JP2016181549A - Power module board with heat sink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power module board with a heat sink having high joint reliability that can reduce not only initial warp after joint to the heat sink, but also warp of a ceramic board under a use environment.SOLUTION: A power module board 10A with a heat sink is configured so that a circuit layer 12 is joined to one surface of a ceramic substrate 11, and the heat sink is joined to the other surface of the ceramic substrate 11 via a heat radiating layer 13. A housing concave portion 31 in which at least a part of the heat radiation layer 13 is housed is formed on a top plate portion 30A of the heat sink, a concave groove portion 33A is formed along the peripheral edge portion 13a of the surface of the heat radiation layer 13 is formed on the bottom surface of the housing concave portion 31, the peripheral edge portion 13a of the surface of the heat radiation layer 13 is provided so as to protrude halfway in the direction of the width W of the concave groove portion 33A, and the inner portion excluding the peripheral edge portion 13a is joined to the surface of a pedestal portion 34A surrounded by the recessed groove portion 33A of the bottom surface of the housing recess portion 31.SELECTED DRAWING: Figure 1

Description

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

  In general, a power module is bonded to a metal plate that forms a circuit layer on one surface of a ceramic substrate such as aluminum nitride, and a heat radiating plate (via a metal plate that forms a heat radiating layer on the other surface). A power module substrate with a heat sink to which a heat sink is bonded is used, and a semiconductor chip such as a power element is mounted on a circuit layer of the power module substrate with a heat sink via a solder material to manufacture a power module.

  For example, in Patent Document 1, an accommodation recess in which at least a part of the heat dissipation layer (metal layer) is accommodated is formed in the top plate portion of the heat sink, and the surface of the heat dissipation layer and the bottom surface of the accommodation recess are joined. There has been proposed a power module substrate with a heat sink in which a heat dissipation layer is made of a metal having a deformation resistance smaller than that of the top plate. In the power module substrate with a heat sink described in Patent Document 1, since the surface of the heat dissipation layer and the bottom surface of the housing recess are joined, the heat dissipation layer disposed on the other side of the insulating substrate and the top plate of the heat sink It is described that the thickness of the film can be reduced and the thermal stress due to the thermal cycle can be reduced. Further, since the heat dissipation layer located between the insulating substrate and the top plate portion of the heat sink is made of a metal having a lower deformation resistance than the top plate portion, the heat sink top plate portion and the heat dissipation layer are joined 2. It is described that the deformation of the top plate portion can be suppressed by deformation of the heat dissipation layer having a small deformation resistance when thermal stress is applied in the next bonding. Further, it is described that the rigidity of the heat sink itself can be ensured because the top plate portion is made of a metal having a large deformation resistance.

JP 2008-277654 A

  However, as in the case of the power module substrate with a heat sink described in Patent Document 1, when the housing recess is formed in the top plate portion of the heat sink, the heat sink directly below the heat dissipation layer, that is, directly below the ceramic substrate is formed thin. However, since the peripheral edge on the outer peripheral side is thicker than the housing recess, deformation resistance increases due to the rigidity of the peripheral edge, and a load is applied to the ceramic substrate during use, which may cause cracks in the ceramic substrate. There is.

  The present invention has been made in view of such circumstances, and can reduce the load applied to the ceramic substrate even in use, and the ceramic substrate is not cracked. An object is to provide a substrate.

The substrate for a power module with a heat sink of the present invention,
A circuit layer is bonded to one surface of the ceramic substrate, and a heat sink is bonded to the other surface of the ceramic substrate via a heat dissipation layer,
The top plate portion of the heat sink is formed with an accommodation recess for accommodating at least a part of the heat dissipation layer,
On the bottom surface of the housing recess, a recessed groove is formed along the peripheral edge of the surface of the heat dissipation layer,
The peripheral edge of the surface of the heat dissipation layer is provided so as to protrude to a middle position of the width of the concave groove, and the inner portion excluding the peripheral edge and the surface of the pedestal surrounded by the concave groove on the bottom surface of the housing recess, Are joined.

Since the concave groove portion is formed on the bottom surface of the housing concave portion, it is possible to reduce the influence of the inner pedestal portion due to the highly rigid portion (periphery portion of the top plate portion) on the outer peripheral side of the concave groove portion during heating or the like. it can. Thereby, since the deformation resistance of the pedestal portion during heating or the like can be reduced, the thermal stress applied to the ceramic substrate can be reduced, and the ceramic substrate can be prevented from being cracked. Further, the thermal stress applied to the ceramic substrate can be reliably reduced by projecting the peripheral portion of the heat dissipation layer to the middle position of the width of the concave groove portion and joining the inner portion excluding the projected peripheral portion to the pedestal portion. Can do.
Therefore, not only the initial warping after joining the power module substrate and the heat sink, but also the warpage of the ceramic substrate can be reduced in the usage environment, and the joining reliability of the power module substrate with the heat sink can be improved.

In the power module substrate with a heat sink of the present invention,
The circuit layer and the heat dissipation layer are formed of the same material and have the same planar size.

  Since the circuit layer and the heat dissipation layer have a symmetric structure with the ceramic substrate as the center, stress acting on both surfaces of the ceramic substrate during heating or the like is less likely to occur and warpage is less likely to occur. Accordingly, the thermal stress applied to the ceramic substrate during heating or the like can be further reduced, and not only the initial warping after joining the power module substrate and the heat sink but also the warping of the ceramic substrate can be reduced in the use environment. It is possible to improve the bonding reliability of the power module substrate with a heat sink.

In the power module substrate with a heat sink of the present invention,
The circuit layer includes a first metal layer bonded to the ceramic substrate and a second metal layer formed in a plane size smaller than the first metal layer and bonded to a central portion of the surface opposite to the ceramic substrate. The heat dissipation layer is formed in the same plane size with the same material as the first metal layer,
The top plate portion is formed of the same material as the second metal layer, and the surface of the pedestal portion is formed in the same plane size as the second metal layer.

  Since the circuit layer is a laminated structure of the first metal layer and the second metal layer, a symmetrical structure is formed around the ceramic substrate by the heat dissipation layer, the first metal layer, the top plate portion of the heat sink and the second metal layer, The stress acting on both surfaces of the ceramic substrate during heating or the like is less likely to be biased, and warpage is less likely to occur. Therefore, it is possible to reduce the thermal stress applied to the ceramic substrate at the time of heating, etc., to prevent the occurrence of cracks, and not only in the initial warping after joining the power module substrate and the heat sink, but also in the usage environment The warpage of the ceramic substrate can be reduced, and the bonding reliability of the power module substrate with a heat sink can be increased.

  ADVANTAGE OF THE INVENTION According to this invention, the thermal stress concerning a ceramic substrate can be reduced also in a use environment, and the board | substrate for power modules with a heat sink which does not produce a crack in a ceramic substrate can be provided. Furthermore, since the symmetrical structure is formed around the ceramic substrate, not only the initial warpage after joining to the heat sink but also the warpage of the ceramic substrate can be reduced in the usage environment. Bonding reliability can be improved.

It is sectional drawing which shows 1st Embodiment of the board | substrate for power modules with a heat sink of this invention. It is sectional drawing of the power module using the board | substrate for power modules with a heat sink shown in FIG. It is sectional drawing which shows the manufacturing method of the board | substrate for power modules with a heat sink shown in FIG. 1 for every process. It is sectional drawing which shows the board | substrate for power modules with a heat sink of 2nd Embodiment of this invention. It is a figure explaining the analysis model of the board | substrate for power modules with a heat sink, (a) is an Example, (b) shows a comparative example, (c) shows a prior art example. It is a figure explaining the analysis model of the board | substrate for power modules with a heat sink, (a) shows an Example, (c) shows a prior art example. It is a front view of the pressurization apparatus used for manufacture of the substrate for power modules with a heat sink.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a power module substrate 10A with a heat sink according to a first embodiment of the present invention. FIG. 2 shows a power module 100 using the power module substrate 10A with a heat sink according to the first embodiment of the present invention. The power module 100 includes a power module substrate 10A with a heat sink, a semiconductor element 60 bonded to the power module substrate 10A with a heat sink, and a lead frame 70 for external connection. The substrate 10 </ b> A is sealed with a resin mold 40.

  As shown in FIG. 1, the power module substrate 10A with a heat sink is obtained by bonding the power module substrate 15 to the top plate portion 30A of the heat sink. The power module substrate 15 includes a ceramic substrate 11, a circuit layer 12 bonded to one surface of the ceramic substrate 11 by brazing, and a heat dissipation layer 13 bonded to the other surface of the ceramic substrate 11 by brazing. With.

For the ceramic substrate 11, for example, nitride ceramics such as AlN (aluminum nitride) and Si ₃ N ₄ (silicon nitride), or oxide ceramics such as Al ₂ O ₃ (alumina) can be used. Moreover, the thickness of the ceramic substrate 11 can be set within a range of 0.2 mm to 1.5 mm. In the present embodiment, the ceramic substrate 11 is made of Si ₃ N ₄ and has a thickness of 0.32 mm.

  The circuit layer 12 is made of, for example, pure aluminum or an aluminum alloy, and is formed by bonding a plate material whose thickness is set within a range of 0.1 mm to 3.0 mm to the ceramic substrate 11. In the present embodiment, the circuit layer 12 is formed by an aluminum plate having a purity of 99.99% by mass or more and a JIS standard of 1N99 (purity 99,99% by mass or more: so-called 4N aluminum) having a thickness of 0.6 mm. It is brazed to the substrate 11.

  The heat dissipation layer 13 is formed of the same material as the circuit layer 12 and has the same planar size and thickness as the circuit layer 12 (substantially the same meaning). In the present embodiment, the heat dissipation layer 13 is formed by brazing an aluminum plate having the same purity as the circuit layer 12 and having a thickness of 0.6 mm or more to a thickness of 0.6 mm to the ceramic substrate 11.

  The heat sink bonded to the power module substrate 15 is formed of a plate material made of an aluminum alloy such as A3003. And the accommodation recessed part 31 in which at least one part of the thermal radiation layer 13 is accommodated is formed in the top-plate part 30A of the heat sink joined to the thermal radiation layer 13, and a thick part is left on the outer peripheral side of the accommodation concave part 31. A flange portion 32 is formed. Further, a concave groove portion 33A is formed along the peripheral edge portion 13a of the surface of the heat radiation layer 13 on the bottom surface of the housing concave portion 31, and a pedestal portion 34A surrounded by the concave groove portion 33A is formed on the bottom surface of the housing concave portion 31. . Then, the power module substrate 15 and the top plate portion 30A of the heat sink are joined together by brazing the surface of the pedestal portion 34A and the inner portion excluding the peripheral edge portion 13a of the surface of the heat dissipation layer 13. .

  Further, as shown in FIG. 1, the recessed groove portion 33 </ b> A is formed with a certain width W immediately below the peripheral edge portion 13 a of the heat radiating layer 13, and extends inside the peripheral edge portion 13 a of the heat radiating layer 13. It is formed with a width W so as to be formed outside the peripheral edge portion 13 a, that is, across the peripheral edge portion 13 a of the heat radiation layer 13. As a result, the peripheral edge portion 13a of the heat radiation layer 13 is disposed so as to protrude to the middle position of the width W of the concave groove portion 33A, and the inner portion excluding the peripheral edge portion 13a and the surface of the pedestal portion 34A are joined.

  As described above, the top plate portion 30A is formed such that the thickness (thickness t1) of the bottom surface portion of the housing recess 31 is thinner than the flange portion 32, and further, the recess groove portion 33A is provided on the bottom surface of the housing recess 31 to further increase the plate thickness. A portion (thickness t2) in which is made thinner is provided. In the present embodiment, the top plate portion 30A is formed of a plate material having a total thickness of 4.0 mm made of an A3003 aluminum alloy, the flange portion 32 has a thickness t0 of 4.0 mm, and the bottom t1 of the housing recess 31 has a thickness of t1. The thickness t2 of the recessed groove portion 33A is 2 mm and 0.6 mm.

  Then, as shown in FIG. 2, a semiconductor element 60 is soldered to the surface of the circuit layer 12 of the power module substrate 15 constituting the power module substrate 10A with a heat sink, and the semiconductor element 60 and the circuit layer 12 are externally connected. A connecting lead frame 70 is connected. The semiconductor element 60 and the power module substrate 10A with a heat sink are integrated by being sealed with resin, and the external connection lead frame 70 partially protrudes to the outside of the resin mold 40. Is provided.

The semiconductor element 60 is an electronic component including a semiconductor, and an IGBT (Insulated Gate Bipolar Transistor), a MOSFET (Metal Oxide Field Transistor Transistor), a FWD (FelDW, etc.), depending on the function required. Various semiconductor elements are selected. The solder material for joining the semiconductor element 60 is, for example, a Sn—Sb, Sn—Ag, Sn—Cu, Sn—In, or Sn—Ag—Cu solder material (so-called lead-free solder material). It is said.
The external connection lead frame 70 is formed of, for example, copper or a copper alloy, and is connected by ultrasonic bonding or soldering.
As the mold resin 40, for example, an epoxy resin containing a SiO ₂ filler can be used, and the mold resin 40 is formed by, for example, transfer molding.

Next, an example of a method for manufacturing the power module substrate with heat sink 10A configured as described above will be described.
First, as shown in FIGS. 3A and 3B, the circuit layer 12 is laminated on one surface of the ceramic substrate 11, the heat radiation layer 13 is laminated on the other surface, and these are integrally joined. For these joining, a brazing material (not shown) made of an alloy such as Al—Si is used. For example, the ceramic substrate 11, the circuit layer 12, and the heat dissipation layer 13 are laminated via a brazing material foil 25. Let the laminated body be the state pressurized by the lamination direction using the pressurization apparatus 110 shown in FIG.

The pressure device 110 shown in FIG. 7 includes a base plate 111, guide posts 112 that are vertically attached to the four corners of the upper surface of the base plate 111, a fixed plate 113 that is fixed to the upper ends of the guide posts 112, Between the base plate 111 and the fixed plate 113, a pressing plate 114 supported by the guide post 112 so as to be movable up and down, and provided between the fixed plate 113 and the pressing plate 114, the pressing plate 114 is urged downward. And an urging means 115 such as a spring.
The fixed plate 113 and the pressing plate 114 are arranged in parallel to the base plate 111, and the above-described laminate S is arranged between the base plate 111 and the pressing plate 114. Carbon sheets 116 are disposed on both sides of the laminate S to make the pressure uniform.
In a state where the pressure is applied by the pressure device 110, the pressure device 110 and the pressure device 110 are installed in a heating furnace (not shown) and brazed by heating to a brazing temperature in a vacuum atmosphere. In this case, the applied pressure is, for example, 0.68 MPa (7 kgf / cm ² ), and the heating temperature is, for example, 640 ° C.

  Then, as shown in FIG. 3B, the top plate portion 30A of the heat sink is joined to the power module substrate 15 to which the ceramic substrate 11, the circuit layer 12, and the heat dissipation layer 13 are joined. First, the heat sink top plate 30 </ b> A is laminated on the heat dissipation layer 13 of the power module substrate 15 via the brazing material 26. Then, these laminated bodies are heated in a vacuum atmosphere or an inert atmosphere together with the pressurizing device 110 in a state where the pressurizing device 110 similar to that in FIG. The top plate portion 30A of the heat sink is brazed. As the brazing material 26 in this case, for example, a double-sided brazing clad material in which an Al—Si—Mg based brazing material layer is formed on both surfaces of a core material made of an A3003 series aluminum alloy may be used. The heat radiation layer 13 of the power module substrate 15 and the top plate portion 30A of the heat sink are joined together by a fluxless brazing method using In this case, for example, pressurizing to 0.001 MPa or more and 0.5 MPa or less, and heating at a joining temperature of 559 ° C. or more and 625 ° C. or less in an inert atmosphere such as nitrogen, the heat dissipation layer 13 and the top plate portion 30A are joined. Thus, a power module substrate 10A with a heat sink is obtained.

  Then, the semiconductor element 60 is soldered (die-bonded) to the circuit layer 12 of the power module substrate 10A with a heat sink manufactured as described above. Further, after the external connection lead frame 70 is connected to the semiconductor element 60 and the circuit layer 12 by a method such as ultrasonic bonding or soldering, the semiconductor element 60 and the power module substrate 10A with a heat sink are connected to the resin mold 40. Resin sealing is performed by transfer molding.

  In the power module substrate with heat sink 10A of the first embodiment manufactured as described above, the housing recess 31 is provided in the top plate portion 30A of the heat sink, and the groove 33A is formed in the bottom surface of the housing recess 31. During heating, the influence of the inner pedestal portion 34A can be reduced by the highly rigid flange portion 32 on the outer peripheral side of the concave groove portion 33A. Thereby, since the deformation resistance of the pedestal portion 34A at the time of heating or the like can be reduced, the thermal stress applied to the ceramic substrate 11 can be reduced, and the ceramic substrate 11 can be prevented from being cracked. Further, the peripheral edge portion 13a of the heat radiation layer 13 is protruded to the middle position of the width W of the concave groove portion 33A, and the inner portion excluding the protruded peripheral edge portion 13a is joined to the pedestal portion 34A of the top plate portion 30A. In addition, the thermal stress applied to the ceramic substrate 11 can be reduced.

FIG. 4 shows a power module substrate 20A with a heat sink according to a second embodiment of the present invention.
In the power module substrate 20A with a heat sink of the second embodiment shown in FIG. 4, the circuit layer 12 is bonded to the ceramic substrate 11 and the second metal layer 17 is bonded to the first metal layer 17. A laminated structure having the metal layer 18 is formed. The second metal layer 18 is formed to have a smaller planar size than the first metal layer 17 and is bonded to the center of the surface of the first metal layer 17 opposite to the ceramic substrate 11.

The heat dissipation layer 13 is formed in the same plane size with the same material as the first metal layer 17 of the circuit layer 12. The top plate portion 30 </ b> A of the heat sink is formed of the same material as the second metal layer 18, and the surface of the pedestal portion 34 </ b> A is formed in the same planar size as the surface of the second metal layer 18.
The thickness of the first metal layer 17 of the circuit layer 12 and the thickness of the heat dissipation layer 13 are set to the same thickness, and the thickness of the second metal layer 18 of the circuit layer 12 and the pedestal portion 34A of the top plate portion 30A. The thickness is set to the same thickness, and a symmetrical structure with the ceramic substrate 11 as the center is formed.

Specifically, the ceramic substrate 11 is made of Si ₃ N ₄ and has a thickness of 0.32 mm. The first metal layer 17 and the heat dissipation layer 13 constituting the circuit layer 12 both have a purity of 99.99% by mass or more, and the JIS standard has a thickness of 1N99 (purity 99,99% by mass or more: so-called 4N aluminum). A 6 mm aluminum plate is formed and brazed to the ceramic substrate 11. The second metal layer 18 is formed of a plate material having a thickness of 1.2 mm made of an A3003 aluminum alloy. The top plate portion 30A of the heat sink is formed of a plate material having a total thickness of 4.0 mm made of an A3003 series aluminum alloy, the flange portion 32 has a thickness t0 of 4.0 mm, and the bottom surface thickness t1 of the housing recess 31 has a thickness of 1.2 mm. The thickness t2 of the concave groove portion 33A is formed to be 0.6 mm. In the power module substrate 20A with a heat sink shown in FIG. 4, the surface of the flange portion 32 and the surface of the circuit layer 12 are arranged at substantially the same height.

  Thus, in the power module substrate with heat sink 20A of the second embodiment, the circuit layer 12 has a laminated structure of the first metal layer 17 and the second metal layer 18, and the heat dissipation layer 13, the first metal layer 17, and Since the top plate portion 30A of the heat sink and the second metal layer 18 form a symmetrical structure with the ceramic substrate 11 as the center, stress acting on both sides of the ceramic substrate 11 during heating or the like is less likely to be biased, and warping, etc. Deformation can be made difficult to occur. Therefore, not only the initial warpage at the time of laminating each layer, but also the occurrence of warpage can be suppressed during the mounting process of the semiconductor element and in the usage environment, and good heat dissipation can be exhibited.

In the second embodiment, the combination of the metal plates used for the circuit layer 12 is such that the first metal layer 17 is aluminum (so-called 4N aluminum) having a purity of 99.99% by mass or more, and the second metal layer 18 is A3003 series. The heat dissipation layer 13 and the top plate portion 30A of the heat sink are used for the first metal layer 17 and the second metal so that the first metal layer 17 and the second metal layer 18 are symmetrical. Although the layer 18 is formed of the same material, the configuration of the present invention is not limited to this combination. For example, the first metal layer 17 and the heat dissipation layer 13 are made of aluminum having a purity of 99.99% by mass or more, and the second metal layer 18 and the top plate portion 30A of the heat sink are made of other aluminum alloys such as A6063 series, , Copper having a purity of 99.96% by mass or more (oxygen-free copper), copper having a purity of 99.90% by mass or more (tough pitch copper), ZC alloy manufactured by Mitsubishi Shindoh Co., Ltd. (Cu 99.98% by mass-Zr0.02 mass) %) Etc., and these may be combined.
When the second metal layer 18 and the top plate portion 30A of the heat sink are formed of copper or copper alloy, the first metal layer 17, the second metal layer 18, the heat radiation layer 13, and the top plate portion 30A of the heat sink. Can be bonded by solid phase diffusion bonding.

In any of the above combinations, as shown in the first and second embodiments, the housing recess 31 is formed in the top plate portion 30A of the heat sink, and the groove 33A is formed on the bottom surface of the housing recess 31. By forming the above, it is possible to reduce the influence of the inner pedestal portion 34A due to the highly rigid flange portion 32 on the outer peripheral side of the concave groove portion 33A during heating or the like. For this reason, the deformation resistance of the pedestal portion 34A during heating or the like can be reduced, the thermal stress applied to the ceramic substrate 11 can be reduced, and the ceramic substrate 11 can be prevented from cracking. Further, the peripheral edge portion 13a of the heat radiation layer 13 is projected to a middle position of the width W of the concave groove portion 33A, and the inner portion excluding the projected peripheral edge portion 13a is joined to the pedestal portion 34A, so that the ceramic substrate 11 is surely attached. Such thermal stress can be reduced.
The heat sink has a suitable shape such as a flat plate, one in which a large number of pin-shaped fins are integrally formed by hot forging, etc., and one in which strip-like fins are formed integrally by extrusion. Can be adopted.

Next, the analysis result performed in order to confirm the effect of this invention is demonstrated.
As shown in FIGS. 5 (c) and 6 (b), in the conventional power module substrates 10C and 20C with a heat sink formed by the top plate portion 30C of the heat sink that does not have a concave groove portion, an accommodation recess 31 is formed. Even when the thickness t1 of the accommodating recess 31 immediately below the heat radiation layer 13 is formed to be thinner than the thickness t0 of the flange portion 32, it is greatly affected by the rigidity of the flange portion 32 during use. For this reason, the deformation resistance during use increases, and a load is applied to the ceramic substrate 11.

  Therefore, an analysis model of the power module substrates 10A to 10C with heat sinks shown in FIGS. 5A to 5C and an analysis model of the power module substrates 20A and 20C with heat sinks shown in FIGS. 6A and 6B. Was used, and the analysis which confirms the difference in the stress which arises at the time of using the groove part 33A, 33B in the accommodation recessed part 31 and the case where a groove part is not formed was performed.

  5A to 5C are analysis models corresponding to the first embodiment in which the circuit layer 12 of the power module substrate 15 constituting each of the power module substrates 10A to 10C with the heat sink is formed as a single layer. is there. 6 (a) and 6 (b) show that the circuit layer 12 of the power module substrate 16 constituting each of the power module substrates 20A and 20C with heat sink is formed by laminating the first metal layer 17 and the second metal layer 18. It is an analysis model corresponding to 2nd Embodiment formed with the structure.

5 (a) and 6 (a), the groove portion 33A is formed across the peripheral edge portion 13a of the heat radiating layer 13, that is, directly below the heat radiating layer 13, and the peripheral edge portion 13a is positioned in the middle of the width of the concave groove portion 33A. It is the model of the Example of this invention made to project to. FIG. 5B is an analysis model of a comparative example in which the groove 33B is formed from the position of the peripheral edge 13a to the outer peripheral side without protruding the peripheral edge 13a of the heat dissipation layer 13. FIG. 5C and FIG. 6B are analysis models of a conventional example that does not have a concave groove.
Conditions for each analysis model were set as follows.

[Analysis model conditions]
1. Circuit layer and first metal layer, heat dissipation layer; pure aluminum (purity 99.99 mass%)
Plane size: 70mm x 70mm
Thickness: 0.6mm
2. Ceramic substrate; Si ₃ N ₄ (silicon nitride)
Plane size: 72mm x 72mm
Thickness: 0.32mm
3. Second metal layer; A3003 series aluminum alloy Plane size; 66mm x 66mm
Thickness: 1.2mm
4). Heat sink top plate; A3003 series aluminum alloy Plane size; 80mm x 100mm
Total thickness (flange thickness t0); 4.0 mm
Thickness of housing recess t1; 1.2 mm
Thickness t2 of the groove portion: 0.6 mm
5. The size of the joining area between the heat dissipation layer and the pedestal Example (FIGS. 5A and 6A); 66 mm × 66 mm
Comparative example (FIG. 5B); 70 mm × 70 mm
Conventional example (FIGS. 5B and 6C); 70 mm × 70 mm

  About each of these analysis models, when heated to 300 ° C., which is close to the heating temperature in the semiconductor element mounting process, deformation that occurs in the power module substrate with a heat sink, and one surface of the ceramic substrate 11 (surface on the circuit layer side) ) And the stress generated on many surfaces (surface on the heat dissipation layer side). The analysis results are shown in Table 1. The analysis of each analysis model was performed for one region that was divided into four equal straight lines orthogonal to the figure center in plan view of the power module substrate with a heat sink.

As can be seen from the results in Table 1, by forming the concave groove portions 33A and 33B in the top plate portion, the maximum principal stress generated in the analysis model can be reduced as compared with the case where the concave groove portions are not formed. Further, as in the analysis model of the comparative example shown in FIG. 5B, compared to the case where the concave groove portion 33B is formed from the position of the peripheral portion 13a of the heat radiation layer 13 to the outer peripheral side so as not to be directly under the heat radiation layer 13. As shown in the analysis model of the embodiment shown in FIG. 5A, the groove 33A is formed immediately below the peripheral edge 13a of the heat radiation layer 13, and the peripheral edge 13a is protruded to the middle position of the width of the concave groove 33A. When the inner part excluding the peripheral part 13a and the surface of the pedestal part 34A were joined, the maximum principal stress could be greatly reduced.
Further, as in the analysis model shown in FIGS. 6A and 6B, the circuit layer 12 is formed by laminating the first metal layer 17 and the second metal layer 18, and a symmetrical structure is formed around the ceramic substrate 11. As a result, it was confirmed that the maximum principal stress could be further reduced.
Thus, by forming the housing recess 31 in the top plate portion 30A of the heat sink and forming the groove 33A on the bottom surface of the housing recess 31, warpage of the ceramic substrate can be reduced.

10A-10C Power module substrate with heat sink 11 Ceramic substrate 12 Circuit layer 13 Heat radiation layer 15, 16 Power module substrate 17 First metal layer 18 Second metal layer 20A, 20B Power module substrate with heat sink 30A-30C Heat sink top Plate part 31 Housing recess 32 Flange parts 33A, 33B Groove parts 34A, 34B Base 40 Mold resin 60 Semiconductor element 70 External connection lead frame

Claims (3)

A circuit layer is bonded to one surface of the ceramic substrate, and a heat sink is bonded to the other surface of the ceramic substrate via a heat dissipation layer,
The top plate portion of the heat sink is formed with an accommodation recess for accommodating at least a part of the heat dissipation layer,
On the bottom surface of the housing recess, a recessed groove is formed along the peripheral edge of the surface of the heat dissipation layer,
The peripheral edge of the surface of the heat dissipation layer is provided so as to protrude to a middle position of the width of the concave groove, and the inner portion excluding the peripheral edge and the surface of the pedestal surrounded by the concave groove on the bottom surface of the housing recess, Power module board with heat sink to which is bonded.   The power module substrate with a heat sink according to claim 1, wherein the circuit layer and the heat dissipation layer are formed of the same material in the same plane size. The circuit layer includes a first metal layer bonded to the ceramic substrate and a second metal layer formed in a plane size smaller than the first metal layer and bonded to a central portion of the surface opposite to the ceramic substrate. The heat dissipation layer is formed in the same plane size with the same material as the first metal layer,
The power module with a heat sink according to claim 1, wherein the top plate portion is formed of the same material as the second metal layer, and the surface of the pedestal portion is formed in the same plane size as the second metal layer. Substrate.

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