JP2021068838A - Power module and power semiconductor device using the same - Google Patents

Abstract

To provide a power module having a heat dissipation structure allowing enough heat dissipation even when an oil coolant is used under a severe heat environment, and a power semiconductor device which uses the power module and includes an oil-cooling mechanism.SOLUTION: A power semiconductor device uses a power module. The power module comprises a semiconductor element, a first input and output terminal electrically connected to one surface of the semiconductor element, and a second input and output terminal electrically connected to the other surface of the semiconductor element. The semiconductor element, the first input and output terminal, and the second input and output terminal are sealed by an electric insulation material. A surface of the power module in contact with the coolant has a heat dissipation metal layer including a prescribed micro uneven structure. The power semiconductor device further includes a cooling channel for circulating the coolant in contact with the heat dissipation metal layer. A cooling channel wall constituting the cooling channel is composed of a dielectric transmitting an infrared ray of a wavelength longer than or equal to 1 μm and shorter than or equal to 8 μm.SELECTED DRAWING: Figure 1B

Description

The present invention relates to a semiconductor module technique, and more particularly to a power module for controlling a large amount of electric power and a power semiconductor device using the power module.

In recent years, in industrial machines and vehicles (for example, automobiles and railroad vehicles), electrification and electronic control of power sources have been rapidly progressing from the viewpoint of energy saving and precise operation control, and along with this, power sources (for example, for example) have been rapidly advanced. , A power module for power control of a rotary electric machine) and a power semiconductor device (for example, a power conversion device) using the power module are becoming very important.

Due to the demand for higher output for power sources, it is becoming necessary to increase the power of power modules that control the power of power sources. However, since increasing the power of the power module is directly linked to the increase in heat generation during operation, efficient thermal measures are taken to prevent thermal runaway of the semiconductor elements (also called power semiconductor elements) that make up the power module. (For example, heat dissipation and cooling) are required.

Until now, as a method of radiating and cooling a semiconductor element, a heat radiating member (for example, a heat sink) has been arranged in the vicinity of the semiconductor element, and the radiating member is brought into contact with a refrigerant (for example, air or water) to radiate and cool the semiconductor element. The method is common. The key points are reducing the thermal resistance from the semiconductor element to the heat radiating member and improving the heat transfer from the heat radiating member to the refrigerant.

For example, Patent Document 1 (Japanese Patent Laid-Open No. 2016-72281) includes a semiconductor element and a ceramics circuit board on which the semiconductor element is mounted, and the ceramics circuit board has one side and the other side facing each other. A ceramic substrate, a metal circuit board bonded to the one surface of the ceramic substrate and electrically connected to the semiconductor element, and a metal heat sink bonded to the other surface of the ceramic substrate are included. The thickness of the metal circuit board is larger than the thickness of the metal heat sink, and the surface area of the metal heat sink opposite to the ceramic substrate is the surface area of the metal circuit board opposite to the ceramic substrate. A semiconductor device, which is larger than the above and further includes a heat sink attached to the metal heat sink via a predetermined grease, is disclosed.

Further, in Patent Document 2 (Japanese Patent Laid-Open No. 2017-212286), a heat radiating device, a mounting frame arranged on a mounting surface on the heat radiating device, and a mounting frame are mounted based on the mounting frame to seal a semiconductor device. A power semiconductor module and a drive circuit unit mounted on the power semiconductor module via a heat insulating sheet to drive the power semiconductor module are provided, and the heat radiating device is internally a water-cooled cooler or externally air-cooled. An intelligent power module, which comprises a cooler, is disclosed.

Japanese Unexamined Patent Publication No. 2016-722281 Japanese Unexamined Patent Publication No. 2017-212286

As mentioned above, the electrification and electronic control of power sources for industrial machines and vehicles have been progressing in recent years, and the power sources are required to be miniaturized in addition to high output. As a result, there is an increasing demand for miniaturization of power modules and power semiconductor devices, and high-density mounting of semiconductor elements is being studied. Further, from the viewpoint of miniaturization of the power source mechanism as a whole, close arrangement (for example, integration) of the power source and the power semiconductor device is required.

All of these requirements lead to an increase in the volume density of heat generated during operation, so more efficient heat countermeasures than before are required. In addition, measures to ensure electrical insulation are also important for high output (that is, high power consumption) and miniaturization.

In the main body of the power source, in order to satisfy the heat countermeasures and the electric insulation property due to the demand for high output and miniaturization, it is considered to achieve both cooling and ensuring the electric insulation property by the distribution of the electric insulating oil. On the other hand, with regard to power semiconductor devices, in addition to increasing the amount of heat generated by increasing the power of the power module and mounting it at high density, it is necessary to consider heat transfer from the power source by arranging it close to the power source. The environment will be much harsher than before.

Here, as a measure against heat of the power semiconductor device, a water cooling mechanism having high heat transferability can be considered. However, the oil cooling mechanism of the power source main body and the water cooling mechanism of the power semiconductor device are installed side by side in a small size of the entire power source mechanism. It is not preferable because it goes against the conversion. Therefore, the idea of sharing the cooling of the power semiconductor device with the oil cooling mechanism of the power source body can be considered.

However, the heat transfer property to oil is reduced to 1/4 to 1/5 level compared to the heat transfer property to water. Therefore, if the oil cooling mechanism is used assuming the cooling capacity of the water cooling mechanism, heat is generated. It may be insufficient as a countermeasure. In other words, it is required to develop a heat dissipation structure that enables sufficient heat dissipation even if an oil cooling mechanism is used.

Therefore, an object of the present invention is to provide a power module having a heat dissipation structure that enables sufficient heat dissipation even when an oil refrigerant is used, and an oil cooling mechanism using the power module in order to cope with a severe thermal environment. The purpose is to provide a power semiconductor device.

One aspect of the present invention is a power module that is brought into contact with a refrigerant to be cooled.
With semiconductor elements
A first input / output terminal electrically connected to one surface of the semiconductor element,
It has a second input / output terminal that is electrically connected to the other surface of the semiconductor element.
The semiconductor element, the first input / output terminal, and the second input / output terminal are sealed with an electric insulating material.
Provided is a power module characterized by having a thermal radiation metal layer having a predetermined microconcavo-convex structure on the surface of the power module in contact with the refrigerant.
In the present invention, the micro-concavo-convex structure is defined as the case where the concavo-convex gap (height difference of the concavo-convex) is less than 100 μm (less than 0.1 mm).

(II) Another aspect of the present invention is a power semiconductor device using a power module.
The power module is the power module described above.
A cooling channel for circulating the refrigerant in contact with the thermal radiation metal layer is provided.
Provided is a power semiconductor device, characterized in that the cooling channel wall constituting the cooling channel is made of a dielectric material that transmits infrared rays having a wavelength of 1 μm or more and 8 μm or less.

According to the present invention, a power module having a heat dissipation structure that enables sufficient heat dissipation even when an oil refrigerant is used in a harsh thermal environment, and a power semiconductor using the power module and having an oil cooling mechanism. Equipment can be provided.

It is a perspective schematic diagram which shows an example of the power module which concerns on 1st Embodiment. It is sectional drawing which shows an example of the power semiconductor device using the power module of FIG. 1A. It is a perspective exploded schematic diagram which shows an example of the power module which concerns on 2nd Embodiment. It is sectional drawing which shows an example of the power semiconductor device using the power module of FIG. 2A.

The present invention can make the following improvements and changes in the power module (I) described above.
(I) The refrigerant is an electrically insulating oil.
(Ii) Further having an insulating substrate, the semiconductor element is disposed on one surface of the insulating substrate, a heat radiating layer is disposed on the other surface of the insulating substrate, and the surface region of the heat radiating layer is provided. The thermal radiation metal layer is formed.
(Iii) The first input / output terminal and the second input / output terminal are joined so as to sandwich the semiconductor element from both sides, and the surface of the first input / output terminal opposite to the surface joined to the semiconductor element. A part and a part of the surface of the second input / output terminal opposite to the surface joined to the semiconductor element are both surfaces that come into contact with the refrigerant.
(Iv) In the predetermined microconcavo-convex structure, the pitch of the concavo-convex is within the range of 0.5 μm or more and 10 μm or less, and the gap of the concavo-convex is within the range of 0.25 μm or more and 10 μm or less.
(V) A protective layer is formed on the surface of the thermal radiation metal layer, and the protective layer is made of a dielectric material that transmits infrared rays having a wavelength of 1 μm or more and 8 μm or less.

Hereinafter, embodiments according to the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to the embodiments taken up here, and can be appropriately combined with a known technique or improved based on the known technique without departing from the technical idea of the invention. .. In addition, the same reference numerals may be given to members having the same meaning, and duplicate description may be omitted.

[First Embodiment]
FIG. 1A is a schematic perspective view showing an example of a power module according to the first embodiment, and FIG. 1B is a schematic cross-sectional view showing an example of a power semiconductor device using the power module of FIG. 1A.

In FIG. 1A, the illustration of sealing with an electric insulating material is omitted so that the internal configuration of the power module can be easily understood. Further, although FIGS. 1A and 1B show a three-terminal power module, the present invention is not limited thereto, and may be, for example, a two-terminal power module.

As shown in FIG. 1A, the power module 100 is arranged on an insulating substrate 111 having a circuit layer 112 formed on one surface and a heat dissipation layer 113 formed on the other surface, and a circuit layer 112. The semiconductor element 121, the first input / output terminal 131 electrically connected to one surface of the semiconductor element 121 via the circuit layer 112, and the other surface of the semiconductor element 121 via the conductive wire 134 and the circuit layer 112. It has a second input / output terminal 132 that is electrically connected, and a gate signal terminal 133 that transmits a gate signal that controls the semiconductor element 121 via the conductive wire 134 and the circuit layer 112.

The power module 100 is a power module that cools the heat radiating layer 113 by contacting it with a refrigerant. The heat radiating layer 113 has a heat radiating metal layer 113b having a predetermined microconcavo-convex structure formed on the surface region of the heat radiating layer base material 113a. Has a structure that has been modified.

Although not shown in FIG. 1A, from the viewpoint of electrical insulation, the semiconductor element 121, the conductive wire 134, the circuit layer 112, the first input / output terminal 131, the second input / output terminal 132, and the gate signal terminal 133 are electrically insulated. It is preferably sealed with material 141 (see FIG. 1B).

Further, as shown in FIG. 1B, the power semiconductor device 150 is a power semiconductor device using the power module 100 of FIG. 1A, and includes a cooling channel 161 for circulating a refrigerant 162 in contact with the heat radiation layer 113. The cooling channel 161 preferably has a cooling channel wall 163 made of a dielectric material that transmits infrared rays having a wavelength of 1 μm or more and 8 μm or less. In the present invention, transmitting infrared rays means that a band having a wavelength of 1 μm or more and 8 μm or less includes a band having a transmittance of 50% or more.

In the power semiconductor device 150, the sealing case 142 is not an indispensable configuration, and the sealing case 142 may or may not be arranged according to the material of the electrical insulating material 141.

Next, each component of the power module 100 and the power semiconductor device 150 will be described in more detail.

The semiconductor element 121 is not particularly limited as long as it exhibits the functions required for the power module for power control, and the conventional semiconductor elements such as a rectifying diode, an IGBT (Insulated Gate Bipolar Transistor), and a power MOSFET (Power Metal Oxide) are used. Semiconductor Field Effect Transistor), MOSGTO thyristor (MOS Gate Turn-Off thyristor), etc. can be used as appropriate.

The insulating substrate 111 is not particularly limited as long as it satisfies the properties required for the power module for power control (for example, withstand voltage, relative permittivity, mechanical strength), and the conventional insulating substrate (for example, ceramic substrate, etc.) Resin substrate) can be used as appropriate. Further, the thickness of the insulating substrate 111 can be appropriately selected within the range of, for example, 0.1 mm or more and 5 mm or less.

Examples of ceramic substrates include alumina (Al ₂ O ₃ ) substrate, alumina zirconia (Al ₂ O ₃ / ZrO ₂ ) substrate, aluminum nitride (AlN) substrate, silicon nitride (SiN) substrate, and steatite (MgO-SiO _2). ) Substrates and the like. Examples of the resin substrate include a phenol resin substrate, an epoxy resin substrate, a polyimide resin substrate, a fluororesin substrate, a bismaleimide triazine resin substrate, and the like on a paper, glass cloth, or composite material as a base material.

The circuit layer 112 is also not particularly limited as long as it satisfies the properties (for example, conductivity, energization current amount, cost) required for the power module for power control, and the conventional circuit layer (for example, aluminum (Al) circuit layer). , Copper (Cu) circuit layer, Cu alloy circuit layer) can be used as appropriate. The thickness of the circuit layer 112 can be appropriately selected within the range of, for example, 0.01 mm or more and 3 mm or less. Further, from the viewpoint of bondability between the circuit layer 112 and the conductive component (for example, a semiconductor element, an input / output terminal, a gate signal terminal), a bonded metal layer (for example, a gold (Au) layer) is formed on a part of the surface of the circuit layer 11. , Silver (Ag) layer, Nickel (Ni) layer) may be plated.

The conductive wire 134 is also not particularly limited as long as it satisfies the properties required for the power module for power control (for example, conductivity, energization current amount, cost), and the conventional conductive wire (for example, Al wire, Cu wire). Can be used as appropriate.

The heat radiating layer 113 is composed of a heat radiating layer base material 113a and a thermal radiation metal layer 113b formed in a surface region thereof. It is important that the heat radiating layer base material 113a has good thermal conductivity, and a material similar to that of the circuit layer 112 (for example, Al, Cu, Cu alloy) can be preferably used. The thickness of the heat radiating layer base material 113a is not particularly limited and can be appropriately selected within the range of, for example, 0.01 to 3 mm. There is no relationship between the thickness of the heat dissipation layer base material 113a and the thickness of the circuit layer 112, and they may be different or the same.

The method of forming the circuit layer 112 and the heat radiating layer 113 on the insulating substrate 111 is not particularly limited, and the conventional method can be appropriately used. For example, it can be integrated by sticking and joining via a bonding material (solder, metal paste, etc.).

A major feature of this embodiment is that a thermal radiation metal layer 113b having a predetermined microconcavo-convex structure is formed in the surface region of the heat radiation layer base material 113a. In the micro-concavo-convex structure, the uneven pitch (in-plane pitch of the thermal radiation metal layer 113b) is within the range of 0.5 μm or more and 10 μm or less, and the uneven gap (gap in the thickness direction of the thermal radiation metal layer 113b). Is preferably in the range of 0.25 μm or more and 10 μm or less.

By controlling the microconcavo-convex structure of the thermal radiation metal layer 113b within such a range, infrared rays having a wavelength of 1 μm or more and 8 μm or less are selectively emitted from the surface of the thermal radiation metal layer 113b. This is because when a periodic microconcavo-convex structure is formed on the surface of a metal body, the surface plasmon resonates at a specific frequency and emits an electromagnetic wave of the specific frequency (that is, a specific wavelength). .. Specifically, the integrated amount of infrared radiation spectrum with a wavelength of 1 μm or more and 8 μm or less occupies a ratio of 0.4 or more with the integrated amount of infrared radiation spectrum with a wavelength of 1 μm or more and 20 μm or less.

The method for forming the thermal radiation metal layer 113b is not particularly limited, and the conventional method can be appropriately used. For example, a microconcavo-convex structure may be formed on the surface of the heat radiating layer base material 113a by a photolithography method, a microconcavo-convex structure may be formed by a vapor phase film forming method such as thin film deposition, or average grains. Metal particles having a diameter of 1 to 4 μm may be adhered to form a microconcavo-convex structure.

The emissivity and absorption rate of electromagnetic waves on the surface of a substance can be obtained by simulation by an electromagnetic field analysis method or measurement by a Fourier transform infrared spectrophotometer or the like. In addition, according to Kirchhoff's law, the emissivity and absorption rate of electromagnetic waves are equal to each other in the local thermal equilibrium state. Therefore, when the transmittance and reflectance of each wavelength when an electromagnetic wave is incident on the thermal radiation surface are measured,
Relational expression "emissivity = absorption rate = 1-transmittance-reflectivity"
The emissivity can be calculated by

Although not shown in FIGS. 1A and 1B, a protective layer may be formed on the surface of the thermal radiation metal layer 113b in order to physically protect the microconcavo-convex structure. At this time, the protective layer is preferably made of a dielectric material (for example, a resin material or a ceramic material) that transmits infrared rays having a wavelength of 1 μm or more and 8 μm or less. This is because such a dielectric can be considered transparent to the infrared rays emitted from the thermal radiation metal layer 113b.

Examples of resin materials that serve as protective layers include phenol resin, alkyd resin, aminoalkyd resin, urea resin, silicone resin, melamine urea resin, epoxy resin, polyurethane resin, unsaturated polyester resin, vinyl acetate resin, acrylic resin, and chloride. Examples include rubber-based resins, vinyl chloride resins, and fluororesins. A combination of two or more of these resin materials may be used. From the viewpoint of heat resistance, acrylic resin, unsaturated polyester resin, epoxy resin and the like are preferable.

Examples of the ceramic material serving as the protective layer include boron nitride, aluminum nitride, aluminum oxide, magnesium oxide, titanium oxide, zirconium oxide, iron oxide, copper oxide, nickel oxide, cobalt oxide, lithium oxide, silicon dioxide and the like. .. A combination of two or more of these ceramic materials may be used. Further, it may be a composite with the above resin material.

The electric insulating material 141 is not particularly limited as long as it satisfies the properties required for the power module for power control (for example, electric insulating property, withstand voltage resistance, arc discharge resistance, heat resistance), and the conventional electric insulating material is not limited. (For example, acrylic resin, unsaturated polyester resin, epoxy resin, silicone gel, electrically insulating gas) can be appropriately used. When the electrical insulating material 141 has high fluidity, it is better to dispose the sealing case 142.

As described above, since the power module and the power semiconductor device of the present invention are premised on cooling and heat dissipation by the oil cooling mechanism, it is preferable to use electrically insulating oil as the refrigerant 162. As long as it meets the properties required for use in electrical and electronic equipment (eg, electrical insulation, heat resistance, flame retardancy, oxidation resistance), there are no particular restrictions, and conventional electrical insulating oil (eg, mineral oil). , Alkibenzene, polybuden, alkylnaphthalene, alkyldiphenylalkane, ester oil, silicone oil, vegetable oil) can be appropriately used.

[Second Embodiment]
FIG. 2A is a perspective exploded schematic view showing an example of a power module according to the second embodiment, and FIG. 2B is a sectional schematic view showing an example of a power semiconductor device using the power module of FIG. 2A.

In FIG. 2A, the illustration of the sealing with the electric insulating material is omitted so that the internal configuration of the power module can be easily understood. Further, although FIGS. 2A and 2B show a three-terminal power module, the present invention is not limited thereto, and may be, for example, a two-terminal power module.

As shown in FIG. 2A, in the power module 200, the first input / output terminal 231 is electrically connected to one surface of the semiconductor element 221 via a bonding material (for example, solder or metal paste), and the second input / output terminal 231 is second input / output. The terminal 232 is electrically connected to the other surface of the semiconductor element 221 via a bonding material, and the gate signal terminal 233 is electrically connected to one surface of the semiconductor element 221 via the conductive wire 234. That is, the first input / output terminal 231 and the second input / output terminal 232 are joined so as to sandwich the semiconductor element 221 from both sides.

The power module 200 is also a power module that cools by contacting with a refrigerant, and is a part of the surface of the first input / output terminal 231 opposite to the surface joined to the semiconductor element 221 and the semiconductor element of the second input / output terminal 232. A thermal radiation metal layer 213b that comes into contact with the refrigerant is formed on a part of the surface opposite to the surface bonded to the 221. Compared with the power module 100 described above, the first input / output terminal 231 and the second input / output terminal 232 of the power module 200 can be considered to also serve as the heat dissipation layer base material 113a of the power module 100.

Although not shown in FIG. 2A, from the viewpoint of electrical insulation and mechanical stability, the semiconductor element 221, the conductive wire 234, the first input / output terminal 231, the second input / output terminal 232, and the gate signal terminal 233 are electrically connected. It is preferably sealed with insulating material 241 (see FIG. 2B).

Further, as shown in FIG. 2B, the power semiconductor device 250 is a power semiconductor device using the power module 200 of FIG. 2A, and includes a cooling channel 261 for circulating a refrigerant 262 in contact with the thermal radiation metal layer 213b. .. The cooling channel 261 is preferably made of a dielectric whose cooling channel wall 263 transmits infrared rays having a wavelength of 1 μm or more and 8 μm or less.

As the constituent members of the power module 200 and the power semiconductor device 250 of the second embodiment, the same components as those of the power module 100 and the power semiconductor device 150 of the first embodiment can be used. Further, as in the first embodiment, in order to physically protect the microconcavo-convex structure of the thermal radiation metal layer 213b, a protective layer may be formed on the surface thereof.

Hereinafter, the present invention will be described in more detail by various experiments. However, the present invention is not limited to the configurations and structures described in these experiments.

[Experiment 1]
(Manufacturing of simulated power modules of Examples 1-1 to 1-2 and Comparative Example 1)
Three types of simulated power modules were manufactured in order to test-evaluate changes in heat dissipation characteristics due to the structure of the heat dissipation layer. First, a SiN substrate (length 50 mm x width 50 mm x thickness 0.635 mm) is used as an insulating substrate, and a Cu plate (JIS C1020, length 48 mm x width 48 mm x thickness 1.3 mm) is used as a circuit layer on one surface. ) Was pasted, and a Cu plate (JIS C1020, length 48 mm x width 48 mm x thickness 1.0 mm) was pasted on the other surface as a heat dissipation layer.

Next, for a simulated power module that imitates the first embodiment (see FIGS. 1A and 1B), a microconcavo-convex structure (cylindrical recess: diameter 2 μm) is applied to the surface region of the Cu plate of the heat dissipation layer by a photolithography method. A thermal radiation metal layer having a depth of 2 μm and an in-plane pitch of columnar recesses of 4.2 μm) was formed. Further, for another simulated power module that imitates the first embodiment, Cu powder (average particle size 2 μm) is adhered and bonded to the surface region of the Cu plate of the heat radiation layer to have a particle-like microconcavo-convex structure. A metal layer was formed. On the other hand, for the simulated power module of the comparative example, a module that does not form a microconcavo-convex structure in the surface region of the heat radiation layer (has no thermal radiation metal layer) was also prepared.

The infrared radiation amount of the heat radiation layer having the microconcavo-convex structure and the infrared radiation amount of the heat radiation layer not forming the microconcavo-convex structure were measured by a Fourier transform infrared spectrophotometer. As a result, the integral amount of the infrared emission spectrum of infrared rays having a wavelength of 1 to 8 μm in the heat radiating layer having the microconcave structure of the columnar recess was 0.6 or more with respect to the integral amount of the infrared emission spectrum of infrared rays having a wavelength of 1 to 20 μm. The integral amount of the infrared emission spectrum of infrared rays having a wavelength of 1 to 8 μm in the heat radiating layer having a particulate microconcave structure was 0.5 or more with respect to the integral amount of the infrared emission spectrum of infrared rays having a wavelength of 1 to 20 μm. On the other hand, the integral amount of the infrared emission spectrum of infrared rays having a wavelength of 1 to 8 μm in the heat radiating layer not forming the microconcavo-convex structure was about 0.2 with respect to the integral amount of the infrared emission spectrum of infrared rays having a wavelength of 1 to 20 μm.

As a substitute for the semiconductor element that is the heat generation source, Cu plates (JIS C1020, length 12 mm x width 12 mm x thickness) on both sides of a commercially available polyimide film heater (length 12 mm x width 12 mm x thickness 0.2 mm) A simulated semiconductor device with a 1 mm) attached was prepared.

Next, the prepared simulated semiconductor element was solder-bonded onto the Cu plate of the circuit layer, and then the simulated semiconductor element and the circuit layer were coated and sealed with a commercially available silicone gel (the heat dissipation layer was exposed). As a result, Example 1-1 has a micro-concavo-convex structure of columnar recesses on the surface of the heat-dissipating layer, Example 1-2 has a micro-concave structure of particles on the surface of the heat-dissipating layer, and the surface of the heat-dissipating layer has a micro-concave structure. A simulated power module of Comparative Example 1 was produced.

(Manufacture of simulated power semiconductor device of Examples 1-1 to 1-2 and Comparative Example 1 and heat dissipation characteristic test)
Fill a resin container (corresponding to the cooling channel wall) with commercially available ester-based electrical insulating oil (corresponding to the refrigerant) to prepare a cooling channel, and immerse the heat dissipation layer of the simulated power module prepared above in the refrigerant. Arranged to produce simulated power semiconductor devices of Examples 1-1 to 1-2 and Comparative Example 1.

When the infrared transmittances of the resin container and the ester-based electrical insulating oil used were separately measured, the infrared transmittances of infrared rays having a wavelength of 1 to 8 μm were 90% or more. That is, the resin container and ester-based electrically insulating oil used can be regarded as being substantially transparent to the infrared rays.

Next, a heat dissipation characteristic test of a simulated power semiconductor device was performed. The refrigerant was circulated while adjusting the temperature so that the temperature of the refrigerant was 60 ± 1 ° C, and the input power P (unit: W) was measured while adjusting the temperature of the simulated semiconductor element to 150 ± 1 ° C. The simulated power semiconductor device was installed so that the heat dissipation layer of the simulated power module faces the top plate surface of the desk in a room temperature environment.

Heat dissipation characteristics of the simulated power semiconductor device, the effective heat transfer property h _e ^{(Unit: W / (m 2 · K} )) from the simulated power module to the installation environment and can be considered. That is, the input power P (unit: W) to the simulated semiconductor element, the temperature T _s (150 ° C = 423 _{K) of the simulated semiconductor element, the temperature T c} (60 ° C = 333 K) of the refrigerant, and the area A of the simulated semiconductor element. From (12 mm x 12 mm = 1.44 x 10 ^-4 m ² )
Relational expression "h _e = P / A (T _{s −} T _c )"
Can be obtained by.

Based on the heat dissipation characteristics of the simulated power semiconductor device of Comparative Example 1 (no micro-concavo-convex structure on the surface of the heat-dissipating layer), the simulated power semiconductor device of Example 1-1 (having a micro-concavo-convex structure of cylindrical recesses on the surface of the heat-dissipating layer) and The ratio of heat dissipation characteristics in the simulated power semiconductor device of Example 1-2 (having a particle-like microconcavo-convex structure on the surface of the heat dissipation layer) was determined. The results are shown in Table 1. As is clear from Table 1, it was confirmed that the simulated power semiconductor devices of Example 1-1 and Example 1-2 exhibit heat dissipation characteristics of about 2.4 times and about 2.1 times that of Comparative Example 1, respectively. It was.

[Experiment 2]
(Manufacturing and energization test of power semiconductor devices of Example 2 and Comparative Example 2)
A power semiconductor device (see FIG. 1B) according to the first embodiment was manufactured. First, an AlN substrate (length 50 mm x width 50 mm x thickness 0.635 mm) is used as an insulating substrate, and a Cu plate (JIS C1020, length 48 mm x width 48 mm x thickness 0.3 mm) is used as a circuit layer on one surface. ) Was pasted, and a Cu plate (JIS C1020, length 48 mm x width 48 mm x thickness 0.2 mm) was pasted on the other surface as a heat dissipation layer.

Next, for the power module of Example 2, the surface region of the Cu plate of the heat dissipation layer has a microconcavo-convex structure (cylindrical recess: diameter 2 μm × depth 2 μm, in-plane pitch of the columnar recess) as in Experiment 1. A thermal radiation metal layer having 4.2 μm) was formed. On the other hand, for the power module of Comparative Example 2, a module that does not form a microconcavo-convex structure in the surface region of the heat radiation layer (has no thermal radiation metal layer) was also prepared.

IGBTs and diode elements were prepared as semiconductor elements, and they were bonded onto the circuit layer using a sintered Cu bonding paste. An Al wire (JIS A1050, diameter 0.3 mm) was prepared as the conductive wire, and the semiconductor element, the conductive wire, and the circuit layer were bonded by an ultrasonic bonding method. Then, the semiconductor element, the circuit layer, and the conductive wire were coated and sealed with a commercially available silicone gel (the heat radiation layer was exposed). As a result, the power modules of Example 2 and Comparative Example 2 were produced.

Next, in the same manner as in Experiment 1, power semiconductor devices of Example 2 and Comparative Example 2 were produced in combination with a cooling channel.

In the power semiconductor devices of Example 2 and Comparative Example 2 produced, the refrigerant was circulated while adjusting the temperature so that the temperature of the refrigerant was 60 ± 1 ° C as in Experiment 1, and the temperature of the IGBT was 150 ± 1. The input current amount was measured while adjusting the temperature to ℃. As a result, it was confirmed that the power semiconductor device of Example 2 can input a current amount about 1.5 times that of that of Comparative Example 2. It is considered that this is because the heat dissipation characteristic of the power semiconductor device of Example 2 is higher than that of Comparative Example 2.

[Experiment 3]
(Manufacturing of Power Semiconductor Device of Example 3 and Energization Test)
First, the same circuit layer / insulating substrate / heat dissipation layer laminated substrate as in Example 2 was prepared. Next, for the power module of Example 3, a microconcavo-convex structure (cylindrical recess: diameter 1.5 μm × depth 1.5 μm, in-plane pitch of the columnar recess 3 μm) is formed in the surface region of the Cu plate of the heat dissipation layer. A thermal radiation metal layer having was formed.

The amount of infrared radiation of the heat radiating layer having the above-mentioned microconcavo-convex structure was measured by a Fourier transform infrared spectrophotometer. As a result, the integrated amount of infrared radiation spectrum with a wavelength of 1 to 8 μm was 0.4 or more with respect to the integrated amount of infrared radiation with a wavelength of 1 to 20 μm.

Next, in the same manner as in Example 2, the IGBT and the diode element were bonded onto the circuit layer using a sintered Cu bonding paste. The semiconductor element, the conductive wire, and the circuit layer were joined by an ultrasonic joining method. After that, the semiconductor element, the circuit layer, and the conductive wire are coated and sealed with a commercially available silicone gel (the heat radiation layer is exposed), and the surface thereof is used to physically protect the microconcavo-convex structure of the thermal radiation metal layer. A protective layer of acrylic resin (thickness 50 μm) was formed on the top. As a result, the power module of Example 3 was produced.

The same energization test as in Experiment 2 was performed on the produced power semiconductor device of Example 3. As a result, it was confirmed that the power semiconductor device of Example 3 can input a current amount equivalent to that of Example 2 (that is, a current amount about 1.5 times that of Comparative Example 2). This means that the protective layer formed on the microconcavo-convex structure of the thermal radiation metal layer does not adversely affect the heat dissipation characteristics.

[Experiment 4]
(Manufacturing and energization test of power semiconductor devices of Example 4 and Comparative Example 4)
A power module and a power semiconductor device (see FIGS. 2A and 2B) according to the second embodiment were manufactured. An IGBT and a diode element are prepared as semiconductor elements, and a Cu plate (JIS C1020, length 80 mm x width 40 mm (longest part) x thickness 1 mm (thinnest part)) is prepared as the first input / output terminal and the second input / output terminal. ~ 1.5 mm (thickest part)) is prepared, a Cu plate (JIS C1020, length 35 mm x width 5 mm x thickness 0.5 mm) is prepared as a gate signal terminal, and an Al wire (JIS A1050, diameter) is prepared as a conductive wire. 0.3 mm) was prepared.

For the power module of the fourth embodiment, in the outer surface region of the Cu plate of the first input / output terminal and the second input / output terminal (opposite the surface of the first input / output terminal and the second input / output terminal to be joined to the semiconductor element). In the surface region of the side surface), a thermal radiation metal layer having a microconcavo-convex structure (cylindrical recess: diameter 1.5 μm × depth 1.5 μm, columnar recess in-plane pitch 3 μm) was formed as in Experiment 3. .. On the other hand, for the power module of Comparative Example 4, a module that does not form a microconcavo-convex structure (does not have a thermal radiation metal layer) is also prepared in the outer surface region of the first input / output terminal and the second input / output terminal.

When the semiconductor element is sandwiched between the first input / output terminal and the second input / output terminal so as to be sandwiched from both sides, the surface of the first input / output terminal on which the thermal radiation metal layer is not formed is bonded to the semiconductor element, and the first 2. The surface of the input / output terminal on which the thermal radiation metal layer was not formed was bonded to the semiconductor element using a sintered Cu bonding paste. The semiconductor element, the conductive wire, and the gate signal terminal were joined by an ultrasonic joining method.

Then, the first input / output terminal, the semiconductor element, the conductive wire, the gate signal terminal, and the second input / output terminal were sealed with an epoxy resin by a transfer molding method. At this time, the Cu plate was exposed on the surface of the first input / output terminal and the second input / output terminal on the side opposite to the surface joined to the semiconductor element without resin sealing. As a result, the power modules of Example 4 and Comparative Example 4 were produced.

Next, a commercially available ester-based electric insulating oil is filled in a resin container (corresponding to the cooling channel wall) to prepare a cooling channel, and the power module prepared above is arranged so as to be immersed in the electric insulating oil. The simulated power semiconductor devices of Example 4 and Comparative Example 4 were produced.

The refrigerant was circulated in the produced power semiconductor devices of Example 2 and Comparative Example 2 while adjusting the temperature so that the temperature of the electrically insulating oil was 60 ± 1 ° C. as in Experiment 1, and the temperature of the IGBT was 150. The input current amount was measured while adjusting the temperature to ± 1 ° C. As a result, it was confirmed that the power semiconductor device of Example 4 can input a current amount about 1.4 times that of that of Comparative Example 4. It is considered that this is because the heat dissipation characteristic of the power semiconductor device of Example 4 is higher than that of Comparative Example 4.

The above-described embodiments and experimental examples have been described for the purpose of assisting the understanding of the present invention, and the present invention is not limited to the specific configurations described. For example, it is possible to replace a part of the configuration of the embodiment with the configuration of common general technical knowledge of those skilled in the art, and it is also possible to add the configuration of common general technical knowledge of those skilled in the art to the configuration of the embodiment. That is, the present invention may delete, replace with another configuration, or add another configuration to a part of the configurations of the embodiments and experimental examples of the present specification without departing from the technical idea of the invention. It is possible.

100 ... Power module,
111 ... Insulation board, 112 ... Circuit layer,
113 ... Heat dissipation layer, 113a ... Heat dissipation layer base material, 113b ... Thermal radiation metal layer, 121 ... Semiconductor element,
131 ... 1st input / output terminal, 132 ... 2nd input / output terminal, 133 ... gate signal terminal,
134 ... Conductive wire, 141 ... Electrical insulation, 142 ... Sealing case,
150 ... Power semiconductor devices,
161 ... Cooling channel, 162 ... Refrigerant, 163 ... Cooling channel wall,
200 ... Power module,
213b ... Thermal radiation metal layer, 221 ... Semiconductor element,
231 ... 1st input / output terminal, 232 ... 2nd input / output terminal, 233 ... gate signal terminal,
234 ... Conductive wire, 241 ... Electrical insulation,
250 ... Power semiconductor devices,
261 ... Cooling channel, 262 ... Refrigerant, 263 ... Cooling channel wall.

Claims (7)

A power module that cools by contacting with a refrigerant.
With semiconductor elements
A first input / output terminal electrically connected to one surface of the semiconductor element,
It has a second input / output terminal that is electrically connected to the other surface of the semiconductor element.
The semiconductor element, the first input / output terminal, and the second input / output terminal are sealed with an electric insulating material.
A power module characterized by having a thermal radiation metal layer having a predetermined microconcavo-convex structure on the surface of the power module in contact with the refrigerant. In the power module according to claim 1,
A power module characterized in that the refrigerant is an electrically insulating oil. In the power module according to claim 1 or 2.
It also has an insulating substrate,
The semiconductor element is arranged on one surface of the insulating substrate, and the semiconductor element is arranged.
A heat dissipation layer is provided on the other surface of the insulating substrate.
A power module characterized in that the thermal radiation metal layer is formed in a surface region of the heat radiation layer. In the power module according to claim 1 or 2.
The first input / output terminal and the second input / output terminal are joined so as to sandwich the semiconductor element from both sides.
A part of the surface of the first input / output terminal opposite to the surface bonded to the semiconductor element and a part of the surface of the second input / output terminal opposite to the surface bonded to the semiconductor element are both described above. A power module characterized by having a surface that comes into contact with a refrigerant. In the power module according to any one of claims 1 to 4.
The predetermined microconcavo-convex structure is a power module characterized in that the pitch of the concavo-convex is within a range of 0.5 μm or more and 10 μm or less, and the gap of the concavo-convex is within a range of 0.25 μm or more and 10 μm or less. In the power module according to any one of claims 1 to 5.
A protective layer is formed on the surface of the thermal radiation metal layer,
A power module characterized in that the protective layer is made of a dielectric material that transmits infrared rays having a wavelength of 1 μm or more and 8 μm or less. A power semiconductor device that uses a power module.
The power module is the power module according to any one of claims 1 to 6.
A cooling channel for circulating the refrigerant in contact with the thermal radiation metal layer is provided.
A power semiconductor device characterized in that the cooling channel wall constituting the cooling channel is made of a dielectric material that transmits infrared rays having a wavelength of 1 μm or more and 8 μm or less.

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