JP2008010520A - Substrate for power module, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for power module which can quickly radiate heat from a semiconductor element by making a copper plate in a necessary region thick without breaking a ceramic substrate, and to provide its manufacturing method. <P>SOLUTION: The substrate 10 for power module is provided with a circuit copper plate 12 wherein a mounting copper plate 13 is provided on one main surface of a ceramic substrate 11 to mount a semiconductor element, and an all-overlaying copper plate 14 which is provided on the other surface thereof to radiate heat from the semiconductor element. In this case, a first additional overlapping copper plate 15 smaller in external shape than the mount copper plate 13 is bonded on the mount copper plate 13, and a second additional overlapping copper plate 16 smaller in external shape than the all-overlaying copper plate 14 is bonded on the all-overlaying copper plate 14. In addition, steps 17 and 17a are provided between the outer periphery of the first additional overlapping copper plate 15 and the mount copper plate 13, and between the second additional overlapping copper plate 16 and the all-overlaying copper plate 14, respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power module substrate and a method for manufacturing the same. More specifically, a copper plate is bonded to each of both main surfaces of a ceramic substrate, and heat generation when a semiconductor element that generates a large amount of heat is mounted is quickly generated. The present invention relates to a power module substrate that can dissipate heat and a method of manufacturing the same.

  Conventionally, a semiconductor element that generates high heat, such as a power transistor with higher power, higher speed, and higher integration, can be mounted, and heat generated from the semiconductor element can be quickly dissipated to maintain the reliability of the semiconductor element. Therefore, the power module substrate is used for consumer equipment and in-vehicle use such as automobiles and electric cars. Such a power module substrate is usually a circuit copper plate pre-patterned on a ceramic substrate that can be arranged in a matrix, or a solid copper plate that has a melting point of copper. It is manufactured by bonding by a direct bonding method in which heat bonding is performed using an active metal or an active metal brazing material bonding method in which heat bonding is performed through an active metal brazing. In the case of an assembly in which a plurality of power module substrates are arranged, the power module substrate is manufactured by finally dividing the power module substrate into divided pieces by dividing grooves. Alternatively, in the power module substrate, a copper plate is directly bonded to each of both main surfaces of the ceramic substrate by heat bonding using an active metal brazing material bonding method or an active metal brazing material bonding method, and then the copper plate is etched to form a circuit copper plate on one main surface. It is produced by forming a solid copper plate on the other main surface.

  In addition, power module substrates on which semiconductor elements that have recently been further increased in power, speed, and integration are mounted quickly dissipate high-temperature and large-scale heat generated from semiconductor elements as quickly as before. It is demanded to make it. However, the conventional power module substrate has a limited heat dissipation due to the relatively thin copper plate. In view of this, it has been attempted to increase the heat dissipation of the power module substrate by increasing the thickness of the circuit copper plate or the copper plate of the solid copper plate.

  In the conventional joined body of ceramic substrate and metal plate, the thickness of the metal plate where the electronic component is mounted is increased in order to prevent warping and cracking of the substrate when soldering the electronic component. Has been proposed (see, for example, Patent Document 1 and Patent Document 2).

JP 59-121890 A JP-A-9-289266

However, the conventional power module substrate and the manufacturing method thereof as described above have the following problems.
(1) The power module substrate that increases the thickness of the copper plate of the circuit copper plate and the solid copper plate as a whole increases the thickness of the copper plate of all parts. Therefore, the ceramic substrate and the copper plate in the reliability evaluation test, particularly the temperature cycle test A large repetitive thermal stress is generated between them and the ceramic substrate is destroyed.
(2) In order to increase the thickness of the required copper plate, when the unnecessary copper plate is half-etched from a thick copper plate as a whole, the thickness of the half-etched portion is reduced. The occurrence of irregularities on the surface causes problems such as non-bonding of bonding wires when electronic components are mounted. In addition, since the copper thickness of the required part remains as it is, a large amount of thermal stress is generated between the ceramic substrate and the copper plate in the reliability evaluation test, particularly in the temperature cycle test, and the ceramic substrate is destroyed. Is supposed to be generated.
(3) In order to increase the thickness of the required copper plate, it is conceivable to make a pattern of a thick copper plate and a thin copper plate separately and heat-bond them independently. Takes time and increases the cost of the power module substrate. In addition, it is difficult to manufacture by the etching method.
(4) When partially increasing the thickness of a copper plate at a necessary portion as disclosed in Japanese Patent Laid-Open No. 59-121890 and Japanese Patent Laid-Open No. 9-289266, a part of the thickened portion is Since it is thicker from the ceramic substrate in a vertical state, a large amount of thermal stress is concentrated between the ceramic substrate and the copper plate in the reliability evaluation test, particularly in the temperature cycle test, in this part, causing the ceramic substrate to break. It is supposed to be.

  The present invention has been made in view of such circumstances, and can increase the thickness of a copper plate at a necessary portion and quickly dissipate heat generated from a semiconductor element without causing damage to the ceramic substrate. It aims at providing the board | substrate for power modules, and its manufacturing method.

  The power module substrate according to the present invention that meets the above-mentioned object is to form a circuit with a plurality of copper plates each having an independent area on one main surface of a ceramic substrate, and to directly mount a semiconductor element in the plurality A circuit copper plate having at least one mounting copper plate, and a power module having one or more solid copper plates joined to the other main surface for dissipating heat from the semiconductor element through the mounting copper plate In the substrate, a first additional laminated copper plate having a smaller outer size than the mounting copper plate is bonded on the mounting copper plate, and a second additional laminated copper plate having a smaller outer size than the solid copper plate on the solid copper plate. Are joined, and between the outer periphery of the first additional stacked copper plate and the mounting copper plate, and between the outer periphery of the second additional stacked copper plate and the solid copper plate, respectively. With the stairs.

  Here, the above power module substrate has copper in the joint corner portion with the mounting copper plate on the outer periphery of the first additional copper layer and the joint corner portion with the solid copper plate on the outer periphery of the second additional copper plate. It is preferable to have a meniscus due to the melt phase.

  In addition, the power module substrate preferably includes a circuit copper plate and dimples or grooves in the outer peripheral portion of the solid copper plate.

  In the power module substrate manufacturing method according to the present invention that meets the above-described object, a plurality of circuits each having an independent region are formed on one main surface of a ceramic substrate, and semiconductor elements are directly mounted in the plurality. A circuit copper plate on which at least one mounting copper plate for mounting is provided, and one or more solid copper plates for dissipating heat from the semiconductor element through the mounting copper plate are joined to the other main surface. In the method of manufacturing a power module substrate, a step of providing a circuit copper plate and a solid copper plate by direct bonding to each of the main surfaces of the ceramic substrate by a direct bonding method or an active metal brazing material bonding method, and an outer shape from the mounting copper plate Preparing a first additional copper sheet having a smaller size and a second additional copper sheet having a smaller outer shape than the solid copper sheet, and a first on the mounting copper sheet After the additional copper plate is brought into contact with the outer periphery so that the outer periphery of the mounting copper plate is exposed, it is heat-bonded by the direct bonding method, and the second additional copper plate is placed on the solid copper plate. After the contact is made so that the outer periphery is exposed, there is a step of heat bonding by a direct bonding method.

  In the power module substrate according to claim 1 or any one of claims 2 and 3 dependent thereon, a first additional laminated copper plate having a smaller outer size than the mount copper plate is bonded onto the mount copper plate. And a second additional copper plate having a smaller outer shape than the solid copper plate is joined on the solid copper plate, and between the outer periphery of the first additional copper plate and the mounting copper plate, and Since there is a step between the outer periphery of the second additional stacked copper plate and the solid copper plate, heat from the semiconductor element can be easily generated through the mounting copper plate provided with the first additional stacked copper plate. Heat can be transferred to the lower side of the substrate, and heat can be dissipated by the solid copper plate provided with the second additional stacked copper plate. In addition, the first additional stacked copper plate and the second additional stacked copper plate have no vertical portions where the outer periphery overlaps at any position due to the steps between the copper plates to which they are joined. The concentration of thermal stress between the substrate and the copper plate can be dispersed, and the ceramic substrate can be prevented from being broken.

  In particular, the power module substrate according to claim 2 includes a joining corner portion with a mounting copper plate on the outer periphery of the first additional overlapping copper plate, and a joining corner portion with the solid copper plate on the outer periphery of the second additional overlapping copper plate. Therefore, it is possible to provide a power module substrate that strengthens the bonding between the mounting copper plate and the first additional laminated copper plate, and the solid copper plate and the second additional laminated copper plate.

  In particular, the power module substrate according to claim 3 has a circuit copper plate and dimples or grooves on the outer peripheral portion of the solid copper plate, so that concentration of thermal stress between the ceramic substrate and the copper plate can be avoided, The destruction of the ceramic substrate can be prevented.

  The method for manufacturing a power module substrate according to claim 4 includes a step of providing a circuit copper plate and a solid copper plate by heat bonding to each of both main surfaces of the ceramic substrate by direct bonding method or active metal brazing material bonding method, A step of preparing a first additional laminated copper plate having a smaller outer size than the mounting copper plate and a second additional laminated copper plate having a smaller outer size than the solid copper plate, and a first additional overlapping copper plate on the mounting copper plate Is attached to the outer periphery so that the outer periphery of the mounting copper plate is exposed, and then heat-bonded by the direct bonding method, and the second additional copper layer is placed on the solid copper plate and the outer periphery of the solid copper is disposed on the outer periphery. Since it has a step of heat bonding by direct bonding method after contacting so as to be exposed, the thickness does not change partially by etching from one copper plate, the thickness variation of the copper plate thickness and the copper plate surface The occurrence of unevenness It can provide a method of manufacturing a substrate for a bonding wire non-bonding occurs without expensive power module. Further, it is possible to provide an inexpensive method for manufacturing a power module substrate that can efficiently dissipate heat generated from a semiconductor element to be mounted, and can prevent breakage due to thermal stress between the ceramic substrate and the copper plate.

Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.
Here, FIGS. 1A to 1C are respectively a top plan view, bottom plan view, AA ′ line longitudinal sectional view, and FIG. 2 (a) of the power module substrate according to one embodiment of the present invention. A)-(D) is explanatory drawing of the manufacturing method of the board | substrate for power modules, respectively.

  The power module substrate according to the embodiment of the present invention includes a case where the power module substrate is manufactured as a single piece on a relatively small ceramic substrate and a case where the power module substrate is formed on a relatively large ceramic substrate. In some cases, a plurality of substrates are arranged as an aggregate.

  As shown in FIGS. 1A to 1C, the power module substrate 10 according to an embodiment of the present invention is a ceramic substrate 11 that has been fired in any of a single piece and an aggregate. A circuit copper plate 12 that forms a circuit with a plurality of copper plates with high thermal conductivity, each of which is independent, is joined to one main surface on the upper surface side. The circuit copper plate 12 is formed to be a pattern of a wiring circuit state, and has at least one mounting copper plate 13 for directly mounting a semiconductor element that generates high heat such as a power transistor. . The circuit copper plate 12 is used to connect the pad electrode of the semiconductor element mounted thereon and the copper plate of another wiring circuit portion with bonding wires or the like, and to reduce the heat generated from the semiconductor element via the mounting copper plate 13. It is provided to transfer heat to the side. In addition, the power module substrate 10 according to the embodiment of the present invention has 1 on the other main surface, which is the lower surface side of the fired ceramic substrate 11, in either case of an individual piece or an assembly. Alternatively, a solid solid copper plate 14 having a plurality of circuits and having no circuit is joined. The solid copper plate 14 is provided to dissipate heat generated from the semiconductor element mounted on the mount copper plate 13 via the mount copper plate 13 and the ceramic substrate 11. Although the thermal expansion coefficient of the power module substrate 10 is greatly different between ceramic and copper, warpage or the like due to the sandwich state in which the circuit copper plate 12 is joined to one main surface of the ceramic substrate 11 and the solid copper plate 14 is joined to the other main surface. Deformation can be prevented.

  In this power module substrate 10, a first additional overlapping copper plate 15 having a smaller outer shape is joined on a mounting copper plate 13 of a circuit copper plate 12 formed on one main surface of a ceramic substrate 11. Have. In addition, the power module substrate 10 has a second additional laminated copper plate 16 having a smaller outer shape joined to a solid copper plate 14 formed on the other main surface of the ceramic substrate 11. Yes. Moreover, the power module substrate 10 has a staircase 17 between the outer periphery of the first additional laminated copper plate 15 and the mounting copper plate 13 so that neither of them is vertical at any position of the outer periphery. ing. In addition, the power module substrate 10 has a staircase 17a between the outer periphery of the second additional stacked copper plate 16 and the solid copper plate 16 so that both are not vertical at any position of the outer periphery. Yes. The power module substrate 10 rapidly dissipates heat from the semiconductor element by increasing the copper plate thickness of the mounted part and the part to dissipate heat, and a ceramic substrate due to repetitive thermal stress such as a temperature cycle test. Can be prevented by providing steps 17 and 17a on the outer periphery of the copper plate at the joint with the ceramic substrate. In addition, the copper plate bonded to one main surface and the other main surface of the ceramic substrate 11 may be bonded separately, or both surfaces can be bonded at once. Moreover, the 1st additional overlap copper plate 15 joined to the mount copper plate 13 and the 2nd additional overlap copper plate 16 joined to the solid copper plate 16 may each be joined separately, and both are joined at once. You can also.

  Normally, a semiconductor element is mounted on the power module substrate 10. However, when the power module substrate 10 is an assembly in which a plurality of individual pieces are arranged, the semiconductor element is mounted. After that, the semiconductor element is mounted on the power module substrate 10 as a single piece after being divided by the dividing grooves provided in the ceramic substrate 11 or after being divided by the dividing grooves. In addition, the dividing groove is a continuous groove formed by laser processing or the like formed in a ceramic green sheet before being fired on a ceramic green sheet before being fired, or after being fired. It is provided as a groove.

  The power module substrate 10 includes a joining corner portion in cross section with the mounting copper plate 13 on the outer periphery of the first additional stacked copper plate 15, and a solid copper plate 16 on the outer periphery of the second additional stacked copper plate 16. It is preferable to have a meniscus 18 made of a molten phase in which copper is melted at a joining corner portion viewed in cross section. By forming the meniscus 18, the power module substrate 10 may be a substrate that firmly bonds the first additional copper plate 15 and the mounting copper plate 13, and the second additional copper plate 16 and the solid copper plate 14, respectively. it can.

  Further, the power module substrate 10 has a circuit copper plate 12 and dimples (not shown) consisting of dents arranged continuously and discontinuously on the outer peripheral portion of the solid copper plate 14 or linearly. It is preferable to have a groove (not shown). The power module substrate 10 can disperse the thermal stress by the dimples or grooves even when repeated thermal stress such as a temperature cycle test is applied, and can prevent the ceramic substrate from being broken. It should be noted that the dimples may be one or a plurality of rows arranged regularly in a straight line, in a staggered manner, or randomly arranged randomly, and the arrangement is limited. However, the shape, size, and depth of the dent are not particularly limited. Moreover, a groove | channel does not specifically limit about a shape, a magnitude | size, and a depth.

Next, with reference to FIGS. 2A to 2D, a method for manufacturing the power module substrate 10 according to the embodiment of the present invention will be described with reference to a large ceramic substrate 11 and a single power module substrate 10. Will be described as a case where a plurality of are arranged as an aggregate.
As shown in FIG. 2 (A), large copper plates 19 and 19a each having a size equivalent to or slightly smaller than that of the ceramic substrate 11 are directly bonded or activated on both main surfaces of the large ceramic substrate 11. Heat-bonded by metal brazing method. The ceramic substrate 11 used here is made of aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), aluminum oxide containing zirconia, etc., and is excellent in insulation, heat resistance, thermal conductivity, substrate strength, etc. It can be used without problems with respect to the high voltage applied to the semiconductor element and the high heat from the semiconductor element. Here, in order to manufacture the ceramic substrate 11 made of Al ₂ O ₃ which is an example of ceramic, a plastic material such as dioctyl phthalate is added to a powder obtained by adding an appropriate amount of a sintering aid such as magnesia, silica and calcia to alumina powder. An agent, a binder such as an acrylic resin, and a solvent such as toluene, xylene, and alcohols are added and kneaded sufficiently, and then defoamed to prepare a slurry having a viscosity of 2000 to 4000 cps. This slurry is formed into a roll sheet having a thickness of, for example, about 0.64 mm by a doctor blade method or the like, cut into an appropriate size to produce a ceramic green sheet, and about 1600 ° C. in the atmosphere. The ceramic substrate 11 is produced by firing.

  In order to produce a ceramic substrate 11 made of AlN, which is an example of ceramic, a sintering aid is added to aluminum nitride powder, and a plasticizer, a binder, and a solvent are added to form a sheet-like ceramic green sheet. Is cut into an appropriate size and fired at a high temperature of about 1700 ° C. in a nitrogen atmosphere.

Furthermore, in order to manufacture the ceramic substrate 11 made of zirconia-containing aluminum oxide, which is an example of ceramic, the main component aluminum oxide is in the range of 70 to 97 wt%, and zirconia (ZrO ₂ ) is added to ₂ to 29.9 wt%. %, Yttria, calcia, magnesia, ceria at least one kind of sintering aid is added in the range of 0.1 to 2 wt%, plasticizer, binder, and solvent are added, for example, , A sheet-like ceramic green sheet having a thickness of 0.25 mm. The ceramic green sheet is cut to an appropriate size and fired at about 1600 ° C. in the atmosphere to produce the ceramic substrate 11. The ceramic substrate 11 made of a fired body containing Al ₂ O ₃ as a main component and the above-mentioned ratio of ZrO ₂ added thereto has a substrate strength while maintaining the same thermal conductivity as the Al ₂ O ₃ single substrate. , can greatly increase the particularly flexural strength (in _Al 2 _{O 3} alone, 3.1 MPa ^{· m 0.5,} the zirconia alumina ceramic, 4.4MPa ^{· m 0.5).} In addition, by adding at least one of yttria, calcia, magnesia, and ceria, the toughness of the ZrO ₂ crystal grains can be improved while suppressing the firing temperature of the substrate to the same level as that of the Al ₂ O ₃ single substrate. Can do. As a result, although the thermal conductivity of the ceramic substrate 11 is lower than that of the AlN substrate, it is possible to compensate for the low thermal conductivity by reducing the thickness, and the ceramic substrate 11 is superior to the Al ₂ O ₃ single substrate. It is possible to have excellent heat dissipation comparable to that of the substrate.

Here, the bonding method using the direct bonding method described above is that the large copper plates 19 and 19a whose surfaces are oxidized in advance are brought into contact with the surface of the ceramic substrate 11 and fired in a nitrogen atmosphere to rise to the vicinity of the melting point of copper. This is a method in which a Cu—O eutectic liquid phase generated by a reaction between copper and a small amount of oxygen is directly bonded to the ceramic substrate 11 as a binder. When the ceramic substrate 11 is made of AlN, it is necessary to form an oxide film on the surface of the ceramic substrate 11, that is, to make the AlN surface Al ₂ O ₃ .

  In addition, the active metal brazing material joining method uses an active metal brazing material in which so-called active metal such as titanium, zirconium, beryllium, etc., which is extremely reactive, is added to an Ag—Cu brazing filler metal or the like. The ceramic substrate 11 and the large copper plates 19 and 19a are joined together. In this method of joining, first, a paste made of an active metal brazing material is applied to each surface of the ceramic substrate 11, and large copper plates 19 and 19 a whose surfaces are previously oxidized are brought into contact with each other, and about 750 to 750 are contacted. In this method, heating is performed at about 850 ° C. and the strength of affinity with oxygen such as titanium is used to directly bond to the ceramic substrate 11. When the ceramic substrate 11 is made of zirconia-based alumina ceramic, the active metal brazing material contains, for example, one or more of zirconium, titanium, hydrogen fluoride, and niobium in Ag-Cu-based brazing. By increasing the affinity for the ceramic substrate 11, it is possible to increase the bonding reaction strength and firmly bond.

  As shown in FIG. 2 (B), a plurality of sets of circuit copper plates 12 are formed on the large copper plates 19 on one main surface side by etching, respectively, on the large copper plates 19 and 19a bonded to the ceramic substrate 11 by heating. A plurality of sets of solid copper plates 14 are formed on the large copper plate 19a on the other main surface side. Here, the formation method of the circuit copper plate 12 and the solid copper plate 14 by the etching method is as follows. First, one of the large copper plates 19 and 19a, for example, the entire surface of the large copper plate 19a on the other main surface side is formed with an etching resist film. Covering. Next, on the large copper plate 19 on one main surface side, a reverse pattern of the circuit copper plate 12 is formed on the photosensitive etching resist film by photolithography, and the portion exposed from the opening of the etching resist film is etched with the etching solution. By processing, a plurality of sets of circuit copper plates 12 are provided. Next, after removing the etching resist films on both sides of the large copper plate 19a on the other main surface side, an etching resist film is formed again on each main surface side in the same manner and exposed from the opening of the etching resist film. The solid copper plate 14 is provided by etching the portion to be etched with an etching solution. In addition, copper sulfate etc. can be used for said etching liquid. The circuit copper plate 12 and the solid copper plate 14 may be formed by etching at one time, or may be formed by etching one side as described above and then etching the other.

2A and 2B, the circuit copper plate 12 and the solid copper plate 14 are formed on the ceramic substrate 11 after the large copper plates 19 and 19a are joined by the direct joining method or the active metal brazing material joining method. Although it has been shown that it is formed by an etching method, it can also be formed by another method. Although not shown, the method will be briefly described.
Before the large copper plates 19 and 19a are bonded to the ceramic substrate 11 by a direct bonding method or an active metal brazing material bonding method, they are punched out by a punching machine, a die press machine or the like, or patterned by an etching method. Is forming. And the copper plate previously formed as the circuit copper plate 12 and the solid copper plate 14 is joined to each main surface of the ceramic substrate 11 by the direct joining method or the active metal brazing material joining method.

  Next, the first additional laminated copper plate 15 for joining on the mounting copper plate 13 which is one of the patterns constituting the circuit copper plate 12 is a punching machine, a die press machine, etc. The shape of the outer shape is smaller than the mounting copper plate 13 by punching or by etching. In the same manner, the second additional laminated copper plate 16 for joining on the solid copper plate 14 is obtained by punching a copper plate of an appropriate size with a punching machine, a die press machine or the like, or by etching using a solid copper plate. 14 having a shape whose outer size is smaller than 14.

  Next, as shown in FIG. 2C, on the mounting copper plate 13, the first additional stacked copper plate 15 is in contact with the outer periphery so that the outer periphery of the mounting copper plate 13 is exposed. And this contact body is heat-joined by the same joining method as the joining method by the said direct joining method. Further, the second additional layered copper plate 16 is brought into contact with the outer periphery of the solid copper plate 14 so that the outer periphery of the solid copper plate 14 is exposed, and is heated and bonded by a direct bonding method. An assembly in which a plurality of module substrates 10 are arranged is produced. In addition, the 1st additional overlap copper plate 15 and the 2nd additional overlap copper plate 16 may be heat-joined simultaneously, and may be heat-joined separately in 2 times, respectively.

  As shown in FIG. 2D, in the case of the large ceramic substrate 11 described above, the dividing grooves 20 for forming the power module substrates 10 from the assembly into the individual pieces are provided with a laser processing machine. Etc. are used to form either one of the main surfaces of the ceramic substrate 11 or both main surfaces. The dividing grooves 20 can be easily formed on the ceramic substrate 11 after firing, but can also be formed on the ceramic green sheet of the ceramic substrate 11 before firing using a pressing blade. Further, in the case of the large-sized ceramic substrate 11, a dummy portion 21 to be removed when divided by the dividing groove 20 is provided on the outer periphery, and a dummy copper plate 22 is provided there.

  The power module substrate of the present invention is mounted with a semiconductor element that generates a large amount of heat through a high voltage, and can be used as a power module substrate for use in, for example, an inverter or an automobile part. . Moreover, the manufacturing method of the power module substrate can be used to produce a highly reliable power module substrate that can flatten the surface of the copper plate and cope with thermal stress.

(A)-(C) are the upper surface side top view, lower surface side top view, and A-A 'line longitudinal cross-sectional view of the board | substrate for power modules which concerns on one embodiment of this invention, respectively. (A)-(D) are explanatory drawings of the manufacturing method of the board | substrate for power modules, respectively.

Explanation of symbols

  10: Power module substrate, 11: Ceramic substrate, 12: Circuit copper plate, 13: Mount copper plate, 14: Solid copper plate, 15: First additional copper plate, 16: Second additional copper plate, 17, 17a: Stairs, 18: Meniscus, 19, 19a: Large copper plate, 20: Dividing groove, 21: Dummy part, 22: Dummy copper plate

Claims (4)

Forming a circuit with a plurality of independent copper plates on one main surface of the ceramic substrate, and having at least one mounting copper plate for directly mounting a semiconductor element in the plurality of copper plates; In the power module substrate having one or a plurality of solid copper plates joined to the other main surface to dissipate heat generated from the semiconductor element through the mount copper plate,
A first additional stacked copper plate having a smaller outer shape than the mount copper plate is joined on the mount copper plate, and a second additional stacked smaller outer shape than the solid copper plate on the solid copper plate. A copper plate is joined, and in addition, between the outer periphery of the first additional stacked copper plate and the mounting copper plate, and between the outer periphery of the second additional stacked copper plate and the solid copper plate, respectively. A power module substrate, comprising steps.   2. The power module substrate according to claim 1, wherein a joint corner portion with the mounting copper plate on the outer periphery of the first additional overlap copper plate and a connection with the solid copper plate on the outer periphery of the second additional overlap copper plate. A power module substrate having a meniscus formed of a molten phase of copper at a corner portion.   3. The power module substrate according to claim 1, wherein the circuit copper plate has dimples or grooves in an outer peripheral portion of the solid copper plate. 4. A circuit copper plate in which a plurality of circuits each having an independent area are formed on one main surface of the ceramic substrate, and at least one mounting copper plate for directly mounting a semiconductor element is provided in the plurality, and the other In the method of manufacturing a power module substrate, wherein one or more solid copper plates for dissipating heat from the semiconductor element through the mount copper plate are joined to the main surface of the power module substrate,
A step of providing the circuit copper plate and the solid copper plate by heat bonding to each of the main surfaces of the ceramic substrate by direct bonding method or active metal brazing material bonding method;
Preparing a first additional stacked copper plate having a smaller outer size than the mounting copper plate, and a second additional stacked copper plate having a smaller outer size than the solid copper plate;
The first additional layered copper plate is brought into contact with the mounting copper plate so that the outer periphery of the mounting copper plate is exposed to the outer periphery, and then heated and bonded by a direct bonding method. A method for manufacturing a power module substrate, comprising: a step of bringing the second additional copper layer into contact with the outer periphery so that the outer periphery of the solid copper is exposed, and then heat-bonding by a direct bonding method.

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