JP2018135251A - Method for manufacturing substrate for power module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a substrate for power modules, capable of achieving high integration of a circuit while maintaining stable productivity.SOLUTION: A method for manufacturing a substrate for power modules includes a bonding step of bonding a ceramics substrate and an aluminum plate by: forming a laminated product by laminating the aluminum plate, used as a circuit layer, on the ceramics substrate via a soldering material; arranging a boron nitride board in piles on the aluminum plate; and heating them in a vacuum atmosphere in a state of pressurizing them in the lamination direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a power module substrate used in a power module or the like that controls a large current and a high voltage.

  As a circuit layer of a power module substrate used for a power module or the like, a circuit layer formed by bonding a metal plate to one surface of a ceramic substrate which is an insulating substrate is known. In addition, as this type of power module substrate, a metal layer having excellent thermal conductivity is bonded to the other surface of the ceramic substrate to form a metal layer, and the heat dissipation plate is bonded via the metal layer. Things are also done. And a power module is manufactured by mounting semiconductor elements, such as a power element, on the upper surface of the circuit layer of the substrate for power modules.

  As described in Patent Documents 1 to 3, as a method of manufacturing a power module substrate configured as described above, a plurality of stacked units each having a metal plate stacked on a ceramic substrate are stacked, and between each stacked unit. By interposing a sheet with cushioning properties, pressurizing and heating in the stacked state, the pressure at the time of pressurization is applied uniformly to the joint surface of the ceramic substrate and the metal plate, and the metal plate is attached to the ceramic substrate. A method of joining is known. As such a sheet, for example, Patent Document 1 describes using a sheet (spacer) in which a heat-resistant material (graphite sheet) is sandwiched between two silicon nitride plates. Patent Document 2 describes using a sheet in which a plurality of carbon (graphite) thin films are stacked and sprayed with BN (boron nitride) or the like as a release agent on the surface thereof. Furthermore, Patent Document 3 describes using a cushion sheet in which a carbon dense layer is formed on both sides of a graphite cushion layer.

Japanese Patent Laid-Open No. 2003-55059 JP 2004-288829 A JP 2008-192823 A

  By the way, with the miniaturization of semiconductor elements, there is an increasing demand for higher integration of circuit layers, that is, to form fine patterns in the circuit layers for power module substrates. However, in a power module substrate having a thick circuit layer, even if a circuit pattern is formed by etching, a pattern with a high aspect ratio cannot be formed, and it is difficult to form a fine pattern. It is also conceivable to form a fine circuit pattern on the metal plate that will be the circuit layer by pressing, but it is difficult to maintain the distance between the circuits when bonding to the ceramic substrate. As in the case of, it is difficult to form a fine pattern.

  Therefore, it is conceivable to form a fine pattern by etching by reducing the thickness of the circuit layer itself. However, when a thin aluminum plate that becomes a circuit layer and a ceramic substrate are joined using a brazing material, if these laminated units are sandwiched between pressure plates such as a carbon plate or a cushion sheet, they diffuse into the aluminum plate. There is a possibility that the brazing component (Si) of the brazing material reaches (diffuses) from the joining surface side of the aluminum plate to the surface, so that the aluminum plate is not only joined to the ceramic substrate but also the aluminum plate and the sheet are joined. . In this case, even if a sheet sprayed with a release agent is used as described in Patent Document 2, it is difficult to reliably release the power module substrate and the pressure plate, and the ceramic substrate breaks. The problem is that productivity is significantly reduced.

  The present invention has been made in view of such circumstances, and an object of the present invention is to manufacture a power module substrate capable of maintaining stable productivity and achieving high integration of circuits.

The method for producing the power module substrate of the present invention comprises:
A laminated body is formed by laminating an aluminum plate to be a circuit layer on a ceramic substrate via a brazing material, and a boron nitride plate is placed on the aluminum plate, and a vacuum is applied in a state where these are pressed in the laminating direction. It has the joining process which joins the said ceramic substrate and the said aluminum plate by heating in atmosphere.

  Boron nitride (BN) is known to be used as a release agent. Even when such a boron nitride release agent is applied to a pressure plate such as a carbon plate, an aluminum plate is used. When the brazing component (Si) of the brazing material diffusing inside reaches the surface from the joining surface side of the aluminum plate, the aluminum plate and the pressure plate may be joined. On the other hand, by arranging a boron nitride plate on an aluminum plate as in the present invention, the circuit layer (power module substrate) can be used even when the brazing component reaches the surface of the circuit layer (aluminum plate). Can be prevented from adhering to and bonding to the boron nitride plate overlaid on the circuit layer. For this reason, the pressure plate, the boron nitride plate, and the power module substrate can be easily disassembled. Therefore, the pressure plate, the boron nitride plate, and the power module substrate (ceramic substrate) are not broken, and the power module substrate can be manufactured stably.

  In addition, since the bonding between the aluminum plate and the pressure plate can be prevented in this way, the substrate for the power module having a thin circuit layer by bonding the thin aluminum plate and the ceramic substrate without reducing the productivity. Can be manufactured. In addition, by configuring such a thin circuit layer, the etching process for forming the circuit pattern can be completed in a short time, so that a fine pattern can be formed in the circuit layer and the circuit can be highly integrated. Can be achieved.

  In the method for manufacturing a power module substrate of the present invention, the boron nitride plate is formed to a thickness of 1.5 mm or more by a hexagonal boron nitride molded body having a boron nitride content of 95% or more. Good.

  By forming a boron nitride plate from a hexagonal boron nitride (hBN) compact, it becomes difficult to generate boron oxide, as will be described later, so the temperature at which the power module substrate is taken out of the heating furnace after the joining process is reduced. Can be higher. Further, by forming the boron nitride plate to a thickness (plate thickness) of 1.5 mm or more, the boron nitride plate itself made of a molded body having a boron nitride content of 95% or more can have sufficient durability. Since it can do, it can avoid that a boron nitride board cracks, when a pressing force is provided to a laminated body in a joining process. On the other hand, if the thickness of the boron nitride plate made of a hexagonal boron nitride molded body is less than 1.5 mm, the bending strength of the boron nitride plate itself is lowered, so that the boron nitride plate may break during pressurization in the joining process. is there. In this case, the boron nitride plate cannot be used repeatedly, which is uneconomical. In this case, the thickness of the boron nitride plate is not limited, but as the thickness increases, it becomes difficult to perform the bonding process by alternately stacking a plurality of laminated bodies and a plurality of boron nitride plates. , Productivity will be reduced.

  In the method for manufacturing a power module substrate according to the present invention, the boron nitride plate may be used by disposing a graphite sheet on the surface opposite to the laminated surface with the aluminum plate.

  By superposing a graphite sheet on a boron nitride plate, the boron nitride plate is brought into contact with the aluminum plate, so that the boron nitride plate and the power module substrate can be easily disassembled after the aluminum plate and the ceramic substrate are joined. . Also, by interposing a graphite sheet having cushioning properties, the entire bonding surface between the aluminum plate and the ceramic substrate can be uniformly pressed, so that the bonding strength between the aluminum plate (circuit layer) and the ceramic substrate can be increased. The bonding reliability of the power module substrate can be improved.

  In the joining step of the method for manufacturing a power module substrate of the present invention, the joined body obtained by joining the ceramic substrate and the aluminum plate is preferably cooled to 400 ° C. or lower and then taken out from the vacuum atmosphere.

Since the boron nitride plate is oxidized at a temperature exceeding 400 ° C. to be boron oxide (B ₂ O ₂ ), the bonded body (power module substrate) obtained by bonding the ceramic substrate and the aluminum plate (circuit layer) has a temperature of 400 ° C. When placed in the atmosphere (oxygen atmosphere) at a temperature higher than that, boron nitride may become boron oxide and adhere to the circuit layer. For this reason, the boron nitride plate and the joined body can be easily disassembled by cooling the joined body to 400 ° C. or lower and placing it in the atmosphere.

  According to the present invention, stable productivity of the power module substrate can be maintained, so that the circuit layer can be thinned and the circuit can be highly integrated.

It is a schematic cross section explaining the manufacturing process of the manufacturing method of the board for power modules of a 1st embodiment of the present invention. It is a flowchart explaining the manufacturing method of the board | substrate for power modules shown in FIG. It is sectional drawing which shows the power module using the board | substrate for power modules manufactured by the manufacturing method of 1st Embodiment. It is sectional drawing explaining the manufacturing method of the board | substrate for power modules of 2nd Embodiment of this invention. It is sectional drawing explaining the manufacturing method of the board | substrate for power modules of 3rd Embodiment of this invention. It is sectional drawing explaining the manufacturing method of the board | substrate for power modules of a comparative example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 3 shows a power module 101 using the power module substrate 10 manufactured by the method for manufacturing a power module substrate according to the first embodiment of the present invention. The power module 101 includes a power module substrate 10, an electronic component 51 such as a semiconductor element mounted on the surface of the power module substrate 10, and a heat sink 52 attached to the back surface of the power module substrate 10. Yes.

  As shown in FIG. 3, the power module substrate 10 includes a ceramic substrate 11, a circuit layer 12 disposed on one surface of the ceramic substrate 11 (upper surface in FIG. 3), and the other surface of the ceramic substrate 11 ( 3, the ceramic substrate 11 and the circuit layer 12, and the ceramic substrate 11 and the metal layer 13 are bonded to each other. Then, the electronic component 51 is mounted (mounted) on the surface (the upper surface in FIG. 3) of the circuit layer 12 of the power module substrate 10, and the power module 101 is manufactured. Further, the power module 101 shown in FIG. 3 is used with the heat sink 52 attached to the surface (the lower surface in FIG. 3) of the metal layer 13.

For the ceramic substrate 11, for example, a nitride ceramic material such as aluminum nitride (AlN) or silicon nitride (Si ₃ N ₄ ), or an oxide ceramic material such as alumina (Al ₂ O ₃ ) can be used. The ceramic substrate 11 has a thickness (plate thickness) of 0.1 mm to 1.0 mm.

  The circuit layer 12 is formed of an aluminum material mainly composed of aluminum (Al), and has a thickness (plate thickness) t1 of 0.005 mm or more and 0.2 mm or less, and is formed relatively thin. The circuit layer 12 is preferably provided with a thickness of 0.1 mm or less. Moreover, the metal layer 13 is not necessarily limited, but is formed of an aluminum material mainly composed of aluminum, and has a thickness (plate thickness) t2 of 0.005 mm to 5.0 mm.

  The heat sink 52 is formed of a metal material whose main component is aluminum (Al) or copper (Cu). Further, the heat sink 52 has a suitable shape such as a flat plate, one in which a large number of pin-shaped fins are integrally formed by hot casting or the like, and one in which strip-like fins are formed in parallel by extrusion. Can be adopted. Further, grease is interposed between the metal layer 13 of the power module substrate 10 and the heat sink 52, and the power module substrate 10 and the heat sink 52 are pressed and fixed by a spring or the like, or the power module substrate 10 is fixed to the heat sink 52. The heat sink 52 is attached to the power module substrate 10 by soldering or brazing to the power module substrate 10.

  Note that a solder material such as Sn—Cu, Sn—Ag—Cu, Zn—Al, or Pb—Sn is used for joining (mounting) the circuit layer 12 and the electronic component 51. Although not shown, the electronic component 51 and the terminal portion of the circuit layer 12 are connected by a wire made of aluminum or the like, ribbon bonding, or the like.

  In the power module substrate 10 configured as described above, an aluminum plate 22 to be the circuit layer 12 is laminated on one surface of the ceramic substrate 11 via a brazing material 31 as shown in FIG. At the same time, an aluminum plate 23 to be the metal layer 13 is laminated on the other surface of the ceramic substrate 11 via a brazing material 32, and these laminated bodies 25 are pressed in the laminating direction as shown in FIG. It heats in the state which carried out, and is manufactured by joining the circuit layer 12 and the metal layer 13 to the ceramic substrate 11, as shown in FIG.1 (c). Hereinafter, a method for manufacturing the power module substrate 10 will be described in detail.

  As shown in FIG. 2, the power module substrate manufacturing method of the present embodiment includes a bonding step S11 and an etching step S12, and is constituted by a plurality of manufacturing steps.

(Joining process)
As shown in FIG. 1A, an aluminum plate 22 to be a circuit layer 12 is laminated on one surface of a ceramic substrate 11 via a brazing material 31, and an aluminum plate 23 to be a metal layer 13 is brazed on the other surface. Lamination is performed via the material 32. As the aluminum plate 22 constituting the circuit layer 12, an aluminum plate made of aluminum or aluminum alloy having a thickness t1 of 0.005 mm or more and 0.2 mm or less can be used, and the brazing material 31 is made of an Al—Si alloy or the like. A brazing material can be used. Moreover, as the aluminum plate 23 which comprises the metal layer 13, the aluminum plate which consists of aluminum or aluminum alloy whose thickness t2 is 0.005 mm or more and 5.0 mm or less can be used, and the brazing | wax material 32 is an Al-Si type alloy. A brazing material such as can be used.

  Next, as shown in FIG. 1B, the laminate 25 of the ceramic substrate 11, the brazing materials 31, 32, and the aluminum plates 22, 23 is disposed between the pair of end spacers 41A. The end spacer 41A has a structure in which the boron nitride plate 42 and the graphite sheet 43 are disposed and integrated, and at least a surface facing each of the aluminum plates 22 and 23 is formed by the boron nitride plate 42. It is.

  The boron nitride plate 42 is formed of a hexagonal boron nitride (hBN) molded body having a boron nitride (BN) content of 95% or more, and has a thickness (plate thickness) of 1.5 mm or more. Hexagonal boron nitride is a ceramic material having excellent heat resistance and lubricity, and can be used up to 900 ° C. in the atmosphere, 1400 ° C. in a vacuum, and up to 2800 ° C. in an inert atmosphere. Further, hexagonal boron nitride is excellent in corrosion resistance against molten metal (aluminum) at high temperatures. As the boron nitride plate 42 constituting the end spacer 41A, for example, show serum made by Showa Denko Co., Ltd. or the like can be used.

Further, the graphite sheet 43, in which scaly graphite thin film is constituted by a plurality of stacked as mica, bulk density is relatively soft in 0.5Mg / ^{m 3} or more 1.3 mg / ^{m 3} or less is there. As the graphite sheet 43 constituting the end spacer 41A, for example, PF-100 manufactured by Toyo Tanso Co., Ltd. can be used.

Then, as shown in FIG. 1B, one end spacer 41 </ b> A is arranged by overlapping the boron nitride plate 42 on the aluminum plate 22 of the laminate 25, and the boron nitride plate 42 is placed on the aluminum plate 23 of the laminate 25. By stacking the other end spacer 41A, the laminated body 25 is placed between the pair of end spacers 41A and heated in a vacuum atmosphere in a state where they are pressurized in the stacking direction. Thus, the ceramic substrate 11 and the aluminum plate 22, and the ceramic substrate 11 and the aluminum plate 23 are brazed and joined (joining step S11). The degree of vacuum in the vacuum atmosphere is preferably 1 × 10 ⁻² Pa or less.

  As a result, the circuit layer 12 is formed on one surface of the ceramic substrate 11 and the metal layer 13 is formed on the other surface of the ceramic substrate 11. As shown in FIG. The power module substrate 10A in which the layer 12, the ceramic substrate 11, and the metal layer 13 are integrally bonded is manufactured. In this case, the applied pressure is, for example, 0.2 MPa to 0.4 MPa, the heating temperature is, for example, 600 ° C. to 640 ° C., and the ceramic substrate 11 and the aluminum plates 22 and 23 are in a vacuum atmosphere in a heating furnace or the like. Are joined together.

  At this time, the aluminum plate 22 to be the circuit layer 12 is provided in a thin thickness of 0.2 mm or less, and the brazing component (Si) of the brazing material 31 is formed at the time of brazing the aluminum plate 22 and the ceramic substrate 11. There is a possibility that the solder component diffuses throughout the aluminum plate 22 and reaches the surface of the circuit layer 12. However, since the boron nitride plate 42 is disposed on the aluminum plate 22, the aluminum plate 22 adheres to the end spacer 41A even when the brazing component reaches the surface of the aluminum plate 22 (circuit layer 12). Can be prevented from being joined together. Therefore, the end spacer 41A and the circuit layer 12 can be easily disassembled, and the power module substrate 10A having the thin circuit layer 12 can be manufactured by joining the thin aluminum plate 22 and the ceramic substrate 11.

The power module substrate 10A (a joined body in the present invention) thus manufactured is taken out from the vacuum atmosphere in the heating furnace after being cooled from the heating temperature at the time of joining to 400 ° C. or lower. The boron nitride plate 42 is oxidized at a temperature exceeding 400 ° C. to become boron oxide (B ₂ O ₂ ). Therefore, when the power module substrate 10A obtained by bonding the ceramic substrate 11 and the aluminum plates 22 and 23 is placed in the atmosphere (oxygen atmosphere) at a temperature exceeding 400 ° C., boron nitride (BN) is converted into boron oxide (B _2). O ₂ ) and may be adhered to the circuit layer 12 or the metal layer 13. Therefore, the edge spacer 41A and the power module substrate 10A can be easily disassembled by placing the power module substrate 10A in the atmosphere after cooling the power module substrate 10A to 400 ° C. or lower.

(Etching process)
Next, a circuit pattern is formed on the circuit layer 12 (and the metal layer 13) by performing an etching process on the circuit layer 12 (and the metal layer 13) bonded to the ceramic substrate 11 (etching step S12). At this time, since the circuit layer 12 is provided with a thickness of 0.2 mm or less, the etching process can be completed in a short time. Therefore, as shown in FIG. 1D, the power module substrate 10 in which the fine pattern is formed on the circuit layer 12 can be manufactured.

  As described above, in the manufacturing method of the present embodiment, when the aluminum plate 22 and the ceramic substrate 11 are joined, the thin aluminum plate 22 and the boron nitride plate 42 are disposed so as to overlap the aluminum plate 22. Even when the brazing component reaches the surface of the aluminum plate 22, it is possible to prevent the end spacer 41A from adhering to and bonding to the aluminum plate 22 (circuit layer 12). Therefore, the end spacer 41A and the power module substrate 10 can be easily disassembled. Therefore, when the end spacer 41A is disassembled, the end spacer 41A and the power module substrate 10 (ceramic substrate 11) are not broken, and the power module substrate 10 can be manufactured stably.

  Further, since the joining of the aluminum plate 22 and the end spacer 41A can be prevented in this way, the thin aluminum plate 22 and the ceramic substrate 11 are joined to reduce the thin circuit layer 12 without reducing the productivity. The power module substrate 10 can be manufactured. Since the thin circuit layer 12 is configured in this way, as described above, the etching process for forming the circuit pattern can be completed in a short time, so that a fine pattern is formed on the circuit layer 12. Therefore, the circuit can be highly integrated.

  Further, since the boron nitride plate 42 is formed of a hexagonal boron nitride molded body as in the first embodiment, boron oxide is less likely to be generated. Therefore, the power module substrate 10A from the heating furnace after the joining step S11. The temperature at the time of taking out can be raised. Further, by forming the boron nitride plate 42 formed of a hexagonal boron nitride molded body having a boron nitride content of 95% or more to a thickness of 1.5 mm or more, the boron nitride plate 42 itself has sufficient durability. Can be made. Therefore, the boron nitride plate 42 can be prevented from cracking when a pressure is applied to the stacked body 25 in the bonding step S11. On the other hand, if the thickness of the boron nitride plate 42 made of a hexagonal boron nitride molded body is less than 1.5 mm, the bending strength of the boron nitride plate 42 itself decreases, so the boron nitride plate 42 during pressurization in the joining step S11. May break. In this case, the boron nitride plate 42 cannot be used repeatedly, which is uneconomical.

  Although there is no limitation on the thickness of the boron nitride plate 42, the thicker the thickness, the thicker the spacer disposed on the aluminum plates 22 and 23. Therefore, as in the second embodiment shown in FIG. 4, when the bonding step S <b> 11 is performed by alternately stacking the plurality of stacked bodies 25 and the plurality of spacers 41 </ b> A and 41 </ b> B, that is, the plurality of stacked bodies. Since it becomes difficult to manufacture a plurality of power module substrates by bonding 25 at a time, productivity is lowered.

  In the second embodiment, the intermediate spacer 41B disposed between the plurality of stacked bodies 25 is configured by integrating and integrating the graphite sheet 43 between the pair of boron nitride plates 42. The boron nitride plate 42 is disposed so as to overlap each of the aluminum plates 22 and 23. Accordingly, when the circuit layer 12 and the metal layer 13 are bonded to the ceramic substrate 11, it is possible to prevent the intermediate spacer 41 </ b> B from being bonded to the circuit layer 12 and the metal layer 13. Therefore, the plurality of power module substrates and the spacers 41A and 41B can be easily disassembled, and a plurality of power module substrates can be manufactured by a single bonding step.

  In the above embodiment, the boron nitride plate 42 is formed of a hexagonal boron nitride molded body. However, in addition to this, a pyrolytic boron nitride (PBN) layer is coated on the surface of the carbon plate. What is formed may be used.

  The pyrolytic boron nitride layer can be coated on the surface of the carbon plate by a CVD (chemical vapor deposition) method or a PVD (physical vapor deposition) method. Thus, by forming the pyrolytic boron nitride layer on the surface of the carbon plate, a boron nitride plate having both the durability (bending strength) of the carbon plate and the releasability by boron nitride can be formed. In this case, since the durability is improved as compared with the case of using a hexagonal boron nitride molded body, it can be used repeatedly, and the productivity of the power module substrate can be improved.

  Furthermore, in the said embodiment, although spacer 41A, 41B which piled up the graphite sheet 43 on the boron nitride board 42 was used, using the graphite sheet 43 is not essential. The joining step may be performed by placing a single boron nitride plate on an aluminum plate (laminate). Also in this case, since the spacer can be prevented from being bonded to the aluminum plate (circuit layer and metal layer) by the boron nitride plate, the power module substrate can be manufactured stably.

  In addition, this invention is not limited to the thing of the said embodiment, In a detailed structure, it is possible to add a various change in the range which does not deviate from the meaning of this invention.

  For example, in the above embodiment, as shown in FIGS. 1D and 3, the method for manufacturing the power module substrate 10 including the ceramic substrate 11, the circuit layer 12, and the metal layer 13 has been described. However, the manufacturing method is not limited to this. For example, as shown in FIG. 5, the present invention can also be applied to a case where an aluminum plate 22 serving as a circuit layer is bonded to only one surface of the ceramic substrate 11. In this case, as shown in FIG. 5, in the joining step, an aluminum plate 22 serving as a circuit layer is laminated on one surface of the ceramic substrate 11 via a brazing material 31, and these laminated bodies 26 are paired with a pair of end portions. It arrange | positions between the spacers 41A. Note that one end spacer 41A overlaid on the aluminum plate 22 has a boron nitride plate 42 and a graphite sheet 43, while the other end spacer 41A overlaid with the ceramic substrate 11 has one end portion. Similarly to the spacer 41A, a laminated plate having a boron nitride plate 42 and a graphite sheet 43 may be used, or a single carbon plate, a laminated plate having a carbon plate and a graphite sheet, or the like may be used.

  Then, the aluminum plate 22 and the boron nitride plate 42 of the one end spacer 41A are arranged so as to overlap each other. Thereby, even when the brazing component reaches the surface of the aluminum plate 22, it is possible to prevent the end spacer 41 </ b> A from adhering to and bonding to the aluminum plate 22. Therefore, the end spacer 41A can be easily disassembled from the power module substrate, and the power module substrate can be manufactured stably.

Examples performed to confirm the effects of the present invention will be described below.
A rectangular plate having a thickness of 0.2 mm and a plane size of 155 mm × 70 mm made of aluminum (4N—Al) having a purity of 99.99% by mass or more was used as the aluminum plate serving as the circuit layer. As the ceramic substrate, a rectangular plate made of aluminum nitride (AlN) having a thickness of 0.635 mm and a planar size of 160 mm × 75 mm was used. In addition, an Al—Si brazing material was used for joining the aluminum plate and the ceramic substrate.

  In Example 1, as shown in FIG. 5, a laminated body 26 in which an aluminum plate 22, a brazing material 31, and a ceramic substrate 11 are laminated in this order is interposed between end spacers 41 </ b> A having a boron nitride plate 42 and a graphite sheet 43. Arranged. In Comparative Example 1, as shown in FIG. 6, a laminate 26 in which an aluminum plate 22, a brazing material 31, and a ceramic substrate 11 are laminated in order is provided with a carbon plate 44 and a graphite sheet 43. It arrange | positioned between the edge part spacers 41C which apply | coated the mold release agent on the surface. Then, the aluminum plate 22 and the ceramic to be a circuit layer are heated by pressing in a laminating direction under a pressure load (pressing force) of 0.3 MPa, a heating temperature of 645 ° C., a heating time of 60 minutes in a vacuum atmosphere. A power module substrate bonded to the substrate 11 was produced.

For the boron nitride plate 42 of the end spacer 41A, a show serum (1.5 mm thickness) made by Showa Denko Co., Ltd. is used, and for the graphite sheet 43, PF-100 (thickness 1. .mu.m) made by Toyo Tanso Co., Ltd. is used. 0 mm) was used. Further, G-347 (thickness 1.0 mm) manufactured by Asahi Graphite Co. is used for the carbon plate 44 of the end spacer 41C, and PF-100 (thickness 1) manufactured by Toyo Tanso Co., Ltd. is used for the graphite sheet 43. 0.0 mm) was used. Moreover, the fine ceramics powder BN UHP-S1 made by Showa Denko Co., Ltd. was used as the mold release agent, and applied to the surface of the carbon plate 44 at an application amount of about 0.16 g / m ^2. Arranged on the plate 22.

  And about the obtained each board | substrate for power modules, the presence or absence of generation | occurrence | production of the crack of a ceramic substrate was confirmed. Table 1 shows the results.

  As can be seen from Table 1, in Comparative Example 1, when the power module substrate sticks to the carbon plate of the end spacer 41C and the end spacer 41C and the power module substrate are peeled off (disassembled), the ceramic substrate 11 Has broken. On the other hand, in Example 1, the edge spacer 41A and the power module substrate could be easily disassembled without causing the ceramic substrate 11 to crack.

10, 10A Power module substrate 11 Ceramic substrate 12 Circuit layer 13 Metal layer 22, 23 Aluminum plate 25, 26 Laminate 31, 32 Brazing material 41A, 41C End spacer (spacer)
41B Intermediate spacer (spacer)
42 Boron nitride plate 43 Graphite sheet 44 Carbon plate 51 Electronic component 52 Heat sink 101 Power module

Claims (4)

  A laminated body is formed by laminating an aluminum plate to be a circuit layer on a ceramic substrate via a brazing material, and a boron nitride plate is placed on the aluminum plate, and a vacuum is applied in a state where these are pressed in the laminating direction. The manufacturing method of the board | substrate for power modules characterized by having the joining process which joins the said ceramic substrate and the said aluminum plate by heating in atmosphere.   2. The power according to claim 1, wherein the boron nitride plate is formed to a thickness of 1.5 mm or more by a hexagonal boron nitride molded body having a boron nitride content of 95% or more. A method for manufacturing a module substrate.   3. The method for manufacturing a power module substrate according to claim 1, wherein the boron nitride plate is used by disposing a graphite sheet on a surface opposite to a laminated surface with the aluminum plate.   In the said joining process, the joined body which joined the said ceramic substrate and the said aluminum plate is taken out from the said vacuum atmosphere, after cooling to 400 degrees C or less. The manufacturing method of the board | substrate for power modules of description.

Images