JP6201827B2 - Manufacturing method of power module substrate with heat sink - Google Patents

Description

  The present invention relates to a method of manufacturing a power module substrate with a heat sink used in a semiconductor device that controls a large current and a high voltage.

  As a power module, there is a power module substrate with a radiator plate in which an aluminum plate is bonded to one surface of a ceramic substrate including aluminum nitride and an aluminum-based radiator plate is bonded to the other surface via an aluminum plate. It is used.

Conventionally, power module substrates with heat sinks have been manufactured as follows.
First, an aluminum plate is laminated on one surface and the other surface of the ceramic substrate via a brazing material suitable for joining the ceramic substrate and the aluminum plate to the surface of the ceramic substrate, and the brazing material is pressed with a predetermined pressure. The power module substrate is manufactured by joining the ceramic substrate and the aluminum plates on both sides by heating and cooling to a temperature equal to or higher than the temperature at which the material melts.

Next, a heat radiating plate is laminated on the aluminum plate on the other surface side of the power module substrate through a brazing material suitable for joining the aluminum plate and the heat radiating plate, and the brazing material is pressed while being pressed at a predetermined pressure. Heat to cool above melting temperature and cool. Thereby, an aluminum plate and a heat sink can be joined and a power module board with a heat sink can be manufactured. And this power module board | substrate with a heat sink is used in the state fastened by the cooler (water cooling etc.).
Moreover, the aluminum plate joined to one surface side of the power module substrate with a heat sink configured as described above is formed as a circuit layer, and electronic components such as power elements are placed on the circuit layer via a solder material. Installed.

However, in the joining of members having different thermal expansion coefficients such as a ceramic substrate and an aluminum plate, warpage occurs due to thermal contraction during cooling after joining.
As a countermeasure against the warp, in Patent Document 1, a circuit board having a warp in which the circuit metal plate becomes a concave surface is manufactured by joining the circuit metal plate and the metal heat sink while bending the ceramic substrate.
In general, when a module is formed using a circuit board, the module is joined to a heat sink so as to be planar and fixed to a fixed component. Therefore, in Patent Document 1, by forming a concave warp on the circuit metal plate side of the circuit board, when the circuit board is fixed flat, compressive stress remains on the circuit board, It is described that the generation and growth of cracks can be reduced during assembly and actual use.

  Moreover, in patent document 2, the curvature which arises at the time of the solder reflow of a ceramic circuit board and a heat sink (heat sink material) is the dominant factors which are the volume ratio and thickness ratio of a metal heat sink and a metal circuit board. It is described that a preferable warp shape can be realized during heating by setting the above structure to an appropriate range.

Japanese Patent Laid-Open No. 10-247763 JP 2006-245437 A

However, what is desired for a power module substrate is to reduce warpage to satisfy the required specifications of the power module. For this reason, as described in Patent Document 1 and Patent Document 2, even when the warpage is controlled as a power module substrate, the warpage must be reduced as a power module to which a heat sink is bonded.
In addition, in a power module substrate with a heat sink, in which the power module substrate and the heat sink are joined, due to the difference in thermal expansion and contraction (warpage) between the power module substrate and the heat sink, these are spread over the entire joint surface. It is difficult to bond them closely, and there is a concern about deterioration of heat dissipation performance. Further, it is desired that the power module substrate with a heat sink is less warped and deformed in the heat treatment process such as soldering of the semiconductor element even after joining to the heat sink.

  The present invention has been made in view of such circumstances, and can reduce the warpage generated when the power module substrate and the heat radiating plate are bonded together, and the entire bonding surface between the power module substrate and the heat radiating plate. It aims at providing the manufacturing method of the board | substrate for power modules with a heat sink which can be joined over.

  In the present invention, a power module substrate in which a circuit layer is disposed on one surface of a ceramic substrate and a metal layer made of aluminum or an aluminum alloy is disposed on the other surface of the ceramic substrate is bonded to a heat sink. A method for manufacturing a power module substrate with a heat sink, wherein a laminate in which the heat sink is placed on the metal layer of the power module substrate is sandwiched between a pair of pressure plates and heated while being pressed in the stacking direction. And a brazing step of brazing the power module substrate and the heat sink, wherein the heat sink is formed by impregnating a silicon carbide porous body with aluminum or an aluminum alloy. The maximum length of the metal layer is 30 mm or more and 200 mm or less and smaller than the maximum length of the heat sink. In the brazing step, the pair of pressure plates includes an upper pressure plate having a convex surface that presses the surface of the circuit layer and a lower pressure plate having a concave surface that presses the back surface of the heat dissipation plate, The curvature radius R1 of the convex surface of the upper pressure plate is 3500 mm or more and 6300 mm or less, and the curvature radius R2 of the concave surface of the lower pressure plate is a state where the convex surface of the upper pressure plate and the concave surface of the lower pressure plate are overlapped. The radius of curvature R1 so that a gap of 0.025 mm or less is provided between the upper pressure plate and the lower pressure plate at positions corresponding to both end positions of the maximum length of the metal layer. It is characterized by being formed larger than.

When using a power module with a heat sink (power module), from the standpoint of maintaining good adhesion between the power module substrate with a heat sink and the cooler, a concave warp (convex to the circuit layer side) with respect to the cooler side. It is more desirable to be a convex warp than a warp.
In the power module substrate with a heat sink of the present invention, the heat sink is formed of an AlSiC-based composite material having a low thermal expansion coefficient, and the heat sink and the power module substrate are laminated at the time of joining the heat sink and the power module substrate. By sandwiching the body between a pair of pressure plates and causing a concave warp with the circuit layer side in the stacking direction on the upper side, by cooling for a predetermined time above the temperature at which the brazing material melts, Even after the brazing material is hardened in a shape along the concave shape and the pressurization state in the stacking direction is released, a joined body that warps in a concave shape with the circuit layer as the upper side, or has a small warpage amount even in the convex shape.

Also, when brazing the power module substrate and the heat sink, due to the difference in thermal expansion and contraction (warping amount) between the power module substrate and the heat sink, they should be bonded together over the entire joint surface. Although it is difficult, the curvature radius R2 of the concave surface of the lower pressure plate is set so that a gap of 0.025 mm or less is provided at the maximum length position of the metal layer with respect to the curvature radius R1 of the convex surface of the upper pressure plate. By forming it larger than the radius R1, it is possible to bond the power module substrate and the heat sink in close contact with each other over the entire bonding surface.
Furthermore, the AlSiC-based composite material that forms the heat sink is a material that combines the low thermal expansion of silicon carbide and the high thermal conductivity of aluminum, so that it can exhibit excellent heat dissipation characteristics while reducing thermal stress. it can.
Therefore, warpage deformation in the heat treatment process can be suppressed, workability can be improved in the process of soldering the element, and substrate reliability due to thermal cycle load can be improved.

  According to the present invention, it is possible to reduce the warpage generated when the power module substrate and the heat radiating plate are joined, and to join the entire surface of the joining surface between the power module substrate and the heat radiating plate. The thermal resistance between the circuit board and the heat radiating plate can be reduced, and the substrate reliability due to the thermal cycle load can be improved.

It is sectional drawing which shows the power module using the board | substrate for power modules with a heat sink. It is sectional drawing explaining the manufacturing method of the board | substrate for power modules with a heat sink which concerns on this invention, (a) is before joining of a board | substrate for power modules and a heat sink, (b) shows the state after joining. It is a side view explaining the jig | tool used for the manufacturing method of the board | substrate for power modules with a heat sink which concerns on this invention. It is a principal part figure explaining the gap between an upper side pressure plate and a lower side pressure plate.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a power module substrate 1 with a heat dissipation plate manufactured by the method for manufacturing a power module substrate with a heat dissipation plate according to the present invention has a heat dissipation bonded to the power module substrate 10 and the power module substrate 10. The power module 100 is manufactured by mounting an electronic component 30 such as a semiconductor chip on the surface of the power module substrate 1 with a heat sink.

  In the manufacturing process of the power module substrate 1 with a heat sink, first, the power module substrate 10 is manufactured as shown in FIG. 2A, and the power module substrate 10 and the heat sink 20 are brazed. A power module substrate 1 with a heat sink as shown in FIG.

  The power module substrate 10 includes a ceramic substrate 11, a circuit layer 12 laminated on one surface of the ceramic substrate 11, and a metal layer 13 laminated on the other surface of the ceramic substrate 11. The electronic component 30 is soldered to the surface of the circuit layer 12 of the power module substrate 10, and the heat sink 20 is attached to the surface of the metal layer 13.

The ceramic substrate 11 is formed in a rectangular shape by nitride ceramics such as AlN (aluminum nitride) and Si ₃ N ₄ (silicon nitride), or oxide ceramics such as Al ₂ O ₃ (alumina). In the form, AlN was used. Further, the thickness of the ceramic substrate 11 is set within a range of 0.2 to 1.5 mm, and in this embodiment is set to 0.635 mm.

  The circuit layer 12 is made of aluminum having a purity of 99% by mass or more. According to JIS standards, aluminum in the 1000s, particularly 1N90 (purity 99.9% by mass or more: so-called 3N aluminum) or 1N99 (purity 99.99% by mass or more: So-called 4N aluminum) can be used. The circuit layer 12 may be made of aluminum alloy, copper, or copper alloy in addition to aluminum.

The metal layer 13 is made of aluminum or an aluminum alloy having a purity of 99% by mass or more, and can be made of aluminum in the 1000s, particularly 1N99 (purity 99.99% by mass or more: so-called 4N aluminum) according to JIS standards.
Further, the maximum length 13L of the metal layer 13 is set to 30 mm or more and 200 mm or less, and is smaller than the maximum length 20L of the heat sink 20 described later. The shape of the metal layer 13 is not limited to a rectangle, but the maximum length 13L in the case of a rectangle is the length of the maximum side of the planar size of the metal layer 13.

  In this embodiment, the circuit layer 12 and the metal layer 13 are aluminum plates made of a rolled plate of aluminum (so-called 4N aluminum) having a purity of 99.99% or more, and the thickness thereof is 0.2 mm to 3.0 mm. The circuit layer 12 has a thickness of 0.6 mm, and the metal layer 13 has a thickness of 2.1 mm.

  The circuit layer 12, the metal layer 13, and the ceramic substrate 11 are joined by, for example, brazing. As the brazing material, an alloy such as Al-Si, Al-Ge, Al-Cu, Al-Mg, or Al-Mn is used.

  The electronic component 30 constituting the power module 100 is formed on a Ni plating (not shown) formed on the surface of the circuit layer 12 with a Sn—Ag—Cu, Zn—Al, Sn—Ag, Sn— Bonding is performed using a solder material such as Cu, Sn—Sb, or Pb—Sn. Reference numeral 31 in FIG. 1 indicates the solder joint layer. The electronic component 30 and the terminal portion of the circuit layer 12 are connected by a bonding wire (not shown) made of aluminum.

  Moreover, the heat sink 20 joined to the power module substrate 10 is formed of an AlSiC-based composite material formed by impregnating a porous body of silicon carbide (SiC) with aluminum or an aluminum alloy. Moreover, the heat sink 20 is formed in a rectangular flat plate shape, and has a thickness of 3 mm to 10 mm and a maximum length 20L of 45 mm to 240 mm. In addition, although the shape of the heat sink 20 is not limited to a rectangle, the maximum length 20L in the case of a rectangle is the length of the maximum side of the planar size of the heat sink 20. Further, as shown in FIG. 2, the power module substrate 10 to which the heat sink 20 is joined is formed smaller than the planar size of the heat sink 20, and the maximum length 13L (the length of the maximum side of the metal layer 13). ) Is smaller than the maximum length 20L of the heat sink 20.

In this embodiment, the heat sink 20 is impregnated with a silicon carbide porous body impregnated with an aluminum alloy containing Si in a range of 5 mass% to 12 mass%, and the surface of the porous body is made of the aluminum alloy. It is made of an AlSiC composite material on which a coating layer is formed. Incidentally, the coefficient of linear expansion of the AlSiC composite material is a ^{8 × 10 -6 / K~12 × 10} -6 / K.
Further, the heat radiating plate 20 includes a plate-shaped heat radiating plate, a plate-shaped heat radiating plate on which fins are formed, and the like.

Next, the manufacturing method of the board | substrate 1 for power modules with a heat sink is demonstrated.
First, as the circuit layer 12 and the metal layer 13, 99.99 mass% or more of pure aluminum rolled sheets are prepared, and these pure aluminum rolled sheets are brazed on one surface and the other surface of the ceramic substrate 11, respectively. The power module substrate 10 in which a pure aluminum rolled plate is bonded to one surface and the other surface of the ceramic substrate 11 is manufactured by laminating the film through the pressure and heating. In this embodiment, brazing is performed using an Al-10% Si brazing material, and the brazing temperature at this time is set to 600 ° C to 655 ° C.

In order to join the heat dissipation plate 20 to the power module substrate 10 configured as described above, first, as shown in FIG. 3, it was configured by a pair of pressure plates 110A and 110B and columns 111 provided at the four corners. Using the jig 112, the heat sink 20 and the power module substrate 10 are stacked and arranged between the pressure plates 110A and 110B.
The pair of pressure plates 110A and 110B of the jig 112 is formed by laminating a carbon plate on the surface of a stainless steel material, and includes an upper pressure plate 110A having a convex surface 110a that presses the surface of the circuit layer 12 of the power module substrate 10. The lower pressure plate 110B having a concave surface 110b that presses the back surface of the heat radiating plate 20, and the opposing surfaces 110a and 110b of the pressure plates 110A and 110B are the joint surfaces of the heat radiating plate 20 and the power module substrate 10. It is formed in the curved surface which makes 20a concave.

  Further, as shown in FIGS. 3 and 4, the pair of pressure plates 110A and 110B has a curvature radius R1 of the convex surface 110a of the upper pressure plate 110A of 3500 mm to 6300 mm, whereas the lower pressure plate When the convex surface 110a of the upper pressure plate 110A and the concave surface 110b of the lower pressure plate 110B are overlapped with each other, the curvature radius R2 of the concave surface 110b of 110B is set at both end positions of the maximum length 13L of the metal layer 13. It is formed larger than the curvature radius R1 so that a gap G of 0.025 mm or less is provided between the upper pressure plate 110A and the lower pressure plate 110B at the corresponding position α.

  And the screw | thread is cut at the both ends of the support | pillar 111, and the nut 113 is fastened so that pressure plate 110A, 110B may be pinched | interposed. Further, an urging means 115 such as a spring for urging the upper pressure plate 110A downward is provided between the top plate 114 supported by the support column 111 and the upper pressure plate 110A. Adjustment is made by tightening the biasing means 115 and the nut 113.

  And in the manufacturing process of the power module substrate 1 with a heat sink of this embodiment, by setting the power module substrate 10 and the heat sink 20 to the jig 112, the power module substrate with a heat sink at the time of manufacturing. 1 can be prevented from projecting to the circuit layer 12 side.

First, the heat radiating plate 20 is placed on the lower pressure plate 110B having the concave surface 110b disposed on the lower side, and the power module substrate 10 is placed thereon with a brazing filler metal foil (not shown) interposed therebetween. The laminated body of the heat sink 20 and the power module substrate 10 is sandwiched between the upper pressure plate 110A having the convex surface 110a. At this time, the laminated body of the heat sink 20 and the power module substrate 10 is pressed in the thickness direction by the concave and convex surfaces 110a and 110b of the pair of pressure plates 110A and 110B, and the joint surface 20a of the heat sink 20 is concavely warped. The deformation is caused to occur. And the heat sink 20 and the metal layer 13 of the power module substrate 10 are fixed by brazing by heating the laminated body of the heat sink 20 and the power module substrate 10 in a pressurized state.
In the present embodiment, the brazing is performed using an Al-10% Si brazing material, in a vacuum atmosphere under the conditions of a load of 0.1 MPa to 3 MPa and a heating temperature of 580 ° C. to 620 ° C. Done.

Next, the joined body of the heat radiating plate 20 and the power module substrate 10 is cooled to room temperature (25 ° C.) in a state where it is attached to the jig 112, that is, in a state where deformation is caused.
In this case, the joined body of the radiator plate 20 and the power module substrate 10 is pressed in the thickness direction by the jig 112 and restrained in a state in which the joint surface 20a of the radiator plate 20 is deformed into a concave warp. Has been. For this reason, the shape of the joined body of the heat sink 20 and the power module substrate 10 due to cooling does not seem to change, but it is pressurized against the stress and can be deformed as a warp during cooling. As a result of being constrained in the absence, plastic deformation occurs.

In the power module substrate 1 with a heat sink manufactured in this way, even after releasing the pressurization state in the stacking direction, as shown in FIG. Or even if it is convex, the amount of warpage is reduced, and the warpage that occurs during manufacturing is reduced.
Further, the curvature radius R2 of the concave surface 110b of the lower pressure plate 110B is set to 0. at a position α corresponding to both end positions of the maximum length 13L of the metal layer 13 with respect to the curvature radius R1 of the convex surface 110a of the upper pressure plate 110A. By applying pressure with a pair of pressure plates 110A and 110B formed to be larger than the curvature radius R1 so that a gap G of 025 mm or less is provided, the power module substrate 10 and the heat radiating plate 20 are brought into close contact with each other over the entire joint surface. Can be joined together.
Furthermore, since the AlSiC-based composite material forming the heat sink 20 is a material that combines the low thermal expansion of silicon carbide and the high thermal conductivity of aluminum, it can exhibit excellent heat dissipation characteristics while reducing thermal stress. Can do.
Therefore, warpage deformation in the heat treatment process can be suppressed, workability in the element soldering process can be improved, and substrate reliability due to thermal cycle load can be improved.

Next, examples and comparative examples performed for confirming the effects of the present invention will be described.
In the manufacturing process of the power module substrate 1 with a heat sink described above, the curvature radius R1 of the convex surface 110a of the upper pressure plate 110A is changed as shown in Table 1, and the power module substrate 10 and the heat sink 20 are joined. A plurality of samples of the power module substrate 1 with the heat sink were manufactured. In Comparative Example 1, Comparative Example 5, and Comparative Example 9, the convex surface 110a of the upper pressure plate 110A was formed as a flat surface.

The power module substrate 10 constituting the power module substrate 1 with each heat sink has the following configuration.
For Examples 1 to 6 and Comparative Examples 1 to 4, a circuit layer made of 4N—Al having a thickness of 30 mm × 25 mm and a thickness of 0.4 mm and a metal layer made of 4N—Al having a thickness of 30 mm × 25 mm and a thickness of 0.4 mm were obtained. A ceramic substrate made of AlN having a thickness of 34 mm × 29 mm and a thickness of 0.635 mm and bonded with an Al—Si brazing material was used.
For Examples 7 to 12 and Comparative Examples 5 to 8, a circuit layer made of 4N—Al having a size of 100 mm × 50 mm and a thickness of 0.4 mm and a metal layer made of 4N—Al having a size of 100 mm × 50 mm and a thickness of 0.4 mm were obtained. A ceramic substrate made of AlN having a size of 104 mm × 54 mm and a thickness of 0.635 mm and bonded with an Al—Si brazing material was used.
For Examples 13 to 18 and Comparative Examples 9 to 12, a circuit layer made of 4N-Al having a thickness of 200 mm × 65 mm and a thickness of 0.4 mm and a metal layer made of 4N—Al having a thickness of 200 mm × 65 mm and a thickness of 0.4 mm were obtained. A ceramic substrate made of AlN having a thickness of 204 mm × 69 mm and a thickness of 0.635 mm, joined with an Al—Si brazing material was used.

  The heat sink 20 is impregnated with a silicon carbide porous body impregnated with an aluminum alloy containing Si in a range of 5 mass% to 12 mass%, and a coating layer of the aluminum alloy is formed on the surface of the porous body. The formed AlSiC composite material was used. As Examples 1 to 6 and Comparative Examples 1 to 4, a rectangular plate having a size of 45 mm × 35 mm and a thickness of 5 mm was used as the heat sink 20. Further, for Examples 7 to 12 and Comparative Examples 5 to 8, a rectangular plate of 140 mm × 60 mm and a thickness of 5 mm was used, and for Examples 13 to 18 and Comparative Examples 9 to 12 a rectangular plate of 240 mm × 75 mm and a thickness of 5 mm was used. .

And about the sample of these power module board | substrates 1 with a heat sink, the joining rate of the power module board | substrate 10 (metal layer 13) and the heat sink 20, and the curvature which arose in the sample of these power module board | substrates 1 with a heat sink The amount Z was evaluated respectively.
The evaluation of the bonding rate is an evaluation of the bonding surface between the metal layer 13 and the heat sink 20 using an ultrasonic deep wound device, and the bonding rate = (bonding area−peeling area) / bonding area × 100 (%). Calculated from the formula. In addition, in the ultrasonic deep wound image which image | photographed the joining surface of the metal layer 13 and the heat sink 20, since the peeling part is shown by a white part, the peeling area was calculated | required by measuring the area of a white part. Further, the bonding area was the area of the bonding surface of the metal layer 13 that is the area to be bonded before bonding. Then, a bonding rate of less than 90% was evaluated as defective “x”, a bonding rate of 90% to less than 95% was evaluated as “good”, and a bonding rate of 95% or more was evaluated as optimal “◎”.

  The warpage amount Z was measured as a warpage amount Z by measuring the change in flatness of the back surface of the heat sink 20 using a moire type three-dimensional shape measuring machine at room temperature of 25 ° C. The warpage amount Z was defined as a positive warpage amount (+) when warped convexly toward the circuit layer side, and a negative warpage amount (−) when warped concavely toward the circuit layer side. That is, the case of warping as shown in FIG. Tables 1 to 3 show the evaluation results of the joining ratio and the measurement results of the warpage amount. Table 1 shows the case where the maximum length L13 of the metal layer is 30 mm, Table 2 shows the case where the maximum length L13 of the metal layer is 100 mm, and Table 3 shows the case where the maximum length L13 of the metal layer is 200 mm. It is a result.

  As can be seen from Tables 1 to 3, by applying pressure with a pair of pressure plates 110A and 110B in which the gap G at the position α is 0.025 mm or less, the joining ratio between the power module substrate 10 and the heat radiating plate 20 is increased. It was possible to be 90% or more, and it was possible to bond with almost the entire bonding surface in close contact. Further, by forming the curvature radius R1 of the convex surface 110a of the upper pressure plate 110A as 3500 mm or more and 6300 mm or less, the heat radiation in the heat sink power module substrate of the same size as compared with the case where the upper pressure plate 110A is formed as a flat surface. The warp amount Z of the plate could be reduced in all cases.

In addition, this invention is not limited to the thing of the structure 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, a method of joining using an active metal brazing material may be employed for brazing a copper circuit layer and a ceramic substrate. For example, an active metal brazing material containing active metal Ti (for example, Ag-27.4 mass% Cu-2.0 mass% Ti, etc.) is used to pressurize a laminate of a copper circuit layer and a ceramic substrate. In this state, the circuit layer and the ceramic substrate can be joined via the Ag-Cu alloy by preferentially diffusing Ti, which is an active metal, into the ceramic substrate.

DESCRIPTION OF SYMBOLS 1 Power module board | substrate with a heat sink 10 Power module board | substrate 11 Ceramic substrate 12 Circuit layer 13 Metal layer 20 Heat sink 20a Joint surface 30 Electronic component 31 Solder joint layer 110A Upper pressure plate 110B Lower pressure plate 111 Post 112 Jig 113 Nut 114 Top plate 115 Energizing means

Claims (1)

A power module with a heat dissipation plate for joining a power module substrate having a circuit layer disposed on one surface of a ceramic substrate and a metal layer made of aluminum or an aluminum alloy disposed on the other surface of the ceramic substrate. A method of manufacturing a module substrate,
The power module substrate and the heat dissipation plate are heated by pressing a laminate in which the heat dissipation plate is placed on the metal layer of the power module substrate between a pair of pressure plates while being pressed in the stacking direction. A brazing process for brazing,
The heat sink is formed of an AlSiC-based composite material formed by impregnating a porous body of silicon carbide with aluminum or an aluminum alloy, and the maximum length of the metal layer is 30 mm or more and 200 mm or less than the maximum length of the heat sink. Is also formed small,
In the brazing step, the pair of pressure plates includes an upper pressure plate having a convex surface that presses the surface of the circuit layer and a lower pressure plate having a concave surface that presses the back surface of the heat sink.
The curvature radius R1 of the convex surface of the upper pressure plate is 3500 mm or more and 6300 mm or less, and the curvature radius R2 of the concave surface of the lower pressure plate is obtained by superimposing the convex surface of the upper pressure plate and the concave surface of the lower pressure plate. The curvature radius is set so that a gap of 0.025 mm or less is provided between the upper pressure plate and the lower pressure plate at positions corresponding to both end positions of the maximum length of the metal layer in the state. A method for manufacturing a power module substrate with a heat sink, wherein the substrate is formed larger than R1.

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