Heat dissipation substrate and preparation method thereof

Abstract

The present invention discloses a heat dissipation substrate and a preparation method thereof. The heat dissipation substrate of an embodiment includes a ceramic plate, a resin package and a first conductive circuit; the first conductive circuit is embedded in the resin package, and the surface of the first conductive circuit is exposed from the resin package; wherein the first conductive circuit includes a bottom circuit connected to the ceramic plate and a thickened circuit stacked and welded on the bottom circuit, and the thickened circuit has a thickness greater than that of the bottom circuit. The preparation method of the embodiment includes: making a bottom circuit on the first surface of the ceramic plate, stacking and welding the thickened circuit on the bottom circuit, and making the resin package by an injection molding process. The present invention welds the thickened circuit to the bottom circuit, which can effectively reduce the stress between the interface of the first conductive circuit and the ceramic plate, thereby increasing the thickness of the first conductive circuit and its current carrying capacity; the first conductive circuit is embedded in the resin package, so that the heat dissipation substrate has good electrical insulation properties.

Description

Technical Field

[0001] The invention relates to a heat dissipation substrate and a preparation method thereof. Background Art

[0002] Ceramic heat dissipation substrates are made by metallizing circuits on the surface of ceramic plates, which have excellent electrical insulation and thermal conductivity. In the existing technology, sintering or direct brazing processes are generally used to make the circuit layer on the ceramic plate.

[0003] For example, Chinese patent document CN101414654A discloses a process for manufacturing a high-power LED ceramic heat dissipation substrate, which includes the following steps: (1) forming a uniform and dense oxide film on the surface of copper powder, and mixing it with an organic carrier at a solid mass ratio of 70-80:20-30, and then rolling it into a slurry; (2) printing or coating the above slurry on a ceramic substrate to form a metal conductor film and drying it; (3) sintering: the sintering peak temperature is 1060-1080°C.

[0004] In prior art technologies such as those disclosed in the aforementioned patents, due to the significant difference in thermal expansion coefficients between ceramic and metal, thicker circuit layers can generate significant interfacial stress at the interface between the metal circuit layer and the ceramic substrate during thermal cycling, leading to cracks. Furthermore, the lack of an insulating medium, such as resin, between the circuits formed on the ceramic substrate's surface results in poor electrical insulation performance. Summary of the Invention

[0005] The main purpose of the present invention is to provide a heat dissipation substrate having better electrical insulation performance and capable of effectively reducing the interface stress between the circuit layer and the ceramic plate, and a preparation method thereof.

[0006] In order to achieve the above-mentioned main objectives, the first aspect of the present invention provides a heat dissipation substrate, including a ceramic board, a resin package and a first conductive circuit; wherein the first conductive circuit is embedded in the resin package, and the surface of the first conductive circuit is exposed from the resin package; the first conductive circuit includes a bottom circuit connected to the ceramic board and a thickened circuit welded on the bottom circuit by welding material, and the thickened circuit has a thickness greater than that of the bottom circuit.

[0007] In the above technical solution, the thickened circuit with a larger thickness is welded on the bottom circuit. The welding material can buffer the thermal stress generated by the thickened circuit during the hot and cold cycle, thereby reducing the stress at the interface between the first conductive circuit and the ceramic plate, avoiding or reducing the defect of cracks in the product; the first conductive circuit is embedded in the resin package, so that the heat dissipation substrate has good electrical insulation properties.

[0008] According to a specific embodiment of the present invention, the thickness of the bottom circuit is 10 μm to 100 μm, preferably 10 μm to 50 μm; the thickness of the thickened circuit is 1 mm to 6 mm, preferably 2 mm to 5 mm.

[0009] According to a specific embodiment of the present invention, a second conductive circuit is provided on the surface of the resin package.

[0010] According to a specific embodiment of the present invention, the second surface of the ceramic plate is connected to a metal bottom plate.

[0011] Preferably, each metal base plate is connected to multiple ceramic plates, or each ceramic plate is connected to multiple metal base plates. Wherein, arranging the metal base plates or ceramic plates in blocks can further reduce the possibility of cracks in the product.

[0012] To achieve the above-mentioned primary objective, a second aspect of the present invention provides a method for preparing a heat dissipation substrate. The heat dissipation substrate includes a ceramic plate, a resin package, and a first conductive circuit, wherein the first conductive circuit is embedded in the resin package and a surface of the first conductive circuit is exposed from the resin package. The preparation method includes the following steps:

[0013] S1, etching the metal layer formed on the first surface of the ceramic board to produce a bottom layer circuit;

[0014] S2. Using welding material, stack and weld the processed thickened circuit onto the bottom circuit to form a first conductive circuit;

[0015] S3. Making a resin package.

[0016] Preferably, the resin package is manufactured by a mold injection molding process.

[0017] According to a specific embodiment of the present invention, the above-mentioned preparation method further includes the step of forming a second conductive circuit on the surface of the resin package.

[0018] According to a specific embodiment of the present invention, the above-mentioned preparation method further includes the step of connecting a metal base plate to the second surface of the ceramic plate.

[0019] According to a specific embodiment of the present invention, in step S2, the thickened circuit is soldered to the bottom circuit using tin alloy solder, and the thickness of the tin alloy solder is 0.2 mm to 0.6 mm.

[0020] In the preparation method of the heat dissipation substrate of the present invention, the thickened circuit that has been processed and formed is welded to the bottom circuit using welding material. The welding material can buffer the thermal stress generated by the thickened circuit during the hot and cold cycle, thereby reducing the stress at the interface between the first conductive circuit and the ceramic plate, avoiding or reducing the defect of cracks in the product; further, the gaps between the first conductive circuits are filled with a resin package, so that the heat dissipation substrate has good electrical insulation properties.

[0021] In order to more clearly illustrate the purpose, technical solutions and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 2 is a schematic structural diagram of a heat dissipation substrate according to an embodiment of the present invention;

[0023] Figure 2 This is a flow chart of the preparation of Example 1 of the heat dissipation substrate of the present invention;

[0024] Figure 3 It is a schematic diagram of the structure after etching the bottom layer circuit on the first surface of the ceramic board;

[0025] Figure 4 This is a schematic diagram of the structure after welding thickened circuits on the bottom circuit;

[0026] Figure 5 It is a schematic diagram of the structure after the resin package is injection molded;

[0027] Figure 6 This is a schematic diagram of the structure after a second conductive circuit is formed on the surface of the resin package;

[0028] Figure 7 2 is a schematic structural diagram of a heat dissipation substrate according to an embodiment of the present invention;

[0029] Figure 8 2 is a schematic structural diagram of a heat dissipation substrate according to a third embodiment of the present invention;

[0030] Figure 9 It is a structural diagram of embodiment 4 of the heat dissipation substrate of the present invention.

[0031] It should be noted that, in order to clearly illustrate the structure to be expressed, different parts in the drawings may not be depicted to the same scale. Therefore, unless explicitly stated, the contents expressed in the drawings do not constitute a limitation on the sizes and proportions of the various parts of the heat dissipation substrate. DETAILED DESCRIPTION

[0032] The following description sets forth many specific details to facilitate a full understanding of the present invention, but the present invention may also be implemented in other variations based on these details. Therefore, other possible implementations that may be known to those skilled in the art based on the following embodiments are all within the scope of protection of the present invention.

[0033] Example 1

[0034] like Figure 1 As shown, the heat dissipation substrate of Example 1 includes a metal base plate 1, a ceramic plate 2, a first conductive circuit 3, a second conductive circuit 4 and a resin package 5; wherein the metal base plate 1 and the first conductive circuit 3 are respectively connected to two opposite surface sides of the ceramic plate 2, the second conductive circuit 4 is formed on the surface of the resin package 5, and the first conductive circuit 3 is embedded in the resin package 5, and the surface of the first conductive circuit 3 is exposed from the resin package 5.

[0035] In the present invention, the ceramic plate 2 can be a silicon nitride, aluminum nitride or aluminum oxide ceramic plate, preferably an aluminum nitride ceramic plate. Further, the thickness of the ceramic plate 2 can be 0.25 mm to 2.0 mm, but the present invention is not limited thereto.

[0036] In the present invention, the metal base plate 1 may be a copper plate, an aluminum plate, or an aluminum-copper composite plate, and its thickness is not limited. In some embodiments, the metal base plate 1 may be formed with fluid channels to allow a heat-conducting fluid to flow through the metal base plate 1 during use to promote heat dissipation. In other embodiments, the metal base plate 1 may be formed with non-planar structures such as heat dissipation fins to increase the heat dissipation area. Furthermore, the metal base plate 1 may also be formed with both flow channels and heat dissipation fins.

[0037] The metal base plate 1 is connected to the second surface of the ceramic plate 2 via a welding material 11. Specifically, a metal layer 21 for connecting to the metal base plate 1 is provided on the second surface of the ceramic plate 2. The metal layer 21 may include a non-copper metal connection layer and a copper metal connection layer sequentially connected to the second surface of the ceramic plate 2. The metal base plate 1 is welded to the copper metal connection layer. The non-copper metal connection layer may be a Ti, Zr, Hf, and / or Cr metal layer.

[0038] The first conductive trace 3 is connected to the first surface of the ceramic board 2. Specifically, the first conductive trace 3 includes a bottom trace 31 connected to the ceramic board 2 and a thickened trace 32 stacked and welded on the bottom trace 31. The thickened trace 32 is thicker than the bottom trace 31, and the two traces can form an identical pattern. The bottom trace can have a thickness of 10 μm to 100 μm, preferably 10 μm to 50 μm, for example, approximately 35 μm. The thickened trace 32 can have a thickness of 1 mm to 6 mm, preferably 2 mm to 5 mm.

[0039] The thickened circuit 32 is soldered to the bottom circuit 31 using a soldering material 33, such as tin alloy solder. The thickness of the soldering material 33 can be 0.2 mm to 0.5 mm. The thicker thickened circuit 32 is soldered to the bottom circuit 31 using the soldering material 33. The soldering material 33 can buffer the thermal stress generated by the thickened circuit 32 during thermal cycling, thereby reducing stress at the interface between the first conductive circuit 3 and the ceramic plate 2, thereby avoiding or reducing crack defects in the product.

[0040] Further, if Figure 1 As shown, the heat dissipation substrate further includes a resin package 5 , and the surface of the first conductive trace 3 is exposed from the resin package 5 . The second conductive trace 4 is formed on the surface of the resin package 5 and is electrically connected to the first conductive trace 3 .

[0041] Next, combine Figures 2 to 6 The method for preparing the heat dissipation substrate in Example 1 is described.

[0042] like Figure 2 As shown, the preparation method of Example 1 includes the steps of etching the metal layer on the first surface of the ceramic plate to form a bottom layer circuit. Figure 3 As shown, a ceramic board 2 having metal layers on both sides is provided. The metal layer on the first surface of the ceramic board 2 is etched to obtain a bottom layer of circuitry 31. The metal layer 21 on the second surface of the ceramic board 2 is not etched. In an embodiment of the present invention, the metal layer on the surface of the ceramic board 2 may include a non-copper metal layer and a copper metal layer sequentially disposed on the surface of the ceramic board 2. The non-copper metal layer may be a Ti, Zr, Hf, and / or Cr circuit layer.

[0043] Then, if Figure 2 As shown, the preparation method of the embodiment includes the steps of stacking and welding the thickened circuit that has been processed and formed on the bottom circuit. Specifically, as Figure 4 As shown, the processed thickened circuit 32 is stacked and welded on the bottom circuit 31 using welding material 33 to form a first conductive circuit 3; wherein the thickened circuit 32 can be made by mechanical cutting, laser cutting, punching, etc. of a copper plate of corresponding thickness.

[0044] Then, if Figure 2 As shown in FIG, the preparation method of the embodiment includes the steps of forming a resin package body by a mold injection molding process. Figure 5As shown, the resin package 5 obtained by the mold injection molding process has an integrated structure, and the surface of the resin package 5 and the first conductive path 3 are flush. In other embodiments of the present invention, the resin package 5 can also be obtained by a circuit board lamination process, in which case the resin package has a layered structure. Among them, the mold injection molding process is particularly preferred because it has the advantages of simple production process, high production efficiency and yield rate, and low cost.

[0045] Then, if Figure 2 and 6 As shown, the manufacturing method of the embodiment includes the step of forming a second conductive circuit on the surface of the resin package. Specifically, a metal layer can be deposited on the surface of the resin package and the first conductive circuit 3 by sputtering or chemical plating plus electroplating. This metal layer is then etched to form a second conductive circuit 4 electrically connected to the first conductive circuit 3, and a device pad is formed at the device connection position of the first conductive circuit 3.

[0046] Finally, the metal base plate 1 is welded on the metal layer 21 on the second surface of the ceramic plate 2 to obtain Figure 1 In other embodiments of the preparation method of the present invention, the welding of the metal base plate 1 and the welding of the thickened circuit 32 can also be performed simultaneously.

[0047] Example 2

[0048] like Figure 7 As shown, the difference between Example 2 and Example 1 is that in Example 2, each metal base plate 1 is connected to multiple ceramic plates 2, that is, the ceramic plates 2 of Example 1 are divided into blocks to reduce the thermal stress generated by the ceramic plates 2 during operation, further reducing the possibility of cracks in the product.

[0049] When preparing the heat dissipation substrate of Example 2, the ceramic plate 2 with the bottom layer circuit 31 may be first welded to the metal base plate 1 , and then the thickened circuit 32 may be laminated and welded on the bottom layer circuit 31 .

[0050] Example 3

[0051] like Figure 8 As shown, the difference between Example 3 and Example 1 is that in Example 3, each ceramic plate 2 is connected to multiple metal base plates 1, that is, the metal base plates 1 of Example 1 are divided into blocks, which is also beneficial to further reduce the possibility of cracks in the product, especially to avoid or reduce the occurrence of cracks between the metal base plates 1 and the ceramic plates 2.

[0052] Example 4

[0053] like Figure 9As shown, the difference between Example 4 and Example 1 is that the surface of the resin package 5 in Example 4 does not have the second conductive circuit 4.

[0054] In summary, in the present invention, the first conductive circuit comprises a base circuit and a thickened circuit soldered to the base circuit. The solder material between the base circuit and the thickened circuit effectively buffers and reduces stress at the interface between the first conductive circuit and the ceramic plate, enabling the fabrication of a thicker first conductive circuit to increase the current-carrying capacity of the ceramic heat dissipation substrate. Furthermore, embedding the first conductive circuit within a resin encapsulation body yields a heat dissipation substrate with excellent electrical insulation properties.

[0055] Although the present invention has been described above through embodiments, it should be understood that the above embodiments are only used to exemplify the possible implementation schemes of the present invention and should not be interpreted as limiting the scope of protection of the present invention. Any equivalent changes made by those skilled in the art in accordance with the present invention should also be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a heat dissipation substrate; wherein: The heat dissipation substrate includes a ceramic plate, a resin package, and a first conductive circuit, wherein the first conductive circuit is embedded in the resin package and a surface of the first conductive circuit is exposed from the resin package. The preparation method includes the following steps: S1. Etching the metal layer formed on the first surface of the ceramic plate to produce a bottom layer circuit; wherein the thickness of the ceramic plate is 0.25 mm to 2.0 mm; S2. Using welding material, stack and weld the processed thickened circuit onto the bottom circuit to form the first conductive circuit; wherein the bottom circuit has a thickness of 10 μm to 100 μm, and the thickened circuit has a thickness of 1 mm to 6 mm, and the thickened circuit has the same pattern as the bottom circuit; S3, manufacturing the resin package; wherein the surface of the resin package is flush with the surface of the first conductive circuit; Fabricating a second conductive circuit electrically connected to the first conductive circuit on the surface of the resin package body, and forming a device pad at a device connection position of the first conductive circuit; In step S2, the thickened circuit is soldered to the bottom circuit by tin alloy solder, and the thickness of the tin alloy solder is 0.2 mm to 0.6 mm; The preparation method further comprises the step of connecting a metal base plate to the second surface of the ceramic plate, wherein the metal base plate is formed with fluid channels and / or heat dissipation fins; The second surface of the ceramic plate is provided with a metal layer for connecting to the metal base plate, and the metal layer includes a non-copper metal connection layer and a copper metal connection layer connected in sequence to the second surface of the ceramic plate, and the metal base plate is welded to the copper metal connection layer.

2. The preparation method according to claim 1, wherein The resin package is manufactured by a mold injection molding process.

3. The preparation method according to claim 1, wherein The ceramic plates are arranged in blocks, and each of the metal base plates is connected to a plurality of the ceramic plates; or the metal base plates are arranged in blocks, and each of the ceramic plates is connected to a plurality of the metal base plates.

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