Method for manufacturing insulated circuit board with heat sink

Abstract

A method for manufacturing an insulated circuit board with a heat sink, the circuit board comprising a heat sink including a flat, plate-shaped top plate portion and a heat-dissipating fin, an insulation layer provided on the top plate portion side of the heat sink, and a circuit layer provided on the insulation layer, the method comprising: a material formation step for fabricating the top plate portion separately from the fin; a first bonding step in which the top plate portion is laminated on one surface side of the insulation layer, and a metal plate for the circuit layer is laminated on the other surface side of the insulation layer, followed by bonding the laminated members together; and a second bonding step in which, after the first bonding step, the fin is bonded to a surface of the top plate portion opposite to the surface bonded to the insulation layer.

Description

Manufacturing method for insulating circuit board with heat sink

[0001] The present invention relates to a method for manufacturing an insulated circuit board with a heat sink, which includes a heat sink with fins for heat dissipation, an insulating layer provided on the top plate side of the heat sink, and a circuit layer provided on this insulating layer.

[0002] This application claims priority based on Japanese Patent Application No. 2024-17710, filed February 8, 2024, the contents of which are incorporated herein by reference.

[0003] 2. Description of the Related Art In order to improve the heat dissipation properties of insulating circuit boards, development has been underway of insulating circuit boards with heat sinks provided on insulating layers.

[0004] The heat sink provided on such an insulated circuit board may have heat dissipation fins on the top plate thereof, and an insulating layer is provided on the top plate of the heat sink with the fins, with a circuit layer provided on the opposite side of the insulating layer from the top plate, thereby forming an insulated circuit board.

[0005] As a method for manufacturing this type of insulating circuit board, for example, a method for manufacturing a power module is disclosed in Patent Document 1. In this manufacturing method, a heat sink integrally formed with heat dissipation fins and a circuit layer are bonded together via an insulating resin layer containing ceramics.

[0006] Patent Document 2 proposes a manufacturing method for a wiring board with a heat sink, in which a separately manufactured top plate portion and heat dissipation fins are sandwiched with solder material and then stacked on a wiring metal plate and an insulating substrate, and the top plate portion of the heat sink and the heat dissipation fins are joined at the same time as the substrates are joined.

[0007] Furthermore, Patent Document 3 discloses a method for manufacturing a heat sink-integrated insulating circuit board in which the gaps between the heat dissipation fins are filled with a water-soluble or organic solvent-soluble polymer, and the heat sink and the insulating resin layer are directly bonded together.

[0008] Japanese Patent Laid-Open No. 11-204700 Japanese Patent Laid-Open No. 2001-298136 Japanese Patent Laid-Open No. 2012-28421

[0009] When using the manufacturing methods described in Patent Documents 1 and 2, an insulating layer is bonded to the top plate of a heat sink with fins. However, because the bonding is performed under high pressure and thermal history, there is a risk of plastic deformation of the peripheral fins. Furthermore, when bonding to the insulating resin layer, the entire fin portion is prone to oxidation and discoloration during heat treatment under atmospheric pressure. Therefore, surface treatment is required, but achieving uniform surface treatment across the complexly formed gaps between the fins is difficult.

[0010] Furthermore, an insulating layer is bonded to the top plate of a heat sink with fins formed on it, but since the fins are formed on the side of the heat sink opposite the side to which the insulating layer is bonded, there is a risk that the fins will tilt or fall over when bonding the heat sink and the insulating layer, and the number of stacking layers will increase, resulting in poor productivity.

[0011] Furthermore, heat sinks typically have areas with fins and areas without, and the height of the fins varies, resulting in uneven pressure when applying pressure to the insulating layer and top plate. This uneven pressure can lead to poor bonding and the formation of voids within the resin that forms the insulating layer. This can lead to, for example, poor bonding at the interface, which can easily lead to delamination when mounting semiconductor elements. Furthermore, in the case of a resin insulating layer, voids within the resin can cause poor dielectric strength.

[0012] In the case of Patent Document 3, an attempt is made to achieve uniform bonding, but since the process of filling the gaps between the polymer fins and the process of removing the polymer are required, the number of steps required to manufacture the insulating circuit board increases, making it more time-consuming and reducing productivity.

[0013] The present invention has been made in view of the above circumstances, and an object of the present invention is to easily manufacture an insulating circuit board with a heat sink that has excellent insulation properties and reliability.

[0014] The method for manufacturing an insulated circuit board with a heatsink of the present invention is a method for manufacturing an insulated circuit board with a heatsink that includes a heatsink having a flat top plate portion and fins for heat dissipation, an insulating layer provided on the top plate portion side of the heatsink, and a circuit layer provided on the insulating layer, and includes the following steps: a material forming step of manufacturing the top plate portion separately from the fins; a first joining step of stacking the top plate portion on one side of the insulating layer and a metal plate for a circuit layer on the other side of the insulating layer and joining them together; and a second joining step of joining the fins to the surface of the top plate portion opposite to the surface joined to the insulating layer after the first joining step.

[0015] The top plate and fins are manufactured separately, and then in the first step, the top plate is laminated on one side of the insulating layer and a metal plate for the circuit layer is laminated on the other side. By joining these together, pressure can be applied uniformly across the entire surface. This prevents uneven pressure at the joint between the insulating layer and the top plate, ensuring a good bond. This makes it possible to provide an insulated circuit board with a heat sink that is excellent in insulation and reliability, and allows semiconductor elements to be mounted stably and with high precision on the circuit layer. Furthermore, the second step, in which the fins are bonded to the top plate at a final stage, improves process fluidity, reduces manufacturing man-hours, and improves workability.

[0016] In the present invention, after the first joining step, the circuit layer metal plate may be subjected to an etching treatment to form the circuit layer.

[0017] Even if the circuit layer has a complex circuit pattern, during the first bonding process, the flat metal plate for the circuit layer, the insulating layer, and the top plate portion are bonded together, so that they can be bonded uniformly over the entire bonding surface. Therefore, the circuit layer after the etching process is also firmly bonded to the insulating layer, and peeling and other problems can be prevented.

[0018] In the present invention, the fins may be formed in a pin or plate shape, which allows these pin or plate fins to be accurately and easily joined to predetermined positions on the top plate, thereby ensuring the surface area and improving the heat dissipation properties of the insulating circuit board.

[0019] Furthermore, in the present invention, the fins may be bonded by any one of diffusion bonding, ultrasonic bonding, and sinter bonding.

[0020] The fins can be easily and reliably bonded to the top plate by diffusion bonding, ultrasonic bonding, or sinter bonding. In any case, the top plate can be uniformly bonded to the entire surface of the insulating layer in the first bonding step, thereby forming a solidly integrated heat sink and providing a high-quality insulating circuit board with excellent insulation properties while suppressing a decrease in breakdown voltage.

[0021] Preferably, the fins have a surface with irregularities, which can further improve heat dissipation.

[0022] The insulating layer may be formed of a thermosetting resin. As described above, the insulating layer can be bonded by applying uniform pressure to the entire surface in the first bonding step, which prevents voids from forming inside the insulating layer and ensures a good bond without unevenness. Furthermore, because the insulating layer is formed of a resin, deformation such as warping is prevented, which enables the stable production of high-quality insulated circuit boards with a low defect rate.

[0023] The thermosetting resin of the insulating layer may be filled with a thermally conductive filler, thereby improving thermal conductivity.

[0024] According to the present invention, the first bonding step bonds the flat metal plate for the circuit layer, the insulating layer, and the top plate portion, so that uniform pressure can be applied to the entire surface to obtain a good bonded state. Even when the insulating layer is made of a thermosetting resin, the occurrence of internal voids can be suppressed, and an extremely good insulated circuit board with a heat sink that has excellent insulation properties and reliability can be easily manufactured.

[0025] FIG. 1 is a perspective view showing an insulating circuit board with a heat sink in the manufacturing method of the present invention. FIG. 2 is a flowchart showing a manufacturing method of an insulating circuit board with a heat sink of the present invention. FIG. 3 is a perspective view showing a state before bonding in the first bonding step. FIG. 4 is a perspective view showing a state after bonding in the first bonding step. FIG. 5 is a perspective view showing a state before bonding in the second bonding step. FIG. 6 is a perspective view showing a state after bonding in the second bonding step. FIG. 7 is a front view showing a diffusion bonding method in the second bonding step. FIG. 8 is a front view showing an ultrasonic bonding method in the second bonding step. FIG. 9 is a front view showing a sinter bonding method in the second bonding step. FIG. 10 is a front view showing a cross section of a top plate portion showing an example in which recesses are formed on the outer peripheral surface of the fins. FIG. 11 is a perspective view showing an embodiment of an insulating circuit board with a heat sink in which the fins are plate-shaped.

[0026] Hereinafter, an embodiment of the method for manufacturing an insulating circuit board with a heat sink according to the present invention will be described with reference to the drawings.

[0027] As shown in FIG. 1, an insulating circuit board 1 with a heat sink manufactured by the manufacturing method of this embodiment includes a heat sink 2, an insulating layer 3, and a circuit layer 4.

[0028] The heat sink 2 is intended to dissipate heat from the insulating layer 3 and circuit layer 4, and includes a flat top plate 10 that serves as a heat sink, and heat dissipation fins 11 that are joined to the top plate 10. The heat sink 2 is made of copper or a copper alloy, aluminum or an aluminum alloy, or the like, which have good thermal conductivity. In this embodiment, the top plate 10 and the fins 11 are both made of copper (oxygen-free copper), and are joined together to form the integrated heat sink 2.

[0029] The top plate portion 10 is formed to a thickness of, for example, 3 mm to 10 mm, and is joined to one surface side (the lower surface side in FIG. 1 ) of the insulating layer 3 .

[0030] On the other hand, the fins 11 are pin-shaped, such as cylindrical or rectangular, or plate-shaped. In this embodiment, the fins 11 are cylindrical pin-shaped, all formed to the same length, and are provided on the underside of the top plate portion 10 (the side opposite to the joint surface with the insulating layer 3).

[0031] The insulating layer 3 is provided to prevent electrical connection between the circuit layer 4 and the heat sink 2, and is made of an insulating material such as an insulating resin or ceramics. In this embodiment, the insulating layer 3 is made of an insulating thermosetting resin.

[0032] In particular, in this embodiment, a thermosetting resin containing a filler is used for the insulating layer 3 to ensure strength and thermal conductivity. Here, the filler may be a thermally conductive filler such as alumina, boron nitride, or aluminum nitride. The thermosetting resin may be an epoxy resin or the like. For example, the insulating layer 3 is made of a resin composition containing alumina as a filler, epoxy resin as a thermosetting resin, and a curing agent. The thickness of the insulating layer 3 is, for example, in the range of 20 μm to 250 μm, and is 60 μm in this embodiment.

[0033] The circuit layer 4 is formed by joining a circuit layer metal plate 12 made of a metal with excellent conductivity to the side of the insulating layer 3 opposite to the joining surface of the top plate portion 10 (the upper surface side in FIG. 1 ). The circuit layer metal plate 12 may be a rolled plate of copper or a copper alloy, aluminum or an aluminum alloy, or the like. In this embodiment, a rolled plate of oxygen-free copper is used as the circuit layer metal plate 12.

[0034] As will be described later, the circuit layer 4 is formed into a predetermined circuit pattern by etching the circuit layer metal plate 12 bonded to the upper surface of the insulating layer 3. The upper surface of the circuit layer 4 serves as a mounting surface on which the semiconductor element 13 is mounted, and the semiconductor element 13 is mounted by solder or the like. Here, the thickness of the circuit layer 4 (circuit layer metal plate 12) is formed to be, for example, 0.3 mm or more and 3 mm or less, and is formed to be 0.5 mm in this embodiment.

[0035] Next, a method for manufacturing the insulating circuit board 1 with a heat sink configured as described above will be described. Fig. 2 shows a flowchart of the method for manufacturing the insulating circuit board with a heat sink of the present invention, which includes a material forming step, a first bonding step, an etching step, and a second bonding step. The steps will be described below in order.

[0036] (Material Forming Process) The top plate portion 10 and fins 11 of the heat sink 2, the insulating layer 3, and the metal plate 12 for the circuit layer are each formed to a predetermined shape and size. The top plate portion 10 and the multiple fins 11 of the heat sink 2 are manufactured separately. In this embodiment, the top plate portion 10, the insulating layer 3, and the metal plate 12 for the circuit layer are formed to the same shape and size.

[0037] It is desirable that the top plate portion 10 and the circuit layer metal plate 12 are each a single flat plate. Furthermore, if the top plate portion 10 is smaller than the insulating layer 3 in plan view from the stacking direction, it is desirable that the circuit layer metal plate 12 be equal to or larger than the size of the top plate portion 10, and it is even more desirable that they be the same size. Alternatively, if the top plate portion 10 is equal to or larger than the insulating layer 3, it is desirable that the circuit layer metal plate 12 is equal to or larger than the insulating layer 3. In other words, it is desirable that the size of the joint surface between the top plate portion 10 and the insulating layer 3 is the same as the size of the joint surface between the circuit layer metal plate 12 and the insulating layer 3, and it is desirable that the positions of the joint surfaces when viewed from the stacking direction overlap when stacked.

[0038] The fins 11 are all cylindrical with the same length and diameter, and an appropriate number are produced depending on the area of ​​the joining surface of the top plate 10, the installation spacing, etc., taking heat dissipation efficiency into consideration. For example, the cylindrical fins are formed with a diameter of 0.5 mm to 6.0 mm and a length of 1.0 mm to 10 mm, and the spacing between the fins 11 is 0.5 mm to 4.0 mm. In this embodiment, the diameter and length of the fins 11 are 2 mm and 6 mm, respectively, and the spacing between the fins 11 is 1 mm.

[0039] The insulating layer 3 is made of a sheet of a resin composition containing alumina, epoxy resin, and a curing agent. The metal plate 12 for circuit layers is formed by punching out a rolled plate.

[0040] (First bonding step) A top plate portion 10 is disposed on one side (the bottom side in FIG. 3A ) of the insulating layer 3 (the sheet of resin composition), and a metal plate 12 for a circuit layer is disposed on the other side (the top side in FIG. 3A ) of the insulating layer 3, and these are stacked together.

[0041] As a result, as shown in FIG. 3B, the top plate portion 10, the insulating layer 3 (a sheet of a resin composition), and the metal plate 12 for the circuit layer are laminated in this order.

[0042] This laminate of the top plate portion 10, insulating layer 3, and metal plate 12 for the circuit layer is pressurized and heated in the stacking direction to harden the insulating layer 3 (an insulating sheet made of a resin composition), and the top plate portion 10 and the insulating layer 3, and the insulating layer 3 and the metal plate 12 for the circuit layer are bonded together by thermocompression.

[0043] The conditions for compression bonding are preferably a heating temperature in the range of 150°C to 200°C, a holding time at this heating temperature in the range of 30 minutes to 90 minutes, and a pressure in the lamination direction in the range of 50 MPa to 200 MPa.

[0044] When the insulating layer 3 is made of ceramics, the ceramics can be bonded by applying a predetermined brazing filler metal between the circuit layer metal plate 12 and the top plate portion 10 and then pressurizing and heating them. When the circuit layer metal plate 12 and the top plate portion 10 are made of copper or a copper alloy, a brazing filler metal such as Ag-Cu-Ti is used as the brazing filler metal.

[0045] (Etching process) After the first bonding process, the circuit layer metal plate 12 bonded to the upper surface of the insulating layer 3 is subjected to an etching process to form the circuit layer 4. In this case, a resist layer corresponding to the circuit pattern is formed on the circuit layer metal plate 12, and by immersing the metal plate 12 in this state in an etching solution, the portions not covered by the resist layer are removed, and the circuit layer 4 having the predetermined circuit pattern is formed.

[0046] 4A and 4B , in the second joining step, the fins 11 are joined to the surface of the top plate portion 10 opposite to the surface joined to the insulating layer 3. This results in the formation of the heat sink 2 in which the top plate portion 10 and the fins 11 are integrated.

[0047] The fins 11 may be bonded by any of diffusion bonding, ultrasonic bonding, and sinter bonding. In this embodiment, a case where cylindrical fins 11 are bonded will be described, but the same bonding method can also be used when bonding fins other than cylindrical fins such as prismatic fins or plate-like fins.

[0048] FIG. 5A shows a case where the fins 11 are bonded to the top plate portion 10 by diffusion bonding.

[0049] In diffusion bonding, the bonding surfaces (end faces) of each fin 11 are brought into close contact with the top plate 10, and pressure is applied to minimize plastic deformation at a temperature below the melting point of the copper (oxygen-free copper) that makes up the fins 11 and top plate 10, utilizing the atomic diffusion that occurs between the bonding surfaces. In this way, the fins 11 are integrated with the top plate 10 to form the heat sink 2.

[0050] 5B shows a case where the fin 11 is joined to the top plate 10 by ultrasonic bonding. For ultrasonic bonding, an ultrasonic bonding machine (not shown) equipped with an ultrasonic oscillator, an ultrasonic vibrator, and a horn is used. High-frequency current generated by the ultrasonic oscillator of the ultrasonic bonding machine is supplied to the ultrasonic vibrator as electrical energy, and then transmitted from the ultrasonic vibrator to the horn as ultrasonic energy, which then ultrasonically vibrates the horn. By applying ultrasonic vibrations to the fin 11 and the top plate 10 through the fin 11 abutting the horn, oxide films and deposits present at the bonding interface are destroyed and dispersed. The fin 11 and the top plate 10 are pressed together while undergoing plastic deformation in this state, and atomic forces act to bond them together.

[0051] FIG. 5C shows a case where the fins 11 are joined to the top plate portion 10 by sinter bonding.

[0052] In the sinter bonding, bonding is performed using a bonding paste 17 containing copper particles, a solvent, and an additive. After being applied to the top plate portion 10, the bonding paste 17 is preheated at a temperature of 50°C to 150°C for 1 minute to 30 minutes to volatilize the solvent contained in the bonding paste 17.

[0053] The tip surface of the fin 11 is placed in contact with the top plate 10 on which the bonding paste 17 has been applied and dried, and the fin 11 is then heated, for example, in a non-reducing atmosphere at a temperature of 200°C to 300°C for approximately 1 minute to 10 minutes while applying a pressure of 0.5 MPa to 10 MPa. The non-reducing atmosphere refers to a state in which the fin 11 is filled with a non-reducing gas, such as a rare gas such as nitrogen or argon. By performing sintering bonding under the above conditions, the copper particles are sintered to bond the fin 11 and the top plate 10.

[0054] According to the manufacturing method of the insulated circuit board 1 with a heat sink in the above embodiment of the present invention, the flat top plate portion 10 is manufactured separately from the fins 11, and in the first joining step, the insulating layer 3, the top plate portion 10, and the metal plate 12 for the circuit layer are stacked and joined together, so that uniform pressure can be applied between the top plate portion 10 and the insulating layer 3 in the surface direction to reliably join them together.

[0055] Then, after an etching step, in a second bonding step, the fins 11 are bonded to the top plate 10 by diffusion bonding, ultrasonic bonding, or sinter bonding. In any case, the top plate 10 can be uniformly bonded to the entire surface of one surface of the insulating layer 3 (the lower surface in FIG. 3A ) in the first bonding step, so that a firmly integrated heat sink 2 can be formed, and a reduction in breakdown voltage can be suppressed, making it possible to provide a high-quality insulating circuit board with a heat sink 1 that has excellent insulation properties.

[0056] Furthermore, even if it becomes necessary to re-bond the fins 11 due to a defect, the fins 11 can be detached from the top plate 10 by applying a shear force to the fins 11, allowing new fins 11 to be re-fixed, and repairability is also good. In this case, ultrasonic bonding and sinter bonding are more likely to cause the fins 11 to detach by shear than diffusion bonding, and are therefore superior in repairability.

[0057] In the above embodiment, the fins 11 are formed on the outer peripheral surface of a cylindrical or prismatic column, but they may also be formed with projections and recesses. The fin 15 shown in FIG. 6 shows an example in which a large number of dimple-shaped recesses 15a are formed on the outer peripheral surface. This increases the surface area of ​​the fin 15 compared to a cylindrical outer peripheral surface, thereby improving heat dissipation. Instead of the recesses 15a, projections may be formed.

[0058] Although pin-shaped fins have been shown as an example of a heat sink, plate-shaped (plate-like) fins are also possible. FIG. 7 shows an example of a heat sink 20 having plate-shaped fins 21. The fins 21 are arranged parallel to one another so that a refrigerant can flow between them. In this case, the fins are formed in a flat plate shape, but they may also be formed in a corrugated plate shape. Furthermore, recesses and protrusions may be formed on the surface of the fins as shown in FIG. 6. These recesses and protrusions together are referred to as uneven portions.

[0059] The following describes the results of tests evaluating the performance of the heat sink-equipped insulating circuit board 1 manufactured by the manufacturing method of the present invention. The tests included a bondability test and an insulation test.

[0060] The heat sink and the metal plate for the circuit layer were made of oxygen-free copper, and the insulating layer was made of a resin composition formed into a sheet shape containing alumina as a filler, epoxy resin as a thermosetting resin, and a curing agent, all of which were formed to the same plane area.

[0061] The top plate portion of the heat sink, the insulating layer, and the metal plate for the circuit layer were bonded at a heating temperature of 180° C. for 60 minutes under a pressure of 100 MPa.

[0062] After bonding the top plate portion, insulating layer, and metal plate for circuit layer, fins were bonded to the top plate portion by the method shown in Table 1.

[0063] As a comparative example, a finned heat sink in which fins were previously formed integrally by forging was used, and this finned heat sink was joined to an insulating layer and a circuit layer.

[0064] (Bondability test) The bonding state between the circuit layer 4 and the insulating layer 3 was observed using an ultrasonic flaw detector (FineSAT200 manufactured by Hitachi Power Solutions Co., Ltd.), and the incidence of voids was measured. Since voids are shown as white areas in the ultrasonic flaw detector image, those in which the area of ​​the white areas was less than 5% of the bonding area were rated as "good" (passed), and those in which the area was 5% or more were rated as "poor."

[0065] (Insulation Test) A partial discharge tester manufactured by Mitsubishi Electric Wire Co., Ltd. was used as a measuring device, and electrodes were placed in contact with the surface of the circuit layer 4 and the surface (underside) of the top plate portion 10, and an AC voltage was applied between the two electrodes to measure the breakdown voltage. The voltage was increased in steps of 0 kV to 0.5 kV (holding time 30 seconds), and the voltage at which breakdown occurred (the voltage at which the leakage voltage became 10 mA or more) was defined as the breakdown voltage.

[0066] The evaluation criteria for the insulation test were as follows: if the proportion of samples with a breakdown voltage of less than 4 kV among all the samples was less than 10%, it was rated as "good" (passed); if it was 10% or more, it was rated as "bad."

[0067] The evaluation results of the above tests are shown in Table 1.

[0068]

[0069] In the comparative example, when the finned heat sink and the circuit layer were bonded via an insulating layer, both the bondability and the insulation were judged to be "poor" (failed).

[0070] On the other hand, when the top plate portion 10, the insulating layer 3, and the metal plate 12 for the circuit layer were stacked and bonded separately from the fins 11 as in the examples, both the bondability and the insulation were judged to be "good" (passed) regardless of whether the bonding with the fins 11 was by diffusion bonding (Example 1), ultrasonic bonding (Example 2), or sinter bonding (Example 3).

[0071] From the above test results, it was confirmed that the manufacturing method of the present invention provides good bonding between the circuit layer 4 and the top plate portion 10 of the heat sink 2 and the insulating layer 3, minimizes the occurrence of voids, and provides excellent insulation, making it possible to manufacture an insulated circuit board 1 with a heat sink of stable quality.

[0072] The present invention is not limited to the configurations of the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0073] The present invention does not preclude bonding a metal plate for a circuit layer that has been formed into a circuit pattern in advance onto the insulating layer 3. This method is also possible when the circuit pattern is not complicated or when there is no significant difference in area with the insulating layer 3, and a metal plate for a circuit layer that has been punched into the shape of the circuit pattern by press working is used.

[0074] Furthermore, the joining of the fins 11 to the top plate portion 10 is not limited to the above three types of joining, and brazing material or adhesive may also be used.

[0075] According to the present invention, an insulating circuit board with a heat sink having excellent insulation properties and reliability can be used, for example, as an insulating circuit board with a heat sink for a power module.

[0076] REFERENCE SIGNS LIST 1 Insulated circuit board with heat sink 2, 20 Heat sink 3 Insulating layer (insulating sheet) 4 Circuit layer 10 Top plate portion 11, 15, 21 Fin 15a Recess 12 Metal plate for circuit layer 17 Bonding paste

Claims

1. A method for manufacturing an insulated circuit board with a heatsink, the method comprising: a heatsink with a flat top plate and fins for heat dissipation; an insulating layer provided on the top plate side of the heatsink; and a circuit layer provided on the insulating layer, the method comprising: a material forming step of manufacturing the top plate separately from the fins; a first joining step of laminating the top plate on one side of the insulating layer and a metal plate for a circuit layer on the other side of the insulating layer and joining them together; and a second joining step of joining the fins to the surface of the top plate opposite to the surface joined to the insulating layer after the first joining step.

2. The method for manufacturing an insulating circuit board with a heat sink according to claim 1, wherein after the first bonding step, the metal plate for the circuit layer is subjected to an etching process to form the circuit layer.

3. The method for manufacturing an insulating circuit board with a heat sink according to claim 1, wherein the fins are formed in the shape of pins or plates.

4. The method for manufacturing an insulating circuit board with a heat sink according to claim 2, wherein the fins are formed in the shape of pins or plates.

5. The method for manufacturing an insulating circuit board with a heat sink according to claim 3, wherein the fins are bonded to the top plate by any one of diffusion bonding, ultrasonic bonding, and sinter bonding.

6. The method for manufacturing an insulating circuit board with a heat sink according to claim 4, wherein the fins are bonded to the top plate by any one of diffusion bonding, ultrasonic bonding, and sinter bonding.

7. The method for manufacturing an insulating circuit board with a heat sink according to claim 1, wherein the insulating layer is formed from a thermosetting resin.

8. The method for manufacturing an insulating circuit board with a heat sink according to claim 2, wherein the insulating layer is formed from a thermosetting resin.

9. The method for manufacturing an insulating circuit board with a heat sink according to claim 7, wherein the thermosetting resin of the insulating layer is filled with a thermally conductive filler.

10. The method for manufacturing an insulating circuit board with a heat sink according to claim 8, wherein the thermosetting resin of the insulating layer is filled with a thermally conductive filler.

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