Manufacturing method of double-sided conduction ceramic copper-clad plate

Abstract

The invention relates to the field of ceramic copper-clad plates, in particular to a manufacturing method of a double-sided conducting ceramic copper-clad plate for improving adhesive force between a copper sheet and a ceramic substrate, which comprises the following steps of: a, drilling a hole on the ceramic substrate to obtain a ceramic substrate hole, and processing burrs on the surface of the ceramic substrate hole which is of a through hole structure; b, the surface of the ceramic substrate obtained in the step a is cleaned, then holes of the ceramic substrate are filled with hole filling slurry, and the component of the hole filling slurry comprises Cu; c, the front face and the back face of the ceramic substrate are coated with brazing filler metal, the brazing filler metal is dried, and the brazing filler metal comprises Cu; and d, cleaning the copper sheets, respectively arranging the copper sheets on the brazing materials on the front surface and the back surface of the ceramic substrate, and then completing vacuum brazing to obtain the double-sided conduction copper-clad plate. The method is particularly suitable for the manufacturing process of the double-sided conduction ceramic copper-clad plate.

Description

Technical Field

[0001] This invention relates to the field of ceramic copper-clad laminates, and more particularly to a method for manufacturing a double-sided conductive ceramic copper-clad laminate. Background Technology

[0002] Ceramic-clad copper laminates are composite substrates in which copper layers are bonded to a ceramic substrate (such as alumina or aluminum nitride) at high temperatures. They possess high thermal conductivity, excellent electrical insulation, and strong adhesion. Double-sided conductive ceramic-clad copper laminates are special substrates with copper layers bonded to both sides of the ceramic substrate. They achieve double-sided circuit conduction through vertical interconnection, combining high thermal conductivity and electrical performance.

[0003] In existing processes, the main steps to achieve bonding between the copper layer and the ceramic substrate are: first, depositing a copper seed layer on the ceramic surface using magnetron sputtering; then forming circuit patterns through photolithography and development; next, increasing the copper layer thickness (typically 10-100 μm) through electroplating or electroless plating; and finally, removing the photoresist to complete the fabrication. In these processes, the bonding strength between the copper layer and the ceramic substrate is relatively low. Insufficient bonding strength can easily lead to delamination and peeling between the copper layer and the ceramic substrate. This delamination and peeling are caused by the large difference in the coefficients of thermal expansion between the copper layer and the ceramic substrate. This is especially true for double-sided conductive ceramic-clad laminates, where copper layers are present on both the front and back of the ceramic substrate. After repeated thermal cycling, double-sided conductive ceramic-clad laminates experience thermal stress failure, resulting in insufficient bonding strength and decreased adhesion between the copper layer and the ceramic substrate, ultimately leading to copper layer peeling. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for manufacturing a double-sided conductive ceramic copper-clad laminate that improves the adhesion between the copper foil and the ceramic substrate.

[0005] The technical solution adopted by this invention to solve its technical problem is: a method for manufacturing a double-sided conductive ceramic copper-clad laminate, comprising the following steps: a. Drill holes in a ceramic substrate to obtain ceramic substrate holes, remove burrs from the surface of the ceramic substrate holes, and the ceramic substrate holes are through-hole structures. b. Perform surface cleaning on the ceramic substrate obtained in step a, and then fill the holes in the ceramic substrate with a filling slurry, the filling slurry comprising Cu. c. Apply solder to the front and back sides of a ceramic substrate and dry the solder, wherein the solder comprises Cu. d. Clean the copper sheets and place them onto the solder on the front and back sides of the ceramic substrate, respectively. Then, perform vacuum brazing to obtain a double-sided conductive copper-clad laminate.

[0006] Furthermore, in step a, the drilling method on the ceramic substrate is laser drilling, and the holes obtained by drilling the ceramic substrate include product holes and positioning mark holes.

[0007] Furthermore, in step b, the surface cleaning steps of the ceramic substrate are, in sequence, degreasing, acid washing, water washing, ultrasonic water washing, deionized water cleaning, and drying.

[0008] Furthermore, in step b, the viscosity of the pore-filling slurry ranges from 60 Pa·s to 120 Pa·s, and the solid content of the pore-filling slurry ranges from 70% to 85%.

[0009] Furthermore, in step d, the cleaning steps for the copper sheet are, in sequence, degreasing, micro-etching, water washing, acid washing, ultra-scanning cleaning, deionized water cleaning, and drying.

[0010] Furthermore, the material composition for the micro-etching step includes sulfuric acid and sodium persulfate, with a sulfuric acid concentration of 6% to 10%, sodium persulfate concentration of 40 g / L to 80 g / L, a solution temperature of 30°C to 40°C, and a cleaning method of spraying with a spraying pressure of 0.1 MPa to 0.3 MPa.

[0011] Furthermore, in step d, the vacuum degree of vacuum brazing is ≤10. -3 Pa, the brazing temperature range for vacuum brazing is 700℃ to 1000℃.

[0012] Furthermore, in step a, the ceramic substrate is made of silicon nitride ceramic or aluminum nitride ceramic.

[0013] Furthermore, in step b, the filling paste in the holes of the ceramic substrate is filled by printing or scraping.

[0014] The beneficial effects of this invention are: I. A structure is created by forming through-holes in a ceramic substrate, filling the holes with a through-hole paste, and applying solder to both the front and back sides of the ceramic substrate. This allows copper sheets on the front and back sides of the ceramic substrate to be bonded together with the ceramic substrate through solder and through-hole paste. The resulting double-sided conductive copper-clad ceramic laminate has a void ratio of ≤1% and a peel strength of ≥10N / mm, resulting in more stable and reliable adhesion between the copper sheet and the ceramic substrate. Even after repeated thermal cycling, copper layer peeling will not occur.

[0015] 2. The method for filling the holes in the ceramic substrate with the filling paste is either printing or scraping. The process time of printing or scraping is significantly reduced compared to the existing electroplating filling process, thereby improving production efficiency.

[0016] Third, by optimizing the composition of the through-filling paste and the solder, that is, by including Cu in both the through-filling paste and the solder, a more stable bond can be formed between the copper foil and the through-filling paste and the solder, which further improves the adhesion between the copper foil and the ceramic substrate, thereby effectively eliminating the copper layer peeling phenomenon caused by repeated thermal cycling.

[0017] IV. The manufacturing method of this double-sided conductive ceramic copper-clad laminate can realize double-sided conductive copper cladding of silicon nitride, alumina, aluminum nitride and beryllium oxide ceramics, thus expanding the scope of influence of copper cladding process.

[0018] This invention is particularly applicable to the manufacturing process of double-sided conductive ceramic copper-clad laminates. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process flow of the present invention.

[0020] Figure 2 This is a schematic diagram showing the positional relationship between the ceramic substrate and the copper sheet of the present invention.

[0021] Figure 3 This is a schematic diagram of the ceramic substrate hole obtained after laser drilling according to the present invention.

[0022] Figure 4 yes Figure 3 A schematic diagram of a ceramic substrate after the holes have been filled with slurry.

[0023] The following are labeled in the diagram: ceramic substrate 1, ceramic substrate hole 2, solder layer 3, copper sheet 4. Detailed Implementation

[0024] The invention will be further described below with reference to the accompanying drawings.

[0025] like Figure 1 The diagram shows the manufacturing process of double-sided conductive ceramic copper-clad laminate, which mainly includes the following steps: a. Drill holes 2 in the ceramic substrate 1 to obtain ceramic substrate holes 2, and remove burrs from the surface of the ceramic substrate holes 2. The ceramic substrate holes 2 are through-hole structures. The drilling method on the ceramic substrate 1 is laser drilling. The resulting ceramic substrate holes 2 include product holes and positioning mark holes. The minimum diameter of the ceramic substrate holes 2 is 1 / 5 of the thickness of the ceramic substrate holes 2, and the diameter size of the ceramic substrate holes 2 is ±0.02mm. The specific drilling steps involve placing the ceramic substrate 1 on a dedicated drilling platform, and then scribing and drilling using a laser. When selecting laser energy, if CW mode is used, the laser energy is 80%, and the duty cycle is 15%-50%. If QW mode is used, the laser energy is 15%-35%, the duty cycle is 10%-40%, and the scribing speed is 10-50mm / s. For burr removal, a ceramic brush grinding method can be used, with a grinding speed of 0.3-0.8m / min and a ceramic brush current of 0.1-0.5A. The ceramic substrate 1 can be made of silicon nitride, aluminum nitride, aluminum oxide, beryllium oxide, or toughened aluminum oxide (ZTA).

[0026] b. Surface cleaning is performed on the ceramic substrate 1 obtained in step a. Then, a filling slurry is filled into the holes 2 of the ceramic substrate. The filling slurry contains Cu, specifically copper paste or electroplated copper filling paste. The ceramic surface cleaning can be performed using horizontal cleaning, with the following steps in sequence: degreasing, acid washing, water washing, ultrasonic water washing, deionized water washing, and drying. For degreasing, the concentration of the degreasing agent is 8% to 12%, the temperature is 30°C to 40°C, and the cleaning method is spraying at a pressure of 0.1 MPa to 0.3 MPa. For acid washing, the cleaning agent's main component is sulfuric acid, with a concentration of 8% to 12%, a temperature of 30°C to 40°C, and the cleaning method is spraying at a pressure of 0.1-0.3 MPa. For ultrasonic water washing, the frequency is 30 kHz to 100 kHz, the cleaning time is 2 min to 5 min, and the temperature is 30°C to 40°C. The ceramic DI water washing process uses deionized water with a resistivity ≥18.2 MΩ·cm, and the washing method is spraying at a pressure of 0.1 MPa to 0.3 MPa. The viscosity of the filling slurry ranges from 60 Pa·s to 120 Pa·s, and the solid content ranges from 70% to 85%. The filling slurry can be applied to the holes 2 of the ceramic substrate using either printing or scraping methods. When using printing, the screen mesh count is 80-150, the printing pressure is 0.1 MPa to 0.3 MPa, and the printing equipment uses a CCD vision system with a positioning accuracy within 30 μm. The drying temperature is 85±5℃.

[0027] c. Apply solder to the front and back sides of the ceramic substrate 1 to form solder layer 3, and then dry the solder. The solder composition includes Cu, and can be copper-zinc solder or copper-phosphorus solder. When applying the solder to the front and back sides of the ceramic substrate 1, conventional printing equipment is used, with a screen mesh count of 200-300, tension of 20±3N, and printing pressure of 0.2Mpa to 0.4Mpa. After printing on one side of the ceramic substrate 1, it is dried at a temperature of 100℃ to 150℃ for 10±2min. After one side of the ceramic substrate 1 is dried, the second side is printed and baked, thus completing the solder layer 3 on both the front and back sides.

[0028] d. Clean the copper sheet 4 and place it onto the solder on the front and back sides of the ceramic substrate 1, respectively. Vacuum brazing is then performed to obtain a double-sided conductive copper-clad laminate. The cleaning steps for the copper sheet 4 are as follows: degreasing, micro-etching, water washing, acid pickling, ultrasonic cleaning, deionized water cleaning, and drying. The degreasing agent used for cleaning the copper sheet 4 has a concentration of 8% to 12%, a temperature of 30°C to 40°C, and is applied by spraying at a pressure of 0.1 MPa to 0.3 MPa. The micro-etching material for the copper sheet 4 consists of sulfuric acid and sodium persulfate, with a sulfuric acid concentration of 6% to 10% and a sodium persulfate concentration of 40 g / L to 80 g / L. The solution temperature is 30°C to 40°C, and the cleaning method is spraying at a pressure of 0.1 MPa to 0.3 MPa. The pickling material for copper sheet 4 is mainly sulfuric acid, with a concentration of 8% to 12%, at a temperature of 30℃ to 40℃, using a spray cleaning method with a spray pressure of 0.1 MPa to 0.3 MPa. The water washing of copper sheet 4 is DI water washing (deionized water) with a resistivity ≥18.2 MΩ·cm, also using a spray cleaning method with a spray pressure of 0.1 MPa to 0.3 MPa. The dry drying of copper sheet 4 is done with hot air at a temperature ≥85℃. The vacuum degree for vacuum brazing is ≤10. -3 The brazing temperature range for vacuum brazing is 700-1000℃. A vacuum level ≤10 Pa can be achieved using a combination of rotary vane pumps, Roots pumps, and diffusion pumps. -3 Pa, where the diffusion pump operates at a temperature greater than 255°C.

[0029] Figure 2 The illustration shows an embodiment of a double-sided conductive ceramic copper-clad laminate, wherein a ceramic substrate 1 is located between two layers of copper sheets 4. A plurality of ceramic substrate holes 2 are uniformly arranged inside the ceramic substrate 1. These holes 2 are through-hole structures, meaning they penetrate the entire ceramic substrate 1. Electroplated copper-filling paste is disposed within the ceramic substrate holes 2, and copper-zinc solder is disposed on the upper and lower surfaces of the ceramic substrate 1, respectively. The copper sheets 4 and the ceramic substrate 1 are connected as a single unit by the electroplated copper-filling paste within the ceramic substrate holes 2 and the copper-zinc solder on the upper and lower surfaces of the ceramic substrate 1, forming a unified structure.

[0030] Figure 3 The image shown is of the uniformly arranged ceramic substrate holes 2 obtained after laser drilling of the ceramic substrate 1. Figure 4 The image shown represents the state after the copper plating paste has been filled into the hole 2 of the ceramic substrate.

[0031] The double-sided conductive ceramic-coated copper board prepared by this method has a void ratio of ≤1% and a peel strength of ≥10N / mm. Subsequently, samples of the double-sided conductive ceramic-coated copper board were made, and the conductivity of both sides was tested to be 100%, with a measured value of 0Ω for both sides.

[0032] Among them, the materials of the ceramic substrate 1 are selected as silicon nitride, aluminum oxide, aluminum nitride and beryllium oxide, respectively, and corresponding double-sided conductive ceramic copper-clad laminates are prepared. The peel strength test data of each are shown in Tables 1 to 4 below.

[0033] Table 1. Peel strength test data for silicon nitride double-sided conductive copper-clad laminates (N / mm) Table 2 Peel strength test data for alumina double-sided conductive copper-clad laminates (N / mm) Table 3 Peel strength test data for aluminum nitride double-sided conductive copper-clad laminates (N / mm) Table 4. Peel strength test data for beryllium oxide double-sided conductive copper clad laminate (N / mm) The double-sided conductive ceramic copper-clad laminate prepared by this method has a peel strength ≥10N / mm, and the adhesion between the copper foil and the ceramic substrate is significantly improved.

Claims

1. A method for manufacturing a double-sided conductive ceramic copper clad plate, characterized by, It comprises the following steps: a. Drilling holes on the ceramic substrate (1) to obtain ceramic substrate holes (2), and processing burrs on the surface of the ceramic substrate holes (2), wherein the ceramic substrate holes (2) are through-hole structures; b. Surface cleaning of the ceramic substrate (1) obtained in step a, and then filling the hole filling paste into the ceramic substrate holes (2), wherein the composition of the hole filling paste comprises Cu; c. Coating the brazing filler metal on the front and back surfaces of the ceramic substrate (1) to form a solder layer (3), and drying the brazing filler metal, wherein the composition of the brazing filler metal comprises Cu; d. Cleaning the copper sheet (4) and placing the copper sheet (4) on the brazing filler metal on the front and back surfaces of the ceramic substrate (1), respectively, and then completing vacuum brazing to obtain a double-sided conductive copper clad plate.

2. The method of claim 1, wherein the method further comprises: In step a, the drilling method on the ceramic substrate (1) is laser drilling, and the ceramic substrate holes (2) obtained by drilling include product holes and positioning mark holes.

3. The method of claim 1, wherein the method further comprises: In step b, the surface cleaning steps of the ceramic substrate (1) are oil removal, pickling, water washing, ultrasonic water washing, deionized water cleaning and drying in sequence.

4. The method of claim 3, wherein the method further comprises: In step b, the viscosity of the hole filling paste ranges from 60 Pa.s to 120 Pa.s, and the solid content of the hole filling paste ranges from 70% to 85%.

5. The method of claim 1 to 4, wherein the method is characterized by: In step d, the cleaning steps of the copper sheet (4) are oil removal, micro-etching, water washing, pickling, ultrasonic cleaning, deionized water cleaning and drying in sequence.

6. The method of claim 5, wherein the method further comprises: The material composition for realizing the micro-etching step comprises sulfuric acid and sodium persulfate, the concentration of sulfuric acid is 6% to 10%, the concentration of sodium persulfate is 40 g / L to 80 g / L, the temperature of the chemical solution is 30°C to 40°C, the cleaning method is spraying, and the spraying pressure is 0.1 MP to 0.3 MP.

7. The method of claim 1 to 4, wherein the method is characterized by: In step d, the vacuum degree of vacuum brazing is ≤10 -3 Pa, the brazing temperature range of vacuum brazing is 700℃ to 1000℃.

8. The method of claim 1 to 4, wherein the method is characterized by: In step a, the material of the ceramic substrate (1) is silicon nitride ceramic or aluminum nitride ceramic.

9. The method of claim 1 to 4, wherein the method is characterized by: In step b, the method for filling the hole filling paste into the ceramic substrate holes (2) is printing or blade coating.

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