Double-sided conduction AMB ceramic substrate and manufacturing method thereof

Abstract

The invention provides a double-sided conduction AMB ceramic substrate and a manufacturing method thereof, and belongs to the technical field of ceramic substrates for power modules. The manufacturing method comprises the following steps: punching holes in a ceramic substrate; filling conductive metal slurry into the holes by using a screen printing machine and sintering at high temperature; brazing materials are printed on the two faces of the ceramic; the copper layer and the ceramic layer are laminated and then subjected to vacuum brazing; manufacturing a circuit; etching the solder layer of the AMB line groove to expose the ceramic; performing surface treatment; laser cutting; and conducting test and inspection. Two-sided conduction is realized through metal slurry hole filling and a high-temperature sintering process, the problem that conduction of an upper copper layer and a lower copper layer of a traditional AMB ceramic substrate cannot be realized is solved, the assembling size of a power module is reduced, the three-dimensional integration requirement of a high-end module is met, meanwhile, the technological process is reasonable, and the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic substrate for power module, in particular to a double-sided conductive AMB ceramic substrate and a manufacturing method thereof. BACKGROUND

[0002] In recent years, the rapid development of power module products (such as IGBT and SiC power modules) has put forward higher requirements for ceramic substrate for chip bearing, and high-density integration has gradually become a new development trend. Active metal brazing (AMB) ceramic substrate is widely used in high-power scenarios due to its excellent thermal conductivity, insulation and reliability.

[0003] However, due to the structure and manufacturing process of traditional AMB ceramic substrate, direct electrical connection and conduction cannot be achieved between the copper layers on the upper and lower surfaces. This results in the need for additional leads or complex interconnection structures during assembly of the power module, increasing the volume of the module and limiting the improvement of product design and integration, making it difficult to meet the needs of high-end power modules for three-dimensional assembly and high-density integration.

[0004] In the prior art, there are some attempts to realize the upper and lower layer conduction of the ceramic substrate. For example, patent document CN114361301B discloses a method for interconnecting the upper and lower conductive layers of a ceramic substrate, which adopts through holes on the ceramic substrate and penetrates metal pieces that have been pretreated on the surface, and then performs sintering to realize interconnection. Patent document CN220915486U discloses an AMB ceramic copper-clad plate with through holes, and its conductive mechanism includes a copper column arranged in the ceramic substrate and two silver-copper solder pieces arranged on the upper and lower ends of the copper column and connected with the opposite copper layers.

[0005] The above-mentioned prior art solutions have some deficiencies. For example, the process of penetrating metal pieces or copper columns may be complex, requiring high processing precision of metal pieces and through holes, and there may be a risk of insufficient bonding strength or filling. The use of silver-copper solder pieces may also increase the complexity and cost of materials and processes.

[0006] Therefore, it is urgent to develop a double-sided conductive AMB ceramic substrate with high integration, simple and reliable process, and low cost, and a manufacturing method thereof. SUMMARY

[0007] The present application aims to overcome the deficiencies of the prior art and provide a double-sided conductive AMB ceramic substrate and a manufacturing method thereof. Through a special metal paste hole filling and sintering process, reliable conduction of the upper and lower copper layers is achieved while maintaining the advantages of the AMB process itself.

[0008] To achieve the above object, the technical scheme adopted by the present application is as follows: a double-sided conductive AMB ceramic substrate and a manufacturing method thereof, comprising a ceramic base, an upper copper layer and a lower copper layer formed on the upper surface and the lower surface of the ceramic base, and a conductive hole arranged in the ceramic base; the conductive hole is filled with a conductive metal paste subjected to high-temperature sintering, forming a conductive structure connecting the upper copper layer and the lower copper layer.

[0009] Preferably, the conductive metal paste is one of solder, copper paste or silver paste.

[0010] Preferably, the ceramic base and the upper copper layer, and the ceramic base and the lower copper layer are respectively combined through an active metal brazing material layer.

[0011] Preferably, the upper copper layer and / or the lower copper layer is provided with a circuit pattern formed by etching, and the ceramic base is exposed at the groove of the circuit pattern.

[0012] Preferably, a designated area of the upper copper layer and / or the lower copper layer is provided with a surface treatment layer, which is one of an oxidation-resistant layer, a chemical nickel-gold layer or a chemical silver layer.

[0013] On the other hand, the present application provides a manufacturing method of the above-mentioned double-sided conductive AMB ceramic substrate, comprising the following steps: S1: ceramic punching: punching a conductive hole on the ceramic base according to product design; S2: metal paste hole filling: filling the conductive metal paste into the conductive hole using a silk screen printer, and then performing high-temperature sintering to form a conductive structure; S3: brazing material printing: printing a layer of brazing material on both sides of the ceramic base after hole filling and sintering; S4: brazing: laminating the copper layer and the ceramic base printed with the brazing material, and then placing them into a vacuum brazing furnace for brazing to form a copper-clad ceramic substrate; S5: circuit manufacturing: manufacturing the required circuit pattern on the copper-clad ceramic substrate according to product design; S6: solder etching: etching away the solder layer at the AMB circuit groove using etching chemicals to expose the underlying ceramic; S7: surface treatment: performing surface treatment on the designated area of the substrate; S8: laser cutting: cutting the back surface of the substrate, and the cutting depth is 35%±5% of the thickness of the ceramic base; S9: conductive test: testing the resistance value of the upper and lower copper layers at the position of the conductive hole; S10: board splitting and inspection.

[0014] Preferably, in step S2, the temperature range of the high-temperature sintering is 700°C to 940°C, and the sintering time ranges from 60 minutes to 540 minutes.

[0015] Preferably, in step S4, the vacuum brazing is performed under a vacuum level of less than 0.01.

[0016] Preferably, in step S6, the etching solution is a special solution that can selectively etch the solder layer without causing significant damage to the copper layer and the ceramic substrate.

[0017] Preferably, in step S7, the surface treatment is one of anti-oxidation treatment, electroless nickel-gold plating, or electroless silver plating.

[0018] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: 1. Achieving double-sided conductivity and high-density integration: By using conductive metal paste to fill the vias and sintering at high temperature, the electrical connection between the upper and lower copper layers of the AMB ceramic substrate was successfully achieved, making it possible to 3D assembly and high-density integration of power modules and effectively reducing the module size.

[0019] 2. Simple and reliable process with high bonding strength: The metal paste is screen-printed to fill the holes. It has good fluidity and can fully fill the holes, forming a strong bond with the ceramic substrate and the copper layer that is subsequently brazed, resulting in high reliability.

[0020] 3. Reduced costs: Compared with copper pillars, silver-copper solder sheets and other solutions, the metal paste filling process is simpler, has relatively lower material costs, and is easier to mass-produce.

[0021] 4. Maintain the excellent performance of AMB substrate: While achieving double-sided conductivity, it retains the advantages of AMB ceramic substrate itself, such as high thermal conductivity, high insulation, and high reliability. Attached Figure Description

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings: Appendix Figure 1 This is a cross-sectional view of the double-sided conductive AMB ceramic substrate described in this invention.

[0023] The components are: 1. Ceramic substrate; 2. Upper copper layer; 3. Lower copper layer; 4. Through-hole; 5. Conductive structure; 6. Active metal brazing filler layer. Detailed Implementation

[0024] The application will be described in detail below with reference to the accompanying drawings and specific embodiments. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the application. These are within the scope of protection of the application. Embodiments

[0025] Appendix Figure 1 The double-sided conductive AMB ceramic substrate described in the application comprises a ceramic base 1, an upper copper layer 2 and a lower copper layer 3 bonded on the upper and lower surfaces of the ceramic base 1 by an active metal brazing material layer 6. The ceramic base 1 is provided with a conductive hole 4, and the conductive hole 4 is filled with a conductive structure 5 formed by high-temperature sintering of copper paste, which electrically connects the upper copper layer 2 and the lower copper layer 3. A specific circuit pattern is formed on the upper copper layer 2 by etching, and the solder layer has been etched away at the groove of the circuit pattern, exposing the underlying ceramic base 1. The surfaces of the upper copper layer 2 and the lower copper layer 3 are subjected to anti-oxidation surface treatment.

[0026] The manufacturing method mainly includes the following steps: 1. Ceramic hole punching: use a laser hole puncher to punch a conductive hole with a diameter of 0.2 mm on the aluminum nitride (AlN) ceramic substrate according to the design.

[0027] 2. Metal paste hole filling: use a high-precision silk screen printer to fill copper paste into the conductive hole, and after filling, send the ceramic substrate into a sintering furnace to sinter at 800°C in a vacuum environment for 120 minutes, so that the copper paste is firmly combined with the ceramic hole wall and forms a dense conductive path.

[0028] 3. Brazing material printing: uniformly coat a layer of Ti-Ag-Cu active metal brazing material on the upper and lower surfaces of the sintered ceramic substrate by silk screen printing.

[0029] 4. Brazing: align and stack the oxygen-free copper sheet with an oxygen content of less than 100 ppm and the ceramic substrate with printed brazing material, and place them into a vacuum brazing furnace to perform brazing under the conditions of a vacuum degree better than 1.0E-2 Pa and a maximum temperature of 830°C, and keep the temperature for 15 minutes to form an AMB copper-clad ceramic substrate.

[0030] 5. Circuit making: through exposure, development, etching and other patterning processes, the required circuit pattern is made on the copper layer of the copper-clad ceramic substrate.

[0031] 6. Solder etching: use a special acidic etching solution to selectively etch away the exposed brazing material layer at the circuit pattern groove, so that the ceramic at the bottom of the groove is completely exposed to meet the electrical insulation and heat dissipation requirements.

[0032] 7. Surface treatment: the substrate with the circuit is treated by electroless nickel plating and gold plating, the thickness of the nickel layer is 3-5 μm, and the thickness of the gold layer is 0.05-0.1 μm.

[0033] 8. Laser cutting: the back surface of the substrate is shallowly cut by using ultraviolet laser, the cutting depth is controlled to be 35%±5% of the total thickness of the ceramic substrate, so as to facilitate the subsequent plate splitting operation.

[0034] 9. Conduction test: the resistance value between the upper and lower copper layers at each conduction hole position is tested by using a multimeter or a low resistance tester, and it is ensured that the conduction is good (the resistance value is less than 10 mΩ).

[0035] 10. FQC and OQC: final quality inspection and shipment inspection are performed, and the substrate is packaged and shipped after passing the inspection. Embodiment

[0036] The difference between the embodiment and embodiment 1 is that the metal paste used for filling holes in step S2 is silver paste, the sintering temperature is 750°C, and the sintering time is 180 minutes. The surface treatment in step S7 is chemical silver plating.

[0037] The double-sided conduction AMB ceramic substrate prepared by the above embodiment successfully realizes low-resistance conduction of the upper and lower copper layers, and the conduction resistance is less than 10 mΩ. The substrate has good heat conductivity and insulation, and meets the requirements of high-power density power modules on the carrier substrate. At the same time, the manufacturing process is stable and reliable, and is suitable for large-scale production.

[0038] The above describes only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art, according to the technical solution and the inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, should be covered within the protection scope of the present application.

Claims

1. A double-sided conducting AMB ceramic substrate, comprising a ceramic base (1), an upper copper layer (2) and a lower copper layer (3) formed on the upper surface and the lower surface of the ceramic base (1), and a conducting hole (4) arranged in the ceramic base (1); characterized in that, The through hole (4) is filled with conductive metal paste (5) sintered at high temperature to form a conductive structure connecting the upper copper layer (2) and the lower copper layer (3).

2. The double-sided conducting AMB ceramic substrate of claim 1, wherein: The conductive metal paste (5) is one of solder, copper paste or silver paste.

3. The double-sided conducting AMB ceramic substrate of claim 1, wherein: The ceramic substrate (1) and the upper copper layer (2) and the ceramic substrate (1) and the lower copper layer (3) are respectively combined by an active metal brazing filler layer (6).

4. The double-sided conducting AMB ceramic substrate of claim 1, wherein: The upper copper layer (2) and / or the lower copper layer (3) is provided with a circuit pattern formed by etching, and the ceramic substrate (1) is exposed at the groove of the circuit pattern.

5. The double-sided conducting AMB ceramic substrate of claim 1, wherein: The specified area of the upper copper layer (2) and / or the lower copper layer (3) is provided with a surface treatment layer, which is one of an oxidation-resistant layer, a chemical nickel-gold layer or a chemical silver layer.

6. The method of claim 1-5, wherein: The method comprises the following steps: S1: ceramic punching: punching through holes on the ceramic substrate according to product design; S2: metal paste hole filling: filling conductive metal paste into the through holes using a screen printer, and then high-temperature sintering to form a conductive structure; S3: brazing filler printing: printing a layer of brazing filler on both sides of the ceramic substrate after hole filling and sintering; S4: brazing: laminating the copper layer and the ceramic substrate printed with brazing filler, and then placing it in a vacuum brazing furnace for brazing to form a copper-clad ceramic substrate; S5: circuit making: making the required circuit pattern on the copper-clad ceramic substrate according to product design; S6: solder etching: using etching chemicals to etch away the solder layer at the AMB circuit groove to expose the underlying ceramic; S7: surface treatment: surface treatment on the specified area of the substrate; S8: laser cutting: cutting the back of the substrate, the cutting depth is 35%±5% of the thickness of the ceramic substrate; S9: conduction test: test the resistance value of the upper and lower copper layers at the through hole position; S10: board splitting and inspection.

7. The method of claim 1, wherein: In step S2, the high-temperature sintering temperature ranges from 700°C to 940°C, and the sintering time ranges from 60 minutes to 540 minutes.

8. The method of claim 1, wherein: In step S4, the vacuum brazing is carried out under the condition that the vacuum degree is less than 0.

01.

9. The method of claim 1, wherein: In step S6, the etching chemicals are special chemicals that can selectively etch the solder layer without causing significant damage to the copper layer and the ceramic substrate.

10. The method of claim 1, wherein: In step S7, the surface treatment is one of oxidation-resistant treatment, chemical nickel-gold plating or chemical silver plating.

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