A ceramic substrate adapted for SOT-227 packaged rectifier bridge products

Abstract

The application relates to an SOT-227 package rectifier bridge ceramic substrate, and belongs to the technical field of semiconductor packaging, which comprises a metal layer, the metal layer comprising a first front copper-clad area, a second front copper-clad area, a third front copper-clad area and a fourth front copper-clad area arranged at intervals on the front surface, and a back copper-clad area arranged on the back surface; a surface plating layer, which is arranged on the outer surface of the metal layer; and a ceramic layer, which is arranged above the first front copper-clad area, the second front copper-clad area, the third front copper-clad area and the fourth front copper-clad area on the front surface for connection, and below the back copper-clad area for connection. The substrate has good heat dissipation performance. The heat dissipation performance of the product is significantly improved by selecting the ceramic layer material and thickness. The substrate effectively relieves stress concentration problems and improves the reliability of the substrate through etching design of the metal layer.

Description

Technical Field

[0001] This application belongs to the field of semiconductor packaging technology and relates to a ceramic substrate for adapting to SOT-227 packaged rectifier bridges. Background Technology

[0002] SOT-227 packaged rectifier bridge products have wide applications, mainly in power supplies, battery charging and energy storage, industrial equipment, motor drives, and other fields. The SOT-227 packaged rectifier bridge product mainly consists of a copper substrate, copper electrodes, a ceramic substrate, chips, high-purity aluminum wire, and molding compound. The back of four diode chips are soldered onto the ceramic substrate, and the front of the chips are bonded to the electrode circuit of the ceramic substrate via high-purity aluminum wire, forming a full-bridge rectifier topology. Insulation of the copper substrate is achieved through the ceramic substrate, and the connected rectifier bridge circuit is insulated and sealed by the molding compound.

[0003] Traditional SOT-227 packaged rectifier bridges typically use FR4 epoxy fiberglass substrates. However, FR4 substrates are prone to deformation at high temperatures and have low thermal conductivity, resulting in poor heat dissipation and severely impacting the stability and lifespan of the rectifier bridge. Furthermore, the electrical insulation performance of FR4 substrates deteriorates significantly under high temperature and high humidity conditions, increasing safety risks. Therefore, there is an urgent need to design an SOT-227 packaged rectifier bridge to address the problems existing in the current technology. Utility Model Content

[0004] To solve the above problems, the technical solution adopted in this application is: A ceramic substrate adapted to SOT-227 packaged rectifier bridge products includes: a metal layer, the metal layer including a first front copper-clad area, a second front copper-clad area, a third front copper-clad area and a fourth front copper-clad area disposed on the front side and a back copper-clad area disposed on the back side; A surface coating, wherein the surface coating is applied to the outer surface of the metal layer; A ceramic layer, the upper part of which is used to connect the first front copper-clad area, the second front copper-clad area, the third front copper-clad area and the fourth front copper-clad area, and the lower part of which is used to connect the back copper-clad area.

[0005] Furthermore, the ceramic layer is made of aluminum nitride ceramic.

[0006] Furthermore, the thickness of the ceramic layer is 0.38±0.05mm.

[0007] Furthermore, the minimum line spacing width of the etching channels between the first front copper-clad area, the second front copper-clad area, the third front copper-clad area, and the fourth front copper-clad area is 0.5±0.1mm.

[0008] Furthermore, the metal layer is a copper layer.

[0009] Furthermore, the thickness of the metal layer is 0.3±0.05mm.

[0010] Furthermore, the surface coating is a nickel plating.

[0011] Furthermore, the thickness of the surface coating is 2–8 μm, and the surface roughness of the surface coating is ≤1 μm.

[0012] Compared with the prior art, the beneficial effects of this application are as follows: This application provides a ceramic substrate adapted to SOT-227 packaged rectifier bridge products. The substrate of this application has good heat dissipation performance. By selecting the ceramic layer material and thickness, the heat dissipation performance of the product is significantly improved. The substrate of this application effectively alleviates the stress concentration problem and improves the reliability of the substrate through the etching design of the metal layer. Attached Figure Description

[0013] Figure 1 This is a front view of the substrate of this application; Figure 2 This is a schematic diagram of the back side of the substrate of this application; Figure 3 This is a side view of the substrate of this application; Figure 4 This is a three-dimensional structural diagram of the substrate of this application; Figure 5 Internal assembly diagram of an SOT-227 packaged rectifier bridge product; Figure 6 A three-dimensional structural diagram and circuit topology diagram of an SOT-227 packaged rectifier bridge product.

[0014] In the diagram: 1. First front copper cladding area, 2. Second front copper cladding area, 3. Third front copper cladding area, 4. Fourth front copper cladding area, 5. Back copper cladding area, 7. Lower left diode chip, 8. Lower right diode chip, 9. Upper right diode chip, 10. Upper left diode chip, 11. Lower left terminal, 12. Lower right terminal, 13. Upper right terminal, 14. Upper left terminal, 18. Second bonding of bonding wire, 19. Substrate, 20. Surface plating, 30. Ceramic layer, 40. Metal layer. Detailed Implementation

[0015] The present application will be further described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present application.

[0016] In the description of this utility model, it should be understood that the terms "left", "right", "up", "down", "symmetric", "parallel", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, rather than indicating a specific orientation or structure, and therefore should not be construed as a limitation of this utility model.

[0017] In this invention, unless otherwise expressly specified and limited, the first feature being "above" or "below" the second feature may include direct contact between the first and second features, or contact between the first and second features not being in direct contact but through another feature between them.

[0018] like Figures 1 to 6 As shown, this application provides a ceramic substrate adapted to SOT-227 packaged rectifier bridge products, comprising: a metal layer 40, the metal layer 40 including a first front copper-clad area 1, a second front copper-clad area 2, a third front copper-clad area 3, and a fourth front copper-clad area 4 spaced apart on the front side, and a back copper-clad area 5 disposed on the back side; a surface plating layer 20, the surface plating layer 20 being deposited on the outer surface of the metal layer 40; and a ceramic layer 30, the ceramic layer 30 being used to connect the first front copper-clad area 1, the second front copper-clad area 2, the third front copper-clad area 3, and the fourth front copper-clad area 4 on the front side, and used to connect the back copper-clad area 5 on the bottom side, the back copper-clad area 5 being connected to the ceramic layer 30 on the front side, and the entire substrate being soldered onto a substrate 19. In the embodiments of this application, the ceramic substrate structure is as follows: the substrate includes a ceramic layer 30, a metal layer 40, and a surface plating layer 20. The ceramic layer 30 is made of a high thermal conductivity material (aluminum nitride), the metal layer 40 is copper, and the surface plating layer 20 is nickel. For ceramic substrates, the requirements are: copper peel strength ≥10 N / mm, wire bonding strength ≥1000 N @ 300 μm aluminum wire, solder wettability >95%, surface roughness (Ra) ≤1 μm, insulation withstand voltage >6000 V @DC, warpage ≤0.5%, void ratio <1%, and void size <Φ1 mm. For ALN ceramic wafers, the requirements are: bulk density ≥3.25 g / cm³, surface roughness ≤0.5 μm, flexural strength ≥350 MPa, thermal conductivity ≥170 W / mK, and breakdown voltage DC ≥20 KV / mm. For copper-clad substrates (oxygen-free copper OFC), the requirements are: purity ≥99.99%, oxygen content ≤5 ppm, hardness (HV) 90-110, electrical conductivity ≥100, thermal conductivity ≥390 W / mK, and tensile strength 290-360 N / mm².

[0019] The layout design method of the substrate in this application is as follows: The front metal layer is mask-etched according to the design layout to form the rectifier bridge circuit pattern; the back metal layer is edge-etched to form a rectangular soldering area that is mirror-symmetrical to the pattern surface.

[0020] The ceramic layer of the substrate has a thickness of 0.38±0.05mm, the metal layer has a thickness of 0.3±0.05mm, and the nickel plating layer on the surface has a thickness of 2~8μm. The finished board is required to have a thickness of 0.98±0.1mm, an external dimension of 20±0.1mm in length, an external dimension of 19±0.1mm in width, and a minimum line spacing of 0.5±0.1mm.

[0021] The substrate preparation method of this application is as follows: The active metal brazing technology is used to ensure a reliable connection between the metal layer and the ceramic layer. The main processes include screen printing of brazing filler material, copper cladding, vacuum high-temperature sintering, exposure and development, circuit etching, chemical nickel plating, and laser cutting.

[0022] In this embodiment of the application, the first front copper-clad area 1 mainly involves the soldering of the lower left terminal 11, the soldering of the lower left diode chip 7, and the bonding wire bonding 18 above the upper left diode chip 10.

[0023] The second front copper-clad area 2 mainly involves the soldering of the lower right terminal 12, the soldering of the lower right diode chip 8, and the bonding wire bonding above the upper right diode chip 9.

[0024] The third front copper-clad area 3 mainly involves the soldering of the upper right terminal 13, the bonding wire bonding of the lower left diode chip 7, and the bonding wire bonding of the lower right diode chip 8.

[0025] The fourth front copper-clad area 4 mainly involves the soldering of the upper right and upper left terminals 14, the soldering of the upper right diode chip 9, and the soldering of the upper left diode chip 10.

[0026] The ceramic layer 30 is made of aluminum nitride ceramic.

[0027] The ceramic layer has a thickness of 0.38±0.05mm and a theoretical insulation value of ≥6600V.

[0028] The minimum line spacing of the etching channels between the first front copper clad area 1, the second front copper clad area 2, the third front copper clad area 3 and the fourth front copper clad area 4 is 0.5±0.1mm, and the theoretical insulation is ≥12000V.

[0029] The metal layer 40 is a copper layer.

[0030] The thickness of the metal layer 40 is 0.3 ± 0.05 mm.

[0031] The surface plating layer 20 is a nickel plating layer.

[0032] The thickness of the surface plating layer 20 is 2–8 μm, and the surface roughness Ra of the surface plating layer 20 is ≤1 μm. For the nickel plating layer, a thickness of 2–8 μm and a phosphorus content of 8% ± 2% are required.

[0033] The beneficial effects of this application are: Heat dissipation performance: By selecting the ceramic layer material and thickness, the heat dissipation performance of the product is significantly improved.

[0034] Stress distribution: The etching design of the metal layer effectively alleviates stress concentration problems and improves the reliability of the substrate.

[0035] Insulation performance: By selecting the ceramic layer material and thickness, the insulation requirements of the product are met.

[0036] This application significantly improves the heat dissipation performance, mechanical strength, and electrical reliability of the substrate by optimizing the material and thickness of the ceramic layer and precisely controlling the parameters of the metal layer and surface coating. This not only extends the service life of the rectifier bridge product but also improves its safety in high-temperature and high-humidity environments, bringing significant economic benefits and application value.

[0037] The process methods for radius corner size, etching factor, etc., which are not described in detail in this application, are all mature technologies and will not be elaborated further.

[0038] Of course, the above embodiments are not intended to limit this application, and this application is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this application should also fall within the protection scope of this application.

Claims

1. A ceramic substrate adapted to SOT-227 packaged rectifier bridge products, characterized in that: include: The metal layer (40) includes a first front copper-clad area (1), a second front copper-clad area (2), a third front copper-clad area (3) and a fourth front copper-clad area (4) disposed on the front side, and a back copper-clad area (5) disposed on the back side. A surface coating (20) is applied to the outer surface of the metal layer (40). The ceramic layer (30) is used to connect the first front copper clad area (1), the second front copper clad area (2), the third front copper clad area (3) and the fourth front copper clad area (4) on the top and the back copper clad area (5) on the bottom.

2. The ceramic substrate adapted to SOT-227 packaged rectifier bridge products according to claim 1, characterized in that: The ceramic layer (30) is made of aluminum nitride ceramic.

3. The ceramic substrate adapted to SOT-227 packaged rectifier bridge products according to claim 2, characterized in that: The thickness of the ceramic layer is 0.38 ± 0.05 mm.

4. The ceramic substrate adapted to SOT-227 packaged rectifier bridge products according to claim 1, characterized in that: The minimum line spacing width of the etching channel between the first front copper clad area (1), the second front copper clad area (2), the third front copper clad area (3) and the fourth front copper clad area (4) is 0.5±0.1mm.

5. A ceramic substrate adapted to SOT-227 packaged rectifier bridge products according to claim 1, characterized in that: The metal layer (40) is a copper layer.

6. A ceramic substrate adapted to SOT-227 packaged rectifier bridge products according to claim 5, characterized in that: The thickness of the metal layer (40) is 0.3±0.05mm.

7. A ceramic substrate adapted to SOT-227 packaged rectifier bridge products according to claim 1, characterized in that: The surface coating (20) is a nickel coating.

8. A ceramic substrate adapted to an SOT-227 packaged rectifier bridge product according to claim 7, characterized in that: The thickness of the surface coating (20) is 2 to 8 μm, and the surface roughness (Ra) of the surface coating (20) is ≤1 μm.

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