JP5382090B2 - Insulation sheet and power module using the same - Google Patents

Description

  The present invention relates to an insulating sheet excellent in adhesiveness and thermal conductivity, and a power module using the insulating sheet.

  Conventionally, a heat conductive sheet is used as a heat conductive material that is adhered to a heat generating element such as an electric / electronic component and transfers heat from the heat generating element to a heat sink member to dissipate the heat, and has a heat conductivity of 10 W / mK or more. For example, there is one in which a pressure-sensitive adhesive layer containing a thermally conductive filler and capable of sticking at room temperature is laminated on at least one surface of a metal sheet such as copper or aluminum or a graphite sheet (see, for example, Patent Document 1).

JP 2002-194306 A (first page)

  However, since the heat conductive sheet is composed of a plurality of layers of a sheet-like material such as a metal sheet or a graphite sheet and an adhesive layer, between the sheet-like material and the adhesive layer, the metal or the surface of the graphite and the organic layer of the adhesive layer There is an interface with the component, and there is a problem that the adhesive strength of the heat conductive sheet is lowered at this interface, and the heat conductivity and the insulation performance are lowered.

  The present invention has been made to solve such a problem, and an object of the present invention is to obtain an insulating sheet excellent in thermal conductivity and insulation, in which a decrease in adhesive force is prevented. Moreover, it aims at obtaining the power module using this insulation sheet.

  The insulating sheet according to the present invention includes an inner region including a filling member in which a thermosetting resin, a flat filler, and a particulate filler are mixed, and at least one surface of the inner region has a smaller filling rate than the inner region. An adhesive surface region containing an insulating filler is provided, and the filling rate increases from the adhesive surface region toward the internal region in a stepwise or inclined manner to form a continuous layer body, and The insulating filler in the bonding surface region is only a flat filler.

  According to the present invention, it is possible to prevent the adhesive force from being lowered, to have excellent thermal conductivity, and to increase the insulation performance such as a dielectric breakdown electric field.

It is explanatory drawing of the insulating sheet of Embodiment 1 of this invention. It is a characteristic view which shows the change of the specific adhesive strength by the heat conductivity regarding the insulating sheet of Embodiment 1 of this invention. It is a characteristic view which shows the change of the dielectric breakdown electric field by the thermal conductivity regarding the insulating sheet of Embodiment 1 of this invention. It is explanatory drawing which showed typically the insulating sheet of Embodiment 2 of this invention. It is explanatory drawing which showed typically another insulating sheet of Embodiment 2 of this invention. It is explanatory drawing which showed typically the filling state of the filler concerning the insulating sheet of Embodiment 3 of this invention. It is explanatory drawing which shows typically the insulating sheet of Embodiment 4 of this invention. It is explanatory drawing which shows typically the insulating sheet of Embodiment 5 of this invention. It is explanatory drawing of the lamination process in the manufacturing method of the insulating sheet of Embodiment 6 of this invention. It is explanatory drawing of the lamination process in the manufacturing method of the insulating sheet of Embodiment 7 of this invention. It is a block diagram of the power module of Embodiment 8 of this invention. It is a block diagram of the power module of Embodiment 8 of this invention. It is a block diagram of the power module of Embodiment 8 of this invention. It is a block diagram of the power module of Embodiment 9 of this invention.

Embodiment 1 FIG.
FIG. 1 is an explanatory diagram of an insulating sheet according to Embodiment 1 of the present invention, and is a case where it is used for bonding a lead frame (conductive member) 2 on which a power semiconductor element 1 is mounted and a heat sink member 6. The insulating sheet 7 according to the present embodiment is configured by dispersing a filling member in an adhesive component mainly composed of a thermosetting resin such as an epoxy resin, and the filling member is uniform in the adhesive component. The insulating sheet 7 is mainly dispersed in the region contributing to the adhesion between the lead frame (conductive member) 2 and the heat sink member 6 (in the region extending from the bonding surface 7a of the insulating sheet 7 to the inside of the insulating sheet). This region is referred to as an adhesive surface region 7b. In a sheet made of a thermosetting resin, a thickness of 0.1 to 1000 μm corresponds to this region from the adhesive surface), and a region other than the adhesive surface region (this region is referred to as this region). In the case of the inner region 7c), the filling rate of the filling member in the bonding surface region 7b is set to a range that is smaller than the filling rate in the inner region 7c and prevents a decrease in adhesive force. That by a range exhibiting excellent thermal conductivity the filling factor of the filling member, it is possible to obtain adhesion, the insulating sheet having excellent thermal conductivity and insulating properties.

  As the power module increases in current and speed, the power semiconductor element generates more heat. On the other hand, the power module is required to be smaller and more productive. Although it is desirable to use a metal with high thermal conductivity, it is necessary to insulate the conductive member and the heat sink member, which are electrically connected to the power semiconductor element, and are interposed between the conductive member and the heat sink member. Therefore, an insulating sheet that is excellent in properties and thermal conductivity and excellent in adhesion between the conductive member and the heat sink member is required.

FIG. 2 is a characteristic diagram showing a change in specific adhesive strength due to thermal conductivity related to the insulating sheet of the present embodiment.
In order to change the thermal conductivity of the insulating sheet, the filling amount of the filling member in the insulating sheet is adjusted. An insulating sheet having a predetermined thermal conductivity is formed on, for example, a copper base, and the adhesive strength between the insulating sheet and the copper base is measured, but the adhesive strength between the insulating sheet and the copper base includes a filling member. It shows as a specific adhesive strength with the adhesive strength of an insulating sheet (thermal conductivity is 0.2 w / mK) using only the adhesive component not to be 100%.
As can be seen from FIG. 2, the thermal conductivity increases as the filling amount of the filling member increases, but when the filling amount increases and the thermal conductivity exceeds 8 W / mK, the interface between the filling member and the organic component of the adhesive component. As the number of defects increases and defects such as voids increase, the adhesive force starts to decrease, and when it reaches 10 W / mK or more, the adhesive force decreases rapidly.
FIG. 3 is a characteristic diagram showing the change in the dielectric breakdown electric field of the insulating sheet having a thickness of 1 mm whose thermal conductivity is changed as described above, depending on the thermal conductivity. As shown in FIG. The thermal conductivity increases when the added amount of the member increases, but when the filling amount increases and the thermal conductivity exceeds 15 W / mK, the interface between the filled member and the organic component of the adhesive component increases, and voids and the like increase. As the number of defects increases, the breakdown electric field starts to decrease, and it can be seen that the breakdown electric field rapidly decreases at 16 W / mK or more.

Therefore, as can be seen from FIGS. 2 and 3, for example, when a sheet having a high thermal conductivity of 10 W / mK or more is obtained by uniformly filling the adhesive component with the filling member, the breakdown electric field is sufficient. However, the adhesive strength decreases. Moreover, when it is going to obtain sufficient adhesive strength and a fracture | rupture electric field with what was filled with the filling member uniformly, thermal conductivity will be significantly less than 10 W / mK.
From the above, in order to obtain a sheet having high adhesiveness, excellent insulating performance, and high thermal conductivity of about 10 W / mK or more compared to the conventional one, the function of mainly adhering to a conductive member or a heat sink member is provided. The surface area (adhesion surface area) has a thermal conductivity of 10 W / mK or less, preferably 8 W / mK or less, and a composition that increases the adhesive strength, and the internal area other than the adhesion surface area is 10 to 16 W. Compared to the case where the insulating sheet is made of a composition having a uniform filling rate by making the composition having a high thermal conductivity of / mK and making the thermal conductivity of the bonding surface region smaller than the thermal conductivity of the inner region. In addition, it is possible to satisfy both adhesiveness, insulating properties and thermal conductivity properties.
In addition, the filling member related to the insulating sheet of the present embodiment is filled, for example, so that the filling rate in the insulating sheet is inclined so that the filling rate gradually increases as the distance from the adhesive surface to the inside of the sheet increases. Then, the thermal conductivity is gradually increased as the distance from the adhesive surface of the insulating sheet is increased in the inner direction, or the filling ratio of the filling member is changed stepwise in the adhesive surface region 7b and the inner region 7c. Then, the thermal conductivity in the bonding surface region of the insulating sheet and the thermal conductivity of the inner region other than the bonding surface region of the insulating sheet are made to differ stepwise.

As the filling member related to the insulating sheet of the present embodiment, a flat or particulate filler, or a sheet having a through hole is used.
A flat filler is a filler having a flat shape like a three-dimensional object being crushed, and has a thin rectangular shape with a long side and a short side, and the cross section is not limited to a square. Other polygons may be oval with some rounded corners. Further, it may be a regular square, a regular polygon, or a circle having the same long side and short side. It may be produced by crushing in the manufacturing process, or may have an original shape, such as aluminum oxide (alumina), boron nitride, silicon carbide, mica, etc., and two or more of these may be used.
The particulate filler is preferably substantially spherical, but may be a pulverized shape and a polyhedral shape. As a material, aluminum oxide (alumina), silicon oxide (silica), silicon nitride, aluminum nitride, silicon carbide, boron nitride, or the like may be used.
Further, the particulate filler may be agglomerated of the flat filler or the particulate filler.
As a sheet having a through-hole, a conductive metal sheet having a through-hole, a ceramic sheet having a through-hole, a ceramic sheet having a through-hole and coated with a metal, or a through-hole having the above-described through-hole A glass laminated plate in which holes are coated with metal is used, and the adhesive component is continuous in the insulating sheet by the through-holes, and peeling or the like due to continuous interfaces can be prevented. It should be noted that a conductive filling member such as a metal sheet having a through-hole is more stable in insulation when used in an inner region, especially in a core region that is a central region in the thickness direction of the inner region than in an adhesive surface region. preferable.

As the thermosetting resin which is the main component of the adhesive component relating to the insulating sheet of the present embodiment, for example, an epoxy resin can be used, specifically, a liquid bisphenol A type epoxy resin {trade name: Epicoat 828, Japan Epoxy Co., Ltd.}, Liquid bisphenol F type epoxy resin {Product name: Epicoat 807, Japan Epoxy Co., Ltd.}, Solid bisphenol A type epoxy resin {Product name: Epicoat 1001, made by Japan Epoxy Co., Ltd.}, Ortho-cresol novolac type epoxy resin {trade name: EOCN-102S, manufactured by Nippon Kayaku Co., Ltd.}, phenol novolac type epoxy resin {trade name: Epicoat 152, manufactured by Japan Epoxy Co., Ltd.}, alicyclic aliphatic epoxy resin {Product name: CY179, manufactured by Bantico Co., Ltd.} Nord type epoxy resin {trade name: ELM100, manufactured by Sumitomo Chemical Co., Ltd.}, special multifunctional epoxy resin {trade name: EPPN501, manufactured by Nippon Kayaku Co., Ltd.}, and two or more of these are used in combination. Also good.
In addition, as curing agents, alicyclic acid anhydrides such as methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and hymic anhydride, aliphatic acid anhydrides such as dodecenyl succinic anhydride, phthalic anhydride, and trimellitic anhydride Aromatic acid anhydrides such as acids, organic dihydrazides such as dicyandiamide and adipic acid dihydrazide, tris (dimethylaminomethyl) phenol, dimethylbenzylamine, 1,8-diazabicyclo (5,4,0) undecene, and derivatives thereof; -It can be made into a solid sheet using imidazoles such as methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, etc., and two or more of these may be used in combination.
Moreover, you may use suitably organic solvents, such as acetone and toluene, as a viscosity modifier.

Embodiment 2. FIG.
FIG. 4 is an explanatory view schematically showing the insulating sheet 7 according to the second embodiment of the present invention, in which a filling member composed of a flat filler 71 and a particulate filler 72 is dispersed in an adhesive component 70. Since the insulating sheet 7 has the adhesive surfaces 7a on both sides, the upper and lower surface regions of the insulating sheet 7 become the adhesive surface region 7b, and the filling rate of the filling member in the adhesive surface region 7b is the filling rate in the internal region 7c. The filling rate of the filling member is adjusted so that the thermal conductivity of the bonding surface region 7b and the internal region 7c is within the range shown in the first embodiment.
In FIG. 4A, the filling rate of the filling member is filled so as to increase successively as it moves away from the bonding surface of the insulating sheet in the internal direction (center portion).
FIG. 4B shows the thermal conductivity of the bonding surface region 7b and the inner region 7c by adjusting the filling rate with respect to the total volume of the filling member composed of the flat filler 71 and the particulate filler 72 of the filling member. With the structure changed stepwise, the filling rate of the filling member in the bonding surface region 7b is smaller than that of the inner region 7c, and the thermal conductivity of the bonding surface region 7b and the inner region 7c is shown in the first embodiment. The range.
With the above configuration, the insulating sheet 7 of the present embodiment is maintained in adhesiveness by the adhesive surface region 7b with sufficient thermosetting resin component, and can secure thermal conductivity in the internal region 7c. Therefore, it is possible to obtain an insulating sheet having both adhesiveness and high thermal conductivity, rather than using an insulating sheet whose adhesiveness and insulating performance are significantly reduced by high filling with a filling member in order to obtain high thermal conductivity. Can do.
FIG. 5 is an explanatory view schematically showing another insulating sheet 7 according to Embodiment 2 of the present invention, in which the adhesive surface 7a is provided on only one surface of the insulating sheet 7, and the adhesive surface side is the adhesive surface region. 7b, the other surface side is an internal region 7c, and is suitably used as a sheet structure that requires adhesiveness only on one surface.

Embodiment 3 FIG.
FIG. 6 is an explanatory view schematically showing a filling state of the filling member related to the insulating sheet according to the third embodiment of the present invention, in which the arrow indicates the thickness direction of the insulating sheet, and (a) is the filling member. When the flat filler 71 and the particulate filler 72 coexist, (b) is the case where only the flat filler 71 is used.
That is, the insulating sheet of the present embodiment uses both the flat filler 71 and the particulate filler 72 in the first embodiment {FIG. 6 (a)} or uses only the flat filler 71 {FIG. (B)} Others are the same as in the first embodiment, and when the flat filler 71 and the particulate filler 72 are used together, in the insulating sheet, the particulate filler supports the flat filler, and the insulating sheet In the thickness direction, the flat filler is oriented in the long side direction. Accordingly, the heat dissipation characteristics in the thickness direction are remarkably improved and the overlap of the flat fillers is reduced, so that the filling amount can be increased.
Further, when only the flat filler 71 is used as shown in (b), since the flat filler is overlapped and oriented in the insulating sheet, the insulation performance such as a dielectric breakdown electric field can be increased.

Embodiment 4 FIG.
FIG. 7 is an explanatory view schematically showing the insulating sheet 7 according to the fourth embodiment of the present invention, and FIG. 7A shows that the thermal conductivity is in the range of the adhesive surface area in the first embodiment. In the insulating sheet in which the adhesive components 70 are uniformly filled with the fillers 71 and 72, the inner region 7c has a through hole 74 as a filling member in the core region which is a central region in the thickness direction. FIG. 7B shows a structure in which the excellent metal sheet 73 is arranged. FIG. 7B shows a structure in which the metal sheet 73 is provided as a filling member in the central portion (core region) of the inner region 7c of the insulating sheet of the second embodiment. The conductive filling member such as the metal sheet 73 is more preferably used in the inner region, particularly in the core region, than in the bonding surface region, in terms of insulation stability. In the present embodiment, since the resin is continuous in the through hole of the metal sheet 73, the interface between the metal sheet and the thermosetting resin in the insulating sheet is not continuous, and peeling at the interface can be prevented. .
In addition, in the adhesion | attachment using the insulating sheet 7 of the said Embodiment 1-4, in order to improve adhesive strength further, you may contain a coupling agent in an adhesive agent component.
Examples of coupling agents include γ-glycidoxypropyltrimethoxysilane, N-Β (aminoethyl) γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxy. There are silanes. Two or more of the above coupling agents may be used in combination.

Embodiment 5 FIG.
FIG. 8 is an explanatory view schematically showing the insulating sheet 7 according to the fifth embodiment of the present invention. In the inner region 7c of the insulating sheet according to the second embodiment, a filling member is provided in the core region in the central region in the thickness direction. As described above, an insulating plate 76 such as a glass laminated plate having a through-hole 74 and coated with a metal layer 75 such as copper is disposed on the surface of the through-hole, and is thermally conducted by the copper 75 coated on the through-hole. Since the resin is continuous in the through hole, the interface is not continuous, and peeling at the interface can be prevented. In addition, by using the said insulating plate, the stress received at the time of hardening in the preparation process of an insulating sheet and the shrinkage | contraction of resin can be prevented as shown below.

Embodiment 6 FIG.
FIG. 9 is an explanatory diagram of a laminating process in the method for manufacturing an insulating sheet according to the embodiment of the present invention, and arrows indicate the laminating direction.
That is, on the base material 21 such as copper, the first layer 17b made of the first insulating sheet composition serving as the adhesive surface region, and the second layer made of the second insulating sheet composition serving as the inner region. 17c, the first layer 17b made of the first insulating sheet composition to be the bonding surface region is formed to obtain the laminate 7e in the A or B stage state {FIG. 9 (a)}.
In addition, a first layer 17b made of a first insulating sheet composition serving as an adhesive surface region and a second layer 17c made of a second insulating sheet composition serving as an internal region are sequentially formed on the substrate 21. Two pieces formed are bonded together to obtain a laminate 7e in the A or B stage state (FIG. 9B).
Moreover, what formed the 1st layer 17b which consists of the 1st insulating sheet composition used as the adhesion surface area | region on the said base material 21 becomes the 2nd layer 17c which consists of the 2nd insulating sheet composition used as an internal area | region. To obtain a laminate 7e in the A or B stage state (FIG. 9C).
In addition, the filling rate of the filling member in the first insulating sheet composition serving as the adhesive surface region is smaller than the filling rate of the filling member in the second insulating sheet composition serving as the internal region, and each insulating sheet composition The thermal conductivity is in the range of the thermal conductivity shown in the first embodiment by thermosetting.
When the laminate 7e having the adhesive component A or B stage obtained as described above is pressed, the first layer 17b made of the first insulating sheet composition that becomes the bonding surface region and the inner region are formed. The resin of the second layer 17c made of the second insulating sheet composition is mixed with each other to obtain the insulating sheet of the present embodiment in which the interface disappears and the entire insulating sheet becomes a continuous layer. As a result, air with low thermal conductivity is pushed out and porous defects are eliminated, so that heat is efficiently transferred and heat conductivity is increased, and voids such as voids that are defects in insulation characteristics are also improved. There is an effect that the insulation performance can be improved by suppressing the generation of corona.

Embodiment 7 FIG.
FIG. 10 is an explanatory diagram of a laminating process in the method for manufacturing an insulating sheet according to the seventh embodiment of the present invention, and arrows in the figure indicate the laminating direction.
That is, two sheets of an insulating sheet composition in which a filling member is dispersed in an adhesive component are prepared on a release film, and the difference in the settling speed of the filling member is used due to the difference in specific gravity of the filling member in the above-mentioned application state. Then, after adjusting the distribution of the filling member so that the adhesive surface region 7b and the inner region 7c are within the range of the thermal conductivity shown in the first embodiment, the release film is removed, and this is filled toward the center. The laminated body 7e is obtained by laminating so as to increase the member concentration, and pressing is performed in the same manner as in the sixth embodiment, so that the resin of the insulating sheet composition is mixed with each other so that there is no interface and the entire insulating sheet becomes a continuous layer. The insulating sheet of the embodiment can be obtained.
By forming a sheet in this way, air with low thermal conductivity is pushed out and porous defects are eliminated, so heat is efficiently transferred and the thermal conductivity is increased, as well as voids that are defects in insulation characteristics, etc. There is a merit that the air gap is also improved, the generation of corona is suppressed, and the insulation performance can be improved.

Embodiment 8 FIG.
11, FIG. 12 and FIG. 13 are configuration diagrams of a power module according to an eighth embodiment of the present invention. The power semiconductor element 1 is mounted on a lead frame (conductive member) 2 and the above-described first to seventh embodiments. A hardened body 77 of insulating sheet is provided by adhering to the conductive member 2 and the heat sink member 6, and is connected to the control semiconductor element 4 separately mounted on the lead frame 2 by the metal wire 5. 10 is a sealed structure.
If the insulating sheet of the above embodiment is made into a semi-cured solid sheet in the A or B stage state and disposed between the lead frame 2 and the heat sink member 6 and cured by heating, the lead can be obtained with high productivity. The frame 2 and the heat sink member 6 can be bonded. The bonding process between the lead frame 2 and the heat sink member 6 by the curing reaction of the insulating sheet may be performed simultaneously in the sealing process with the mold resin 10.
As the mold resin 10 for sealing the power module, for example, a thermosetting resin such as an epoxy resin may be used. As the material of the lead frame 2, copper or aluminum metal is used. As the heat sink member 6, a metal such as copper or aluminum, an alloy thereof, or a ceramic such as alumina can be used.
In the power module according to the present embodiment, the insulating sheet cured body 77 for bonding the heat sink member 6 and the conductive member 2 has excellent thermal conductivity, adhesiveness, and insulation that are not found in conventional insulating heat conductive resin sheets. Therefore, it is possible to reduce the size and increase the capacity of the power module.
As shown in FIG. 12, when the insulating sheet cured body 77 covers an insulating plate such as a metal heat sink member or alumina, the difference in thermal expansion coefficient from the mold resin 10 can be reduced, so that peeling can be prevented.
Moreover, since the said insulating sheet can achieve high heat conductivity, it can also show a favorable heat dissipation characteristic also as the heat sink member 6, and as shown in FIG. 13, the hardening body 77 of the insulating sheet 7 shown in FIG. It is also possible to make a single layer structure that also serves as a member, and the difference in thermal expansion coefficient from the mold resin 10 can be reduced. For this reason, generation | occurrence | production of a crack etc. can be suppressed more.

Embodiment 9 FIG.
FIG. 14 is a configuration diagram of a power module according to the ninth embodiment of the present invention, which is a case type power module.
That is, the heat sink member 6, the circuit board 8 provided on the surface of the heat sink member 6, the power semiconductor element 1 mounted on the circuit board 8, the case 9 bonded to the peripheral portion of the heat sink member 6, the case The first embodiment is bonded to the casting resin 4 injected into the sealing member 4 for sealing the circuit board 8 and the power semiconductor element 1 and the opposite surface of the heat sink member 6 opposite to the surface on which the circuit board 8 is provided. The hardened body 77 of the insulating sheet of 7 to 7 is provided, and the heat sink member 6 and the heat spreader 11 are bonded by the hardened body 77.
In the power module according to the present embodiment, the cured sheet 77 of the insulating sheet that bonds the heat sink member 6 and the heat spreader 11 has excellent thermal conductivity, adhesiveness, and insulation that are not found in conventional insulating thermal conductive resin sheets. Therefore, it is possible to reduce the size and increase the capacity of the power module.

Example 1.
As shown in Table 1, bisphenol A type epoxy resin {product name: Epicoat 828, manufactured by Japan Epoxy Resin Co., Ltd.} 100 parts by weight and curing accelerator 1-cyanoethyl-2-methylimidazole {product name: Curesol 2PN-CN , Shikoku Kasei Kogyo Co., Ltd.} 200 parts by weight of methyl ethyl ketone is added to an adhesive component consisting of 1 part by weight, and then boron nitride is 7 μm as a flat filler (trade name: GP, manufactured by Denki Kagaku Kogyo Co., Ltd.) 143 parts by weight, silicon filler 5 μm as a particulate filler {trade name: SN-7, manufactured by Denki Kagaku Kogyo Co., Ltd.} 201 parts by weight of a filling member is added and mixed and kneaded with three rolls To obtain an insulating sheet composition A.
In addition, in the insulating sheet composition A, the closing ratio of the filling member (filling member / insulating sheet) to the total volume of the adhesive component excluding methyl ethyl ketone and the filling member is 60% by volume. The volume ratio of boron nitride to silicon nitride is 1: 1.

The insulating sheet composition A was applied by a doctor blade method onto a release treatment surface of a polyethylene terephthalate sheet having a single-side release treatment with a thickness of 100 μm, and allowed to stand for 30 minutes to settle the filling member at 110 ° C. Heat-dried for 5 minutes, another polyethylene terephthalate sheet is provided on the surface of the insulating sheet material composition A coating film, and a B-stage laminate having a thickness of 55 μm is produced.
Next, two laminates in the above-mentioned B stage state were prepared, and the release treatment surface of each polyethylene terephthalate sheet was peeled off. As shown in FIG. 10, the peeled surfaces were put together at 130 ° C. with a pressure of 80 kgf / cm ² . The insulating sheet of the example of the present invention having a total thickness of about 200 μm was obtained by vacuum pressing, the thermal conductivity in the thickness direction of the insulating sheet was measured, and the results are shown in Table 2. The thermal conductivity was measured by a laser flash method.
Moreover, the insulating sheet produced in the same manner as described above was sandwiched between 2 mm thick copper plates to produce an adhesive test piece, and the tensile strength between the copper plate and the insulating sheet was measured at 50 mm / second. The breakdown electric field of the insulating sheet was also measured, and the results are shown in Table 2.

Example 2
The insulating sheet composition A shown in Table 1 and the insulating sheet composition B shown in Table 1 are prepared in the same manner as in Example 1. In addition, the volume ratio of boron nitride and silicon nitride in the insulating sheet composition B is 1: 1 like the insulating sheet composition A, and is based on the total volume of the adhesive component and the filling member excluding methyl ethyl ketone in the insulating sheet composition. By adjusting the closing ratio of the filling member (filling member / insulating sheet) as shown in Table 1, the thermal conductivity in the insulating sheet of this example obtained as follows is shown in the above embodiment. Can be adjusted within the range.
Insulating sheet composition B was applied onto the release-treated surface of a polyethylene terephthalate sheet having a single-sided release treatment with a thickness of 100 μm by a doctor blade method, heated and dried at 110 ° C. for 5 minutes, and an insulating sheet B layer (adhesive surface) A layer to be a region), and further, an insulating sheet composition A is applied thereon by a doctor blade method to laminate a 90 μm-thick insulating sheet A layer (layer to be an internal region) to form a B-stage laminate. Produced.
Next, two B-stage laminates were prepared, and the respective insulating sheet A layer surfaces were combined to obtain the laminate shown in FIG. 9B, which was vacuum pressed at 130 ° C. and a pressure of 80 kgf / cm ^2. Thus, an insulating sheet of an example of the present invention having a total thickness of about 210 μm was obtained.
The thermal conductivity of the obtained insulating sheet was evaluated in the same manner as in Example 1, and an adhesive test piece was prepared by sandwiching the insulating sheet prepared in the same manner as described above on a 2 mm thick copper plate, and the tensile strength was 50 mm / second. Was measured. The breakdown electric field of the insulating sheet was also measured, and the results are shown in Table 2.

Example 3
The insulating sheet composition A, the insulating sheet composition B, and the insulating sheet composition C shown in Table 1 were prepared. In addition, the volume ratio of boron nitride and silicon nitride in the insulating sheet composition C is 1: 1 as in the insulating sheet composition A, and is based on the total volume of the adhesive component and the filling member excluding methyl ethyl ketone in the insulating sheet composition. By adjusting the closing ratio of the filling member (filling member / insulating sheet) as shown in Table 1, the thermal conductivity in the insulating sheet of this example can be adjusted to the predetermined range shown in the above embodiment. it can.
First, the insulating sheet composition C was applied on the release treatment surface of a polyethylene terephthalate sheet having a single-sided release treatment with a thickness of 100 μm by a doctor blade method and dried by heating at 110 ° C. for 5 minutes. Got. Furthermore, the insulating sheet composition B was applied to the upper layer by a doctor blade method and heated and dried at 110 ° C. for 5 minutes to obtain an insulating sheet B layer having a thickness of 25 μm. Furthermore, the insulating sheet composition A was applied to the upper layer by a doctor blade method, dried by heating, and an insulating sheet A layer having a thickness of 85 μm was laminated to prepare a B-stage laminate.
Next, two laminates in the B-stage state were prepared, and the edge sheet A layer surfaces were combined and vacuum pressed at 130 ° C. to obtain an insulating sheet of an example of the present invention having a total thickness of 220 μm.
The thermal conductivity of the obtained insulating sheet was evaluated in the same manner as in Example 1. The insulating sheet produced in the same manner as described above was sandwiched between 2 mm thick copper plates to produce an adhesive test piece, and the tensile strength was 50 mm / second. Was measured. The breakdown electric field of the insulating sheet was also measured, and the results are shown in Table 2.

Example 4
An insulating sheet composition A and an insulating sheet composition B shown in Table 1 were prepared.
Next, the obtained insulating sheet composition B was coated on the release treated surface of a 100 μm thick single-sided polyethylene terephthalate sheet by the doctor blade method and dried by heating at 110 ° C. for 5 minutes, and further the insulating sheet composition was formed thereon. Product A was applied by a doctor blade method and dried by heating to obtain a B-stage laminate having the same thickness as in Example 2.
Next, two laminates in the above-mentioned B stage state were prepared, and vacuum-pressed at 130 ° C. with a 50 μm-thick copper sheet having through-holes having a diameter of 0.5 mm at intervals of 1 mm between each insulating sheet A layer surface. Then, an insulating sheet of an example of the present invention having a total thickness of 220 μm shown in the form of FIG.
The thermal conductivity of the obtained insulating sheet was evaluated in the same manner as in Example 1. An adhesive test piece was prepared by sandwiching an insulating sheet produced in the same manner as described above on a 2 mm thick copper plate, and the tensile strength was measured at 50 mm / second. Further, the breakdown electric field of the insulating sheet was also measured, and the results are shown in Table 2.

Example 5 FIG.
An insulating sheet composition A and an insulating sheet composition B shown in Table 1 were prepared.
Next, the obtained insulating sheet composition B was coated on the release treated surface of a 100 μm thick single-sided polyethylene terephthalate sheet by the doctor blade method and dried by heating at 110 ° C. for 5 minutes, and further the insulating sheet composition was formed thereon. Product A was applied by a doctor blade method and dried by heating to obtain a B-stage laminate having the same thickness as in Example 2.
Next, two B-stage laminates were prepared, and 100 μm-thick alumina sheets having through-holes having a diameter of 1 mm at intervals of 2 mm were sandwiched between the respective insulating sheet A layer surfaces and vacuum-pressed at 130 ° C. An insulating sheet of an example of the present invention having a thickness of 300 μm was produced.
The thermal conductivity of the obtained insulating sheet was evaluated in the same manner as in Example 1, and an adhesive test piece was prepared by sandwiching the insulating sheet prepared in the same manner as described above on a 2 mm thick copper plate, and the tensile strength was 50 mm / second. Was measured. The breakdown electric field of the insulating sheet was also measured. The results are shown in Table 2.

Example 6
An insulating sheet composition A and an insulating sheet composition B shown in Table 1 were prepared.
Next, the obtained insulating sheet composition B was coated on the release treated surface of a 100 μm thick single-sided polyethylene terephthalate sheet by the doctor blade method and dried by heating at 110 ° C. for 5 minutes, and further the insulating sheet composition was formed thereon. Product A was applied by a doctor blade method and dried by heating to obtain a B-stage laminate having the same thickness as in Example 2.
Then, two laminates in the B-stage state were prepared, and through holes having a diameter of 0.5 mm were provided at intervals of 2 mm between the respective insulating sheet A layer surfaces, and the surface of the through holes was coated with copper. An insulating sheet of an example of the present invention having a total thickness of about 1 mm shown in FIG. 8 was manufactured by vacuum pressing at 130 ° C. so as to sandwich an 8 mm thick glass laminate.
The thermal conductivity of the obtained insulating sheet was evaluated in the same manner as in Example 1, and an adhesive test piece was prepared by sandwiching the insulating sheet prepared in the same manner as described above on a 2 mm thick copper plate, and the tensile strength was 50 mm / second. Was measured. The breakdown electric field of the insulating sheet was also measured, and the results are shown in Table 2.

Comparative Example 1
Using the insulating sheet composition A shown in Table 1, a 200 μm thick thermally conductive adhesive film was produced.
The thermal conductivity was evaluated in the same manner as in Example 1 using the obtained heat conductive adhesive film. Further, an adhesive test piece was prepared by sandwiching a thermally conductive adhesive film prepared in the same manner as described above on a 2 mm thick copper plate, and the tensile strength was measured at 50 mm / second in the same manner as in Example 1. The breakdown electric field of the heat conductive adhesive film was also measured, and the results are shown in Table 2.

Comparative Example 2
Using the insulating sheet composition B shown in Table 1, a 200 μm thick thermally conductive adhesive film was produced.
The thermal conductivity was evaluated in the same manner as in Example 1 using the obtained heat conductive adhesive film. Further, an adhesive test piece was prepared by sandwiching a thermally conductive adhesive film prepared in the same manner as described above on a 2 mm thick copper plate, and the tensile strength was measured at 50 mm / second in the same manner as in Example 1. The breakdown electric field of the heat conductive adhesive film was also measured, and the results are shown in Table 2.

  From Table 2, it was shown that the insulating sheet of the Example of this invention is excellent in adhesive strength, and can effectively make heat conductivity and insulation compatible.

  DESCRIPTION OF SYMBOLS 1 Power semiconductor element, 2 Conductive member, 6 Heat sink member, 7 Insulation sheet, 7a Adhesive surface, 7b Adhesive surface area | region, 7c Internal area | region, 7e Laminated body, 17b 1st layer, 17c 2nd layer, 10 Mold resin, 70 Adhesive component, 71, 72 Filling member, 73 Metal sheet, 74 Through hole, 75 Metal layer, 76 Insulating plate, 77 Hardened body of insulating sheet, 8 Circuit board, 9 Case, 11 Heat spreader.

Claims (3)

An inner region having a filling member in which a thermosetting resin, a flat filler and a particulate filler are mixed, and an adhesive containing an insulating filler at a filling rate smaller than the inner region on at least one surface of the inner region A surface region is provided, and the filling rate increases stepwise or in an inclined manner from the adhesive surface region toward the internal region to form a continuous layer body, and an insulating filler in the adhesive surface region Is an insulating sheet characterized by comprising only a flat filler. The cured body of the insulating sheet according to claim 1, wherein the power semiconductor element, a conductive member on which the power semiconductor element is mounted, and a surface of the conductive member opposite to the surface on which the power semiconductor element is mounted are attached. A power module comprising a heat sink member attached to a cured body of the insulating sheet. A power semiconductor element; a circuit board on which the power semiconductor element is mounted; a heat sink member provided with the circuit board; a case bonded to a peripheral portion of the heat sink member; and the circuit board and the above injected into the case A cast resin for sealing the power semiconductor element, a cured body of the insulating sheet according to claim 1 attached to a surface of the heat sink member opposite to the surface on which the circuit board is provided, and the insulating sheet. A power module including a heat spreader attached to a cured body.

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