JP5333077B2 - Resin molded body - Google Patents

Description

  The present invention relates to a resin molded body having a wiring electrode plate for supplying a current to a power element as a housing of a power module.

  In recent years, the importance of inverter power converters has been increasing for the effective use of energy resources and protection of the global environment, and the need for miniaturization and high reliability of inverter power converters has also increased. In order to reduce the size and increase the reliability of the inverter power converter, it is essential to operate the power module of the main converter efficiently. In other words, it is desirable that the power module can be energized to a value as close as possible to the allowable upper limit value of the energization rating such as the voltage and current of the power module.

  However, in reality, due to manufacturing variations of semiconductor chips built in the power module and external circuit factors, it is necessary to provide a device configuration in which a safety margin is added to the energized current / voltage. As an external circuit factor, there is a switching surge voltage generated by circuit inductance. Since the value obtained by subtracting the surge voltage from the maximum voltage that can be applied to the semiconductor chip is the voltage that can be actually energized, the voltage that can actually be energized increases if the generated surge voltage is suppressed to a small value. The restriction on the energizable voltage relatively increases the size of the device. In addition, the repetition of a large surge voltage results in electrical stress accumulation in the element, which reduces reliability.

The switching surge voltage ΔV (unit V) when the switching element is turned off is expressed as follows: circuit inductance is L (unit H) and current change rate is di / dt (unit A / s).
ΔV = −L · di / dt
It is represented by
Since the switching element is aimed at improving the switching speed and it is not preferable to suppress the current change rate, it is necessary to reduce the circuit inductance L of the wiring. In order to reduce the circuit inductance, it is necessary to reduce the inductance parasitic on the internal wiring of the power module. For that purpose, the internal wiring shape of the power module, mutual positional relationship, and the shape of the external wiring are important elements, and various configurations and structures have been proposed.

  For example, in a power module, by arranging a flexible flexible insulating sheet between the flat wiring 1 and the wiring 2 facing each other in parallel, the wiring 1 and the wiring 2 are arranged in close proximity to each other to reduce inductance. Is known (see Patent Document 1). Similarly, in a power conversion device, one that reduces inductance by including a DC wiring 1 and a DC wiring 2 with a thin insulating film to form a close parallel arrangement is known (see Patent Document 2). If the methods described in these documents are taken, the first DC wiring electrode plate and the second DC wiring electrode plate are insulated from the first DC wiring electrode plate and the second DC wiring electrode plate while the plate surfaces are parallel wiring. The distance between the plate surfaces of the DC wiring electrode plates can be shortened. As a result, negative mutual inductance is generated and the self-inductance is offset to reduce the inductance of the DC circuit.

Japanese Patent No. 2725952 JP 2004-63675 A

  However, the methods shown in these documents have a problem that the DC wiring electrode plate is arranged as a component separate from the casing, and the number of assembling steps increases. Further, when the DC wiring electrode plate is integrated with the casing by insert molding, the pressure of the resin to be injection-molded is applied to the insert part. At this time, in order to ensure insulation between the DC wiring electrode plates, the end portion of the insulating sheet (insulating film) is exposed from the DC wiring electrode plate. In the above method, the strength of the insulating sheet (insulating film) is low, and there is a concern that the shape of the end portion is deformed at the time of injection molding, and there is a problem that insulation between the DC wiring electrode plates cannot be secured.

  As another method, a predetermined interval is provided between the DC wiring electrode plates, and when integrating by insert molding, the interval is filled with a molding resin and integrated. In this case, it is necessary to have a resin thickness to ensure insulation and a flow path interval through which the resin enters. Therefore, it is difficult to shorten the distance between the DC wiring electrode plates, and the inductance is reduced. There is a problem that the effect cannot be obtained.

  The problem to be solved by the present invention is to reduce the distance between the plate surfaces of the first DC wiring electrode plate and the second DC wiring electrode plate that are configured in the casing of the power module, and to reduce the internal wiring of the power module. It is providing the resin molding which can reduce the parasitic inductance. As a result, it is possible to provide a power semiconductor module and a power conversion device that have a small generated surge voltage, a high energizable voltage, a small size and high reliability. Moreover, the man-hour at the time of an assembly can also be reduced.

  In order to achieve the above object, a resin molded body according to the present invention is a resin molded body having a first DC wiring electrode plate and a second DC wiring electrode plate as insert parts, the first DC wiring The electrode plate and the second DC wiring electrode plate are arranged so that the plate surfaces are parallel to each other through an insulating plate in which one or two or more are stacked. And the said insulating board is what heat-press-molded the prepreg which impregnated and dried the thermosetting resin in the sheet-like glass fiber base material, and the total thickness of the said insulating board is 0.3 mm or more and 1 mm or less (Claim 1).

  Preferably, the glass transition temperature of the insulating plate is 150 ° C. or higher (Claim 2), and the relative dielectric constant of the insulating plate is 7 or higher (Claim 3). More preferably, the thermosetting resin is an epoxy resin containing 30% by mass or more of barium titanate (Claim 4).

  Preferably, the insulating plate has a thickness of 0.2 mm or less, and is a laminate of two or more.

  The resin molded body according to the present invention is a resin molded body having a first DC wiring electrode plate and a second DC wiring electrode plate as insert parts. Thereby, the man-hour at the time of an assembly | attachment can be reduced.

  The first DC wiring electrode plate and the second DC wiring electrode plate are arranged so that the plate surfaces are parallel to each other via an insulating plate in which one or two or more are stacked. The plate is obtained by heat-pressing a prepreg obtained by impregnating and drying a sheet-like glass fiber base material with a thermosetting resin. Thereby, even when the total thickness of the insulating plate is thin, the strength of the insulating plate can be secured, and the shape of the end exposed from the DC wiring electrode plate is not deformed at the time of injection molding. As a result, insulation between the DC wiring electrode plates can be ensured, and the distance between the plate surfaces of the first DC wiring electrode plate and the second DC wiring electrode plate can be shortened. It is possible to reduce the parasitic inductance.

  Further, the insulating plate has a thickness of 0.2 mm or less, and the first DC wiring electrode plate and the second DC wiring electrode plate have a plate surface with two or more insulating plates interposed therebetween. In the case where the arrangement is made so as to be parallel, the insulating plate can follow the DC wiring electrode plate even when the DC wiring electrode plate is bent. The distance between the plate surfaces of the DC wiring electrode plate and the second DC wiring electrode plate can be set. As a result, even when the DC wiring electrode plate is bent, insulation between the electrode plates can be secured without increasing the distance between the plate surfaces of the electrode plates, so that both miniaturization and low inductance can be achieved. it can.

It is explanatory drawing which shows embodiment of the resin molding which concerns on this invention. It is explanatory drawing which shows the structure of the DC wiring electrode plate which concerns on this invention, and an insulating board. It is explanatory drawing which shows the other structure of the DC wiring electrode plate which concerns on this invention, and an insulating board.

As a specific form for carrying out the present invention, for example, a configuration as shown in FIG. 1 is desirable.
A resin molded body 1 according to the present invention is a resin molded body having a first DC wiring electrode plate 2 and a second DC wiring electrode plate 3 as insert parts. The two DC wiring electrode plates 3 are arranged so that the plate surfaces are parallel to each other via an insulating plate 4 in which one sheet or two or more sheets are overlapped (see FIG. 2). The insulating plate 4 is obtained by heat-pressing a prepreg obtained by impregnating and drying a thermosetting resin into a sheet-like glass fiber substrate, and the total thickness of the insulating plate 4 is 0.3 mm or more and 1 mm. It is characterized by the following.

  The metal material used for the first DC wiring electrode plate and the second DC wiring electrode plate is not particularly limited, but is preferably copper, aluminum, or an aluminum alloy that has high electrical conductivity and easily flows current. is there. As the thickness increases, it becomes easier for current to flow. However, considering the workability of the shape, it is preferably 1 to 3 mm. The surface can also be plated to prevent oxidation and improve surface gloss.

  The insulating plate used in the above-described configuration is manufactured by superposing a predetermined number of prepregs each having a thermosetting resin held on a sheet-like glass fiber base material and integrating them by heating and pressing. One or two or more insulating plates are overlapped and arranged between the plate surfaces of the first DC wiring electrode plate and the second DC wiring electrode plate. At this time, the total thickness of the insulating plate is set to 0.3 mm or more and 1 mm or less. If the total thickness of the insulating plates is less than 0.3 mm, the insulation between the electrode plates is not preferable, and if it exceeds 1 mm, the distance between the plate surfaces of the electrode plates increases, reducing parasitic inductance. Since the effect to do becomes small, it is not preferable.

  In addition, when the thickness of the insulating plate is 0.2 mm or less and two or more insulating plates are stacked and disposed between the first DC wiring electrode plate and the second DC wiring electrode plate, for example, FIG. As shown, the insulating plate can follow the DC wiring electrode plate even when the DC wiring electrode plate is bent. For this reason, the insulation between the electrode plates can be ensured without increasing the distance between the electrode plates even at the location where the DC wiring electrode plate is bent, and both miniaturization and low inductance can be achieved.

  The sheet-like glass fiber substrate constituting the prepreg is a woven fabric or a nonwoven fabric made of glass fibers. In order to increase the strength of the insulating plate and suppress deformation during injection molding, a glass fiber woven fabric is preferable.

The insulating plate is held in the mold as an insert part when the resin molded product is molded in a high-temperature mold. At this time, the glass transition temperature is preferably 150 ° C. or higher in order to ensure the strength against pressure of the resin that is injection-molded in a high temperature state. Thereby, the deformation | transformation at the time of injection molding can be suppressed.
In order to increase the glass transition temperature, it is necessary to increase the crosslinking density of the epoxy resin, and it is preferable to use not only a bifunctional epoxy resin but also a polyfunctional epoxy resin. The polyfunctional epoxy resin may be, for example, a trifunctional epoxy compound having 3 to 4 functional orthocresol novolac type epoxy compound, a trifunctional epoxy compound obtained by glycidylating a triphenylolmethane compound, a tetrafunctional epoxy using tetraphenylolethane or diaminodiphenylmethane as a raw material. Compounds, etc., and these compounds may be used alone or in combination. Here, the glass transition temperature is a value obtained by measuring the planar direction of the insulating plate by the TMA method.

  In order to advance the curing reaction of the epoxy resin, a curing agent is blended. Examples of the curing agent include amine compounds and derivatives thereof, acid anhydrides, imidazoles and derivatives thereof, phenols or compounds and polymers thereof, and the like. Moreover, in order to accelerate | stimulate reaction of an epoxy resin monomer and a hardening | curing agent, a hardening accelerator can be used. Examples of the curing accelerator include triphenylphosphine, imidazole and derivatives thereof, tertiary amine compounds and derivatives thereof, and the like.

  The inorganic filler compounded in the epoxy resin composition blended with the curing agent or curing accelerator is a metal oxide, hydroxide, inorganic ceramic, or other filler, such as boron nitride, aluminum nitride, silicon nitride. Inorganic powder fillers such as silicon carbide, titanium nitride, zinc oxide, tungsten carbide, alumina, and magnesium oxide, and fibrous fillers such as synthetic fibers and ceramic fibers. Two or more of these inorganic fillers may be used in combination.

  If an inorganic filler with a high relative dielectric constant is used and the relative dielectric constant of the insulating plate is 7 or more, the capacitance between the first DC wiring electrode plate and the second DC wiring electrode plate increases, and the semiconductor This is preferable because a surge voltage due to switching of elements can be reduced. Among these, it is preferable to use barium titanate having a very high relative dielectric constant, and the content is preferably 30% by mass or more.

  The insulating plate is prepared by diluting the above epoxy resin composition in a solvent as necessary to prepare a varnish, impregnating the varnish into a sheet-like glass fiber substrate, drying by heating and preparing a semi-cured state. And this is heat-press-molded to make an insulating plate.

  Examples of the present invention will be described below, and the present invention will be described in detail. In the following examples and comparative examples, “part” means “part by mass”. Moreover, this invention is not limited to a present Example, unless it deviates from the summary.

The material specifications used in this example are as follows.
(A) Prepreg a: 100 parts of an epoxy resin having a biphenyl skeleton as epoxy resin (Japan Epoxy Resin “YL6121H”, epoxy equivalent 175) is prepared, and this is added to 100 parts of methyl isobutyl ketone (Wako Pure Chemical Industries) at 100 ° C. And dissolved at room temperature. As a curing agent, 69 parts of an acid anhydride curing agent (“YH306” manufactured by Japan Epoxy Resin, equivalent of 120) was prepared, and this was dissolved in 100 parts of methyl isobutyl ketone (manufactured by Wako Pure Chemical Industries) at 100 ° C. and returned to room temperature. .
The above epoxy resin solution and curing agent solution were mixed and stirred to prepare a uniform epoxy resin varnish a. The epoxy resin varnish a was impregnated into a 60 μm thick glass fiber woven fabric and dried by heating to prepare a prepreg a having a thickness of 100 μm.
(B) Prepreg b: 100 parts of an epoxy resin having a biphenyl skeleton as an epoxy resin (“YL6121H” manufactured by Japan Epoxy Resin, epoxy equivalent of 175) is prepared, and this is added to 100 parts of methyl isobutyl ketone (manufactured by Wako Pure Chemical Industries) at 100 ° C. And dissolved at room temperature. As a curing agent, 74 parts of a phenol novolac curing agent (“LF-6161” manufactured by DIC, OH equivalent 130) is prepared, dissolved in 100 parts of methyl isobutyl ketone (manufactured by Wako Pure Chemical Industries) at 100 ° C., and returned to room temperature. It was.
The above epoxy resin solution and curing agent solution were mixed and stirred to prepare a uniform epoxy resin varnish b. The epoxy resin varnish b was impregnated into a 60 μm thick glass fiber woven fabric and dried by heating to prepare a prepreg b having a thickness of 100 μm.
(C) Prepreg c; 40 parts of titanium dioxide (“R-820” manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.3 μm, relative dielectric constant 100) as an inorganic filler is added to the epoxy resin varnish b and kneaded. An epoxy resin varnish c was prepared. The epoxy resin varnish c was impregnated into a 60 μm thick glass fiber woven fabric and dried by heating to prepare a prepreg b having a thickness of 100 μm.
(D) prepreg d; 30 parts of barium titanate (“BT-SA” manufactured by Kyoritsu Material, average particle diameter: 2 μm, relative dielectric constant 1200) as an inorganic filler is added to the epoxy resin varnish b and kneaded. Epoxy resin varnish d was prepared. The epoxy resin varnish d was impregnated into a 60 μm thick glass fiber woven fabric and dried by heating to prepare a prepreg d having a thickness of 100 μm.

Example 1
Ten prepregs a were stacked and integrated by heating and pressing for 90 minutes under conditions of a temperature of 175 ° C. and a pressure of 6 MPa to obtain an insulating plate having a thickness of 1.0 mm. The insulating plate was shaped by an NC router so as to match the shape of the DC wiring electrode plate. The shaped insulating plate was sized to protrude 1 mm from the edge of the DC wiring electrode plate. The insulating plate had a glass transition temperature of 120 ° C. and a relative dielectric constant of 5.
A copper bus bar (C1100) having a thickness of 2 mm is disposed as a first DC wiring electrode plate and a second DC wiring electrode plate on both sides of the insulating plate (see FIG. 2). A resin molded body having a first DC wiring electrode plate and a second DC wiring electrode plate as insert parts, which is inserted into a mold at 150 ° C., injection-molded with a PPS resin melted under an injection pressure of 20 MPa. Got.

The results of measuring the dielectric breakdown voltage, deformation due to molding, inductance, and capacitance of the resin molded body obtained in Example 1 are shown in Table 1 together with the configuration of the resin molded body. The measurement is based on the method shown below.
Glass transition temperature: A plate-shaped sample of 5 × 10 mm was cut out from the insulating plate, and the glass transition temperature in the plane direction in the range of 30 ° C. to 260 ° C. was measured by TMA measurement.
Relative permittivity: The relative permittivity of the insulating plate was measured according to JIS-K6911.
Dielectric breakdown voltage: Increase the voltage after bringing the probe of the withstand voltage tester into contact with the fastening terminals of the first DC wiring electrode plate and the second DC wiring electrode plate. It was measured.
Deformation by molding: After cutting the resin molded body, the bending angle of the insulating plate inside the resin molded body is visually observed. If the folding angle is less than 10 °, “◯”, if it is 10 ° or more and less than 45 ° If “Δ”, 45 ° or more, “x” was assigned. The bending angle was measured from the reference (the folding angle 0 °) based on the linear shape of the insulating plate before forming.
Inductance: The ends of the first DC wiring electrode plate and the second DC wiring electrode plate shown in FIG. 1 that have no fastening terminals are connected to each other with an aluminum wire (0.5 mmφ) to form a short-circuit current circuit. Then, after bringing the probe of the LCR meter into contact with the fastening terminal, the inductance generated when a frequency of 1 kHz and an alternating current of 20 mA were applied was measured.
Capacitance: The capacitance when an alternating current having a frequency of 1 kHz was applied after the probe of the LCR meter was brought into contact with the fastening terminals of the first DC wiring electrode plate and the second DC wiring electrode plate was measured.

Example 2
In Example 1, a resin molded body was obtained in the same manner as in Example 1, except that an insulating plate having a thickness of 0.3 mm, in which three prepregs a were stacked, was used. At this time, the glass transition temperature of the insulating plate was 120 ° C., and the relative dielectric constant was 5.

Example 3
In Example 2, a resin molded body was obtained in the same manner as in Example 2 except that an insulating plate having a thickness of 0.3 mm, in which three prepregs b were stacked, was used. At this time, the insulating plate had a glass transition temperature of 150 ° C. and a relative dielectric constant of 5.

Example 4
In Example 2, a resin molded body was obtained in the same manner as in Example 2, except that an insulating plate having a thickness of 0.3 mm, in which three prepregs c were stacked, was used. At this time, the glass transition temperature of the insulating plate was 150 ° C., and the relative dielectric constant was 7.

Example 5
In Example 2, a resin molded body was obtained in the same manner as in Example 2, except that an insulating plate having a thickness of 0.3 mm, in which three prepregs d were stacked, was used. At this time, the glass transition temperature of the insulating plate was 150 ° C., and the relative dielectric constant was 7.

Example 6
One sheet of prepreg b was used and integrated by heating and pressing for 90 minutes under the conditions of a temperature of 175 ° C. and a pressure of 6 MPa to obtain an insulating plate having a thickness of 0.1 mm. The insulating plate was shaped with an NC router so as to match the shape of the DC wiring electrode plate. The shaped insulating plate was sized to protrude 1 mm from the edge of the DC wiring electrode plate. The insulating plate had a glass transition temperature of 150 ° C. and a relative dielectric constant of 5.
Using the above three insulating plates, a copper bus bar (C1100) having a thickness of 2 mm is arranged as a first DC wiring electrode plate and a second DC wiring electrode plate on both sides thereof (see FIG. 3), and the mold temperature A resin molded body having a first DC wiring electrode plate and a second DC wiring electrode plate as insert parts, which is inserted into a mold at 150 ° C., injection-molded with a PPS resin melted under an injection pressure of 20 MPa. Got. The shape of the DC wiring electrode plate at this time has a bent portion as shown in FIG. 3, but the insulating plate is flexible, and the insulating plate is bent to the bent shape of the DC wiring electrode plate. I was able to follow.

Comparative Example 1
In Example 1, a resin molded body was obtained in the same manner as in Example 1 except that 15 prepregs a were stacked and an insulating plate having a thickness of 1.5 mm was used. At this time, the glass transition temperature of the insulating plate was 120 ° C., and the relative dielectric constant was 5.

Comparative Example 2
In Example 1, a resin molded body was obtained in the same manner as in Example 1 except that an insulating plate having a thickness of 0.1 mm using one prepreg a was used. At this time, the glass transition temperature of the insulating plate was 120 ° C., and the relative dielectric constant was 5.

Comparative Example 3
Using PPS resin, a PPS plate (spacer) having the same shape as the insulating plate of Example 1 was produced by injection molding.
In Example 1, a resin molded body was obtained in the same manner as in Example 1 except that the PPS plate was used instead of the insulating plate. At this time, the glass transition temperature of the PPS plate was 80 ° C. and the relative dielectric constant was 4.

As is apparent from Table 1, the resin molded body according to the present invention has a first DC wiring electrode plate and a second DC wiring electrode plate stacked on one or more insulating plates. By arranging so that the plate surfaces are parallel and the total thickness of the insulating plate is 0.3 mm or more and 1 mm or less, it can be understood that there is little deformation due to molding, and the dielectric breakdown voltage and inductance are good. (Control of Examples 1 to 3 and Comparative Examples 1 to 3). In Comparative Example 1, since the total thickness of the insulating plates is thick, the inductance is large. In Comparative Example 2, since the total thickness of the insulating plates is thin, deformation due to molding is large, and the dielectric breakdown voltage is reduced. In Comparative Example 3, since the glass transition temperature of the PPS plate is low, deformation due to molding is large, and the dielectric breakdown voltage is reduced.

  Moreover, it can be understood that the capacitance between the first DC wiring electrode plate and the second DC wiring electrode plate is increased by setting the dielectric constant of the insulating plate to 7 or more (Examples 4 to 5 and the implementation). Control for Examples 2-3).

DESCRIPTION OF SYMBOLS 1 ... Resin molded object, 2 ... 1st DC wiring electrode plate, 3 ... 2nd DC wiring electrode plate, 4 ... Insulating plate

Claims (5)

A resin molded body having a first DC wiring electrode plate and a second DC wiring electrode plate as insert parts,
The first DC wiring electrode plate and the second DC wiring electrode plate are arranged so that the plate surfaces are parallel through one or two or more insulating plates stacked together,
The insulating plate is obtained by heat-pressing a prepreg obtained by impregnating and drying a thermosetting resin into a sheet-like glass fiber substrate.
The resin molded body, wherein a total thickness of the insulating plates is 0.3 mm or more and 1 mm or less.   The resin molding according to claim 1, wherein a glass transition temperature of the insulating plate is 150 ° C. or higher.   The resin molded body according to claim 1 or 2, wherein the insulating plate has a relative dielectric constant of 7 or more.   The resin molded body according to any one of claims 1 to 3, wherein the thermosetting resin is an epoxy resin containing barium titanate at 30% by mass or more.   5. The resin molded body according to claim 1, wherein the insulating plate has a thickness of 0.2 mm or less, and is a laminate of two or more.

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