JP2001053207A - Cooling device for module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device for a module with a high heat radiation effect with no increase in manufacturing processes. SOLUTION: A circuit board 5 on which a plurality of semiconductor chips 1 are mounted contacts a cooling fluid so that the semiconductor chip 1 is directly cooled, Here, on a conductor pattern 3 arranged on the circuit board 5, a plurality of column-like wire fins 22 are provided by a wire bonding device. The heat accumulated at the semiconductor chip 1 is conducted to the conductor pattern 3 through the solder on the lower surface of chip and a power supply wire 20 arranged on the upper surface of chip, and disperses in the conductor pattern 3 before dissipated to the cooling fluid by the wire fin 22 arranged on the conductor pattern 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a circuit board and a plurality of semiconductor chips mounted on the circuit board, and a cooling fluid is brought into contact with the circuit board surface and the semiconductor chip surface by cooling fluid supply means. The present invention relates to a cooling device for a module which is made to flow and cool the semiconductor chip.

[0002]

2. Description of the Related Art In a module including a plurality of semiconductor chips and other electronic components, a circuit board, and connector terminals for input and output of power and electric signals, each component is mounted at a high density. Heat generation density is large,
There is a need for a cooling device having a higher cooling effect.

FIG. 10 is a perspective view showing an example of a conventional module. Module 00 has a plurality of semiconductor chips 1
Connector terminals 23a, 2 for inputting and outputting power and electric signals
The circuit board 5 on which 3b is mounted is sealed with a resin package 10. A radiation fin 102 is attached to the lower surface of the module 00 to release the heat of the module.

FIG. 11 is a schematic sectional view of the module 00 shown in FIG. The heat generated in the semiconductor chip 1 is conducted to the conductor pattern 3 disposed on the circuit board 5 through the solder layer 2 under the chip 1 according to the heat flow 36a. Further, the heat is transmitted to the conductor pattern 3 via the power supply wire 20 according to the heat flow 36b. The heat conducted to the conductor pattern 3 is conducted and diffused in the conductor pattern 3 as in a heat flow 36d, is conducted through the substrate 4 and the metal plate 6 in accordance with the heat flow 36e, and is released by the radiation fins 102. Further, part of the heat is conducted from the chip 1 and the conductor pattern in the sealing resin 10 as a heat flow 36g, and is released from the surface of the package 10 as a heat flow 36h.

In the module cooling device, a heat radiating means for transmitting heat generated in the chip 1 to the circuit board 5 and radiating the heat by the radiating fins 102 is used. Resistance increases.

On the other hand, as a conventional technique for removing heat from a semiconductor chip without having a heat dissipation path by conduction, there is a direct cooling method in which an insulating cooling fluid is brought into direct contact with the semiconductor chip to radiate heat from the chip surface.

FIG. 12 is a schematic sectional view showing an example of a conventional module using the direct cooling method. Module 00 has a module case upper part 11a and a lower part 11b,
The circuit board 5 is mounted on the lower case part 11b. A plurality of semiconductor chips 1 are mounted on the circuit board 5, and these circuit boards 5 and the semiconductor chips 1 are supplied through a coolant inlet 12 and a coolant outlet 13 provided in the case 11 a. Contacting coolant.

The heat generated in the semiconductor chip 1 is released from the surface of the chip 1 as a heat flow 36c by the flow 30 of the cooling liquid. The remaining heat is transferred to the heat flow 36 through the solder layer 2.
a) Conduction is conducted to the conductor pattern 3 disposed on the circuit board 5 according to the heat flow 36b via the power supply wire 20.
The heat conducted to the conductor pattern 3 is conducted and diffused in the conductor pattern 3 as a heat flow 36d, and is released from the surface of the conductor pattern 3 by the coolant flow 30 as a heat flow 36f.

Further, the chip 1 indicated by the heat flow 36c
As shown in FIG. 13, there is a means for disposing a rectangular fin 28 or a pin fin 29 on the upper surface of the chip 1 to increase the amount of heat radiation from the surface to the cooling liquid. As the pin fin 29, a wire-like member is used.
There is also a method of forming a fin without using a special member, such as arranging a bonding wire using a wire bonding apparatus as a pin fin as shown in JP-A-76654.

[0010]

In the conventional module cooling device using the direct cooling method as shown in FIG. 12, since the area in contact with the cooling liquid is only the semiconductor chip surface and the circuit board upper surface, the heat radiation area is small. There's a problem.

To solve the above problem, as a means for increasing the surface area of the semiconductor chip, there is a method of mounting a radiating fin on the chip as shown in FIG. 13, but by mounting the radiating fin, the height of the fin is reduced by the height of the fin. It is necessary to increase the height, which is against the miniaturization of the module. Further, when a special component called a radiation fin is used, there is a problem that the number of components increases and the number of manufacturing steps increases.

On the other hand, since the area of the conductor pattern on the circuit board is small, the heat resistance from the conductor pattern to the cooling liquid is large. This means that the amount of heat released from the chip to the coolant through the conductor pattern is small, that is, in the conventional module, the heat generated by the chip is not diffused to the circuit board, and most of the heat is only on the chip surface. This means that the heat is dissipated. Considering the circuit board shown in FIG. 14, the cooling liquid 30a passing over the chip 1 receives a large amount of heat, the cooling liquid 30b not passing over the chip 1 receives a small amount of heat, and the cooling efficiency of the cooling liquid is low. Not good.

Accordingly, an object of the present invention is to increase the heat radiation area without increasing the number of manufacturing steps, and to enhance the diffusivity of chip heat to a circuit board, and to efficiently dissipate heat to a cooling liquid for a module. It is to provide a device.

[0014]

In order to solve the above-mentioned problems, a cooling device for a module according to the present invention has a plurality of columnar bonding wires fixed to an upper surface portion of a conductor pattern arranged on a circuit board. Things.

Further, in the cooling device for a module according to the present invention, in the above device, the number, shape, arrangement and shape of the bonding wires may be changed according to the heat generation distribution of the module.
At least one of the height and the angle with respect to the conductor pattern is adjusted and fixed.

The cooling device for a module according to the present invention may further comprise a plurality of terminal members which are electrically connected to the conductor patterns provided on the circuit board and which are separate from the terminal members for supplying power or the like to the semiconductor chip. It is fixed to the upper surface of the conductor pattern arranged above.

Still further, in the cooling device for a module according to the present invention, in the above device, the plurality of terminal members may be plate-shaped, and the plate-shaped terminal members may be cooled by passing through the semiconductor chip located on the upstream side. The fluid is arranged so as to flow avoiding the semiconductor chip located on the downstream side.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Embodiment 1 of the present invention will be described below in detail with reference to FIGS. FIG. 1 is an external view of an electronic apparatus 100 having a power module using the present invention. 2 and 3 show the electronic apparatus 100 shown in FIG.
AA ′ and BB ′ cross-sectional view of FIG. 2 and 3, an electronic apparatus 100 includes a housing 101, a main circuit board 40, a control board 41, and a power module 0 in the housing 101.
The control circuit board 41 controls the power module 00, and the main circuit board 40 supplies power to the power module 00.

FIG. 4 is an exploded perspective view of the power module 00, and FIG. 5 is a sectional view of the power module 00. Al ₂ O ₃ on the circuit board 5 which arranged Cu conductor pattern 3 on the ceramic plate 4, such as a plurality of power semiconductor chip 1 is mounted such IGBT, the semiconductor chip 1 and on the conductor pattern 3 Are electrically connected to each other by a wire wire 20 for power supply by a wire bonding apparatus. Further, connector terminals 23a and 23b for supplying power to the module 00 and inputting / outputting signals to / from the module 00 are mounted on the circuit board 5. The circuit board 5 on which the semiconductor chip 1 and the connector terminals 23a and 23b are mounted is mounted on a module case lower part 11b. Coolant inlet 12 and coolant outlet 13
The upper portion 11a and the lower portion 11b of the module case are connected to each other.
And a lower part of the case 11b. The electrically insulating cooling liquid is supplied from the inflow port 12 to the outflow port 13 as in a liquid flow 30, and the semiconductor chip 1, the connector terminals 23a and 23b, and the circuit board 5 are supplied.
Is in contact with the cooling liquid.

A large number of columnar wire fins 22 are arranged on the conductor pattern 3 in a line at regular intervals in accordance with the pattern path of the conductor pattern 3. All of them have the same height and are arranged perpendicular to the conductor pattern 3. The wire fin 22 is formed by fixing one end to the upper surface of the conductor pattern by a wire bonding apparatus. Therefore, the attachment of the wire fins 22 can be performed in the same manufacturing process as the wire bonding mounting of the semiconductor chip 1, and the work efficiency is good.

It should be noted that in FIG.
2 are arranged in one row and at regular intervals according to the pattern path of the conductor pattern 3, but may be arranged in a plurality of rows according to the pattern path.
For example, a fin arrangement such as a staggered arrangement may be used. Further, the wire fins 22 need not be arranged at regular intervals, for example, by densely arranging the wire fins 22 in a portion near the semiconductor chip 1 where the temperature rise is large.

Referring to FIG.
Are all equal in height, but for example, the wire fins 22 are increased in a portion where the temperature rise is large near the semiconductor chip 1, and the wire fins 22 are decreased as the distance from the chip 1 is increased. May not be constant.

Referring to FIG.
Are arranged perpendicular to the conductor pattern 3, but need not be arranged perpendicular to the conductor pattern 3, for example, may be arranged to be inclined in the direction of the coolant flow 30. For example, the shape of the wire fins 22 may be curved instead of straight, such as by bending the wire fins 22 in the direction of the coolant flow 30.

As described above, when a large number of wire fins 22 are provided on the conductor pattern 3, the heat conducted to the conductor pattern 3 is released from the surface of the wire fin 22 to the coolant through the wire fin 22. That is, since the heat radiation area to the cooling liquid is increased by the surface integral of the wire fins 22, heat can be easily transmitted to the cooling liquid, and the conductor pattern 3 including the wire fins 22 as shown in FIG. 36f increases. For example, 10mm x 10mm
When wire fins with a diameter of 100 μm and a height of 3 mm were arranged in a 10 × 10 square grid with a center-to-center distance of 1 mm on a square conductor pattern, the wire fins were included for the surface area of only the conductor pattern of 100 mm ² . The surface area is about 194.2 mm ^{2, which} is about twice the surface area.

The wire fins 22 also provide a coolant flow 30
Easily generate turbulence in the Generally, on the surface of an object in contact with a fluid flow, when the flow is in a turbulent flow region, heat transfer from the object surface to the fluid is promoted more than in a laminar flow region, and more heat is released. For this reason, by disposing the wire fins 22, the heat radiation capability is further improved.

The cooling effect according to the first embodiment is as follows. That is, in a cooling device as shown in FIG. 6, (a 6 mm × 6 mm × 0.5 mm semiconductor chip 1 is placed in a rectangular tubular case 201 having an inner cross section of 10 mm × 1.8 mm).
10mm × 10 mounted via 0.12mm thick solder layer 2
A device in which a copper pattern 3 of mm × 0.3 mm is built in and a cooling water 30 of 2.7 × 10 −5 m 3 / s is supplied in the case 201), a 0.3 mm diameter and a height of 1 mm on the copper pattern 3 Chip 1-cooling water 3 in a case where Al wire fins are arranged in a staggered arrangement of 20 rows x 20 rows and in a case where the wire fins are not arranged
The thermal resistance between 0 was compared.

[0027]

[Table 1]

For comparison, as shown in the thermal model (FIG. 7), a heat radiation path is a path from the surface of the chip 1 to the cooling water 30 (thermal resistance Rc), and a solder layer 2 and a copper A path from the surface of the copper pattern 3 including the surface of the wire fin 22 to the cooling water 30 via the pattern 3
(Thermal resistance Ra + Rd + Rf), and the heat transfer coefficient necessary for calculating the thermal resistance Rc and the thermal resistance Rf when the wire fins 22 are not provided is determined by Colburn's turbulent heat transfer equation in a pipe (edited by the Japan Society of Mechanical Engineers). Heat Transfer Engineering Data ”(Revised, 4th edition, page 56), the thermal resistance R when the wire fins 22 are provided
The heat transfer coefficient required for the calculation of f is based on the heat transfer equation of the Zukauskas tube group (6th edition of the 4th edition of “Thermal Heat Transfer Data” edited by the Japan Society of Mechanical Engineers).
(See page 4). Then, the heat resistance (Rc, Rf) was calculated by substituting the heat transfer coefficient obtained by this equation into the equation of the thermal resistance due to convective heat transfer. Also, the thermal resistance R
a is given by the equation of the thermal resistance of the heat conduction of the flat plate,
Was determined by the equation of thermal resistance of heat conduction in the radial direction of the cylinder. The calculation results are as follows. (Calculation result) [K / W]

As a result, the reciprocal ratio 1 / Rc: 1 / (Ra + Rd + Rf) of the thermal resistance in each heat radiation path is 1 / 1.53 when the wire fin is not provided and when it is provided. [K /
W]: 1 / 2.26 [K / W] = 60:40, 1 / 1.53 [K / W]: 1 / 0.8
Since 4 [K / W] = 35: 65, the ratio of the heat diffused to the copper pattern out of the heat generated in the chip by providing the wire fins is improved from 40% to 65%. I understand. In addition, the total thermal resistance is 0.54% less by installing wire fins than by installing no wire fins.
Since [K / W] /0.91 [K / W] = 0.59, the chip temperature rise is also reduced to about 60%.

Second Embodiment Next, a second embodiment will be described with reference to FIGS. FIG. 8 is a perspective view of the circuit board 5 in the power module 00 according to the second embodiment. A plurality of semiconductor chips 1 and a module 00 are placed on the conductor pattern 3 arranged on the circuit board.
Connector terminal 2 for power supply and signal input / output
3a, 23b and a large number of other terminal members 24 are provided. The terminal member 24 uses the same member as the connector terminal 23a or 23b, and is attached in the same manufacturing process as the connector terminal 23a or 23b in consideration of work efficiency.

In FIG. 8, the terminal member 24 and the connector terminals 23a and 23b are rectangular plate-like members.
For example, a member such as a pin may be used and does not depend on the shape.

In FIG. 8, the terminal members 24 are all arranged in a direction in which the connector terminals 23b are translated along the surface of the circuit board 5, but may be arranged in any direction. Also, the directions of all the terminal members 24 need not be the same.

In FIG. 8, the terminal member 24 is electrically connected only to the conductor pattern 3 and does not have the function of a connector terminal.
Like 3a and 23b, it may be used as a connector terminal for inputting and outputting electric power and electric signals.

By arranging the terminal members 24 on the conductor pattern 3 as described above, the contact area with the coolant can be increased as in the operation of the wire fin in the first embodiment, and The generated heat can be easily transmitted to the cooling liquid.

As shown in the plan view of the circuit board in FIG. 9, the terminal surface 24 of the rectangular plate-like terminal member 24 is arranged not to be parallel to the coolant flow 30 but at an angle to a certain extent, so that the cooling liquid can be cooled. The flow can be rectified by changing the direction of the liquid flow 30 or dividing the flow. As shown in FIG. 9, by utilizing this rectifying action, if the coolant that has once passed over the chip and has been heated is rectified by disposing the terminal member 24 so as not to pass through again on another chip, the efficiency can be further improved. Cooling is possible. It goes without saying that the first embodiment and the second embodiment can be combined.

[0036]

As described above, according to the present invention, since the radiating fins composed of the bonding wires and the terminal members are provided on the upper surface of the conductor pattern on the circuit board, heat is easily transmitted from the conductor pattern to the cooling fluid. This allows the heat generated by the chip to be better diffused to the circuit board. By uniformly radiating the generated heat on the circuit board surface as described above, the cooling with the cooling fluid can be efficiently performed.

Further, since the heat radiation fins are not disposed on the semiconductor chip but are disposed on the conductor pattern located at the lowest position on the circuit board, the circuit of the heat radiation fins is equivalent to the height of the semiconductor chip. The height from the substrate is kept small, and the heat radiation effect can be enhanced without increasing the module height.

Further, since the heat radiation fins are bonding wires and terminal members which are members used for mounting module components, the present invention provides a module cooling device having a high heat radiation capability easily without increasing the number of manufacturing steps. Can be provided.

Further, according to the present invention, the plurality of terminal members are formed in a plate shape, and the cooling fluid passing through the semiconductor chip flows through the plate-shaped terminal members avoiding the semiconductor chip located on the downstream side. With such a configuration, it is possible to provide a module cooling device having a higher heat radiation capability.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an electronic apparatus having a cooling device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional AA ′ view of the electronic apparatus shown in FIG. 1;

FIG. 3 is a sectional view taken along line BB ′ of the electronic apparatus shown in FIG. 1;

FIG. 4 is an exploded perspective view of the power module according to the first embodiment of the present invention.

5 is a schematic sectional view of the power module shown in FIG.

FIG. 6 is a diagram for explaining a cooling effect according to the first embodiment of the present invention.

FIG. 7 is a diagram for explaining a cooling effect according to the first embodiment of the present invention.

FIG. 8 is a perspective view of a circuit board according to Embodiment 2 of the present invention.

FIG. 9 is a plan view showing a flow of a coolant in the circuit board shown in FIG. 8;

FIG. 10 is a developed perspective view showing a first example of a conventional module.

11 is a schematic sectional view of the module shown in FIG.

FIG. 12 is a schematic sectional view showing a second example of a conventional module.

FIG. 13 is a schematic sectional view showing a third example of a conventional module.

FIG. 14 is a schematic perspective view showing a coolant flow in the module shown in FIGS. 12 and 13.

DESCRIPTION OF SYMBOLS 00 Module 1 Semiconductor chip 3 Conductor pattern 5 Circuit board 12 Coolant inlet 13 Coolant outlet 22 Heat dissipating wire fins 23a, 23b Connector terminal 24 Heat dissipating terminal member 30 Coolant flow 36a, 36b, 36c, 36d, 36e, 36f Heat flow 40 Main circuit board 41 Control board 100 Electronic equipment 101 Housing

Claims (4)

[Claims] 1. A semiconductor device comprising: a circuit board; and a plurality of semiconductor chips mounted on the circuit board, wherein a cooling fluid is brought into contact with and flows on the circuit board surface and the semiconductor chip surface by cooling fluid supply means. A cooling device for a module, wherein a plurality of columnar bonding wires are fixed to an upper surface of a conductor pattern arranged on the circuit board. 2. The bonding wire according to claim 1, wherein at least one of the number, shape, arrangement, height and angle with respect to the conductor pattern is adjusted and fixed in accordance with the heat distribution of the module. 2. The cooling device for a module according to 1. 3. The semiconductor chip, comprising: a circuit board; and a plurality of semiconductor chips mounted on the circuit board, wherein a cooling fluid is brought into contact with and flows on the circuit board surface and the semiconductor chip surface by cooling fluid supply means. In a cooling device for a module that cools, a plurality of terminal members that are electrically connected to a conductor pattern disposed on the circuit board and are separate from terminal members that supply power or the like to the semiconductor chip,
A cooling device for a module, wherein the cooling device is fixed to an upper surface of a conductor pattern disposed on the circuit board. 4. The plurality of terminal members have a plate-like shape, and the plate-like terminal members allow the cooling fluid passing through the semiconductor chip located on the upstream side to flow while avoiding the semiconductor chip located on the downstream side. 4. The cooling device for a module according to claim 3, wherein the cooling device is arranged as follows.