JP2020107652A - Electric circuit board and power module - Google Patents

Abstract

To improve heat radiation properties and low thermal stress properties of an electric circuit board.SOLUTION: An electric circuit board 10 comprises: an insulating substrate 1 that has a first principal surface 1A and a second principal surface 1B; a metal member 2; and a heat conduction member g1. The metal member joined to the first principal surface includes a first metal member 2A and a second metal member 2B that are separated across a gap a1 along a direction parallel to the first principal surface. The metal member joined to the second principal surface includes a third metal member 2D arranged at a position on the opposite side of the first metal member, and a fourth metal member 2E arranged at a position on the opposite side of the second metal member. The third metal member and the fourth metal member are joined to a heat conduction member arranged at a position on the opposite side of the gap. The heat conduction member (graphite) has properties including a larger thermal conductivity than that of the metal member and a smaller thermal expansivity than that of the metal member, with respect to at least a direction (X) separating the third metal member and the fourth metal member from each other.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an electric circuit board in which a metal plate as a wiring member is joined to an insulating substrate, and a power module using the electric circuit board.

Conventionally, as an electric circuit board used for an electronic device such as a power module in which electronic components such as an IGBT (Insulated Gate Bipolar Transistor) are mounted, for example, a metal material such as copper is formed on an upper surface of an insulating substrate made of a ceramic sintered body or the like. An electric circuit board to which a metal member (metal plate) made of is bonded is used.
As described in Patent Document 1, the joining of the insulating substrate and the metal member is performed by laminating the metal member on the insulating substrate via a brazing material and brazing.

Japanese Patent No. 2797011

2. Description of the Related Art In recent years, power modules have been required to be small in size and have high output with the background of development of electric vehicles and the like, and accordingly, the thickness of conductors in electric circuit boards for power modules has been increasing.
The thickening of the metal plate on which the electronic component is mounted increases the influence of thermal stress due to the thermal expansion of the metal plate.
In the future, as power modules are required to be smaller and have higher output, the operating temperature will rise and the thermal environment will change drastically as the thickness of metal plates increases.

As shown in FIGS. 17(a) and (b) as a power module, the metal member 2 (2A, 2B) is joined to the first main surface 1A of the insulating substrate 1 via the brazing material 3 to form the first main surface 1A. Consider a structure including an electric circuit board in which the metal member 2 (2C) is bonded to the second main surface 1B of the insulating substrate 1 which is the opposite surface via the brazing material 3. A circuit pattern is formed on the first main surface 1A, including a metal member 2A on which the electronic component 40 serving as a heat generating portion is mounted and another metal member 2B. On the first main surface 1A, the metal member 2A and the metal member 2B are separated by a gap a1 along a direction parallel to the first main surface 1A.
On the other hand, the metal member 2C is provided on the second main surface 1B. The metal member 2C is continuously provided in a range on the opposite side to the metal member 2A, the gap a1, and the metal member 2B on the first main surface 1A side. In order to connect the heat radiation component via the metal member 2C, the metal member 2C is thus provided in a large area.
In such a structure, the heat generated in the electronic component 40 easily spreads and propagates to the entire metal member 2C through the metal member 2A, the brazing material 3, the insulating substrate 1, and the brazing material 3 for heat dissipation. It is possible to improve the heat conductivity to the components and improve the heat dissipation of the power module.

However, thermal stress occurs due to the difference in thermal expansion coefficient between the insulating substrate 1 and the metal member 2. The thermal stress is first generated as a residual stress after brazing the metal member 2, and is also generated by the subsequent operation of the power module. Since there is a gap a1 on the first main surface 1A side and the second main surface 1B side corresponding to the gap a1 is continuous with the metal member 2C, thermal stress differs between the front and back of the insulating substrate 1, There may be a problem that the insulating substrate 1 is warped or a crack a2 is generated at an edge position of the brazing material 3 in the gap a1 as shown in FIG. 17(b).

In order to reduce the thermal stress as described above, it is conceivable that the metal member 2 has the same pattern on the front and back of the insulating substrate 1 as shown in FIG. 17(c).
However, in this case, as shown in FIG. 17(c), only the metal member 2D on the back of the metal member 2A on which the electronic component 40, which is the heat generating portion, is mounted becomes the main heat conducting portion, and the heat conducting area is reduced in area. Therefore, there is a problem that the heat dissipation is lowered.

An electric circuit board according to one aspect of the present disclosure includes an insulating substrate having a first main surface and a second main surface opposite to the first main surface, and a metal member bonded to the first main surface, A metal member joined to the second main surface, and a heat conducting member,
The metal member joined to the first main surface includes a first metal member and a second metal member separated by a gap along a direction parallel to the first main surface,
The metal member joined to the second main surface is a third metal member arranged at a position opposite to the first metal member, and a fourth metal member arranged at a position opposite to the second metal member. Including members,
The third metal member and the fourth metal member are joined to the heat conducting member arranged at a position opposite to the gap,
The heat-conducting member has characteristics that the heat conductivity is higher than that of the metal member and the coefficient of thermal expansion is lower than that of the metal member in at least the direction separating the third metal member and the fourth metal member.

According to the electric circuit board of the present disclosure, the heat conductivity of the heat conducting member is larger than that of the metal member, so that the heat conduction between the third metal member and the fourth metal member is good, and the heat dissipation is improved. Further, the thermal expansion coefficient of the heat conducting member is smaller than that of the metal member, so that the thermal stress is reduced. Therefore, an electric circuit board having good heat dissipation and low thermal stress, and a power module using the same are provided.

(a) is a sectional view showing an electric circuit board and an electronic component according to an embodiment of the present invention. (b) is a perspective view showing the orientation of graphite, which is a heat conducting member. It is sectional drawing which shows the electric circuit board and electronic component which concern on other one Embodiment of this invention. It is a top view of the electric circuit board concerning one embodiment of the present invention. It is a top view of the electric circuit board concerning the embodiment of other wiring patterns of the present invention. Illustration of the brazing material is omitted. It is a figure which shows the simulation result of the heat distribution which concerns on a comparative example and this invention example. It is a figure which shows the simulation result of the stress distribution which concerns on a comparative example and this invention example. It is a figure which shows the simulation result of the heat distribution which concerns on the example of this invention. It is a figure which shows the simulation result of the stress distribution which concerns on the example of this invention. It is a perspective view which shows a thermal simulation model. 10 is a table showing the heat transfer coefficient of each part of the model shown in FIG. 9. It is a perspective view which shows the half body part of a stress simulation model. 12 is a table showing the coefficient of thermal expansion, Young's modulus, and Poisson's ratio of each part of the model shown in FIG. 11. It is a figure which shows the simulation result of the stress distribution which concerns on the example of this invention. It is a perspective view showing an example of a power module. (a) is a top view of the power module shown in FIG. 14, (b) is sectional drawing in the CC line of (a). (a) And (b) is sectional drawing which shows another example of a power module. It is sectional drawing which shows the electric circuit board and electronic component which concern on a prior art example.

An electric circuit board and a power module according to embodiments of the present disclosure will be described with reference to the drawings. It should be noted that the distinction between upper and lower sides in the following description is for convenience, and does not limit the upper and lower sides when the electric circuit board is actually used.

[Electrical circuit board and power module]
As shown in FIG. 1A, an electric circuit board 10 according to the present embodiment includes an insulating substrate 1 and a metal member 2 (2A that is joined to a first main surface (upper surface) 1A of the insulating substrate 1 with a brazing material 3. , 2B), a metal member 2 (2D, 2E) joined by a brazing material 3 to a second main surface (lower surface) 1B opposite to the first main surface 1A, and a heat conducting member g1. .. The XY coordinates parallel to the insulating substrate 1 and the Z coordinate indicating the thickness direction of the insulating substrate 1 are illustrated. The first main surface (upper surface) 1A and the second main surface (lower surface) 1B are parallel to each other.

The metal member 2 is formed of copper, copper alloy, aluminum, aluminum alloy, or the like.
The metal member joined to the first main surface 1A includes a first metal member 2A and a second metal member 2B that are separated by a gap a1 along a direction (X direction) parallel to the first main surface 1A. including.
The metal member joined to the second main surface 1B is a third metal member 2D arranged at a position opposite to the first metal member 2A, and a fourth metal member arranged at a position opposite to the second metal member 2B. The member 2E is included.
An electronic component 40 is bonded and mounted on the first metal member 2A. The electronic component 40 is a power semiconductor device such as an IGBT.

The third metal member 2D and the fourth metal member 2E are joined via the brazing material 3 to the heat conducting member g1 arranged at a position opposite to the gap a1. That is, the side surface of the third metal member 2D and the side surface of the heat conducting member g1 are joined together via the brazing material 3, and the side surface of the fourth metal member 2E and the side surface of the heat conducting member g1 are joined together via the brazing material 3. doing.

The thermal conductive member g1 has a characteristic that the thermal conductivity is higher than that of the metal member 2 and the thermal expansion coefficient thereof is lower than that of the metal member 2. As a material having the same characteristics, graphite or a composite material containing graphite as a component is applied.
As graphite, one having a laminated structure manufactured by a chemical vapor deposition method is known. It is covalently bonded in the plane direction, the plane direction has high thermal conductivity, and the stacking direction has low thermal conductivity. As the composite material, a composite material of metal (copper, aluminum) and graphite can be applied. As shown in FIG. 1B, the heat conducting member g1 has a plane direction, which is a high heat conducting direction, in a direction parallel to the insulating substrate 1 (XY direction), and a stacking direction, which is a low heat conducting direction, is perpendicular to the insulating substrate 1. Are arranged in the direction (Z direction). Thereby, the heat conduction between the third metal member 2D and the fourth metal member 2E becomes good. Therefore, the heat generated in the electronic component 40 easily propagates to the metal member 2E via the heat conducting member g1 and the heat dissipation is improved.

Further, the thermal stress is reduced due to the characteristic that the thermal expansion coefficient of the heat conducting member g1 is smaller than that of the metal member. Therefore, the electric circuit board 10 having good heat dissipation and low thermal stress, and the power module using the same are provided.

As shown in FIG. 2, a structure in which the surface of the heat conducting member g1 that faces the second main surface 1B is joined to the second main surface 1B via the brazing material 3 may also be implemented. Furthermore, heat dissipation and low thermal stress can be improved.

As shown in FIG. 3, when the first main surface 1A is viewed vertically, the ends a3, a4 of the gap a1 in the direction Y perpendicular to the direction X in which the gap a1 separates the first metal member 2A and the second metal member 2B. However, it is possible to implement a structure in which the first metal member 2A and the second metal member 2B are left as separated.
In this case, it is possible to adopt a structure in which the end g2 (g3) of the heat conducting member g1 near the end a3 (a4) of the gap a1 is set back within the range of the gap a1.
By arranging the end a3 (a4) of the gap a1 near the corners of the first metal member 2A and the second metal member 2B where stress is likely to be concentrated in a plan view of the insulating substrate 1 also on the second main surface 1B side. The stress in this portion can be further reduced.
Generally, as shown in FIG. 3, the first metal member 2A and the second metal member 2B form a corner arc portion at the terminal end a3 (a4) of the gap a1 to relieve stress that tends to concentrate on the corner portion. When the first main surface 1A is viewed vertically, the end g2 (g3) of the heat conducting member g1 is set back within the gap a1 inside the corner arc portions 2A1, 2B1 (2A2, 2B2). Is preferred. This is to relieve stress that tends to concentrate on the corner arc portions 2A1, 2B1 (2A2, 2B2).

As shown in FIGS. 4(a)(b)(c), the first metal separated by a gap a1 along a direction parallel to the first principal surface 1A (direction of auxiliary lines d1, d2, d3). The structure of the member 2A and the second metal member 2 can also occur in a pattern in which the metal member 2 joined to the first main surface 1A is connected.
The pattern example of the metal member 2 shown in FIG. 4A has a structure in which the gap a1 ends when the metal members are connected on one side and ends while the metal members are separated on the other side.
The pattern example of the metal member 2 shown in FIG. 4B has a structure in which the corner portion of the metal member 2 is formed in a concave shape in order to relieve stress in the corner portion of the metal member 2.
The pattern example of the metal member 2 shown in FIG. 4(c) has a structure in which holes are formed in the corner portions of the metal member 2 in order to relieve stress in the corner portions of the metal member 2.
Even with the structure as described above, in the direction along the auxiliary lines d1, d2, d3, the gap a1 is formed on the first main surface 1A side and the heat conduction member g1 is formed between the metal members on the second main surface 1B side. By arranging so as to intervene, the effects of improving heat dissipation and reducing thermal stress are similarly obtained.

The insulating substrate 1 is preferably made of a ceramic sintered body and has characteristics such as high mechanical strength and high heat transfer characteristics (cooling characteristics). Known materials can be used as the ceramic sintered body, for example, alumina (Al ₂ O ₃ ) sintered body, aluminum nitride (AlN) sintered body, silicon nitride (Si ₃ N ₄ ) sintered body. A sintered body, a silicon carbide (SiC)-based sintered body, or the like can be used. Such an insulating substrate 1 can be manufactured by a known manufacturing method. For example, a raw material powder obtained by adding a sintering aid to alumina powder is kneaded with an organic binder or the like, and then molded into a substrate shape. It can be manufactured by firing.
As the brazing material 3, for example, when the metal member 2 is made of copper (Cu) or a copper alloy, a silver-copper (Ag-Cu) alloy brazing material, titanium (Ti), hafnium (Hf), zirconium ( Active metal brazes containing active metals such as Zr) can be used. When the metal member 2 is made of aluminum (Al) or an aluminum alloy, a brazing material of Al-Si alloy or Al-Ge alloy can be used.

A plating layer may be provided on the surface of the metal member 2 in order to protect the surface or improve the bondability of a bonding wire or the like. The plating layer can be a metal plating layer of palladium, nickel, silver or the like.
The electric circuit board 10 can also be manufactured by forming a so-called multi-cavity form and dividing it.

〔simulation〕
Next, thermal simulation and stress simulation will be disclosed.
(Simulation 1)
(Heat distribution)
FIG. 5 shows the simulation result of the heat distribution of the power module when the chip as the electronic component 40 is used as the heat generating portion. 5(a) is a comparative example C1 in which a metal member is continuously formed on the second main surface (lower surface) side of the portion corresponding to the gap a1, and FIG. 5(b) is the second main portion of the portion corresponding to the gap a1. In Comparative Example C2 in which the surface (lower surface) side is also the same, FIG. 5(c) shows the heat conduction member g1 on the second main surface (lower surface) side of the portion corresponding to the clearance a1 according to the embodiment (FIG. 2). Is a third example of the present invention D1 in which the graphite is placed in the direction shown in FIG. 1(b) and brazed to the third metal member 2D, the fourth metal member 2E and the second main surface (lower surface).
The highest temperature occurred at the exothermic center, which was 171.8° C. in Comparative Example C1, 178.4° C. in Comparative Example C2, and 171.1° C. in Inventive Example D1. In Comparative Example C2 as compared with Comparative Example C1, a gap was also provided on the second main surface (lower surface) side, which deteriorated heat transfer to the portion corresponding to the fourth metal member 2E, and further corresponded to the second metal member 2B. The maximum temperature increased due to the deterioration of heat transfer to the part.
In Example D1 of the present invention, heat propagates to graphite as the heat conductive member g1 and further propagates to the second metal member 2B via the fourth metal member 2E and the insulating substrate 1, so that heat is widely diffused, and comparison is made. The maximum temperature was lower than that of Example C1.
Therefore, it was found that the heat dissipation of the electronic component 40, which is the heat generating portion, was the best in the invention sample D1.

(Stress distribution)
FIG. 6 shows the simulation result of the stress distribution for the same model as in FIG.
Comparing the stress generated in the insulating substrate 1 at the center position of the gap a1 in the width direction, 784 MPa. The pressure was 0 MPa in Comparative Example C2 and 428 MPa in Invention Example D1.
In the comparative example C2 in which the gaps are at the same positions on the front and back, the stress was zero, but as shown in FIG. 5, the heat dissipation property deteriorates.
On the other hand, in Example D1 of the present invention, the heat dissipation was improved as shown in FIG. 5, and the stress generated in the insulating substrate 1 in the gap was also significantly reduced as compared with Comparative Example C1. ..

From the above simulation of heat distribution and stress distribution, it was found that the invention sample D1 was superior to the comparative samples C1 and C2 in heat dissipation and low thermal stress.

(Simulation 2)
In the present invention example, the heat distribution and the stress distribution were similarly simulated by changing the direction of graphite (g1). The results are shown in FIG. 7 (heat distribution) and FIG. 8 (stress distribution).
Inventive Example D1 shown in FIGS. 7(a) and 8(a) is a model in which graphite (g1) is arranged with the stacking direction, which is the low heat conduction direction, being perpendicular to the insulating substrate 1 (Z direction). Is. Therefore, FIG. 7A shows the same result as FIG. 5A, and FIG. 8A shows the same result as FIG. 6A.
The invention sample D2 shown in FIGS. 7(b) and 8(b) is a model in which graphite (g1) is arranged with the laminating direction, which is the low heat conduction direction, being the longitudinal direction (Y direction) of the gap a1. ..
The comparative example C3 shown in FIGS. 7(c) and 8(c) is a model in which graphite (g1) is arranged with the laminating direction, which is the low heat conduction direction, being the width direction (X direction) of the gap a1. ..
As shown in FIG. 7, the maximum temperature was 171.5° C. in Example D2 of the present invention and 173.1° C. in Comparative Example C3 as compared with 171.1° C. of Example D1 of the present invention.
Comparing the stress generated in the insulating substrate 1 at the center position in the width direction of the gap a1, it was 938 MPa in the invention sample D2 and 1610 MPa in the comparative sample C3, compared with 428 MPa of the invention sample D1.

FIG. 9 shows a model diagram of the above heat simulation, and FIG. 10 shows the heat transfer coefficient of each part. The metal member (Cu) on the lower surface of the electric circuit board is bonded to the heat sink 12 via the grease 11, the heat generation amount of the chip (40) is 200 W, and the heat transfer coefficient from the heat sink 12 to the air is 800 W/ m ² ·°C.
FIG. 11 shows a model diagram (half body diagram) of the above stress simulation, and FIG. 12 shows the thermal expansion coefficient, Young's modulus, and Poisson's ratio of each part.
The heat transfer coefficient and the thermal expansion coefficient of graphite (g1) differ depending on the direction. 10 and 12 show the heat transfer coefficient and the thermal expansion coefficient in the respective directions X, Y, Z in the cases of the present invention examples D1 and D2 and the comparative example C3.
As the graphite (g1), a material having a low thermal conductivity, a thermal conductivity in the stacking direction of 7 W/m·° C., and a high thermal conductivity, a thermal conductivity in the plane direction of 1700 W/m·° C. was applied. The graphite (g1) has a high coefficient of thermal expansion of 25 ppm/° C. in the low heat conduction direction (stacking direction) and a low coefficient of thermal expansion of −0.6 ppm/° C. in the high heat conduction direction (plane direction). Has a coefficient of thermal expansion of.

In the invention sample D2, as compared with the invention sample D1, since the low heat conduction direction was arranged in the Y direction as shown in FIG. 10, the maximum temperature slightly increased, but the third metal member 2D to the fourth metal member It is considered that the influence was small because the direction was not 2E (X direction).
On the other hand, in Comparative Example C3, the low heat conduction direction is arranged in the X direction as shown in FIG. 10, so that the direction from the third metal member 2D to the fourth metal member 2E (X direction) is the low heat conduction direction. Therefore, it is considered that the maximum temperature was further increased in the invention sample D2.

In the invention sample D1 as compared with the invention sample D1, the high thermal expansion direction was arranged in the Y direction as shown in FIG. 12, and the expansion in the X direction also occurred due to the Poisson's ratio, etc. did.
Further, in Comparative Example C3, the high thermal expansion direction was arranged in the X direction as shown in FIG. 12, so that the stress value also greatly increased compared to Invention Example D2.

From the results of the above simulation 2, as shown in FIG. 1B, the graphite (g1) has a low heat conduction direction in which the plane direction that is the high heat conduction direction is parallel to the insulating substrate 1 (XY direction). It has been found that it is preferable that the direction is set to be the direction (Z direction) perpendicular to the insulating substrate 1.
As in the invention examples D1 and D2, the thermal conductive member g1 has a thermal conductivity higher than that of the metallic member 2 and a thermal expansion coefficient of the metallic member at least in the direction X separating the third metallic member 2D and the fourth metallic member 2E. Advantageous results have been obtained with properties less than two.

(Simulation 3)
Between the heat conducting member g1 shown in FIG. 2 and the insulating substrate 1 according to an embodiment in which the heat conducting member g1 and the insulating substrate 1 are joined via the brazing filler metal 3, and the heat conducting member g1 and the insulating substrate 1 shown in FIG. The stress distribution was compared with invention sample D3 according to an embodiment where is a void. The results of the simulation are shown in FIG. 13A (invention sample D1) and FIG. 13B (invention sample D3). FIG. 13(a) is the same as FIG. 6(c) and FIG. 8(a).
Comparing the stress generated in the insulating substrate 1 at the center position of the gap a1 in the width direction, the stress increased to 492 MPa in the invention sample D4 compared to 428 MPa in the invention sample D1.
Since the graphite (g1) having a small coefficient of thermal expansion in the direction parallel to the insulating substrate 1 and the insulating substrate (Si ₃ N ₄ ) 1 are bonded to each other via the brazing filler metal ₃ , the deformation is reduced, so that the present invention It was found that the stress of the invention sample D1 was lower than that of the sample D3.
Therefore, the structure in which the surface of the heat conducting member g1 facing the second main surface 1B is joined to the second main surface 1B via the brazing material 3 is superior in terms of stress reduction. Do you get it.

[Other examples of power module]
Power modules 100, 101, 102 as described below can be implemented.
A power module is formed by mounting the power electronic components 40 on the electric circuit board 10. The three power modules 100, 101, 102 will be disclosed below.
The power module 100 is used, for example, in an automobile or the like, and is used in various control units such as an ECU (engine control unit), a power assist steering wheel, and a motor drive. The power module 100 is not limited to such a vehicle-mounted control unit, but is used for other various inverter control circuits, power control circuits, power conditioners, and the like.

In the power module 100 of the example shown in FIGS. 14 and 15, one electronic component 40 is mounted on the metal member 2 (121) joined to the central portion of the surface (upper surface) of the ceramic substrate (1). ing. The metal member 2 (122) arranged and bonded so as to sandwich the metal member 2 (121) on which the electronic component 40 is mounted and the electronic component 40 are electrically connected by the bonding wire 41. The metal member 2 (122) on the outer side functions as a terminal for connecting to an external electric circuit. Further, the heat generated in the electronic component 40 is bonded to the lower surface of the ceramic substrate (1) via the metal members 2 (121, 122) bonded to the upper surface of the ceramic substrate (1) and the ceramic substrate (1). The heat can be transmitted to the metal member 2 (123, 124) and the graphite (g1) and further radiated to the outside. That is, the composite of the metal member 2 (123, 124) and graphite (g1) bonded to the lower surface of the ceramic substrate (1) functions as a heat dissipation plate. The number, size and mounting position of the electronic components 40 are not limited to the examples shown in FIGS. 14 and 15.

The electronic component 40 is, for example, a power semiconductor and is used for power control in various control units as described above. For example, a transistor such as a MOS-FET (Metal Oxide Semiconductor-Field Effect Transistor) or IGBT using Si, or a power element using SiC or GaN can be used.
The electronic component 40 is bonded and fixed to the metal member 2 of the electric circuit board 10 by a bonding material (corresponding to 40a shown in FIG. 9). As the bonding material, for example, solder or silver nano paste can be used. When the metal coating is partially provided on the surface of the metal member 2, if the size of the electronic component 40 in plan view is smaller than the size of the metal coating, the fillet of the bonding material extends from the side surface of the electronic component 40 to the upper surface of the metal coating. Thus, the bonding strength of the electronic component 40 to the metal member 2 (metal coating) can be increased. Further, since the surface of the metal film is covered with the bonding material and is not exposed, the bonding property of the sealing resin 50 described later is improved.

The bonding wire 41 is a connection member that electrically connects a terminal electrode (not shown) of the electronic component 40 and the metal member 2. As the bonding wire 41, for example, one made of copper or aluminum can be used.
In the power module 101 of the example shown in FIG. 16A, the power module 100 of the example shown in FIGS. 14 and 15 is covered with the sealing resin 50 from the upper surface to the outer peripheral portion of the lower surface to seal the electronic component 40. It has been done. The sealing resin 50 does not cover the metal member 2 (123, 124) joined to the lower surface of the ceramic substrate (1) and the main surface (lower surface) of the graphite (g1). Therefore, the composite of the metal member 2 (123, 124) functioning as a heat dissipation plate and the graphite (g1) can be directly and thermally connected to an external heat dissipation body or the like, and thus the power module 101 having excellent heat dissipation performance. Can be The metal member 2 (122) functioning as a terminal has a length protruding from the insulating substrate 1 and also protruding from the sealing resin 50. As a result, the metal member 2 (122) functioning as a terminal can be easily electrically connected to an external electric circuit.
As the sealing resin 50, a thermosetting resin such as a silicone resin, an epoxy resin, a phenol resin, or an imide resin can be used from the viewpoints of thermal conductivity, insulation, environment resistance, and sealing property.

In the power module 102 of the example shown in FIG. 16B, the power module 100 of the example shown in FIGS. 14 and 15 is arranged in the internal space of the housing 60 having an inner space, and the sealing resin 50 is placed in the internal space. In this example, the electronic component 40 and the electric circuit board 10 are filled and sealed.
As in the example shown in FIGS. 16A and 16B, the power modules 101 and 102 can be provided with the sealing resin 50 that covers the electronic component 40, the metal member 2 and the insulating substrate 1. The sealing resin 50 improves the environmental resistance of the electronic component 40 and also improves the insulation between the adjacent metal plates 121 and 122.
The housing 60 includes a frame body 61 and a heat dissipation plate 62 that closes one opening of the frame body 61, and a space surrounded by the frame body 61 and the heat dissipation plate 62 is an inner space. In addition, a lead terminal 63 is provided that extends from the inner space to the outside through the frame 61 of the housing 60. Then, the ends of the lead terminals 63 in the internal space and the metal members 2 of the electric circuit board 10 are connected by the bonding wires 41. As a result, the electronic component 40 and the external electric circuit can be electrically connected.
The frame 61 is made of a resin material, a metal material, or a mixed material thereof, and one opening is closed by the heat dissipation plate 62 to form an inner space for housing the electric circuit board 10. The material used for the frame 61 is a metal material such as copper or aluminum or a resin such as polybutylene terephthalate (PBT) or polyphenylene sulfite (PPS) from the viewpoint of heat dissipation, heat resistance, environment resistance and light weight. Materials can be used. Among these, it is preferable to use the PBT resin from the viewpoint of easy availability. Further, it is preferable to add glass fibers to the PBT resin to obtain a fiber reinforced resin because the mechanical strength increases.

The lead terminal 63 is a conductive terminal that is attached so as to penetrate the frame 61 from the inner space and lead out to the outside. An end of the lead terminal 63 on the inner space side is electrically connected to the metal member 2 of the electric circuit board 10, and an end on the outer side is an external electric circuit (not shown) or a power supply device (not shown). It is electrically connected to. Various metal materials used for the conductive terminals of the lead terminal 63 may be Cu and Cu alloys, Al and Al alloys, Fe and Fe alloys, and stainless steel (SUS).
The heat dissipation plate 62 is for dissipating the heat generated in the electronic component 40 during operation to the outside of the power module 102. A high heat conductive material such as Al, Cu, or Cu—W can be used for the heat dissipation plate 62. In particular, Al has a higher thermal conductivity than a metal material as a general structural material such as Fe, and can dissipate the heat generated in the electronic component 40 to the outside of the power module 102 more efficiently. Can be stably operated normally. Further, Al is superior in that it is advantageous in reducing the cost of the power module 102 because it is easily available and inexpensive as compared with other high thermal conductivity materials such as Cu and Cu-W.

The heat dissipation plate 62, the metal members 2 (123, 124) of the electric circuit board 10 and the graphite (g1) are thermally connected by a heat conductive bonding material (not shown). As the heat conductive bonding material, a brazing material may be used to thermally connect and mechanically bond strongly, or grease may be used to thermally bond and mechanically bond relatively weakly. Further, they may be joined by the sealing resin 50 as described later.
The sealing resin 50 is filled in the inner space and seals and protects the electronic component 40 mounted on the electric circuit board 10. The same sealing resin 50 may be used to mechanically bond the electric circuit board 10 and the heat dissipation plate 62 and to seal the inner space. In this case, the mechanical and firm joining of the electric circuit board 10 and the heat dissipation plate 62 and the resin sealing can be performed in the same step.

In the power module 102, in order to further improve the heat dissipation characteristics, the cooler 70 is provided on the exposed surface of the heat dissipation plate 62 opposite to the side to which the electric circuit board 10 is bonded, with the heat conductive bonding material 71 interposed therebetween. May be joined together. As the heat conductive bonding material 71, the same heat conductive bonding material as described above that connects the heat dissipation plate 62 and the metal member 2 (123) of the electric circuit board 10 can be used. In the example shown in FIG. 16(b), the cooler 70 has a block body made of metal or the like provided with a flow path for allowing a coolant such as water to pass through. However, other than this, for example, a cooling fin may be used. Good. Such a cooler 70 can also be applied to the power modules 100 and 101 of the examples shown in FIG. 14 and FIG. 15 or FIG. It may be connected to the complex. In this case, a flat plate, that is, only the heat dissipation plate 62 shown in FIG. 16B can be applied as the cooler 70.
The electric circuit board 10 and the power module 100 are not limited to the examples described in the above embodiment, and various modifications can be made within the scope of the present disclosure.

DESCRIPTION OF SYMBOLS 1 Insulation board 1A 1st main surface 1B 2nd main surface 2 Metal member 2A 1st metal member 2B 2nd metal member 2D 3rd metal member 2E 4th metal member 2E Metal member 3 Brazing material 10 Electric circuit board 40 Electronic component C1 , C2, C3 Comparative examples D1, D2, D3 Inventive example a1 Gap g1 Heat conducting member (graphite)

Claims (11)

An insulating substrate having a first main surface and a second main surface opposite to the first main surface, a metal member joined to the first main surface, and a metal member joined to the second main surface. , And a heat conduction member,
The metal member joined to the first main surface includes a first metal member and a second metal member separated by a gap along a direction parallel to the first main surface,
The metal member joined to the second main surface is a third metal member arranged at a position opposite to the first metal member, and a fourth metal member arranged at a position opposite to the second metal member. Including members,
The third metal member and the fourth metal member are joined to the heat conducting member arranged at a position opposite to the gap,
The heat conducting member has an electric circuit board having a characteristic that the coefficient of thermal conductivity is larger than that of the metallic member and the coefficient of thermal expansion is smaller than that of the metallic member in at least the direction separating the third metallic member and the fourth metallic member. .. The electric circuit board according to claim 1, wherein a surface of the heat conducting member facing the second main surface is joined to the second main surface. When the first main surface is viewed vertically, the end of the gap in the direction perpendicular to the direction in which the gap separates the first metal member and the second metal member is the first metal member and the second metal. The electric circuit board according to claim 1 or 2, wherein the end of the heat conducting member, which is terminated as being separated from the member, close to the end of the gap is set back within a range within the gap. The first metal member and the second metal member form a corner arc portion at the end, and the end of the heat conducting member is more than the corner arc portion when the first main surface is viewed vertically. The electric circuit board according to claim 3, wherein the electric circuit board is arranged so as to recede within a gap. The electric circuit board according to claim 1, wherein the heat conductive member is made of graphite or a composite material containing graphite as a component. The heat conducting member is arranged such that a surface direction which is a high heat conducting direction is parallel to the second main surface and a laminating direction which is a low heat conducting direction is a direction perpendicular to the second main surface. The electric circuit board according to. The electrical circuit board according to any one of claims 1 to 6, wherein the joining of the insulating substrate and the metal member and the joining of the heat conducting member and the metal member are joining via a brazing material. .. The bonding between the insulating substrate and the metal member, the bonding between the heat conducting member and the metal member, and the bonding between the heat conducting member and the insulating substrate are bonding via a brazing material. Electrical circuit board. An electric circuit board according to any one of claims 1 to 8,
A power module comprising: an electronic component mounted on the first metal member. The power module according to claim 9, further comprising a sealing resin that seals the electronic component and the metal member on which the electronic component is mounted. The power module according to claim 9 or 10, wherein a heat dissipation component mounted on the metal member bonded to the second main surface is provided on the opposite surface of the electronic component via the insulating substrate.

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