknesses, and may be less than 0.5 mm.

[0041] The circuit 3 has flat circuit surfaces 3a and 3b on the front and back. In this case, the side to be bonded to an insulating layer described later is the back circuit surface 3b, and the side opposite the insulating layer to which a circuit element is bonded is the front circuit surface 3a. These terms "front and back" are used for convenience, and the side to be bonded to an insulating layer may be called the front, and the side opposite the insulating layer to which a circuit element is bonded may be called the back.

[0042] The circuit surfaces 3b... form a common plane among the multiple circuits 3. Therefore, in this embodiment, the circuit surface being flat means both that each surface of the circuit surfaces 3b... is flat among the multiple circuits 3 and that the circuit surfaces 3b... form a common plane. However, in an embodiment in which there is a single circuit 3, this means that the single circuit surface 3b forms a plane.

[0043] In the present embodiment 1, the same applies to the front circuit surfaces 3a....

[0044] However, it is sufficient that at least the rear circuit surface 3b... of the circuits 3, which is to be bonded to an insulating layer described later, is flat. Therefore, the rear circuit surface 3b..., which is to be bonded to an insulating layer, forms a common plane among the multiple circuits 3, but the circuit surface 3a... on the opposite insulating layer side can be set to different heights among the multiple circuits 3, as described later.

[0045] That is, in addition to the configuration in which a plurality of circuits 3·· are provided at a uniform height as in the first embodiment, a plurality of circuits 3··· may be provided at different heights as described later.

[0046] The peripheral side surface 3c of the circuit 3 is formed by wire cutting, etching, shaving by precision shearing, etc., so that the front and back circuit surfaces 3a, 3b are perpendicular to the peripheral side surface 3c, and the corners between the circuit surfaces 3a, 3b and the peripheral side surface 3b are formed at right angles. However, as described later, a form having droops at the corners may also be applied.

[0047] The resin molded portion 5 covers each peripheral side surface 3b of the circuits 3, and forms the overall rectangular shape of the resin molded circuit body 1.

[0048] The resin material used for the resin molded portion 5 is a resin that becomes fluid when heated and can be used for filling in the transfer molding process described below. In this embodiment 1, the same material as the insulating layer on the metal substrate described below, for example, an epoxy resin, is used to improve adhesion to the insulating layer.

[0049] Other examples of the resin material used for the resin molded portion 5 include thermosetting resins such as phenol resin, urea resin, melamine resin, urethane resin, silicone resin, unsaturated polyester resin, acrylic resin, imide resin, and amide-imide resin.

[0050] The resin used for filling may be composed of only one type, or may be composed of a combination of two or more types. From the viewpoint of electrical insulation and adhesiveness, the resin used for filling preferably contains at least one type selected from the group consisting of epoxy resin, silicone resin, amide-imide resin, and urethane resin, and from the viewpoint of moisture resistance, it preferably contains at least one type selected from the group consisting of epoxy resin, acrylic resin, and amide-imide resin.

[0051] The resin used for filling may contain components other than resin, such as fillers (powder, fibers, etc.), if necessary. In this embodiment, the epoxy resin contains about 80 to 85 wt% of silica inorganic filler in order to control the thermal expansion coefficient and fluidity, and the thermal expansion coefficient is set to be about the same as that of the copper circuit 3...

[0052] Similarly, other fillers may be included, such as inorganic materials, such as alumina, boron nitride, aluminum nitride, carbon fiber, glass fiber, and the like.

[0053] These fillers may be contained alone or in combination of two or more.

[0054] Furthermore, fillers can be added for increasing the weight, reinforcing, improving thermal conductivity, and moisture absorption. Fillers for increasing the weight include calcium carbonate, talc, silica, clay, etc. Fillers for reinforcing include wollastonite, potassium titanate, xonotlite, gypsum fiber, aluminum borate, MOS, aramid fiber, various fiber systems, carbon fiber, glass fiber, talc, mica, glass flakes, polyoxybenzoyl whiskers, etc. Fillers for thermal conductivity include Al2O3 (alumina), AlN, BN, BeO, etc. Fillers for moisture absorption include water-absorbing polymer gel, calcium oxide, magnesium oxide, etc.

[0055] Only one of these fillers may be added, or a combination of two or more of them may be added.

[0056] The resin material used for the resin molded portion 5 may further contain, for example, a coupling agent, a dispersant, and the like in addition to the above-mentioned matrix resin and inorganic filler.

[0057] In the resin molded portion 5, the flat resin surface 5b to be joined to the insulating layer is provided substantially along the flat circuit surfaces 3b... to be joined to the insulating layer. The flat resin surface 5a on the anti-insulating layer side is also provided along the flat circuit surfaces 3a... on the anti-insulating layer side. With this configuration, the resin molded circuit body 1 is formed into a flat plate shape as a whole.

[0058] However, it is sufficient that the circuit 3 and the resin molded portion 5 have at least the flat circuit surfaces 3b... and the resin surfaces 5b to be joined to the insulating layer, which are substantially aligned with each other. In a configuration in which a plurality of circuits 3... are provided at different heights, the resin surfaces 5a around each circuit surface 3a between the circuits 3 at different heights may have a step as described below.

[0059] In this flat-plate-like resin-molded circuit body 1, the circuits 3··· have front and back circuit surfaces 3a···, 3b··· both exposed from the resin molded portion 5.

[0060] The resin molded circuit body 1 has a bonding surface 1b formed by the rear circuit surfaces 3b... and the resin surface 5b for bonding to an insulating layer described below, and the front circuit surfaces 3a... are used as bonding surfaces for circuit elements, etc.

[0061] The resin molded circuit body 1 of this Example 1 is formed symmetrically with both sides being approximately flat, so that both sides serve as bonding surfaces for the insulating layer, and by allowing the bonding surface to be selected arbitrarily during bonding, incorrect assembly onto a metal substrate can be prevented.

[0062] For example, a configuration is also possible in which the front circuit surfaces 3a··· and resin surface 5a are used as bonding surfaces for bonding to an insulating layer, and the rear circuit surfaces 3b··· are used as bonding surfaces for circuit elements or the like.

[0063] However, the resin molded circuit body 1 may be formed asymmetrically on the front and back, with one of the front and back being specified as the bonding surface 1b and the other being specified as the bonding surface for circuit elements or the like.

[0064] FIG. 4 is an enlarged cross-sectional view of a main part showing the relationship between the circuit and the resin molded portion.

[0065] 4, in this embodiment, the circuits 3... have flat circuit surfaces 3a... and circuit surfaces 3b... on both the front and back sides that protrude from flat resin surfaces 5a and 5b on both the front and back sides of the resin molded portion 5. The protrusion amount is, for example, Pr=20 to 60 μm.

[0066] The protrusions of the circuit surfaces 3a..., 3b... on both the front and back sides are formed in anticipation of slight recession of the resin molded portion 5 after molding. With such protrusions, both the front and back sides of the resin molded circuit body 1 are made approximately flat, including the circuit surfaces 3a..., 3b... and the resin surfaces 5a and 5b.

[0067] At least one of the front and back surfaces of the resin molded circuit body 1 is flat in order to maintain adhesion to the insulating layer. Therefore, as long as adhesion can be maintained, the circuit surface 3a... or the circuit surface 3b... that constitutes the bonding surface to the insulating layer may be slightly recessed from the resin surface 5a or the resin surface 5b. However, it is preferable that the circuit surface 3a... or the circuit surface 3b... protrudes from the resin surface 5a or the resin surface 5b or that the two are formed flush with each other, as described above.

[0068] The protrusion of at least one of the circuit surfaces 3a... or circuit surfaces 3b... can be achieved by forming a countersink in the mold as described below, so that at least one of the circuit surfaces 3a... or circuit surfaces 3b... can be made to protrude from the flat resin surface 5a or resin surface 5b to form a non-flat shape.

[0069] That is, only the circuit surfaces 3a... or only the circuit surfaces 3b... can be made to protrude from the resin surface 5a or the resin surface 5b by the countersink. Both the circuit surfaces 3a... and the circuit surfaces 3b... can also be made to protrude from the resin surface 5a or the resin surface 5b by the countersink. Furthermore, a part 3a or 3b of the multiple front and rear circuit surfaces 3a... and circuit surfaces 3b... can be made to selectively protrude from the resin surface 5a or the resin surface 5b.

[0070] [Mold] FIG. 5 is a cross-sectional view of a mold used in the method for producing a resin molded circuit body.

[0071] As shown in Fig. 5, the mold 7 is for transfer molding the resin molded circuit body to be bonded to the insulating layer. As shown in Fig. 1, the resin molded circuit body 1 includes the circuits 3... arranged according to the circuit pattern and the resin molded portion 5 covering the peripheral side surface 3c of the circuits 3...

[0072] In the first embodiment, the mold 7 is configured by combining four parts, namely, first, second, third and fourth split molds 9, 11, 13 and 15. The first, second and third split molds 9, 11 and 13 form a cavity 17 for molding the resin molded circuit body 1. The fourth split mold 15 forms a transfer chamber 19.

[0073] The first split mold 9 constitutes one side of the cavity 17 corresponding to one side of the resin molded circuit body 1. The first split mold 9 also has an adhesive layer 21 as a positioning portion for positioning the circuit 3 in the cavity 17. Instead of the adhesive layer 21, a positioning pin, a countersink, or the like can also be used as the positioning portion, as described below.

[0074] The positioning portion can be provided in the second split mold 11. In the case where the positioning portion is an adhesive layer 21, a countersink, or the like that does not significantly affect the function of the joining surface 1b of the resin molded circuit body 1, the positioning portion can be provided in both the first and second split molds 9, 11.

[0075] In the embodiment, adhesive layer 21 as a positioning portion is provided on the surface inside cavity 17 of first split mold 9, but it may be provided so as to cover the entire upper surface including the surface inside cavity 17 of first split mold 9, with the peripheral portion of adhesive layer 21 being interposed between the layers of first and third split molds 9, 11. The same applies when adhesive layer 21 is provided on second split mold 11. However, when adhesive layer 21 is provided on second split mold 11, it is formed so as not to block gate 11a.

[0076] The adhesive layer 21 may be provided either in a fixed manner on the first separate mold 9 or in a detachable manner.

[0077] The surface of the first split mold 9 on the cavity 17 side is entirely flat. A double-sided or single-sided adhesive tape using a heat-resistant silicone, acrylic, or urethane adhesive is used as the adhesive layer 21. The base material of the adhesive tape is preferably a PET film, an imide film, a metal foil (copper, aluminum), or the like.

[0078] The second split mold 11 constitutes the other side of the cavity 17 corresponding to the other side surface of the resin molded circuit body 1. In addition, the second split mold 11 is provided with a gate 11a that comes into contact with the circuit surface of the circuit 3 in the cavity 17 and serves as a passage for resin.

[0079] The surface of the second split mold 11 facing the cavity 17 is formed as a flat surface overall. However, depending on the specifications of the resin molded circuit body 1, the surface of the second split mold 11 facing the cavity 17 can also be made uneven. The gap between the cavity 17 formed by the first and second split molds 9, 11 can be made relatively narrow at the gate 11a to increase the flowability of resin into the entire cavity 17.

[0080] The third split mold 13 has flat upper and lower surfaces, a lower surface which is positioned and joined to the upper surface of the first split mold 9, and a lower surface of the second split mold 11 which is positioned and joined to the upper surface to form a cavity 17. The thickness of the third split mold 13 is approximately the same as that of the circuit 3 in Example 1, and the vertical dimensions of the cavity 17 above the adhesive layer 21 are approximately the same as that of the circuit 3.

[0081] In this way, the third split mold 13 is interposed between the first and second split molds 9, 11 and forms a side periphery 17a of the cavity 17 with a size corresponding to the outer circumferential surface of the resin molded circuit body 1. In this case, the product removed from the cavity 17 becomes the resin molded circuit body 1 (FIG. 1).

[0082] However, the third split mold 13 may form the side periphery of the cavity 17 with a size larger than the outer peripheral surface of the resin molded circuit body 1. The side periphery of the cavity 17 larger than the outer peripheral surface of the resin molded circuit body 1 is intended to form the semi-finished product of the resin molded circuit body 1 to be one size larger, including the part of the resin molded circuit body 1. In this case, the resin molded circuit body 1 is cut out from the semi-finished product.

[0083] The fourth split mold 15 is joined to the outer surface of the second split mold 11 to form the transfer chamber 19. The transfer chamber 19 communicates with the gate 11a.

[0084] It should be noted that the mold 7 is only required to be capable of transfer molding the resin molded circuit body 1, and should include the first split mold 9 which forms one side of the cavity 17 for molding the resin molded circuit body 1. Therefore, the mold is not limited to having the first to fourth split molds 9, 11, 13, and 15, and it is also possible to integrally form the second to fourth split molds 11, 13, and 15 into one mold and have a two-split configuration with the first split mold 9.

[0085] [Manufacturing method of resin molded circuit body] In manufacturing the resin molded circuit body 1, in the separated state of the first separate mold 9, the circuits 3·· are positioned and arranged on the adhesive layer 21 according to the circuit pattern.

[0086] The arrangement of the circuits 3··· can be performed by automation using image processing, but it is also possible to use, for example, a semi-finished sheet material for circuit boards that the applicant has already proposed. The circuits 3··· can also be formed by an etching process. In the etching process, a copper plate fixed to a carrier film with an adhesive or the like is chemically etched to form a circuit, which can then be used as is for transfer molding. It can also be transferred to another adhesive film as mentioned above and used in this manufacturing method.

[0087] The semi-finished circuit board plate material is in the form of a flat plate having a plurality of circuits positioned corresponding to the circuit pattern.

[0088] In other words, the areas corresponding to the multiple circuits are half-punched into the copper sheet material, and after half-punching, the areas corresponding to the multiple circuits are returned to their half-punched positions in the scrap, and the multiple circuits are fitted into and positioned in the scrap, making the whole into a flat plate, almost returning to the original shape of the copper sheet material.

[0089] This semi-finished circuit board plate material is positioned relative to the first split die 9, and is pressed out by a press or the like and transferred onto the adhesive layer 21.

[0090] Next, the first, second, third and fourth split molds 9, 11, 13 and 15 are combined to assemble the mold 7, thereby forming the cavity 17 and the transfer chamber 19. At this time, the elasticity of the adhesive layer 21 can be utilized to press and hold the circuits 3... between the first and second split molds 9 and 11.

[0091] Next, the tablet-shaped resin is placed in the transfer chamber 19. This tablet-shaped resin is preheated in the transfer chamber 19 until the resin flows. At this time, the mold 7 is heated to, for example, 180°C.

[0092] The resin 23 which flows due to the preheating is pressed by a plunger at a pressure of about 7 MPa as shown by the arrow, and the resin 23 is forced into the cavity 17 .

[0093] In addition, in terms of the pressing conditions, the preheating temperature can be set within the range of 50 to 400° C., and the pressure can be set within the range of 1 to 20 MPa, depending on the material and viscosity of the resin used.

[0094] The injected resin 23 is further heated as it passes through the gate 11a, and its viscosity decreases.

[0095] The resin 23 that has passed through the gate 11a flows within the cavity 17 and spreads throughout the space around the circuit 3. In this case, the mold 7 is provided with an air vent hole, a spare space for the resin to flow in, or the like so that the resin 23 can spread throughout the space within the cavity 17.

[0096] After that, a curing reaction is carried out for about 3 minutes, and when the resin 23 has hardened, the mold 7 is divided appropriately and the semi-finished product of the resin molded circuit body 1 is taken out. Note that the reaction time can be made shorter than 3 minutes depending on the resin composition (epoxy resin, curing agent, catalyst, curing accelerator, etc.) and molding conditions.

[0097] In this embodiment, since the side periphery 17 a of the cavity 17 is configured to have a size corresponding to the outer peripheral surface of the resin molded circuit body 1 , what is taken out of the cavity 17 becomes the resin molded circuit body 1 .

[0098] When the side periphery 17a of the cavity 17 is configured to be larger than the outer peripheral surface of the resin molded circuit body 1, what is taken out of the cavity 17 is a semi-finished product formed to be one size larger, including the portion of the resin molded circuit body 1. This semi-finished product is formed, for example, in a planar shape, such as a substantially circular shape, and has a shape that allows the resin to flow easily during molding.

[0099] In this case, the semi-finished product can be cut to obtain the rectangular resin molded circuit body 1 shown in FIGS.

[0100] In the obtained resin-molded circuit body 1, due to slight shrinkage of the resin of the resin molded portion 5 of the resin-molded circuit body 1, the circuit surfaces 3a..., 3b... protrude from the resin surfaces 5a, 5b as shown in FIG.

[0101] However, by adjusting the amount of filler contained in the resin molded portion 5, the circuit surfaces 3a···, 3b··· and the resin surfaces 5a, 5b can be set to be substantially flush with each other.

[0102] [Metal-based circuit board] FIG. 6 is a conceptual diagram of a pressurizing / heating process for a metal base circuit board using a resin molded circuit body.

[0103] 6, in the pressurizing / heating step, a pressurizing / heating treatment is performed to bond the resin molded circuit body 1 to the insulating layer 27 on the metal substrate 25. In this pressurizing / heating treatment, a pressurizing / heating plate and a flat pressing tool (see FIG. 24) are used.

[0104] When the pressure / heat plate descends, the upper surface of the resin molded circuit body 1 is pressed by the flat pressing tool, and the lower surface of the resin molded circuit body 1 is pressed against the insulating layer 27. At this time, the pressure is distributed not only to the circuit boards but also to the entire resin molded portion 5.

[0105] By this pressure application, the metal substrate 25, the insulating layer 27, and the resin molded circuit body 1 are pressed between the pressure / heating plates and heated at the same time, so that the insulating layer 27 hardens.

[0106] FIG. 7 is a cross-sectional view of a metal base circuit board.

[0107] 7 is an example of a circuit board. A resin molded circuit body 1 is used for this metal base circuit board 29. In the metal base circuit board 29, the resin molded circuit body 1 is fixed to a rectangular flat metal board 25 via an insulating layer 27 by the manufacturing method described above.

[0108] That is, the resin molded circuit body 1 has the circuit surfaces 3b... and the resin surface 5b of the joining surface 1b on the insulating layer 27 on the metal substrate 25 in face-to-face contact.

[0109] The metal substrate 25 is made of, for example, a single metal or an alloy. Examples of the material that can be used for the metal substrate 25 include aluminum, iron, copper, an aluminum alloy, and stainless steel. The metal substrate 25 may further include a nonmetal such as carbon. For example, the metal substrate 25 may include aluminum composited with carbon. The metal substrate 25 may have a single-layer structure or a multi-layer structure.

[0110] The metal substrate 25 has high thermal conductivity. For example, a copper material has a thermal conductivity of 370 to 400 W·m-1·K-1, an aluminum material has a thermal conductivity of 190 to 220 W·m-1·K-1, and an iron material has a thermal conductivity of 60 to 80 W·m-1·K-1.

[0111] The metal substrate 25 may or may not be flexible. The thickness of the metal substrate 25 is, for example, in the range of 0.2 to 5.0 mm. In this embodiment, the thickness is 2.0 mm.

[0112] The metal substrate 25 is an example of a substrate used in a circuit board, and the substrate may have a variety of shapes. Therefore, a substrate having a heat sink shape with multiple fins may be used.

[0113] The insulating layer 27 has a thickness of 120 μm, but the thickness of the insulating layer 27 can be set to various thicknesses depending on the specifications of the metal base circuit board 29.

[0114] The insulating layer 27 not only serves to electrically insulate the circuit 3 from the metal substrate 25, but also serves as an adhesive to bond them together. For this reason, a resin is generally used for the insulating layer 27. Furthermore, since the insulating layer 27 is required to have high heat resistance against the high heat generation of the elements mounted on the circuit 3 and high thermal conductivity to transfer the heat to the metal substrate 25, it is preferable that the insulating layer 27 further contains an inorganic filler.

[0115] As the matrix resin of the insulating layer 27, for example, epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, triazine type epoxy resin, etc.; cyanate resins such as bisphenol E type cyanate resin, bisphenol A type cyanate resin, novolac type cyanate resin, etc. can be used alone or in combination of two or more kinds.

[0116] The inorganic filler contained in the insulating layer 27 is preferably one having excellent electrical insulation properties and high thermal conductivity, and examples of such fillers include alumina, silica, aluminum nitride, boron nitride, silicon nitride, magnesium oxide, etc., and it is preferable to use one or more types selected from these.

[0117] The filling rate of the inorganic filler in the insulating layer 27 can be appropriately set depending on the type of inorganic filler. For example, it is preferably 85 volume % or less, and more preferably 30 to 85 volume %, based on the total volume of the matrix resin contained in the insulating layer 27.

[0118] Insulating layer 27 may further contain, for example, a coupling agent, a dispersing agent, and the like, in addition to the above-mentioned matrix resin and inorganic filler.

[0119] Alternatively, a semi-cured insulating sheet may be used as insulating layer 27.

[0120] The details of the resin molded circuit body 1 are as described above.

[0121] Fig. 8 is an explanatory diagram indicating an enlarged area IA in a cross-sectional view of a metal base circuit board 29 of an embodiment using a resin molded circuit body 1. Fig. 9 is an enlarged photograph of the enlarged area indicated in Fig. 8. Fig. 10 is an explanatory diagram indicating an enlarged area IB1 in a cross-sectional view of a metal base circuit board 31 of a comparative example having no resin molded portion. Fig. 11(A) is an explanatory photograph indicating an enlarged area IB2 in the photograph of the enlarged area IB1 indicated in Fig. 13. Fig. 11(B) is an enlarged photograph of the enlarged area IB2 indicated in Fig. 11(A).

[0122] As shown in Figures 8 and 9, in a metal base circuit board 29 (with circuit sealing) manufactured using a resin molded circuit body 1 by the above-mentioned pressure / heat treatment, the stress acting on the circuits 3... was dispersed, and no cracks were generated in the insulating layer 27 at the rising portion of the circuit 3 from the insulating layer 27.

[0123] 10 and 11, in a metal base circuit board 31 (without circuit sealing) manufactured by pressure / heat treatment of a circuit 3 not molded in a resin molded portion 5, stress was concentrated in the circuit 3..., and cracks Cr occurred in the insulating layer 27 at the rising portion from the insulating layer 27. In Fig. 11, the white particles are the filler in the insulating layer 27, and the portion IB2 in Fig. 11(A) and the enlarged photograph in Fig. 11(B) show cracks Cr in the area where the filler has not been transferred.

[0124] In addition, in the enlarged photograph of metal base circuit board 29 in Fig. 9, circuit surface 3b of circuit 3 and resin surface 5b of resin molded portion 5 (sealing resin in the photograph) are flush with each other and in contact with insulating layer 27. Even in this completed form, resin molded circuit body 1 is used in which circuit surfaces 3a..., 3b... protrude from resin surfaces 5a, 5b as shown in Fig. 4 above, and circuit surface 3b and resin surface 5b are flush with each other as a result of the pressurization / heating treatment.

[0125] This is believed to be because the resin molded portion 5 is further heated and pressurized after the circuit surfaces 3b··· of the circuits 3··· come into contact with the insulating layer 27 during pressure application.

[0126] [Voltage resistance] Fig. 12(A) is an explanatory diagram showing measurement points of withstand voltage in a plan view of the metal base circuit board 29. Fig. 12(B) is a chart showing the withstand voltage at the measurement points.

[0127] In a metal base circuit board 29 using the resin molded circuit body 1 of the embodiment as shown in FIG. 12(A), the withstand voltage was measured for circuit numbers 1, 2, 3, 4, and 5. As shown in FIG. 12(B), the withstand voltage was 9.3 kv for circuit number 1, 9.9 kv for circuit number 2, 8.7 kv for circuit number 3, 6.9 kv for circuit number 4, and 9.1 kv for circuit number 5.

[0128] In contrast, in a metal base circuit board 31 manufactured by applying pressure and heat to a circuit 3 not molded with a resin molded portion 5 as shown in FIG. 10, the withstand voltage of the circuit 3 was about 0.5 kV.

[0129] As is clear from this comparison, the metal base circuit board 29 of this embodiment was able to improve its withstand voltage.

[0130] [Modification of the circuit] FIG. 13 is an enlarged cross-sectional view of a main portion of a metal base circuit board 29 in which a modified example of the circuit 3 is employed.

[0131] The circuit 3 of this modified example is punched out by precision punching, and the peripheral side surface is not subjected to processing such as wire cutting, etching, etc. Therefore, the peripheral side surface 3c of the circuit 3 is not sharp as in Fig. 4, and has sagging Du at the corners of the edge portions Si of the upper and lower circuit surfaces 3a and 3b in part E in Fig. 13.

[0132] Even in the circuit 3 with such sagging Du, the resin of the resin molded portion 5 gets between the circuit 3 and the insulating layer 27 in the portion with the sagging Du, and the joint surface 1b of the resin molded circuit body 1 becomes almost flat. As a result, after bonding to the insulating layer 27, the occurrence of a gap between the circuit 3 and the insulating layer 27 can be suppressed.

[0133] [Effects of Example 1] Example 1 of the present invention comprises circuits 3.... arranged according to a circuit pattern, and a resin molded portion 5 covering the peripheral side surfaces 3c.... of the circuits 3...., with front and back circuit surfaces 3a..., 3b.... exposed from resin surfaces 5a, 5b of the resin molded portion 5, and one of the front and back circuit surfaces 3a..., 3b.... and the resin surfaces 5a, 5b serves as a bonding surface 1b for bonding to an insulating layer 27.

[0134] Therefore, the circuits 3... positioned according to the circuit pattern can be handled as a single unit as the resin molded circuit body 1, and by expanding this into planned production activities, it can contribute to the realization of stable production.

[0135] The resin molded circuit body 1 that maintains the accurate circuit pattern of the circuits 3... can be stocked as is.

[0136] The resin molded circuit body 1 can be made flat, and when it is made flat, it can be stored in a space-efficient manner. In addition, by making the resin molded circuit body 1 integrally in a flat plate shape, it becomes easy to handle when it is brought in and taken out.

[0137] Since the resin molded circuit body 1 maintains the circuit pattern of the circuits 3... by the resin molded portion 5, it can accommodate even floating island portions in the circuit pattern.

[0138] The circuits 3... can be formed so that the front and back circuit surfaces 3a..., 3b... protrude from the resin molded portion 5.

[0139] Therefore, when the resin molded circuit body 1 is bonded to the insulating layer 27 on the metal substrate 25 by pressure / heat treatment using a flat pressing tool or the like, pressure can be applied preferentially to the circuits 3.... As a result, the pressing force of the circuit surfaces 3b... against the insulating layer 27 becomes relatively high, which can contribute to improving the peel strength.

[0140] The circuits 3··· may be provided in a plurality at a uniform height or in a plurality at different heights.

[0141] If multiple circuits 3... are provided at a uniform height, the metal base circuit board 1 can be made flat, and if multiple circuits 3... are provided at different heights, it is possible to easily respond to variations in the metal base circuit board 1.

[0142] Even if sagging occurs at the corners of the edges of the upper and lower circuit surfaces 3a, 3b of the circuit 3 due to precision punching, the sagging parts can be covered with the resin of the resin molded part 5, making the front and back surfaces flat.

[0143] Therefore, even if sagging occurs at the corners of the edges of the upper and lower circuit surfaces 3a, 3b of the circuit 3, it is possible to accurately form a resin molded circuit body 1 which has circuit surfaces 3a..., circuit surfaces 3b... and resin surfaces 5a, 5b on the front and back, and which has a substantially flat bonding surface 1b on the back surface.

[0144] Of course, when the corners of the circuits 3... are formed at right angles, the resin molded portion 5 molds the side surfaces 3c of the circuits 3..., and the side surfaces 3c are uniformly covered with resin 23, thereby accurately forming a resin molded circuit body 1 having circuit surfaces 3a..., circuit surfaces 3b... and resin surfaces 5a, 5b and a substantially flat joint surface 1b.

[0145] Therefore, in order to meet the needs for larger currents, even thicker circuits 3..., for example circuits with a thickness of more than 0.5 mm, can be obtained by using precision punching, which can improve processing speed and better meet the needs for cost reduction.

[0146] Here, if the circuits 3... are processed by etching, it becomes difficult to narrow the mutual spacing between the circuits 3... to less than the thickness of the circuits 3....

[0147] On the other hand, in the case of precision punching or the like, the mutual spacing between the circuits 3··· can be narrowed to less than the thickness of the circuits 3···, thereby increasing the circuit density and enabling the metal base circuit board 29 to be made smaller.

[0148] Of course, precision punching can be used similarly for circuits less than 0.5 mm thick.

[0149] The mold for transfer molding the resin molded circuit body 1 includes first, second and third split molds 9, 11 and 13 for forming the cavity 17 for molding the resin molded circuit body 1, and a fourth split mold 15 for forming a transfer chamber 19. The first split mold 9 constitutes one side of the cavity 17 corresponding to one side of the resin molded circuit body 1 and includes an adhesive layer 21 as a positioning portion for positioning the circuits 3... within the cavity 17. The second split mold 11 is a mold for forming the resin molded circuit body 1. The third split mold 13 is interposed between the first and second split molds 9, 11 and forms a side periphery 17a of the cavity 17 with a size corresponding to the outer peripheral surface of the resin molded circuit body 1 or with a size larger than the outer peripheral surface of the resin molded circuit body 1. The fourth split mold 15 is joined to the second split mold 11 and communicates the transfer chamber 19 with the gate 11a.

[0150] Therefore, when the first split mold 9 is in a split state, the circuit 3 is positioned and arranged on the adhesive layer 21 exposed to the first split mold 9 according to the circuit pattern by automation using image processing or by using the semi-finished plate material for the circuit board.

[0151] Next, the first, second, third and fourth split molds 9, 11, 13 and 15 are combined to form mold 7, which forms cavity 17 and transfer chamber 19. Resin 23 that flows due to preheating is then pressed into cavity 17, and when resin 23 hardens, it can be removed as resin molded circuit body 1 or a semi-finished product of resin molded circuit body 1.

[0152] Therefore, the resin-molded circuit body 1 having the circuits 3... arranged according to the circuit pattern can be easily obtained by removing the resin-molded circuit body 1 from the mold, or by cutting the resin-molded circuit body 1 out of the semi-finished product removed from the mold.

[0153] The circuits 3... can be easily positioned relative to the adhesive layer 21 in a state in which the first split mold 9 is separated.

[0154] The thickness of the third split mold 13 is the same or nearly the same as that of the circuit 3, and the vertical dimensions of the cavity 17 can be made the same or nearly the same as that of the circuit 3, so that the circuit surfaces 3a..., 3b... can be accurately exposed on both the front and back sides of the resin molded circuit body 1.

[0155] When the third split mold 13 is configured so that the side periphery 17a of the cavity 17 is larger than the outer peripheral surface of the resin molded circuit body 1, the position of the resin flowing in from the gate 11a can be outside the semi-finished resin molded circuit body 1, thereby improving the quality of the resin molded circuit body 1.

[0156] The positioning portion is an adhesive layer 21 provided on the first separate mold 9 on one side of the cavity 17 .

[0157] Therefore, the circuits 3·· can be easily positioned and arranged on the adhesive layer 21 of the first split mold 9 by automation using image processing or by using a semi-finished plate material for a circuit board.

[0158] The manufacturing method of the resin molded circuit body 1 of this Example 1 includes positioning and arranging the circuits 3... on the adhesive layer 21 which is the positioning portion of the first separate mold 9, combining the first, second, third and fourth separate molds 9, 11, 13 and 15 including the first separate mold 9 to form the cavity 17 and transfer chamber 19, heating the mold 7, and placing tablet-shaped resin in the transfer chamber 19. This tablet-shaped resin is preheated in the transfer chamber 19 until the resin flows.

[0159] The resin 23, which has been softened by preheating until it becomes fluid, can be forced into the cavity 17 through the gate 11a by a plunger and then hardened.

[0160] In this case, the circuit 3... is sandwiched between the first and second split molds 9, 11 via the elasticity of the adhesive layer 21, and together with the adhesion of the adhesive layer 21, this ensures reliable positioning within the cavity 17.

[0161] Therefore, the circuits 3... that are positioned and arranged according to the circuit pattern can be molded in the resin molded portion 5, and the resin molded circuit body 1 having the circuit surfaces 3a..., 3b... exposed on the front and back can be easily obtained.

[0162] When the circuits 3... are partially connected to each other by bridges or the like, the front and back circuit surfaces 3a..., 3b... may be exposed from the resin surface of the resin molded portion 5, but the bridges or the like may be covered by the resin molded portion 5. The bridges or the like constitute a part of the circuit, and the front and back of the bridges or the like constitute circuit surfaces. By covering these bridges or the like with the resin molded portion 5, the circuit has a configuration in which at least parts of the front and back circuit surfaces are exposed from the resin surfaces 5a, 5b of the resin molded portion 5. This will be specifically described in Example 5 below.

[0163] When the cavity 17 has the side periphery 17a that is larger in size than the outer peripheral surface of the resin molded circuit body 1, a semi-finished product of the resin molded circuit body 1 is formed within the cavity 17, and the semi-finished product of the resin molded circuit body 1 can be removed from the cavity 17 and cut to obtain the resin molded circuit body 1.

[0164] The resin molded circuit body 1 has an insulating layer 27 on a metal substrate 25, and circuit surfaces 3b... and a resin surface 5b of a joining surface 1b are fitted together.

[0165] Therefore, the resin molded circuit body 1, including the resin molded portion 5, can be pressed against the insulating layer 27, and the pressure acting on the circuitry can be dispersed throughout the resin molded portion 5. This makes it possible to suppress the insulating layer 27 from swelling between the circuits 3, as well as to suppress the occurrence of cracks in the rising portions of the circuits 3 from the insulating layer 27, thereby improving insulation reliability.

[0166] Even when there is only one circuit 3, the insulating layer 27 is prevented from swelling around the circuit 3 and the occurrence of cracks in the rising portion of the circuit 3 from the insulating layer 27 is also prevented, similarly improving the insulation reliability.

[0167] In the resin molded circuit body 1, the resin molded portion 5 remains intact on the metal base circuit board 29, so that the positional accuracy of the circuit 3 can be easily maintained even after pressure is applied.

[0168] In addition, in the metal base circuit board 29, the resin 23 is interposed between the circuits 3..., which can improve the insulation between the circuits 3... and can also increase the circuit density. By increasing the circuit density, the metal base circuit board 29 can be made smaller.

[0169] Furthermore, heat generated by circuit elements and the like connected to the circuits 3··· is efficiently conducted by the resin between the circuits 3···, so that the overall heat dissipation performance can be improved.

[0170] This improvement in heat dissipation performance can reduce the difference in thermal expansion between the insulating layer 27, the resin molded portion 5, and the circuits 3....

[0171] The resin molded portion 5 can also serve as a measure against moisture absorption in the circuits 3···. EXAMPLES

[0172] Figures 14 and 15 show Example 2. Figure 14 corresponds to Figure 5 and is a cross-sectional view of a mold used in a manufacturing method of a resin-molded circuit body. Figure 15 corresponds to Figure 1 and is a cross-sectional view of the resin-molded circuit body.

[0173] In the present embodiment 2, a positioning pin 33 is used as a positioning portion for positioning the circuit 3 relative to the mold 7.

[0174] That is, in the first split mold 9 of this Example 2, the adhesive layer 21 serving as the positioning portion of the circuit 3 in FIG. 5 is replaced with a positioning pin 33. The positioning pin 33 protrudes from the first split mold 9 into the cavity 17. This positioning pin 33 is provided for each circuit 33. The positioning pin 33 engages with the peripheral side surface 3c of the circuit 3 with respect to the first split mold 9, and positions the circuit 3 in the XY directions with respect to the first split mold 9.

[0175] When such a positioning portion using the positioning pin 33 is employed, as shown in FIG. 15, a hole 33a where the positioning pin 33 is removed is generated in the front resin surface 5a of the resin molded circuit body 1, but no hole is generated in the back resin surface 5b of the resin molded circuit body 1, and the resin molded circuit body 1 can be bonded to the insulating layer 27 at a flat bonding surface 1b.

[0176] Furthermore, by using the positioning pins 33, the circuits 3··· can be reliably positioned within the cavity 17.

[0177] It is also possible to adopt a configuration in which the position of the positioning pin 33 can be changed. For example, a change hole is formed in the first split mold 9, and the positioning pin 33 is replaced for use. Dummy pins can be fitted into unused holes.

[0178] In addition, in the second embodiment, the same effects as those in the first embodiment can be achieved. EXAMPLES

[0179] Figures 16 and 17 show Example 3. Figure 16 corresponds to Figure 5 and is a cross-sectional view of a mold used in a method for producing a resin-molded circuit body. Figure 17 corresponds to Figure 1 and is a cross-sectional view of the resin-molded circuit body.

[0180] In the present embodiment 3, a countersink 35 is used as a positioning portion for the circuit 3 relative to the mold 7.

[0181] That is, in the first split mold 9 of this Example 3, the adhesive layer 21 serving as the positioning portion for the circuit 3 in Fig. 5 is replaced with a countersink 35. The countersink 35 is formed on the surface inside the cavity 17 of the first split mold 9. This countersink 35 is provided for each circuit 33, and the circuit surface 3b side of the circuit 3 is fitted into the first split mold 9, positioning the circuit 3 in the XY directions with respect to the first split mold 9.

[0182] The thickness of the third split mold 13 is formed to be relatively small compared to the circuit 3 , and the vertical dimension of the cavity 17 is smaller than the thickness of the circuit 3 by the depth dimension of the countersink 35 .

[0183] By employing such a positioning portion using the countersunk groove 35, the amount of protrusion of the circuit surface 3b of the resin molded circuit body 1 can be set as shown in FIG.

[0184] In this embodiment, the circuit surface 3a side has a protruding amount due to slight shrinkage of the resin of the resin molded portion 5 in Figure 4, and the circuit surface 3b side that is adhered to the insulating layer 27 can be configured so that the circuit surface 3b protrudes from the resin molded portion 5 even after the pressure / heat treatment, and the protruding circuit surface 3b protrudes into the insulating layer 27.

[0185] In a metal base circuit board 29 (see FIG. 7 for the symbol) in which the circuit surface 3b protrudes into the insulating layer 27 (see FIG. 7 for the symbol), the bonding strength between the circuits 3... and the insulating layer 27 is increased, thereby improving the peel strength.

[0186] The depth of the countersink 35 can be increased or decreased. The countersink 35 can be provided in both the first and second split molds 9 and 11, or it can be provided only in the second split mold 11.

[0187] In addition, by employing the countersink 35, the circuits 3... can be reliably positioned within the cavity 17. By setting the depth of the countersink 35, it is possible to arbitrarily set the amount by which the circuit surfaces 3b... protrude from the resin surface 5b of the resin molded portion 5. This setting improves the peel strength and also makes it possible to adjust it.

[0188] In the third embodiment as well, the same effects as those in the first embodiment can be achieved. EXAMPLES

[0189] Figures 18 and 19 show Example 4. Figure 18 corresponds to Figure 5 and is a cross-sectional view of a mold used in a manufacturing method of a resin-molded circuit body. Figure 19 corresponds to Figure 1 and is a cross-sectional view of the resin-molded circuit body.

[0190] In this Example 4, as shown in FIG. 18, a concave-convex shape was set on the surface of the second split mold 11 of the mold 7 on the cavity 17 side in accordance with the difference in height of the circuits 3....

[0191] The height of the circuits 3... can be freely selected. In the fifth embodiment, the height of the other circuits 3 is set relatively low compared to the height of the central circuit 3 in the figure.

[0192] The inner surface portion 11b of the second split mold 11 corresponding to the central circuit 3 is set in the same manner as in Fig. 5 of Example 1, and the other inner surface portions 11c of the second split mold 11 are set to protrude further than the central inner surface portion 11b. Therefore, the other inner surface portions 11c of the second split mold 11 are fitted into the third split mold 13. A step is formed between the central inner surface portion 11b and the other inner surface portions 11c between the circuits 3.

[0193] The uneven shape of the inner surface of the second split mold 11 makes it possible to obtain the resin molded circuit body 1 shown in FIG.

[0194] In the resin molded circuit body 1 of FIG. 19, the resin surface 5a around the central circuit 3 has a height corresponding to the height of the circuit surface 3a of the central circuit 3 in the figure, and in the other surrounding circuits 3, the resin surfaces 5a are lowered according to the height of the circuit surfaces 3a of the other circuits 3.

[0195] Therefore, in the fourth embodiment, the resin surface 5a has a stepped shape in the middle between the central circuit 3 and the circuits 3 on both sides.

[0196] By increasing the height of the circuit 3, it is possible to accommodate an increase in the amount of heat generated by the mounted circuit elements and the like.

[0197] The height of the circuits 3... can be freely set, and the corresponding uneven shape on the cavity 17 side of the second split mold 11 can also be changed in various ways according to the setting of the height of the circuits 3....

[0198] In the fourth embodiment as well, the same effects as those in the first embodiment can be achieved. EXAMPLES

[0199] Fig. 20 to Fig. 23 show Example 5. Fig. 20 corresponds to Fig. 5 and is a cross-sectional view of a mold used in a manufacturing method of a resin-molded circuit body. Fig. 21 corresponds to Fig. 1 and is a cross-sectional view of the resin-molded circuit body taken along the line XXI-XXI in Fig. 22. Fig. 22 is a plan view of a resin-molded circuit body having circuits crossing in a bridge shape. Fig. 23 is a back view of a resin-molded circuit body having circuits crossing in a bridge shape.

[0200] In this fifth embodiment, as shown in Fig. 20 to Fig. 23, a pair of front and back circuits 3... are provided with a portion where they partially cross each other in a bridge shape. In both cases, the circuit portions on both sides are connected by a bridge portion 3d.

[0201] The bridge portions 3d of the pair of circuits 3 are disposed facing each other and cross each other so as to straddle each other.

[0202] Both circuits 3 have linear circuit surfaces 3a, 3b on the front and back. Each circuit has island-shaped circuit surfaces 3a, 3b on the front and back on both sides of a bridge portion 3d.

[0203] The circuit surfaces 3a and 3b are exposed from the resin surfaces 5a and 5b of the resin molded portion 5, respectively.

[0204] In this manner, the circuit 3 of the fifth embodiment has a configuration in which at least a part of the front and back circuit surfaces 3a, 3b is exposed from the resin surfaces 5a, 5b of the resin molded portion 5.

[0205] The configuration in which at least a part of the front and rear circuit surfaces 3a, 3b is exposed from the resin surface of the resin molded portion is not limited to the bridge portion, but can also be applied to other circuit configurations.

[0206] 20, the positioning portion of this Example 5 is an adhesive layer 21. The positioning portion of the first split mold 9 is provided with the adhesive layer 21 on one side of the cavity 17 of the first split mold 9, similar to Example 1.

[0207] In the manufacturing method of the resin molded circuit body 1 of this embodiment 5, one circuit 3, including the circuit surface 3a of the bridge portion 3d, is adhered and positioned to the adhesive layer 21, which is the positioning portion of the first split mold 9. The other circuit 3 is positioned and positioned by adhering the circuit surfaces 3b on both sides across the bridge portion 3d.

[0208] The arrangement of both circuits 3 above and below the adhesive layer 21 is arbitrary.

[0209] The flow of resin is the same as in the above embodiment, where the resin is forced into cavity 17 through gate 11a, flows including between bridge portions 3d of circuit 3, and is then cured to obtain the resin molded circuit body 1 of Figures 21 to 23.

[0210] In this embodiment as well, the same effects as those of the above embodiment can be achieved. [Explanation of symbols]

[0211] 1 Resin molded circuit body 1b Joint surface 3 Circuit 3a, 3b circuit side 3c Circumferential side 5 Resin molded part 5a, 5b Resin surface 7. Mold 9 First split mold 11 Second split mold Gate 11a 11b, 11c Inner surface 13 Third split mold 15 Fourth split mold 17 Cavity 19 Transfer Room 21 Adhesive layer (positioning part) 23 Resin 25 Metal substrate (substrate) 27 Insulating layer 29 Metal-based circuit board (circuit board) 33 Positioning pin (positioning part) 35 Counterbore (positioning part) Du Dare

Claims

1. a step of filling a peripheral side surface of the circuit arranged according to the circuit pattern with resin to form a resin molded circuit body; a step of laminating and bonding the resin-molded circuit body, an insulating layer, and a metal substrate, wherein a circuit surface of the circuit constituting a surface of the resin-molded circuit body to be bonded to the insulating layer and a resin surface of the resin are substantially flush with each other; A method for manufacturing a circuit board.

2. the metal substrate has a heat sink shape including a plurality of fins; The method for manufacturing the circuit board according to claim 1 .

3. further comprising the step of mounting a circuit element on the circuit. The method for manufacturing a circuit board according to claim 1 or 2.

4. The thickness of the circuit is 0.5 mm or more. The method for manufacturing a circuit board according to any one of claims 1 to 3.

5. The insulating layer is filled with an inorganic filler at 30 to 85% by volume. The method for manufacturing a circuit board according to any one of claims 1 to 4.

6. The thermal expansion coefficient of the resin and the thermal expansion coefficient of the circuit are adjusted to be approximately the same. The method for manufacturing a circuit board according to any one of claims 1 to 5.

7. The resin comprises a thermosetting resin. The method for manufacturing a circuit board according to any one of claims 1 to 6.

8. The insulating layer contains a resin composed of an epoxy resin and a cyanate resin, either singly or in combination of two or more thereof. The method for manufacturing a circuit board according to any one of claims 1 to 7.

9. the insulating layer contains one or more materials selected from alumina, silica, aluminum nitride, boron nitride, silicon nitride, and magnesium oxide; The method for manufacturing a circuit board according to any one of claims 1 to 8.

10. The insulating layer includes a coupling agent. The method for manufacturing a circuit board according to any one of claims 1 to 9.

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