JP4158648B2 - Semiconductor cooling unit - Google Patents

Description

  The present invention relates to a power conversion device provided with a cooling means for electronic components constituting a power conversion circuit.

2. Description of the Related Art Conventionally, for example, a semiconductor module containing a power semiconductor element such as an IGBT may be used in an inverter circuit that generates a drive current for energizing an AC motor that is a power source of an electric vehicle or a hybrid vehicle.
Generally, in an electric vehicle, a hybrid vehicle, or the like, a drive current to be energized tends to be a large current in order to obtain a large drive torque from an AC motor.
Therefore, in the semiconductor module that controls the drive current, the amount of heat generated from a power semiconductor element such as an IGBT becomes large.

Therefore, a semiconductor cooling unit in which a cooling means is provided in the semiconductor module has been proposed. In the semiconductor cooling unit, for the purpose of improving the heat dissipation efficiency, a device for ensuring a wide contact area between the heat dissipation surface of the semiconductor module and the cooling surface of the cooling means may be used.
For example, in order to promote heat dissipation from the semiconductor module, there is a semiconductor cooling unit in which the heat dissipation surface of the semiconductor module is formed in a convex shape and the heat dissipation surface is in contact with the cooling surface of the cooling means (for example, Patent Documents) 1).

The semiconductor cooling unit positively deforms the convex heat radiating surface according to the surface shape of the cooling surface by applying a contact load between the convex heat radiating surface and the cooling surface. It is constituted as follows.
And in the said semiconductor cooling unit, the contact area between both is ensured widely by contact | abutting a thermal radiation surface and a cooling surface as mentioned above.

However, the conventional semiconductor cooling unit has the following problems. In other words, the semiconductor module is distorted along with the deformation of the convex heat dissipation surface, and there is a possibility that trouble may occur in the internal semiconductor element itself, the solder joint portion, and the like.
That is, there is a risk of performance degradation due to characteristic fluctuations of the semiconductor element and durability degradation due to solder cracks at the solder joints.
Japanese Patent Laid-Open No. 10-340951

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a semiconductor cooling unit that achieves both high heat dissipation performance and long-term operation reliability.

The present invention relates to a semiconductor cooling unit comprising a combination of a semiconductor module including a power semiconductor element and a flat cooling tube having a hollow portion through which a coolant flows.
The semiconductor module has two flat electrode heat sinks facing each other so as to sandwich the semiconductor element, and is disposed between the pair of cooling tubes facing each other. ,
The cooling tube has a heat absorbing surface that directly or indirectly contacts the electrode heat sink,
The thickness of the tube wall forming the suction hot surface, Ri thinner Citea than the plate thickness of the electrode heat sink
In the semiconductor cooling unit, the electrode heat sink is formed of a copper alloy, and the cooling tube is formed of an aluminum alloy that is softer than the copper alloy forming the electrode heat sink. 1).

In the power conversion device of the present invention, the thickness of the tube wall is made thinner than the thickness of the electrode heat dissipation plate.
For this reason, when a contact load is applied between each of the cooling tubes and the semiconductor module, the semiconductor module is less likely to be distorted because the thin cooling plate tends to be deformed.
Therefore, in the power conversion device of the present invention, it is possible to ensure a wide contact area between the semiconductor module and the cooling tube while suppressing the possibility of causing trouble in the semiconductor module.

Therefore, the semiconductor cooling unit of the present invention is an excellent power conversion device that achieves both heat dissipation and reliability.
In addition, a thin insulating plate or an insulating film formed on the heat absorbing surface or the surface of the electrode heat dissipation plate is disposed as an electrically insulating layer between the heat absorption surface and the electrode heat dissipation plate. Thus, the two can be contacted indirectly.
Alternatively, the heat absorption surface and the electrode heat dissipation plate are brought into direct contact with each other, while the cooling tubes are electrically connected to other parts such as a refrigerant and other cooling tubes. It is also possible to insulate.

In the present invention, it is preferable to form the cooling tube from an aluminum alloy containing aluminum of 90% by weight or more.
Since the aluminum alloy is generally a soft metal material, the cooling tube can be easily deformed, and the risk of distortion of the semiconductor module can be relatively suppressed.
Furthermore, it is preferable to form the said electrode heat sink from the copper alloy containing copper 60% or more of weight ratio.
Since the copper alloy is generally a hard metal material, the electrode heat dissipating plate is useful for protecting a semiconductor element and the like housed in the semiconductor module.

Further, the thickness of the tube wall, it is not preferable that is thinner than 0.6 times the thickness of the electrode radiator plate.
In this case, the rigidity of the cooling tube can be further suppressed relative to the rigidity of the semiconductor module.
And the trouble of the said semiconductor module which may arise when a contact load is made to act between the said semiconductor module and the said cooling tube can further be suppressed.

Further, the thickness of the tube wall, it is not preferable that is thinner than 0.3 times the thickness of the electrode radiator plate.
In this case, the rigidity of the cooling tube can be further suppressed relative to the rigidity of the semiconductor module.
When a contact load is applied between the semiconductor module and the cooling tube, the cooling tube can be appropriately deformed to ensure a wide contact area between the two.

Further, the semiconductor cooling unit, the semiconductor module and the said cooling tubes are alternately stacked, at least it is preferable that the have a layer of two or more layers of the semiconductor module (claim 2).
In this case, in order to bring the semiconductor module and the cooling tube into contact with each other properly, it is necessary to increase the load in the stacking direction. Therefore, the effect of the present invention is particularly effective.

The cross-sectional shape of the absorbing surface in the direction perpendicular to the flow direction of the coolant is preferably a convex shape protruding toward the electrode radiating plate (claim 3).
In this case, both can be brought into contact with high reliability at the inner peripheral portion of the contact area between the cooling tube and the electrode heat sink.
The protrusion height of the endothermic surface is preferably about 20 μm to 100 μm. If the protruding height is less than 20 μm, there is a possibility that a wide contact area between the heat absorbing surface and the electrode heat radiating plate cannot be secured.
On the other hand, if the protruding height exceeds 100 μm, the required contact load becomes large, and the semiconductor module may be distorted by the corresponding contact load.

Moreover, it is preferable that the cross-sectional shape of the said heat absorption surface in the direction orthogonal to the flow direction of the said refrigerant | coolant is a substantially circular arc shape which makes the convex shape which protrudes toward the said electrode heat sink (Claim 4 ).
In this case, the load in the contact region between the cooling tube and the electrode heat sink can be appropriately distributed so as to be large at the center and small at the outer periphery.
Therefore, both can be contacted with no gap over the entire contact area between the cooling tube and the electrode heat sink.

Further, on the inner wall surface of the hollow portion which corresponds to the back surface of the heat-absorbing surface, it is preferable that is formed with ribs for partitioning the hollow portion along the flow direction of the refrigerant (claim 5).
In this case, the cooling performance of the semiconductor module can be further improved by improving the heat transfer efficiency between the cooling tube and the refrigerant.

(Example 1)
The semiconductor cooling unit 1 of this example will be described with reference to FIGS.
The semiconductor cooling unit 1 is a unit formed by combining a semiconductor module 10 including a power semiconductor element 11 and a flat cooling tube 20 having a hollow portion 21 through which a refrigerant flows.
The semiconductor module 10 has two flat plate heat sinks 15 facing each other so as to sandwich the semiconductor element 11 and is arranged between a pair of cooling tubes 20 facing each other. It is set up.
The cooling tube 20 has a heat radiating surface 200 that comes into contact with the electrode heat radiating plate 15 via an insulating member 30 having electrical insulation properties. The electrode heat dissipation plate 15 is thinner than the plate thickness b.
This content will be described in detail below.

As shown in FIG. 1, the semiconductor cooling unit 1 of the present example forms a part of a power conversion device (not shown) that generates a drive current to be supplied to a travel motor for an electric vehicle, for example, and an inverter in the power conversion device A circuit or a unit constituting all or part of a DC-DC converter circuit.
The semiconductor cooling unit 1 of this example includes a semiconductor module 10 that houses an IGBT element 11 that is a power semiconductor element.

In this example, as shown in FIG. 1, the semiconductor module 10 and the cooling tube 20 are alternately stacked to constitute a semiconductor cooling unit 1 having a multilayer stacked structure having at least two layers of the semiconductor module 10. It is.
That is, the semiconductor cooling unit 1 of this example is configured as a semiconductor laminated unit (hereinafter, referred to as a semiconductor laminated unit 1) in which three layers of semiconductor modules 10 are laminated.
In addition, as shown in FIG. 2, the semiconductor laminated unit 1 includes two semiconductor modules arranged in parallel between adjacent cooling tubes 10 and has six semiconductor modules as a whole. It becomes.

Moreover, in the semiconductor laminated unit 1 of this example, as shown in FIG.1 and FIG.2, as the insulating member 30 between the electrode heat sink 15 of the semiconductor module 10 and the heat radiating surface 200 of the cooling tube 20, it is 320 micrometers thick. A SiN ceramic plate is laminated.
Alternatively, a ceramic plate such as aluminum nitride or alumina can be used as the insulating member. Further, an insulating coating film made of aluminum nitride, SiN, alumina, DLC, or the like, or an insulating coating film made of an organic insulator such as polyimide can be used as the insulating member.

In addition, the said insulating member can be abbreviate | omitted and the heat sinking surface 200 and the electrode heat sink 15 can also be made to contact directly. In this case, it is necessary to ensure electrical insulation between each cooling tube 20 and other portions such as a refrigerant and other adjacent cooling tubes.
As a method of electrically insulating the cooling tube 20 and the refrigerant, there are a method of forming an insulating film on the inner peripheral wall of the hollow portion 21 and a method of employing a refrigerant having electrical insulation.
On the other hand, as a method of electrically insulating each cooling tube 20 from other parts, there is a method of providing electrical insulation to the bellows pipe 400 (FIG. 2) itself that connects each cooling tube 20. For example, there are a method of forming the bellows pipe 400 from a material having electrical insulation, a method of forming an insulating coating having electrical insulation on the surface of the bellows pipe 400, and the like.
In addition, a method such as arranging an electrically insulating member between the bellows pipe 400 and each cooling tube 20 may be employed.

As shown in FIG. 3, the semiconductor module 10 includes a pair of electrode heatsinks that face each other an IGBT element 11 that is a power semiconductor element and a flywheel diode element 12 that is necessary for smooth rotation of the motor. 15 is a module sandwiched between 15.
The semiconductor module 10 is formed by integrally molding two electrode heat dissipating plates 15 and the elements 11 and 12 in the gaps with a mold resin.
In this example, the electrode heat sink is made of a copper alloy containing 90% copper, and the thickness thereof is b.

As shown in FIG. 4, the semiconductor module 10 is formed by resin molding so that the electrode heat dissipation plate 15 is exposed on both sides thereof, and the exposed electrode heat dissipation plate 15 functions as a heat dissipation surface.
In FIG. 3, for ease of understanding of the relationship between the electrode heat dissipation plate 15, the external terminals 150 and 160, and the mold resin, the mold resin (portion indicated by a dotted line) is divided into upper and lower parts for convenience. is there.

In the semiconductor module 10, as shown in FIGS. 3 and 4, a power signal terminal that is integrated with each of the electrode heat dissipation plates 15 and a control signal terminal that is a terminal for a power signal and in the mold resin. The control terminal 160 is held. The power terminal 150 and the control terminal 160 are disposed to face each other in a plane parallel to the electrode heat radiating plate 15.
Therefore, in the semiconductor laminated unit 1 (FIG. 1) in which the semiconductor module 10 and the cooling tube 20 are laminated, the power terminal 150 protrudes from the front side of the semiconductor laminated unit 1 and the control terminal 160 protrudes from the back side. Can be made.

As shown in FIG. 1, the cooling tube 20 of the present example is a flat piping member 20 having a hollow portion 21 for flowing a refrigerant therein. In this example, the cooling tube was formed from an aluminum alloy containing 97% aluminum.
And this cooling tube 20 forms the heat absorption surface 200 which contact | abuts to the electrode heat sink 15 via the said insulating member 30 in a part of flat surface which makes the flat shape. The tube wall 210 forming the heat absorbing surface 200 has a plate thickness a of approximately 32% of the plate thickness b of the electrode heat sink.

The cooling tube 20 is formed by drilling through holes (not shown) for supplying and discharging refrigerant on flat surfaces near both ends. And as shown in FIG. 2, the tubular bellows pipe 400 which consists of aluminum which can be expanded-contracted in a length direction is joined to each through-hole of the adjacent cooling tube 20. As shown in FIG.
Further, sealing cap members 201 are joined to both ends of the cooling tube 20.

In the semiconductor laminated unit 1, as shown in FIG. 2, the bellows pipe 400 forms a header portion 41 for supplying refrigerant and a header portion 42 for discharging.
In other words, the bellows pipe 400 is arranged in the gap between the adjacent cooling tubes 20 and realizes communication between the hollow portions 21 of the adjacent cooling tubes 20. And the some bellows pipe 400 arrange | positioned in each gap | interval of the laminated | stacked cooling tube 20 forms each header part 41 and 42 of a refrigerant | coolant as a whole.

  Here, when the semiconductor module 10 is sandwiched between the cooling tubes 20, as shown in the figure, the semiconductor module 10 is cooled with the bellows pipes 400 of the header portions 41 and 42 extended. After being arranged between 20, the bellows pipes 400 are contracted to bring the cooling tube 20 and the semiconductor module 10 into close contact with each other.

Further, as shown in FIG. 5, the semiconductor laminated unit 1 of this example is configured to be assembled in combination with the guide unit 50. The guide unit 50 is configured to apply a load in the stacking direction to the assembled semiconductor stacked unit 1.
The guide unit 50 includes a base plate portion 51 that abuts on one end surface in the stacking direction of the semiconductor multilayer unit 1, a clamping plate portion 52 that abuts on the other end surface, and a base plate portion 51 and a clamping plate portion 52. It is a unit comprising a pair of guide portions 53 that hold a gap therebetween.

As shown in FIG. 5, a flange (not shown) for fixing to the base plate portion 51 is formed on the end surface of the guide portion 53 on the base plate portion 51 side in the longitudinal direction.
And the guide part 53 is comprised so that it may fix in the state standing upright with respect to this baseplate part 51 by fixing a flange to the baseplate part 51 with a volt | bolt.
The base plate part 51 forms refrigerant flow paths 511 and 512 communicating with the pair of header parts 41 and 42. When the semiconductor laminated unit 1 is assembled to the guide unit 50, the refrigerant flow paths 511 and 512 and the header parts are formed. 41 and 42 communicate with each other.

As shown in FIG. 5, the clamping plate portion 52 is configured to connect a pair of guide portions 53 arranged at a predetermined interval in a bridge shape.
The clamping plate portion 52 is formed by drilling bolt holes through which the fixing bolts are inserted at both ends thereof, and is fixed to the longitudinal end surfaces of the respective guide portions 53 by the bolts inserted into the bolt holes. It is configured.

As shown in FIG. 5, the clamping plate portion 52 has a contact portion 520 that contacts the end surface in the stacking direction of the semiconductor stacked unit 1 between the bolt holes at both ends.
The contact portion 520 is formed to be thicker than both end portions where the bolt holes are formed, and is configured to protrude toward the semiconductor multilayer unit 1 when fixed to the guide portion 53.
And this clamping plate part 52 is comprised so that a load may be applied toward the semiconductor lamination | stacking unit 1 from the contact part 520 according to the fastening torque of the volt | bolt at the time of bolting to the end surface of the guide part 53. is there.

That is, in the semiconductor laminated unit 1 of this example, as shown in FIG. 6, the contact load acting between the cooling tube 20 and the semiconductor module 10 can be adjusted by adjusting the tightening torque.
Therefore, in the semiconductor laminated unit 1 of this example, an appropriate contact load can be applied between the cooling tube 20 and the semiconductor module 10 by applying an appropriate load from the clamping plate portion 52.
Therefore, in the semiconductor laminated unit 1 of this example, as shown in FIG. 6, the tube wall 210 of the cooling tube 20 having a thin plate thickness is deformed following the surface shape of the electrode heat radiating plate 15 that abuts. The contact state between the heat radiating surface 200 and the electrode heat radiating plate 15 can be made appropriate.

The electrode heat radiating plate 15 is formed of a copper alloy, while the cooling tube 20 forming the heat absorbing surface 200 is formed of an aluminum alloy that is softer than the copper alloy forming the electrode heat radiating plate 15.
Therefore, when the electrode heat radiating plate 15 and the heat absorbing surface 200 are brought into contact with each other, deformation can be positively generated on the side of the cooling tube 20 forming the heat absorbing surface 200. 15 can be prevented from being deformed or distorted.
Therefore, according to the combination of the cooling tube 20 and the semiconductor module 10 of this example, there is little risk of causing distortion or the like in the semiconductor module 10, and a wide contact area between them can be secured.

Furthermore, as shown in FIG. 1, the semiconductor laminated unit 1 of this example has laminated | stacked in the state which has arrange | positioned the cooling tube 20 on both surfaces of the semiconductor module 10, and applied the load to the lamination direction.
Therefore, a load can be applied to the semiconductor module 10 equally from both sides in the stacking direction.
Therefore, in the semiconductor laminated unit 1 of this example, there is little possibility that a load will act on the semiconductor module 10 non-uniformly, and there is little possibility that the semiconductor module 10 will be distorted.
Therefore, the semiconductor module 10 of this example is less susceptible to cracks in the solder joints and fluctuations in element characteristics, and can achieve good durability.

(Example 2)
In this example, the cross-sectional shape of the cooling tube is changed based on the first embodiment. This example will be described with reference to FIG.
In the cooling tube of this example, as shown in the figure, the cross-sectional shape of the endothermic surface 200 in the direction perpendicular to the refrigerant flow direction faces the electrode heat radiating plate 15 in a state where no contact load acts on the endothermic surface 200. It is formed so as to exhibit a substantially arc shape protruding.

In particular, in the cooling tube 20 of this example, the position of the apex of the endothermic surface 200 and the arrangement position of the IGBT element 11 in the semiconductor module 10 are substantially matched. In this example, the protrusion height g of the heat absorbing surface 200 is 40 μm.
Therefore, at the position where the IGBT element 11 which is a heat source is disposed, the heat absorbing surface 200 and the electrode heat radiating plate 15 are reliably brought into contact with each other through the insulating member 30, and a wide contact area between the two is ensured. Can do.

(Example 3)
In this example, the shape of the hollow portion of the cooling tube is changed based on the first embodiment. This example will be described with reference to FIG.
In the hollow portion 21 of the cooling tube 20 of the present example, a plurality of ribs 22 are formed that divide the hollow portion 21 along the flow direction of the refrigerant.

The cross-sectional shape of each rib 22 in the direction orthogonal to the flow direction of the refrigerant has a bent line shape (wedge shape) protruding outward from the center side.
And in this example, the hollow part 21 forms the rib 22 so that it may form a line symmetrical shape in the width direction.
The rib 22 is formed with an elastic portion 225 that is easily elastically deformed at the bent portion 220, and is easily bent and deformed by the elastic deformation of the elastic portion 225. Then, the bending deformation of the rib 22 facilitates the deformation such that the convex endothermic surface 200 of the cooling tube 20 due to the load in the stacking direction approaches a flat surface.
That is, the heat absorbing surface 200 of the cooling tube 20 of this example can be easily deformed following the surface shape of the electrode heat radiating plate 15 when a contact load is applied to the electrode heat radiating plate 15.

Further, ribs 22 are formed in the hollow portion 21 of the cooling tube 20 of this example so as to form a line symmetrical shape in the width direction.
Therefore, the load distribution that acts on the electrode heat dissipation plate 15 from the cooling tube 20 is a line-symmetric distribution in the width direction.
Therefore, a load can be applied from the cooling tube 20 to the semiconductor module 10 in a well-balanced manner, and there is little possibility of causing distortion in the semiconductor module 10 due to an unbalanced contact load.

As described above, according to the cooling tube 20 of this example, the heat exchange efficiency between the refrigerant and the cooling tube 20 can be improved by the ribs 22 disposed in the hollow portion 21. Can be further promoted.
Furthermore, according to the rib 22 formed with the elastic portion 225, a wide contact area between the endothermic surface 200 and the electrode surface 15 can be ensured without inhibiting the deformation of the convex endothermic surface 200.

Sectional drawing which shows the cross-sectional structure of the semiconductor lamination | stacking unit (no load) in Example 1. FIG. FIG. 3 is a front view showing a semiconductor stacked unit in the first embodiment. FIG. 3 is an assembly diagram illustrating the structure of the semiconductor module according to the first embodiment. 1 is a perspective view showing a semiconductor module in Example 1. FIG. The front view which shows the semiconductor lamination | stacking unit assembled | attached to the guide unit in Example 1. FIG. Sectional drawing which shows the cross-section of the semiconductor lamination | stacking unit (with load) in Example 1. FIG. Sectional drawing which shows the cross-sectional structure of the semiconductor lamination | stacking unit (no load) in Example 2. FIG. Sectional drawing which shows the cross-sectional structure of the semiconductor lamination | stacking unit (no load) in Example 3. FIG.

Explanation of symbols

1 Semiconductor cooling unit (semiconductor laminated unit)
DESCRIPTION OF SYMBOLS 10 Semiconductor module 11 IGBT element 12 Flywheel diode element 20 Cooling tube 200 Endothermic surface 30 Insulating member 41, 42 Header part 400 Bellows pipe 50 Guide unit 51 Base plate part 52 Clamping plate part 53 Guide part

Claims (5)

In a semiconductor cooling unit formed by combining a semiconductor module including a power semiconductor element and a flat cooling tube having a hollow portion through which a coolant flows,
The semiconductor module has two flat electrode heat sinks facing each other so as to sandwich the semiconductor element, and is disposed between the pair of cooling tubes facing each other. ,
The cooling tube has a heat absorbing surface that directly or indirectly contacts the electrode heat sink,
The thickness of the tube wall forming the suction hot surface, Ri thinner Citea than the plate thickness of the electrode heat sink
The electrode cooling plate is made of a copper alloy, and the cooling tube is made of an aluminum alloy that is softer than the copper alloy forming the electrode heat sink . 2. The semiconductor cooling unit according to claim 1, wherein the semiconductor cooling unit is formed by alternately stacking the semiconductor modules and the cooling tubes, and has at least two layers of the semiconductor modules. 3. The semiconductor cooling unit according to claim 1, wherein a cross-sectional shape of the heat absorbing surface in a direction orthogonal to a flow direction of the refrigerant is a convex shape protruding toward the electrode heat radiating plate. 4. The semiconductor cooling unit according to claim 3, wherein a cross-sectional shape of the endothermic surface in a direction orthogonal to the flow direction of the refrigerant is a substantially arc shape projecting toward the electrode heat radiating plate. 5. The rib according to claim 1, wherein a rib that divides the hollow portion along a flow direction of the refrigerant is formed on an inner wall surface of the hollow portion that corresponds to a back surface of the heat absorbing surface. A semiconductor cooling unit.

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