Printing paste supply device, screen printing machine, and method for manufacturing ceramic circuit board using the same

Abstract

To enable uniform printing with excellent cost performance in cases such as printing an active metal paste on a large ceramic substrate or printing an etching resist on a ceramic substrate to which a metal plate is joined.SOLUTION: A printing paste supply device comprises: a container member which contains a printing paste; a supply pipe having a switching valve; and a mechanism which supplies the printing paste from the container member to a discharge port through the supply pipe. A distance from the switching valve to the discharge port is 0.2 m or more and 3 m or less, and a ratio (C / B) of pressure C (MPa) applied to the container to an inner diameter B (mm) of the supply pipe is 0.10 or less. Further, viscosity of the printing paste is 5 Pa s or more and 100 Pa s or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The embodiment generally relates to a printing paste supply device, a screen printing machine, and a method for printing a printing paste using the same. The present invention also relates to a method for manufacturing a ceramic circuit board. [Background technology]

[0002] Ceramic circuit boards are used in semiconductor devices that incorporate semiconductor elements such as power elements. The ceramic substrate and the metal circuit are bonded together via a bonding layer made of active metal brazing material. This improves the bonding strength and heat cycle characteristics. As reliability improves, ceramic circuit boards are increasingly used in automobiles (including electric vehicles) and electric railways. They are used in vehicles, solar power generation facilities, inverters for industrial machinery, etc. In any semiconductor device, a semiconductor element is mounted on the circuit section. For this reason, wire bonding or metal terminals may be used. In this case, semiconductor elements, wire bonding, metal terminals, etc. are joined to the circuit section.

[0003] The method of forming the bonding layer of the ceramic circuit board is to paste active metal brazing material. A method of screen printing the resulting mixture onto a ceramic substrate has been disclosed (Patent Document 1). According to patent document 1, an active metal paste is applied to a silicon nitride substrate of 40 mm x 50 mm x 0.32 mm. The pattern is printed.

[0004] On the other hand, in order to reduce the manufacturing cost of ceramic substrates, they are manufactured in larger shapes. Among ceramic substrates, it has high strength and toughness, and also has high heat dissipation properties. The silicon nitride substrate disclosed has a size of 220 mm x 220 mm x 0.32 mm. It is disclosed in Patent Document 2.

[0005] Also, a method for forming a pattern on a copper plate-bonded ceramic substrate has been disclosed (Patent Document 3). According to Patent Document 3, a process of forming a brazing material by screen printing and an etching resist A pattern circuit can be formed by forming a pattern on a copper plate using a solder paste and then etching it. do.

[0006] Furthermore, as a paste supply device for a screen printing machine, the paste in the paste can is compressed and emptied. The device is disclosed in which air is supplied to the screen by a nozzle via a hose ( According to Patent Document 4, the ink can be printed without stopping the printing press and having to be manually operated by a human. It is possible to supply [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2022 / 131273 [Patent Document 2] Patent No. 6399252 [Patent Document 3] Japanese Patent Application Publication No. 4-17088 [Patent Document 4] Japanese Patent Application Laid-Open No. 2002-144525 Summary of the Invention [Problem to be solved by the invention]

[0008] As semiconductor devices become more compact and high performance, ceramic circuits are required to have high insulation and heat dissipation properties. Components are also required to be smaller and have higher heat dissipation. Among ceramic substrates, silicon nitride substrates have a high Because it combines strength and high insulation, ceramic circuit boards using silicon nitride substrates are On the other hand, in order to reduce manufacturing costs, many circuit boards are manufactured at once. A large ceramic substrate is used to allow for easy fabrication.

[0009] However, since ceramic substrates are sintered bodies of inorganic materials, when they become thin and large, they tend to have reflections on the surface. On the other hand, the active metal printed on the ceramic substrate for bonding is easily damaged. The metal paste uses large metal particles and contains only a small amount of organic components that are removed before heat bonding. It is difficult to print evenly because the surface is set to a smooth surface. The etching resist to be printed has high viscosity, and the ceramic substrate is bonded to a metal plate. The surface of the metal plate is affected by the warping of the ceramic substrate and the difference in thermal expansion between the ceramic and metal. Because of the warping, it is difficult to print evenly without any unevenness.

[0010] The embodiment is intended to solve such a problem, and is applicable to a large ceramic substrate. When printing a conductive metal paste or bonding a ceramic metal substrate to a metal plate, When printing etching resist, it is cost-effective and has excellent quality. Resist supply device and printer that enable printing, and ceramic circuit board using the same This relates to a method for manufacturing a plate. [Means for solving the problem]

[0011] The printing paste supply device according to the embodiment includes a container member for holding the printing paste, A supply pipe having a change valve, and a supply pipe for supplying printing paste from the container member to the injection port. and a mechanism for supplying the liquid. In addition, the distance from the switching valve to the injection port is 0.2 The pressure C (MPa) applied to the container for the inner diameter B (mm) of the supply pipe is ) is 0.10 or less. [Brief explanation of the drawings]

[0012] [Figure 1] Schematic diagram showing an example of a printing paste supply device according to an embodiment. [Figure 2] FIG. 1 is a schematic diagram illustrating an example of a printing press according to an embodiment. [Figure 3] 1 is a cross-sectional view of a process flow illustrating an example of screen printing using a printing machine according to an embodiment; [Figure 4] 1 is a schematic diagram illustrating a printing state of a scraper according to an embodiment from above; [Figure 5] 1 is a cross-sectional view showing an example of a process flow of a ceramic circuit board according to an embodiment; [Figure 6] 1 is a front view showing an example of a semiconductor device using a ceramic circuit substrate according to an embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0013] The printing paste supply device according to the embodiment includes a supply container for holding the printing paste, A supply pipe with a change valve, and a supply pipe from a supply container to an injection port for printing paste. and a mechanism for supplying the liquid. In addition, the distance from the switching valve to the injection port is 0.2 The pressure C (MPa) applied to the container for the inner diameter B (mm) of the supply pipe is ) is 0.10 or less.

[0014] The printing paste supply device according to the embodiment will be described below with reference to the drawings. 1 is a schematic diagram showing an example of a cross section of a printing paste supplying device according to an embodiment. In this case, 1 is a printing paste supply device, and 2 is a printing paste supply container (hereinafter referred to as " 21 is a pressure vessel, 22 is a paste vessel, 3 is an air injection pipe, 4 is a is the paste supply pipe, 5 is the pressure gauge, 6 is the switching valve, and 7 is the injection port. A paste container 22 is placed inside the pressure container 21, and the paste 8 is placed inside the paste container 22. The paste 8 in the paste container 22 is in a state where it is in a paste state. An air supply pipe 4 is inserted into the pressure vessel 21. An air injection pipe 3 is connected to the pressure vessel 21. By injecting air into the pressure vessel 21, pressure is applied to the pressure vessel 21 to supply the paste 8. The paste 8 is extruded into the tube 4. The extruded paste 8 is injected from the injection port 7. The pressure is measured by a pressure gauge 5 and adjusted to a suitable pressure for extrusion. The timing of injection from the injection port 7 is adjusted by the switching valve 6 in the middle of the injection supply pipe 4. Adjust.

[0015] The pressure vessel 21 is a vessel that can withstand the internal pressure described below. It is a cylindrical metal container with a lid on the top, etc., so that the paste container 22 can be easily inserted and removed. This is a possible structure. In order to visually check the volume of the paste, a part of the paste is made of a transparent material such as glass. The paste container 22 may be made of a material that does not react with the solvent of the paste. The paste supply pipe 4 may be made of any suitable material, such as a metal or resin container. The material must be such that the printing paste can move smoothly and does not react with the paste solvent. It is sufficient to use a pipe made of metal or resin. The paste supply pipe in the above case is used in a movable area as described later, so it is made of flexible material such as resin. The switching valve 6 is preferably made of a material that does not react with the solvent of the printing paste used. It is sufficient if the valve is made of a material such as a diaphragm valve, ball valve, butterfly valve, etc. Examples include lubes and gate valves.

[0016] If the distance between the switching valve 6 and the injection port 7 is L, the length of L is 0.2 m or more and 3 m or less. If the length of L is less than 0.2 m, the paste will be injected by the switching signal. The time for signal output becomes too short, making it difficult to time the pressure in the supply container 2. The force is directly transmitted to the nozzle 7, which may result in excessive paste supply. If the length of L is longer than 3m, the time until the paste is injected by the switching signal will be The timing of sending a signal becomes difficult because the pressure in supply container 2 is too high. This may cause the paste to be difficult to reach the nozzle 7, resulting in a shortage of paste. , more preferably 0.3 m or more and 2.5 m or less, and even more preferably 0.5 m or more and 2 m or less. The following is the result.

[0017] In addition, the pressure C (MPa) applied to the container for the inner diameter B (mm) of the paste supply pipe 4 is The ratio (C / B) of the supply pipe 4 is 0.10 or less. The amount of paste increases, the time required to supply paste is shortened, and productivity is improved. In order to increase the inner diameter of the paste supply pipe 4, a larger pressure is applied. The ratio (C / B) of the pressure C (MPa) applied to the container to the inner diameter B (mm) of 4 is 0 It is preferable that the pressure applied to the container is less than 0.10. If the ratio (C / B) to C (MPa) is greater than 0.10, sufficient pressure can be applied. This may result in a decrease in the amount of paste being injected or the paste being unstable. The lower limit of the ratio (C / B) of the pressure C applied to the vessel to the inner diameter B of the vessel is not particularly set. However, if it is too small, it will put a load on the supply pipe and pressure vessel, so it should be 0.01 or more. Therefore, it is preferable to set the ratio of the pressure C applied to the container to the inner diameter B of the supply pipe ( A more preferable value of C / B is 0.02 or more and 0.08 or less.

[0018] In the printing paste supply device according to the embodiment, the viscosity of the printing paste is 10 mPa .S or more and 250 Pa.S or less.

[0019] In the printing paste supply device according to the embodiment, the pressure of the pressure vessel 21 and the pressure of the paste supply pipe By controlling the inner diameter of the nozzle 4 and the distance from the switching valve 6 to the injection port 7, Controls the injection of printing paste with a viscosity of 100 Pa.S or more and 250 Pa.S or less. If the viscosity of the resin is low, less than 10 mPa.S, the fluidity will be high and the injection amount may become large. If the viscosity is higher than 250 Pa.S, the fluidity of the paste will be low. This may result in a decrease in the amount of paste injected or clogging in the supply pipe. Therefore, the viscosity of the printing paste is more preferably 20 mPa.S or more. It is below 0 Pa.S.

[0020] In the printing paste supply device according to the embodiment, the switching valve is a diaphragm valve. It is Bu.

[0021] In the printing paste supply device according to the embodiment, the printing paste is supplied by the switching valve 6. The switching valve 6 is a diaphragm valve. Diaphragm valves use a diaphragm (separating membrane) made of rubber or other materials. This is a valve that opens and closes the flow path, and the drive unit is isolated from the flow path by a diaphragm. It has excellent sealing properties. In addition, the fluid passage is streamlined to minimize liquid accumulation and has self-cleaning properties. Furthermore, it is a simple design with three units: the drive unit, the diaphragm, and the main body. This is because it has a simple structure and is easy to maintain.

[0022] In the printing paste supply device according to the embodiment, the printing paste is an active metal paste. Or it is an etching resist.

[0023] Active metal paste tends to cause uneven printing compared to paste used for ceramic bonding. Molybdenum (Mo) paste used for high melting point metallization is made of Mo powder. Manganese (Mn) powder is added and crushed to make the particle size small and uniform. This is to promote the reaction between the ceramic and the glass component. Since bonding is performed by heating at high temperatures, the paste must contain a large amount of organic components, which improves printability. The organic components are removed during the high temperature heating process. In this case, metal components containing active metals are mixed. The bonding process reacts with ceramics at low temperatures below 900°C, demonstrating the properties of the active metal powder. In addition, the active metal paste is heated at a low temperature, so the organic compound It is desirable to set the amount of organic components to a small value because the components are difficult to remove. Compared to metal paste, active metal paste has large particle size metal components and less organic components. Therefore, it is prone to uneven printing.

[0024] Ceramic circuit boards are made by bonding a ceramic substrate and a metal plate with a bonding layer made of paste. The metal plate to be joined is flat relative to the ceramic substrate, and there are few irregularities on the surface. In contrast, ceramic substrates are sintered bodies and therefore require polishing or other processes. In addition, the warping and unevenness of each ceramic substrate Therefore, the printed surface is not nearly flat and uneven printing is likely to occur. In addition, the active metal paste used to form the bonding layer bonds the ceramic substrate and the metal plate. In addition to the function of providing heat, the thickness is also necessary to mitigate the difference in thermal expansion. It is required to apply the conductive metal paste uniformly to the ceramic substrate without causing uneven printing. It is being done.

[0025] As mentioned above, in a ceramic-metal bonded substrate in which a metal plate is bonded to a ceramic substrate, As plates become larger and thinner, warping and undulation occur. The etching resist printed on the metal plate to form the path is 10 to 50 Pa.S. It has a medium viscosity. If the viscosity of the etching resist is lowered to allow smooth printing, It is difficult to form fine print patterns. Also, the viscosity increases due to exposure to etching liquid. Therefore, the ceramic metal bonding substrate is used for etching. It is preferable to supply the resist in appropriate amounts for printing.

[0026] There are two main types of etching resist: heat-curing and UV (ultraviolet)-curing. The mold hardens at high temperatures because the bonds between the molecules are strengthened by heating it to a specific temperature. Therefore, it is used in applications where heat resistance is required. It is also resistant to many chemicals. UV curing type is a type that changes molecules when exposed to ultraviolet light of a specific wavelength. The curing process is quick, reducing the processing time. Since it can be set lower than the temperature of the mold, fine patterns can be formed.

[0027] The screen printing machine according to the embodiment includes the printing paste supply device.

[0028] As described above, productivity is improved when the printing paste supply device according to the embodiment is used. Therefore, if the screen printing machine is provided with the printing paste supply device according to the embodiment, the printing efficiency will be improved. Can be screen printed well.

[0029] FIG. 2 is a schematic diagram showing an example of a cross section of a screen printing machine according to an embodiment. This is an example of printing a printing paste (etching resist) onto a ceramic bonding substrate. 9 is a screen printing machine, 10 is a screen plate, 11 is a screen frame, and 12 is a printing page. 13 is a squeegee that presses the paste into the screen, and 13 is a printing paste that is applied to the printing starting point after printing. A return scraper, 14 is a ceramic metal bonded substrate, 15 is a printing table, 16 is a stand (printing In FIG. 2, as shown by the dotted line, there is a printing table 15 on the right side of the screen printing machine 9. In this state, the ceramic metal bonding substrate 14 is placed on the printing table 15, and the printing table 15 is The supply device 1 is installed on a stand 16. The supply device 1 may not be installed on the screen printing machine 9 but may be installed in another location.

[0030] FIG. 3 is a cross-sectional view showing an example of a printing process by the screen printing machine 9 according to the embodiment. 1(a) is a cross-sectional view before printing. The paste 8 is in the direction of the movement of the squeegee 12 and the paste supply pipe 4. The ejection port 7 is located between the squeegee 12 and the scraper 13. It applies moderate pressure on the screen to move the paste while pressing it against the openings in the screen. The scraper serves to return the paste after screen printing to its original position before printing. Paste 8 is supplied onto the screen from the injection port 7. Ceramic is placed on the printing table 15. The scraper 13 is separated from the screen plate and is fixed to the metal bonding substrate 14. (b) is a cross-sectional view after printing. The pressure on the screen is The screen has returned to the state shown in (a). The paste 8 is printed on the upper surface of the metal bonding substrate 14. The squeegee 12 applies downward pressure. The paste 8 is pushed out onto the ceramic-metal bonding substrate 14 by moving the device while adding the paste. The paste supply pipe 4 and the scraper 13 move in conjunction with the squeegee 12 while remaining positioned above. (c) shows the state in which the squeegee 12 has moved upward. The paste supply pipe 4 is positioned upward. (d) shows the scraper 13 moving downwards. b) Moving in the opposite direction to the printing direction, the paste on the screen is returned to its pre-printing position. The paste supply pipe 4 and the squeegee 12 move while remaining in the upper position. After that, the scraper 13 moves upward, and the paste supply pipe 4 and the squeegee 12 move downward. The printed ceramic-metal bonding substrate 14 is then ejected and a new ceramic-metal bonding substrate is printed. The substrate 14 is placed on the printing table 15 and returns to the state shown in (a).

[0031] In FIG. 3, the paste 8 is supplied in the state (a), but the paste is scraped off by the scraper 13. Since the paste 8 is returned to the state before printing, it is possible to supply the paste 8 even in the state of (d). It can also be used in the states (b) and (c) where the squeegee 12 is in the position immediately after printing. When the paste 8 is supplied in the states (b) and (c), The paste 8 is spread on the screen 10 by the scraper 13. The supply location does not have to be one, but can be two or more, for example, (a) and (b). good.

[0032] In the method for manufacturing a ceramic circuit board according to the embodiment, the above-described screen printing machine is used. The active metal paste is printed on the ceramic substrate and heated to bond the metal plate. The etching resist is printed on the metal plate, and after printing, etching is performed to form the metal Form a circuit.

[0033] FIG. 4 shows a ceramic-metal bonding substrate in which a metal plate is bonded to a ceramic substrate according to an embodiment. 4(a) is a schematic diagram showing an example of a state in which an etching resist is printed on a plate. The ceramic-metal bonding substrate 14 is a ceramic substrate. 17 and a metal plate 19 are joined together, and an etching resist 20 is applied to the surface of the metal plate 19. In FIG. 4(a), the etching resist 20 is printed in nine places in a 3×3 pattern. However, the embodiment is not limited to the illustrated form, and other forms or quantities may be printed. It is good to etch the ceramic metal bonded substrate after printing the etching resist. A ceramic circuit board is formed by the above steps.

[0034] In the method for manufacturing a ceramic circuit board according to the embodiment, the ceramic substrate is made of silicon nitride. The substrate is one of a bare substrate, an aluminum nitride substrate, and an aluminum oxide substrate.

[0035] The ceramic substrate 17 may be a silicon nitride substrate, an aluminum nitride substrate, or an aluminum oxide substrate. The Al substrate is also preferably one of aluminum oxide substrates. Algil is a type of aluminum oxide that is 20 to 80% by mass and the remaining The aluminum nitride substrate and the aluminum oxide substrate are sintered bodies in which the zirconium oxide is present. The three-point bending strength of the Al substrate is about 300 to 450 MPa. The three-point bending strength of silicon nitride substrates is 600 MPa or more, and even 70 The thermal conductivity of the silicon nitride substrate can be increased to 50 W / (m· It is possible to increase the strength to 80W / (m K) or more, and even to 80W / (m K) or more. Silicon nitride substrates have both high strength and high thermal conductivity. Therefore, the thickness of the silicon nitride substrate can be reduced, and the heat dissipation can be improved. The thickness is preferably 0.635 mm or less, more preferably 0.3 mm or less. Although there is no particular setting, it is preferable that the thickness is 0.1 mm or more. This is to ensure the electrical insulation of the substrate. This refers to the dimension in the direction connecting the bottom surfaces. These ceramic substrates may be single plates. Alternatively, the ceramic substrate may have a three-dimensional structure such as a multi-layer structure. By making the ceramic circuit board thinner and the metal circuit thicker, Thermal resistance is improved.

[0036] In the method for manufacturing a ceramic circuit board according to the embodiment, the metal circuit is made of copper or a copper alloy. is.

[0037] The metal plate 19 used for the metal circuit is made of copper, copper alloy, aluminum, aluminum alloy, etc. Copper and copper alloys have high electrical conductivity and are excellent for use in electrical circuits. It has high conductivity and is also excellent at dissipating heat from the semiconductor elements installed. Copper (pure copper) is oxygen-free copper, Copper alloys include tough pitch copper, deoxidized copper, beryllium copper, chromium copper, titanium copper, and copper tungsten. Examples include:

[0038] Next, a method for manufacturing a ceramic circuit board according to an embodiment will be described. As long as the substrate has the above-described configuration, there is no particular limitation on the manufacturing method. An example of a method for obtaining ceramic circuit boards with a high yield will be given below.

[0039] FIG. 5 is a cross-sectional view showing an example of a process flow of a ceramic circuit board according to an embodiment. In Figure 5(a), a ceramic substrate is used. The ceramic substrate is a silicon nitride substrate, an aluminum nitride substrate, etc. A substrate selected from the group consisting of an aluminum substrate and an aluminum oxide substrate is particularly preferred. Considering the heat dissipation of the entire substrate, the ceramic substrate must have a thermal conductivity of 50W / (m·K) or more. It is also preferable that the substrate is a silicon nitride substrate having a three-point bending strength of 600 MPa or more. The circuit on the top surface of the board is electrically connected to the circuit on the bottom surface by a through hole. When the ceramic substrate is to be subjected to the heat treatment, a ceramic substrate having a through hole is prepared. In this case, through holes may be provided in advance in the molded body. Through holes may be provided in the ceramic sintered body (aluminum-based sintered body). The through holes can be formed by laser processing, cutting processing, etc. The cutting process may be a hole drilling process using a drill or the like.

[0040] In FIG. 5(b), both surfaces (top and bottom surfaces) of the ceramic substrate 17 are printed by the printing method described above. The active metal paste 18 is printed on the surface of the substrate. The active metal paste is used for ceramic bonding and is then dried to remove the solvent. In contrast, active metal paste has a large particle size, which makes it easier to print unevenly. In the past, metal components containing large amounts of active metals were mixed. The properties of the active metal powder are fully utilized because the powder reacts with the ceramic at a low temperature of 900°C or less. In addition, the active metal paste is heated at a low temperature, so the organic components It is desirable to set the amount of organic components that are difficult to remove as low as possible. Since stoichiometric ink contains large particle size metal components and few organic components, it is prone to uneven printing.

[0041] Active metal pastes include silver (Ag), copper (Cu), titanium (Ti), and zirconium (Zr). , hafnium (Hf), niobium (Nb), tin (Sn), indium (In), zinc (Zr ), aluminum (Al), silicon (Si), carbon (C), and magnesium (Mg) It is preferable that the metal circuit contains at least two selected from the group consisting of copper or copper alloy. In the case of gold, a bonding layer containing Cu and Ti is provided between the ceramic substrate and the circuit. The bonding layer containing Cu and Ti is preferably formed using an active brazing metal. is an active metal. In addition to Ti, other active metals include Zr, Hf, and Nb. Examples of active metal brazing materials include mixtures of Ti, Cu, and Ag. The content of Ti in the metal component is 0.1 to 10 mass %, and the content of Cu is 10 to 60 mass %. %, and the balance is Ag. In, Sn, Al, Si, C, and One or more elements selected from the group consisting of Mg may be added in an amount of 1 to 15 mass %.

[0042] In FIG. 5(c), the surface of the active metal paste 18 printed on both sides of the ceramic substrate 17 is The metal plate 19 used for the metal circuit is made of copper, copper alloy, aluminum, etc. Examples include aluminum and aluminum alloys. Copper and copper alloys have high electrical conductivity. It is excellent for electrical circuits and has high thermal conductivity, making it excellent for heat dissipation of the semiconductor elements mounted on it. It is being done.

[0043] The active metal bonding method using active metal paste is a method of bonding an active metal paste to the surface of a ceramic substrate 17. The paste 18 is printed on the surface, and a metal plate 19 is placed on the surface. This is heated to 600 to 900°C. According to the active metal bonding method, the bonding strength between the ceramic substrate and the metal circuit can be increased to 50 It can be made to over MPa.

[0044] In FIG. 5(d), the surface of the metal plate 19 bonded by the bonding layer 181 formed by heating is etched. The etching resist 20 is printed. The printing is performed by a method such as screen printing. As mentioned above, the ceramic metal bonding substrate should be sucked onto the printing table. The screen is fixed by a tool such as a squeegee, and the etching resist is placed on the screen. By this, an etching resist 20 is printed on the surface of the ceramic substrate. The printing thickness of the resist for the coating is preferably 15 to 40 μm. The bonded substrate is heated in the atmosphere to dry the etching resist. In the case of a ceramic-metal bonded substrate with a metal plate bonded to it, one side is printed and an etching resist is applied. After drying, print the other side and dry the etching resist in the same way. The etching resist is heated if it is a heat-curable type, or irradiated with ultraviolet light if it is an ultraviolet-curable type. It hardens when irradiated.

[0045] In FIG. 5(e), the metal plate and the bonding layer are in an etched state. The printed and dried ceramic metal bonding substrate was then placed in a solution that dissolves (corrodes) the metal plate. In the same way, active metal paste is applied to form a circuit. The circuit is formed in the same way by immersing the substrate in a solution that dissolves the bonding layer formed by heating. At this time, the area printed with the etching resist is protected and does not dissolve.

[0046] In Figure 5(f), the etching resist has been removed. An element circuit 191 is formed on the back surface (bottom surface) of the substrate 190, and a heat sink 191 is formed on the back surface (bottom surface). In the case of organic solvent-based etching resists, etching is performed by immersing them in an organic solvent. The resist is then removed, and the ceramic circuit board 30 is thus formed.

[0047] In addition, the metal circuit surface is coated with a material selected from the group consisting of nickel (Ni), Ag, and gold (Au). As the metal thin film, a metal thin film containing one of the metals as a main component may be provided. By providing a thin metal film, corrosion resistance and solder wettability can be improved. It can improve the quality etc.

[0048] By the above-mentioned steps, a ceramic circuit board can be manufactured. The plate is suitable for a semiconductor device in which a semiconductor element is mounted on a metal circuit portion via a bonding layer. 6 is an example of a semiconductor device. In FIG. 6, 40 is a semiconductor device, 30 is a ceramic A circuit board, 41 is a semiconductor element, 42 is wire bonding, and 43 is a lead frame. In FIG. 6, a semiconductor is formed on the circuit portion of the ceramic circuit board 30 via a bonding layer (not shown). The adjacent circuit parts are electrically connected by wire bonding 42. The semiconductor device is not limited to such a structure. The bonding wires 41 and 42 may be provided in plural on the upper metal plate. In addition, a semiconductor element and wire bonding may be bonded to the metal plate on the bottom surface as required. In addition, metal terminals such as lead frames may be bonded to these circuit boards. The bonding layer for bonding the semiconductor element 41 is made of solder, brazing material, or the like. Therefore, lead-free solder is preferable. Solder has a melting point of 450°C or less. Brazing material refers to a material with a melting point of over 450°C. Also, materials with a melting point of 500°C or higher are called brazing materials. High-temperature brazing filler metals include those that contain Ag as the main component.

[0049] Furthermore, while semiconductor devices are becoming smaller, the amount of heat generated from the chip is increasing. For ceramic circuit boards that mount semiconductor elements, improving heat dissipation has become important. In addition, in order to improve the performance of semiconductor devices (semiconductor modules), ceramic circuit substrates are being developed. Multiple semiconductor devices can be mounted on the board. If it exceeds this limit, the resistance will change to a negative temperature coefficient. This causes thermal runaway, resulting in the semiconductor device being instantly destroyed. It is very effective to improve the reliability of the connection between the semiconductor element and the circuit part. The semiconductor device according to the present invention is used in automobiles (including electric vehicles), electric railway vehicles, industrial machinery, and air It can be used for PCU, IGBT, and IPM modules used in inverters such as As for automobiles, electric vehicles are becoming more and more popular. The more safety measures are implemented, the more safety can be improved for automobiles. The same applies to electric railway vehicles, industrial equipment, etc. is.

[0050] (Examples 1 to 8, Comparative Examples 1 to 6) 100 sheets of each ceramic substrate shown in Table 1 were prepared. The ceramic substrates were silicon nitride. The thermal conductivity of the silicon nitride substrate is 90 W / (m K ) and the three-point bending strength is 650MP. The thermal conductivity of the aluminum nitride substrate is 1 The thermal conductivity is 70W / (m·K) and the three-point bending strength is 300MPa. The size is 70mm long x 90mm wide. The thickness of the silicon nitride substrate is 0.32mm, and the thickness of the aluminum nitride substrate is 0.32mm. The thickness of the aluminum substrate was 0.635 mm. The metal plates shown in Table 1 were prepared. The metal plate measures 70mm long x 90mm wide x 0.5mm thick and is bonded to both sides. In Table 1, silicon nitride substrates are abbreviated as Si3N4 and aluminum nitride substrates as AlN. do.

[0051] Next, metal powders were prepared, which are the metal components of the paste shown in Table 1. The metal powders were silver-based powders. (Ag-Cu-Sn-Ti) and copper-based powder (Cu-Sn-TiH). The ratio of the silver-based powder is Ag 58% by mass, Cu 30% by mass, Sn 10% by mass, TiH 2% by mass. The ratio of the copper powder is Cu 68 mass%, Sn 20 mass%, and TiH 12 mass%. The average particle size of each metal powder is Ag 2 μm, Cu 1 μm, Sn 5 μm, and Ti 5 μm. Next, the organic components were dissolved in a solvent in 100% by mass of the metal powder. An active metal paste was prepared by adding 20% ​​by mass of the binder and kneading the mixture. While adding the paste, adjust the viscosity of the paste to within ±1% of the value in Table 1 using an E-type viscometer. Ta.

[0052] The active metal paste was printed on both sides of the ceramic substrate. The pattern on both sides was 110 mm long. × 170mm wide, and the distance from the periphery of the ceramic substrate to the pattern was 5mm. The active metal paste is fed to the printing paste supply device shown in FIG. 1 and the screen shown in FIG. Printing was performed using a printer under the conditions shown in Table 2 (distance to the injection nozzle, inner diameter of the supply pipe, container pressure). The timing for supplying the paste is 15 seconds (three times) before printing as shown in Figure 3(A). The discharge time was 5 seconds (1 time) for each print. After drying at 5°C for 5 minutes, the bottom surface was printed and dried in the same manner with a new screen.

[0053] Next, metal plates are placed on both sides of the ceramic substrate on which the paste has been printed and dried, and then heated. The bonding temperature was 820°C for silver-based paste (Ag-Cu-Sn-Ti) and 820°C for copper-based paste (Cu-Ti). In the case of the test piece (Cu-Sn-TiH), the temperature was 650°C. The bonding time for each was set to 10 minutes. and in a vacuum (1 x 10 -2 The bonding was performed at a temperature of 100 Pa or less.

[0054] Next, an etching resist was prepared as shown in Table 1. The etching resist was Hardening type etching resist (main components: copolymer resin, phenolic resin, oxide powder, butyrate) ether, etc.), UV-curable etching resist (main components: oligomer, monomer, While adding the solvent, measure the viscosity with an E-type viscometer until the viscosity is within ±1% of the value in Table 1. The paste viscosity was adjusted as follows. The pattern on the front side (circuit side) is 20mm long x 40mm wide, with 3 rows vertically and 3 rows horizontally. The distance from the periphery of the ceramic substrate to the pattern is 10 mm, and the distance between patterns is 20 The pattern on the bottom surface (back surface, heat dissipation surface) is 100mm long x 160mm wide, The distance from the periphery of the ceramic substrate to the pattern was set to 10 mm.

[0055] [Table 1]

[0056] Ceramic-metal bonded substrate with etching resist printed on it Metal plate and bonding layer After etching, the etching resist is removed to expose the circuit part on the top surface and the radiation part on the bottom surface. The heating section was formed. The formed ceramic circuit board was visually inspected. and PCBs where peeling of 0.5 mm or more was observed around the periphery of the metal plate in the heat dissipation area, and PCBs with a diameter of The substrates where swelling of 1 mm or more was observed were considered to have poor bonding and the rate of poor bonding was calculated. And the area that is not etched for 0.5 mm or more from the periphery of the metal plate of the heat sink (etching The area that remains unetched, and the area that is etched at least 0.5 mm from the periphery of the metal plate of the circuit and heat sink. Over-etched areas (defects due to etching of the circuit and heat dissipation areas), The metal plate is not etched in the areas where the ceramic substrate should be (between patterns, etc.). The remaining areas and the boards where etching was observed in the circuit and heat dissipation areas were The bonding failure rate and etching failure rate are shown in Table 2.

[0057] [Table 2]

[0058] In Examples 1 to 8, the bonding failure rate and etching failure rate did not occur or were low. This is because the active metal paste and etching resist were printed properly. In contrast, in Comparative Examples 1 to 6, the bonding failure rate and etching failure rate were high. , paste viscosity, resist viscosity, distance to injection port, and container size relative to the inner diameter B of the supply pipe The ratio of the pressure applied to the screen to the pressure applied to the screen (C / B) was outside the desired range. Due to the lean version, printing was not possible at the set position, or printing was not possible outside the set range. This is because the ink spread and caused printing unevenness.

[0059] As described above, the printing paste supply device according to the embodiment has fewer bonding defects and etching defects. Therefore, it is ideal for ceramic circuit boards.

[0060] Although several embodiments of the present invention have been illustrated above, these embodiments are presented as examples. These novel embodiments are not intended to limit the scope of the invention. It is possible to implement the invention in various other forms, and various modifications are possible without departing from the spirit of the invention. Various omissions, substitutions, and modifications may be made. The scope of the invention and its equivalents as defined in the claims are included in the scope and spirit of the invention. In addition, the above-described embodiments can be implemented in combination with each other. [Explanation of symbols]

[0061] 1...Feeding device 2...supply container, 21...pressure container, 22...paste container 3...Air injection pipe 4...Paste supply pipe 5...Pressure gauge 6...Switching valve 7...Ejection port 8...Paste 9...Screen printing machine 10...Screen version 11...Screen frame 12...Squeegee 13...Scraper 14...Ceramics-metal bonded substrate 15…Printing table 16... Mounting stand 17...Ceramic substrate 18...active metal paste, 181...bonding layer 19...metal plate, 191...metal circuit, 192...heat sink 20...Etching resist 30...Ceramic circuit board 40...Semiconductor device 41...Semiconductor element 42...Wire bonding 43...Lead frame 44...Resin mold

Claims

1. A printing paste supply device, A supply container for holding printing paste, a supply pipe having a switching valve, and a supply pipe for supplying the paste from the supply container. a mechanism for supplying printing paste to the ejection port using a feed pipe, The distance from the switching valve to the injection port is 0.2 m or more and 3 m or less, Ratio (C / B) of pressure C (MPa) applied to the container to the inner diameter B (mm) of the supply pipe A printing paste supplying device characterized in that:

2. The viscosity of the printing paste is 10 mPa.S or more and 250 Pa.S or less.

2. The printing paste supply device according to claim 1,

3. 10. The switching valve according to claim 1, wherein the switching valve is a diaphragm valve.

3. A printing paste supplying device according to claim 2.

4. The printing paste is an active metal paste or an etching resist.

3. The printing paste supplying device according to claim 1 or 2.

5. A printing machine comprising the printing paste supply device according to claim 1 or 2. Clean printing machine.

6. A screen printing machine comprising the printing paste supply device according to claim 3. 。

7. The screen printer according to claim 5 is used to print an active metal paste on a ceramic substrate. The metal plates are bonded by heating and then an etching resist is printed on the bonded metal plates. Manufacture of ceramic circuit boards on which metal circuits are formed by etching after printing method.

8. The ceramic substrate includes a silicon nitride substrate, an aluminum nitride substrate, and an aluminum oxide substrate. The ceramic circuit substrate according to claim 7, characterized in that it is one of the following substrates: Manufacturing method.

9. 8. The ceramic according to claim 7, wherein the metal circuit is made of copper or a copper alloy. A method for manufacturing a circuit board.

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