Manufacturing method of ternary sputter coating brazing ceramic substrate

Abstract

The invention relates to a manufacturing method of a ternary sputter coating brazing ceramic substrate, and relates to the technical field of ceramic substrate manufacturing. The method comprises the following steps: removing foreign matters attached to the surface of a ceramic substrate by adopting an ultrasonic cleaning process, polishing the ceramic substrate by adopting abrasive paper, treating oxidation and smudginess on the surface of a copper sheet by adopting a chemical deoiling and pickling process, attaching a chemical-resistant adhesive tape to a single surface of the copper sheet by using a vacuum adhesive tape pasting machine, and carrying out browning treatment. Forming a copper complex on the surface layer of the exposed copper sheet; carrying out magnetron sputtering on 100-200nm titanium on the surface of the ceramic substrate to form a wetting layer, and sputtering 100nm titanium nitride as an active reaction layer; sputtering a 300-500nm copper layer on the titanium nitride substrate to form a compact seed layer; carrying out silk-screen printing on a low-titanium solder on the sputtered ceramic substrate, then baking, and carrying out silk-screen printing on a second surface and baking; and stacking the copper sheets and the ceramic substrate, and performing vacuum brazing or nitrogen environment brazing. The method has the effect of improving the problems that cavities and other undesirable phenomena are prone to occurring on the copper-ceramic bonding interface and the peel strength is low.

Description

Technical Field

[0001] The present application relates to the technical field of ceramic substrate manufacturing, and in particular to a method for manufacturing a ternary sputtering-coated brazed ceramic substrate. Background Art

[0002] Ceramic substrates play a connecting role in power module electronic packaging, that is, they have the function of internal and external heat dissipation, and also have the functions of electrical connection and rigid mechanical support. The key to its technical barrier lies in copper-ceramic bonding. Combined with the current development status of the industry, the mainstream is divided into three types: DBC, AMB, and DPC. Among them, the copper-ceramic bonding in AMB presents higher bonding strength and resistance to cold and hot cycles due to the intermediate reaction layer of the brazing material. Therefore, compared with the other two processes, it is more suitable for connectors or scenes with large current carrying and high heat dissipation requirements. In the AMB bonding process, due to the influence of the solder itself, the silk screen printing process, the number of stacked layers, and the brazing curve, the local area of ​​the substrate, especially the edge, has uneven reaction, which leads to the edge Poor voids greatly sacrifice the utilization rate of the substrate and need to be improved by considering multiple factors, resulting in low efficiency at the production site. Magnetron sputtering technology is now relatively mature and has a wide range of target materials. As a key process of DPC (direct copper plating), it sputters a seed layer on the surface of the substrate with good uniformity. According to the reliability requirements of the ceramic substrate, the metal seed layer should have good bonding strength with the ceramic substrate, excellent high-temperature stability and conductivity, and can achieve hole interconnection. The industry is currently developing a process that complements magnetron sputtering technology with active brazing technology to form a more reliable copper-clad ceramic substrate. However, there are still problems such as voids at the solder-copper and solder-ceramic bonding interfaces and low peeling strength, so there is room for improvement. Summary of the invention

[0003] In order to improve the problem of voids and low peeling strength at the copper-ceramic bonding interface, the present application provides a method for manufacturing a ternary sputtering-coated brazed ceramic substrate.

[0004] The present application provides a method for manufacturing a ternary sputtering-coated brazed ceramic substrate substrate using the following technical solution: A method for manufacturing a ternary sputtering coating brazing ceramic substrate substrate comprises the following steps: An ultrasonic cleaning process is used to remove foreign matter attached to the surface of the ceramic substrate, the ceramic substrate is polished with sandpaper, oxidation and dirt on the surface of the copper sheet are treated by a chemical degreasing pickling process, and a chemical-resistant tape is attached to one side of the copper sheet using a vacuum tape sticking machine for browning treatment, so that a copper complex is formed on the surface of the exposed copper sheet; A wetting layer is formed on the surface of the ceramic substrate by magnetron sputtering 100-200 nm titanium to form a reaction substrate, and 100 nm titanium nitride is sputtered as an active reaction layer; sputtering a 300-500 nm copper layer on the titanium nitride to form a dense seed layer; On the sputtered ceramic substrate, low titanium solder is screen-printed and then baked, and the second side is screen-printed and baked; Stack copper sheets and ceramic substrates and perform vacuum brazing or nitrogen brazing.

[0005] By adopting the above technical solution, the optimal main material of the seed layer is copper. However, due to the poor bonding between copper and ceramics, it cannot withstand subsequent extreme applications and is easily separated from the ceramic layer. Titanium, as an active metal, has good bonding with both copper and ceramics. In order to ensure reliable sputtering of the copper seed layer, the titanium nitride target is magnetron sputtered to generate a very thin brazing active reaction layer, and finally the copper film is sputtered to form a titanium / titanium nitride / copper ternary film system as a new AMB ceramic substrate seed layer; the pretreatment process cleans the surface of the copper sheet and browns one side. During the brazing process, the microscopic hairs on the browned surface form a concave and convex surface, which can be filled with non-Newtonian fluid solder paste as a mechanical anchor, which is helpful In order to improve the bonding strength between the copper sheet and the solder layer, a triple sputtering method is used to generate the wetting layer, active reaction layer and copper seed layer required for brazing on the surface of the ceramic substrate, so that the surface of the ceramic substrate can be formed and evenly distributed with particles of about 300-500nm in size to increase the reaction activity. At the same time, the sputtering process is more uniform than direct vacuum brazing, so that the residual stress of the final ceramic substrate is more uniform, avoiding the problem of poor reliability of the ceramic substrate due to stress concentration. The ceramic substrate is affected by the ternary sputtering coating, and the overall copper-ceramic bonding is good, there is no abnormal void in the scan, and the peeling strength consistent with AMB can be maintained.

[0006] Preferably, the sandpaper adopts a 4000 mesh specification.

[0007] By adopting the above technical solution, the surface of the ceramic substrate can be polished more efficiently using 4000-mesh sandpaper, thereby facilitating the subsequent triple sputtering.

[0008] Preferably, the thickness of the low-titanium solder is 10 μm.

[0009] By adopting the above technical solution, the subsequent brazing can be ensured to be carried out stably, thereby improving the production quality of the ceramic substrate.

[0010] Preferably, the baking is performed using low-titanium solder or silver-free solder.

[0011] By adopting the above technical solution, the wide application of solder can be improved, and the production of ceramic substrates can be facilitated.

[0012] Preferably, the temperature of the vacuum brazing or nitrogen environment brazing is 700-800°C.

[0013] By adopting the above technical solution, the solder can be stably sintered and formed at this temperature, thereby accelerating the overall efficiency of ceramic substrate production.

[0014] Preferably, the stacked copper sheets and ceramic substrates are subjected to vacuum brazing or nitrogen environment brazing, and further include: performing TC testing on the finished product, with the number of test cycles being 6000 times.

[0015] By adopting the above technical solution, the reliability and durability of the ceramic substrate can be effectively tested, thereby ensuring that the performance of the ceramic substrate can meet the production requirements.

[0016] In summary, the present application includes at least one of the following beneficial technical effects: 1. Clean the surface of the copper sheet and brown one side. During the brazing process, the microscopic fluff on the brown surface forms a concave-convex surface, which can be filled with non-Newtonian fluid solder paste as a mechanical anchor, which helps to improve the bonding strength between the copper sheet and the solder layer; 2. Using triple sputtering, the wetting layer, active reaction layer and copper seed layer required for brazing are generated on the surface of the ceramic substrate respectively, so that particles with a size of about 300-500nm can be formed and evenly distributed on the surface of the ceramic substrate to increase the reaction activity; 3. The sputtering process is more uniform than direct vacuum brazing, making the residual stress of the final ceramic substrate more uniform, avoiding the problem of poor reliability of the ceramic substrate due to stress concentration; 4. The ceramic substrate is affected by the ternary sputtering coating, the overall copper-ceramic bonding is good, and there is no abnormal cavity in the scan; 5. The present application uses a magnetron sputtering process to sputter a titanium base, titanium nitride and a copper layer on the surface of a ceramic substrate, and finally sintering it, thereby preparing a copper-clad ceramic substrate at a low cost and high efficiency, and has high production efficiency and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flow chart of a method for manufacturing a ternary sputtering-coated brazed ceramic substrate substrate in an embodiment of the present application. DETAILED DESCRIPTION

[0018] The following is combined with Figure 1 This application is described in further detail.

[0019] The present application embodiment discloses a method for manufacturing a ternary sputtering coating brazing ceramic substrate substrate. Figure 1 , including the following steps: S1: Pretreatment of copper and ceramic, using ultrasonic cleaning process to remove foreign matter attached to the surface of the ceramic substrate, grinding the ceramic substrate with sandpaper of 4000 mesh, using chemical degreasing and pickling process to treat oxidation and dirt on the surface of the copper sheet, using a vacuum tape machine to attach chemical-resistant tape on one side of the copper sheet, and browning treatment to form a copper complex on the surface of the exposed copper sheet, thereby enhancing the bonding ability.

[0020] S2: Form a ternary coating, use magnetron sputtering to form a wetting layer of 100-200nm titanium on the surface of the ceramic substrate to form a reaction base, and sputter 100nm titanium nitride as an active reaction layer to ensure the bonding strength between the metal layer and the ceramic surface.

[0021] S3: Sputter a 300-500nm copper layer on the titanium nitride to form a dense seed layer to ensure good conductivity and brazing reaction activity.

[0022] S4: On the sputtered ceramic substrate, low titanium solder or silver-free solder is screen-printed and then baked, and the second side is screen-printed and baked. The solder thickness is about 10μm. It can also be directly vacuum brazed and sintered without solder according to needs.

[0023] S5: Stack the copper sheets and ceramic substrates, and perform vacuum brazing or nitrogen environment brazing at a temperature of 700-800°C. After brazing, perform a TC test with 6000 test cycles.

[0024] The implementation principle of the embodiment of the present application is as follows: the optimal main material of the seed layer is copper, but due to the poor bonding between copper and ceramics, it cannot withstand subsequent extreme applications and is easy to separate from the ceramic layer. Titanium, as an active metal, has good bonding with both copper and ceramics. In order to ensure reliable sputtering of the copper seed layer, the titanium nitride target is magnetron sputtered to generate a very thin brazing active reaction layer, and finally the copper film is sputtered to form a titanium / titanium nitride / copper ternary film system as a novel AMB ceramic substrate seed layer; the pretreatment process cleans the surface of the copper sheet and browns one side. During the brazing process, the microscopic hairs on the browned surface form a concave-convex surface, which can be filled with non-Newtonian fluid solder paste as a mechanical anchor, which helps In order to improve the bonding strength between the copper sheet and the solder layer, a triple sputtering method is used to generate a wetting layer, an active reaction layer and a copper seed layer required for brazing on the surface of the ceramic substrate, respectively. This enables the surface of the ceramic substrate to be formed and evenly distributed with particles of about 300-500nm in size to increase the reaction activity. At the same time, the sputtering process is more uniform than direct vacuum brazing, making the residual stress of the final ceramic substrate more uniform, avoiding the problem of poor reliability of the ceramic substrate due to stress concentration. The ceramic substrate is affected by the ternary sputtering coating, and the overall copper-ceramic bonding is good. There is no abnormal void in the scan, and the peeling strength consistent with AMB can be maintained.

[0025] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for manufacturing a ternary sputtering coating brazing ceramic substrate substrate, characterized in that: The steps include: An ultrasonic cleaning process is used to remove foreign matter attached to the surface of the ceramic substrate, the ceramic substrate is polished with sandpaper, oxidation and dirt on the surface of the copper sheet are treated by a chemical degreasing pickling process, and a chemical-resistant tape is attached to one side of the copper sheet using a vacuum tape sticking machine for browning treatment, so that a copper complex is formed on the surface of the exposed copper sheet; A wetting layer is formed on the surface of the ceramic substrate by magnetron sputtering 100-200 nm titanium to form a reaction substrate, and 100 nm titanium nitride is sputtered as an active reaction layer; sputtering a 300-500 nm copper layer on the titanium nitride to form a dense seed layer; On the sputtered ceramic substrate, low titanium solder is screen-printed and then baked, and the second side is screen-printed and baked; Stack copper sheets and ceramic substrates and perform vacuum brazing or nitrogen brazing.

2. The method for manufacturing a ternary sputtering brazing ceramic substrate according to claim 1, characterized in that: The sandpaper adopts 4000 mesh specifications.

3. The method for manufacturing a ternary sputtering brazing ceramic substrate according to claim 1, characterized in that: The thickness of the low titanium solder is 10 μm.

4. The method for manufacturing a ternary sputtering brazing ceramic substrate according to claim 1, characterized in that: The baking adopts low titanium solder or silver-free solder.

5. The method for manufacturing a ternary sputtering brazing ceramic substrate according to claim 1, characterized in that: The temperature of the vacuum brazing or nitrogen environment brazing is 700-800°C.

6. The method for manufacturing a ternary sputtering brazing ceramic substrate according to claim 1, characterized in that: The stacked copper sheets and ceramic substrates are subjected to vacuum brazing or nitrogen environment brazing, and further include: performing TC testing on the finished product, with the number of test cycles being 6000 times.

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