JP2009110989A - Manufacturing method of circuit board with metal fittings - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method suitable for obtaining a circuit board with metal fittings such that a terminal projecting from a ceramic substrate has neither deformation nor peeling. <P>SOLUTION: Disclosed is the manufacturing method of the circuit board 6 with metal fittings with the terminal including the stages of: preparing the ceramic substrate 1 and a ceramic support substrate 2; arranging the ceramic substrate 1 and ceramic support substrate 2 side by side, disposing metal plates 4 above and below them so that the metal plate 4 is sandwiched between them, and bonding the metal plates 4 to both principal surfaces of the ceramic substrate 1 and ceramic support substrate 2; forming the metal fittings by etching the bonded metal plates 4 so that the metal plate 4 bonded to one principal surface of the ceramic substrate 1 projects from the external side of the ceramic substrate 1; and removing the ceramic support substrate 2. Consequently, a metal fittings portion (terminal) of a metal circuit board 4a does not deform and the bonding reliability between the metal circuit board 4a and ceramic substrate 1 does not decreases either. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a circuit board with metal fittings such as terminals suitable for a power semiconductor module.

  In recent years, circuit boards formed by forming metal circuits and metal heat sinks on the front and back surfaces of ceramic substrates have been used in trains and electric vehicles that require large currents to flow as power semiconductor module boards. A power semiconductor module is formed by electrically connecting a semiconductor element and a passive element on a metal circuit by soldering, bonding wires, or the like. In addition, a terminal for connecting to an external circuit is joined to the metal circuit by soldering, ultrasonic bonding, or the like so as to protrude from the outer side of the ceramic substrate. In such power semiconductor modules, heat dissipation from the metal heat sink and heat dissipation from the terminal to the external circuit are generally performed, and the heat dissipation from the terminal is one of the important factors for the heat dissipation of the power semiconductor module. It is.

  In such a method of manufacturing a circuit board with metal fittings such as terminals, when the terminals are joined by soldering, the metal plate circuit is formed of copper or aluminum having good thermal conductivity, and the terminals are also formed of a material having good thermal conductivity. Even if it does, heat dissipation from a terminal will fall by pinching solder with inferior thermal conductivity than these in general, and will reduce the heat dissipation of the whole power semiconductor module. In addition, when bonding the terminal to the electrode by ultrasonic bonding, the area where the terminal and the electrode overlap with each other tends to be smaller, so the heat dissipation is likely to decrease. When strong ultrasonic waves are used to increase the area, or when the heating temperature is increased, sudden stress due to ultrasonic waves or stress due to rapid temperature changes is added to the joint between the ceramic substrate and the metal circuit board, There is a tendency that peeling and cracking are likely to occur at the joint and the strength of the joint is likely to decrease.

Therefore, as a method of integrally forming the terminal protruding from the outer side of the ceramic substrate with the metal circuit board, the metal plate protruding from at least one side of the ceramic substrate is joined to the ceramic substrate and protruded from the ceramic substrate by etching. As shown in the perspective view for each process in the method (A method) for forming the shaped terminal and FIGS. 4 (a) to 4 (e), both main surfaces of the ceramic substrate 11 are as large as the ceramic substrate 11. After forming the metal circuit board 14a with terminals on one main surface of the ceramic substrate 11 and the metal heat radiating plate 14b on the other main surface by joining and etching the metal plate 14 with the brazing material 13 or the like, the ceramic substrate There has been proposed a method (Method B) in which the terminal is protruded from the outer side of the ceramic substrate 11 by cutting out the end portion 11b of the eleven (see, for example, Patent Document 1).
JP 2003-218268 A

  However, in the case of the conventional method A, there is a problem that a portion protruding from the ceramic substrate is bent by the shower pressure of the etching solution after bonding.

  In the conventional method B, the portion protruding from the ceramic substrate is supported by the end portion 11b of the ceramic substrate 11 therebelow, so there is no problem of such deformation. However, when a terminal protruding on one main surface of the ceramic substrate 11 is joined, the end portion 11b of the ceramic substrate 11 is cut by dicing from the other main surface side, or along the dividing groove 11a formed on the ceramic substrate 11. Then, the end portion 11a of the ceramic substrate is cut off by bending toward the other main surface. When cutting by dicing, there is only a small gap between the surface of the metal circuit with terminal 14a on the side of the ceramic substrate 11 and one main surface of the ceramic substrate 11 that is about the thickness of the brazing material. If the height of the dicing saw is not precisely adjusted, the terminal is damaged by the dicing saw, and a burr-shaped sharp protrusion is generated on the terminal. When a high-voltage current is passed through a terminal having such a protrusion, it is easy to discharge from the terminal, and there is a problem that the withstand voltage in the insulation between the metal circuits 14a and 14a is lowered. Moreover, even if the burr is removed, the thickness of this portion is thinner than the other portions, so that it becomes easy to bend from this portion carelessly. Further, in the case of cutting along the dividing groove 11a to the other main surface side, if the joint between the terminal and the ceramic substrate 11 is close to the bent portion, the metal circuit board with terminal 14a and the ceramic substrate 11 are bent at the time of bending. In some cases, stress is applied to the joint and cracks may occur, and there is a problem in that the joint reliability of the metal circuit board with terminal 14a is lowered. Therefore, it is necessary to form the joint portion of the terminal-attached metal circuit board 14a with the ceramic substrate 11 away from the bent portion and to the inside of the ceramic substrate 11, and to make the protruding length of the terminal from the outer side of the ceramic substrate 11 the same. Attempting to do so would increase the circuit board 16 accordingly.

  In some cases, a metal circuit board 14a with terminals protruding on both main surfaces is provided, or the heat radiating plate 14b on one main surface is protruded from the outer side of the ceramic substrate 11. In this case, in the conventional method B, the line 11a to be cut by dicing intersects the protruding terminal and the heat sink 14b, so the end 11b of the ceramic substrate is cut off without cutting the terminal and the heat sink. It is not possible. For this reason, it is cut along the dividing groove 11a, but the brazing material thickness for joining the terminals and the heat sink 14b on the ceramic substrate 11 side and one main surface of the ceramic substrate 11 is cut. Since there is only a small interval, if the end 11b of the ceramic substrate 11 is bent so as to be cut off, it will hit the protruding terminal or the heat sink, so that the terminal or the heat sink may be bent, the metal circuit board 14a with a terminal or the heat dissipation There is a problem that a large stress is applied to the joint between the plate 14b and the ceramic substrate 11 and the metal circuit board 14a with terminal and the heat sink 14b are peeled off.

  The present invention has been devised in view of the above problems, and its purpose is to produce a circuit board with metal fittings suitable for obtaining a circuit board with metal fittings in which terminals protruding from the ceramic substrate are not deformed or peeled off. Is to provide a method.

  The method of manufacturing a circuit board with a metal fitting according to the present invention includes a step of preparing a ceramic substrate and a ceramic support substrate, and the ceramic substrate and the ceramic support substrate are arranged side by side, and metal plates are arranged vertically so as to sandwich them. Bonding the metal plate to both main surfaces of the ceramic substrate and the ceramic support substrate; and a shape in which the metal plate bonded to at least one main surface of the ceramic substrate protrudes from the outer side of the ceramic substrate; As described above, the method includes a step of etching the joined metal plates to form a metal fitting, and a step of removing the ceramic support substrate.

  The method for manufacturing a circuit board with a metal fitting according to the present invention is the above manufacturing method, wherein the length from the joint portion between the ceramic substrate and the metal plate on one main surface side to the joint portion between the ceramic support substrate and the metal plate is The length from the joint portion between the ceramic substrate and the metal plate on the other main surface side to the joint portion between the ceramic support substrate and the metal plate is the same.

  The method of manufacturing a circuit board with a metal fitting according to the present invention is the above manufacturing method, wherein the ceramic substrate and the ceramic support are provided between the step of joining the metal plates and the step of etching the metal plate to form the metal fittings. It includes a step of filling a space between the substrate and the resin.

  The method for manufacturing a circuit board with a metal fitting according to the present invention includes a connecting metal plate bonded to both the ceramic substrate and the ceramic support substrate in the manufacturing method, wherein the metal plate is etched to form a metal fitting. Forming, and then removing the connecting metal plate.

  According to the method for manufacturing a circuit board with metal fittings with a terminal according to the present invention, a step of bonding a metal plate so as to sandwich a ceramic substrate and a ceramic support substrate arranged side by side, and bonding to at least one main surface of the ceramic substrate. Since the metal plate includes a step of etching the joined metal plate to form a metal fitting so that the metal plate has a shape protruding from the outer side of the ceramic substrate, a pre-divided ceramic substrate is used. Without cutting the ceramic substrate, the metal support such as a terminal can be easily protruded from the outer side of the ceramic substrate by removing the ceramic support substrate. Therefore, by not performing dicing or bending when cutting the ceramic substrate, the metal fittings are not damaged, and no force is applied to the metal fittings or the joint between the metal fittings and the ceramic substrate. Even if a metal circuit for passing a current is formed at a high density, the withstand voltage between the metal circuits is not lowered, and the metal fitting is not deformed and the bonding reliability between the metal fitting and the ceramic substrate is not lowered. In addition, since the joint between the metal fitting and the ceramic substrate can be formed at the end of the ceramic substrate, the ceramic substrate and the circuit substrate can be reduced in size.

  In addition, according to the method for manufacturing a circuit board with a metal fitting of the present invention, the length from the joint portion between the ceramic substrate and the metal plate on one main surface side to the joint portion between the ceramic support substrate and the metal plate, and the other main surface side When the length from the joint between the ceramic substrate and the metal plate to the joint between the ceramic support substrate and the metal plate is the same, the metal plate is restrained by the ceramic substrate and the ceramic support substrate when cooled after joining. Since the length of the portion that shrinks without any difference between the upper and lower sides of the two ceramic substrates, the amount of shrinkage of the metal plate is the same at the upper and lower sides, and the metal plate protruding from the ceramic substrate is not deformed due to the difference in shrinkage. . As a result, it is possible to manufacture a circuit board that is more excellent in dimensional accuracy of metal fittings such as terminals protruding from the outer side of the ceramic board.

  Further, according to the method for manufacturing a circuit board with a metal fitting of the present invention, between the step of joining the metal plate and the step of etching the metal plate to form the metal fitting, between the ceramic substrate and the ceramic support substrate. When including the step of filling with resin, the etching liquid is prevented from flowing into the back surface of the metal fitting from the gap between the ceramic substrate and the ceramic support substrate, so that the dimensional accuracy of the metal fitting can be improved and the metal fitting It is possible to prevent problems such as a partial decrease in strength and an increase in electrical resistance due to a part of the film becoming thinner.

  Further, according to the method for manufacturing a circuit board with a metal fitting of the present invention, when the connection metal plate joined to both the ceramic substrate and the ceramic support substrate is formed and then the connection metal plate is removed together with the ceramic support substrate. Since the ceramic support substrate is fixed to the lower surface of the metal fitting even after the metal fitting and the ceramic support substrate are separated by etching processing, the deformation of the metal fitting due to the shower pressure of etching processing or rattling during transportation is suppressed. Can do.

  Next, the manufacturing method of the circuit board with metal fittings of this invention is demonstrated in detail, referring attached drawing.

  FIG. 1A to FIG. 1E are perspective views for each process showing an example of an embodiment of a method for manufacturing a circuit board with a metal fitting according to the present invention. In FIG. 1, 1 is a ceramic substrate, 2 is a ceramic support substrate, 3 is a bonding material paste, 3a is a bonding material, 4 is a metal plate, 4a is a metal circuit board with metal fittings formed by etching the metal plate 4, 4b Is a heat sink formed by etching the metal plate 4, 5 is a resist, and 6 is a circuit board with metal fittings.

  The manufacturing method of the circuit board 6 with a metal fitting according to the present invention includes a step of preparing the ceramic substrate 1 and the ceramic support substrate 2, and the ceramic substrate 1 and the ceramic support substrate 2 arranged side by side, and the metal plate 4 is vertically moved so as to sandwich them. And the step of bonding the metal plate 4 to both main surfaces of the ceramic substrate 1 and the ceramic support substrate 2, and the metal plate 4 bonded to at least one main surface of the ceramic substrate 1 from the outer side of the ceramic substrate 1. It includes a step of etching the joined metal plate 4 to form a metal fitting so as to have a protruding shape, and a step of removing the ceramic support substrate 2.

  Accordingly, since the ceramic substrate 1 and the ceramic support substrate 2 which are divided in advance are used, the metal substrate such as a terminal can be easily attached by removing the ceramic support substrate 2 without cutting the ceramic substrate 1. It can protrude from the outer side of 1. Dicing or bending is not performed to cut the ceramic substrate 1, but the metal part (terminal) of the metal plate circuit board 4 a is damaged, or the metal part (terminal) of the metal circuit board 4 a or the metal circuit board 4 a and the ceramic substrate 1 are Since no force is applied to the joint portion, the withstand voltage between the metal circuit boards 4a does not decrease even if the metal circuit board 4a for flowing a high voltage and large current is formed at a high density, and the metal circuit board 4a. The metal parts (terminals) are not deformed, and the joining reliability between the metal circuit board 4a and the ceramic substrate 1 is not lowered. Moreover, since the junction part of the metal circuit board 4a with a metal fitting and the ceramic substrate 1 can be formed in the edge part of the ceramic substrate 1, the ceramic substrate 1 and the circuit board 6 with a metal fitting can be reduced in size.

  In the example shown in FIG. 1, the metal fitting protruding from the outer side of the ceramic substrate 1 is formed integrally with the metal circuit board 4a formed on the upper surface of the ceramic substrate 1, and the terminal used for connection with an external circuit or Used as a heat sink. The metal fitting may be formed not connected to the metal circuit board 4a, and in this case, it may be used as a fixing plate for fixing the heat radiating plate or the circuit board 6 with the metal fitting to an external component or device. Moreover, although the heat sink 4b on the lower surface of the ceramic substrate 1 does not protrude from the outer side of the ceramic substrate 1, it is formed as a metal fitting protruding from the outer side of the ceramic substrate 1 to increase the heat dissipation area to the outside. The heat may be radiated more efficiently, or a through hole may be formed in the protruding portion and fixed by screwing. Further, a metal circuit board 4 a with terminals similar to the upper surface may be formed on the lower surface of the ceramic substrate 1.

  2A is a cross-sectional view showing an example of a cross section taken along line AA in FIG. 1B, and FIG. 2B is a cross-sectional view showing an example different from FIG. 2A. It is.

  Moreover, the manufacturing method of the circuit board 6 with a metal fitting of this invention is the ceramic support substrate 2 and the metal plate 4 from the junction part of the ceramic substrate 1 and the metal plate 4 of one main surface side like the example shown in FIG. 2 (indicated by L1 in FIG. 2) and the length from the junction between the ceramic substrate 1 and the metal plate 4 on the other main surface side to the junction between the ceramic support substrate 2 and the metal plate 4 It is preferable to make the same (indicated by L2 in FIG. 2). Thus, when cooled after joining, the lengths of the ceramic substrate 1 and the ceramic support substrate 2 in which the lengths of the metal plates 4 and 4 contracted without being restrained by the ceramic substrate 1 and the ceramic support substrate 2 are aligned. Therefore, the amount of contraction of the metal plates 4 and 4 is the same at the top and bottom, and the metal plates 4 and 4 protruding from the ceramic substrate 1 are not deformed due to the difference in contraction. As a result, it is possible to manufacture the circuit board 6 with metal fittings that is more excellent in dimensional accuracy of metal fittings such as terminals protruding from the outer side of the ceramic substrate 1. Even if the positions of the upper and lower joints are the same as in the example shown in FIG. 2 (a), or the positions of the upper and lower joints are different as in the example shown in FIG. 2 (b). This is the same even if

  Moreover, the manufacturing method of the circuit board 6 with metal fittings of this invention is a resin between the ceramic substrate 1 and the ceramic support substrate 2 between the process of joining the metal plate 4, and the process of etching the metal plate 4. It is preferable to include the step of filling. This prevents the etchant from flowing from the gap between the ceramic substrate 1 and the ceramic support substrate 2 to the back surface of the metal fitting, so that the dimensional accuracy of the metal fitting can be improved and a part of the metal fitting can be obtained. Therefore, it is possible to prevent problems such as a partial decrease in strength and an increase in electrical resistance due to thinning.

  FIGS. 3A to 3E are perspective views for each step similar to FIG. 1 showing an example of an embodiment of a method for manufacturing a circuit board 6 with a metal fitting according to the present invention. In FIG. 3, 4 c is a connection metal plate, 1 a is a dividing groove, and 1 c is an end of the ceramic substrate 1.

  Moreover, the manufacturing method of the circuit board 6 with metal fittings of this invention is the connection metal joined to both the ceramic board | substrate 1 and the ceramic support board | substrate 2 in the process of etching the metal plate 4 like the example shown in FIG. It is preferable to include a step of forming the plate 4c and then removing the connecting metal plate 4c. Thereby, even after the metal fitting and the ceramic support substrate 2 are separated by etching, the ceramic support substrate 2 is fixed to the lower surface of the metal fitting. Deformation can be suppressed.

  In the example shown in FIG. 3, the connection metal plate 4 c is formed in a frame shape so as to overlap two outer peripheral portions of the ceramic substrate 1 and the ceramic support substrate 2, but straddles the ceramic substrate 1 and the ceramic support substrate 2. Therefore, one or more rod-shaped members may be used.

  In the example shown in FIG. 3, the step of removing the connection metal plate 4 c is performed by dividing and cutting the ceramic substrate 1 along the division grooves 1 c previously provided in the ceramic substrate 1 and connecting the connection metal plate 4 c. This is done by removing the end 1b of the ceramic substrate 1 together. In addition, the ceramic substrate 1 may be cut by dicing or laser at the same position without providing the dividing groove 1a. When there may be a connection metal plate 4c around the metal circuit board 4a and the heat sink 4b, the connection metal plate 4c is cut without cutting the ceramic substrate 1, and only a part thereof is ceramic support substrate 2. It may be removed together.

  Hereinafter, each process of the manufacturing method of the circuit board with a metal fitting of the present invention is explained in detail.

  First, the ceramic substrate 1 and the ceramic support substrate 2 are prepared.

  The ceramic substrate 1 is, for example, a substantially rectangular plate-like body, and functions as a support member that supports the metal circuit plate 4a in the circuit board 6 with metal fittings. Such a ceramic substrate 1 is formed of an electrically insulating material such as an aluminum oxide sintered body, a mullite sintered body, a silicon carbide sintered body, an aluminum nitride sintered body, or a silicon nitride sintered body. For example, a thickness of 0.1 mm to 0.7 mm is used.

  The ceramic substrate 1 is preferably a silicon nitride-based sintered body that has high strength and can be thinned. In this case, the thickness of the insulating substrate 1 is more preferably 0.1 mm to 0.4 mm. If the ceramic substrate 1 is thinner than 0.1 mm, the strength as a support tends to be insufficient, and the warp tends to increase when bonded to the metal plate 4. If the thickness exceeds 0.4 mm, the heat of the ceramic substrate 1 is increased. Since the resistance is larger than that of the metal circuit board 4a and the heat sink 4b, the heat dissipating property tends to be lowered.

  If the ceramic substrate 1 is made of, for example, a silicon nitride sintered body, a suitable organic binder, plasticizer, and solvent are added to and mixed with raw material powders such as silicon nitride, aluminum oxide, magnesium oxide, yttrium oxide, and the like. A ceramic green sheet (ceramic green sheet) is formed by adopting the doctor blade method and calendar roll method, which are well-known in the past, and then the ceramic green sheet is punched appropriately to form a predetermined shape. Accordingly, a plurality of sheets are laminated to form a molded body, and thereafter, the molded body is fired at a temperature of 1600 to 2000 ° C. in a non-oxidizing atmosphere such as a nitriding atmosphere. When the dividing groove 1a is provided on the ceramic substrate 1 as in the example shown in FIG. 3, it can be provided by forming a groove by pressing a cutter blade against a molded body in which ceramic green sheets are laminated. After the ceramic substrate 1 is manufactured, grooves may be formed using a laser or a dicing apparatus.

  The ceramic support substrate 2 is preferably the same material and the same thickness as the ceramic substrate 1 in order to prevent warping and bending of the metal plate 4 in a subsequent process. If the ceramic support substrate 2 is produced with the same thickness of the ceramic green sheet by the same method as the ceramic substrate 1, the ceramic substrate 1 and the ceramic support substrate 2 can have the same thickness. Even if the two companies have different thicknesses, the same thickness can be obtained by polishing. However, if the ceramic substrate 1 and the ceramic support substrate 2 are formed by cutting one ceramic substrate, the ceramic substrate 1 and the ceramic support are formed. The thickness of the portion facing the substrate 2 can be easily made the same, which is preferable.

  Next, the ceramic substrate 1 and the ceramic support substrate 2 are arranged apart from each other, and the metal plate 4 is vertically arranged so as to sandwich them, and the metal plate 4 is joined to both main surfaces of the ceramic substrate 1 and the ceramic support substrate 2. .

  In the example shown in FIGS. 1 and 3, the metal fitting protrudes from one side of the ceramic substrate 1, but the metal fitting may protrude from two or more sides of the ceramic substrate 1. In this case, the ceramic support substrate 2 may be disposed outside all sides from which the metal substrate 1 is protruded. The number of ceramic support substrates 2 may be a number corresponding to the number of sides from which the metal fittings of the ceramic substrate 1 are projected, or may be a single piece. For example, when protruding metal fittings from two adjacent sides, two ceramic support substrates 2 may be arranged on each side, or one L-shaped ceramic support substrate 2 may be arranged. .

  When the ceramic substrate 1 and the ceramic support substrate 2 are arranged so that their end faces are in contact with each other and the metal plates 4 are arranged above and below the ceramic substrate 1, the ceramic substrate 1 and the ceramic support substrate 2 are thermally expanded when heated from room temperature to the bonding temperature. However, since the ceramic substrate 1 and the ceramic support substrate 2 are usually placed on the metal plate 4 that thermally expands larger than that, the metal plate 4, the ceramic substrate 1, and the ceramic support are between them at the bonding temperature. They are separated from the substrate 2 by a difference in thermal expansion. When the ceramic substrate 1 and the ceramic support substrate 2 are integrated as in the prior art, thermal stress is generated during cooling between the joined metal plate 4 and the ceramic plate 1. When the ceramic substrate 1 and the ceramic support substrate 2 are divided into two substrates as described above, the thermal stress generated between the joints causes the metal plate 4 to contract and the ceramic substrate 1 and the ceramic support substrate 2 to contract. Since the space between them is absorbed, the bonding reliability between the metal plate 4 and the ceramic substrate 1 is improved.

  When the ceramic substrate 1, the ceramic support substrate 2, or the metal plate 4 is heated and the positions of the ceramic substrate 1, the ceramic support substrate 2, and the metal plate 4 are shifted due to the material and dimensions of the metal plate 4 and the type and thickness of the bonding material paste 3. In order to reliably provide a space between the ceramic substrate 1 and the ceramic support substrate 2 at the time of bonding, it is preferable to arrange the ceramic substrate 1 and the ceramic support substrate 2 apart from each other before bonding.

  The metal plate 4 is made of copper, aluminum, or the like, and is formed into a plate shape having a thickness of, for example, 0.1 mm to 1 mm by subjecting a copper or aluminum ingot (lumb) to a conventionally known metal processing method such as a rolling method or a punching method. It is a thing.

  When the metal plate 4 is made of copper, it is preferable to use oxygen-free copper. When oxygen-free copper is used, the surface of the metal plate 4 is not oxidized by oxygen present in the copper, and the wettability with the bonding material 3a becomes better. Bonding becomes strong.

  The thickness of the metal plate 4 is preferably 0.3 mm to 0.5 mm. If the thickness of the metal plate 4 is less than 0.3 mm, the amount of heat generated tends to increase when a large current is passed. When the thickness of the metal plate 4 exceeds 0.5 mm, the stress applied to the ceramic substrate 1 tends to increase due to the difference in thermal expansion coefficient between the metal plate 4 and the ceramic substrate 1, so the pattern of the front and back metal plates 4 is increased. The warp of the ceramic substrate 1 tends to increase due to the difference in shape.

  The method of joining the ceramic substrate 1 and the ceramic support substrate 2 to the metal plate 4 is to form a metallized layer on the main surfaces of the ceramic substrate 1 and the ceramic support substrate 2 in advance, and then connect the metallized layer and the metal plate 4 to each other. There are a method of bonding with a brazing material and a method of directly bonding the ceramic substrate 1 and the ceramic support substrate 2 to the metal plate 4 using an active metal in addition to the brazing material without forming a metallized layer.

  In the former method, on the metallized layer on the ceramic substrate 1 and the ceramic support substrate 2, for example, a silver brazing material (silver: 72% by weight-copper: 28% by weight) or an aluminum brazing material (aluminum: 88% by weight-silicon). : 12% by weight) of the bonding material paste 3 as a main component is applied and dried, and the metal plates 4 are arranged up and down so as to sandwich them, and in vacuum or in a neutral / reducing atmosphere at a predetermined temperature (silver) Heating is performed at about 800 ° C for brazing material, and about 600 ° C for aluminum brazing material, and the organic solvent and solvent in the bonding material paste 3 are evaporated and the brazing material (bonding material 3a) is melted. Is done. Instead of the application of the bonding material paste 3, a sheet-shaped bonding material 3a may be placed.

  In order to form a metallized layer on the ceramic substrate 1 and the ceramic support substrate 2, tungsten (W), molybdenum (Mo), manganese (Mn) or a mixture thereof is mixed in the manufacturing process of the ceramic substrate 1 and the ceramic support substrate 2 described above. The applied metal paste may be applied to the ceramic green sheet in a predetermined pattern shape by a coating method such as a screen printing method and fired simultaneously with the ceramic green sheet. Alternatively, a metal paste may be applied in the same manner on the ceramic substrate 1 and the ceramic support substrate 2 and baked.

  It should be noted that the metallized layer is formed by depositing a metal having good conductivity such as nickel and gold and having good corrosion resistance and wettability with the bonding material 3a to a thickness of 1 to 20 μm by plating. The oxidative corrosion of the layer can be effectively prevented, and the bonding of the metallized layer and the metal plate 4 by the bonding material 3a can be made extremely strong.

In the latter method, a bonding material paste 3 containing an active metal is applied to the main surfaces of the ceramic substrate 1 and the ceramic support substrate 2 by a known screen printing method and dried, and the metal plate 4 is moved up and down so as to sandwich them. Place the metal plate 4 at a predetermined temperature (approximately 800 ° C for silver brazing material and approximately 600 ° C for aluminum brazing material) in a non-oxidizing atmosphere while applying a load of 10 to 100 g per cm ² By heating, the organic solvent and solvent in the bonding material paste 3 are evaporated and melted, and the upper and lower surfaces of the ceramic substrate 1 and the ceramic support substrate 2 are bonded to the metal plate 4 through the bonding material 3a.

  The bonding material paste 3 in this case is composed of 95 to 98% by mass of the same brazing filler metal powder as described above, 2 to 5% by mass of titanium (Ti), zirconium (Zr), hafnium (Hf), and hydrides thereof. A suitable organic solvent and a solvent are added to and mixed with an active metal brazing material composed of at least one active metal powder.

  In any method, the bonding material paste is formed on the ceramic substrate 1 and the ceramic support substrate 2 or the metallized layer thereon using, for example, a conventionally known screen printing method in a predetermined pattern shape with a thickness of, for example, 10 to 50 μm. 3 is printed and applied, and dried at a temperature of about 120 ° C., whereby a bonding material 3 a for bonding the metal plate 4 to the surfaces of the ceramic substrate 1 and the ceramic support substrate 2 is supplied.

  In the example shown in FIGS. 1 and 3, the bonding material paste 3 is applied to the shape of the metal circuit board 4a on the upper surface of the ceramic substrate 1 and to the shape of the heat sink 4b on the lower surface, although not visible in the drawing. . On the upper surface of the ceramic support substrate 2, the bonding material paste 3 is applied to the tip of the metal circuit board 4 a protruding from the outer side of the ceramic substrate 1 to the tip. Since the bonding material paste 3 is not applied to the lower surface of the portion protruding from the outer side of the ceramic substrate 1, the metal fitting is not bonded to the ceramic support substrate 2, so that the ceramic support substrate 2 can be easily removed. Can do. The bonding material paste 3 is also applied to the lower surface of the ceramic support substrate 2 at the same position as the upper surface in plan view. This is because if the metal plate 4 is bonded only to the upper surface of the ceramic support substrate 2, the metal plate 4 may be warped due to the difference in thermal expansion coefficient between the metal plate 4 and the ceramic support substrate 2 when cooled after bonding.

  In the example shown in FIG. 3, the bonding material paste 3 for connecting the connection metal plate 4 c is applied to the outer peripheral portions of the ceramic substrate 1 and the ceramic support substrate 2. The length from the junction between 1 and the metal plate 4 to the junction between the ceramic support substrate 2 and the metal plate 4, and the ceramic support substrate 2 and the metal from the junction between the ceramic substrate 1 and the metal plate 4 on the other main surface side Since it is preferable that the length to the joint portion with the plate 4 is the same, the distance between the connection portions of the connection metal plate 4c and each of the ceramic substrate 1 and the ceramic support substrate 2 should be the same. preferable. For example, in the example shown in FIG. 3A, the end on the ceramic substrate 1 side of the pattern of the bonding material paste 3 for connecting the ceramic support substrate 2 and the connection metal plate 4c is bonded to the tip of the metal fitting. It is preferable to match the pattern of the bonding material paste 3 to be made.

Further, when a metal having a larger thermal expansion coefficient than the ceramic substrate 1 and the ceramic support substrate 2 is used for the metal plate 4, even if the end surfaces of the ceramic substrate 1 and the ceramic support substrate 2 are first brought into contact with each other, As described above, when the bonding material 3a is melted and hardened at about 800 ° C., the ceramic substrate 1 and the ceramic support substrate 2 are separated from each other. For example, an alumina sintered body substrate (thermal expansion coefficient αa: 7 × 10 ⁻⁶ / ° C.) is used as the ceramic substrate 1 and the ceramic support substrate 2, and copper (thermal expansion coefficient αc: 17 × 10 ⁻⁶ / 8) is used as the metal plate 4. When the bonding material paste 3 is applied and the ceramic substrate 1 and the ceramic support substrate 2 are arranged so that the end faces are in contact with each other, and the metal plate 4 is vertically arranged so as to sandwich them (room temperature Tr: 20) If the distance L0 between the bonding material pastes 3 at 50 ° C. is 50 mm, L = L0 × ΔT between the ceramic substrate 1 and the ceramic support substrate 2 at the temperature at which the bonding material 3a is hardened (Tm: 800 ° C.). A gap of ΔΔα = L0 × (Tm−Tr) × (αc−αa) = 0.39 mm is formed. As described above, this gap can relieve the thermal stress generated during cooling after bonding, but in consideration of misalignment between the ceramic substrate 1 and the ceramic support substrate 2 and the metal plate 4 when heated, In the case where the ceramic substrate 1 and the ceramic support substrate 2 are separated from each other in advance before bonding (a gap is provided between them), a gap is formed even after cooling.

  After the metal plate 4 is joined and before the metal plate 4 is etched, in order to prevent the etchant from flowing into the back surface of the metal fitting from the gap, the resin is filled in the gap. A resist resin paste may be injected into the substrate. It is preferable to use a resist resin used at the time of subsequent etching because the resin filled in the gap can be removed at the same time when the resist film after the etching is peeled off. The resin in this case is not limited to the same resin as the resist resin, but may be any resin that can be removed by the resist film stripping solution.

  Resin is not poured under the connection metal plate 4c, and the thickness of the portion of the connection metal plate 4c that overlaps the gap between the ceramic substrate 1 and the ceramic support substrate 2 is reduced to remove the subsequent connection metal plate 4c. You may make it easy to cut | disconnect in a process.

  Next, the bonded metal plate 4 is etched to form a metal fitting so that the metal plate 4 bonded to at least one main surface of the ceramic substrate 1 protrudes from the outer side of the ceramic substrate 1.

  In the etching process, as shown in FIG. 1C, a resist film 5 having a pattern shape of the metal circuit board 4a, the heat radiating plate 4b, or the connection metal plate 4c is formed on the surface of the metal plate 4, and the metal plate 4 For example, the etching solution is sprayed on the shower.

  The resist film 5 is formed by a method of attaching a film-like resist film or a method of applying and curing a liquid resist ink. In either method, there is a method in which a resist resin film is formed on the entire surface of the metal plate 4 and exposed to ultraviolet rays or the like through a mask and cured to remove uncured portions, thereby processing into a desired pattern shape. In the case of a method of applying a resist ink, a method of printing a resist ink in a pattern shape may be used, and this method is preferable because it is easy to form a resist film 5 having a pattern shape.

  The resist film 5 is made of a resin that does not dissolve or peel off by the etchant during the etching process of the metal plate 4, and includes a resin containing an acrylic oligomer, an acrylic monomer, and an inorganic pigment. Some are curable.

  In the example shown in FIGS. 1 and 3, the surface of the metal plate 4 on the upper surface of the ceramic substrate 1 is in the shape of the metal circuit board 4a, and the surface of the metal plate 4 on the lower surface of the ceramic substrate 1 is not visible in the drawings. The resist film 5 is formed by printing and applying a resist ink to the shape of the heat radiating plate 4b using a conventionally known screen printing method and drying at 150 ° C., for example.

  Etching of the metal plate 4 is performed by arranging the joined body of the metal plate 4 on which the resist film 5 is formed, the ceramic substrate 1 and the ceramic support substrate 2 in a jig so as not to move unnecessarily. In the case of comprising, for example, shower etching is performed from the upper and lower surfaces using a ferric chloride solution.

  In the example shown in FIGS. 1 and 3, the bonding material 3a formed on the ceramic support substrate 2 and the metal circuit 4a are separated by etching. When the connection metal plate 4c is formed as in the example shown in FIG. 3, the ceramic substrate 1 and the ceramic support substrate 2 are kept aligned without being separated during the etching process. However, there is a ceramic support substrate 2 on the lower surface, and the process can proceed without protruding, and the metal fittings such as terminals are displaced by the pressure of the liquid flow of shower etching and the positions of the ceramic substrate 1 and the ceramic support substrate 2 are shifted. Deformation of the metal fitting caused by hitting is difficult to occur.

  Note that the bonding material 3a and the metal circuit 4a formed on the ceramic support substrate 2 are not necessarily separated by etching. For example, the resist film 5 shown in FIG. 1C overlaps with the bonding material 3a formed on the upper surface of the ceramic support substrate 2 in a top view, that is, a portion protruding from the ceramic substrate 1 of the metal circuit board 4a (metal fitting). When the resist film 5 is formed to be longer and etched, the tip of the portion of the metal circuit board 4a (metal fitting) protruding from the ceramic substrate 1 is bonded to the ceramic support substrate 2 via the bonding material 3a. Become. In this case, a resist film 5 is also formed on the surface of the metal plate 4 on the lower surface of the ceramic support substrate 2 so as to overlap with the joined portion in plan view, and a portion of the metal plate 4 below the resist film 5 is formed. It is better to remain in a joined state. In this manner, even if the pressure of the etching solution is applied to the portion of the metal circuit board 4a (metal fitting) protruding from the ceramic substrate 1 in the etching process, the metal support plate 2 is supported by the metal substrate 4a (metal fitting). It becomes difficult.

  After the etching, the resist film 5 is peeled off. The resist film 5 is peeled off by shower peeling or immersion brushing using, for example, an alkaline aqueous solution such as an aqueous sodium hydroxide solution or an organic solvent such as acetone.

  Next, the ceramic support substrate 2 is removed. In the example shown in FIG. 1, since the metal circuit 4a and the ceramic support substrate 2 are already separated, the metal circuit 4a and the like can be easily removed. The attached circuit board 6 can be obtained. When the frame-shaped connecting metal plate 4c is formed as in the example shown in FIG. 3, the ceramic substrate 1 is divided into the circuit board 6 with metal fittings and the end portion 1c of the ceramic substrate 1 along the dividing groove 1a. The ceramic support substrate 2 connected by the connection metal plate 4c is removed. Alternatively, after cutting the frame-shaped connecting metal plate 4c and removing the ceramic support substrate 2, the ceramic substrate 1 may be divided along the dividing groove 1a to remove the end 1c of the ceramic substrate 1. It is easier to divide the ceramic substrate 1 along the dividing groove 1a if the connecting metal plate 4c bonded on the ceramic substrate 1 is cut in advance on the dividing groove 1a.

  On the surface of the metal circuit board 4a and the heat sink 5a of the circuit board 6 with the metal fitting, a film having good conductivity such as nickel plating and having good corrosion resistance and good wettability with solder is formed as necessary. In addition, the electrical connection between the metal circuit board 4a and the external electric circuit can be improved, and the electronic component can be firmly bonded to the metal circuit board 4a via solder.

  Note that the present invention is not limited to the above-described best mode, and various modifications may be made without departing from the scope of the present invention. For example, a metal plate 4 or a metal circuit board 4a is disposed between two ceramic substrates 1 and 1 and bonded, and a metal circuit board 4a or a heat sink 5 is bonded to the upper and lower sides thereof to form a multilayer structure. The heat dissipation may be increased or the size may be reduced.

(A)-(e) is a perspective view which shows an example of embodiment of the manufacturing method of the circuit board with a metal fitting of this invention, respectively. (A) And (b) is sectional drawing which shows an example of embodiment of the manufacturing method of the circuit board with a metal fitting of this invention, respectively. (A)-(e) is a perspective view which shows an example of embodiment of the manufacturing method of the circuit board with a metal fitting of this invention, respectively. (A)-(e) is a perspective view which shows an example of embodiment of the manufacturing method of the conventional circuit board with a metal fitting, respectively.

Explanation of symbols

1: Ceramic substrate 1a: Dividing groove 2: Ceramic support substrate 3: Bonding material paste 3a: Bonding material 4: Metal plate 4a: Metal circuit board 4b: Heat sink 4c: Connection metal plate 5: Resist film 6: Circuit board with metal fittings

Claims (4)

Preparing a ceramic substrate and a ceramic support substrate;
Arranging the ceramic substrate and the ceramic support substrate horizontally, arranging the metal plates vertically so as to sandwich them, and bonding the metal plate to both main surfaces of the ceramic substrate and the ceramic support substrate;
Etching the joined metal plate to form a metal fitting so that the metal plate joined to at least one main surface of the ceramic substrate protrudes from the outer side of the ceramic substrate;
And a step of removing the ceramic support substrate. The length from the joint portion between the ceramic substrate on the one main surface side and the metal plate to the joint portion between the ceramic support substrate and the metal plate, and the joint portion between the ceramic substrate and the metal plate on the other main surface side 2. The method for manufacturing a circuit board with metal fittings according to claim 1, wherein the length from the ceramic support substrate to the joint portion of the metal plate is the same. A step of filling the space between the ceramic substrate and the ceramic support substrate with a resin between the step of joining the metal plates and the step of etching the metal plates to form a metal fitting is characterized. The manufacturing method of the circuit board with a metal fitting of Claim 1 or Claim 2. The step of etching the metal plate to form a metal fitting includes the step of forming a connection metal plate joined to both the ceramic substrate and the ceramic support substrate, and then removing the connection metal plate. The method for manufacturing a circuit board with a metal fitting according to any one of claims 1 to 3.

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