Preparation method of silver-free AMB nitride ceramic thick copper circuit board

Abstract

The invention provides a preparation method of a silver-free AMB nitride ceramic thick copper circuit board. The preparation method comprises the following steps: step 1, preparing a hollow circuit high polymer template; 2, cutting the oxygen-free copper sheet, leaving a circuit part, and removing a non-circuit part to obtain a copper circuit board; 3, the solder is subjected to electrochemical modification and surface treatment; step 4, cutting the solder, leaving a circuit part, and removing a non-circuit part to obtain a solder circuit board; 5, overlapping and laminating the nitride ceramic substrate, the hollow circuit high polymer template, the solder circuit board and the copper circuit board; and step 6, performing vacuum brazing to obtain the silver-free nitride ceramic thick copper circuit board. The method avoids generation of hazardous wastes such as organic waste residues and heavy metal waste liquid, is more environment-friendly, can quickly realize welding of nitride ceramic and the circuit board, is simple and efficient, and can also be used for preparation of other thick copper type ceramic circuit boards.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nitride ceramic circuit board preparation, in particular to a preparation method of silver-free AMB nitride ceramic thick copper circuit board. BACKGROUND

[0002] With the rapid development of high-tech, nitride ceramic copper-clad circuit boards with high thermal conductivity, low dielectric constant, low dielectric loss, excellent electrical insulation, thermal expansion coefficient matching with silicon, and non-toxicity, etc. gradually become the ideal material for high-density, high-power and high-speed integrated circuit boards and power semiconductor module packaging. It is mainly applied in high-speed rail, electric new energy vehicles, wind power, smart grid, and many other fields such as high-power LED packaging, high-power charging, and semiconductors.

[0003] At present, the preparation forms of nitride ceramic circuit boards mainly include DBC-AMB process, AMB process, and the most advanced LAM laser rapid activation metallization process, but the mainstream preparation process is still mainly AMB active metal brazing. At present, the brazing form of AMB process of nitride ceramic thick copper circuit board mainly includes brazing paste (screen printing, coating), multi-layer active sheet lamination, and Ag-Cu-Ti solder sheet for brazing of copper material, and a series of process procedures such as film pasting, exposure, development, and etching are needed after brazing to form circuit patterns by using traditional PCB manufacturing process, which causes serious environmental pollution. First, the organic solvent, binder, and thickening agent contained in the silver-based brazing paste will cause pores, incomplete volatilization, and even its decomposition will directly affect the overall quality of the circuit board, reducing the yield. The presence of silver not only increases the production cost, but also causes the failure of downstream products such as IGBT, SiC, and power modules, resulting in reliability failure risk. The Ag-Cu-Ti ternary alloy or Ag-Cu-In-Ti quaternary alloy solder sheet avoids the use of organic solvents, but is subject to the problem of multi-alloy rolling process technology, and the thickness of the brazing foil is generally larger, ranging from 50um to 80um, and the price is higher. In the etching process, this will increase the time, water consumption, and accumulation of metal wastewater in the subsequent etching process, making etching difficult and not environmentally friendly. At the same time, during the production process, due to the etching process through film pasting, exposure, development, etching, and film stripping, more waste, slag, and metal waste liquid will be generated, and the waste liquid contains mixed high-concentration heavy metal ions and high-concentration organic waste liquid, which is extremely difficult to handle and causes serious environmental pollution damage.

[0004] At present, the preparation methods of existing nitride ceramic circuit boards mainly include the following:

[0005] (1) The first is to prepare nitride ceramic circuit board in the form of nitride ceramic substrate + active solder paste + screen printing + copper plate sintering + chemical etching (film pasting - exposure - development - etching - film removal).

[0006] (2) The second is to prepare nitride ceramic circuit board in the form of nitride ceramic substrate + pre-oxidation (DBC) + copper plate sintering + chemical etching (film pasting - exposure - development - etching - film removal)

[0007] (3) The third is to prepare nitride ceramic circuit board in the form of nitride ceramic substrate + pre-oxidation (DBC) + active soldering (AMB) + copper plate + chemical etching (film pasting - exposure - development - etching - film removal)

[0008] The fourth is to prepare nitride ceramic circuit board in the form of nitride ceramic substrate + sheet superimposed solder / active alloy sheet solder + copper plate sintering + chemical etching (film pasting - exposure - development - etching - film removal).

[0009] In addition, in the preparation of etching-free silver-free AMB, the disclosed patent "An etching-free AMB copper-clad plate manufacturing method" (Publication No. CN116847559A) provides a preparation scheme using plasma cold spraying technology: first, use plasma cold spraying technology to spray Cu-Sn-Ti-X (at least one of r, V, In, Ni, Zn, P) and other multi-element mixed powder on the copper sheet to obtain a hard-state composite plate. Then vacuum anneal the sprayed copper sheet to obtain a soft-state composite plate. Secondly, the soft-state composite plate is subjected to multiple calendering, milling, adjustment of copper sheet thickness and flatness, and then a certain depth of the non-circuit part of the soldered side is milled and engraved by a method similar to "seal sunken", and then vacuum sintering is performed. After sintering, the other side without solder is milled and engraved again in the same way, i.e. "seal sunken", to show the complete circuit. First, although this technical scheme effectively avoids the environmental problems caused by etching and provides a silver-free soldering scheme, the process flow is more complex, lengthy and requires multiple calendering, annealing and flattening of the copper material, which affects the circuit precision and is difficult to control. Moreover, the circuit pattern is formed by milling and engraving the non-pattern part twice before and after sintering, which means that the thicker the copper, the worse the milling precision will be, and the process will be more complicated. Secondly, although the silver-free AMB copper-clad plate uses silver-free solder, the plasma cold spraying technology generally uses fan-shaped spraying during spraying, so the thickness of the solder layer will be locally uneven, affecting the soldering quality. As an AMB copper-clad plate, the porosity and peel strength, which are key to soldering quality, are not given.

[0010] In the patent No. CN116156772B, a kind of AMB copper-clad ceramic circuit board and its preparation method are involved;Compared with the multiple pre-treatment, film pressing, exposure, development, film removal process of existing negative photosensitive dry film as pattern transfer material, the invention uses positive photoetching dry film as pattern transfer material, and only through once pre-treatment, film pressing, multiple exposure, development, once film removal process can realize the simple preparation of AMB copper-clad ceramic circuit board.The invention reduces the number of film pressing, pre-treatment and film removal, realizes the simplification of process, manpower and energy consumption, greatly improves the production efficiency of AMB copper-clad ceramic circuit board;At the same time, in the process of solder etching and surface treatment, the positive photoetching dry film is attached to the copper surface to act as an etching-resistant layer, avoiding the pollution of copper circuit by chemical solution in the process of solder etching and surface treatment, effectively improving the appearance yield of copper circuit etching.In the preparation process of AMB circuit board, the invention uses positive photoetching dry film, which effectively reduces the number of film attachment pre-treatment, film pressing and film removal process compared with negative photoetching dry film, and the whole circuit preparation process is still the traditional circuit board manufacturing process, without changing the process, and the circuit board preparation process still includes film attachment, exposure, development, etching, film removal process, however, in the circuit board manufacturing process, exposure, development, etching, etching and film removal are the processes that produce a lot of pollution, which will produce a lot of waste, waste residue and metal waste liquid, and the waste liquid containing mixed high-concentration heavy metal ions and high-concentration organic waste liquid is very difficult to handle, and it is serious pollution to the environment.

[0011] In patent number CN114007335A, a preparation method of AMB ceramic copper-clad plate based on cold spraying process is disclosed, which comprises the following steps: ultrasonic cleaning, drying and sand blasting treatment of the ceramic substrate; cold spraying of AMB active filler powder with inert gas as medium to form an active filler coating on the ceramic substrate; cold spraying of high-purity copper powder with inert gas as pneumatic medium to form a copper conductive coating on the active filler coating; high-temperature brazing of the composite coating ceramic plate in a vacuum brazing furnace to realize the brazing fusion of the ceramic substrate, the active filler coating and the copper coating; thinning the ceramic copper-clad plate surface until the set coating thickness and the surface roughness meeting the process requirements are obtained; printing a circuit diagram on the copper-clad plate surface, using a wet etching process to manufacture a circuit board, and then using a surface plating process to prepare an AMB ceramic copper-clad plate product. The patent uses active filler spraying and then copper layer spraying for brazing, which avoids the use of organic binder in brazing paste, but in the process of cold spraying active filler and cold spraying copper layer, the active filler layer and the ceramic substrate are difficult to effectively combine, and the copper layer is also prone to splashing, mutual attachment and damage to the original active layer structure during spraying, resulting in impurities in the copper conductive layer after high-temperature sintering, and even stress problems leading to fracture. Secondly, the invention needs to be thinned and the roughness needs to be adjusted after sintering, which is a complicated process, and the thickness and roughness are difficult to control. Moreover, the copper material of the AMB ceramic circuit board is generally oxygen-free rolled copper with a purity of 99.99%, and the cold spraying technology used to spray the conductive copper layer cannot guarantee the purity and uniformity of the copper. In addition, the wet etching process includes film pasting, exposure, development, etching and film stripping processes, which causes serious environmental pollution.

[0012] The above prior art is quite different from the present application. Through retrieval, no XY documents are found, and the present application has innovation. Since there is no solution in the prior art to solve the technical problems we want to solve, we have invented a new preparation method of silver-free AMB nitride ceramic thick copper circuit board. SUMMARY

[0013] The object of the present application is to provide a silver-free AMB nitride ceramic thick copper circuit board preparation method which can quickly realize the welding of nitride ceramic and circuit board, is simple, efficient and environmentally friendly, and can also be used for the preparation of other thick copper type ceramic circuit boards.

[0014] The object of the present application can be achieved by the following technical measures: a silver-free AMB nitride ceramic thick copper circuit board preparation method, which comprises the following steps:

[0015] Step 1, preparation of the hollowed-out circuit high polymer template;

[0016] Step 2, cutting on the oxygen-free copper sheet, leaving the circuit part, and removing the non-circuit part to obtain the copper circuit board;

[0017] Step 3, electrochemical modification and surface treatment of the solder;

[0018] Step 4, cutting on the solder, leaving the circuit part, and removing the non-circuit part to obtain the solder circuit board;

[0019] Step 5, superimposing the nitride ceramic substrate on the hollowed-out circuit high polymer template, the solder circuit board, and the copper circuit board;

[0020] Step 6, vacuum brazing to obtain the silver-free nitride ceramic thick copper circuit board.

[0021] The purpose of the present application can also be achieved by the following technical measures:

[0022] In step 1, a certain size and thickness of organic high polymer plate is taken, and the circuit diagram is engraved on the organic high polymer plate with a laser cutting machine to remove the engraved circuit part, so that the circuit is hollowed out, and a hollowed-out circuit high polymer template is prepared.

[0023] In step 1, the organic high polymer plate used is one of polyvinyl butyral plate PVB, polymethyl methacrylate plate PMMA, polystyrene plate PS, and polyacrylic plate ABR.

[0024] In step 1, the size of the certain size and thickness of the organic high polymer plate is the same as the size of the nitride ceramic substrate used, and the thickness is half of the thickness of the copper circuit board.

[0025] In step 2, a copper sheet to be welded is taken, and the laser cutting machine is used to cut on the oxygen-free copper sheet, leaving the circuit part, and removing the non-circuit part to obtain the copper circuit board.

[0026] In step 3, a certain proportion of electrolyte is configured, the electrolyte contains acid, inorganic salt, surfactant and water; a certain thickness of Cu-X alloy foil is taken as solder, and anode is pure titanium, pure titanium or pure copper, cathode is Cu-X alloy foil, after electrochemical surface treatment, cleaning and drying are carried out.

[0027] In step 3, X in Cu-X alloy foil is one or more of Ti, Zr, Hf and Cr, the content of copper is 50-99%, the content of X is 1-50%, and the thickness is 10-40um.

[0028] In step 3, in the electrolyte, the acid is one or more of phosphoric acid, hydrofluoric acid, hypophosphorous acid, phosphorous acid, nitric acid, oxalic acid, and the acid content is 5-20% of the mass percentage of the electrolyte; the inorganic salt is one or more of sodium hydrogen phosphate, disodium hydrogen phosphate, ammonium phosphate, phosphorus pentoxide, sodium fluoride, ammonium fluoride, and the inorganic salt accounts for 1-10% of the mass percentage of the electrolyte, the surfactant is one or more of OP-10, polyethylene glycol sulfate, polyoxyethylene ethyl ether, polyethylene glycol ether, sodium dodecyl sulfonate and sodium dodecyl sulfate, and the surfactant accounts for 0.5-1% of the mass percentage of the electrolyte; and the rest is water.

[0029] In step 4, a piece of treated solder is taken, and a laser cutting machine is used to cut the solder to leave a circuit part and remove a non-circuit part, so as to obtain a solder circuit board.

[0030] In step 5, the nitride ceramic used is AlN or SiN.

[0031] In step 6, composite sintering is performed through a vacuum brazing furnace, during the brazing process, the polymer is cracked and volatilized, and the ceramic-solder-copper circuit is connected through mutual diffusion and co-melting, so as to obtain a silver-free nitride ceramic thick copper circuit board without etching.

[0032] The object of the application can also be achieved by the following technical measures: a system for preparing a silver-free AMB nitride ceramic thick copper circuit board by a polymer template method, which uses the method for preparing a silver-free AMB nitride ceramic thick copper circuit board to prepare a silver-free nitride ceramic thick copper circuit board without etching.

[0033] The preparation method of the silver-free AMB nitride ceramic thick copper circuit board in the application relates to the field of nitride ceramic circuit board preparation.The polymer template method is to realize the direct welding of copper circuit and ceramic by relying on a volatile high polymer template, without etching, so that the circuit board can be directly obtained, and the etching of copper and solder is avoided.The silver-free AMB is based on AMB, and silver-free solder with active elements is used for brazing.The application provides a preparation method of the silver-free AMB nitride ceramic thick copper circuit board.The method first uses a carving machine to engrave a circuit pattern on a polymer substrate, removes the circuit board part, and leaves a hollow non-circuit part.Secondly, a laser cutting machine is used to cut the oxygen-free copper sheet, leaving the circuit part and removing the non-circuit part.Meanwhile, the solder is cut, leaving the circuit part and removing the non-circuit board part.Finally, the nitride ceramic and the hollow non-circuit polymer part, the solder circuit part and the oxygen-free copper circuit part are sequentially laminated.Then, composite sintering is performed through a vacuum brazing furnace.During the brazing process, the polymer is cracked and volatilized, the ceramic-solder-copper circuit is diffused to realize eutectic connection, and thus the nitride ceramic thick copper circuit board without etching is obtained.Secondly, in the project, the silver-free brazing material is prepared by using a 10um-40um Cu-X (X is Ti, Zr, Hf, Cr) alloy foil, the alloy foil is surface treated through an electrochemical process, a network-shaped oxide microporous structure is formed on the surface of the alloy foil, the oxide microporous structure provides a channel for metal diffusion, at the same time, the existence of the oxide provides free oxygen elements and a skeleton, which is helpful to welding and prevents the overflow of the brazing material.The composition of the electrolyte liquid participates in diffusion eutectic at high temperature, the welding temperature is reduced, and thus uniform connection of the solder, the ceramic board and the copper circuit is realized, and the porosity is lower.

[0034] Compared with the prior art, the application has the following beneficial effects:

[0035] (1) Compared with the conventional preparation method with etching, the application can avoid the participation of multiple processes such as film pasting, exposure, development, etching and film stripping, realize the formation of a circuit pattern without etching, thereby simplifying the production process, realizing high efficiency, being conducive to environmental protection, and reducing production cost.

[0036] (2) The brazing paste with an organic solvent does not need to be used, so that the pollution of the circuit board caused by the volatilization and overflow of the organic solvent in the brazing paste is effectively avoided.At the same time, the composition of the solder is simple, the welding is realized through the cooperation of the surface microstructure adjustment and the composition of the electrolyte liquid, and the cost is more reduced.

[0037] (3) The polymer template is easy to crack and volatilize, is used for circuit positioning and does not need to be removed, is sintered in the furnace, is cracked and volatilized, does not affect the welding of the solder, realizes direct welding of the circuit, and is easy to operate.

[0038] (4) Compared with the existing etching-free related scheme, a process path with more simplicity is proposed, which can also be used for soldering of various ceramic-based circuit boards, has universality and development potential. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 A schematic diagram of a transparent high polymer substrate hollowed circuit pattern in an embodiment of the present application;

[0040] Figure 2 A schematic diagram of a circuit part after foil cutting in an embodiment of the present application;

[0041] Figure 3 A schematic diagram of a circuit part after laser cutting of soldered copper plate in an embodiment of the present application;

[0042] Figure 4 A schematic diagram of a microstate after electrochemistry of solder in an embodiment of the present application;

[0043] Figure 5 A schematic diagram of peel strength after welding in an embodiment of the present application;

[0044] Figure 6 A schematic diagram of the morphology of a ceramic peeling layer after welding in an embodiment of the present application (EDS.Ti = 15.3%);

[0045] Figure 7 A flowchart of a preparation method of a silver-free AMB nitride ceramic thick copper circuit board in an embodiment of the present application. DETAILED DESCRIPTION

[0046] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0047] It should be noted that the terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations and / or combinations thereof.

[0048] A preparation method of a silver-free AMB nitride ceramic thick copper circuit board in the present application, the preparation process route is as follows:

[0049] Polymer substrate laser engraving circuit diagram → hollow polymer template → brazing foil electrochemical surface modification, treatment → laser cutting leaving circuit diagram part → copper sheet laser cutting leaving circuit diagram part → ceramic substrate, solder circuit part, copper circuit part in turn superimposed → vacuum brazing → silver-free nitride ceramic circuit board.

[0050] As Figure 7 shown, Figure 7 is a flow chart of a specific embodiment of the preparation method of the silver-free AMB nitride ceramic thick copper circuit board, which includes the following steps:

[0051] Step 1, take a certain size and thickness of organic polymer plate, use a laser cutting machine to engrave the circuit diagram on the organic polymer substrate, remove the engraved circuit part, and make the circuit into a hollow, to prepare a hollow circuit polymer template. Figure 1 ).

[0052] Among them, the organic polymer substrate is one of polyvinyl butyral plate (PVB), polymethyl methacrylate plate (PMMA), polystyrene plate (PS), and polyacrylic plate (ABR).

[0053] The size of the certain polymer template is the same as the size of the ceramic substrate used, and the thickness is half of the copper thickness.

[0054] Step 2, at the same time, take a copper sheet that needs to be welded, use a laser cutting machine to cut the oxygen-free copper sheet, leaving the circuit part, and removing the non-circuit part. Figure 3 ).

[0055] Step 3, solder electrochemical modification and surface treatment. Configure a certain proportion of electrolyte, and the electrolyte composition contains acid, inorganic salt, surfactant and water. Take a certain thickness of Cu-X alloy foil, and perform power supply, with pure titanium, pure titanium or pure copper as the anode, and Cu-X alloy foil as the cathode. The electrochemical surface treatment voltage is 10-50V, the current is 1-5A, and the treatment time is 30-120min. After treatment, clean and dry.

[0056] The Cu-X alloy foil contains one or more of Ti, Zr, Hf, and Cr, the copper content is 50-99%, the X content is 1-50%, and the thickness is 10-40um.

[0057] The electrolyte component, the acid is one or more of phosphoric acid, hydrofluoric acid, hypophosphorous acid, phosphorous acid, nitric acid, oxalic acid, and the acid content is 5%-20% of the electrolyte solution, the inorganic compound is one or more of sodium hydrogen phosphate, disodium hydrogen phosphate, ammonium phosphate, phosphorus pentoxide, sodium fluoride, ammonium fluoride, and the inorganic salt ratio is 1%-10%, the surfactant is one or more of OP-10, polyethylene glycol sulfate, polyoxyethylene ethyl ether, polyethylene glycol ether, sodium dodecyl sulfonate and sodium dodecyl sulfate, and the ratio is 0.5%-1%. The rest is water.

[0058] Step 4, take a piece of treated solder foil, use a laser cutting machine to cut on the solder foil, leave the line part, and remove the non-line part. Figure 2 )。

[0059] Step 5, superimpose the nitride ceramic substrate and the hollow line polymer template, the solder line and the copper line in sequence.

[0060] The nitride ceramic is AlN or SiN.

[0061] Step 6, vacuum brazing is performed, and a silver-free nitride ceramic circuit board is obtained.

[0062] Through vacuum brazing furnace for composite sintering, during the brazing process, the polymer is cracked and volatilized, and the ceramic-solder-copper line is diffused to realize co-melting connection, so that the nitride ceramic thick copper circuit board without etching is obtained.

[0063] The vacuum brazing is carried out at a brazing temperature of 950-1000 DEG C, preferably 970 DEG C, and a brazing time of 30-200 min, preferably 150 min.

[0064] The process principle of the application is that the organic polymer which can be volatilized and cracked at high temperature is used as a line template, the line pattern is directly cut and engraved on the polymer sheet by a carving machine, and the polymer in the line part is removed, so that the polymer template with a hollow line part is prepared. Then, the treated Cu-X alloy foil silver-free solder and copper sheet are laser cut, leaving the line part and removing the non-line part. Finally, the nitride ceramic substrate-polymer template-solder line-copper line is superimposed and inlaid in sequence, and then placed in a vacuum brazing furnace for sintering, so that a silver-free AMB nitride ceramic circuit board is obtained.

[0065] In the preparation process of the silver-free solder, the Cu-X alloy foil is used for brazing the nitride ceramic substrate, and the Cu-X alloy foil needs to be subjected to electrochemical modification treatment so as to form a uniform and stable oxide layer, a uniform diffusion channel and a component capable of reducing the melting point. First, the Cu-X alloy foil is rolled by adding an active element based on copper as the main material, has a high melting point, and is difficult to form effective welding when directly used for brazing. Since the vacuum furnace still has a certain oxygen content, uneven oxidation occurs during the welding process, which makes it difficult to weld the oxidized place, and the place without oxidation or with light oxidation forms eutectic liquid phase or brittle compounds too early, resulting in uneven welding. However, after electrochemical treatment, under the combined reaction of voltage, current and electrolyte, the surface of the Cu-X alloy foil brazing foil will be uniformly dissolved and oxidized, thereby forming a uniform honeycomb-shaped oxidation cavity (such as Figure 4 ). The existence of the cavity is caused by the reaction of the precipitated gas, and the composition of the electrolyte liquid also deposits to form an oxide layer during the oxidation process. Therefore, the existence of the uniform cavity provides a uniform and beneficial diffusion channel for the solder, and the composition of the electrolyte liquid participating in the oxidation, such as the phosphorus element, can promote the liquid phase and reduce the eutectic temperature, and the fluorine element in sodium fluoride can ensure that the titanium element is not oxidized. Therefore, the treated Cu-X alloy foil brazing foil can effectively realize the welding of the ceramic substrate and copper.

[0066] The present application provides a preparation method of a silver-free AMB nitride ceramic thick copper circuit board, which solves the problem of cost increase and environmental problems caused by the need for multi-layer etching (copper layer etching and brazing layer etching) in the preparation process of the existing silver-free nitride ceramic circuit board, and proposes a new silver-free welding scheme and an etching-free preparation scheme for ceramic circuit boards, which simplifies the process flow. The method avoids the generation of organic waste, heavy metal waste liquid and other hazardous waste generated by the process flow of exposure, development, etching and film stripping, and is more green and environmentally friendly. At the same time, the silver-free solder greatly reduces the brazing cost, which is conducive to the further development of the new energy field of the upstream and downstream. The present application also provides a solder preparation method, which can quickly realize the welding of the nitride ceramic and the circuit board, and is simple, efficient and environmentally friendly. The method can also be used for the preparation of other thick copper ceramic circuit boards.

[0067] The following are several specific embodiments of the application

[0068] Example 1

[0069] First, take a piece of size 110x110x0.15mm PMMA substrate, laser engraving machine on the poly (methyl methacrylate) (PMMA) substrate line pattern engraving, engraving cutting depth of 0.15mm, so that it is completely engraved through, engraving after the separation of the line part, keep the PMMA substrate with hollow line pattern. Second, take a piece of size 110x110x0.01mm of Cu content of 99%-Ti content of 1% alloy brazing foil, namely Cu 99％ -Ti 1％ Alloy brazing foil. Laser cutting machine on the solder piece line pattern cutting, so that it is completely cut through, cutting after the non line part is removed, keep the solder line pattern.

[0070] Then take a piece of size 110x110x0.3mm copper sheet, laser cutting machine on the copper sheet line pattern cutting, cutting depth of 0.3mm, so that it is completely cut through, cutting after the non line part is removed, keep the copper line pattern.

[0071] Finally, the size of 110x110x0.635mm aluminum nitride and engraved cutting PMMA polymer template, solder line pattern, copper line pattern in turn, single-sided nitride ceramic circuit board can be directly sintered, double-sided silver-free AMB nitride ceramic circuit board the other side also using the same steps above. Then placed in the brazing furnace, vacuum degree 10 -3 Mpa, temperature 970℃, time 150min sintering, sintering after, can get silver-free AMB aluminum nitride ceramic circuit board.

[0072] Cu 99％ -Ti 1％ Alloy foil electrochemical treatment: configuration of 500ml electrolyte, adding mass percentage of 5% acid (phosphoric acid: nitric acid: hydrofluoric acid = 64:10:1), adding mass percentage of 10% inorganic salt (sodium dihydrogen phosphate: sodium fluoride = 24:1), adding mass percentage of 1% surfactant (OP-10: sodium dodecyl sulfonate = 1:3), the rest is water, then the iridium rod and alloy foil are placed in the anode and cathode, set the voltage 10v, current 1A, processing 30min, take out and dry.

[0073] The solder scheme for the sample peel strength test, can reach the same level of silver containing AMB brazing peel strength, far higher than the DBC process (peel strength ≥5N / mm), peel strength of 12N / mm Figure 5 ), porosity of 0.16%., Figure 4SEM of the aluminum nitride ceramic interface layer after peeling, surface particles are generated by the ceramic layer after peeling, and EDS detects 15.3% of Ti element Figure 6 ), indicating that full bonding is achieved between the ceramic.

[0074] Example 2

[0075] First, take a piece of polyvinyl butyral substrate with a size of 110x110x0.2mm, use a laser engraving machine to engrave the line pattern on the polyvinyl butyral (PVB) substrate, the engraving cutting depth is 0.2mm, so that it is completely engraved, after engraving, separate the line part, and reserve the PVB substrate with the hollow line pattern. Second, take a piece of electrochemically treated Cu 75％ -Ti 25％ alloy solder foil, use a laser cutting machine to cut the line pattern on the solder piece, so that it is completely cut through, after cutting, remove the non-line part, and reserve the solder line pattern.

[0076] Then take a piece of copper sheet with a size of 110x110x0.4mm, use a laser cutting machine to cut the line pattern on the copper sheet, the cutting depth is 0.4mm, so that it is completely cut through, after cutting, remove the non-line part, and reserve the copper line pattern.

[0077] Finally, the aluminum nitride with a size of 110x110x0.8mm is overlapped and overlapped with the engraved and cut PVB polymer template, solder line pattern and copper line pattern in turn, the single-sided aluminum nitride ceramic circuit board can be directly sintered, and the other side of the double-sided silver-free AMB aluminum nitride ceramic circuit board is also processed by the same steps. Then place it in a soldering furnace, vacuum degree 10 - 3 Mpa, temperature 990℃, time 150min, sintering, after sintering, silver-free AMB aluminum nitride ceramic circuit board is obtained.

[0078] Cu 75％ -Ti 25％ Electrochemical treatment of Cu-Ti alloy foil: prepare 500ml electrolyte, add 10% acid solution (phosphoric acid: nitric acid: oxalic acid = 60:10:5) by mass percentage, add 5% inorganic salt (sodium dihydrogen phosphate: diaphthong = 20:5) by mass percentage, add 0.75% surfactant (polyethylene glycol ether: sodium dodecyl sulfonate = 1:3) by mass percentage, the rest is water, then put the iridium rod and the alloy foil in the anode and cathode respectively, set the voltage to 25v, the current to 2.5A, and process for 75min, then take out, wash and dry.

[0079] Example 3

[0080] First, take a piece of Cu 50％ -Ti 50％ Electrochemical treatment of alloy foil: 500ml electrolyte solution is configured, 20% acid solution (phosphoric acid: nitric acid: hydrofluoric acid = 64:1:10) is added, 1% inorganic salt (sodium dihydrogen phosphate: sodium fluoride = 24:1) is added, 0.5% surfactant (OP-10: sodium dodecyl sulfonate = 1:3) is added, and the rest is water. Then, the iridium rod and the alloy foil are placed in the anode and the cathode respectively, the voltage is set to 50v, the current is set to 5A, and the treatment is performed for 120min. After taking out, cleaning and drying, it is ready.

[0081] Subsequently, a polyvinyl butyral substrate with a size of 110x110x0.02mm, a treated alloy foil with a size of 110x110x0.04mm, and a copper sheet with a size of 110x110x0.4mm are sequentially stacked. After stacking, the three are simultaneously cut according to the circuit diagram using a laser cutting machine. After cutting, the polymer substrate removes the circuit part, the solder removes the non-circuit part, and the copper sheet removes the non-circuit part. Then, it is combined with a silicon nitride ceramic substrate with a size of 110x110x0.32mm, and directly placed in a vacuum brazing furnace with a vacuum degree of 10 -3 Mpa, temperature 1000℃, time 200min for sintering. After sintering, the silver-free AMB silicon nitride ceramic circuit board is obtained.

[0082] Example 4

[0083] First, take a piece of Cu 99％ -Zr 1％ Electrochemical treatment of alloy foil: 500ml electrolyte solution is configured, 20% acid solution (phosphoric acid: nitric acid: hydrofluoric acid = 64:1:10) is added, 1% inorganic salt (sodium dihydrogen phosphate: sodium fluoride = 24:1) is added, 0.5% surfactant (OP-10: sodium dodecyl sulfonate = 1:3) is added, and the rest is water. Then, the iridium rod and the alloy foil are placed in the anode and the cathode respectively, the voltage is set to 50v, the current is set to 5A, and the treatment is performed for 120min. After taking out, cleaning and drying, it is ready.

[0084] Then, polyacrylic base sheet (ABR) with size of 110x110x0.15mm, treated alloy foil with size of 110x110x0.3mm and copper sheet with size of 110x110x0.3mm are laminated in sequence. After lamination, the three are simultaneously cut according to the circuit diagram by using laser cutting machine. After cutting, the polymer base plate removes the circuit part, the solder removes the non-circuit part, the copper sheet removes the non-circuit part, then laminated with aluminum nitride ceramic substrate with size of 110x110x0.635mm, directly placed in vacuum brazing furnace, vacuum degree 10 -3 Mpa, temperature 970℃, time 150min for sintering, after sintering, the silver-free AMB aluminum nitride ceramic circuit board is obtained.

[0085] Finally, it should be pointed out that the above only for the preferred embodiments of the present application, and is not intended to limit the present application, although the foregoing detailed description of the present application is made with reference to the foregoing examples, for those skilled in the art, it still can be modified, or part of the technical features of the equivalent replacement. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application, should be included in the scope of protection of the present application.

[0086] In addition to the technical features described in the specification, are known to those skilled in the art.

Claims

1. A method for preparing a silver-free AMB nitride ceramic thick copper circuit board, characterized in that, The preparation method of this silver-free AMB nitride ceramic thick copper circuit board includes: Step 1: Prepare a polymer template with hollowed-out lines; Step 2: Cut the oxygen-free copper sheet, leaving the circuit part and removing the non-circuit part to obtain a copper circuit board; Step 3: Electrochemically modify and surface treat the solder; Step 4: Cut the solder to leave the circuit part and remove the non-circuit part to obtain the solder circuit board; Step 5: Overlap the nitride ceramic substrate with the hollowed-out polymer template, solder circuit board, and copper circuit board. Step 6: Perform vacuum brazing to obtain a silver-free nitride ceramic thick copper circuit board.

2. The method for preparing a silver-free AMB nitride ceramic thick copper circuit board according to claim 1, characterized in that, In step 1, take an organic polymer board of a certain size and thickness, and use a laser cutting machine to engrave the circuit diagram on the organic polymer board to remove the engraved circuit part, so that the circuit forms a hollow shape, and prepare a hollow circuit polymer template.

3. The method for preparing a silver-free AMB nitride ceramic thick copper circuit board according to claim 2, characterized in that, In step 1, the organic polymer board used is one of the following: polyvinyl butyral board (PVB), polymethyl methacrylate board (PMMA), polystyrene board (PS), and polyacrylate board (ABR).

4. The method for preparing a silver-free AMB nitride ceramic thick copper circuit board according to claim 2, characterized in that, In step 1, the size of the organic polymer board of a certain size and thickness is the same as that of the nitride ceramic substrate used, and the thickness is half the thickness of the copper circuit board.

5. The method for preparing a silver-free AMB nitride ceramic thick copper circuit board according to claim 1, characterized in that, In step 2, take a copper sheet that needs to be soldered, and use a laser cutter to cut the oxygen-free copper sheet, leaving the circuit part and removing the non-circuit part to obtain a copper circuit board.

6. The method for preparing a silver-free AMB nitride ceramic thick copper circuit board according to claim 1, characterized in that, In step 3, a certain proportion of electrolyte is prepared, which contains acid, inorganic salt, surfactant and water; a piece of Cu-X alloy foil of a certain thickness is taken as solder, and electricity is passed through it. The anode is pure titanium, pure titanium or pure copper, and the cathode is Cu-X alloy foil. After electrochemical surface treatment, it is cleaned and dried.

7. The method for preparing a silver-free AMB nitride ceramic thick copper circuit board according to claim 6, characterized in that, In step 3, the Cu-X alloy foil contains X as one or more of Ti, Zr, Hf, and Cr, with a copper content of 50-99%, an X content of 1-50%, and a thickness of 10-40 μm.

8. The method for preparing a silver-free AMB nitride ceramic thick copper circuit board according to claim 6, characterized in that, In step 3, the electrolyte contains one or more of the following acids: phosphoric acid, hydrofluoric acid, hypophosphoric acid, phosphorous acid, nitric acid, and oxalic acid, with an acid content of 5%–20% of the electrolyte mass; one or more of the following inorganic salts: sodium hydrogen phosphate, disodium hydrogen phosphate, ammonium phosphate, phosphorus pentoxide, sodium fluoride, and ammonium fluoride, with an inorganic salt content of 1%–10% of the electrolyte mass; one or more of the following surfactants: OP-10, polyethylene glycol sulfate, polyoxyethylene ethyl ether, polyethylene glycol ether, sodium dodecyl sulfonate, and sodium dodecyl sulfate, with a surfactant content of 0.5%–1% of the electrolyte mass; and the remainder is water.

9. The method for preparing a silver-free AMB nitride ceramic thick copper circuit board according to claim 1, characterized in that, In step 4, take a piece of processed solder and use a laser cutter to cut the solder, leaving the circuit part and removing the non-circuit part to obtain the solder circuit board.

10. The method for preparing a silver-free AMB nitride ceramic thick copper circuit board according to claim 1, characterized in that, In step 5, the nitride ceramics used are AlN and SiN.

11. The method for preparing a silver-free AMB nitride ceramic thick copper circuit board according to claim 1, characterized in that, In step 6, composite sintering is carried out in a vacuum brazing furnace. During the brazing process, the polymer decomposes and volatilizes, and the ceramic-solder-copper circuit diffuses into each other to achieve fusion connection, thus obtaining a silver-free nitride ceramic thick copper circuit board that does not require etching.

12. A system for preparing silver-free AMB nitride ceramic thick copper circuit boards using a polymer template method, characterized in that, The system for preparing silver-free AMB nitride ceramic thick copper circuit boards using the polymer template method described in any one of claims 1-11 prepares silver-free AMB nitride ceramic thick copper circuit boards that do not require etching.

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