Insulated metal substrate and method of manufacturing the same

Abstract

An insulating metal substrate and a manufacturing method thereof are disclosed. The insulating metal substrate includes a circuit pattern layer, a packaging layer, a first adhesive layer, a second adhesive layer, and a heat dissipation element. The packaging layer fills gaps between metal circuits of the circuit pattern layer, and an upper surface of the packaging layer is flush with an upper surface of the circuit pattern layer. The first adhesive layer and the second adhesive layer are disposed between the circuit pattern layer and the heat dissipation element, and an adhesive force between the first adhesive layer and the second adhesive layer is greater than 80 kg / cm 2 .

Description

Technical Field

[0001] This invention relates to an insulating metal substrate, and more particularly to an insulating metal substrate suitable for use in high-power applications. Background Technology

[0002] Generally, a heat sink can be an insulated metal substrate (IMS) or a direct-bonded copper (DBC) ceramic substrate. Electronic components, such as IC chips, are typically bonded to the heat sink, establishing an electrical connection between the two. These components generate heat during operation, which gradually accumulates on the components. Heat can be dissipated to the external environment above via the metal wiring patterns on the surface of the heat sink, or from the bottom of the electronic components through the heat sink to the external environment below. In other words, the heat sink acts as a heat conduction medium.

[0003] Although DBC ceramic substrates can withstand temperatures up to 1000°C, ceramic materials are hard yet brittle. During the manufacturing process, DBC ceramic substrates are difficult to machine, such as through drilling and cutting. Furthermore, due to the significant difference in thermal expansion coefficients between the copper foil and the ceramic layer, delamination can easily occur between the copper foil and the ceramic layer under high-temperature conditions, especially in copper applications with thicknesses ranging from 0.3mm to 10mm.

[0004] IMS (Insulated Metal Membrane) uses a high-molecular polymer as the main material for the thermally conductive insulating layer, which is also mixed with a large amount of thermally conductive filler. A metal foil is placed on the upper and lower surfaces of the thermally conductive insulating layer to form a sandwich-structured heat dissipation substrate. Compared with ceramic materials, high-molecular polymers are much easier to machine, and there is also better adhesion between the thermally conductive insulating layer and the metal foil.

[0005] Currently, in high-power applications such as electric vehicles, the Internet of Things (IoT), and high-speed computing, the output power of electronic components has increased significantly compared to the past, making thermal management of heat dissipation substrates a hot topic. This necessitates the use of thicker copper foil in heat dissipation substrates, allowing heat to be conducted both horizontally and vertically along the copper foil layer and further dissipated to the external environment, achieving effective heat dissipation. However, DBC ceramic substrates suffer from delamination at high temperatures and are difficult to machine. IMS (Insulated Metal Melting) is more suitable for high-power applications requiring thick copper foil.

[0006] US Patent Application Publication US2020 / 0229303A1 discloses a method for manufacturing an insulating metal substrate (IMS) with a polymer insulating layer. This method involves first forming multiple conductive metal sheets, then placing these sheets onto an insulating layer on a metal substrate, where the metal substrate serves as the heat sink fins. The substrate is then pressed together in a hot press to form the insulating metal substrate. However, this method suffers from misalignment, as the conductive metal sheets cannot be precisely positioned on the insulating layer. Furthermore, to increase the heat dissipation area and facilitate high-power applications, the heat sink fins have protrusions, meaning they are not uniformly thick metal plates. With this heat dissipation design, the hot press cannot apply pressure evenly across the entire surface of the heat sink fins during hot pressing, resulting in poor adhesion between the layers in the hot-pressed insulating metal substrate. In particular, the insulating metal substrate is prone to separation or peeling when operating in high-temperature and high-humidity environments.

[0007] Clearly, the traditional manufacturing methods for insulating metal substrates (IMS) urgently need further improvement. Summary of the Invention

[0008] To address the aforementioned problems, this invention discloses an insulating metal substrate and its manufacturing method. The layers in this insulating metal substrate do not separate, thus avoiding alignment errors. The insulating metal substrate of this invention exhibits good thermal conductivity and a high glass transition temperature (Tg), making it suitable for high-power applications requiring thick copper layers.

[0009] According to a first aspect of the present invention, an insulating metal substrate is disclosed, comprising: a circuit pattern layer; an encapsulation layer, the encapsulation layer filling the gaps between metal circuits in the circuit pattern layer, and the upper surface of the encapsulation layer being flush with the upper surface of the circuit pattern layer; a first adhesive layer; a second adhesive layer; and a heat dissipation element located below the circuit pattern layer and the encapsulation layer; wherein the first adhesive layer and the second adhesive layer are disposed between the circuit pattern layer and the heat dissipation element, the first adhesive layer contacting the circuit pattern layer and the encapsulation layer, and the second adhesive layer contacting the heat dissipation element, wherein the first adhesive layer and the second adhesive layer form physical contact and have an adhesion force greater than 80 kg / cm². 2 .

[0010] In one embodiment, the circuit pattern layer comprises copper and has a thickness of 0.3 mm to 10 mm.

[0011] In one embodiment, the adhesion between the first adhesive layer and the circuit pattern layer is greater than 80 kg / cm². 2 The adhesion between the second adhesive layer and the heat dissipation element is greater than 80 kg / cm². 2.

[0012] In one embodiment, the glass transfer temperature Tg of the first adhesive layer and the second adhesive layer is greater than 150°C.

[0013] In one embodiment, the thickness of each of the first adhesive layer and the second adhesive layer is in the range of 25 μm to 100 μm, and the adhesion between the first adhesive layer and the second adhesive layer is 80 kg / cm². 2 ~300kg / cm 2 Within the range.

[0014] In one embodiment, the first adhesive layer and the second adhesive layer have the same or different compositions.

[0015] In one embodiment, both the first and second adhesive layers are made of an adhesive material comprising a polymer, a thermally conductive filler, a curing agent, and a curing accelerator. The polymer comprises between 15% and 60% by volume of the adhesive material and includes a thermosetting epoxy resin and a modified polymer that improves the impact resistance of the thermosetting epoxy resin. The modified polymer comprises thermoplastics, rubbers, or combinations thereof, and comprises between 4% and 45% by volume of the polymer. The thermally conductive filler is uniformly dispersed in the polymer and comprises between 40% and 85% by volume of the adhesive material. The curing agent is used to cure the thermosetting epoxy resin at a temperature above 120°C. The curing accelerator comprises urea or a compound thereof. The thermal conductivity of the adhesive material is greater than 3 W / mK.

[0016] In one embodiment, when the adhesive material is made into a sheet material with a thickness of 100 μm, the thermal resistivity of the adhesive material is less than 0.5 °C / W and it can withstand a voltage greater than 500 volts.

[0017] In one embodiment, the thermally conductive filler comprises nitrides, oxides, or mixtures thereof, and may be selected from zirconium nitride, boron nitride, aluminum nitride, silicon nitride, aluminum oxide, magnesium oxide, zinc oxide, silicon dioxide, titanium dioxide, or mixtures thereof.

[0018] In one embodiment, the heat dissipation element includes a base plate and a plurality of protrusions that protrude outward in a direction perpendicular to the extension direction of the base plate, and the protrusions have gaps between them.

[0019] According to a second aspect of the present invention, a method for manufacturing an insulating metal substrate is disclosed, comprising: providing a thermally conductive substrate, the thermally conductive substrate comprising, from bottom to top, a metal substrate, a first adhesive layer and a metal layer; removing a portion of the metal layer to form a circuit pattern layer, the circuit pattern layer exposing a portion of the first adhesive layer; forming an encapsulation layer on the circuit pattern layer; removing a top portion of the encapsulation layer such that the upper surface of the encapsulation layer is flush with the upper surface of the circuit pattern layer; removing the metal substrate; providing a heat dissipation element, wherein a second adhesive layer is disposed on the heat dissipation element; and attaching the second adhesive layer to the first adhesive layer such that the first adhesive layer and the second adhesive layer form physical contact and the adhesion force is greater than 80 kg / cm². 2 .

[0020] In one embodiment, the circuit metal layer comprises copper and has a thickness of 0.3 mm to 10 mm.

[0021] In one embodiment, CNC milling technology is used to remove a portion of the metal layer.

[0022] In one embodiment, the encapsulation layer is formed by potting, screen printing, spraying, or injection molding, and the encapsulation layer comprises an insulating material selected from epoxy molding compound, solder resist, thermally conductive ink, epoxy resin, polyetheretherketone, or polyethersulfone.

[0023] In one embodiment, the heat dissipation element includes a base plate and a plurality of protrusions that protrude outward in a direction perpendicular to the extending direction of the base plate, and there are gaps between the protrusions.

[0024] In one embodiment, the glass transfer temperature Tg of the first adhesive layer and the second adhesive layer is greater than 150°C.

[0025] In one embodiment, after bonding, the adhesion between the first adhesive layer and the circuit pattern layer is greater than 80 kg / cm². 2 The adhesion between the second adhesive layer and the heat dissipation element is greater than 80 kg / cm². 2 .

[0026] In one embodiment, the thickness of each of the first adhesive layer and the second adhesive layer is in the range of 25 μm to 100 μm, and the adhesion between the first adhesive layer and the second adhesive layer is 80 kg / cm². 2 ~300kg / cm 2 Within the range.

[0027] In one embodiment, a reverse fixture is placed on the heat dissipation element and thermoforming is performed to attach the second adhesive layer to the first adhesive layer.

[0028] In one embodiment, the first adhesive layer and the second adhesive layer have the same or different compositions.

[0029] In one embodiment, both the first and second adhesive layers are made of an adhesive material comprising a polymer, a thermally conductive filler, a curing agent, and a curing accelerator. The polymer comprises between 15% and 60% by volume of the adhesive material and includes a thermosetting epoxy resin and a modified polymer that improves the impact resistance of the thermosetting epoxy resin. The modified polymer comprises thermoplastics, rubbers, or combinations thereof, and comprises between 4% and 45% by volume of the polymer. The thermally conductive filler is uniformly dispersed in the polymer and comprises between 40% and 85% by volume of the adhesive material. The curing agent is used to cure the thermosetting epoxy resin at a temperature above 120°C. The curing accelerator comprises urea or a compound thereof. The thermal conductivity of the adhesive material is greater than 3 W / mK.

[0030] In one embodiment, when the adhesive material is made into a sheet material with a thickness of 100 μm, the thermal resistivity of the adhesive material is less than 0.5 °C / W and it can withstand a voltage greater than 500 volts.

[0031] This invention provides an insulating metal substrate and its manufacturing method. This invention avoids the problem of alignment errors and prevents delamination. Furthermore, the insulating metal substrate has good thermal conductivity and a high glass transition temperature (Tg). Therefore, this invention is particularly suitable for high-power applications, providing an effective solution to the problems faced by traditional heat dissipation substrates. Attached Figure Description

[0032] Figure 1 A flowchart showing a method for manufacturing an insulating metal substrate according to an embodiment of the present invention is shown.

[0033] Figures 2A to 2G show Figure 1 The manufacturing method of the insulating metal substrate is shown in the structural cross-sectional view at each stage.

[0034] Figure 3 This diagram shows a cross-sectional view of an insulating metal substrate according to an embodiment of the present invention.

[0035] Figure 4 This diagram illustrates hot pressing according to an embodiment of the present invention.

[0036] The reference numerals in the attached figures are explained as follows:

[0037] Steps S1 to S7

[0038] 11 Metal substrate

[0039] 12 First adhesive layer

[0040] 13 Metal Layers

[0041] 14. Circuit pattern layer

[0042] 141 gap

[0043] 142 Metal Circuit

[0044] 15. Encapsulation layer

[0045] 20 Heat dissipation components

[0046] 21 Base Plate

[0047] 22. Protrusion

[0048] 31 Second adhesive layer

[0049] 100 thermally conductive substrate

[0050] 300 Insulating Metal Substrate

[0051] 500 methods

[0052] C cutting line Detailed Implementation

[0053] To make the above and other technical contents, features and advantages of the present invention more apparent and understandable, relevant embodiments are provided below, and detailed descriptions are given in conjunction with the accompanying drawings.

[0054] Figure 1 A flowchart illustrating a method for manufacturing an insulating metal substrate according to an embodiment of the present invention is shown. The manufacturing method includes the following steps: In step S1, a thermally conductive substrate is provided, the thermally conductive substrate comprising, from bottom to top, a metal substrate, a first adhesive layer, and a metal layer. In step S2, a portion of the metal layer is removed to form a circuit pattern layer, the circuit pattern layer exposing a portion of the first adhesive layer. In step S3, an encapsulation layer is formed on the circuit pattern layer, the encapsulation layer filling the gaps between the metal lines of the circuit pattern layer. In step S4, a top portion of the encapsulation layer is removed, such that the upper surface of the encapsulation layer is flush with the upper surface of the circuit pattern layer. In step S5, the metal substrate is removed. In step S6, a heat dissipation element is provided, wherein a second adhesive layer is disposed on the heat dissipation element. In step S7, the second adhesive layer is bonded to the first adhesive layer, such that physical contact is formed between the first adhesive layer and the second adhesive layer and the adhesion force is greater than 80 kg / cm². 2 .

[0055] The adhesive material used to form the bonding layer is formulated to have a thermal conductivity greater than 3 W / mK, and when made into a sheet material with a thickness of 100 μm, its thermal resistivity is less than 0.5 °C / W. The adhesive material can also withstand voltages greater than 500 volts. Furthermore, the adhesion between the adhesive layer and the metal material is greater than 80 kg / cm². 2 Furthermore, the adhesion between the two adhesive layers is greater than 80 kg / cm². 2 The glass transition temperature (Tg) of the adhesive layer is greater than 150°C. Therefore, this invention is particularly suitable for high-power applications. This invention also utilizes CNC milling technology to remove portions of the metal layer, avoiding alignment errors and improving product yield. The manufacturing method of this insulating metal substrate is described in detail below.

[0056] Please see Figures 2A to 2G Its display Figure 1 The manufacturing method of the insulating metal substrate includes structural cross-sectional views at each stage. Also, refer to... Figure 1 The production process. For example... Figure 2A As shown, in step S1, a thermally conductive substrate 100 is provided, which sequentially comprises a metal substrate 11, a first adhesive layer 12, and a metal layer 13 from bottom to top. In one embodiment, the thermally conductive substrate 100 is generally flat, wherein the first adhesive layer 12 is located between the metal substrate 11 and the metal layer 13, and the lower and upper sides of the first adhesive layer 12 contact the metal substrate 11 and the metal layer 13, respectively. In one embodiment, the metal layer 13 may comprise copper, and the metal substrate 11 may comprise copper or aluminum. In other embodiments, the metal layer 13 and the metal substrate 11 may comprise other metals. The first adhesive layer 12 comprises a polymer and a thermally conductive filler dispersed in the polymer, and is particularly suitable for bonding applications with metal materials, wherein the metal material may be copper, aluminum, nickel, iron, tin, gold, silver, or alloys thereof. The metal substrate 11, the first adhesive layer 12, and the metal layer 13 can be hot-pressed to form a sandwich structure, and after pressing and curing, the adhesion between the first adhesive layer 12 and the metal layer 13 is greater than 80 kg / cm². 2 Even greater than 100 kg / cm 2 Or 120kg / cm 2For use in high-power applications, the metal layer 13 must be sufficiently thick to provide good heat dissipation. Heat generated by electronic components can be dissipated to the external environment through the metal layer 13. In one embodiment, the metal layer 13 is made of copper and has a thickness of 0.3 mm to 10 mm, such as 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, or 9 mm. The metal substrate 11 serves as the substrate during the hot-pressing process and is removed after hot-pressing; therefore, it does not need to be too thick. In one embodiment, the metal substrate 11 is made of copper and has a thickness of 35 μm to 300 μm, such as 70 μm, 105 μm, 140 μm, 175 μm, 210 μm, 245 μm, or 270 μm.

[0057] like Figure 2B As shown, in step S2, a portion of the metal layer 13 is removed to form a circuit pattern layer 14, which exposes a portion of the first adhesive layer 12. The metal layer 13 can be removed mechanically or by wet etching. For example, Computer Numerical Control (CNC) milling technology can be used to remove a portion of the metal layer 13 using a rotary cutter, leaving metal lines 142 on the first adhesive layer 12. The metal lines 142 may include metal pads (not shown) for establishing electrical connections with electronic components (not shown) in subsequent processes. In other words, after removing a portion of the metal layer 13, gaps 141 are created between adjacent metal lines 142, exposing a portion of the first adhesive layer 12. The metal lines 142 may include metal pads for establishing electrical connections with electronic components. Because the metal lines 142 are formed using CNC milling technology, the position of the lines to be formed can be precisely controlled according to product requirements. Compared to the traditional method of first forming a conductive metal sheet and then placing it on an insulating layer, this invention avoids the problem of positional alignment errors. Generally, CNC milling machines generate metal shavings on the circuit pattern layer 14, so after forming the circuit pattern layer 14, wet etching technology can be used to remove residual metal shavings from the surface of the circuit pattern layer 14.

[0058] like Figure 2CAs shown, in step S3, an encapsulation layer 15 is formed on the circuit pattern layer 14, filling the gaps 141 between the metal lines 142 of the circuit pattern layer 14. The encapsulation layer 15 is used to prevent the insulating metal substrate from being infiltrated by water or oxygen, leading to electrical degradation. Generally, the encapsulation layer 15 contains insulating material and can be formed by methods such as potting, screen printing, spraying, or injection molding. For example, in one embodiment, epoxy molding compound (EMC) can be potted into a mold cavity to form the encapsulation layer 15. In another embodiment, solder mask can be printed onto the circuit pattern layer 14 using screen printing to form the encapsulation layer 15. In yet another embodiment, thermally conductive ink can be sprayed onto the circuit pattern layer 14 to form the encapsulation layer 15. In another embodiment, an encapsulation layer 15 can be formed by injection molding an insulating material such as epoxy resin, polyetheretherketone (PEEK), or polyethersulfone (PES) onto the circuit pattern layer 14. However, the material of the encapsulation layer 15 and the method of forming the encapsulation layer 15 are not limited thereto. Typically, the encapsulation layer 15 formed thereby has a thickness greater than the circuit pattern layer 14, covering the entire circuit pattern layer 14 and filling the gaps 141 between the metal lines 142.

[0059] like Figure 2D As shown, in step S4, the top portion of the encapsulation layer 15 is removed so that the upper surface of the encapsulation layer 15 is flush with the upper surface of the circuit pattern layer 14. Because the thickness of the encapsulation layer 15 is greater than the thickness of the circuit pattern layer 14, it is necessary to remove the top portion of the encapsulation layer 15. Preferably, a mechanical method such as grinding can be used to perform the grinding.

[0060] like Figure 2E As shown, in step S5, the metal substrate 11 is removed. As previously mentioned, the metal substrate 11 serves as the substrate in the hot-pressing process, and therefore can be removed after the hot-pressing process is completed. In one embodiment, wet etching, dry etching, or chemical mechanical polishing (CMP) can be used to remove the metal substrate 11.

[0061] like Figure 2FAs shown, in step S6, a heat dissipation element 20 is provided, wherein a second adhesive layer 31 is disposed on the heat dissipation element 20. The heat dissipation element 20 is used to dissipate heat from electronic components to the external environment. The material of the heat dissipation element 20 is not particularly limited, and it can generally be made of metal, such as aluminum, copper, nickel, iron, tin, gold, silver or their alloys, etc. Graphite carbon materials or composite components made of carbon materials can also be used. To meet high-power applications, the heat dissipation element 20 must increase its heat dissipation area to improve heat dissipation efficiency. Therefore, the heat dissipation element 20 typically includes a base plate 21 and a plurality of protrusions 22, which protrude outward in a direction perpendicular to the extension direction of the base plate 21. The protrusions 22 can be cylinders, elliptical cylinders, polygonal prisms, truncated cones, or flat plates, and there are gaps between the protrusions 22 to allow air to flow between them, thereby dissipating heat. In this embodiment, the protrusion 22 is a rectangular flat plate, which are parallel to each other and maintain a consistent spacing. In other embodiments, the heat dissipation element 20 may also include only a base plate 21, i.e., without the protrusion 22. In this case, the base plate 21 has a greater thickness, which facilitates heat conduction along both the horizontal and vertical directions of the base plate 21 and further dissipation to the external environment, thereby achieving an effective heat dissipation effect.

[0062] The second adhesive layer 31 may have the same composition as the first adhesive layer 12, that is, the same components and the same volume percentage of the components. Alternatively, the second adhesive layer 31 may have a different composition than the first adhesive layer 12, that is, different components or different volume percentages of the components. However, both the first adhesive layer 12 and the second adhesive layer 31 contain a polymer and a thermally conductive filler dispersed in the polymer, and are very suitable for bonding applications with metallic materials. Therefore, even if the compositions are different, the compositions of the first adhesive layer 12 and the second adhesive layer 31 are very similar, and their adhesive properties, thermal conductivity, and insulation properties are also similar, as further detailed below.

[0063] like Figure 2G As shown, in step S7, the second adhesive layer 31 is adhered to the first adhesive layer 12, such that the first adhesive layer 12 and the second adhesive layer 31 form physical contact and the adhesion force is greater than 80 kg / cm². 2 This step can be achieved through hot pressing. During hot pressing, the circuit pattern layer 14 and the encapsulation layer 15 are located at the bottom of the pressing space of the hot press, and the heat dissipation element 20 is placed on the surface of the first adhesive layer 12, such as... Figure 2GAs shown, the second adhesive layer 31 contacts the first adhesive layer 12, thus forming an interface between the first adhesive layer 12 and the second adhesive layer 31 after hot pressing. After hot pressing, the second adhesive layer 31 and the heat dissipation element 20 are bonded to each other, and the adhesion between them is greater than 80 kg / cm². 2 Even greater than 100 kg / cm 2 Or 120kg / cm 2 Furthermore, after hot pressing, the second adhesive layer 31 and the first adhesive layer 12 also bond to each other. However, because the second adhesive layer 31 and the first adhesive layer 12 have the same or similar composition, hot pressing makes the second adhesive layer 31 and the first adhesive layer 12 bonded together very tightly. This excellent adhesion is much stronger than the adhesion between an adhesive layer and a metal material. According to the inventors' experiments, the adhesion between the first adhesive layer 12 and the second adhesive layer 31 is greater than 80 kg / cm². 2 For example, at 80 kg / cm 2 ~300kg / cm 2 Within the range, especially 100 kg / cm 2 150kg / cm 2 200kg / cm 2 Or 250kg / cm 2 Therefore, even though the heat dissipation element 20 has a protrusion 22, it prevents the hot press from applying pressure evenly to the topmost surface of the heat dissipation element 20 during the hot pressing process. Figure 2G The top surface shown has good adhesion to prevent the heat dissipation element 20 from separating.

[0064] The first adhesive layer 12 and the second adhesive layer 31 should not be too thick or too thin. Excessive thickness increases thermal resistance, while insufficient thickness fails to provide good voltage withstand characteristics and results in inadequate adhesion between the two adhesive layers. In one embodiment, the thickness of each of the first adhesive layer 12 and the second adhesive layer 31 is in the range of 25 μm to 100 μm. After hot pressing, the first adhesive layer 12 and the second adhesive layer 31 together constitute a thermally conductive insulating layer, meaning the thermally conductive insulating layer includes both the first adhesive layer 12 and the second adhesive layer 31, and the thickness of the thermally conductive insulating layer is in the range of 50 μm to 200 μm.

[0065] In one embodiment, a reverse fixture 50 can be used to perform hot pressing, such as Figure 4As shown. The so-called complementary jig 50 refers to a jig whose surface has a topography that complements the surface of the heat sink 20. Therefore, during the hot pressing step, when the complementary jig 50 is placed on the heat sink 20, there is no gap between the complementary jig 50 and the heat sink 20, and the complementary jig 50 and the heat sink 20 together form a plate of uniform thickness. During hot pressing, the hot press can apply pressure evenly to the heat sink 20, improving the adhesion between layers in the hot-pressed insulating metal substrate.

[0066] exist Figure 2G In the process, if multiple heat dissipation elements 20 are pressed together, for example Figure 2G If the three heat dissipation elements 20 are shown to be pressed together, the method may further include a cutting step. Figure 2G For example, in one embodiment, cutting can be performed along the cutting line C after lamination to separate the insulating metal substrate and form the final desired product. However, if only one heat dissipation element 20 is laminated, the cutting step is not required. Whether to include this cutting step can be selected based on product design and manufacturing process requirements. After lamination and cutting, a product is formed as shown... Figure 3 The insulating metal substrate 300 shown.

[0067] To achieve good thermal conductivity and electrical properties, and to meet the aforementioned adhesive requirements, the first adhesive layer 12 and the second adhesive layer 31 are made of an adhesive material comprising a polymer component, a thermally conductive filler, a curing agent, and a curing accelerator. The polymer component constitutes between 15% and 60% of the volume of the adhesive material and includes a thermosetting epoxy resin and a modified polymer. The modified polymer improves the impact resistance of the thermosetting epoxy resin and includes thermoplastic plastics, rubbers, or combinations thereof, with the modified polymer constituting between 4% and 45% of the volume of the polymer component. The thermally conductive filler is uniformly dispersed within the polymer component and constitutes between 40% and 85% of the volume of the adhesive material.

[0068] The thermal conductivity of the adhesive material of this invention is approximately 3 W / mK to 15 W / mK, for example, 5 W / mK, 7 W / mK, 10 W / mK, or 12 W / mK. When the adhesive material is formed into a sheet with a thickness of 100 μm, its thermal resistivity is less than 0.5 °C / W or 0.4 °C / W. According to ASTM D2240A, the hardness of the adhesive material of this invention is approximately between 65 A and 98 A, for example, 75 A, 85 A, or 95 A, exhibiting good impact resistance and making it highly suitable for bonding applications with metallic materials. The metallic materials can be copper, aluminum, nickel, iron, tin, gold, silver, or their alloys. After the adhesive material and the metallic material are pressed and cured, the adhesion between the adhesive material and the metallic material is greater than 80 kg / cm².2 Among these, adhesives containing thermoplastic plastics show a more significant improvement in adhesion. Due to the properties of thermoplastic plastics, these adhesives possess the strength and resilience of thermoplastics, allowing them to form strong bonds with metal materials, such as metal electrodes or substrates, with adhesion strengths even exceeding 100 kg / cm². 2 Or 120kg / cm 2 The metallic material comprises iron, aluminum, copper, or alloys thereof. Preferably, when the adhesive material is made into a sheet material with a thickness of 100 μm, its thermal resistivity is less than 0.5 °C / W, and it has good insulation properties capable of withstanding voltages greater than 500 volts, such as 600 volts, 800 volts, 1000 volts, 1200 volts, 1400 volts, 1600 volts, 1800 volts, or 2000 volts. Furthermore, the glass transition temperature Tg of the adhesive layers 12 and 31 made of the adhesive material is greater than 150 °C, for example, in the range of 150 °C to 380 °C.

[0069] exist Figure 2G In the process, the thermally conductive insulating layer formed after hot pressing includes a first adhesive layer 12 and a second adhesive layer 31. The thermal resistivity of the thermally conductive insulating layer is equivalent to the thermal resistivity of a sheet material with the same thickness as the thermally conductive insulating layer, made from the adhesive material. For example, when the thickness of the first adhesive layer 12 and the second adhesive layer 31 are each 50 μm, the thermal resistivity of a 100 μm thick thermally conductive insulating layer is equivalent to the thermal resistivity of a 100 μm thick sheet material made from the adhesive material.

[0070] The thermosetting epoxy resin may include epoxy resins with terminal epoxy functional groups, epoxy resins with side-chain functional groups, or epoxy resins with tetrafunctional groups, or combinations thereof. For example, the thermosetting epoxy resin may include bisphenol A epoxy resin.

[0071] The thermoplastic may be selected from an essentially amorphous thermoplastic resin, such as: phenoxy resin, polysulfone, polyethersulfone, polystyrene, polyphenylene oxide, polyphenylene sulfide, polyamide, polyimide, polyetherimide, polyetherimide / silicone block copolymer, polyurethane, polyester, polycarbonate, acrylic resin (e.g., polymethyl methacrylate, styrene / propylene, and styrene block copolymers)).

[0072] The rubber can be selected from nitrile-butadiene rubber (NBR), such as: carboxy-terminated polybutadiene-acrylonitrile (CTBN), amino-terminated polybutadiene-acrylonitrile (ATBN), hydroxy-terminated polybutadiene-acrylonitrile (HTBN), epoxy-terminated polybutadiene-acrylonitrile (ETBN), vinyl-terminated polybutadiene-acrylonitrile (VTBN), methacrylic-terminated polybutadiene-acrylonitrile, etc.

[0073] The curing agent in the adhesive material of the present invention has a curing temperature above 120°C, or preferably above 150°C, to produce a curing reaction, thereby curing (i.e., crosslinking or catalytic polymerization) the thermosetting epoxy resin. The curing agent can be dicyandiamide and can be used in conjunction with a curing accelerator. Commonly used curing accelerators include urea, urea compounds, imidazole, or boron trifluoride. Alternatively, the curing agent can be selected from isophthaloyl dihydrazide, benzophenone tetracarboxylic dianhydride, diethyltoluene diamine, 3,5-dimethylthio-2,4-toluene diamine, dicyandiamide, or diaminodiphenyl sulfone (DDS). The curing agent may also be selected from substituted dicyandiamides (e.g., 2,6-xylenyl biguanide), solid polyamides, solid aromatic amines, solid anhydride hardeners, phenolic resin hardeners (e.g., poly(p-hydroxystyrene)), amine complexes, trimethylolpropane triacrylates, bismaleimides, cyanate esters, etc. In one embodiment, the curing agent, curing accelerator, and polymer components together constitute between 15% and 60% of the volume percentage of the adhesive material.

[0074] The thermally conductive filler may comprise one or more ceramic powders, which may be selected from nitrides, oxides, or mixtures of the aforementioned nitrides and oxides. The nitride may be zirconium nitride, boron nitride, aluminum nitride, or silicon nitride. The oxide may be alumina, magnesium oxide, zinc oxide, silicon dioxide, or titanium dioxide. Generally, oxides have poor thermal conductivity, while nitrides have low filling amounts; therefore, mixing oxides and nitrides simultaneously can provide complementary effects. The thermally conductive filler is uniformly dispersed in the polymer component and constitutes between 40% and 85% of the volume of the adhesive layer, preferably between 50% and 70%, for example, 50%, 55%, 60%, 65%, 70%, or 80%.

[0075] The insulating metal substrate manufactured by the above method was subjected to cyclic testing. The initial adhesion before and after the cyclic testing were measured, and the appearance of the insulating metal substrate was observed. The results are shown in Table 1 below. The cyclic testing was performed by maintaining the temperature at -40°C and 150°C for 30 minutes each, and then performing 1000 cycles. The circuit pattern layer was a 1mm thick copper layer, and the first and second adhesive layers each had a thickness of 50μm. Generally, the adhesion between layers is related to many factors, such as the pressing conditions, the composition of the layers, and the surface roughness of the layers. Typically, the greater the pressure applied by the hot press, the greater the adhesion between the layers. The test results show that as long as the adhesion between the layers after hot pressing is greater than 80kg / cm², the adhesion between the layers will be stronger. 2 The insulating metal substrate passed the cyclic test without separation between layers. Although the adhesion between layers decreased slightly after the cyclic test, they still remained bonded to each other, as shown in Examples 1, 2, and 3. However, if the adhesion between the two adhesive layers after hot pressing is less than 80 kg / cm², the separation will not occur. 2 For example, the adhesive force shown in Comparative Example 1 is 60 kg / cm. 2 When the insulating metal substrate 300 separates or peels, it is clear that the adhesion between the layers is insufficient.

[0076] Table 1

[0077]

[0078] Table 2 shows the initial adhesion of the insulating metal substrate manufactured according to the above method before and after the cyclic test, as well as the appearance of the insulating metal substrate. Similarly, the cyclic test was performed by maintaining the temperature at -40°C and 150°C for 30 minutes each, and then performing 1000 cycles. The circuit pattern layer had different thicknesses, and the first and second adhesive layers each had a thickness of 50 μm. The test results showed that when the thickness of the circuit pattern layer was in the range of 0.3 mm to 10 mm, the insulating metal substrate could still pass the cyclic test, and there was no peeling between the first adhesive layer and the circuit pattern layer. The thicker the circuit pattern layer, the greater the decrease in adhesion after the cyclic test. In Example 7, when the thickness of the circuit pattern layer was 10 mm, the adhesion decreased by approximately 25% after the cyclic test, from an initial 80 kg / cm². 2 Decreased to 60 kg / cm 2 However, no peeling occurred. Clearly, this invention is suitable for use in copper circuit pattern layers with a thickness of 0.3mm to 10mm.

[0079] Table 2

[0080]

[0081] The examples in Tables 1 and 2 were tested with the first and second adhesive layers each having a thickness of 50 μm. In practical applications, the thickness of each of the first and second adhesive layers can be in the range of 25 μm to 100 μm, for example, 40 μm, 60 μm, or 80 μm. After the above tests, no peeling occurred with adhesive layers of these thicknesses.

[0082] In summary, in general high-power applications, thick circuit pattern layers 14, such as copper layers of 0.3 mm to 10 mm thickness, are typically used, along with heat dissipation elements 20 with protrusions 22. However, conventional manufacturing methods for insulating metal substrates can lead to layer-to-layer separation. This invention increases the adhesion between layers through a series of manufacturing steps. The invention first provides a thermally conductive substrate that has been thermo-pressed, resulting in good adhesion between the metal layer and the first adhesive layer. Furthermore, since the second adhesive layer has the same or similar composition as the first adhesive layer, thermo-pressing ensures a very tight bond between the second and first adhesive layers. Therefore, even though the heat dissipation element 20 has protrusions 22, the good adhesion prevents separation. Moreover, the adhesive material used to form the first adhesive layer 12 and the second adhesive layer 31 is formulated to achieve a thermal conductivity greater than 3 W / mK, and when the adhesive material is made into a sheet material with a thickness of 100 μm, its thermal resistivity is less than 0.5 °C / W. The adhesive material can withstand voltages greater than 500 volts. The glass transition temperature (Tg) of the adhesive layer made of the adhesive material is greater than 150°C. Therefore, this invention is particularly suitable for high-power applications. This invention also utilizes CNC milling technology to remove part of the metal layer 13, which can avoid positioning misalignment problems and improve product yield.

[0083] The present invention also provides an insulating metal substrate 300. See also... Figure 3 The insulating metal substrate 300 includes a circuit pattern layer 14, an encapsulation layer 15, a first adhesive layer 12, a second adhesive layer 31, and a heat dissipation element 20. The encapsulation layer 15 fills the gaps 141 between the metal lines 142 of the circuit pattern layer 14, and its upper surface is flush with the upper surface of the circuit pattern layer 14. The heat dissipation element 20 is located below the circuit pattern layer 14 and the encapsulation layer 15. The first adhesive layer 12 and the second adhesive layer 31 are disposed between the circuit pattern layer 14 and the heat dissipation element 20. The first adhesive layer 12 contacts the circuit pattern layer 14 and the encapsulation layer 15, and the second adhesive layer 31 contacts the heat dissipation element 20. The adhesive force between the first adhesive layer 12 and the second adhesive layer 31 is greater than 80 kg / cm². 2 .

[0084] In one embodiment, the circuit pattern layer 14 is made of copper and has a thickness of 0.3 mm to 10 mm, such as 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm or 9 mm.

[0085] The adhesion between the first adhesive layer 12 and the circuit pattern layer 14 is greater than 80 kg / cm². 2 Even greater than 100 kg / cm 2 Or 120kg / cm 2The adhesion between the second adhesive layer 31 and the heat dissipation element 20 is greater than 80 kg / cm². 2 Even greater than 100 kg / cm 2 Or 120kg / cm 2 .

[0086] The composition of the first adhesive layer 12 and the second adhesive layer 31 has been described in the embodiment shown in Figure 2 and will not be repeated here. Both the first adhesive layer 12 and the second adhesive layer 31 serve as thermally conductive and insulating media for the insulating metal substrate. The first adhesive layer 12 and the second adhesive layer 31 can be bonded together by hot pressing, forming a physical contact between them. This results in an interface being formed between the first adhesive layer 12 and the second adhesive layer 31 after hot pressing, and the first adhesive layer 12 and the second adhesive layer 31 exhibit excellent adhesion, for example, at 80 kg / cm². 2 ~300kg / cm 2 Within the range, especially 100 kg / cm 2 150kg / cm 2 200kg / cm 2 Or 250kg / cm 2 That is, the interface between the first adhesive layer 12 and the second adhesive layer 31 has a strength of 80 kg / cm². 2 ~300kg / cm 2 It exhibits excellent adhesion. Furthermore, the glass transfer temperature (Tg) between the first and second adhesive layers is greater than 150°C.

[0087] In one embodiment, to increase the heat dissipation area and improve heat dissipation efficiency, for example in high-power applications, the heat dissipation element 20 may include a base plate 21 and a plurality of protrusions 22, the protrusions 22 projecting outward in a direction perpendicular to the extension direction of the base plate 21. The protrusions 22 may be cylinders, elliptical cylinders, polygonal prisms, truncated cones, or flat plates, and gaps are provided between the protrusions 22 to allow airflow, thereby dissipating heat. Alternatively, in other embodiments, the heat dissipation element 20 may consist only of a base plate 21, i.e., without protrusions 22. In this case, the base plate 21 has a greater thickness, which facilitates heat conduction along both the horizontal and vertical directions of the base plate 21 and further dissipation to the external environment, thereby achieving an effective heat dissipation effect.

[0088] In summary, this invention provides an insulating metal substrate and its manufacturing method. The invention first provides a thermally conductive substrate that has been thermo-pressed, resulting in good adhesion between the metal layer and the first adhesive layer. Then, a portion of the metal layer is mechanically removed to avoid alignment errors. Because the second adhesive layer has the same or similar composition as the first adhesive layer, thermo-pressing ensures a very tight bond between them. Therefore, according to this invention, the insulating metal substrate not only avoids layer-to-layer separation but also solves the alignment error problem. Furthermore, the insulating metal substrate has good thermal conductivity and a high glass transition temperature (Tg). Therefore, this invention is particularly suitable for high-power applications, providing an effective solution to the problems faced by conventional insulating metal substrates.

[0089] The technical content and features of this invention have been disclosed above. However, those skilled in the art may still make various substitutions and modifications that do not depart from the spirit of this invention based on the teachings and disclosures. Therefore, the scope of protection of this invention should not be limited to what is disclosed in the embodiments, but should include various substitutions and modifications that do not depart from this invention, and is covered by the following claims.

Claims

1. An insulating metal substrate, comprising: A line pattern layer; An encapsulation layer that fills the gaps between the metal lines of the circuit pattern layer, and the upper surface of the encapsulation layer is flush with the upper surface of the circuit pattern layer. First adhesive layer; A second adhesive layer; and A heat dissipation element is located below the circuit pattern layer and the encapsulation layer; The first adhesive layer and the second adhesive layer have no openings and are disposed between the circuit pattern layer and the heat dissipation element. The first adhesive layer contacts the circuit pattern layer and the encapsulation layer, and the second adhesive layer contacts the heat dissipation element. The first adhesive layer and the second adhesive layer are in physical contact and have an adhesion force greater than 80 kg / cm². 2 , The circuit pattern layer contains copper and has a thickness of 0.3mm to 10mm. The first adhesive layer and the second adhesive layer may have the same or different compositions, and Both the first adhesive layer and the second adhesive layer are made of an adhesive material, which includes: A polymeric component, comprising between 15% and 60% by volume of the adhesive material, and including a thermosetting epoxy resin and a modified polymer that improves the impact resistance of the thermosetting epoxy resin, the modified polymer comprising thermoplastic plastics, rubbers or combinations thereof, and the modified polymer comprising between 4% and 45% by volume of the polymeric component. A thermally conductive filler is uniformly dispersed in the polymer component and accounts for between 40% and 85% of the volume of the adhesive material; A curing agent for curing the thermosetting epoxy resin at temperatures above 120°C; and A curing accelerator, comprising urea or its compounds; The thermal conductivity of the adhesive material is greater than 3 W / mK.

2. The insulating metal substrate according to claim 1, wherein the adhesion between the first adhesive layer and the circuit pattern layer is greater than 80 kg / cm². 2 The adhesion between the second adhesive layer and the heat dissipation element is greater than 80 kg / cm². 2 .

3. The insulating metal substrate according to claim 1, wherein the glass transition temperature Tg of the first adhesive layer and the second adhesive layer is greater than 150°C.

4. The insulating metal substrate according to claim 1, wherein the thickness of each of the first adhesive layer and the second adhesive layer is in the range of 25µm to 100µm, and the adhesion between the first adhesive layer and the second adhesive layer is 80 kg / cm². 2 ~300 kg / cm 2 Within the range.

5. The insulating metal substrate according to claim 1, wherein when the adhesive material is made into a sheet material with a thickness of 100µm, the thermal resistivity of the adhesive material is less than 0.5℃ / W and can withstand a voltage greater than 500 volts.

6. The insulating metal substrate according to claim 1, wherein the thermally conductive filler comprises one or more ceramic powders.

7. The insulating metal substrate according to claim 1, wherein the thermally conductive filler is selected from zirconium nitride, boron nitride, aluminum nitride, silicon nitride, aluminum oxide, magnesium oxide, zinc oxide, silicon dioxide, titanium dioxide, or mixtures thereof.

8. The insulating metal substrate according to claim 1, wherein the heat dissipation element includes a base plate and a plurality of protrusions, the protrusions protruding outward in a direction perpendicular to the extending direction of the base plate, and the protrusions having gaps between them.

9. A method for manufacturing an insulating metal substrate, comprising: A thermally conductive substrate is provided, which comprises, from bottom to top, a metal substrate, a first adhesive layer and a metal layer; A portion of the metal layer is removed to form a circuit pattern layer that exposes a portion of the first adhesive layer. An encapsulation layer is formed on the circuit pattern layer, and the encapsulation layer fills the gaps between the metal lines of the circuit pattern layer. Remove the top portion of the encapsulation layer so that the upper surface of the encapsulation layer is flush with the upper surface of the circuit pattern layer; Remove the metal substrate; A heat dissipation element is provided, wherein a second adhesive layer is disposed on the heat dissipation element; and The second adhesive layer is bonded to the first adhesive layer, such that physical contact is formed between the first adhesive layer and the second adhesive layer and the adhesion force is greater than 80 kg / cm². 2 .

10. The method for manufacturing an insulating metal substrate according to claim 9, wherein the circuit pattern layer comprises copper and has a thickness of 0.3 mm to 10 mm.

11. The method of manufacturing an insulating metal substrate according to claim 9, wherein a portion of the metal layer is removed using CNC milling technology.

12. The method of manufacturing an insulating metal substrate according to claim 9, wherein the encapsulation layer is formed by potting, screen printing, spraying or injection molding, the encapsulation layer comprising an insulating material selected from epoxy molding compound, solder resist, thermally conductive ink, epoxy resin, polyetheretherketone or polyethersulfone.

13. The method for manufacturing an insulating metal substrate according to claim 9, wherein the heat dissipation element includes a base plate and a plurality of protrusions, the protrusions protruding outward in a direction perpendicular to the extending direction of the base plate, and the protrusions having gaps between them.

14. The method for manufacturing an insulating metal substrate according to claim 9, wherein the glass transition temperature Tg of the first adhesive layer and the second adhesive layer is greater than 150°C.

15. The method for manufacturing an insulating metal substrate according to claim 9, wherein after lamination, the adhesion between the first adhesive layer and the circuit pattern layer is greater than 80 kg / cm². 2 The adhesion between the second adhesive layer and the heat dissipation element is greater than 80 kg / cm². 2 .

16. The method for manufacturing an insulating metal substrate according to claim 9, wherein the thickness of each of the first adhesive layer and the second adhesive layer is in the range of 25µm to 100µm, and the adhesion between the first adhesive layer and the second adhesive layer is 80kg / cm². 2 ~300 kg / cm 2 Within the range.

17. The method of manufacturing an insulating metal substrate according to claim 9, wherein a reverse fixture is placed on the heat dissipation element and thermoforming is performed to attach the second adhesive layer to the first adhesive layer.

18. The method for manufacturing an insulating metal substrate according to claim 9, wherein the first adhesive layer and the second adhesive layer have the same or different compositions.

19. The method for manufacturing an insulating metal substrate according to claim 18, wherein both the first adhesive layer and the second adhesive layer are made of an adhesive material, the adhesive material comprising: A polymeric component, comprising between 15% and 60% by volume of the adhesive material, and including a thermosetting epoxy resin and a modified polymer that improves the impact resistance of the thermosetting epoxy resin, the modified polymer comprising thermoplastic plastics, rubbers or combinations thereof, and the modified polymer comprising between 4% and 45% by volume of the polymeric component. A thermally conductive filler is uniformly dispersed in the polymer component and accounts for between 40% and 85% of the volume of the adhesive material; A curing agent for curing the thermosetting epoxy resin at temperatures above 120°C; and A curing accelerator, comprising urea or its compounds; The thermal conductivity of the adhesive material is greater than 3 W / mK.

20. The method for manufacturing an insulating metal substrate according to claim 19, wherein when the adhesive material is made into a sheet material with a thickness of 100µm, the thermal resistivity of the adhesive material is less than 0.5℃ / W and can withstand a voltage greater than 500 volts.

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