Ceramic substrate and power module heat dissipation module

Abstract

The utility model discloses a ceramic substrate and a power module radiating module, and relates to the technical field of power devices, the ceramic substrate comprises a ceramic base layer, a first copper-clad layer and a second copper-clad layer, the ceramic base layer is provided with a first surface and a second surface which are arranged oppositely, and the first surface is arranged close to a heat source; the first copper-clad layer is arranged on the first surface of the ceramic base layer; the second copper-clad layer is arranged on the second surface of the ceramic base layer; wherein the projection area formed by orthographic projection of the first copper-clad layer on the ceramic base layer is S1, the projection area formed by orthographic projection of the second copper-clad layer on the ceramic base layer is S2, and S2 is greater than S1. The utility model aims to improve the bending resistance of the ceramic substrate.

Description

Technical Field

[0001] The utility model relates to the technical field of power devices, in particular to a ceramic substrate and a power module heat dissipation module. Background Art

[0002] Double-sided copper-clad ceramic substrate is a basic electronic material with excellent properties such as high-temperature stability, corrosion resistance, high thermal conductivity, and high mechanical strength. It has been widely used in the power semiconductor industry, automotive electronics, solar panels and other fields.

[0003] Traditional double-sided copper-clad ceramic substrates typically consist of a ceramic substrate and a first copper layer, laminated on the upper surface and a second copper layer, respectively, on the lower surface. During the heating and cooling processes, internal stresses are generated between the first copper sheet, the ceramic substrate, and the second copper sheet due to the thermal expansion coefficient of copper being several dozen times greater than that of ceramic. Consequently, the ceramic substrate must withstand the stresses exerted by the first and second copper sheets, both from temperature cycles and the varying thermal expansion coefficients.

[0004] However, due to the different heating conditions of the first copper sheet and the second copper sheet during use, the stress exerted by the first copper sheet on the entire ceramic sheet is different from the stress exerted by the second copper sheet on the entire ceramic board. That is, there is a certain difference in the magnitude of the stress exerted by the first copper sheet and the lower copper sheet on the ceramic board, which causes the entire double-sided copper-clad ceramic substrate to bend to a large extent toward one side. Utility Model Content

[0005] The main purpose of the utility model is to provide a ceramic substrate and a power module heat dissipation module, aiming to improve the bending resistance energy of the ceramic substrate.

[0006] To achieve the above-mentioned purpose, the present invention provides a ceramic substrate comprising:

[0007] a ceramic substrate having a first surface and a second surface disposed opposite to each other;

[0008] a first copper clad layer, the first copper clad layer being disposed on a first surface of the ceramic base layer; and

[0009] a second copper-clad layer, the second copper-clad layer being disposed on the second surface of the ceramic base layer;

[0010] The projected area of ​​the first copper cladding layer formed by the orthographic projection on the ceramic base layer is S1, the projected area of ​​the second copper cladding layer formed by the orthographic projection on the ceramic base layer is S2, and S2>S1.

[0011] In one embodiment, 1.2≤S2 / S1≤1.5.

[0012] In one embodiment, 0.3 mm ≤ t1 <t2≤0.4mm。

[0013] In one embodiment, t1>t2.

[0014] In one embodiment, an anti-oxidation layer is provided on a side of the first copper cladding layer facing away from the ceramic base layer and a side of the second copper cladding layer facing away from the ceramic base layer.

[0015] In one embodiment, the thickness of the anti-oxidation layer is t4, 3um≤t4≤7um.

[0016] The present invention also provides a power module heat dissipation module, the power module heat dissipation module comprising:

[0017] heat sink;

[0018] power components; and

[0019] A heat-conducting medium, the heat-conducting medium comprising a first connecting layer, a second connecting layer, and the ceramic substrate as described above; the first connecting layer is arranged close to the first copper cladding layer on a side facing the ceramic substrate, and the first connecting layer is connected to the power element on a side facing away from the ceramic substrate; the second connecting layer is arranged close to the second copper cladding layer on a side facing the ceramic substrate, and the second connecting layer is connected to the heat sink on a side facing away from the ceramic substrate.

[0020] In one embodiment, the first connecting layer is a welding layer or an adhesive layer; and

[0021] The second connection layer is a welding layer or an adhesive layer.

[0022] In one embodiment, the first connecting layer is the adhesive layer, and the second connecting layer is the welding layer.

[0023] The ceramic substrate design proposed in this utility model achieves the goal of improving the ceramic substrate's bending resistance by increasing the difference in copper cladding area between the two sides of the ceramic base layer. Specifically, the area of ​​the second copper cladding layer, which is farther away from the heat source, is set to be larger than the area of ​​the first copper cladding layer, which is closer to the heat source. Since the first copper cladding layer is closer to the heat source, it will be subjected to higher heat and the resulting greater stress. At the same time, the larger area of ​​the second copper cladding layer will also generate relatively greater stress when thermally expanded. This can balance the stress difference between the two sides of the ceramic base layer, thereby at least partially offsetting the original stress tendency of the ceramic substrate to bend, thereby effectively reducing the degree of bending of the ceramic substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0025] Figure 1 A schematic structural diagram of an embodiment of a ceramic substrate provided by the present invention;

[0026] Figure 2 A structural schematic diagram of another embodiment of the ceramic substrate provided by the present invention;

[0027] Figure 3 A structural schematic diagram of another embodiment of the ceramic substrate provided by the present invention;

[0028] Figure 4 This is a structural schematic diagram of an embodiment of a power module heat dissipation module provided by the utility model.

[0029] Description of Figure Numbers:

[0030] 100. Power module heat dissipation module; 1. Thermal conductive medium; 11. First connection layer; 12. Second connection layer; 13. Ceramic substrate; 131. Ceramic base layer; 132. First copper cladding layer; 133. Second copper cladding layer; 2. Radiator; 3. Power element.

[0031] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0033] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0034] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0035] The present utility model provides a ceramic substrate 13 .

[0036] See also Figures 1 to 3 In one embodiment of the present invention, the ceramic substrate 13 includes a ceramic base layer 131, a first copper clad layer 132 and a second copper clad layer 132. The ceramic base layer 131 has a first surface and a second surface arranged opposite to each other, and the first surface is arranged close to the heat source; the first copper clad layer 132 is arranged on the first surface of the ceramic base layer 131; the second copper clad layer 132 is arranged on the second surface of the ceramic base layer 131; wherein the projection area formed by the orthographic projection of the first copper clad layer 132 on the ceramic base layer 131 is, and the projection area formed by the orthographic projection of the second copper clad layer 132 on the ceramic base layer 131 is S2, and S2>S1.

[0037] The design of the ceramic substrate 13 proposed in this invention achieves improved bending resistance by increasing the difference in copper cladding area between the two sides of the ceramic base layer 131. Specifically, the area of ​​the second copper cladding layer 132, which is farther from the heat source, is set to be larger than the area of ​​the first copper cladding layer 132, which is closer to the heat source. Because the first copper cladding layer 132 is closer to the heat source, it will be subjected to higher heat and the resulting greater stress. At the same time, the larger area of ​​the second copper cladding layer 132 will also generate relatively greater stress when thermally expanded. This balances the stress difference between the two sides of the ceramic base layer 131, thereby at least partially offsetting the original stress tendency of the ceramic substrate 13 to bend, thereby effectively reducing the degree of bending of the ceramic substrate 13.

[0038] In one embodiment of the present application, the thickness of the first copper clad layer 132 is t1, and the thickness of the second copper clad layer 132 is t2, where 0.3 mm ≤ t1 ≤ 0.4 mm, and 0.3 mm ≤ t2 ≤ 0.4 mm. This thickness design ensures that the first copper clad layer 132 and the second copper clad layer 132 have sufficient thermal conductivity while being easy to manufacture, thereby improving the overall performance and reliability of the ceramic substrate 13.

[0039] Please refer to Figure 3 In one embodiment of the present application, t1>t2, that is, the thickness of the second copper cladding layer 132 is reduced. On the one hand, reducing the thickness of the second copper cladding layer 132 can conduct heat more effectively, thereby reducing the temperature gradient caused by heat accumulation and improving the heat conduction efficiency. In addition, reducing the thickness of the second copper cladding layer 132 helps to better balance the stress on both sides of the substrate during the thermal cycle, thereby effectively reducing the bending deformation of the ceramic substrate 13 and improving its overall stability and service life.

[0040] Please refer to Figure 2 In one embodiment of the present application, the thickness of the ceramic substrate 131 is t3, where 0.3 mm ≤ t3 ≤ 0.4 mm. The primary purpose of limiting the thickness of the ceramic substrate 131 to the range of 0.3 mm to 0.4 mm is to ensure that the ceramic substrate 131 has good thermal conductivity while also increasing the thickness of the ceramic substrate 131 to meet the requirements for its overall rigidity. This enhances the ceramic substrate 131's ability to resist deformation, thereby reducing bending deformation. In a preferred embodiment of the present application, the thickness of the ceramic substrate 131 is 0.32 mm.

[0041] If the difference in copper clad area on both sides of the ceramic substrate 131 is too large, it will lead to uneven stress distribution, thereby increasing the risk of substrate bending deformation. However, if the area difference is too small, it may not be enough to balance the stress caused by the mismatch in thermal expansion coefficients, thereby affecting the mechanical properties of the substrate. Therefore, in one embodiment of the present application, 1.2≤S2 / S1≤1.5.

[0042] In order to prevent oxidation reactions between the copper layer and the ceramic base layer 131, which may lead to a decrease in connection performance or defects, in one embodiment of the present application, an anti-oxidation layer is provided on the side of the first copper clad layer 132 facing away from the ceramic base layer 131 and the side of the second copper clad layer 132 facing away from the ceramic base layer 131. The anti-oxidation layer can effectively prevent the oxidation reaction between the copper layer and the ceramic base layer 131, thereby maintaining the thermal conductivity and mechanical strength of the copper layer, extending the service life of the ceramic substrate 13, and ensuring the stable performance of the ceramic substrate 13 in complex application scenarios. The anti-oxidation layer is usually a gold plating process with a nickel base. Nickel has good electrical conductivity and mechanical strength, and has high thermal stability and corrosion resistance. The nickel base can serve as a transition layer, which helps to improve the adhesion and durability of the gold plating. Gold has very high electrical conductivity and excellent chemical stability and is not easily oxidized. Therefore, it can provide long-term protection and prevent the copper layer from reacting with oxygen in the air to form copper oxide, thereby maintaining the conductive properties and mechanical integrity of the copper layer. In other embodiments, the anti-oxidation layer can also adopt a palladium-gold structure.

[0043] In one embodiment of the present application, the anti-oxidation layer includes a nickel layer and a gold-plated layer. The thickness of the nickel layer is t4, 3um≤t4≤7um, and the thickness range of 3μm to 7μm ensures that the nickel layer can provide sufficient protection while avoiding the additional cost and weight that may be caused by an overly thick nickel layer.

[0044] Please refer to Figure 4 The present application also provides a power module heat dissipation module 100, which includes a heat sink 2, a power element 3, and a heat conducting medium 1. The heat conducting medium 1 includes a first connecting layer 11, a second connecting layer 12, and a ceramic substrate 13. The specific structure of the ceramic substrate 13 is referred to the above embodiment. Since the power module heat dissipation module 100 adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which are not described in detail here. Among them, the first connecting layer 11 is arranged on the side facing the ceramic substrate 13, close to the first copper clad layer 132, and the side of the first connecting layer 11 facing away from the ceramic substrate 13 is connected to the power element 3; the second connecting layer 12 is arranged on the side facing the ceramic substrate 13, close to the second copper clad layer 132, and the side of the second connecting layer 12 facing away from the ceramic substrate 13 is connected to the heat sink 2.

[0045] In one embodiment of the present application, the first connection layer 11 is a welding layer or an adhesive layer; the second connection layer 12 is a welding layer or an adhesive layer. It is understood that the above embodiment includes four solutions, namely: the first connection layer 11 is a welding layer, and the second connection layer 12 is a welding layer; the first connection layer 11 is a welding layer, and the second connection layer 12 is an adhesive layer; the first connection layer 11 is an adhesive layer, and the second connection layer 12 is a welding layer; the first connection layer 11 is an adhesive layer, and the second connection layer 12 is an adhesive layer. It should be noted that the function of the adhesive layer is to firmly bond the first connection layer 11 to the power element 3 or the second connection layer 12 to the heat sink 2. The adhesive layer can fill microscopic gaps and reduce air gaps, allowing heat to be conducted more directly and efficiently from the heat source to the heat sink 2, thereby providing better thermal conductivity than traditional mechanical fixing methods. Compared with traditional thermal conductive gels, the adhesive layer produces fewer bubbles and gaps when achieving the bonding function, thereby reducing the interface impedance in the heat conduction path. In addition, the bonding technology does not require complex alignment or fasteners, which can simplify the assembly process, make the production process faster, reduce assembly costs, and improve production efficiency. The material of the adhesive layer can be silicone adhesive, epoxy resin adhesive or UV curing adhesive. agent, etc.; the function of the welding layer is to firmly connect the ceramic substrate 13 and the power element 3 or the heat sink 2 to ensure that the heat conduction path is as short as possible and the impedance is low. On the one hand, welding can also provide better structural strength than traditional mechanical fixing methods, and can improve the stability of the power module heat dissipation module 100 in high temperature or vibration environments. On the other hand, welding can achieve almost seamless interface contact, which helps to reduce the thermal resistance caused by the interface gap, thereby improving the heat conduction efficiency. When welding, it is necessary to use low-temperature solder to reduce the welding temperature. At the same time, a vacuum welding process is required to control the void rate of the solder joint.

[0046] In a preferred embodiment of the present application, the first connection layer 11 is an adhesive layer, and the second connection layer 12 is a soldering layer. That is, one side of the ceramic substrate 13 is connected to the power element 3 using soldering, and the other side of the ceramic substrate 13 is bonded to the heat sink 2 using adhesive. This effectively reduces the process thermal resistance of the power element 3 and improves heat dissipation efficiency.

[0047] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A ceramic substrate, characterized in that The ceramic substrate comprises: a ceramic substrate having a first surface and a second surface disposed opposite to each other, wherein the first surface is disposed near a heat source; a first copper clad layer, the first copper clad layer being disposed on a first surface of the ceramic base layer; and a second copper-clad layer, the second copper-clad layer being disposed on the second surface of the ceramic base layer; The projected area of ​​the first copper cladding layer formed by the orthographic projection on the ceramic base layer is S1, the projected area of ​​the second copper cladding layer formed by the orthographic projection on the ceramic base layer is S2, and S2>S1.

2. The ceramic substrate according to claim 1, wherein The thickness of the first copper cladding layer is t1, the thickness of the second copper cladding layer is t2, and t1>t2.

3. The ceramic substrate according to claim 2, wherein 0.3mm≤t2 <t1≤0.4mm。 4. The ceramic substrate according to claim 1, wherein The thickness of the ceramic base layer is t3, 0.3mm≤t3≤0.4mm.

5. The ceramic substrate according to claim 1, wherein 1.2≤S2 / S1≤1.

5.

6. The ceramic substrate according to any one of claims 1 to 5, wherein An anti-oxidation layer is provided on a side of the first copper cladding layer facing away from the ceramic base layer and a side of the second copper cladding layer facing away from the ceramic base layer.

7. The ceramic substrate according to claim 6, wherein The anti-oxidation layer includes a nickel layer and a gold-plated layer. The thickness of the nickel layer is t4, 3um≤t4≤7um.

8. A power module heat dissipation module, characterized in that: The power module heat dissipation module includes: heat sink; power components; and A heat-conducting medium, the heat-conducting medium comprising a first connecting layer, a second connecting layer, and a ceramic substrate according to any one of claims 1 to 7; the first connecting layer is arranged close to the first copper cladding layer on a side facing the ceramic substrate, and the first connecting layer is connected to the power element on a side facing away from the ceramic substrate; the second connecting layer is arranged close to the second copper cladding layer on a side facing the ceramic substrate, and the second connecting layer is connected to the heat sink on a side facing away from the ceramic substrate.

9. The power module heat dissipation module according to claim 8, characterized in that: The first connecting layer is a welding layer or an adhesive layer; and The second connection layer is a welding layer or an adhesive layer.

10. The power module heat dissipation module according to claim 9, characterized in that: The first connection layer is the adhesive layer, and the second connection layer is the welding layer.

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