Patent Application
20240387326
The embodiments discussed herein relate to a semiconductor device.
Semiconductor devices include a semiconductor module and a cooling device. The cooling device includes an inlet through which a refrigerant flows into the inside of the cooling device and an outlet through which the refrigerant flows out from the inside. In the cooling device, distribution pipes are individually connected to each of the inlet and the outlet. In addition, a pump is connected to each of the distribution pipes. The refrigerant flows into the cooling device from the inlet by the pump, then circulates through the cooling device, and flows out from the outlet. The discharged refrigerant is caused to flow into the cooling device again through the inlet by the pump. The semiconductor module is disposed on the cooling surface of the cooling device with the aforementioned configuration. The cooling device cools the semiconductor module that generates heat to thereby ensure the reliability of the semiconductor module (see, for example, Japanese Laid-open Patent Publication No. 2013-058518, Japanese Laid-open Patent Publication No. 2016-096272, International Publication Pamphlet No. WO 2011/132736, International Publication Pamphlet No. WO 2016/047335, and International Publication Pamphlet No. WO 2014/069174).
In addition, the semiconductor devices include a capacitor together with the semiconductor module. The capacitor is installed near the semiconductor module. On the other hand, the semiconductor devices have a problem in that the installation position of the capacitor is limited by where the distribution pipes of the cooling device are placed. Hence, the distribution pipes of the cooling device need to be connected in locations that do not interfere with the installation of the capacitor.
However, depending on the positions of the inlet and the outlet of the cooling device, the refrigerant introduced from the inlet may be unable to circulate throughout the inside of the cooling device, which may cause variations in cooling performance on the cooling surface of the cooling device. The reduced cooling performance may lead to improper cooling of the semiconductor module, which in turn may result in decreased output performance and reliability of the semiconductor devices.
According to an aspect, there is provided a semiconductor device, including: a semiconductor chip; and a cooling device having the semiconductor chip mounted thereon, wherein: the cooling device includes: a top plate having an upper surface on which the semiconductor chip is disposed and a lower surface opposite to the upper surface, and a cooling case having a rectangular shape in a plan view of the semiconductor device, and having a first outer lateral surface, a second outer lateral surface, a third outer lateral surface, and a fourth outer lateral surface sequentially disposed to form four sides thereof, the cooling case having a concave flow passage therein, the flow passage including a main passage, and an inflow passage that is recessed from a bottom surface of the main passage toward a bottom side of the cooling case that is opposite to a top side of the cooling case where the top plate is disposed, the cooling case further having an inlet, an opening of which is provided at the second outer lateral surface at a position closer to the third outer lateral surface than is the first outer lateral surface, the inlet being directly connected to the inflow passage and introducing a cooling medium that flows through the inlet in a longitudinal direction of the cooling case toward the flow passage, the inflow passage having a diffusion surface that faces the opening of the inlet.
The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention.
Several embodiments will be described below with reference to the accompanying drawings. Note that in the following the terms “front surface” and “top surface” refer to the X-Y plane facing upward (the +Z direction) in a semiconductor device 1 of
Next described is the semiconductor device 1 of a first embodiment with reference to
The semiconductor device 1 includes a semiconductor module 2 and a cooling device 3. The semiconductor module 2 includes semiconductor units 10a, 10b, and 10c and a case 20 for housing the semiconductor units 10a, 10b, and 10c. The semiconductor units 10a, 10b, and 10c housed in the case 20 are sealed with sealing members (not illustrated). Note that the semiconductor units 10a, 10b, and 10c all have the same configuration. Note that the term “semiconductor units 10” is used in the following description when no distinction is made among the semiconductor units 10a, 10b, and 10c. Details of the semiconductor units 10 will be described later.
The case 20 includes an outer frame 21; first connection terminals 22a, 22b, and 22c; second connection terminals 23a, 23b, and 23c; a U-phase output terminal 24a; a V-phase output terminal 24b; a W-phase output terminal 24c; and control terminals 25a, 25b, and 25c.
The outer frame 21 has a substantially rectangular shape in plan view, and is surrounded on all four sides sequentially by outer walls 21a, 21b, 21c, and 21d. In plan view, the outer walls 21a and 21c correspond to the long sides of the outer frame 21 while the outer walls 21b and 21d correspond to short sides of the outer frame 21. The corners at which the outer walls 21a, 21b, 21c, and 21d are connected to each other do not necessarily form right angles. They may be R-chamfered corners as illustrated in
The outer frame 21 includes unit housing parts 21e, 21f, and 21g disposed on the front surface along the outer walls 21a and 21c. The unit housing parts 21e, 21f, and 21g have a rectangular shape in plan view. The semiconductor units 10a, 10b, and 10c are housed in the unit housing parts 21e, 21f, and 21g, respectively.
The outer frame 21 is placed on a top surface 31 (see
On the front surface of the outer frame 21 in plan view, the first and second connection terminals 22a and 23a are located across the unit housing part 21e from the U-phase output terminal 24a in the ±Y direction. In the same manner, the first and second connection terminals 22b and 23b are located across the unit housing part 21f from the V-phase output terminal 24b, and the first and second connection terminals 22c and 23c are located across the unit housing part 21g from the W-phase output terminal 24c.
The outer frame 21 has, on its front surface, the first connection terminals 22a, 22b, and 22c and the second connection terminals 23a, 23b, and 23c provided on the outer wall 21a side in plan view. A first end, which is an outer end, of each of the first connection terminals 22a, 22b, and 22c and the second connection terminals 23a, 23b, and 23c is exposed to the front surface on the outer wall 21a side. Their second ends, which are inner ends, individually emerge inside the unit housing parts 21e, 21f, and 21g and are electrically connected to the semiconductor units 10a, 10b, and 10c.
The outer frame 21 includes, on its front surface, the U-phase output terminal 24a, the V-phase output terminal 24b, and the W-phase output terminal 24c on the outer wall 21c side. First ends, which are outer ends, of the U-phase output terminal 24a, the V-phase output terminal 24b, and the W-phase output terminal 24c are exposed to the front surface on the outer wall 21c side. On the other hand, their second ends, which are inner ends, individually emerge inside the unit housing parts 21e, 21f, and 21g and are electrically connected to the semiconductor units 10a, 10b, and 10c.
The outer frame 21 also has nuts housed in the lower part (in the −Z direction) of individual openings for the outer ends of the first connection terminals 22a, 22b, and 22c and the second connection terminals 23a, 23b, and 23c in such a manner that the nuts face the openings. Similarly, the outer frame 21 has nuts housed in the lower part of individual openings for the U-phase output terminal 24a, the V-phase output terminal 24b, and the W-phase output terminal 24c in such a manner that the nuts face the openings.
Further, the outer frame 21 is provided with the control terminals 25a, 25b, and 25c along the +Y direction sides (the outer wall 21c side) of the unit housing parts 21e, 21f, and 21g, respectively, in plan view. Each set of the control terminals 25a, 25b, and 25c is divided into two groups. The control terminals 25a, 25b, and 25c have a J-shape (or a U-shape). First ends, which are outer ends, of the control terminals 25a, 25b, and 25c extend vertically upward (in the +Z direction) from the front surface of the outer frame 21 on the outer wall 21c side. Their second ends, which are inner ends, are exposed vertically upward (in the +Z direction) from the front surface on the individual unit housing part 21e, 21f, and 21g sides. Note that the illustrated control terminals 25a, 25b, and 25c are merely an example, and appropriate changes may be made to their shape and number on an as-needed basis.
The outer frame 21 with the above-described configuration includes the first connection terminals 22a, 22b, and 22c, the second connection terminals 23a, 23b, and 23c, the U-phase output terminal 24a, the V-phase output terminal 24b, the W-phase output terminal 24c, and the control terminals 25a, 25b, and 25c. The outer frame 21 and these terminals are integrally formed by injection molding using a thermoplastic resin. In this manner, the case 20 is configured. As the thermoplastic resin, any of the following may be used, for example: a poly phenylene sulfide resin; a polybutylene terephthalate resin; a polybutylene succinate resin; a polyamide resin; and an acrylonitrile butadiene styrene resin.
The first connection terminals 22a, 22b, and 22c, the second connection terminals 23a, 23b, and 23c, the U-phase output terminal 24a, the V-phase output terminal 24b, the W-phase output terminal 24c, and the control terminals 25a, 25b, and 25c are made of a metal with excellent electrical conductivity. Such a metal is, for example, copper, aluminum, or an alloy containing at least one of these as a major component. Plating may be applied to coat the surfaces of the first connection terminals 22a, 22b, and 22c, the second connection terminals 23a, 23b, and 23c, the U-phase output terminal 24a, the V-phase output terminal 24b, the W-phase output terminal 24c, and the control terminals 25a, 25b, and 25c. In this case, a material used for plating is, for example, nickel, a nickel-phosphorus alloy, or a nickel-boron alloy.
The sealing member for sealing the unit housing parts 21e, 21f, and 21g may be a silicone gel or thermosetting resin. The thermosetting resin is, for example, epoxy resin, phenolic resin, maleimide resin, or polyester resin; however, epoxy resin is preferred. A filler may be added to the sealing member. The filler may be ceramic with insulation properties and high thermal conductivity.
The cooling device 3 includes the top plate 30 on which the above-described semiconductor module 2 is placed; and a cooling case 40 provided with an inlet and an outlet, on which the top plate 30 is disposed. A pump is connected to the cooling device 3 with the foregoing configuration. In the cooling device 3, a refrigerant, which is a cooling medium, is circulated by the pump. That is, the pump causes the refrigerant to be introduced into the cooling device 3 and then move around inside the cooling device 3. At this time, the refrigerant receives heat from the semiconductor module 2 to thereby cool the semiconductor module 2. The refrigerant having received heat is then discharged to the outside of the cooling device 3. In this manner, the refrigerant is circulated inside the cooling device 3 by the pump. Details of the cooling device 3 will be described later.
Next described are the semiconductor units 10a, 10b, and 10c with reference to
Each of the semiconductor units 10 includes an insulated circuit board 11, two semiconductor chips 12, and lead frames 13a and 13b. The semiconductor chips 12 are bonded to the insulated circuit board 11 with bonding members 14a. The lead frames 13a and 13b are bonded to main electrodes on the front surfaces of the semiconductor chips 12 with bonding members 14b. Note that, instead of the bonding members 14b, ultrasonic bonding may be used to bond the lead frames 13a and 13b to the insulated circuit board 11.
The insulated circuit board 11 includes an insulating plate 11a, wiring boards 11b1, 11b2, and 11b3, and a metal plate 11c. The insulating plate 11a and the metal plate 11c have a rectangular shape in plan view. In addition, the insulating plate 11a and the metal plate 11c may have R- or C-chamfered corners. The metal plate 11c is smaller in size than the insulating plate 11a in plan view, and is thus formed within the insulating plate 11a.
The insulating plate 11a is made of a material with insulation properties and excellent thermal conductivity. The insulating plate 11a may be made of ceramic. The ceramic here is, for example, aluminum oxide, aluminum nitride, or silicon nitride.
The wiring boards 11b1, 11b2, and 11b3 are formed on the front surface of the insulating plate 11a. The wiring boards 11b1, 11b2, and 11b3 are made of a metal with excellent electrical conductivity. The metal is, for example, copper, aluminum, or an alloy whose major component is at least one of these. Plating may be applied to coat the entire surfaces of the wiring boards 11b1, 11b2, and 11b3 in order to provide improved corrosion resistance. In this case, a material used for plating is, for example, nickel, a nickel-phosphorus alloy, or a nickel-boron alloy.
The wiring board 11b1 occupies half the area of the front surface of the insulating plate 11a on the +X direction side, and spreads across the entire region from the −Y direction side to the +Y direction side. To the area surrounded by the broken line indicated on the wiring board 11b1 in
The wiring board 11b2 occupies half the area of the front surface of the insulating plate 11a on the −X direction side. In addition, the wiring board 11b2 extends from the +Y direction side of the front surface of the insulating plate 11a to just short of the −Y direction side. To the area surrounded by the broken line indicated on the wiring board 11b2 in
The wiring board 11b3 occupies, on the front surface of the insulating plate 11a, an area surrounded by the wiring boards 11b1 and 11b2. To the area surrounded by the broken line indicated on the wiring board 11b3 in
The above-described wiring boards 11b1, 11b2, and 11b3 are formed on the front surface of the insulating plate 11a by the following means. For example, a metal layer is formed on the front surface of the insulating plate 11a and then subjected to etching or the like, to thereby obtain the wiring boards 11b1, 11b2, and 11b3 with predetermined shapes. Alternatively, the wiring boards 11b1, 11b2, and 11b3 preliminarily cut out of a metal layer are pressure bonded to the front surface of the insulating plate 11a. Note that the wiring boards 11b1, 11b2, and 11b3 are merely an example, and appropriate changes may be made to the number of the wiring boards 11b1, 11b2, and 11b3, their shapes, sizes and locations on an as-needed basis.
The metal plate 11c is formed on the rear surface of the insulating plate 11a. The metal plate 11c has a rectangular shape. The area of the metal plate 11c in plan view is smaller than that of the insulating plate 11a, but larger than the area where the wiring boards 11b1, 11b2, and 11b3 are formed. The metal plate 11c may have R- or C-chamfered corners. The metal plate 11c is smaller in size than the insulating plate 11a, and is formed on the entire surface of the insulating plate 11a except for the edges. The metal plate 11c is made of a metal with excellent thermal conductivity as a major component. The metal is, for example, copper, aluminum, or an alloy including at least one of these.
Examples of the insulated circuit board 11 having the above-described configuration include a direct copper bonding (DCB) board and an active metal brazed (AMB) board. The insulated circuit board 11 may be attached to the front surface of the cooling device 3 via a bonding member (not illustrated). This allows heat generated in the semiconductor chip 12 to be conducted to the cooling device 3 via the wiring boards 11b1 and 11b2, the insulating plate 11a, and the metal plate 11c and then radiated outwards.
The bonding members 14a and 14b are solder, for example. The solder used is lead-free solder. The lead-free solder contains, as a major component, an alloy containing at least two selected from tin, silver, copper, zinc, antimony, indium, and bismuth, for example. Further, the solder may include an additive, such as nickel, germanium, cobalt, or silicon. The inclusion of the additive increases wettability, brightness, and bond strength of the solder, which results in improved reliability.
The bonding member (not illustrated) for bonding the individual semiconductor units 10 and the cooling device 3 may be a brazing material or thermal interface material. The brazing material contains, as a major component, at least one selected from an aluminum alloy, a titanium alloy, a magnesium alloy, a zirconium alloy, and a silicon alloy, for example. The thermal interface material is an adhesive material, such as an elastomer sheet, room temperature vulcanization (RTV) rubber, gel, and a phase change material. Attachment of the semiconductor units 10 to the cooling device 3 via the foregoing brazing material or thermal interface material improves heat dissipation of the semiconductor units 10.
Each of the semiconductor chip 12 includes a power device element made of silicone. The power device element is, for example, a reverse-conducting insulated gate bipolar transistor (RC-IGBT). The RC-IGBT has integrated functions of both an IGBT, which is a switching element, and a free wheeling diode (FWD), which is a diode element. On the front surface of the semiconductor chip 12, control electrodes 12a (a gate electrode) and an output electrode (an emitter electrode), which is a main electrode 12b, are provided. On the rear surface of the semiconductor chip 12, an input electrode (a collector electrode), which is a main electrode, is provided. Note that the control electrodes 12a are laid out along one side of the front surface of the semiconductor chip 12 (or at the center of the one side). The output electrode is disposed at the center of the front surface of the semiconductor chip 12.
Note that, as the semiconductor chip 12, a pair of a switching element and a diode element may be used instead of an RC-IGBT. The switching element is, for example, an IGBT or power metal oxide semiconductor field effect transistor (power MOSFET). Such a semiconductor chip 12 has, for example, an input electrode (a drain or collector electrode) as a main electrode on the rear surface, and the control electrodes 12a (a gate electrode) and the output electrode (a source or emitter electrode) as the main electrode 12b on the front surface. On the other hand, the diode element is, for example, an FWD, such as a Schottky barrier diode (SBD) and a P-intrinsic-N (PiN) diode. Such a semiconductor chip 12 has an output electrode (a cathode electrode) as a main electrode on the rear surface, and an input electrode (an anode electrode) as a main electrode on the front surface.
The semiconductor chip 12 may include a switching element which is a power MOSFET whose major component is silicon carbide. Such a semiconductor chip 12 has the control electrodes 12a (a gate electrode) and the output electrode (a source electrode) as the main electrode 12b on the front surface, and an input electrode (a drain electrode) as a main electrode on the rear surface.
The lead frames 13a and 13b electrically connect the semiconductor chips 12 and the wiring boards 11b1, 11b2, and 11b3, to make wiring connections. Each of the semiconductor units 10 may be a device that serves as a single-phase inverter circuit. The lead frame 13a directly connects the main electrode 12b of the semiconductor chip 12 (on the wiring board 11b2) and the wiring board 11b3. The lead frame 13b connects the main electrode 12b of the semiconductor chip 12 (on the wiring board 11b1) and the wiring board 11b2.
The lead frames 13a and 13b integrally include the following respectively: main electrode bonding parts 13a1 and 13b1; first vertical linking parts 13a2 and 13b2; horizontal linking parts 13a3 and 13b3; second vertical linking parts 13a4 and 13b4; and wiring bonding parts 13a5 and 13b5. Note that the lead frames 13a and 13b have the same thickness throughout and are in the form of flat plates. The aforementioned individual parts of the lead frames 13a and 13b may be configured by bending. The lead frames 13a and 13b are made of a metal with excellent electrical conductivity. The metal is, for example, copper, aluminum, or an alloy whose major component is at least one of these. In order to provide improved corrosion resistance, plating may be applied to coat the entire surfaces of the lead frames 13a and 13b. In this case, a material used for plating is, for example, nickel, a nickel-phosphorus alloy, or a nickel-boron alloy.
The main electrode bonding parts 13a1 and 13b1 have a flat plate shape. The main electrode bonding parts 13a1 and 13b1 are joined to the main electrodes 12b of the semiconductor chips 12 (each provided on the wiring boards 11b2 and 11b1) with the bonding members 14b. Note that the main electrode bonding parts 13a1 and 13b1 have a rectangular shape in plan view, similar to the main electrodes 12b.
As for the first vertical linking parts 13a2 and 13b2, their lower ends are integrally connected to edges of the main electrode bonding parts 13a1 and 13b1, and their upper ends extend vertically upward (in the +Z direction) relative to the main electrode bonding parts 13a1 and 13b1. The first vertical linking part 13a2 is bonded to an edge portion of the main electrode bonding part 13a1 bonded to the semiconductor chip 12, which edge portion is located closer to the wiring board 11b3 (in the −Y direction). The first vertical linking part 13b2 is bonded to an edge portion of the main electrode bonding part 13b1 bonded to the semiconductor chip 12, which edge portion is located closer to the wiring board 11b2 (in the −X direction) in the −Y direction.
The horizontal linking parts 13a3 and 13b3 are integrally connected to the upper ends of the first vertical linking parts 13a2 and 13b2, and extend out over the wiring boards 11b3 and 11b2. At this time, the horizontal linking parts 13a3 and 13b3 straddle the gap between the wiring boards 11b2 and 11b3 and the gap between the wiring boards 11b1 and 11b2, respectively. The horizontal linking parts 13a3 and 13b3 are parallel to the insulated circuit board 11. In addition, the horizontal linking parts 13a3 and 13b3 may be the same in height.
As for the second vertical linking parts 13a4 and 13b4, their upper ends are integrally connected to the edges of the horizontal linking parts 13a3 and 13b3, and their lower ends extend vertically downward (in the −Z direction) and are integrally connected to the wiring bonding parts 13a5 and 13b5.
The wiring bonding parts 13a5 and 13b5 are joined to the wiring boards 11b3 and 11b2 and are integrally connected to the lower ends of the second vertical linking parts 13a4 and 13b4, respectively. Bonding of the wiring bonding parts 13a5 and 13b5 to the wiring boards 11b3 and 11b2 may be achieved using the aforementioned bonding members or by ultrasonic bonding.
The first vertical linking part 13a2, the horizontal linking part 13a3, the second vertical linking part 13a4, and the wiring bonding part 13a5 of the lead frame 13a have the same width. Note that the width here means the length in the direction (the ±X direction) perpendicular to the wiring direction (the ±Y direction) of the lead frame 13a. The first vertical linking part 13b2, the horizontal linking part 13b3, and the second vertical linking part 13b4 of the lead frame 13b have the same width. Note that the width here means the length in the direction (the ±Y direction) perpendicular to the wiring direction (the ±X direction) of the lead frame 13b.
The control electrodes 12a of the semiconductor chips 12 of the semiconductor units 10a, 10b, and 10c housed in the unit housing parts 21e, 21f, and 21f of the case 20 are mechanically and electrically connected to the inner ends of the control terminals 25a, 25b, and 25c by wires 26 (see
The cooling device 3 is explained next with reference to
Note that, in
A refrigerant is introduced into the cooling device 3, moves around inside the cooling device 3, and is then discharged to the outside. In this manner, the cooling device 3 cools the semiconductor module 2. Note that the refrigerant is a cooling medium, such as water, an antifreeze solution (ethylene glycol aqueous solution), and a long-life coolant (LLC). The cooling device 3 includes the top plate 30 and the cooling case 40. The cooling device 3 is made of a metal with excellent thermal conductivity as a major component. The metal is, for example, copper, aluminum, or an alloy including at least one of these. In order to provide improved corrosion resistance, plating may be applied to the cooling device 3. In this case, a material used for plating is, for example, nickel, a nickel-phosphorus alloy, or a nickel-boron alloy.
The top plate 30 has a rectangular flat plate shape in plan view. The top plate 30 includes the rectangular top surface 31 (cooling surface) (upper surface) and a lower surface 32 (fin installation surface) (lower surface) opposite and substantially parallel to the top surface 31. The top surface 31 and the lower surface 32 are flat and smooth. The top plate 30 also includes lateral surfaces 30a to 30d sequentially surrounding the top surface 31 and the lower surface 32 on all four sides. In plan view, the lateral surfaces 30a and 30c correspond to the long sides of the top plate 30, and the lateral surfaces 30b and 30d correspond to the short sides of the top plate 30. Each connection part (corners) of the lateral surfaces 30a to 30d may be R- or C-chamfered. In addition, the top plate 30 is formed with insertion holes 30g penetrating the top surface 31 and the lower surface 32. The insertion holes 30g are individually formed, in plan view, outside the corners of a cooling area 31d, which will be described later, on the top surface 31 of the top plate 30 and near the corners of the top surface 31 and the lower surface 32.
On the top surface 31, unit areas 31a to 31c are set along the X direction, in which the semiconductor units 10a to 10c, respectively, are disposed. The unit areas 31a to 31c each have a rectangular shape corresponding to the shape of the individual semiconductor units 10a to 10c. In addition, the top surface 31 is provided with the cooling area 31d. The cooling area 31d includes the unit areas 31a to 31c and has a rectangular shape. In plan view, the cooling area 31d is included in a flow passage area (main passage) 41 of a flow passage through which the cooling medium flows, which will be described later, when the top plate 30 is installed on the cooling case 40.
On the lower surface 32, multiple fins 33 are formed (see
Each of the multiple fins 33 may be a pin fin. In addition, each of the multiple fins 33 has a rectangular cross-section parallel to the lower surface 32 of the top plate 30.
In the X-Y plane of
The top plate 30 with the above-described multiple fins 33 provided thereon is formed, for example, by forging or casting (die-casting). In the case of forging, a block-shaped member containing the aforementioned metal with excellent conductivity as a major component is pressurized using a mold and then plastically deformed to obtain the top plate 30 with the multiple fins 33 formed thereon. In the case of die-casting, a molten die-casting material is poured into a predetermined casting mold and then cooled. After cooling, the casting is removed from the casting mold to obtain the top plate 30 with the multiple fins 33 formed thereon. The die-casting material used here is, for example, an aluminum alloy. Alternatively, the top plate 30 with the multiple fins 33 formed thereon may be made by cutting a block-shaped member whose major component is the aforementioned metal.
The cooling case 40 has a rectangular box shape in plan view. The cooling case 40 with such a shape includes a top surface 40e that is frame-shaped in plan view; and outer lateral surfaces 40a to 40d (first to fourth outer lateral surfaces) that sequentially surround the top surface 40e on all four sides.
The outer size of the top surface 40e is the same as that of the top plate 30. The flow passage area 41 having a concave shape is formed in the center of the top surface 40e. The flow passage area 41 is surrounded by the flow passage bottom surface 41e and inner lateral surfaces 41a to 41d (first to fourth inner lateral surfaces). The flow passage bottom surface 41e has a rectangular shape in plan view and is recessed from the top surface 40e (i.e., located in the −Z direction relative to the top surface 40e). The flow passage bottom surface 41e is substantially parallel to the top surface 40e. The inner lateral surfaces 41a to 41d sequentially surround, in plan view, the flow passage bottom surface 41e on all four sides and connect each side of the flow passage bottom surface 41e to the top surface 40e. The inner lateral surfaces 41a to 41d correspond to the outer lateral surfaces 40a to 40d, respectively. In plan view, the inner lateral surfaces 41a and 41c correspond to the long sides of the flow passage bottom surface 41e while the inner lateral surfaces 41b and 41d correspond to the short sides of the flow passage bottom surface 41e. The inner lateral surfaces 41a to 41d are substantially perpendicular to the flow passage bottom surface 41e and the top surface 40e. The top surface 40e and the inner lateral surfaces 41a to 41d are each flat and smooth. Each connection part (corner) of the inner lateral surfaces 41a to 41d as well as each connection part of the inner lateral surfaces 41a to 41d and the flow passage bottom surface 41e may be R-chamfered. The provision of the rounded surfaces ensures that the refrigerant introduced into the flow passage area 41 flows at each of the foregoing connection parts and thus prevents the refrigerant from stagnating at the connection parts, as described below. This in turn prevents the connection parts from corroding due to the refrigerant stagnation at the connection parts.
The top surface 40e is provided with a continuous ring-shaped sealing member 40f that surrounds the flow passage area 41 in plan view. The sealing member 40f is made of a material having an elastic member as a major component. Rubber is one example of such a material. The sealing member 40f is, for example, an 0 ring, a packing, or a gasket. The top surface 40e is also provided with fastening holes 40g. The fastening holes 40g are individually formed on the top surface 40e, in plan view, in the vicinity of each corner of the top surface 40e outside the flow passage area 41 and the sealing member 40f. That is, the fastening holes 40g are formed at locations corresponding to the insertion holes 30g when the top plate 30 is set on the top surface 40e. Note that the rear surface (not illustrated) opposite the top surface 40e is the rear surface of the cooling case 40. This rear surface also has a rectangular shape in plan view and is flat and smooth.
Each connection part of the outer lateral surfaces 40a to 40d as well as each connection part of the outer lateral surfaces 40a to 40d to the top surface 40e may be R-chamfered. In plan view, the outer lateral surfaces 40a and 40c correspond to the long sides of the top surface 40e while the outer lateral surfaces 40b and 40d correspond to the short sides of the top surface 40e. Note that the height of the outer lateral surfaces 40a to 40d (in the ±Z direction) is, for example, about 30 mm.
The inlet 40h is provided on at least one of the inner lateral surface 41b and a lateral surface 42b to be described later. An inflow channel 40h1 of the inlet 40h is formed that penetrates the cooling case 40 from the inner lateral surface 41b to the outer lateral surface 40b. In addition, a distribution pipe 44a is connected to the inflow channel 40h1 from the outer lateral surface 40b side without a gap. The penetrating direction of the inflow channel 40h1 (and the distribution pipe 44a) is substantially parallel to the inner lateral surfaces 41a and 41c (the ±X direction, i.e., the longitudinal direction) of the flow passage area 41. The inlet 40h faces an inflow area (inflow passage) 42, which is included in the flow passage and is described later. According to the first embodiment, the inlet 40h is formed, on the inner lateral surface 41b, at a position closer to the inner lateral surface 41c. Accordingly, the inflow channel 40h1 and the distribution pipe 44a are also formed, on the outer lateral surface 40b, at a position closer to the outer lateral surface 40c. The inlet 40h has, for example, a circular shape. The diameter of the inlet 40h in this case is about 10 mm, for example. Accordingly, the inflow channel 40h1 and the distribution pipe 44a have the same diameter as the inlet 40h.
In addition, an outlet 40i is provided on the inner lateral surface 41d. An outflow channel 40i1 of the outlet 40i is formed that penetrates the cooling case 40 from the inner lateral surface 41d to the outer lateral surface 40d. In addition, a distribution pipe 44b is connected to the outflow channel 40i1 from the outer lateral surface 40d side without a gap. The penetrating direction of the outflow channel 40i1 (and the distribution pipe 44b) is substantially parallel to the inner lateral surfaces 41a and 41c (the ±X direction, i.e., the longitudinal direction) of the flow passage area 41. According to the first embodiment, the outlet 40i is formed, on the inner lateral surface 41d, at a position closer to the inner lateral surface 41a. Accordingly, the outflow channel 40i1 and the distribution pipe 44b are also formed, on the outer lateral surface 40d, at a position closer to the outer lateral surface 40a. Note however that the outlet 40i may be formed near the corner on the opposite side to the inlet 40h across the center of the flow passage area 41. Therefore, the outlet 40i may be formed, on the inner lateral surface 41a, at a position closer to the inner lateral surface 41d. With respect to the position where the outlet 40i is provided, the outflow channel 40i1 and the distribution pipe 44b may also be formed, on the outer lateral surface 40a, at a position closer to the outer lateral surface 40d. The outlet 40i has, for example, a circular shape. The diameter of the outlet 40i in this case is about 10 mm, for example. Accordingly, the outflow channel 40i1 and the distribution pipe 44b have the same diameter as the outlet 40i.
In addition, the inflow area 42 is formed on the flow passage bottom surface 41e of the cooling case 40. The inflow area 42 is formed in the vicinity of the inlet 40h of the flow passage bottom surface 41e in plan view. The inflow area 42 is recessed in a concave shape from the flow passage bottom surface 41e, and communicates with the inlet 40h.
The inflow area 42 is surrounded by an inflow bottom surface 42e, lateral surfaces 42a to 42c, and the diffusion surface 42d. The inflow bottom surface 42e is recessed from the flow passage bottom surface 41e (located in the −Z direction relative to the flow passage bottom surface 41e) and has a rectangular shape in plan view. The inflow bottom surface 42e is substantially parallel to the flow passage bottom surface 41e.
The lateral surfaces 42a to 42c and the diffusion surface 42d sequentially surround, in plan view, the inflow bottom surface 42e on all four sides, and connect each side of the inflow bottom surface 42e to the flow passage bottom surface 41e. Note that, according to the first embodiment, the inflow area 42 is formed, relative to the flow passage area 41, in the vicinity of the corner formed by the inner lateral surfaces 41b and 41c in plan view. Accordingly, the lateral surfaces 42b and 42c of the inflow area 42 are flush with the inner lateral surfaces 41b and 41c, respectively. Therefore, the lateral surface 42a and the diffusion surface 42d connect the inflow bottom surface 42e and the flow passage bottom surface 41e. In plan view, the lateral surfaces 42a and 42c correspond to the long sides of the inflow bottom surface 42e while the lateral surface 42b and the diffusion surface 42d correspond to the short sides of the inflow bottom surface 42e.
The lateral surfaces 42a to 42c and the diffusion surface 42d are substantially perpendicular to the inflow bottom surface 42e and the flow passage bottom surface 41e. That is, the lateral surfaces 42a to 42c and the diffusion surface 42d are substantially perpendicular to a plane substantially parallel to the top surface 31 of the top plate 30. Note that the lateral surface 42a may be at an angle of 90° or more and 125° or less to the inflow bottom surface 42e. That is, the lateral surface 42a may be at an angle of 90° or more and 125° or less to the transverse direction (the −Y direction). When the lateral surface 42a is at an angle of less than 90° to the inflow bottom surface 42e, the refrigerant flowing through the inflow area 42 becomes difficult to flow from the inflow area 42 to the flow passage bottom surface 41e. On the other hand, if the lateral surface 42a is at an angle of more than 125° to the inflow bottom surface 42e, when the top plate 30 is attached to the cooling case 40, the refrigerant may fail to hit the multiple fins 33 on the inner lateral surface 41c side, as described below.
In addition, the diffusion surface 42d may preferably be perpendicular to the inflow bottom surface 42e and the flow passage bottom surface 41e. Note that the diffusion surface 42d may be inclined in side view (i.e., when viewed in the ±Y direction). The inclination in this case is, for example, 85° or more and 95° or less. That is, the diffusion surface 42d is inclined at an angle of 85° or more and 95° or less to a plane substantially parallel to the top surface 31 of the top plate 30.
The inflow bottom surface 42e, the lateral surfaces 42a to 42c, and the diffusion surface 42d are individually flat and smooth. In addition, each connection part (corner) of the lateral surfaces 42a and 42c and the diffusion surface 42d to each other as well as each connection part of the lateral surfaces 42a to 42c and the diffusion surface 42d to the inflow bottom surface 42e may be R-chamfered. The provision of the rounded surfaces ensures that the refrigerant introduced into the inflow area 42 flows at each connection part and thus prevents the refrigerant from stagnating at the connection parts, as described below. This in turn prevents the connection parts from corroding due to the refrigerant stagnation at the connection parts.
In addition, the diffusion surface 42d preferably faces the inlet 40h, as illustrated in
A length L2 spanning from the inlet 40h to the diffusion surface 42d may be about one third of a length L1 of the individual inner lateral surfaces 41a and 41c of the flow passage area 41 (the length from the inlet 40h to the inner lateral surface 41d). If being too close to the inlet 40h, the diffusion surface 42d blocks the inlet 40h. In this case, the refrigerant introduced from the inlet 40h becomes clogged at the diffusion surface 42d and is difficult to properly spread in the flow passage area 41. On the other hand, if the diffusion surface 42d is too far away from the inlet 40h, the flow of the refrigerant introduced from the inlet 40h significantly stalls before reaching the diffusion surface 42d. In this case, even if having reached the diffusion surface 42d, the refrigerant is not sufficiently diffused by the diffusion surface 42d, which is thus ineffective. In view of the above, the length L2 associated with the diffusion surface 42d may preferably be 5% or more and 30% or less of the length L1, and more preferably 5% or more and 15% or less. For example, when the length L1 is 120 mm, the length L2 may preferably be 30 mm, and more preferably 15 mm.
Note that the inlet 40h may be parallel to the diffusion surface 42d and partially overlap the diffusion surface 42d when viewed in the +X direction. For example, as illustrated in
The cooling case 40 described above is formed, for example, by forging or casting (die-casting). In the case of forging, a block-shaped member containing the aforementioned metal with excellent conductivity as a major component is pressurized using a mold and then plastically deformed to obtain the cooling case 40. In the case of die-casting, a molten die-casting material is poured into a predetermined casting mold and then cooled. After cooling, the casting is removed from the casting mold to obtain the cooling case 40. The die-casting material used here is, for example, an aluminum alloy. Alternatively, the cooling case 40 may be made by cutting a block-shaped member whose major component is the aforementioned metal. In addition, the distribution pipes 44a and 44b may be manufactured separately and joined to the inflow channel 40h1 and the outflow channel 40i1 of the cooling case 40 by welding.
The lower surface 32 of the top plate 30 is attached to the top surface 40e of the cooling case 40 with the above-described configuration (see, for example,
Note that the inlet 40h (as well as the inflow channel 40h1 and the distribution pipe 44a) and the outlet 40i (as well as the outflow channel 40i1 and the distribution pipe 44b) may be swapped to configure the cooling device 3. That is, the outlet 40i may be provided, on the inner lateral surface 41b, at a position closer to the inner lateral surface 41c while the inlet 40h may be provided, on the inner lateral surface 41d, at a position closer to the inner lateral surface 41a. In this case, the inflow area 42 is also provided in such a manner as to include the inlet 40h near the corner formed by the inner lateral surfaces 41a and 41d of the flow passage area 41.
Here, as a reference example, the cooling device 3 (cooling case) with no inflow area 42 formed therein is described using
When introduced from the distribution pipe 44a of the cooling case 140, the refrigerant moves through the distribution pipe 44a and the inflow channel 40h1 and then flows into the flow passage area 41 from the inlet 40h. That is, the refrigerant flows into the flow passage area 41 as travelling parallel to the inner lateral surfaces 41a and 41c (in the +X direction, i.e., the longitudinal direction).
The refrigerant having flowed in from the inlet 40h moves in the X direction and the −Y direction (toward the vicinity of the corner formed by the inner lateral surfaces 41a and 41d) as traveling in the flow passage area 41 in the +X direction to thus spread inside the flow passage area 41. Then, the refrigerant spreads toward the outlet 40i.
However, because the refrigerant spreads inside the flow passage area 41 in plan view in the above-described manner, it is difficult to flow through a region A surrounded by the broken line in
Thus, variations in cooling performance occur on the top surface 31 of the top plate 30 of the cooling device 3 that includes the cooling case 140. This prevents proper cooling of the semiconductor module 2 disposed on the cooling device 3.
Next described is the flow of the refrigerant of the cooling device 3 according to the first embodiment, with reference to
When introduced from the distribution pipe 44a of the cooling case 40, the refrigerant moves through the distribution pipe 44a and the inflow channel 40h1 and then flows into the inflow area 42 from the inlet 40h. That is, the refrigerant flows into the inflow area 42 as travelling parallel to the inner lateral surfaces 41a and 41c (in the +X direction, i.e., the longitudinal direction).
When moving straight through the inflow area 42 in the +X direction, the refrigerant hits the diffusion surface 42d. A part of the refrigerant goes over the diffusion surface 42d and proceeds directly to the inner lateral surface 41d. In addition, a part of the refrigerant having hit the diffusion surface 42d is diffused by the diffusion surface 42d. The diffused refrigerant spreads from the diffusion surface 42d in the −Y direction (toward the inner lateral surface 41a and the outer lateral surface 40a) as well as in the −Y and −X direction (toward the vicinity of the corner formed by the inner lateral surfaces 41a and 41b (the outer lateral surfaces 40a and 40b)). That is, the refrigerant flows through the region A of
The refrigerant passing beyond the diffusion surface 42d and proceeding directly to the inner lateral surface 41d travels straight in the +X direction within the flow passage area 41 and also moves in the X and −Y direction (toward the corner formed by the inner lateral surfaces 41a and 41d), to thus spread inside the flow passage area 41. Then, the refrigerant spreads toward the outlet 40i.
In light of the above, even if the inlet 40h (and the distribution pipe 44a) and the outlet 40i (and the distribution pipe 44b) are provided on the inner lateral surface 41b (and the outer lateral surface 40b) and the inner lateral surface 41d (and the outer lateral surface 40d), which are the short sides, variations in cooling performance depending on the position on the top plate 30 of the cooling device 3 do not occur and, therefore, uniform cooling performance is achieved and the problem of reduced cooling performance is thus improved. As a result, vacant space is created on the sides of the outer lateral surfaces 40a and 40c of the cooling device 3. That is, while improving the problem of reduced cooling performance of the cooling device 3, it is possible to place a capacitor on either side of the outer lateral surfaces 40a and 40c of the cooling device 3. The capacitor allows to be placed adjacent to the semiconductor module 2, which facilitates connection of the capacitor and the semiconductor module 2.
The general flow route of the refrigerant having flowed into the flow passage area 41 from the inlet 40h is such that the refrigerant enters the flow passage area 41 as travelling parallel to the inner lateral surfaces 41a and 41c (in the +X direction, i.e., the longitudinal direction), and spreads parallel to the inner lateral surfaces 41b and 41d (in the −Y direction, i.e., the transverse direction) within the flow passage area 41. Because the refrigerant proceeds in the transverse direction when it spreads inside the flow passage area 41, the refrigerant spreads over the flow passage area 41 while reducing pressure drop.
The refrigerant introduced from the inlet 40h moves through flow passages between the multiple fins 33 in the flow passage area 41 and then flows out from the outlet 40i. Herewith, the semiconductor module 2 disposed on the cooling device 3 is cooled.
The above semiconductor device 1 includes the semiconductor chips 12; and the cooling device 3 on which the semiconductor chips 12 are mounted. The cooling device 3 includes the top plate 30 including the top surface 31 on which the semiconductor chips 12 are placed and the lower surface 32 opposite the top surface 31; and the cooling case 40. In the cooling case 40, the flow passage area 41 is formed on the top surface 40e having a rectangular shape in plan view and surrounded on all four sides sequentially by the outer lateral surfaces 40a to 40d. The flow passage area 41 has a concave shape and includes the flow passage bottom surface 41e recessed from the top surface 40e. The lower surface 32 of the top plate 30 is disposed on the top surface 40e to thereby close the flow passage area 41 with the top plate 30. In addition, in plan view, the cooling case 40 has the outer lateral surfaces 40a and 40c spanning the long sides and the outer lateral surfaces 40b and 40d spanning the short sides. The inlet 40h communicating with the flow passage area 41 is formed, on the inner lateral surface 41b corresponding to the outer lateral surface 40b, at a position closer to the inner lateral surface 41c. A cooling medium is introduced and flows through the inlet 40h in the longitudinal direction toward the flow passage area 41. In addition, the inflow area 42 is formed, on the flow passage bottom surface 41e, at a position closer to the inlet 40h. The inflow area 42 is recessed in a concave shape from the flow passage bottom surface 41e and communicates with the inlet 40h. The inflow area 42 includes the diffusion surface 42d opposing the inlet 40h.
Herewith, the refrigerant introduced from the inlet 40h moves straight through the inflow area 42 in the +X direction and then hits the diffusion surface 42d. A part of the refrigerant goes over the diffusion surface 42d and proceeds directly to the inner lateral surface 41d. In addition, a part of the refrigerant having hit the diffusion surface 42d is diffused by the diffusion surface 42d. The diffused refrigerant spreads from the diffusion surface 42d toward the outer lateral surface 40a as well as toward the vicinity of the corner formed by the outer lateral surfaces 40a and 40b. The refrigerant having travelled in this manner then proceeds toward the outlet 40i. The refrigerant having gone over the diffusion surface 42d and proceeded directly to the inner lateral surface 41d moves straight in the +X direction in the flow passage area 41 and also proceeds to the vicinity of the corner formed by the inner lateral surfaces 41a and 41d to hereby spread inside the flow passage area 41. The refrigerant eventually spreads toward the outlet 40i. Therefore, the refrigerant flows throughout the flow passage area 41, which suppresses variations in cooling performance depending on the position on the top plate 30 of the cooling device 3 and enables uniform cooling over the top plate 30. In addition, the semiconductor device 1 has the inlet 40h on the outer lateral surface 40b side, which allows the capacitor to be installed on the side of the outer lateral surface 40a or 40c of the cooling device 3, adjacent to the semiconductor chips 12. Therefore, in the semiconductor device 1, it is possible to install the capacitor in an area suitable for the semiconductor chips 12 and improve the problem of reduced cooling performance of the cooling device 3, thereby preventing decreased reliability of the semiconductor device 1.
In Modification 1-1, a modification of the inflow area 42 included in the cooling device 3 described above is explained with reference to
The diffusion surface 42d may be inclined at an acute angle to the lateral surface 42a in plan view, as illustrated in
In addition, the lateral surface 42a may be inclined at an acute angle to the diffusion surface 42d in plan view, as illustrated in
In Modification 1-2, a modification of the inflow area 42 included in the cooling device 3 described above is explained with reference to
Guide walls 42g are formed on the inflow bottom surface 42e of the inflow area 42 of the cooling case 40 according to Modification 1-2. The guide walls 42g are formed to extend in the +Z direction with respect to the inflow bottom surface 42e. The guide walls 42g may each have a surface opposing the inner lateral surface 41b (the inlet 40h). The guide walls 42g may be inclined in the same manner as the diffusion surface 42d.
The refrigerant introduced from the inlet 40h moves straight through the inflow area 42 in the +X direction. At this time, a part of the refrigerant is guided in the −Y direction by the guide walls 42g. Therefore, the refrigerant more reliably spreads from the inflow area 42 toward the inner lateral surface 41a (the outer lateral surface 40a) as well as toward the vicinity of the corner formed by the inner lateral surfaces 41a and 41b (the outer lateral surfaces 40a and 40b), compared to the case where only the diffusion surface 42d is provided in the inflow area 42.
Note that the guide walls 42g of
The guide walls 42g of
If the width of the guide walls 42g in the ±Y direction is about the same as the width of the diffusion surface 42d in the same direction, the guide walls 42g prevent most of the refrigerant from moving straight. In addition, if the width of the guide walls 42g in the ±Y direction is too narrow compared to the width of the diffusion surface 42d in the same direction, the guiding effect on the refrigerant is reduced. In view of the above, the width of the guide walls 42g in the ±Y direction may be 45% or more and 55% or less, for example, 50%, of the width of the diffusion surface 42d in the same direction.
The cooling case 40 of the cooling device 3 according to a second embodiment is described using
The cooling case 40 of the second embodiment differs from the cooling case 40 of the first embodiment in having a groove part 42f therein. The configuration of the cooling case 40 of the second embodiment is the same as that of the cooling case 40 of the first embodiment other than the groove part 42f.
The groove part 42f is formed in the flow passage area 41 in such a manner as to extend, in plan view, from the diffusion surface 42d of the inflow area 42 to the inner lateral surface 41d along the inner lateral surface 41c (in the +X direction, that is, the longitudinal direction). The width of the groove part 42f in the ±Y direction is equal to the width of the inflow area 42 in the same direction. In addition, the groove part 42f is defined by a groove bottom surface 42f1, a groove lateral surface 42f2, and the inner lateral surfaces 41c and 41d.
The groove bottom surface 42f1 is connected to the diffusion surface 42d, extends along the inner lateral surface 41c (in the longitudinal direction) toward the inner lateral surface 41d, and is then connected to the inner lateral surface 41d. The groove bottom surface 42f1 is located, in the ±Z direction, lower than the flow passage bottom surface 41e and higher than the inflow bottom surface 42e. In addition, the groove bottom surface 42f1 is substantially parallel to the flow passage bottom surface 41e and the inflow bottom surface 42e. The entire groove bottom surface 42f1 is flat and smooth. Note that if the depth of the groove bottom surface 42f1 from the flow passage bottom surface 41e is too sharrow, the refrigerant does not travel straight along the groove part 42f. On the other hand, if it is too deep, the refrigerant traveling straight in the groove part 42f becomes difficult to flow out to the flow passage area 41. Therefore, the depth of the groove bottom surface 42f1 from the flow passage bottom surface 41e may preferably be 10% or more of the depth of the inflow bottom surface 42e from the flow passage bottom surface 41e.
The groove lateral surface 42f2 extends to the inner lateral surface 41d, running parallel to the inner lateral surface 41c (in the longitudinal direction). The groove lateral surface 42f2 connects the groove bottom surface 42f1 to the flow passage bottom surface 41e. Note that the second embodiment depicts a case where the groove lateral surface 42f2 is perpendicular to the groove bottom surface 42f1 and the flow passage bottom surface 41e; however, the groove lateral surface 42f2 may be inclined at an obtuse angle to the groove bottom surface 42f1. That is, the groove lateral surface 42f2 may be inclined at an obtuse angle to the transverse direction. This prevents eddy currents from being possibly induced when the groove lateral surface 42f2 is perpendicular to the groove bottom surface 42f1. Note however that if the inclination is too large, there is a risk that the refrigerant flowing out from the groove lateral surface 42f2 may fail to hit the multiple fins 33. For this reason, the inclination angle is, for example, greater than 90° and less than or equal to 125°. That is, the groove lateral surface 42f2 has an inclination angle of greater than 90° and less than or equal to 125° to the transverse direction.
Next described is the flow of the refrigerant of the cooling device 3 according to the second embodiment, with reference to
When introduced from the distribution pipe 44a of the cooling case 40, the refrigerant moves through the distribution pipe 44a and the inflow channel 40h1 and then flows into the inflow area 42 from the inlet 40h. That is, the refrigerant flows into the inflow area 42 as travelling parallel to the inner lateral surfaces 41a and 41c (in the +X direction, i.e., the longitudinal direction).
A part of the refrigerant then hits the diffusion surface 42d and is diffused by the diffusion surface 42d, as in the first embodiment. The diffused refrigerant spreads from the diffusion surface 42d in the −Y direction (toward the inner lateral surface 41a and the outer lateral surface 40a) as well as in the −Y and −X direction (toward the vicinity of the corner formed by the inner lateral surfaces 41a and 41b (the outer lateral surfaces 40a and 40b)). That is, the refrigerant flows through the region A of
In addition, the refrigerant having flowed into the inflow area 42 passes beyond the diffusion surface 42d and proceeds directly to the inner lateral surface 41d. The refrigerant flowing in the +X direction beyond the diffusion surface 42d moves straight inside the groove part 42f toward the inner lateral surface 41d. During this time, a part of the refrigerant flows out from the groove part 42f over the groove lateral surface 42f2 in the −Y direction toward the inner lateral surface 41a.
The refrigerant having reached the inner lateral surface 41d then flows toward the inner lateral surface 41a along the inner lateral surface 41d (in the −Y direction, i.e., the transverse direction) and eventually flows out from the outlet 40i. After the refrigerant flowing out from the groove part 42f travels toward and reaches the inner lateral surface 41a, the refrigerant then moves toward the inner lateral surface 41d along the inner lateral surface 41a and flows out from the outlet 40i.
In the cooling case 40 of the second embodiment, the refrigerant diffused by the diffusion surface 42d spreads from the diffusion surface 42d in the −Y direction (toward the inner lateral surface 41a and the outer lateral surface 40a) as well as in the −Y and −X direction (toward the vicinity of the corner formed by the inner lateral surfaces 41a and 41b (the outer lateral surfaces 40a and 40b)), as in the first embodiment. Further, the provision of the groove part 42f facilitates the refrigerant travelling through the groove part 42f to be distributed inside the flow passage area 41 from the inner lateral surface 41c toward the inner lateral surface 41a along the inner lateral surface 41d (in the transverse direction). Therefore, the cooling case 40 of the second embodiment is able to spread the refrigerant better throughout the flow passage area 41 than in the first embodiment. Thus, it is possible to further suppress variations in cooling performance depending on the position on the top surface 31 of the top plate 30 provided on the cooling case 40 and, therefore, uniform cooling performance is achieved. In this manner, the problem of reduced cooling performance is improved even more.
In Modification 2-1, a modification of the groove bottom surface 42f1 of the groove part 42f included in the aforementioned cooling device 3 is explained with reference to
As in the second embodiment, the groove bottom surface 42f1 of the groove part 42f included in the cooling case 40 of Modification 2-1 is connected to the diffusion surface 42d, extends along the inner lateral surface 41c (in the longitudinal direction), and is then connected to the inner lateral surface 41d. At this time, the groove bottom surface 42f1 is sloped upward toward the inner lateral surface 41d. That is, the groove bottom surface 42f1 is located higher on the inner lateral surface 41d side than on the diffusion surface 42d side. For example, according to
The refrigerant is also introduced into the cooling case 40 including the groove part 42f with the above configuration in the same manner as described above. The refrigerant passes through the distribution pipe 44a and the inflow channel 40h1 and then flows into the inflow area 42 from the inlet 40h. The refrigerant flows into the inflow area 42 as travelling parallel to the inner lateral surfaces 41a and 41c (in the +X direction, i.e., the longitudinal direction).
A part of the refrigerant then hits the diffusion surface 42d and is diffused by the diffusion surface 42d, as in the first embodiment. The diffused refrigerant spreads from the diffusion surface 42d in the −Y direction (toward the inner lateral surface 41a and the outer lateral surface 40a) as well as in the −Y and −X direction (toward the vicinity of the corner formed by the inner lateral surfaces 41a and 41b (the outer lateral surfaces 40a and 40b)).
In addition, the refrigerant having flowed into the inflow area 42 passes beyond the diffusion surface 42d and proceeds inside the groove part 42f toward the inner lateral surface 41d. In the groove part 42f, the refrigerant is more difficult to flow on the inner lateral surface 41d side than on the diffusion surface 42d side. In view of this, the height H2 is set to be less than the height H1 according to Modification 2-1. This configuration, therefore, facilitates the refrigerant to flow out from the entire (longitudinal direction of) groove part 42f toward the inner lateral surface 41a. Thereby, it is possible to reduce the difference in flow velocity across the flow passage area 41, i.e., the flow velocity difference among the inner lateral surface 41b side, the inner lateral surface 41d side, and the central region of the flow passage area 41. In this manner, the cooling case 40 of Modification 2-1 allows the refrigerant to spread better throughout the flow passage area 41 than in the second embodiment.
Note that, also in the inflow area 42 of the second embodiment, at least one of the diffusion surface 42d and the lateral surface 42a may be inclined, as described in Modification 1-1. In addition, the guide walls 42g may be formed in the inflow area 42 of the second embodiment, as described in Modification 1-2.
Next described is the cooling device 3 (the cooling case 40) according to a third embodiment, with reference to
The cooling case 40 of the third embodiment differs from the cooling case 40 of the second embodiment in having, on the outlet 40i side, an outflow area (outflow passage) 43 corresponding to the inflow area 42 and a groove part 43f corresponding to the groove part 42f. The outflow is 43 also included in the flow passage.
The outflow area 43 is surrounded by an outflow bottom surface 43e and lateral surfaces 43a to 43d. The outflow bottom surface 43e is recessed from the flow passage bottom surface 41e (located in the −Z direction relative to the flow passage bottom surface 41e) and has a rectangular shape in plan view. The outflow bottom surface 43e is substantially parallel to the flow passage bottom surface 41e.
The lateral surfaces 43a to 43d sequentially surround the outflow bottom surface 43e on all four sides in plan view, and connect each side of the outflow bottom surface 43e to the flow passage bottom surface 41e. Note that, according to the third embodiment, the outflow area 43 is formed, relative to the flow passage area 41, in the vicinity of the corner formed by the inner lateral surfaces 41a and 41d in plan view. Accordingly, the lateral surfaces 43a and 43d of the outflow area 43 are flush with the inner lateral surfaces 41a and 41d, respectively. Therefore, the lateral surfaces 43b and 43c connect the outflow bottom surface 43e and the flow passage bottom surface 41e. In plan view, the lateral surfaces 43a and 43c correspond to the long sides of the outflow bottom surface 43e while the lateral surfaces 43b and 43d correspond to the short sides of the outflow bottom surface 43e.
Thus, the outflow area 43 (the lateral surfaces 43a to 43d, and the outflow bottom surface 43e) correspond to the inflow area 42 (the lateral surfaces 42a to 42c and the diffusion surface 42d, and the inflow bottom surface 42e). In particular, the lateral surface 43b corresponds to the diffusion surface 42d, and the lateral surface 43c corresponds to the lateral surface 42a. Therefore, the outflow area 43 may be the same in size as the inflow area 42 described in the first embodiment. In addition, the inclination angle between the lateral surfaces 43b and 43c may be the same as that between the diffusion surface 42d and the lateral surface 42a described in the first embodiment.
In addition, the groove part 43f is formed in the flow passage area 41 in such a manner as to extend, in plan view, from the lateral surface 43b of the outflow area 43 toward the inner lateral surface 41b along the inner lateral surface 41a (in the −X direction, i.e., the longitudinal direction). The width of the groove part 43f in the ±Y direction is equal to the width of the outflow area 43 in the same direction. In addition, the groove part 43f is defined by a groove bottom surface 43f1, a groove lateral surface 43f2, and the inner lateral surfaces 41a and 41b.
The groove bottom surface 43f1 is connected to the lateral surface 43b, extends along the inner lateral surface 41a (in the longitudinal direction), and is then connected to the inner lateral surface 41b. The groove bottom surface 43f1 is located, in the ±Z direction, lower than the flow passage bottom surface 41e and higher than the outflow bottom surface 43e. In addition, the groove bottom surface 43f1 is substantially parallel to the flow passage bottom surface 41e and the outflow bottom surface 43e. The entire groove bottom surface 43f1 is flat and smooth. Note that if the depth of the groove bottom surface 43f1 from the flow passage bottom surface 41e is too sharrow, the refrigerant does not travel straight along the groove part 43f. On the other hand, if it is too deep, the refrigerant traveling straight in the groove part 43f becomes difficult to flow out to the flow passage area 41. Therefore, the depth of the groove bottom surface 43f1 from the flow passage bottom surface 41e is preferably 10% or more of the depth of the outflow bottom surface 43e from the flow passage bottom surface 41e.
The groove lateral surface 43f2 extends to the inner lateral surface 41b, running parallel to the inner lateral surface 41a (in the longitudinal direction). The groove lateral surface 43f2 connects the groove bottom surface 43f1 to the flow passage bottom surface 41e. Note that the third embodiment depicts a case where the groove lateral surface 43f2 is perpendicular to the groove bottom surface 43f1 and the flow passage bottom surface 41e; however, the groove lateral surface 43f2 may be inclined at an obtuse angle to the groove bottom surface 43f1. That is, the groove lateral surface 43f2 may be inclined at an obtuse angle to the transverse direction (the +Y direction). This prevents eddy currents from being possibly induced when the groove lateral surface 43f2 is perpendicular to the groove bottom surface 43f1. Note however that if the inclination is too large, there is a risk that the refrigerant flowing into the groove lateral surface 43f2 may fail to hit the multiple fins 33. For this reason, the inclination angle is, for example, greater than 90° and less than or equal to 125°. That is, the groove lateral surface 43f2 has an inclination angle of greater than 90° and less than or equal to 125° to the transverse direction.
As described above, the cooling case 40 of the third embodiment is configured by providing the outflow area 43 and the groove part 43f on the outlet 40i side in the cooling case 40 of the second embodiment. That is, the outflow area 43 and the groove part 43f are point symmetrical to the inflow area 42 and the groove part 42f, respectively, to thereby keep the cooling case 40 balanced. This eliminates the imbalance in the pressure for feeding the refrigerant inside the cooling case 40, which ensures the refrigerant having flowed into the flow passage area 41 of the cooling device 3 to circulate throughout the flow passage area 41 and then be discharged.
According to an aspect, it is possible to suppress reduced cooling performance without restricting the installation area of the capacitor and prevent decreased reliability of the semiconductor device.
All examples and conditional language provided herein are intended for the pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although one or more embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-132988 | Aug 2022 | JP | national |
This application is a continuation application of International Application PCT/JP2023/025669 filed on Jul. 12, 2023, which designated the U.S., which claims priority to Japanese Patent Application No. 2022-132988, filed on Aug. 24, 2022, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/025669 | Jul 2023 | WO |
| Child | 18785626 | US |
