Multilayer ceramic substrate manufacturing method and multilayer ceramic substrate

Abstract

The invention discloses a multi-layer ceramic substrate manufacturing method and a multi-layer ceramic substrate, and relates to the field of ceramic substrate preparation, the multi-layer ceramic substrate comprises a second ceramic and a first ceramic, the top and the bottom of the second ceramic are coated with an L2 copper layer and an L3 copper layer through one of AMB and DBC, the top of the first ceramic is covered with an L1 copper layer through one of AMB and DBC, a copper column is inserted into the top of the first ceramic, active brazing materials are arranged on the top of the L1 copper layer in a silk-screen mode, and the active brazing materials are connected with the first ceramic through brazing. According to the manufacturing method of the multilayer ceramic substrate and the multilayer ceramic substrate, high-reliability multilayer wiring and interlayer conduction processes of a power module can be realized, so that a product can have high power density, is integrally miniaturized and integrated, and can optimize the structure so as to reduce generation of EMC (Electro Magnetic Compatibility), and the transmission distance between a signal line and a chip is reduced; and the stray inductance and the redundant capacitance are greatly reduced.

Description

Technical Field

[0001] The invention relates to the field of preparation of ceramic substrates, and in particular to a method for preparing a multi-layer ceramic substrate and a multi-layer ceramic substrate. Background Art

[0002] In recent years, power semiconductor devices have been gradually applied to various electronic systems, especially in the fields of new energy vehicles, 5G communications, rail transit, photovoltaic and wind power generation, where the performance requirements for power semiconductor devices are getting higher and higher, including high temperature resistance, high voltage resistance, high frequency, high power density, etc. Thick copper ceramic substrates have become ideal materials for power semiconductor packaging due to their excellent current carrying capacity, thermal conductivity, electrical insulation, mechanical strength and chemical stability. Thick copper ceramic substrates have DBC and AMB processes. Compared with direct bonded copper substrates, the bonding strength between the copper layer and the ceramic substrate of AMB ceramic substrates is very high, thanks to the use of active metal solder, which can provide stronger metal-ceramic bonding. This strong bonding force improves the structural integrity and durability of the substrate, enabling it to maintain stable performance under harsh working conditions.

[0003] Due to the special structure of traditional thick copper ceramics, the upper and lower layers of the circuits are not designed to be conductive. The copper on the top layer is used for electrical connection of the circuits, and the copper on the bottom layer is used for structural symmetry and welding with the bottom. For miniaturized integrated spaces that require multi-layer wiring, ceramic boards with inter-layer conductivity cannot be met by current technical solutions. Among them, the PTH process cannot meet the requirements of large currents due to its small cross-sectional area. In addition, the external via plug metal slurry process has poor conductivity, a large difference in CTE with ceramics, and is prone to cracking and poor reliability, which cannot meet the application of power modules.

[0004] Therefore, it is necessary to propose a method for manufacturing a multilayer ceramic substrate and a multilayer ceramic substrate to solve the above problems. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for manufacturing a multi-layer ceramic substrate and a multi-layer ceramic substrate, which can effectively solve the problems in the background technology.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for manufacturing a multilayer ceramic substrate comprises the following steps:

[0008] S1: using either AMB or DBC to perform double-sided copper coating on the second ceramic;

[0009] S2: copper-cladding the first ceramic on one side by one of AMB and DBC, the copper layer is marked as L1, the L1 copper layer is cut into a suitable size by laser, and a window is opened in the first ceramic by laser;

[0010] S3: Screen print active brazing material on the L2 copper layer;

[0011] S4: Insert the copper column to the position of the window in S2;

[0012] S5: bonding the second ceramic, the active brazing material and the first ceramic, and brazing them, thereby completing the preparation of the multilayer ceramic substrate.

[0013] Preferably, in S1, copper-cladding the second ceramic on both sides by AMB method comprises the following steps:

[0014] S101: preparing two copper layers, which are respectively recorded as L2 and L3, screen-printing the L2 copper layer and the L3 copper layer on the top and bottom of the second ceramic by means of active brazing material, and treating the surfaces of the L2 copper layer and the L3 copper layer, including grinding and cleaning, until oxides and impurities on the surfaces are removed;

[0015] S102: hot pressing a positive photolithography dry film on the surface of the L2 copper layer and the L3 copper layer, wherein the hot pressing temperature is 55-65° C., the hot pressing pressure is 0.35-0.45 MPa, and the hot pressing rate is 1.4-1.5 m / min;

[0016] S103: Perform a one-time exposure and development process on the hot-pressed positive photolithography dry film on the surface of the L2 copper layer and the L3 copper layer to transfer the circuit pattern to the surface of the copper layer on this side. The exposure energy is 100-1500mJ / cm 2 , exposure time 1-2min, developer is one of sodium carbonate, potassium carbonate, and 30°C aqueous solution with a concentration of 0.8-1.2wt%;

[0017] S104: using a mixed solution of cupric chloride and hydrochloric acid to etch the L2 copper layer and the L3 copper layer to the active brazing material, the cupric chloride concentration is 120-150 g / L, the hydrochloric acid concentration is 1.8-2.5 mol / L, the etching temperature is 20-35° C., and the etching time is 3-30 min;

[0018] S105: etching the active solder with an acid etching solution, wherein the acid etching solution comprises 300-500 g / L ferric chloride, 2-3 mol / L hydrochloric acid, 10-30 g / L sodium hypochlorite, and 0.05-0.10 g / L benzotriazole;

[0019] S106: performing secondary exposure and development treatment on the positive photoresist dry film on the surface of the L2 copper layer and the L3 copper layer on the side where the circuit pattern is printed, transferring the required surface treatment pattern to the surface of the copper layer on this side, and removing the positive photoresist dry film on the surface of the copper layer on the other side using a developer;

[0020] S107: performing surface treatment on the second ceramic after the secondary exposure and development treatment, including but not limited to gold plating, nickel plating, and silver plating;

[0021] S108: Use liquid to remove the residual positive photolithography dry film on the surface, and after testing it, including appearance inspection, size measurement, and electrical performance test, the AMB double-sided copper-clad second ceramic can be obtained.

[0022] Preferably, in S1, copper coating the second ceramic on both sides by DBC method comprises the following steps:

[0023] S109: cleaning and surface treating the second ceramic to ensure the flatness and cleanliness of the surface of the second ceramic;

[0024] S110: According to design requirements, an L2 copper layer and an L3 copper layer of a required shape and size are manufactured, and the L2 copper layer and the L3 copper layer are manufactured by one of electrolysis, rolling, and sputtering;

[0025] S111: evenly coating active brazing material on the surface of the second ceramic and one side of the L2 copper layer and the L3 copper layer to improve the quality and reliability of welding;

[0026] S112: accurately positioning the L2 copper layer and the L3 copper layer on the second ceramic, and ensuring good adhesion between the L2 copper layer and the L3 copper layer and the second ceramic;

[0027] S113: placing the positioned L2 copper layer, L3 copper layer and the second ceramic into a high temperature furnace for welding;

[0028] S114: After the welding is completed, the second ceramic is taken out from the high temperature furnace and cooled. After cooling, the second ceramic is cleaned with deionized water;

[0029] S115: Perform quality inspection on the second ceramic with double-sided copper cladding, including appearance inspection, dimension measurement, and electrical performance test, to obtain the second ceramic with double-sided copper cladding using DBC.

[0030] Preferably, in S2, the first ceramic is subjected to single-sided coating treatment in a manner similar to S1.

[0031] A multilayer ceramic substrate comprises a second ceramic and a first ceramic, characterized in that: the top and bottom of the second ceramic are covered with L2 copper layers and L3 copper layers by one of AMB and DBC, the top of the first ceramic is covered with L1 copper layer by one of AMB and DBC, a copper column is inserted into the top of the first ceramic, the top of the L1 copper layer is screen-printed with active brazing material, and the active brazing material is connected to the first ceramic by brazing.

[0032] Compared with the prior art, the present invention provides a method for manufacturing a multi-layer ceramic substrate and a multi-layer ceramic substrate, which have the following beneficial effects:

[0033] The multi-layer ceramic substrate manufacturing method and the multi-layer ceramic substrate can realize high-reliability multi-layer wiring of the power module and inter-layer conduction process, so that the product can have high power density, and at the same time, the overall miniaturization and integration can be optimized to reduce the generation of EMC, and the transmission distance between the signal line and the chip is reduced, the inductance and redundant capacitance are greatly reduced, and the generation of signal noise is reduced. It can be effectively applied to the flip chip packaging process, and the WireBonding and thermal and electrical separation are eliminated, which can effectively improve the overall reliability.

[0034] The present invention adopts active metal brazing slurry brazing and its interconnection process, and utilizes the wetting principle of Ag-Cu-Ti active metal filler in ceramic connection to achieve good bonding between ceramic and metal, ceramic and ceramic, and metal and metal, based on which high reliability performance requirements can be achieved, including interlayer conduction: the ceramic at the conduction position is hollowed out, and the copper column penetrates the hollowed-out ceramic and the copper surface of the silk-screened active solder to achieve reliable connection through brazing; interlayer insulation: the circuit layer is insulated by the ceramic, and the ceramic silk-screen active solder and the copper layer are reliably connected by high-temperature brazing. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic structural diagram of a multilayer ceramic substrate of the present invention;

[0036] Figure 2 It is a structural schematic diagram of a ceramic substrate in the prior art;

[0037] Figure 3 It is a process step diagram of the present invention.

[0038] In the figure: 1, second ceramic; 2, first ceramic; 3, L3 copper layer; 4, L2 copper layer; 5, copper column; 6, L1 copper layer; 7, active brazing material;

[0039] Figure 3 In the figure, Cu-Via is a copper pillar; L1 is an L1 copper layer; L2 is an L2 copper layer; L3 is an L3 copper layer; ceramic 1 is a first ceramic; and ceramic 2 is a second ceramic. DETAILED DESCRIPTION

[0040] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0041] Embodiment 1:

[0042] like Figure 1 , Figure 3 As shown, a method for manufacturing a multilayer ceramic substrate includes the following steps:

[0043] S1: using one of AMB and DBC to perform double-sided copper coating on the second ceramic 1;

[0044] S2: One of AMB and DBC is used to perform single-sided copper coating on the first ceramic 2, the copper layer is recorded as L1, the L1 copper layer 6 is cut into a suitable size by laser, a window is opened on the first ceramic 2 by laser, and the first ceramic 2 is coated on one side by a method similar to S1;

[0045] S3: screen printing active brazing material 7 at 4 locations of the L2 copper layer;

[0046] S4: insert the copper pillar 5 to the position of the window opening in S2;

[0047] S5: Laminating the second ceramic 1, the active brazing material 7 and the first ceramic 2, and brazing them to complete the preparation of the multilayer ceramic substrate.

[0048] In S1, copper coating on both sides of the second ceramic 1 by AMB method includes the following steps:

[0049] S101: preparing two copper layers, denoted as L2 and L3, respectively, screen-printing the L2 copper layer 4 and the L3 copper layer 3 on the top and bottom of the second ceramic 1 through an active brazing material 7, and treating the surfaces of the L2 copper layer 4 and the L3 copper layer 3, including grinding and cleaning, until oxides and impurities on the surfaces are removed;

[0050] S102: hot pressing a positive photolithography dry film on the surface of the L2 copper layer 4 and the L3 copper layer 3, wherein the hot pressing temperature is 55-65° C., the hot pressing pressure is 0.35-0.45 MPa, and the hot pressing rate is 1.4-1.5 m / min;

[0051] S103: Perform a first exposure and development process on the hot-pressed positive photolithography dry film on the surface of the L2 copper layer 4 and the L3 copper layer 3 to transfer the circuit pattern to the surface of the copper layer on this side. The exposure energy is 100-1500mJ / cm 2 , exposure time 1-2min, developer is one of sodium carbonate, potassium carbonate, and 30°C aqueous solution with a concentration of 0.8-1.2wt%;

[0052] S104: using a mixed solution of cupric chloride and hydrochloric acid to etch the L2 copper layer 4 and the L3 copper layer 3 to the active brazing material 7, the cupric chloride concentration is 120-150 g / L, the hydrochloric acid concentration is 1.8-2.5 mol / L, the etching temperature is 20-35° C., and the etching time is 3-30 min;

[0053] S105: etching the active solder 7 with an acidic etching solution, wherein the acidic etching solution comprises 300-500 g / L ferric chloride, 2-3 mol / L hydrochloric acid, 10-30 g / L sodium hypochlorite, and 0.05-0.10 g / L benzotriazole;

[0054] S106: performing secondary exposure and development treatment on the positive photoresist dry film on the surface of the L2 copper layer 4 and the L3 copper layer 3 on the side printed with the circuit pattern, transferring the required surface treatment pattern to the surface of the copper layer on this side, and removing the positive photoresist dry film on the surface of the copper layer on the other side with a developer;

[0055] S107: performing surface treatment on the second ceramic 1 after the secondary exposure and development treatment, including but not limited to gold plating, nickel plating, and silver plating;

[0056] S108: using liquid to remove the residual positive photolithography dry film on the surface, and after testing it, including appearance inspection, dimension measurement, and electrical performance test, the AMB double-sided copper-clad second ceramic 1 can be obtained.

[0057] In S1, copper coating on both sides of the second ceramic 1 by DBC method includes the following steps:

[0058] S109: cleaning and surface treating the second ceramic 1 to ensure the flatness and cleanliness of the surface of the second ceramic 1;

[0059] S110: According to design requirements, an L2 copper layer 4 and an L3 copper layer 3 of a required shape and size are manufactured, and the L2 copper layer 4 and the L3 copper layer 3 are manufactured by one of electrolysis, rolling, and sputtering;

[0060] S111: evenly coating active brazing material 7 on the surface of the second ceramic 1 and one side of the L2 copper layer 4 and the L3 copper layer 3 to improve the quality and reliability of welding;

[0061] S112: accurately positioning the L2 copper layer 4 and the L3 copper layer 3 on the second ceramic 1, and ensuring good adhesion between the L2 copper layer 4 and the L3 copper layer 3 and the second ceramic 1;

[0062] S113: placing the positioned L2 copper layer 4, L3 copper layer 3 and the second ceramic 1 into a high temperature furnace for welding;

[0063] S114: After the welding is completed, the second ceramic 1 is taken out from the high temperature furnace and cooled. After cooling, the second ceramic 1 is cleaned with deionized water;

[0064] S115: Perform quality inspection on the second double-sided copper-clad ceramic 1, including appearance inspection, dimension measurement, and electrical performance test, to obtain the second double-sided copper-clad ceramic 1 using DBC.

[0065] Embodiment 2:

[0066] like Figure 1As shown, a multilayer ceramic substrate includes a second ceramic 1 and a first ceramic 2, the top and bottom of the second ceramic 1 are covered with L2 copper layers 4 and L3 copper layers 3 by one of AMB and DBC, the top of the first ceramic 2 is covered with L1 copper layer 6 by one of AMB and DBC, a copper column 5 is inserted into the top of the first ceramic 2, the top of the L1 copper layer 6 is screen-printed with active brazing material 7, and the active brazing material 7 is connected to the first ceramic 2 by brazing.

[0067] like Figure 2 As shown, the conventional ceramic substrate of the prior art is not designed to be conductive due to the particularity of the structure of the upper and lower layers of the circuit. The copper on the top layer is used for electrical connection of the circuit, and the copper on the bottom layer is used for structural symmetry and welding with the bottom. For miniaturized integrated space, multi-layer wiring is required, and ceramic boards with inter-layer conductivity cannot meet the requirements of the existing technical solutions.

[0068] It can realize high-reliability multi-layer wiring of power modules and inter-layer conduction technology, so that the product can have high power density. At the same time, it is overall miniaturized and integrated, and can optimize the structure to reduce the generation of EMC, and reduce the transmission distance between signal lines and chips, greatly reduce the inductance and redundant capacitance, and reduce the generation of signal noise. It can be effectively applied to flip chip packaging technology, and eliminates WireBonding and thermal and electrical separation, which can effectively improve the overall reliability;

[0069] The present invention adopts active metal brazing slurry brazing and its interconnection process, and utilizes the wetting principle of Ag-Cu-Ti active metal filler in ceramic connection to achieve good bonding between ceramic and metal, ceramic and ceramic, and metal and metal, based on which high reliability performance requirements can be achieved, including interlayer conduction: the ceramic at the conduction position is hollowed out, and the copper column 5 penetrates the hollowed-out ceramic and the copper surface of the active brazing material 7 to achieve reliable connection through brazing; interlayer insulation: the circuit layer is insulated by the ceramic, and the ceramic silk screen and the copper layer are reliably connected through high-temperature brazing.

[0070] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for manufacturing a multilayer ceramic substrate, characterized in that: The steps include: S1: using either AMB or DBC to perform double-sided copper coating on the second ceramic; S2: copper-cladding the first ceramic on one side by one of AMB and DBC, the copper layer is marked as L1, the L1 copper layer is cut into a suitable size by laser, and a window is opened in the first ceramic by laser; S3: Screen print active brazing material on the L2 copper layer; S4: Insert the copper column to the position of the window in S2; S5: bonding the second ceramic, the active brazing material and the first ceramic, and brazing them, thereby completing the preparation of the multilayer ceramic substrate.

2. The method for manufacturing a multilayer ceramic substrate according to claim 1, characterized in that: In S1, copper coating on both sides of the second ceramic by AMB method includes the following steps: S101: preparing two copper layers, which are respectively recorded as L2 and L3, screen-printing the L2 copper layer and the L3 copper layer on the top and bottom of the second ceramic by means of active brazing material, and treating the surfaces of the L2 copper layer and the L3 copper layer, including grinding and cleaning, until oxides and impurities on the surfaces are removed; S102: hot pressing a positive photolithography dry film on the surface of the L2 copper layer and the L3 copper layer, wherein the hot pressing temperature is 55-65° C., the hot pressing pressure is 0.35-0.45 MPa, and the hot pressing rate is 1.4-1.5 m / min; S103: Perform a one-time exposure and development process on the hot-pressed positive photolithography dry film on the surface of the L2 copper layer and the L3 copper layer to transfer the circuit pattern to the surface of the copper layer on this side. The exposure energy is 100-1500mJ / cm 2 , exposure time 1-2min, developer is one of sodium carbonate, potassium carbonate, and 30°C aqueous solution with a concentration of 0.8-1.2wt%; S104: using a mixed solution of cupric chloride and hydrochloric acid to etch the L2 copper layer and the L3 copper layer to the active brazing material, the cupric chloride concentration is 120-150 g / L, the hydrochloric acid concentration is 1.8-2.5 mol / L, the etching temperature is 20-35° C., and the etching time is 3-30 min; S105: etching the active solder with an acid etching solution, wherein the acid etching solution comprises 300-500 g / L ferric chloride, 2-3 mol / L hydrochloric acid, 10-30 g / L sodium hypochlorite, and 0.05-0.10 g / L benzotriazole; S106: performing secondary exposure and development treatment on the positive photoresist dry film on the surface of the L2 copper layer and the L3 copper layer on the side where the circuit pattern is printed, transferring the required surface treatment pattern to the surface of the copper layer on this side, and removing the positive photoresist dry film on the surface of the copper layer on the other side using a developer; S107: performing surface treatment on the second ceramic after the secondary exposure and development treatment, including but not limited to gold plating, nickel plating, and silver plating; S108: Use liquid to remove the residual positive photolithography dry film on the surface, and after testing it, including appearance inspection, size measurement, and electrical performance test, the AMB double-sided copper-clad second ceramic can be obtained.

3. The method for manufacturing a multilayer ceramic substrate according to claim 1, characterized in that: In S1, copper coating the second ceramic on both sides by DBC method includes the following steps: S109: cleaning and surface treating the second ceramic to ensure the flatness and cleanliness of the surface of the second ceramic; S110: According to design requirements, an L2 copper layer and an L3 copper layer of a required shape and size are manufactured, and the L2 copper layer and the L3 copper layer are manufactured by one of electrolysis, rolling, and sputtering; S111: evenly coating active brazing material on the surface of the second ceramic and one side of the L2 copper layer and the L3 copper layer to improve the quality and reliability of welding; S112: accurately positioning the L2 copper layer and the L3 copper layer on the second ceramic, and ensuring good adhesion between the L2 copper layer and the L3 copper layer and the second ceramic; S113: placing the positioned L2 copper layer, L3 copper layer and the second ceramic into a high temperature furnace for welding; S114: After the welding is completed, the second ceramic is taken out from the high temperature furnace and cooled. After cooling, the second ceramic is cleaned with deionized water; S115: Perform quality inspection on the second ceramic with double-sided copper cladding, including appearance inspection, dimension measurement, and electrical performance test, to obtain the second ceramic with double-sided copper cladding using DBC.

4. The method for manufacturing a multilayer ceramic substrate according to claim 1, characterized in that: In S2, the first ceramic is subjected to single-sided coating treatment in a manner similar to S1.

5. A multilayer ceramic substrate, using a multilayer ceramic substrate manufacturing method as claimed in claim 1-3, comprising a second ceramic and a first ceramic, characterized in that: The top and bottom of the second ceramic are covered with L2 copper layer and L3 copper layer by one of AMB and DBC, the top of the first ceramic is covered with L1 copper layer by one of AMB and DBC, a copper column is inserted into the top of the first ceramic, the top of the L1 copper layer is screen-printed with active brazing material, and the active brazing material is connected to the first ceramic by brazing.

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