A method for preparing a high-precision multilayer ceramic substrate with high reliability

Abstract

The application discloses a kind of preparation methods of high-precision multilayer ceramic substrate of high reliability, it is related to multilayer ceramic substrate technical field;Specifically including the following steps: S1: ceramic micropore processing;S2: magnetron sputtering;S3: sputtering ceramic patterning;S4: silk printing hole filling;S5: foil sintering;S6: metal foil image etching and alignment silk printing;S7: multilayer ceramic substrate pre-lamination;S8: secondary sintering;S9: outer layer DPC fine line production;The application combines the advantages of AMB and DPC two processes, combines DPC process with multilayer board technology, realizes high-precision multilayer ceramic substrate with high wiring density, the reliability of the product of the application is higher, the cost is lower, can satisfy future high-density integrated circuit packaging demand.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a preparation method of high-precision multilayer ceramic substrate with high reliability. BACKGROUND

[0002] With the development of multi-chip packaging and micro-system packaging technology, the application of multilayer board is more and more widely, and the existing multilayer ceramic substrate is mainly prepared by high-temperature co-firing (HTCC) process or low-temperature co-firing (LTCC) process, but the heat conduction performance of the LTCC product limits its use in high-power packaging modules. The traditional HTCC preparation of multilayer ceramic substrate has great difficulty, high cost, and differences in sintering shrinkage between batches, so the consistency of the product is low. In addition, the metalization of multilayer board is usually realized by screen printing method, but the pattern precision of screen printing is limited, the flatness is poor, the microwave transmission loss is large, and the line width and line spacing are difficult to break through 30 μm. The ceramic thin film process (DPC) mainly uses photolithography, etching and deposition, etc., and has the advantages of no shrinkage and fine line. It can easily realize 20 μm line width and line spacing, meet the high-density wiring, and has high metalization flatness and small microwave transmission loss, but the wiring layer is limited, and the multilayer wiring is difficult. At present, there is no related report on the preparation of high-precision multilayer ceramic substrate based on DPC process.

[0003] In summary, in order to solve the above problems, it is of great significance to prepare a high-precision multilayer ceramic substrate with high reliability. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of high-precision multilayer ceramic substrate with high reliability to solve the problems in the prior art.

[0005] In the first aspect of the present application, a high-precision multilayer ceramic substrate with high reliability is provided, which has the following technical features: comprising a multilayer ceramic layer, an interlayer metal line layer, a ceramic internal via hole and a surface metallization layer.

[0006] Further, in the high-precision multilayer ceramic substrate with high reliability provided by the present application, the multilayer ceramic is aluminum nitride or silicon nitride ceramic, and the ceramic thickness is 0.1-0.5 mm.

[0007] Further, the interlayer metal line of the present application can be a metal foil, and the components of the foil include but are not limited to W, Mo, Nb, Ta, Cu and other metals.

[0008] Further, the application provides a high-reliability high-precision multilayer ceramic substrate, wherein the internal through hole of the ceramic is formed by laser equipment on the surface of the ceramic, the internal through hole is filled with conductive metal, the main components of the filling hole metal paste for the internal through hole include one or both of W and Mo, and further include one or more of Cu, Ti, Cr, Ni and the like; the through hole can be one or more of a through hole, a blind hole and a buried hole.

[0009] Further, the application provides a high-reliability high-precision multilayer ceramic substrate, wherein the surface metallization layer is prepared by a DPC process, and the surface metallization layer is interconnected with the interlayer metal layer through the internal through hole of the ceramic.

[0010] To achieve the above-mentioned purpose, the second aspect of the application provides the following technical scheme:

[0011] A preparation method of a high-reliability high-precision multilayer ceramic substrate, comprising the following steps:

[0012] S1: performing micro-hole processing on a ceramic sheet to form positioning holes and internal through holes; and cleaning to obtain a ceramic sheet A;

[0013] S2: sequentially performing ion bombardment cleaning and surface sputtering of a metal layer on the surface of the ceramic sheet A to obtain a single-sided ceramic sheet and a double-sided ceramic sheet;

[0014] S3: performing sputtering ceramic patterning on the metal layer of the single-sided ceramic sheet and the double-sided ceramic sheet to obtain a patterned single-sided ceramic sheet and a patterned double-sided ceramic sheet;

[0015] S4: performing alignment screen printing of the patterned single-sided ceramic sheet and the patterned double-sided ceramic sheet, drying, and correspondingly obtaining an outer ceramic sheet and an intermediate ceramic sheet A;

[0016] S5: attaching a metal foil to one side of part of the intermediate ceramic sheet A, high-temperature sintering and cooling; and obtaining a foil-attached intermediate ceramic sheet A;

[0017] S6: performing metal foil pattern etching on the surface of the foil-attached intermediate ceramic sheet A, and performing alignment screen printing of a medium paste; and obtaining an intermediate ceramic sheet B;

[0018] S7: aligning and mounting the outer ceramic sheet, the intermediate ceramic sheet A and the intermediate ceramic sheet B by using the positioning holes to form a laminated structure; and obtaining a pre-laminated multilayer ceramic substrate;

[0019] S8: performing secondary sintering and cooling on the pre-laminated multilayer ceramic substrate to obtain a basic multilayer ceramic substrate;

[0020] S9: polishing the surface of the basic multilayer ceramic substrate, and performing DPC fine line manufacturing to obtain a high-precision multilayer ceramic substrate.

[0021] More preferably, in step S7, the lamination structure of the pre-lamination multilayer ceramic substrate is as follows: the outermost layers of the multilayer ceramic substrate are provided with outer ceramic sheets; the middle part of the multilayer ceramic substrate is provided with middle ceramic sheet A in odd layers and middle ceramic sheet B in even layers; and the number of layers of the middle ceramic layer in the multilayer ceramic substrate is odd.

[0022] More preferably, in step S2, during the ion bombardment cleaning process, the specific process conditions are as follows: vacuum degree is 20-1200 Pa, argon pressure is 0.2-1 Pa, voltage is 0.6-0.8 KV, and cleaning time is 180-300 seconds.

[0023] In the sputtering process, the magnetic sputtering is used, and the specific process conditions are as follows: the vacuum degree in the furnace cavity is 10 -4 ~10 -3 Pa, the argon pressure is 0.2-1 Pa, the sputtering power is 15-25 KW, the voltage is 500-800 V, the time is 60-180 min, and the temperature is 200-300°C.

[0024] More preferably, in step S5, during the high-temperature sintering process, the specific process is as follows: the temperature is 900-1500°C, the holding time is 20-90 min, the vacuum degree in the furnace is <0.01 Pa, and the pressure is 10-30 Mpa.

[0025] In step S8, during the secondary sintering process, the specific process is as follows: the temperature is 900-1500°C, the holding time is 20-90 min, the vacuum degree in the furnace is <0.01 Pa, and the pressure is 10-30 Mpa.

[0026] More preferably, in step S2, the thickness of the metal layer is 0.5-5 μm; the metal layer includes an active metal layer and other metal layers, and the active metal layer is on the side close to the ceramic; the active metal layer includes one of titanium and zirconium; and the other metal layer includes one or more of copper, nickel, and silver.

[0027] In step S5, the metal foil includes one of tungsten foil, molybdenum foil, tungsten-molybdenum foil, molybdenum-copper foil, tungsten-copper foil, tantalum foil, and niobium foil, and the thickness is 5-30 μm.

[0028] In step S7, the medium slurry includes one of insulating slurry and functional slurry.

[0029] More preferably, in step S4, during the hole filling by aligning silk printing, the slurry used is metal slurry.

[0030] The metal paste comprises the following raw materials in parts by mass: 85-92 parts of metal powder, 8-15 parts of organic matter; the metal powder comprises non-melting metal powder and melting metal powder in a mass ratio of 16:3-4; the non-melting metal powder comprises one or more of tungsten powder, molybdenum powder and tungsten-molybdenum powder; the melting metal powder comprises one or more of copper powder, silver powder and nickel powder; and the organic matter is a terpene-4-ol system.

[0031] The terpene-4-ol system comprises the following raw materials in mass fractions: 60-85% of terpene-4-ol, 5-15% of ethyl cellulose, 2-4% of acrylic resin, 2-4% of hydrogenated castor oil, 2-6% of KH550, 2-5% of tributyl citrate and 0.5-1.5% of BYK-111.

[0032] The metal paste is different from existing paste on the market, and does not contain inorganic phase, oxide, glass phase and the like, and is dried by using an oven after ceramic hole filling is completed.

[0033] More preferably, the metal paste comprises the following raw materials in parts by mass: 85-92 parts of metal powder, 14-16 parts of water-based adhesive and 0.3-0.5 parts of defoamer RJ-6501; the metal powder comprises the following raw materials in parts by mass: 14-15 parts of silver-coated copper powder and 70-76 parts of tungsten powder.

[0034] More preferably, the water-based adhesive comprises the following raw materials in parts by mass: 13-14 parts of modified polyacrylic acid resin aqueous solution and 1-2 parts of hydroxyethyl cellulose.

[0035] More preferably, a preparation method of the modified polyacrylic acid resin aqueous solution comprises the following steps: (1) adding sodium dodecyl sulfonate and alkylphenol polyoxyethylene ether into deionized water and stirring uniformly, adding methyl methacrylate, butyl acrylate, acrylic acid and acrylamide and stirring uniformly at 150-160 r / min to obtain a monomer emulsion;

[0036] (2) adding the monomer emulsion and 0.1-0.2 parts of ammonium persulfate into a reaction kettle, stirring at 75-80℃ for 50-70 min, dropping the monomer emulsion and ammonium persulfate, controlling the dropping time to be 2-3 h, after dropping is completed, stirring at 85-90℃ for 1-1.5 h, adjusting the pH to 6-8, filtering to obtain a filtrate, diluting with water to a solid content of 60% to obtain the water-based polyacrylic acid resin aqueous solution;

[0037] (3) adding aminoferrocene into the water-based polyacrylic acid resin aqueous solution and stirring uniformly, adding an activator, stirring at 50-60℃ for 3-5 h to obtain the modified polyacrylic acid resin aqueous solution.

[0038] More preferably, the monomer emulsion comprises the following mass parts of raw materials: 2-3 parts of sodium dodecyl sulfonate, 1-2 parts of alkyl phenol polyoxyethylene ether, 40-45 parts of deionized water, 8-10 parts of acrylic acid, 2-4 parts of acrylamide;

[0039] The aqueous polyacrylic acid resin solution comprises the following mass parts of raw materials: 96-104 parts of monomer emulsion, 0.5-0.7 parts of ammonium persulfate;

[0040] The modified polyacrylic acid resin solution comprises the following mass parts of raw materials: 2-3 parts of aminoferrocene, 100 parts of the aqueous polyacrylic acid resin solution, and 1-2 parts of an activator.

[0041] Compared with the prior art, the application has the following beneficial effects:

[0042] (1) The multilayer ceramic substrate prepared by the application uses a high-performance biscuit, instead of a green biscuit used in traditional HTCC, and there is no problem of different shrinkage rates of different batches of HTCC, and the sintering shrinkage is negligible, resulting in high yield; compared with the generally thin thickness of the HTCC green body, the application can select appropriate number of layers and biscuit thickness according to product requirements, the range of biscuit selection is wide, and the number of layers can be appropriately reduced, thereby reducing the process difficulty and production cost.

[0043] (2) The connection between the layers of the multilayer ceramic substrate prepared by the application is based on the principle of active metal brazing, and the active metal brazing + metal foil mode makes the brazing layer between the ceramics continuous, uniform and dense, the combination is firm, and the air tightness is higher; the metal foil between the layers does not melt or shrink during the sintering process, so the controllability of the pattern resistance is high; in addition, when the biscuit is sintered at high temperature, the ceramic grains will grow synchronously, and the glass phase in the ceramic will soften at high temperature, and will flow viscously under the double action of external load, thereby reducing the porosity in the ceramic and reducing the defects of the ceramic, and improving the air tightness and reliability of the multilayer ceramic substrate.

[0044] (3) The pattern line of the multilayer ceramic substrate prepared by the application is made by a thin film etching process and a DPC process, and the pattern precision is higher and the wiring density is larger than that of the traditional HTCC screen printing, and it is more in line with the future demand for high-density integrated circuit packaging.

[0045] (4) The present invention also provides an aqueous metal slurry, which mainly includes an aqueous solution of an aqueous polyacrylic resin, and the solvent is water. The combination of the traditional pine alcohol system and metal powder is accompanied by strong volatilization of organic matter during the drying process, which will irritate the human body or the environment. The present invention can provide better adhesive properties without introducing low-melting-point metal or glass phase by preparing an aqueous polyacrylic resin, thereby improving conductivity. The present invention introduces acrylamide into the copolymerization during the preparation process, which helps to improve the wettability to ceramics and the dispersibility of the system. Furthermore, the present invention also grafts ferrocene into the aqueous polyacrylic resin. In the subsequent vacuum sintering process, organic matter can be used as a carbon source to promote carbon graphitization and improve the density and conductivity after sintering. At the same time, in the selection of metal powder, a combination of silver-coated copper and tungsten powder is selected: on the one hand, the copper is difficult to contact with the outside world after being coated, which helps to reduce copper oxidation; on the other hand, the introduction of a small amount of silver helps to further optimize conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a process flow chart of the present invention;

[0047] Figure 2 is a schematic cross-sectional view of the structure of a multilayer ceramic substrate according to Example 1 of the present invention;

[0048] Figure 3 is a schematic cross-sectional view of a single-layer structure according to Example 1 of the present invention;

[0049] in, Figure 2 Among them, 01, 03, and 05 are odd-numbered ceramic layers, 02 and 04 are even-numbered ceramic layers, and 06 is a fine circuit prepared by the DPC process on the surface of the multi-layer board; Figure 3 In the figure, 02 is a double-layer ceramic, 021 is a slurry-filled via hole, 022 is a metal foil etched pattern circuit, and 023 is a screen-printed dielectric slurry. DETAILED DESCRIPTION

[0050] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0051] It should be noted that the purchase manufacturer of all raw materials involved in the present application has no special restriction, and exemplary includes: aluminum nitride ceramic, thickness of 0.3 mm; tungsten powder, particle size of 5-10 μm; copper powder, particle size of 5-10 μm; silver-coated copper powder, silver content of 15 wt%, particle size of 5-10 μm, provided by Chengdu Huxiba 57 New Material Co., Ltd.; tungsten foil, thickness of 15 μm; methyl methacrylate, CAS number: 80-62-6; acrylic acid, CAS number: 79-10-7; acrylamide, CAS number: 79-06-1; aminoferrocene, CAS number: 1273-82-1.

[0052] In the following examples, parts are mass parts, and the above-mentioned and below-used raw materials are all commercially available.

[0053] Example 1: Preparation of high-precision multilayer ceramic substrate includes the following steps:

[0054] S1: A laser drilling device is used to drill aluminum nitride ceramic to form positioning holes and internal through holes; the drilled ceramic is cleaned to remove the micro-hole edge slag, and a ceramic sheet A is obtained;

[0055] S2: The surface of the ceramic sheet A is sequentially subjected to ion bombardment cleaning and magnetron sputtering deposition of a metal layer; the outermost two ceramic sheets are single-sided sputtered to obtain single-sided ceramic sheets; the rest are double-sided sputtered to obtain double-sided ceramic sheets; the sputtered metal layer is divided into two layers, a copper layer is sputtered first, and then a titanium layer is sputtered; the sputtering vacuum degree is 10 -4 Pa, the argon pressure is 0.2 Pa; the titanium target sputtering power is 8 KW, the sputtering time is 30 min; the copper target sputtering power is 15 KW, the sputtering time is 100 min, and the sputtering temperature is 240℃;

[0056] S3: Sputtering ceramic patterning treatment is performed on the metal layer of the single-sided ceramic sheet and the double-sided ceramic sheet: film pasting, exposure and development, and etching of fine line patterns; patterned single-sided ceramic sheets and patterned double-sided ceramic sheets are obtained;

[0057] S4: The patterned single-sided ceramic sheet and the patterned double-sided ceramic sheet are subjected to alignment screen printing of hole-filling metal paste, and are dried at a drying temperature of 120℃ for 15 min; corresponding outer ceramic sheets and intermediate ceramic sheets A are obtained;

[0058] S5: The intermediate ceramic sheets A located at double-numbered layers in the multilayer board are double-sidedly attached with metal foils, high-temperature sintering and cooling; the metal foil is a calendered tungsten foil; the sintering temperature is 1150℃, the holding time is 30 min, the furnace vacuum degree is <0.01 Pa, and the pressure is 10 Mpa; foil-attached intermediate ceramic sheets A are obtained;

[0059] S6: Etching the surface of the foil-coated intermediate ceramic sheet A with a metal foil pattern: exposing and developing the film to etch out the desired corresponding pattern; aligning and screen-printing the dielectric slurry: screen-printing the dielectric slurry in the gaps between the pattern lines and drying the dielectric slurry model 07HD290; drying at a temperature of 100°C for 15 minutes; obtaining the intermediate ceramic sheet B;

[0060] S7: aligning and installing the outer ceramic sheet, the middle ceramic sheet A, and the middle ceramic sheet B using the positioning holes to form a laminated structure: the outer ceramic sheets are arranged on both outermost surfaces of the multilayer ceramic substrate; the middle portion of the multilayer ceramic substrate is provided with the middle ceramic sheet A on the odd-numbered layers and the middle ceramic sheet B on the even-numbered layers; the number of the middle ceramic layers in the multilayer ceramic substrate is three; and a pre-laminated multilayer ceramic substrate is obtained;

[0061] S8: performing secondary sintering and cooling on the pre-laminated multilayer ceramic substrate; the sintering temperature is 1100° C., the holding time is 40 min, the vacuum degree in the furnace is less than 0.01 Pa, and the pressure is 15 MPa; thereby obtaining a basic multilayer ceramic substrate;

[0062] S9: Grinding and polishing the surface of the base multilayer ceramic substrate; preparing a high-density surface circuit on the multilayer ceramic substrate using a DPC process to obtain a high-precision multilayer ceramic substrate.

[0063] The metal slurry includes the following raw materials, calculated by mass: 89 parts of metal powder and 11 parts of organic matter; the metal powder includes tungsten powder and copper powder in a mass ratio of 16:3; and the organic matter is a terpineol system.

[0064] Example 2: Preparation of a high-precision multilayer ceramic substrate includes the following steps:

[0065] Step 1: Preparation of modified polyacrylic acid: (1) Add 2.5 parts of sodium lauryl sulfate and 1.5 parts of alkylphenol polyoxyethylene ether to 40 parts of deionized water and stir evenly, then add 50 parts of methyl methacrylate, 34 parts of butyl acrylate, 9 parts of acrylic acid, and 3 parts of acrylamide, and stir evenly at 150-160 r / min to obtain a monomer emulsion;

[0066] (2) adding 30 parts of monomer emulsion and 0.15 parts of ammonium persulfate to a reaction kettle, stirring at 80° C. for 60 minutes, adding 70 parts of monomer emulsion and 0.5 parts of ammonium persulfate dropwise, controlling the addition time to be 2.5 hours, stirring at 90° C. for 1.5 hours after the addition is completed, adjusting the pH to 7.5, filtering to obtain a filtrate, and diluting with water to a solid content of 60% to obtain an aqueous polyacrylic acid resin aqueous solution;

[0067] (3) Add 2.5 parts of aminoferrocene to 100 parts of aqueous polyacrylic acid resin aqueous solution and stir evenly, add 1.5 parts of activator, and stir at 55° C. for 4 hours to obtain a modified polyacrylic acid resin aqueous solution.

[0068] Step 2: S1: Use laser drilling equipment to drill aluminum nitride ceramics to form positioning holes and internal conductive holes; clean the drilled ceramics to remove slag at the edges of the micropores to obtain ceramic sheet A;

[0069] S2: The surface of ceramic sheet A is sequentially subjected to ion bombardment cleaning and magnetron sputtering to deposit a metal layer; the outermost two ceramic sheets are sputtered on one side to obtain a single-sided ceramic sheet; the rest are sputtered on both sides to obtain a double-sided ceramic sheet; the sputtered metal layer is divided into two layers, the copper layer is sputtered first, and the titanium layer is sputtered later; the sputtering vacuum is 10 -4 Pa, argon pressure is 0.2Pa; titanium target sputtering power is 8KW, sputtering time is 30min; copper target sputtering power is 15KW, sputtering time is 100min, sputtering temperature is 240℃;

[0070] S3: performing sputtering ceramic patterning processing on the metal layer of the single-sided ceramic sheet and the double-sided ceramic sheet: exposing and developing the film, and etching out fine circuit patterns; thus obtaining a patterned single-sided ceramic sheet and a patterned double-sided ceramic sheet;

[0071] S4: Screen-printing a hole-filling metal slurry on the patterned single-sided ceramic sheet and the patterned double-sided ceramic sheet, and drying them at a temperature of 120° C. for 15 minutes to obtain an outer layer ceramic sheet and a middle ceramic sheet A.

[0072] S5: Attaching metal foil to both sides of the middle ceramic sheet A located in an even number of layers in the multilayer board, sintering at high temperature, and cooling down; the metal foil is a rolled tungsten foil; the sintering temperature is 1150°C, the holding time is 30 minutes, the vacuum degree in the furnace is less than 0.01Pa, and the pressure is 10MPa; thus, the foil-attached middle ceramic sheet A is obtained;

[0073] S6: Etching the surface of the foil-coated intermediate ceramic sheet A with a metal foil pattern: exposing and developing the film to etch out the desired corresponding pattern; aligning and screen-printing the dielectric slurry: screen-printing the dielectric slurry in the gaps between the pattern lines and drying the dielectric slurry model 07HD290; drying at a temperature of 100°C for 15 minutes; obtaining the intermediate ceramic sheet B;

[0074] S7: aligning and installing the outer ceramic sheet, the middle ceramic sheet A, and the middle ceramic sheet B using the positioning holes to form a laminated structure: the outer ceramic sheets are arranged on both outermost surfaces of the multilayer ceramic substrate; the middle portion of the multilayer ceramic substrate is provided with the middle ceramic sheet A on the odd-numbered layers and the middle ceramic sheet B on the even-numbered layers; the number of the middle ceramic layers in the multilayer ceramic substrate is three; and a pre-laminated multilayer ceramic substrate is obtained;

[0075] S8: secondary sintering and cooling of the pre-laminated multi-layer ceramic substrate; the sintering temperature is 1100 DEG C, the holding time is 40 min, the vacuum degree in the furnace is <0.01 Pa, and the pressure is 15 MPa; a base multi-layer ceramic substrate is obtained;

[0076] S9: polishing the surface of the base multi-layer ceramic substrate; using the DPC process to prepare a high-density circuit on the surface of the multi-layer ceramic substrate to obtain a high-precision multi-layer ceramic substrate.

[0077] The metal paste comprises the following raw materials in parts by mass: 89 parts of metal powder, 15 parts of water-based binder, and 0.4 parts of defoamer RJ-6501; the metal powder comprises tungsten powder and copper powder at a mass ratio of 16:3.

[0078] Embodiment 3: Preparation of a high-precision multi-layer ceramic substrate includes the following steps:

[0079] Step one: preparation of modified polyacrylic acid: (1) 2.5 parts of sodium dodecyl sulfate, 1.5 parts of alkylphenol polyoxyethylene ether are added to 40 parts of deionized water and stirred uniformly, 50 parts of methyl methacrylate, 34 parts of butyl acrylate, 9 parts of acrylic acid, and 3 parts of acrylamide are added and stirred uniformly at 150-160 r / min to obtain a monomer emulsion;

[0080] (2) 30 parts of the monomer emulsion and 0.15 parts of ammonium persulfate are added to a reaction kettle, stirred at 80 DEG C for 60 min, 70 parts of the monomer emulsion and 0.5 parts of ammonium persulfate are added dropwise, the dropwise adding time is controlled to be 2.5 h, after the dropwise adding is completed, stirring is carried out at 90 DEG C for 1.5 h, the pH is adjusted to 7.5, the filtrate is obtained by filtration, and water is added for dilution to a solid content of 60% to obtain a water-based polyacrylic acid resin aqueous solution;

[0081] (3) 2.5 parts of aminoferrocene are added to 100 parts of the water-based polyacrylic acid resin aqueous solution and stirred uniformly, 1.5 parts of an activator are added, and stirring is carried out at 55 DEG C for 4 h to obtain a modified polyacrylic acid resin aqueous solution.

[0082] Step two: S1: a laser drilling device is used to drill aluminum nitride ceramic to form positioning holes and internal through holes; the drilled ceramic is cleaned to remove the micro-hole edge slag to obtain a ceramic sheet A;

[0083] S2: the surface of the ceramic sheet A is sequentially subjected to ion bombardment cleaning and magnetron sputtering deposition of a metal layer; the outermost two ceramics are single-sided sputtered to obtain single-sided ceramic sheets; the rest are double-sided sputtered to obtain double-sided ceramic sheets; the sputtered metal layer is divided into two layers, a copper layer is sputtered first, and a titanium layer is sputtered later; the sputtering vacuum degree is 10 -4Pa, argon pressure is 0.2Pa; titanium target sputtering power is 8KW, sputtering time is 30min; copper target sputtering power is 15KW, sputtering time is 100min, sputtering temperature is 240℃;

[0084] S3: sputtering ceramic patterning treatment is carried out on the metal layer of the single-sided ceramic sheet and the double-sided ceramic sheet: film pasting, exposure and development, and etching to form fine line patterns; patterned single-sided ceramic sheet and patterned double-sided ceramic sheet are obtained;

[0085] S4: patterned single-sided ceramic sheet and patterned double-sided ceramic sheet are subjected to alignment screen printing of hole-filling metal paste, and drying is carried out at a drying temperature of 120℃ for 15min; corresponding outer ceramic sheet and intermediate ceramic sheet A are obtained.

[0086] S5: metal foil is attached to the double-numbered intermediate ceramic sheet A in the multilayer board, and high-temperature sintering and cooling are carried out; the metal foil is a calendered tungsten foil; the sintering temperature is 1150℃, the holding time is 30min, the vacuum degree in the furnace is <0.01Pa, and the pressure is 10Mpa; a foil-attached intermediate ceramic sheet A is obtained.

[0087] S6: the surface of the foil-attached intermediate ceramic sheet A is subjected to metal foil pattern etching: film pasting, exposure and development, and etching to form the required corresponding patterns; alignment screen printing of medium paste is carried out: medium paste is screen printed in the pattern line gap and dried, and the medium paste type is 07HD290; drying is carried out at a temperature of 100℃ for 15min; an intermediate ceramic sheet B is obtained.

[0088] S7: the outer ceramic sheet, the intermediate ceramic sheet A and the intermediate ceramic sheet B are aligned and installed by using the positioning holes to form a laminated structure: the outermost two sides of the multilayer ceramic substrate are provided with the outer ceramic sheet; the intermediate part of the multilayer ceramic substrate is provided with the intermediate ceramic sheet A at the odd-numbered layers and the intermediate ceramic sheet B at the double-numbered layers; the number of intermediate ceramic layers in the multilayer ceramic substrate is 3; a pre-laminated multilayer ceramic substrate is obtained.

[0089] S8: the pre-laminated multilayer ceramic substrate is subjected to secondary sintering and cooling; the sintering temperature is 1100℃, the holding time is 40min, the vacuum degree in the furnace is <0.01Pa, and the pressure is 15Mpa; a basic multilayer ceramic substrate is obtained.

[0090] S9: the surface of the basic multilayer ceramic substrate is polished; high-density lines are prepared on the surface of the multilayer ceramic substrate by using the DPC process, and a high-precision multilayer ceramic substrate is obtained.

[0091] The metal paste comprises the following raw materials in parts by mass: 89 parts of metal powder, 14-16 parts of water-based binder and 0.4 parts of defoamer RJ-6501; the metal powder comprises the following substances in parts by mass: 15 parts of silver-coated copper powder and 74 parts of tungsten powder.

[0092] Performance test: the sample prepared according to the method of each embodiment is tested at the through hole resistance, and the experimental data are shown in Table 1.

[0093] Table 1

[0094] Item Resistance / mΩ Example 1 296.1 Example 2 270.9 Example 3 265.3

[0095] Conclusion: from Table 1, it can be seen that, compared with Example 1, the water-based adhesive prepared in Example 2 has good resistance, and the resistance is reduced due to the graphitization of carbon; compared with Example 2, the copper powder is replaced by silver-coated copper powder in Example 3, which has certain improvement on the reduction of resistance.

[0096] In summary, by combining the advantages of AMB and DPC processes, the DPC process is combined with the multi-layer board technology to realize a high-precision multi-layer ceramic substrate with high wiring density. The product has higher reliability and lower cost, can meet the future demand of high-density integrated circuit packaging, and provides a water-based metal paste for through hole metal filling, and reduces the resistivity.

[0097] Finally, it should be noted that: the above only describes the preferred embodiments of the present application, and is not used to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a high-reliability, high-precision multilayer ceramic substrate, characterized in that: The method comprises the following steps: S1: micropore processing is performed on the ceramic sheet to form positioning holes and internal through holes; and cleaning is performed to obtain a ceramic sheet A; S2: the surface of the ceramic sheet A is sequentially subjected to ion bombardment cleaning and surface sputtering of a metal layer to obtain a single-sided ceramic sheet and a double-sided ceramic sheet; S3: sputtering ceramic patterning is performed on the metal layer of the single-sided ceramic sheet and the double-sided ceramic sheet to obtain a patterned single-sided ceramic sheet and a patterned double-sided ceramic sheet; S4: alignment screen printing hole filling is performed on the patterned single-sided ceramic sheet and the patterned double-sided ceramic sheet, and drying is performed to obtain an outer ceramic sheet and an intermediate ceramic sheet A; S5: a portion of the intermediate ceramic sheet A is attached with a metal foil, high-temperature sintering and cooling are performed, and a foil-attached intermediate ceramic sheet A is obtained; S6: surface metal foil patterning etching and alignment screen printing of a medium paste are performed on the foil-attached intermediate ceramic sheet A to obtain an intermediate ceramic sheet B; S7: the outer ceramic sheet, the intermediate ceramic sheet A and the intermediate ceramic sheet B are aligned and installed by using the positioning holes to form a laminated structure, and a pre-laminated multilayer ceramic substrate is obtained; S8: the pre-laminated multilayer ceramic substrate is subjected to secondary sintering and cooling to obtain a basic multilayer ceramic substrate; S9: the surface of the basic multilayer ceramic substrate is polished and polished, and DPC fine line manufacturing is performed to obtain a high-precision multilayer ceramic substrate. In step S7, in the laminated structure of the pre-laminated multilayer ceramic substrate: the outermost two sides of the multilayer ceramic substrate are provided with the outer ceramic sheet; the intermediate part of the multilayer ceramic substrate is provided with the intermediate ceramic sheet A at the odd layers and the intermediate ceramic sheet B at the even layers; and the number of intermediate ceramic layers in the multilayer ceramic substrate is odd.

2. The method of claim 1, wherein the method further comprises: In step S2, during the ion bombardment cleaning, the specific process conditions are as follows: the vacuum degree is 20-1200 Pa, the argon pressure is 0.2-1 Pa, the voltage is 0.6-0.8 KV, and the cleaning time is 180-300 seconds. ​ The sputtering process is magnetron sputtering, and the specific process conditions are as follows: the vacuum degree of the furnace cavity is 10 -4 Pa -3 Pa, the sputtering power is 15-25 KW, the voltage is 500-800 V, the time is 60-180 min, and the temperature is 200-300 DEG C.

3. The method of claim 1, wherein the method further comprises: In step S5, during the high-temperature sintering, the specific process is as follows: the temperature is 900-1500℃, the holding time is 20-90 min, the vacuum degree in the furnace is <0.01 Pa, and the pressure is 10-30 MPa. ​ In step S8, during the secondary sintering, the specific process is as follows: the temperature is 900-1500℃, the holding time is 20-90 min, the vacuum degree in the furnace is <0.01 Pa, and the pressure is 10-30 MPa.

4. The method of claim 1, wherein the method further comprises: In step S2, the thickness of the metal layer is 0.5-5 μm; the metal layer comprises an active metal layer and other metal layers, and the active metal layer is close to one side of the ceramic; the active metal layer comprises one of titanium and zirconium; and the other metal layer comprises one or more of copper, nickel and silver; ​ In step S5, the metal foil comprises one of tungsten foil, molybdenum foil, tungsten-molybdenum foil, molybdenum-copper foil and tungsten-copper foil, and the thickness is 5-30 μm; In step S7, the medium paste comprises one of insulating paste and functional paste.

5. The method of claim 1, wherein the method further comprises: In step S4, during the alignment screen printing hole filling, a metal paste is used. ​ The metal paste comprises the following raw materials in parts by mass: 85-92 parts of metal powder, 8-15 parts of organic matter; the metal powder comprises non-melting metal powder and melting metal powder in a mass ratio of 16:3-4; the non-melting metal powder comprises one or more of tungsten powder, molybdenum powder and tungsten-molybdenum powder; the melting metal powder comprises one or more of copper powder, silver powder and nickel powder; and the organic matter is a terpene alcohol system.

6. The method of claim 5, wherein the method further comprises: The metal paste comprises the following raw materials in parts by mass: 85-92 parts of metal powder, 14-16 parts of water-based adhesive, and 0.3-0.5 parts of defoamer RJ-6501; the metal powder comprises the following raw materials in parts by mass: 14-15 parts of silver-coated copper powder and 70-76 parts of tungsten powder. ​ 7. The method of claim 6, wherein the method further comprises: The water-based adhesive comprises the following raw materials in parts by mass: 13-14 parts of modified polyacrylic acid resin aqueous solution and 1-2 parts of hydroxyethyl cellulose. ​ 8. The method of claim 7, wherein the method further comprises: The preparation method of the modified polyacrylic acid resin aqueous solution comprises the following steps: (1) adding sodium dodecyl sulfonate and alkylphenol polyoxyethylene ether into deionized water and stirring uniformly, adding methyl methacrylate, butyl acrylate, acrylic acid and acrylamide, and stirring uniformly at 150-160 r / min to obtain a monomer emulsion; ​ (2) adding the monomer emulsion and 0.1-0.2 parts of ammonium persulfate into a reaction kettle, stirring at 75-80 ℃ for 50-70 min, adding the monomer emulsion and ammonium persulfate dropwise, controlling the dropwise adding time to be 2-3 h, stirring at 85-90 ℃ for 1-1.5 h after the dropwise adding is completed, adjusting the pH to 6-8, filtering to obtain a filtrate, diluting with water to a solid content of 60%, and obtaining a water-based polyacrylic acid resin aqueous solution; (3) adding aminoferrocene into the water-based polyacrylic acid resin aqueous solution and stirring uniformly, adding an activator, and stirring at 50-60 ℃ for 3-5 h to obtain a modified polyacrylic acid resin aqueous solution.

9. The method of claim 8, wherein the method further comprises: The monomer emulsion comprises the following raw materials in parts by mass: 2-3 parts of sodium dodecyl sulfonate, 1-2 parts of alkylphenol polyoxyethylene ether, 40-45 parts of deionized water, 8-10 parts of acrylic acid and 2-4 parts of acrylamide; ​ The water-based polyacrylic acid resin aqueous solution comprises the following raw materials in parts by mass: 96-104 parts of monomer emulsion and 0.5-0.7 parts of ammonium persulfate; The modified polyacrylic acid resin aqueous solution comprises the following raw materials in parts by mass: 2-3 parts of aminoferrocene, 100 parts of water-based polyacrylic acid resin aqueous solution and 1-2 parts of activator.

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