JP2020155699A - Manufacturing method for package and power semiconductor module - Google Patents

Abstract

To provide a package capable of quickly completing a power semiconductor module after mounting a power semiconductor element while using a heat sink plate having high thermal conductivity.SOLUTION: A package 100 according to an embodiment is used to form a sealing space 950 that seals a power semiconductor element 200 without gloss leak due to attachment of a lid 300, and includes an external terminal electrode 90, a frame 80, a heat sink plate 50, and an adhesive layer 41. The frame 80 is made of a first material, and an external terminal electrode 90 is attached to the frame 80. The heat sink plate 50 supports the frame 80, has an unmounted region 55U in the frame 80 on which the power semiconductor element 200 is to be mounted, and is made of non-composite material including copper with a purity of 95.0 weight% or more. The adhesive layer 41 is made of a second material different from the first material, and bonds the frame 80 and the heat sink plate 50.SELECTED DRAWING: Figure 1

Description

The present invention relates to a package and a method for manufacturing a power semiconductor module, in particular, a package for forming a sealing space for sealing a power semiconductor element without a gloss leak by attaching a lid, and a package without a gloss leak. It relates to a sealed power semiconductor device.

Depending on the type and application of the power semiconductor element, the container forming the sealing space for sealing the power semiconductor element may be required to have high airtightness to the extent that gloss leakage does not occur. In particular, high-frequency semiconductor devices are often required to be sealed without gloss leaks. In this specification, a container that constitutes a sealing space for sealing a power semiconductor element by attaching a lid is also referred to as a package. The package has a cavity, and the cavity is sealed by the lid to provide a sealing space. The power semiconductor device is mounted on the package in the cavity before the lid is attached to the package.

According to the technique of JP-A-2005-150133 (Patent Document 1), first, the heat sink plate, the ceramic frame, and the external connection terminal are connected to each other. This prepares a package with cavities. The heat sink is made of a composite material. Examples of the composite material include a Cu-W-based composite metal plate, a Cu-Mo-based composite metal plate, and a clad composite metal plate in which Cu plates are bonded to both sides of a Cu-Mo-based alloy metal plate. Has been done. The heat sink plate and the ceramic frame are joined by Ag-Cu brazing at about 780 ° C to 900 ° C. A high-frequency semiconductor element is mounted on this package. Then, the cavity is sealed by adhering the lid body to the upper surface portion of the ceramic frame body. In other words, the high frequency semiconductor element is airtightly sealed in the sealing space.

By using the composite material as the material of the heat sink as described above, the coefficient of thermal expansion of the heat sink can be brought close to the coefficient of thermal expansion of the ceramic frame and the semiconductor element. This makes it possible to prevent destruction due to the difference in thermal expansion and contraction. Therefore, it is permissible to bond the ceramic frame and the semiconductor element onto the heat sink plate at a high temperature. In the above technique, when the semiconductor element is mounted, the heat sink plate and the ceramic frame are already joined to each other. In order to mount the semiconductor element so that the bonding is not impaired, there is a restriction that the semiconductor element must be mounted at a temperature lower than the bonding temperature of the ceramic frame. In the above technique, the ceramic frame is joined at a high temperature of about 780 ° C. to 900 ° C., so that the joining is hardly adversely affected by heating at about the mounting temperature of the semiconductor element. Further, since the coefficient of thermal expansion of the heat sink plate is close to the coefficient of thermal expansion of the semiconductor element, it is possible to prevent the semiconductor element from being destroyed due to thermal stress during mounting even if the mounting temperature is slightly high. Therefore, the semiconductor element can be mounted by brazing, for example, at a mounting temperature of about 400 ° C., which is relatively high.

According to the technique of JP-A-2003-282751 (Patent Document 2), Cu or a Cu-based metal plate is used as the heat sink plate. Cu is an extremely excellent material in that a high thermal conductivity exceeding 300 W / m · K can be easily obtained while being relatively inexpensive. Therefore, unlike the technique of JP-A-2005-150133 described above in which the heat sink plate is made of a composite material, a heat sink plate having high thermal conductivity can be obtained at low cost. According to this technique, first, a semiconductor element is mounted on a heat sink plate by brazing. Next, the frame body to which the external connection terminals are bonded in advance is joined on the heat sink plate so as to surround the semiconductor element. By using a low melting point bonding material for this bonding, the frame is bonded at a temperature lower than the brazing temperature of the semiconductor element. Next, the cavity is sealed by joining the lid to the upper surface side of the frame. In other words, the semiconductor element is airtightly sealed in the sealing space. As a result, a high frequency power module can be obtained.

Japanese Unexamined Patent Publication No. 2005-150133 JP-A-2003-282751

According to the technique of JP-A-2003-282751, the cavity of the package is formed by joining the frame to the heat sink plate after mounting the semiconductor element. Therefore, in this technique, the process after mounting the semiconductor element is more complicated than the technique of JP-A-2005-150133 described above. This hinders the rapid completion of the semiconductor module after mounting the semiconductor element. This is not desirable for semiconductor module manufacturers.

The present invention has been made to solve the above problems, and an object of the present invention is to quickly complete a power semiconductor module after mounting a power semiconductor element while using a heat sink plate having high thermal conductivity. It is to provide a package and a method for manufacturing a power semiconductor module.

The package of the present invention is for forming a sealing space for sealing a power semiconductor element without gloss leak by attaching a lid, and is bonded to an external terminal electrode, a frame, and a heat sink. Has a layer. The frame is made of a first material and is attached with an external terminal electrode. The heat sink plate supports the frame, has an unmounted region in the frame on which the power semiconductor element will be mounted, and is made of a non-composite material having a purity of 95.0% by weight or more and containing copper. Become. The adhesive layer is made of a second material different from the first material, and the frame body and the heat sink plate are bonded to each other.

The method for manufacturing a power semiconductor module of the present invention has the following steps. It supports an external terminal electrode, a frame made of a first material and to which an external terminal electrode is attached, and has an unmounted region in the frame, and contains copper at a purity of 95.0% by weight or more. A package including a heat sink plate made of a non-composite material and an adhesive layer made of a second material different from the first material and adhering the frame body and the heat sink plate to each other is prepared. The power semiconductor element is mounted on the unmounted region of the heat sink plate. By mounting the lid on the frame, the power semiconductor element is sealed without gloss leak.

According to the present invention, the heat sink is made of a non-composite material having a purity of 95.0 weight percent or more and containing copper. As a result, high thermal conductivity can be easily obtained. Further, before mounting the power semiconductor element, the heat sink plate has an unmounted region in the frame on which the power semiconductor element will be mounted. In other words, when the power semiconductor element is mounted, the frame is already mounted on the heat sink plate. Therefore, the step of mounting the frame on the heat sink plate after mounting the power semiconductor element is not required. From the above, it is possible to quickly complete the power semiconductor module after mounting the power semiconductor element while using the heat sink plate having high thermal conductivity.

The objects, features, aspects, and advantages of the present invention will be made clearer by the following detailed description and accompanying drawings.

It is sectional drawing which shows schematic structure of the power semiconductor module in one Embodiment of this invention. It is sectional drawing which shows schematic structure of the package for a power semiconductor module in one Embodiment of this invention. It is sectional drawing which shows roughly the 1st step of the manufacturing method of the power semiconductor module in one Embodiment of this invention. It is sectional drawing which shows typically the 2nd step of the manufacturing method of the power semiconductor module in one Embodiment of this invention. It is sectional drawing which shows roughly one step of the manufacturing method of the package in one Embodiment of this invention. It is sectional drawing which shows schematic structure of the power semiconductor module of 1 comparative example. It is sectional drawing which shows schematic structure of the power semiconductor module of another comparative example. FIG. 5 is a cross-sectional view schematically showing a first step of the method for manufacturing a power semiconductor module shown in FIG. 7. FIG. 5 is a cross-sectional view schematically showing a second step of the method for manufacturing a power semiconductor module shown in FIG. 7. FIG. 5 is a cross-sectional view schematically showing a modified example of one step of the package manufacturing method shown in FIG. It is sectional drawing which shows typically the modification of the structure of the package shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Constitution)
FIG. 1 is a cross-sectional view schematically showing the configuration of the power semiconductor module 900 according to the present embodiment. The power semiconductor module 900 has a package 100 (details will be described later with reference to FIG. 2), a power semiconductor element 200, and a lid 300.

The power semiconductor element 200 may be a high frequency semiconductor element. A high-frequency semiconductor element is a semiconductor element that operates at a frequency of approximately several tens of MHz (for example, 30 MHz) or more and 30 GHz or less. In this case, the power semiconductor module 900 is a high frequency module. The power semiconductor device 200 suitable for high frequency applications is typically an LDMOS (lateral diffused MOS) transistor or a GaN (gallium nitride) transistor.

The power semiconductor element 200 is arranged on the mounting area 55M of the heat sink plate 50 of the package 100. The mounting region 55M and the power semiconductor device 200 are preferably bonded to each other via a bonding layer 42 containing a thermosetting resin and a metal. The thermosetting resin of the bonding layer 42 preferably contains an epoxy resin. The metal of the bonding layer 42 preferably contains silver.

A lid 300 is attached to the package 100. As a result, a sealing space 950 for sealing the power semiconductor element 200 without gloss leakage is configured. Therefore, the power semiconductor element 200 is highly airtight and is protected from the external environment so that water vapor and other gases in the atmosphere do not enter. The sealing space 950 preferably has environmental resistance to 500 cycles of temperature change between −65 ° C. and + 150 ° C. Specifically, it is preferable that the sealing space 950 does not have a gloss leak even after being exposed to the above temperature change.

FIG. 2 is a cross-sectional view schematically showing the configuration of the package 100 in the present embodiment. Package 100 will be used for manufacturing the power semiconductor module 900 (FIG. 1). The package 100 is for forming a sealing space 950 (FIG. 1) by attaching the lid 300 (FIG. 1). The sealing space 950 (FIG. 1) seals the power semiconductor element 200 (FIG. 1) without gloss leakage. Package 100 has a cavity 110 that serves as a sealing space 950 (FIG. 1). The package 100 has an external terminal electrode 90, a frame body 80, a heat sink plate 50, and an adhesive layer 41.

The frame body 80 is made of a first material (hereinafter, also referred to as “material of the frame body 80”). The material of the frame 80 preferably has heat resistance to heat treatment at 260 ° C. for 2 hours. The material of the frame body 80 preferably contains a first resin (hereinafter, also referred to as “resin of the frame body 80”). The resin of the frame 80 is preferably a thermoplastic resin.

It is preferable that an inorganic filler (first inorganic filler) is dispersed in the resin of the frame body 80. The inorganic filler in the resin of the frame 80 preferably contains at least one of fibrous particles and plate-like particles. The fibrous or plate-like shape prevents the filler from inhibiting the flow of the resin when the frame 80 is formed by an injection molding technique or the like. The material of such inorganic fillers include silica glass fiber, alumina fiber, carbon fiber, talc _{(3MgO · 4SiO 2 · H 2} O), wollastonite, mica, graphite, calcium carbonate, dolomite, glass flakes, Glass beads, barium sulfate and titanium oxide are used. The size of the inorganic filler made of talc on a flat plate is, for example, a particle size of 1 μm to 50 μm. Here, the particle size is an arithmetic mean value of the major axis obtained by observing the cross section of the resin. The coefficient of thermal expansion of the inorganic filler is preferably 17 ppm / K or less in view of the coefficient of thermal expansion of copper. The content of the inorganic filler is preferably 30 wt% to 70 wt%.

An external terminal electrode 90 is attached to the frame body 80. The external terminal electrode 90 is made of metal, preferably having a purity of 90 wt% (weight percent) or more and containing copper. In addition, instead of the material containing copper with high purity as described above, Kovar (trademark) or an iron / nickel alloy may be used. The surface of the external terminal electrode 90 may be nickel-plated or gold-plated on the nickel plating for the purpose of ensuring bondability with the bonding wire 205 or the like.

The heat sink plate 50 supports the frame body 80. The heat sink plate 50 is made of a non-composite material having a purity of 95.0 wt% or more, preferably 99.8 wt% or more and containing copper. From the viewpoint of heat resistance, the copper content of the heat sink plate 50 is preferably less than 100 wt%.

The heat sink plate 50 has an inner surface 51 surrounded by a frame body 80. The inner surface 51 has an unmounted region 55U on which the power semiconductor element 200 (FIG. 1) is mounted and a peripheral region 54 on which the power semiconductor element 200 is not mounted. The unmounted area 55U is an area in which the power semiconductor element 200 is mounted, although the power semiconductor element 200 is not mounted. In other words, of the inner surface 51 of the package 100, the portion that becomes the mounting area 55M (FIG. 1) when the power semiconductor element 200 (FIG. 1) is mounted is the unmounted area 55U. The unmounted area 55U is preferably exposed. The heat sink plate 50 has an outer surface (lower surface in FIG. 2) opposite to the inner surface 51. The outer surface is usually attached to other members when the power semiconductor module 900 is used, but may be exposed when the power semiconductor module 900 is manufactured.

The adhesive layer 41 adheres the frame body 80 and the heat sink plate 50 to each other. The adhesive layer 41 is made of a second material (hereinafter, also referred to as “material of the adhesive layer 41”) different from the material of the frame body 80. The material of the adhesive layer 41 preferably contains a second resin (hereinafter, also referred to as "resin of the adhesive layer 41"). The resin of the adhesive layer 41 is preferably a thermosetting resin from the viewpoint of heat resistance and high fluidity before curing.

It is preferable that an inorganic filler (second inorganic filler) is dispersed in the resin of the adhesive layer 41. The inorganic filler in the resin of the adhesive layer 41 preferably contains at least one of silica glass and silica, and is more preferably made of silica glass. Typically, the coefficient of thermal expansion of silica glass is about 0.5 ppm / K, the coefficient of thermal expansion of crystalline silica is about 15 ppm / K, and therefore the coefficient of thermal expansion of the inorganic filler is 17 ppm / K or less. can do. This is particularly desirable when an epoxy resin or a fluororesin is used as the resin of the adhesive layer 41. In this case, the content of the inorganic filler is preferably 50 wt% to 90 wt%. Even if at least one of alumina, aluminum hydroxide, talc, iron oxide, wollastonite, calcium carbonate, mica, titanium oxide, and carbon fiber is used in place of, or in combination with, at least one of silica glass and silica. Good. The shape of the inorganic filler is, for example, spherical, fibrous, or plate-like. On the other hand, when a silicone resin is used as the resin of the adhesive layer 41, since the frame 80 has rubber elasticity, the limitation of the coefficient of thermal expansion of the inorganic filler can be almost ignored. In this case, the content of the inorganic filler may be adjusted from the viewpoint of controlling the fluidity of the adhesive layer 41, and is preferably 1 wt% to 10 wt%. From the viewpoint of ensuring the fluidity of the adhesive layer 41 before curing, spherical silica glass (non-crystalline silica) having a particle size of 1 μm to 50 μm is optimal. Here, the particle size indicates the arithmetic mean diameter measured by observing the cross section of the resin.

The adhesion by the adhesive layer 41 has airtightness. This airtightness is preferably heat resistant to heat treatment at 260 ° C. for 2 hours. In other words, the airtightness between the heat sink plate 50 and the frame 80 is preferably heat resistant to heat treatment at 260 ° C. for 2 hours. To test whether the airtightness between the heat sink plate 50 and the frame 80 has heat resistance to the heat treatment at 260 ° C. for 2 hours, the package 100 (FIG. 2) is heat-treated at 260 ° C. for 2 hours. After the heat treatment, the lid 300 may be attached to the package 100 with sufficient airtightness and a gloss leak test may be performed. If the lid 300 and its mounting structure have sufficient heat resistance, the lid 300 may be mounted before the heat treatment.

(Production method)
Next, a method of manufacturing the power semiconductor module 900 (FIG. 1) will be described. First, package 100 (FIG. 2) is prepared.

Next, the power semiconductor element 200 is mounted on the unmounted region 55U of the heat sink plate 50. As a result, the exposed unmounted region 55U (FIG. 2) becomes the mounted region 55M (FIG. 3) covered by the power semiconductor element 200. When the power semiconductor element 200 is mounted, it is preferable that the unmounted region 55U of the heat sink plate 50 and the power semiconductor element 200 are bonded to each other via a bonding layer 42 containing a thermosetting resin and a metal. This bonding is preferably carried out by applying a paste-like adhesive containing a thermosetting resin and a metal, and curing the adhesive. The thermosetting resin of the bonding layer 42 preferably contains an epoxy resin. The metal of the bonding layer 42 preferably contains silver.

With reference to FIG. 4, the power semiconductor module 900 and the external terminal electrode 90 are then connected by the bonding wire 205 in the cavity 110. This ensures an electrical connection between the power semiconductor module 900 and the external terminal electrode 90. The electrical connection between the power semiconductor module 900 and the external terminal electrode 90 may be secured by a method other than the bonding wire 205, and in that case, the bonding wire 205 is not always necessary.

With reference to FIG. 1 again, the power semiconductor element 200 is then sealed without gross leakage by mounting the lid 300 on the frame 80. As a result, the power semiconductor module 900 is obtained. The lid 300 is attached to the package 100 so as not to give heat damage to the package 100 on which the power semiconductor element 200 is mounted so as to cause a gloss leak. In other words, the lid 300 is attached to the package 100 so as not to cause heat damage to the adhesive layer 41 so as to cause gloss leak. For example, the lid 300 is attached to the package 100 via an adhesive layer 46 that has been cured at a curing temperature low enough not to lead to the thermal damage described above. This curing temperature is, for example, less than 260 ° C.

Next, a method of manufacturing the package 100 (FIG. 2) will be described. With reference to FIG. 5, first, a heat sink plate 50 and a frame body 80 to which the external terminal electrodes 90 are attached are prepared. The frame body 80 to which the external terminal electrode 90 is attached can be formed by integrally molding the external terminal electrode 90 made of metal and the frame body 80 made of resin. Next, the adhesive 41h is applied to the lower surface of the frame body 80. Next, as shown by the broken line arrow in the figure, the lower surface of the frame body 80 is attached to the upper surface of the heat sink plate 50 via the adhesive 41h. The adhesive layer 41 (FIG. 2) is formed by curing the adhesive 41h. This gives Package 100.

(Comparison example)
With reference to FIG. 6, the power semiconductor module 900A of the comparative example has a package 100A. The package 100A has a frame body 80A, a heat sink plate 50A, and an adhesive layer 41A. The frame body 80A is made of ceramic and therefore has high heat resistance. The heat sink plate 50A is made of a composite material. Specifically, the heat sink plate 50A has a laminated structure composed of a Cu-Mo layer 58B and Cu layers 59A provided on the upper surface and the lower surface thereof.

By using the above-mentioned composite material as the material of the heat sink plate 50A, the coefficient of thermal expansion of the heat sink plate 50A can be brought close to the coefficient of thermal expansion of the frame body 80A made of ceramic and the power semiconductor element 200. This makes it possible to prevent destruction due to the difference in thermal expansion and contraction. Therefore, it is permissible to bond the frame body 80A and the power semiconductor element 200 onto the heat sink plate 50A at a high temperature.

In this comparative example, when the power semiconductor element 200 is mounted, the heat sink plate and the frame are already joined to each other as in the above-described embodiment. In order to mount the power semiconductor element 200 so that the bonding is not impaired, there is a restriction that the power semiconductor element 200 must be mounted at a temperature lower than the bonding temperature of the frame 80A. In this comparative example, since the frame body 80A itself has high heat resistance and the difference between the coefficient of thermal expansion of the frame body 80A and the coefficient of thermal expansion of the heat sink plate 50A is small, the frame body 80A and the heat sink plate 50A are used. Can be joined at a high temperature of about 780 ° C. to 900 ° C. Therefore, this junction is hardly adversely affected when exposed to the mounting temperature of the power semiconductor device 200, which is a lower temperature. Further, since the coefficient of thermal expansion of the heat sink plate 50A is close to the coefficient of thermal expansion of the power semiconductor element 200, it is possible to prevent the power semiconductor element 200 from being destroyed due to thermal stress during mounting even if the mounting temperature is slightly high. .. Therefore, the bonding layer 42A for mounting the power semiconductor element 200 can be formed by brazing at a high temperature of, for example, about 400 ° C.

In this comparative example, it is necessary to use a composite material as the material of the heat sink plate 50A in order to adjust the coefficient of thermal expansion. Therefore, unlike the case of the heat sink plate 50 (FIG. 1: the present embodiment), a non-composite material having copper as a main component cannot be used. A non-composite material made of high-purity copper is an extremely excellent material in that a high thermal conductivity exceeding 300 W / m · K can be easily obtained while being relatively inexpensive. Such an excellent material cannot be used in this comparative example. Therefore, in this comparative example, it is not easy to make the thermal conductivity of the heat sink plate 50A higher than 300 W / m · K.

Next, a method of manufacturing the power semiconductor module 900B (FIG. 7) of another comparative example will be described below. With reference to FIG. 8, first, the power semiconductor element 200 is mounted on the heat sink plate 50 by using the bonding layer 42. Next, the adhesive 41Bh is applied to the lower surface of the frame body 80B. Next, as shown by the broken line arrow in the figure, the lower surface of the frame body 80B is attached onto the upper surface of the heat sink plate 50 via the adhesive 41Bh. The adhesive layer 41B (FIG. 9) is formed by curing the adhesive 41Bh. This gives Package 100. Next, the power semiconductor module 900B is obtained by joining the lid 300 to the upper surface side of the frame 80B as in the above-described embodiment.

In this comparative example, the power semiconductor element 200 is already mounted by the bonding layer 42 (FIG. 8) before the frame body 80B is mounted by the adhesive layer 41B (FIG. 9). Therefore, the adhesive layer 41B and the frame 80B are not exposed to high temperature treatment for mounting the power semiconductor element 200. Therefore, the structure and material of the adhesive layer 41B and the frame body 80B can be determined without much consideration for heat resistance. On the other hand, in this comparative example, a step of adhering the frame body 80B is required after mounting the power semiconductor element 200. Therefore, the process after mounting the power semiconductor element 200 is complicated. This hinders the rapid completion of the power semiconductor module 900B after mounting the power semiconductor element 200. This is not preferable for the manufacturer of the power semiconductor module 900B.

(Summary of effect)
According to this embodiment, the heat sink plate 50 (FIG. 1) is made of a non-composite material having a purity of 95.0 wt% or more and containing copper. As a result, a high thermal conductivity exceeding 300 W / m · K can be easily obtained. For example, a material of Japanese Industrial Standards (JIS) C1510 (purity of 99.82 wt% or more and containing copper) can obtain a high thermal conductivity of 347 W / m · K. Further, before mounting the power semiconductor element 200, the heat sink plate 50 has an unmounted region 55U (FIG. 2) in the frame 80 on which the power semiconductor element 200 will be mounted. In other words, when the power semiconductor element 200 is mounted, the frame 80 is already mounted on the heat sink plate 50. Therefore, the step of mounting the frame 80 on the heat sink plate 50 after mounting the power semiconductor element 200 is not required. From the above, it is possible to quickly complete the power semiconductor module 900 after mounting the power semiconductor element 200 while using the heat sink plate 50 having a high thermal conductivity.

The airtightness between the heat sink plate 50 and the frame 80 is preferably heat resistant to heat treatment at 260 ° C. for 2 hours. As a result, even if a thermal load corresponding to a heat treatment at 260 ° C. for 2 hours is applied at the time of mounting the power semiconductor element 200, it can be avoided that it causes a gloss leak in the sealing space 950 (FIG. 1).

The sealing space 950 (FIG. 1) is preferably environmentally resistant to 500 cycles of temperature change between −65 ° C. and + 150 ° C. As a result, the power semiconductor element 200 can be maintained in an airtight atmosphere even under a relatively severe temperature change. Therefore, the reliability of the power semiconductor element 200 can be more reliably maintained.

The unmounted area 55U (FIG. 2) is preferably exposed. As a result, the power semiconductor element 200 (FIG. 1) can be easily mounted on the unmounted region 55U (FIG. 2).

The material of the frame 80 preferably contains a resin. As a result, brittle fracture due to thermal stress from the heat sink plate 50 to the frame 80 is less likely to occur. The resin of the frame 80 is preferably a thermoplastic resin. As a result, the frame body 80 can be formed with high productivity by using injection molding technology or the like. It is preferable that the inorganic filler is dispersed in the resin of the frame body 80. As a result, the coefficient of thermal expansion of the frame body 80 can be brought close to the coefficient of thermal expansion of the heat sink plate 50. The inorganic filler in the resin of the frame 80 preferably contains at least one of fibrous particles and plate-like particles. As a result, when the frame body 80 is formed by injection molding technology or the like, it is possible to prevent the filler from inhibiting the flow of the resin.

The material of the adhesive layer 41 preferably contains a resin. As a result, the thermal stress applied from the heat sink plate 50 to the frame body 80 via the adhesive layer 41 is relaxed. Therefore, the frame 80 is less likely to be broken due to thermal stress. The resin of the adhesive layer 41 is preferably a thermosetting resin. As a result, the heat resistance of the adhesive layer 41 can be enhanced, and the fluidity can be easily ensured before curing. This fluidity is important for ensuring the productivity of the process of forming the adhesive layer 41. If the fluidity is low, it is difficult to use methods such as printing, dispensing and spraying. It is preferable that the inorganic filler is dispersed in the resin of the adhesive layer 41. As a result, the coefficient of thermal expansion of the adhesive layer 41 can be brought close to the coefficient of thermal expansion of the heat sink plate 50. Therefore, it is possible to prevent fracture due to thermal stress under high temperature or temperature cycle. As described above, the inorganic filler in the resin of the adhesive layer 41 preferably contains at least one of silica glass and silica, and more preferably made of silica glass. As a result, the coefficient of thermal expansion of the inorganic filler can be set to 17 ppm / K or less in view of the coefficient of thermal expansion of copper.

When the power semiconductor element 200 is mounted, the unmounted region 55U (FIG. 2) of the heat sink plate 50 and the power semiconductor element 200 are connected to each other via a bonding layer 42 (FIG. 1) containing a thermosetting resin and a metal. It is preferable that they are joined to each other. Since the bonding layer 42 contains a metal, the heat dissipation from the power semiconductor element 200 to the heat sink plate 50 can be improved. Further, when the bonding layer 42 contains the resin, the thermal stress applied from the heat sink plate 50 to the power semiconductor element 200 via the bonding layer 42 is relaxed. As a result, the power semiconductor element 200 is less likely to be destroyed due to thermal stress.

(Modification example)
FIG. 10 is a cross-sectional view schematically showing a modified example of one step (FIG. 5) of the manufacturing method of the package 100. In this modification, the adhesive 41h is applied not to the lower surface of the frame 80 but to the upper surface of the heat sink plate 50. Other than this, the same steps as in the above-described embodiment are performed. The adhesive 41h may be applied to both the lower surface of the frame body 80 and the upper surface of the heat sink plate 50.

FIG. 11 is a cross-sectional view schematically showing the package 100v of the modified example of the package 100 (FIG. 2). In this modification, the lower surface of the external terminal electrode 90 is attached to the frame body 80v by the adhesive layer 44v. Further, an additional frame body 80u is attached to the upper surface of the external terminal electrode 90 by an adhesive layer 44u. According to this modification, there is no need for a technique for integrally molding the external terminal electrode 90 made of metal and the frame 80 made of resin. The additional frame 80u may be omitted as long as the lid 300 (FIG. 1) can be attached with sufficient strength.

(Examples and reference examples)
Tables 1 and 2 below show the package configurations of Examples (Nos. 1 to 25) and Reference Examples (Nos. 101 to 120) and the results of gross leak tests performed on them. In the table, the "adhesive layer" is the adhesive layer between the heat sink plate and the frame, and the "electrode" is the external terminal electrode.

The filler content of the adhesive layer was 82 wt% in the case of silica glass and 5 wt% in the case of silica. Although detailed description is omitted, it is considered that there is no significant effect even if the silica glass content is changed within the range of 50 wt% to 90 wt% instead of 82 wt%. Further, even if the silica content is changed within the range of 1 wt% to 10 wt% instead of 5 wt%, it is considered that there is no significant effect. When the filler for the frame was "Yes", the filler made of talc was added at 46 wt%. Even if the content of this filler is changed within the range of 30 wt% to 70 wt% instead of 46 wt%, it is considered that there is no significant effect. As the material of the electrode, a copper alloy (Japanese Industrial Standards (JIS) C1940) or Kovar was used. The heat sink plate had dimensions of 32 mm × 10 mm and a thickness dimension of 1.7 mm in a plan view.

For the packages in Table 1, the gloss leak test was performed after leaving at a high temperature, and the gloss leak test was performed again after the subsequent temperature cycle. For the packages in Table 2, the gross leak test was performed only after being left at a high temperature. The high temperature standing was performed by leaving the package in an environment of 260 ° C. for 2 hours. This heating condition is close to the heating condition in the mounting process of the power semiconductor element. The temperature cycle was performed by 500 cycles of temperature change between -65 ° C and + 150 ° C. This temperature cycle mimics the temperature changes exposed to power semiconductor modules installed in harsh external environments. Therefore, even a package in which gloss leak is observed after a temperature cycle can be practically used in a relatively mild environment. On the other hand, packages used in harsh external environments need to be free of gross leaks after the temperature cycle.

The gloss leak test after leaving at a high temperature is performed by leaving the package without the lid attached in an environment of 260 ° C. for 2 hours, and then attaching the lid made of liquid crystal polymer with an adhesive at an adhesion temperature of 190 ° C. It was carried out for the constructed structure. As this adhesive, the same resin as the resin (second resin) of the adhesive layer used for joining the heat sink and the frame was used. The gloss leak test after the temperature cycle was performed on the structure that passed the gloss leak test after being left at a high temperature. In the gloss leak test, specifically, fluorinert ™, which is a high boiling point solvent, was heated to 120 ° C. ± 10 ° C., and the structure was immersed in this solvent for 30 seconds. The presence or absence of a leak was determined based on whether or not bubbles were generated during this immersion.

To supplement the results in Table 1 above, No. 1 and No. Only the former of 3 did not show gross leak after the temperature cycle. It is presumed that the reason for this is that the filler in the adhesive layer suppressed the thermal expansion of the adhesive layer.

No. 1 and No. Only the former of 2 did not show gross leak after the temperature cycle. The reason for this is that the difference between the thermal expansion of the external terminal electrode 90 and the thermal expansion of other members is smaller when a copper alloy having a relatively large coefficient of thermal expansion is used instead of Kovar having a relatively small coefficient of thermal expansion. It is presumed that it can be done.

No. 5 and No. No gross leak was observed in both of No. 6 after being left at a high temperature, but no gross leak was observed only in the latter after the temperature cycle. The reason for this is No. In No. 6, it is presumed that the filler in the adhesive layer suppressed the permeation of gas in the adhesive layer.

No. In No. 13, gross leak was observed after the temperature cycle. It is presumed that the reason for this is that the coefficient of thermal expansion of Teflon (registered trademark) is as large as about 100 ppm / K. Therefore, it is presumed that the coefficient of thermal expansion of the material of the frame is preferably smaller than the coefficient of thermal expansion of Teflon (about 100 ppm / K).

No. 23-No. No. 25 out of 25 23 and No. Only 24 had no gross leak after the temperature cycle. It is presumed that the reason for this is that the coefficient of thermal expansion of zirconia and forsterite is 10 ppm / K, which is larger than the coefficient of thermal expansion of alumina of 7 to 8 ppm / K. From the viewpoint of easy optimization of the coefficient of thermal expansion, it is considered that the frame is preferably a resin or an inorganic filler-containing resin instead of ceramic.

To supplement the results in Table 2 above, No. 101-No. Gross leaks were observed in each of the 120 after being left at a high temperature. Therefore, subsequent temperature cycle tests were omitted. The reason why gross leak was caused only by leaving at high temperature is No. 1-No. Compared to the adhesive layer of No. 25 (Table 1), No. 101-No. It is presumed that the heat resistance of the adhesive layer of 120 (Table 2) is low.

Although the present invention has been described in detail, the above description is exemplary in all aspects and the invention is not limited thereto. It is understood that a myriad of variations not illustrated can be envisioned without departing from the scope of the invention.

41 Adhesive layer 41h Adhesive 42 Bonding layer 50 Heat sink plate 51 Inner surface 54 Peripheral area 55M Mounting area 55U Unmounted area 80,80v Frame 90 External terminal electrode 100,100v Package 110 Cavity 200 Power semiconductor element 205 Bonding wire 300 Lid 900 Power semiconductor module 950 Encapsulation space

Claims (14)

It is a package for forming a sealing space for sealing a power semiconductor element without gloss leak by attaching a lid.
With external terminal electrodes
A frame made of the first material and to which the external terminal electrodes are attached, and
A heat sink plate made of a non-composite material that supports the frame and has an unmounted region in the frame on which the power semiconductor element is to be mounted and has a purity of 95.0% by weight or more and contains copper.
An adhesive layer made of a second material different from the first material and adhering the frame body and the heat sink plate to each other.
Package with. The package according to claim 1, wherein the airtightness between the heat sink plate and the frame body has heat resistance to heat treatment at 260 ° C. for 2 hours. The package according to claim 1 or 2, wherein the sealing space is environmentally resistant to 500 cycles of temperature changes between −65 ° C. and + 150 ° C. The package according to any one of claims 1 to 3, wherein the unmounted area is exposed. The package according to any one of claims 1 to 4, wherein the first material of the frame contains a first resin. The package according to claim 5, wherein the first resin is a thermoplastic resin. The package according to claim 5 or 6, wherein the first inorganic filler is dispersed in the first resin. The package according to claim 7, wherein the first inorganic filler contains at least one of fibrous particles and plate-like particles. The package according to any one of claims 1 to 8, wherein the second material of the adhesive layer contains a second resin. The package according to claim 9, wherein the second resin is a thermosetting resin. The package according to claim 9 or 10, wherein the second inorganic filler is dispersed in the second resin. The package according to claim 11, wherein the second inorganic filler contains at least one of silica glass and silica. An external terminal electrode, a frame made of a first material to which the external terminal electrode is attached, and a frame body that supports the frame body and has an unmounted region in the frame body, and copper having a purity of 95.0% by weight or more. A step of preparing a package including a heat sink plate made of a non-composite material containing the above material and an adhesive layer made of a second material different from the first material and adhering the frame body and the heat sink plate to each other.
A process of mounting a power semiconductor element on the unmounted region of the heat sink plate, and
A step of sealing the power semiconductor element without gloss leak by mounting a lid on the frame, and
A method for manufacturing a power semiconductor module. 13. The step of mounting the power semiconductor element includes a step of joining the unmounted region of the heat sink plate and the power semiconductor element to each other via a bonding layer containing a thermosetting resin and a metal. A method for manufacturing a power semiconductor module according to.

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