JP2020102554A - Laminate, electronic component, and inverter - Google Patents

Abstract

To provide a laminate having excellent insulating property and a heat dissipation property while having a good sheet property.SOLUTION: A laminate 10 includes a heat conductor 11 having a thermal conductivity of 10 W/m K or more, and an insulating resin layer 12 provided on a surface of the heat conductor 11 and containing a heat conductive filler. The relative permittivity of a surface 12X side of the insulating resin layer 12 on which the heat conductor 11 is provided is lower than the relative permittivity of a surface 12Y side of the insulating resin layer 12 opposite to the side on which the heat conductor 11 is provided, and a solvent content of the resin layer 12 is 50 ppm or more and 2000 ppm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electronic component, for example, a laminate used for a power semiconductor module.

Conventionally, power semiconductor modules have been used in industrial equipment such as inverters, elevators, and uninterruptible power supplies (UPS). A substrate used for a power semiconductor module is generally formed by laminating a ceramic substrate and a copper plate, but since these have different thermal expansion coefficients, there is a problem that peeling and warpage occur over time. Therefore, in recent years, development has been underway to replace the ceramic substrate with a resin sheet.

As such a resin sheet, for example, as shown in Patent Document 1, a first insulating layer that is a semi-cured product or a cured product, and an uncured product or a semi-cured product are provided on a heat conductor such as a copper plate. A laminated body is known in which a second insulating layer, which is an object, is provided in this order. Generally, a conductive layer such as a lead frame is attached on the substrate, but in the laminated body of Patent Document 1, the second insulating layer on the front surface side is an uncured product or a semi-cured product, and thus the conductive layer By further curing the laminated body to which is attached, the adhesion with the conductive layer can be enhanced.

In the laminated body of Patent Document 1, the first insulating layer contains an inorganic filler in an amount of 86% by weight or more and less than 97% by weight, and the second insulating layer contains an inorganic filler in an amount of 67% by weight or more and less than 95% by weight. Including, the content ratio of the inorganic filler in the first insulating layer is made higher than the content ratio of the inorganic filler in the second insulating layer. In Patent Document 1, by adjusting the content ratio in this manner, high heat dissipation is ensured while ensuring adhesion with the conductive layer.

Japanese Patent No. 5346363

In the use of power semiconductor modules, the density of semiconductor circuits is increasing, and it is required to further improve heat dissipation while ensuring the insulation of the resin sheet for substrates. In order to improve heat dissipation, it is conceivable to use an inorganic filler having high thermal conductivity or further increase the content of the inorganic filler. However, the inorganic filler having high thermal conductivity has anisotropy and is not well mixed with the resin, and if the content is increased, the insulating layer becomes brittle, and the sheet property of the laminate may be deteriorated. There is.
Then, this invention makes it a subject to provide the laminated body which was excellent in insulation and heat dissipation, while making sheet property favorable.

As a result of intensive studies, the present inventors have found that the above problems can be solved by adjusting the relative permittivity and the solvent content in the insulating resin layer, and have completed the present invention described below. That is, the present invention provides the following [1] to [12].
[1] A laminate comprising a heat conductor having a heat conductivity of 10 W/m·K or more and an insulating resin layer provided on the surface of the heat conductor and containing a heat conductive filler. ,
The relative dielectric constant of the surface of the insulating resin layer on which the heat conductor is provided is lower than the relative dielectric constant of the surface of the insulating resin layer opposite to the surface on which the heat conductor is provided,
A laminate, in which the solvent content of the insulating resin layer is 50 ppm or more and 2000 ppm or less.
[2] The laminated body according to the above [1], wherein the insulating resin layer has at least an uncured product or a semi-cured product in a region on a surface side opposite to a surface on which the heat conductor is provided.
[3] The laminate according to [2], wherein the insulating resin layer has at least a semi-cured product or a cured product in a region on the surface side on which the heat conductor is provided.
[4] The curing rate of the area on the surface side on which the heat conductor is provided is 50% or more,
The curing rate of the region on the side opposite to the side on which the heat conductor is provided is less than 80%,
Any one of the above-mentioned [1] to [3], wherein the curing rate of the region on the surface side on which the heat conductor is provided is higher than the curing rate of the region on the side opposite to the surface on which the heat conductor is provided. The laminate according to item.
[5] The thermally conductive filler contains boron nitride,
The said boron nitride is a laminated body any one of said [1]-[4] contained in the area|region by the side of the said insulating resin layer in which the heat conductor is provided.
[6] The heat conductive filler contains alumina,
The laminated body according to any one of the above [1] to [5], wherein the alumina is contained in a region of the insulating resin layer on the side opposite to the surface on which the heat conductor is provided.
[7] The laminate according to the above [6], wherein the alumina has an aspect ratio of 2 or less.
[8] The thermally conductive filler contains boron nitride,
The laminate according to the above [6] or [7], wherein boron nitride is further contained in a region of the insulating resin layer on the surface side opposite to the surface on which the heat conductor is provided.
[9] The thermally conductive filler contains boron nitride,
The area on the surface side on which the heat conductor is provided, and the area on the surface side opposite to the surface on which the heat conductor is provided both contain boron nitride,
In the insulating resin layer, the content rate of boron nitride in the surface side area where the heat conductor is provided is higher than the content rate of boron nitride in the surface side area opposite to the surface where the heat conductor is provided. The laminated body according to any one of [1] to [8].
[10] The laminate according to any one of the above [1] to [9], wherein the thickness of the heat conductor is 0.03 mm or more and 3 mm or less.
[11] An electronic component including the laminated body according to any one of [1] to [10].
[12] An inverter including the electronic component according to the above [11].

According to the present invention, it is possible to provide a laminate having excellent insulating properties and heat dissipation properties while having good sheet properties.

It is a typical sectional view showing a layered product of the present invention. It is a typical sectional view showing a layered product concerning one embodiment of the present invention.

Hereinafter, the present invention will be described using embodiments.
<Laminate>
The laminate 10 of the present invention includes a thermal conductor 11 having a thermal conductivity of 10 W/m·K or more, and an insulating resin layer 12 provided on the surface of the thermal conductor 11 and containing a thermally conductive filler. Equipped with. In the insulating resin layer 12, the relative permittivity on the surface on which the heat conductor 11 is provided (one surface 12X) is on the side opposite to the surface on which the heat conductor 11 is provided (the other surface 12Y). It is lower than the dielectric constant. Furthermore, the insulating resin layer 12 has a solvent content of 50 ppm or more and 2000 ppm or less.

The laminated body 10 is used for a semiconductor substrate or the like, and a conductive layer (not shown) such as a lead frame is formed on the other surface 12Y in a post process or the like. When a voltage is applied to the laminated body 10 on which the conductive layer is formed, if the relative dielectric constant on the other surface 12Y side of the insulating resin layer 12 is high, generally the end portion of the interface between the conductive layer and the insulating resin layer 12 is detected. Although dielectric breakdown may occur due to the concentration of the electric field, in the present invention, the concentration of the electric field is mitigated because the relative dielectric constant on the one surface 12X side of the insulating resin layer 12 is low. Thereby, dielectric breakdown is less likely to occur, and the insulating property of the laminated body 10 can be improved.

The insulating resin layer 12 contains a heat conductive filler, but in order to lower the relative dielectric constant on the one surface 12X side while increasing the heat conductivity, a filler having a high aspect ratio is used as the heat conductive filler. It is necessary to use or blend a large amount of heat conductive filler. Such a thermally conductive filler causes the insulating resin layer 12 to become brittle. In the present invention, the insulating resin layer 12 contains a small amount of the solvent as described above, so that even if a large amount of the thermally conductive filler is blended or a thermally conductive filler having a high aspect ratio is blended, the insulating resin is The layer 12 does not easily become brittle, and good sheet properties are maintained.

[Insulating resin layer]
(Solvent content)
The solvent content in the insulating resin layer 12 is 50 ppm or more and 2000 ppm or less as described above. When the solvent content is less than 50 ppm, the wettability of the insulating resin layer 12 is lost, the insulating resin layer 12 becomes brittle, and the sheet property of the laminate 10 deteriorates. Furthermore, the adhesion with the heat conductor 11 is also reduced. On the other hand, when it is more than 2000 ppm, the residual solvent in the insulating resin layer 12 lowers the adhesion to the heat conductor 11 and the insulating property of the insulating resin layer 12.
From the viewpoint of sheet properties, the solvent content of the insulating resin layer 12 is preferably 100 ppm or more, more preferably 150 ppm or more. Further, from the viewpoint of improving the adhesion to the heat conductor 11 and the insulating property of the insulating resin layer 12, the solvent content of the insulating resin layer 12 is preferably 1200 ppm or less, more preferably 800 ppm or less.
The solvent content of the insulating resin layer 12 can be measured by the method described in Examples described later.

The insulating resin layer 12 is formed by applying a resin composition diluted with a solvent and then drying the solvent used as the diluent, as described in the manufacturing method described later. In addition, in the production of the laminated body 10, generally, heating or the like is further performed by curing. Therefore, the solvent content of the insulating resin layer 12 may be adjusted by appropriately changing these drying conditions and curing conditions.

(Relative permittivity)
The insulating resin layer 12 may have a relative dielectric constant on the one surface 12X side lower than the relative dielectric constant on the other surface 12Y side, but the difference between these relative dielectric constants is preferably 2 or more. The above is more preferable. By setting the difference in relative permittivity to be equal to or more than the lower limit values, it becomes easy to secure the insulating property of the laminated body 10 by relaxing the electric field concentration.
The difference in relative dielectric constant is not particularly limited, but is 10 or less, preferably 7 or less from the viewpoint of practicality.

From the viewpoint of enhancing the insulating property, the relative permittivity on the one surface 12X side is, for example, 2 or more and 8 or less, preferably 3 or more and 7 or less, and more preferably 3 or more and 6 or less. The insulating resin layer 12 may have a relative permittivity of a region having a constant thickness from the one surface 12X side within the above range with respect to the total thickness of the insulating resin layer 12, and specifically, at least 10%. The relative permittivity of the region having a thickness of 10 is within the above range, and the relative permittivity of the region having a thickness of at least 20% is preferably within the above range.
The relative permittivity on the other surface 12Y side is, for example, 4 or more and 11 or less, preferably 5 or more and 10 or less, and more preferably 6 or more and 9 or less from the viewpoint of improving the insulating property. The insulating resin layer 12 may have a relative permittivity of a region having a constant thickness from the other surface 12Y side within the above range with respect to the total thickness of the insulating resin layer 12, and specifically, at least 10%. The relative permittivity of the region having a thickness of 10 is within the above range, and the relative permittivity of the region having a thickness of at least 20% is preferably within the above range.
In the present specification, the relative permittivity refers to the relative permittivity at a frequency of 1 MHz. The relative permittivity can be measured by the method described in Examples below.

(Curing characteristics)
In the insulating resin layer 12, it is preferable that the region on the other surface 12Y side is at least an uncured product or a semi-cured product. As described above, a conductive layer or the like is laminated on the other surface 12Y of the insulating resin layer 12 in a later step, but the region on the other surface 12Y side of the insulating resin layer 12 is an uncured product or a semi-cured product. Further, when the other surface 12Y side of the insulating resin layer 12 is cured after the conductive layers are laminated, the adhesiveness between the conductive layer and the insulating resin layer 12 is enhanced.

Further, it is more preferable that the region on the other surface 12Y side of the insulating resin layer 12 is at least an uncured product or a semi-cured product, and the region on the one surface 12X side is a semi-cured product or a cured product. When the region on the one surface 12X side is a semi-cured product or a cured product, the adhesion between the insulating resin layer 12 and the heat conductor 11 is enhanced. Further, by setting the region on the one surface 12X side as a semi-cured product or a cured product, various performances such as thermal conductivity and insulating property of the laminated body 10 can be stably ensured.

Here, that the region on the side of the other surface 12Y is at least an uncured product or a semi-cured product means that a region of a constant thickness from the other surface 12Y is an uncured product or a semi-cured product, Specifically, the curing rate of the region having the constant thickness may be less than 80%. By setting the curing rate to less than 80%, it becomes easy to enhance the adhesiveness to the conductive layer. Further, the curing rate is preferably less than 70%, more preferably less than 60%, and further preferably less than 50%.
Further, the curing rate of the region having a constant thickness from the other surface 12Y is preferably 1% or more, more preferably 5% or more, and further preferably 10% or more.
It should be noted that the insulating resin layer 12 may have a curing rate in a region having a constant thickness from the other surface 12Y within the above range with respect to the total thickness of the insulating resin layer 12, but specifically, at least 10%. It suffices that the curing rate of the region of thickness is within the above range, and the curing rate of the region of at least 20% is preferably within the above range.

Further, the region on the one surface 12X side being a semi-cured product or a cured product means that a region having a constant thickness from the one surface 12X is a semi-cured product or a cured product, and specifically, The hardening rate of the region having the constant thickness may be, for example, 50% or more. By setting the curing rate to 50% or more, the adhesion with the heat conductor 11 can be easily increased. Further, it becomes easy to improve the insulating property and the thermal conductivity of the laminated body 10. From these viewpoints, the curing rate is preferably 65% or more, more preferably 75% or more, further preferably 85% or more.
Further, the curing rate of the region having a constant thickness from the one surface 12X may be 100% or less, but may be 95% or less, for example.
It should be noted that the insulating resin layer 12 may have a curing rate in a region having a constant thickness from the one surface 12X within the above range with respect to the total thickness of the insulating resin layer 12, but specifically, at least 10%. It suffices that the curing rate of the region of thickness is within the above range, and it is preferable that the curing rate of at least 20% is within the above range.

The curing rate of the region on the one surface 12X side described above is typically higher than the curing rate of the region on the other surface 12Y side. Here, the curing rate of the region on the one surface 12X side is preferably 5% or more, more preferably 10% or more, more preferably 30% or more, higher than the curing rate of the other surface 12Y side region. More preferably, Further, the curing rate of the region on the one surface 12X side is preferably 100% or less, and preferably 90% or less, than the curing rate of the other surface 12Y side region. It is more preferable that the difference is less than or equal to %. By setting the difference in the curing rate within these ranges, it becomes easy to obtain good balance between the insulating property, the thermal conductivity, the adhesiveness with the thermal conductor 11, the adhesiveness with the conductive layer, and the like.
As described later, the above-mentioned curing rate can be adjusted by appropriately setting the curing conditions such as the curing temperature and the curing time of the first insulating layer and the second insulating layer 12B. It can also be adjusted by making the content of the thermosetting agent of the first insulating layer 12A larger than the content of the thermosetting agent of the second insulating layer 12B.

In a preferred embodiment, the insulating resin layer 12 includes a first insulating layer 12A and a second insulating layer 12B, as shown in FIG. As shown in FIG. 2, the first insulating layer 12A and the second insulating layer 12B are provided in this order on the surface of the heat conductor 11. In this case, the region having a constant thickness from the one surface 12X side described in the description of the relative permittivity and the curing rate is a region formed by the first insulating layer 12A. Further, the region having a constant thickness from the other surface 12Y side is a region formed by the second insulating layer 12B.
Therefore, the relative permittivity of the first insulating layer 12A becomes lower than the relative permittivity of the second insulating layer 12B, and the relative permittivity of the first insulating layer 12A and the relative permittivity of the second insulating layer 12B. The specific value of the coefficient is the same as the relative dielectric constant of the area on the side of one surface 12X and the relative dielectric constant of the area on the side of the other surface 12Y described above.

Further, in the insulating resin layer 12, the second insulating layer 12B is preferably an uncured product or a semi-cured product, and more preferably the second insulating layer 12B is an uncured product or a semi-cured product, and The insulating layer 12A is a semi-cured product or a cured product.
Then, the curing rate of the first insulating layer 12A, the curing rate of the second insulating layer 12B, and the specific value of the difference between these curing rates are the curing rate of the region on the one surface 12X side described above, It is as the hardening rate of the area|region by the side of the other surface 12Y, and the difference of these hardening rates.
In the present invention, by providing the two insulating layers 12A and 12B, it becomes possible to easily adjust the relative dielectric constant and the curing characteristics of the insulating resin layer 12 within the above-mentioned predetermined ranges.

(Thermally conductive filler)
The insulating resin layer 12 contains a heat conductive filler. Since the insulating resin layer 12 contains the thermally conductive filler, the thermal conductivity becomes high, and the heat dissipation of the laminated body 10 becomes good. The thermally conductive filler is an inorganic filler having a thermal conductivity of 10 W/m·K or more. Only one kind of the heat conductive filler may be used, but it is preferable to use two or more kinds in combination.
From the viewpoint of further increasing the thermal conductivity of the laminate 10, the thermal conductivity of the thermally conductive filler is preferably 15 W/m·K or more, more preferably 20 W/m·K or more. The upper limit of the thermal conductivity of the thermally conductive filler is not particularly limited, but an inorganic filler having a thermal conductivity of about 300 W/m·K is widely known, and a thermal conductivity of about 200 W/m·K. Inorganic fillers are readily available.

The thermally conductive filler is, for example, at least one selected from alumina, synthetic magnesite, silica, boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide, magnesium oxide, talc, mica, and hydrotalcite. is there. More preferably, the thermally conductive filler is at least one selected from alumina, silica, boron nitride and aluminum nitride. The use of these inorganic fillers enhances the thermal conductivity of the laminate.

It is further preferable that the thermally conductive filler is at least one selected from alumina and boron nitride, and it is even more preferable to use both of them. Since boron nitride is a material having a low relative dielectric constant, as will be described later, when boron nitride is contained in the first insulating layer 12A (region on the one surface 12X side), the ratio of the region on the one surface 12X side is increased. It is easy to lower the dielectric constant. On the other hand, by including alumina in the second insulating layer 12B (region on the side of the other surface 12Y), the relative dielectric constant of the one surface 12X side is made lower than that of the other surface 12Y side. It will be easier.
Further, when boron nitride is contained in a resin layer or the like, the resin layer generally becomes brittle, but in the present invention, the insulating resin layer 12 becomes brittle by setting the solvent content to a certain value or more as described above. It is difficult, and therefore the sheet properties of the laminated body 10 are improved.
Boron nitride may be contained in both the first insulating layer 12A (region on the one surface 12X side) and the second insulating layer 12B (region on the other surface 12Y side). In that case, as described in detail below, in order to reduce the relative dielectric constant of the region on the one surface 12X side, the content of boron nitride in the region on the one surface 12X side is set to the other surface 12Y side. It is preferable that the content of boron nitride in the region is higher.
The shapes of boron nitride and alumina are as described in more detail in the first filler and second filler described later.

The shape of the heat conductive filler is not particularly limited and may be any of plate shape, spherical shape, amorphous shape, crushed shape, polygonal shape and the like. Further, the heat conductive filler may be agglomerated particles obtained by aggregating primary particles such as a plate-like filler.

(First filler)
The heat conductive filler of the present invention preferably contains a plate-like filler (also referred to as “first filler”). By containing the plate-like filler, the thermal conductivity tends to be good. The material of the first filler may be appropriately selected from those described above, and is preferably boron nitride. By using boron nitride, it is easy to improve the thermal conductivity and insulating property, and it is easy to lower the relative dielectric constant. Further, the first filler preferably has a lower relative dielectric constant than the second filler described later. Further, the first filler preferably constitutes agglomerated particles.
If the insulating resin layer 12 contains a plate-like filler or agglomerated particles, the sheet property may be deteriorated. However, as described above, by setting the solvent content within a certain range, the deterioration of the sheet property is suppressed. It

Boron nitride used as the first filler is prepared from hexagonal boron nitride, cubic boron nitride, boron nitride produced by a reduction nitriding method of a boron compound and ammonia, and a boron compound and a nitrogen-containing compound such as melamine. Examples thereof include boron nitride prepared, and boron nitride prepared from sodium borohydride and ammonium chloride. From the viewpoint of further effectively increasing the thermal conductivity, the boron nitride is preferably hexagonal boron nitride.

The aspect ratio of the plate-like filler (first filler) is preferably larger than 2, more preferably 3 or more, and further preferably 4 or more. Further, it is preferably 25 or less, more preferably 22 or less, and further preferably 20 or less. When it is 4 or more, the major axis (maximum length) of the primary particles of the plate-like filler becomes long, and it becomes easy to increase the thermal conductivity of the laminate. Further, when the ratio is 16 or less, the sheet property is likely to be improved.
In the present invention, the aspect ratio means the maximum length/minimum length in each filler (primary particle). The minimum length is the thickness of the plate filler. In the present specification, the aspect ratio is an average aspect ratio, and specifically, 50 particles arbitrarily selected are observed with an electron microscope or an optical microscope, and an average value of the maximum length/minimum length of each particle. It is obtained by calculating.

Further, in the primary particles of the plate-like filler, the average major axis, which is the average of the major axis (maximum length in each particle), is preferably 1 μm or more, more preferably 2 μm or more, from the viewpoint of suitably increasing the thermal conductivity. , Preferably 40 μm or less, more preferably 38 μm or less. The average major axis refers to the average of 100 major axes obtained in the above-described measurement of the aspect ratio.

As described above, the first filler may be aggregated particles. The agglomerated particles are secondary particles obtained by aggregating the primary particles made of the plate-like filler described above. By using the first filler as agglomerated particles, the thermal conductivity can be more effectively enhanced while ensuring the insulating property. The plate-like filler is preferably boron nitride as described above, that is, the agglomerated particles are preferably boron nitride agglomerated particles.

The method for producing the aggregated particles is not particularly limited, and examples thereof include a spray drying method and a fluidized bed granulation method. The method for producing the aggregated particles is preferably a spray drying (also called spray drying) method. The spray drying method can be classified into a two-fluid nozzle method, a disk method (also called a rotary method), an ultrasonic nozzle method, and the like depending on the spray method, and any of these methods can be applied. The ultrasonic nozzle method is preferable from the viewpoint that the total pore volume can be controlled more easily.

The agglomerated particles are preferably boron nitride agglomerated particles as described above, but the boron nitride agglomerated particles are preferably produced by using boron nitride primary particles as a raw material. The boron nitride used as the raw material of the boron nitride agglomerated particles is not particularly limited, and includes hexagonal boron nitride, cubic boron nitride, boron nitride produced by a reduction nitriding method of a boron compound and ammonia, a boron compound and melamine, and the like. Examples thereof include boron nitride produced from a nitrogen compound, boron nitride produced from sodium borohydride and ammonium chloride, and the like. From the viewpoint of further effectively increasing the thermal conductivity of the boron nitride agglomerated particles, the boron nitride used as the material of the boron nitride agglomerated particles is preferably hexagonal boron nitride.

Further, the granulation step is not always necessary as a method for producing aggregated particles. For example, the boron nitride agglomerated particles may be boron nitride agglomerated particles formed by spontaneously concentrating the primary particles of boron nitride as the boron nitride crystal grows. The agglomerated particles may be crushed agglomerated particles in order to make the particle diameters of the agglomerated particles uniform.

From the viewpoint of effectively increasing the insulating property and the thermal conductivity, the average particle size of the aggregated particles is preferably 12 μm or more, preferably 15 μm or more, and preferably 200 μm or less, It is more preferably 150 μm or less.
The average particle size can be measured using a "laser diffraction type particle size distribution measuring device" manufactured by Horiba Ltd. Regarding the method of calculating the average particle diameter, the particle diameter (d50) of the heat conductive filler when the cumulative volume is 50% is adopted as the average particle diameter.

(Second filler)
The heat conductive filler of the present invention may contain a heat conductive filler other than the plate-like filler described above. Examples of such a filler include a thermally conductive filler having an aspect ratio of 2 or less (hereinafter, also referred to as “second filler”).
The aspect ratio of the second filler is preferably 1.8 or less, more preferably 1.5 or less. By using the heat conductive filler having a low aspect ratio as described above, it becomes possible to enhance the heat conductivity without deteriorating the sheet property, the insulating property and the like. The aspect ratio of the second filler may be 1 or more.
The shape of the second filler is not particularly limited, and examples thereof include a spherical shape and a crushed shape. The material of the second filler may be appropriately selected from those described above, but the second filler is preferably alumina.

The average particle diameter of the second filler is preferably 0.1 μm or more, more preferably 0.5 μm or more, and preferably 1 μm or more. Further, it is preferably 20 μm or less, more preferably 15 μm or less, and further preferably 10 μm or less. When the average particle diameter is not less than these lower limit values, the second filler can be contained in the insulating resin layer in a high filling amount. Further, if it is not more than the upper limit value, the insulating property is easily enhanced. Furthermore, when the second filler having an average particle diameter within these ranges is used together in the same region as the above-mentioned first filler (for example, the first insulating layer 12A), the second filler is mixed between the first fillers. It is possible to easily enter into the gap and effectively improve the thermal conductivity of the laminate.

In the present invention, the relative dielectric constant of the insulating resin layer 12 is adjusted by the thermally conductive filler contained in the insulating resin layer 12. Specifically, the relative permittivity may be adjusted depending on the type of thermally conductive filler used. For example, a filler having a low relative dielectric constant (also referred to as a “low dielectric constant filler”) is contained in a thermally conductive filler contained in a region on one surface 12X side (that is, the first insulating layer 12A), and the other A filler having a high relative dielectric constant (also referred to as a “high dielectric constant filler”) may be used as the thermally conductive filler contained in the region on the surface 12Y side (that is, the second insulating layer 12B).
Further, a low dielectric constant filler is contained in both the region on the one surface 12X side (that is, the first insulating layer 12A) and the region on the other surface 12Y side (that is, the second insulating layer 12B). The content of the low dielectric constant filler in the area on the one surface 12X side may be higher than the content of the low dielectric constant filler in the area on the other surface 12Y side. The content of the low dielectric constant filler here means the ratio of the content of the low dielectric constant filler to the mass of the region (for example, each insulating layer) in which each filler is contained.
The low dielectric constant filler is, for example, the above-mentioned first filler, and is, for example, boron nitride. The high-dielectric-constant filler is, for example, the above-mentioned second filler and may be a filler having a higher relative dielectric constant than the low-dielectric-constant filler, and examples thereof include alumina.

In the insulating resin layer 12, the content of the thermally conductive filler is preferably 40% by mass or more and 96% by mass or less, more preferably 55% by mass or more and 95% by mass or less, and 65% by mass or more 93 in terms of the total amount of the insulating resin layer. It is more preferably not more than mass %. By setting the content within these ranges, it becomes easy to improve the sheet property, the insulating property, and the thermal conductivity.

As described above, the insulating resin layer 12 preferably has the first and second insulating layers 12A and 12B. In this case, it is preferable that both the first and second insulating layers 12A and 12B contain a heat conductive filler. That is, the 1st and 2nd insulating layers 12A and 12B (namely, the area|region by the side of one surface 12X, the area|region by the side of the other surface 12Y) are respectively 1st and 1st which contain a heat conductive filler, as mentioned later. Preferably, the curable composition of No. 2 is used.
In the first insulating layer 12A (that is, the first curable composition), the content of the thermally conductive filler is preferably 40% by mass or more and 94% by mass or less, more preferably 55% by mass or more and 90% by mass or less. , More preferably 65% by mass and 87% by mass or less. Within the range, it becomes easy to improve the thermal conductivity of the first insulating layer 12A while ensuring the insulating property.

As the thermally conductive filler contained in the first insulating layer 12A, the first filler may be used alone, or the first filler and the second filler may be used in combination. Further, as the first filler, it is preferable to use boron nitride or the like having a low relative dielectric constant as described above. On the other hand, the second filler is a filler having a higher relative dielectric constant than the first filler, and is preferably alumina.
When the first filler is used alone in the first insulating layer 12A, the relative permittivity on the side of the one surface 12X is easily lowered, and the insulating property is easily improved. Further, when the first and second fillers are used in combination, it becomes easy to improve the insulating property, the thermal conductivity, and the adhesion to the thermal conductor 11 in a well-balanced manner.

The content of the first filler in the first insulating layer 12A (that is, the first curable composition) is preferably 20% by mass or more and 84% by mass or less, more preferably 30% by mass or more and 80% by mass or less, It is more preferably 45% by mass or more and 75% by mass or less. Within this range, it becomes easy to improve the thermal conductivity of the first insulating layer 12A while ensuring the adhesiveness with the thermal conductive body 11 and the insulating property. Further, by using a filler having a low relative permittivity as described above within the above range and as the first filler (for example, boron nitride), the relative permittivity of the region on the one surface 12X side of the insulating resin layer 12 is Can be lowered.

Further, the content of the second filler in the first insulating layer 12A (that is, the first curable composition) is, for example, 70% by mass or less. When the content is 70% by mass or less, the first insulating layer 12A can contain the first filler in a certain amount or more, and the relative dielectric constant of the region on the one surface 12X side of the insulating resin layer 12 is low. It becomes easier to improve the insulation. The first insulating layer 12A (that is, the region on the one surface 12X side) from the viewpoint of improving the insulating property, thermal conductivity, and adhesion to the thermal conductor 11 in a well-balanced manner while lowering the relative dielectric constant. In the case where the second filler is contained in, the content of the second filler is more preferably 10% by mass or more and 60% by mass or less, and further preferably 20% by mass or more and 45% by mass or less.

The mass ratio (A2/A1) of the content (A2) of the second filler to the content (A1) of the first filler in the first insulating layer 12A (that is, the first curable composition) is 2 or less is preferable, 1.5 or less is more preferable, and 1.2 or less is further preferable. When the mass ratio (A2/A1) is set to a certain value or less, the first insulating layer 12A can contain the first filler in a certain amount or more, and the area of the insulating resin layer 12 on the one surface 12X side is reduced. It becomes easier to improve the insulation by lowering the relative dielectric constant.
Further, from the viewpoint of improving the insulation property, heat dissipation property, and adhesion to the heat conductor 11 in a well-balanced manner while lowering the relative dielectric constant, the first insulating layer 12A (that is, the region on the one surface 12X side) When the second filler is contained in (), the mass ratio (A2/A1) is preferably 0.2 or more, more preferably 0.3 or more, and further preferably 0.5 or more.

In the second insulating layer 12B (that is, the second curable composition), the content of the thermally conductive filler is preferably 40% by mass or more and 96% by mass or less, more preferably 55% by mass or more and 95% by mass or less. More preferably 70% by mass or more and 94% by mass or less. Within the range, it becomes easy to improve the thermal conductivity of the first insulating layer 12A while ensuring the insulating property.

As the thermally conductive filler contained in the second insulating layer 12B (that is, the second curable composition), it is preferable to use the second filler. As described above, a filler having a higher relative dielectric constant than the first filler such as alumina may be used as the second filler, and thus the second filler may be contained in the second insulating layer 12B. Thus, the relative permittivity of the region on the other surface 12Y side of the insulating resin layer 12 can be easily made higher than the relative permittivity of the region on the one surface 12X side, and the insulating property is improved.
In the second insulating layer 12B, the second filler may be used alone, or the second filler and the first filler may be used in combination. As described above, boron nitride or the like having a low relative dielectric constant may be used as the first filler.

The content of the second filler in the second insulating layer 12B (that is, the second curable composition) is preferably 25% by mass or more and 96% by mass or less, more preferably 40% by mass or more and 95% by mass or less, More preferably 50% by mass and 94% by mass or less. Within the range, it becomes easy to improve the thermal conductivity of the laminated body 10 while ensuring the insulating property.

The content of the first filler in the second insulating layer 12B (that is, the second curable composition) is, for example, less than 50% by mass. By setting the amount to be less than 50% by mass, the relative dielectric constant of the second insulating layer 12B is likely to be higher than that of the first insulating layer 12B, and the deterioration of the sheet property is prevented.
From these viewpoints, when the first filler is contained in the second insulating layer 12B (that is, the second curable composition), the content of the first filler is 10% by mass or more and 45% by mass or less. It is more preferably 20% by mass and 40% by mass or less.

The mass ratio (A1/A2) of the content (A1) of the first filler to the content (A2) of the second filler in the second insulating layer 12B (that is, the second curable composition) is , Less than 1.5 is preferable, less than 1 is more preferable, and less than 0.8 is further preferable. When the mass ratio (A1/A2) is set to a certain value or less, the second insulating layer 12B does not contain the first filler more than necessary, and while improving the sheet property, the ratio of the area on the one surface 12X side It is easy to lower the dielectric constant. Also, the adhesiveness with the conductive layer is less likely to decrease.
In addition, when the first filler is contained in the second insulating layer 12B (that is, the second curable composition), the mass ratio (A1/A2) is: 0.1 or more is preferable, 0.3 or more is more preferable, and 0.4 or more is further preferable.

(Curable compound)
The insulating resin layer 12 is formed from a curable composition containing a curable compound and a heat conductive filler. The curable compound constitutes the matrix resin of the insulating resin layer 12 by being thermally cured. Further, the curable compound is preferably cured with a thermosetting agent. That is, the curable composition preferably contains a thermosetting agent in addition to the curable compound and the heat conductive filler.
As described above, the insulating resin layer 12 preferably has the first and second insulating layers 12A and 12B formed from the first and second curable compositions, respectively, but the first and second curing layers The composition comprises a curable compound and a thermally conductive filler, and preferably a thermosetting agent in addition to the curable compound and the thermally conductive filler.

In the present invention, the curable compound is preferably a curable compound having an epoxy group, and specifically, it is preferable to use an epoxy resin, a phenoxy resin, or both of them. By using the epoxy resin, the phenoxy resin, or both of them, the heat resistance, the sheet property, the adhesion to the heat conductor 11, the adhesion to the conductive layer, and the like are improved.

<Epoxy resin>
Examples of the epoxy resin include compounds containing two or more epoxy groups in the molecule. The epoxy resin has a weight average molecular weight of less than 5,000.
Specific examples of the epoxy resin include styrene skeleton-containing epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, biphenol type epoxy resin, naphthalene type epoxy resin, Fluorene type epoxy resin, phenol aralkyl type epoxy resin, naphthol aralkyl type epoxy resin, dicyclopentadiene type epoxy resin, anthracene type epoxy resin, epoxy resin having adamantane skeleton, epoxy resin having tricyclodecane skeleton, and skeleton of triazine nucleus Examples of the epoxy resin include Among these, bisphenol A type epoxy resin is preferable.

The epoxy equivalent of the epoxy resin is not particularly limited, but is, for example, 100 g/eq or more and 500 g/eq or less, preferably 120 g/eq or more and 400 g/eq or less, and more preferably 150 g/eq or more and 350 g/eq or less.
The epoxy equivalent can be measured, for example, according to the method specified in JIS K7236.

<Phenoxy resin>
The phenoxy resin is, for example, a resin obtained by reacting epihalohydrin with a divalent phenol compound, or a resin obtained by reacting a divalent epoxy compound with a divalent phenol compound. The phenoxy resin has a bisphenol A type skeleton, a bisphenol F type skeleton, a bisphenol A/F mixed type skeleton, a naphthalene skeleton, a fluorene skeleton, a biphenyl skeleton, an anthracene skeleton, a pyrene skeleton, a xanthene skeleton, an adamantane skeleton, or a dicyclopentadiene skeleton. It is preferable. The phenoxy resin preferably has a bisphenol A type skeleton, a bisphenol F type skeleton, a bisphenol A/F mixed type skeleton, a naphthalene skeleton, a fluorene skeleton or a biphenyl skeleton, and more preferably has a bisphenol A type skeleton.

The weight average molecular weight of the phenoxy resin is 10,000 or more, preferably 20,000 or more, more preferably 30,000 or more, preferably 1,000,000 or less, more preferably 250,000 or less. Even if a resin having such a high molecular weight is used as the resin, in the present invention, since the insulating resin layer is formed by applying a diluting solution obtained by diluting the curable composition as described below, the laminate can be easily formed. Can be formed. The weight average molecular weight is a polystyrene equivalent weight average molecular weight measured by gel permeation chromatography (GPC). In gel permeation chromatography (GPC) measurement, tetrahydrofuran may be used as an eluent.
The epoxy equivalent of the phenoxy resin is not particularly limited, but is, for example, 2500 g/eq or more and 25000 g/eq or less, preferably 4000 g/eq or more and 18000 g/eq or less, and more preferably 5000 g/eq or more and 13000 g/eq or less.

In the present invention, as described above, the insulating resin layer 12 preferably has the first and second insulating layers 12A and 12B formed of the first and second curable compositions. In the first curable composition, the content of the curable compound is preferably 5% by mass or more and 55% by mass or less, more preferably 8% by mass or more and 40% by mass or less, and further 9% by mass or more and 30% by mass or less. preferable. Within these ranges, it becomes easy to secure various performances such as sheet property.
In the second curable composition, the content of the curable compound is preferably 3% by mass or more and 55% by mass or less, more preferably 4% by mass or more and 35% by mass or less, and 5% by mass or more and 25% by mass or less. Is more preferable. Within these ranges, it becomes easy to secure various performances such as sheet property.

When each of the first and second curable compositions contains both an epoxy resin and a phenoxy resin, the content of the epoxy resin is 40% by mass or more and 90% by mass or less based on the total amount of these, and the phenoxy The content of the resin is preferably 10% by mass or more and 60% by mass or less. Further, it is more preferable that the content of the epoxy resin is 50% by mass or more and 80% by mass or less, the content of the phenoxy resin is 20% by mass or more and 50% by mass or less, and the content of the epoxy resin is 55% by mass or more. It is more preferably 75% by mass or less and the content of the phenoxy resin is 25% by mass or more and 45% by mass or less.
<Thermosetting agent>
When the above epoxy resin or phenoxy resin is used as the thermosetting agent, a phenol compound (phenol thermosetting agent), an amine compound (amine thermosetting agent), an imidazole compound, an acid anhydride, etc. may be mentioned. Among these, imidazole compounds are preferable.

Examples of the phenol compound include novolac type phenol, biphenol type phenol, naphthalene type phenol, dicyclopentadiene type phenol, aralkyl type phenol and dicyclopentadiene type phenol.
Examples of the amine compound include dicyandiamide, diaminodiphenylmethane and diaminodiphenylsulfone.

Examples of the imidazole compound include 2-undecylimidazole, 2-heptadecylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2. -Methylimidazole, 1-benzyl-2-phenylimidazole, 1,2-dimethylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecyl Imidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'- Methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6 -[2'-Ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s- Triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-dihydroxymethylimidazole, etc. Are listed.

Examples of the acid anhydride include styrene/maleic anhydride copolymer, benzophenone tetracarboxylic acid anhydride, pyromellitic acid anhydride, trimellitic acid anhydride, 4,4′-oxydiphthalic acid anhydride, phenylethynylphthalic acid anhydride, and glycerol. Examples thereof include bis(anhydrotrimellitate) monoacetate, ethylene glycol bis(anhydrotrimellitate), methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and trialkyltetrahydrophthalic anhydride.

In each of the first and second curable compositions for forming the first and second insulating layers 12A and 12B (that is, the area on the one surface 12X side, the area on the other surface 12Y side), heat is applied. The content of the curing agent is, for example, 1 part by mass or more and 100 parts by mass or less, preferably 10 parts by mass or more and 90 parts by mass or less, and more preferably 20 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the curable compound. Is. However, the first insulating layer 12A is more preferably 40 parts by mass or more and 70 parts by mass or less among the above in order to increase the curing rate and the adhesion with the heat conductor 11.
Further, the content (that is, the content ratio) of the thermosetting agent with respect to 100 parts by mass of the curable compound is preferably higher in the first insulating layer than in the second insulating layer. By increasing the content of the first insulating layer, it becomes easy to increase the curing rate of the first insulating layer 12A (that is, the region on the one surface 12X side).

In the above, the curable compound has been described as being a curable compound having an epoxy group, but the curable compound is not limited to a curable compound having an epoxy group, and may be a melamine compound, an oxetanyl compound, an isocyanate compound, or the like. The heat curing agent may also be appropriately selected according to the curable compound.

(Dispersant)
The curable composition (ie, each of the first and second curable compositions) may contain a dispersant. The dispersant makes it easier to disperse the thermally conductive filler in the resin component, and improves the insulating property and thermal conductivity of the laminate.
As the dispersant, for example, alkoxysilanes are used. Examples of alkoxysilanes include alkoxysilanes having a reactive group and alkoxysilanes having no reactive group. The reactive group in the alkoxysilane having a reactive group is selected from, for example, an epoxy group, a (meth)acryloyl group, an amino group, a vinyl group, a ureido group, a mercapto group, and an isocyanate group. The alkoxysilanes are preferably those having a reactive group, more preferably those having an epoxy group.
Examples of the alkoxysilane having an epoxy group include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxy. Examples include propyltriethoxysilane.
In each of the first and second curable compositions, the content of the dispersant is preferably 0.01% by mass or more and 2% by mass or less, more preferably 0.02% by mass or more and 1.5% by mass or less, and 0.05 More preferably, the content is 1% by mass or more and 1% by mass or less. By setting the lower limit value or more, it becomes easy to disperse the thermally conductive filler in each insulating layer. Further, by setting the content to the upper limit or less, it becomes easy to obtain the effect corresponding to the blending amount.

The resin composition of the present invention contains, in addition to the above components, a flame retardant, an antioxidant, an ion scavenger, a tackifier, a plasticizer, a thixotropic agent, a photosensitizer and a colorant. Good.

The insulating resin layer 12 has a thickness of, for example, 0.04 mm or more and 0.30 m or less, preferably 0.06 mm or more and 0.25 mm or less. By setting the lower limit value or more, it becomes easy to secure the insulation property. Further, by setting the upper limit value or less, it becomes easy to reduce the thickness of the electronic component.
The ratio (T2/T1) of the thickness (T2) of the second resin layer to the thickness (T1) of the first insulating layer 12A is, for example, 1/9 or more and 9 or less, and preferably 2/ It is 8 or more and 8/2 or less.

[Thermal conductor]
The heat conductor 11 is not particularly limited as long as it has a heat conductivity of 10 W/m·K or more. Examples thereof include aluminum, copper, alumina, beryllia, silicon carbide, silicon nitride, aluminum nitride, and graphite sheet. Above all, the heat conductor 11 is preferably copper or aluminum. Copper or aluminum has high thermal conductivity and excellent heat dissipation. The thermal conductivity of the thermal conductor 11 can be measured by the laser flash method.
The thickness of the heat conductor 11 is, for example, 0.03 mm or more and 3 mm or less, preferably 0.1 mm or more and 2.5 mm or less.

In the above description, the insulating resin layer 12 is mainly composed of two layers, that is, the first and second insulating layers 12A and 12B, as shown in FIG. The structure is not limited to the two-layer structure. For example, a third insulating layer may be provided between the first and second insulating layers. The third insulating layer typically contains a heat conductive filler as described above, and the heat conductive filler may be appropriately selected from the above heat conductive fillers. In this case, the relative dielectric constant of the third insulating layer is preferably larger than that of the first insulating layer and smaller than that of the second insulating layer.
Further, the relative dielectric constant may be gradually increased from one surface 12X of the insulating resin layer 12 toward the other surface 12Y. In this case, the insulating resin layer 12 may be formed by laminating four or more thin film insulating layers that are sufficiently thinner than the entire thickness of the insulating resin layer 12, for example. In this case, the relative permittivity of each thin-film insulating layer may be adjusted by adjusting, for example, the type and content of the filler.

(Method for manufacturing laminated body)
In the present invention, a diluting liquid of the curable composition for forming the insulating resin layer may be prepared, and the diluting liquid of the curable composition may form the insulating resin layer. Hereinafter, the method for producing a laminate of the present invention will be described in detail when the insulating resin layer is composed of the first and second insulating layers.

First, a diluting solution of the first and second curable compositions for forming the first and second insulating layers is prepared. Specifically, a curable compound, a heat conductive filler, and a heat curing agent and other additives to be blended as necessary are mixed with an organic solvent to obtain the first and second curability. A diluted solution of the composition may be prepared.

Here, the solvent for diluting the resin composition liquid is not particularly limited, but is an aliphatic hydrocarbon solvent such as n-pentane, n-hexane, n-heptane or cyclohexane, or an aromatic hydrocarbon such as toluene. Examples thereof include system solvents, ester solvents such as ethyl acetate and n-butyl acetate, ketone solvents such as acetone, methyl ethyl ketone (MEK) and cyclohexanone. These organic solvents may be used alone or in combination of two or more. Of these, methyl ethyl ketone and cyclohexanone are preferable, and a mixed solvent thereof may be used.
The solid content concentration in each of the diluting liquids of the first and second curable compositions is, for example, 60 to 96% by mass, preferably 65 to 95% by mass, and more preferably 70 to 94% by mass. When the solid content concentration is at least the lower limit value, the insulating layer can be efficiently formed. Further, by setting the solid content concentration to be not more than the upper limit value, it becomes easy to adjust the viscosity of the diluting liquid of the curable composition to an appropriate value, and it is difficult for process defects to occur.

Next, the diluting liquid of the first curable composition may be applied to a release sheet or the like and dried to form the first insulating layer on the release sheet. Similarly, the diluting liquid of the second curable composition may be applied to a release sheet or the like and dried to form the second insulating layer on the release sheet.

As described above, the insulating resin layer 12 has a solvent content within a predetermined range (50 to 2000 ppm). In this manufacturing method, the organic solvent used for diluting the first and second curable compositions is allowed to remain in the insulating layers 12A and 12B in a minute amount so that the solvent content of the insulating resin layer 12 falls within a certain range. do it.
In the present manufacturing method, in order to keep the solvent content in the insulating resin layer 12 within a certain range, the drying time and the drying temperature in drying the diluted liquid of the first and second curable compositions are relatively moderate. It must be done under certain conditions.
Specifically, the drying temperature may be appropriately set depending on the type of solvent and the like, but may be set, for example, in the range of 60° C. or higher and 120° C. or lower, preferably 75° C. or higher and 100° C. or lower. The drying time is, for example, 5 minutes or more and 60 minutes or less, preferably 10 minutes or more and 40 minutes or less. Drying may be performed with hot air, or a release sheet coated with the diluting liquid of the curable composition may be placed in a drying oven or oven to be dried.

The solvent content in each of the first and second insulating layers after drying is, for example, 100 ppm or more and 2500 ppm or less. By setting it to 100 ppm or more and 2500 ppm or less, it becomes easy to adjust the solvent content in the insulating resin layer 12 of the laminated body 10 within the above-mentioned predetermined range.
The solvent content (content ratio) in the first and second insulating layers after drying may be different from each other. For example, the solvent content in the first insulating layer after drying is It suffices if it is higher than the solvent content in the second insulating layer. As described above, the first insulating layer contains a first filler such as boron nitride and tends to be brittle, but when the solvent content is relatively increased, the first insulating layer is less likely to be brittle and has good sheet properties. Become.
From such a viewpoint, the solvent content in the first insulating layer is more preferably 200 ppm or more and 1500 ppm or less, and further preferably 500 ppm or more and 1200 ppm or less.
Further, the solvent content in the second insulating layer is more preferably 100 ppm or more and 1000 ppm or less, still more preferably 150 ppm or more and 800 ppm or less.

The first and second insulating layers produced as described above are sequentially laminated on a heat conductor and, if necessary, cured to obtain a laminate. Specifically, first, the first insulating layer peeled off from the release sheet may be laminated on the heat conductor, and then the first insulating layer may be cured if necessary (first curing step). .. Next, the second insulating layer peeled off from the release sheet is laminated on the first insulating layer, and then the first and second insulating layers or the second insulating layer is cured, if necessary. Good (second curing step). The curing in the first and second curing steps is performed by heating. In the present manufacturing method, by performing the curing twice, it becomes easy to adjust the curing rates of the first insulating layer and the second insulating layer to different values.

Here, in the first and second curing steps, the heating temperature and the heating time may be adjusted so that the first and second insulating layers have desired curing characteristics.
Specifically, the heating temperature in the first curing step is, for example, 100°C or higher and 230°C or lower, preferably 120°C or higher and 210°C or lower. The heating time within these temperature ranges is, for example, 30 minutes or more and 5 hours or less, preferably 1 hour or more and 3 hours or less.

The heating temperature in the second curing step is usually lower than the heating temperature in the first curing step. When the heating temperature in the second curing step is lowered, the curing rate of the second insulating layer tends to be lower than that of the first insulating layer.
Specifically, the heating temperature in the second curing step is, for example, 80°C or higher and 150°C or lower, preferably 90°C or higher and 130°C or lower. The heating time within these temperature ranges is, for example, 1 minute or more and 10 minutes or less, preferably 1 minute or more and 5 minutes or less. By setting the heating temperature in the second curing step and the heating temperature within the above range, it becomes easy to adjust the curing rate of the second insulating layer to a desired range.
However, when the second insulating layer is uncured, the second curing step may be omitted.

Further, in the above, the curing step is performed by being divided into a first step of curing the first insulating layer and a second curing step of mainly curing the second insulating layer. The two insulating layers may be collectively performed in the same curing process. Specifically, for example, the first insulating layer and the second insulating layer may be sequentially laminated on the heat conductor and then heated to cure the first and second insulating layers.
In this case, the curing rates of the first insulating layer and the second insulating layer can be appropriately adjusted by, for example, the content of the thermosetting agent contained in each layer.

In the manufacturing method described above, the first insulating layer and the second insulating layer formed on the release sheet are sequentially transferred to the heat conductor, but the release sheet may not be used. In such a case, the first insulating layer may be formed by directly applying it to the heat conductor and drying it. In addition, the second insulating layer may be formed by directly coating on the first insulating layer formed on the heat conductor and drying.

In addition, in the above-described manufacturing method, when the first insulating layer and the second insulating layer are laminated or cured, the first insulating layer and the laminated body of the first and second insulating layers are formed. Etc. may be pressurized if necessary. For example, when the first insulating layer is pressed when the first insulating layer is heated and cured, the adhesion between the first insulating layer and the heat conductor is improved.

In addition, although the manufacturing method of the laminated body in which the insulating resin layer is composed of the first and second insulating layers has been described above, the same method can be used even when the insulating resin layer has another configuration. For example, when the insulating resin layer is composed of three or more insulating layers, a plurality of insulating layers may be sequentially laminated on the heat conductor. Further, the curing of each insulating layer may be performed by heating each time one layer is laminated on the heat conductor, but may be performed by heating each time a plurality of layers are laminated, for example.

(Uses of laminate)
The laminated body 10 is used, for example, as a component of an electronic component, and is specifically used as a substrate on which a circuit or the like is attached, and preferably used as a substrate in a power semiconductor module. That is, the present invention also provides an electronic component including the above-described laminated body and a power semiconductor module including the electronic component.
The power semiconductor module is used in industrial equipment such as an inverter, an elevator, and an uninterruptible power supply (UPS), and is preferably an inverter.

In the laminated body 10, a conductive layer such as a lead frame is attached to the surface of the other surface 12Y. More specifically, in the laminated body 10, a conductive layer (not shown) is arranged on the other surface 12Y of the insulating resin layer 12, and then the insulating resin layer 12 is heated and cured, A conductive layer may be attached to the laminate 10. In the present invention, the region on the other surface 12Y side of the insulating resin layer 12 (for example, the second insulating layer 12B) is semi-cured or uncured as described above, so that the insulating resin layer 12 is cured. The conductive layer and the insulating resin layer 12 are firmly bonded together.
In addition, in the laminated body 10, after the conductive layer is arranged on the other surface 12Y, the laminated body 10 in which the conductive layers are laminated may be embedded in a mold resin or the like. In this case, the embedding of the mold resin may be performed after the insulating resin layer 12 is hardened or before it is hardened.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

In addition, the measuring method of each physical property is as follows.
[Amount of solvent in each insulating layer after drying]
The amount of solvent in each insulating layer is determined by using a gas chromatography mass spectrometer (GC-MS) (“JMS Q-1500” manufactured by JEOL Ltd.). 1 to 2 g of each insulating layer is sampled, placed in a GC-MS-dedicated container, sealed, and heated at 35° C. for 15 minutes, and the detected solvent amount is used as the solvent amount of each insulating layer.
[Relative permittivity]
The first and second insulating layers produced in each example and comparative example were peeled off from the release PET sheet, and both surfaces thereof were sandwiched between a copper foil (thickness 40 μm) and an aluminum plate (thickness 1.0 mm), respectively. Curing was carried out under the same conditions as in Examples and Comparative Examples to obtain sample sheets. The obtained sample sheet was cut into 40 mm×40 mm, and a φ20 mm pattern was processed by etching. After that, the relative permittivity was measured at 33 points for 1 cycle by dividing the frequency range from 100 mHz to 10 MHz on a log scale with an LCR (impedance) analyzer “PSM3750” manufactured by Iwasaki Communication Co., Ltd. at a room temperature, and the obtained waveform was obtained. By reading, the relative permittivity at a frequency of 1 MHz was obtained.

[Curing rate]
The curing rate is obtained by measuring the heat of curing when heating the corresponding region of the insulating resin layer. When measuring the curing rate, a differential scanning calorimeter (DSC) device (“DSC7020” manufactured by SII Nano Technology Co., Ltd.) is used. The curing rate is specifically measured as follows.
At a measurement start temperature of 30° C. and a heating rate of 8° C./min, the components in the corresponding region of the insulating resin layer are sampled (sample weight: 20 to 30 mg), heated to 180° C. and held for 1 hour. The amount of heat generated when the sample is cured at this temperature rise (hereinafter referred to as "heat amount A") is measured. Also, a release PET (polyethylene terephthalate) sheet having a thickness of 50 μm was coated with a curable composition for forming each region so as to have a thickness of 80 μm, and it was subjected to room temperature vacuum at 23° C. and 0.01 atm. An uncured insulating resin layer that has been dried without heating is prepared in the same manner as the insulating resin layer in the corresponding region except that it is dried for a time. Using this insulating resin layer, in the same manner as the above-mentioned measurement of the heat quantity A, the heat quantity (hereinafter, referred to as “heat quantity B”) generated when the temperature is increased and cured is measured. From the obtained heat amount A and heat amount B, the curing rate is calculated by the following formula.
Curing rate (%)=[1-(heat amount A/heat amount B)]×100

[Solvent Content in Insulating Resin Layer of Laminate]
The amount of solvent in the insulating resin layer of the laminate is determined by using a gas chromatography mass spectrometer (GC-MS) (“JMS Q-1500” manufactured by JEOL Ltd.). The insulating resin layer portion of the laminate is evenly sampled in the thickness direction in an amount of 1 to 2 g, placed in a GC-MS dedicated container, hermetically sealed, heated at 35° C. for 15 minutes, and the detected solvent amount is adjusted to the insulating layer. Of solvent.

The laminates obtained in Examples and Comparative Examples were evaluated by the following methods.
[Insulation evaluation]
A circular copper foil having a diameter of 2 cm was patterned on the other surface of the obtained laminated body where the heat conductor was not provided, to obtain a test sample. An AC voltage was applied at 25° C. by using a withstand voltage tester (“MODEL7473” manufactured by ETECH Electronics) so that the voltage increased at a rate of 0.33 kV/sec between the test samples. The voltage at which a current of 10 mA passed through the test sample was defined as the dielectric breakdown voltage. The breakdown voltage was normalized by dividing the breakdown voltage by the sample thickness, and the breakdown strength was calculated. The dielectric breakdown strength was judged according to the following criteria.
A: 60 kV/mm or more B: 50 kV/mm or more and less than 60 kV/mm C: less than 50 kV/mm

[Sheet property evaluation]
In each of the examples and comparative examples, a PET sheet is used instead of the copper plate, and the first and second insulating layers are laminated on the PET sheet in the same manner as in each of the examples and comparative examples to obtain a laminate sheet. Got The laminate sheet was cut into a size of 20 cm×10 cm, had both ends of 20 cm, and was bent at 90°, and the state of the sheet was evaluated according to the following evaluation criteria.
A: No crack B: Crack

[Heat dissipation evaluation]
After cutting the laminates obtained in Examples and Comparative Examples into 1 cm squares, a measuring device "Nanoflash" (NETZSCH, model number: LFA447) was used for a measurement sample in which carbon black was sprayed on both sides. The thermal conductivity was measured by the laser flash method. From the thermal conductivity, the heat dissipation was evaluated according to the following criteria.
A: 7 W/(m·K) or more B: 7 W/(m·K) or less

[Adhesion evaluation]
The obtained laminate was cut into a size of 50 mm×120 mm to obtain a test sample. The copper foil was peeled off so that the copper foil having a center width of 10 mm of the obtained test sample remained, and the adhesion with the copper foil having a center width of 10 mm was measured according to JIS C6481. As the measuring device, "Tensilon universal tester" manufactured by Orientec was used. The adhesion with the copper foil was measured for the five test samples. The average value of the measured adhesion values with the copper foil in the five test samples was taken as the adhesion value with the copper foil. The adhesion was evaluated according to the following criteria.
A: 6 N/cm or more B: less than 6 N/cm

The components used in Examples and Comparative Examples are as follows.
Epoxy resin: Bisphenol A type epoxy resin, Nippon Steel & Sumikin Chemical Co., Ltd., trade name "YD-127", epoxy equivalent: 180-190 eq/g
Phenoxy resin: Mitsubishi Chemical Co., Ltd., trade name "jER1256", epoxy equivalent: 7,500 to 8,500 eq/g, weight average molecular weight: about 50,000 Thermosetting agent: imidazole compound, Shikoku Chemicals Co., Ltd., Product name "2P4MZ"
First filler: boron nitride, plate-like filler, agglomerated particles, “HP-40” manufactured by Mizushima Gokin Co., Ltd., aspect ratio 6, average major axis of primary particles 7 μm, average particle size of agglomerated particles 40 μm
Second filler: alumina, aspect ratio 1, made by Micron, trade name "AZ-4", average particle size 5 μm
Dispersant: 3-glycidoxypropyltriethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM403"

[Example 1]
According to the formulation of Table 1, first and second curable compositions for forming the first and second insulating layers were prepared. The first and second curable compositions were prepared as a diluting solution of each composition diluted with an organic solvent (MEK) so that the solid content concentrations were 75% by mass and 90% by mass, respectively.
The diluted solution of the first curable composition was applied onto a release PET sheet (thickness 40 μm) so that the thickness after drying would be 200 μm. Further, the diluting liquid of the second curable composition was applied onto another release PET sheet (thickness 40 μm) so that the thickness after drying would be 80 μm, and these were dried according to the drying conditions shown in Table 1 in an oven. It was dried inside, and each of the first and second insulating layers was formed on each release PET sheet.

Next, the first insulating layer formed on the release PET sheet was laminated on a copper plate (thickness 0.4 mm) while peeling off the release PET sheet. After that, the first insulating layer was heated at 170° C. for 2 hours to cure the first insulating layer.
Next, the second insulating layer formed on the release PET sheet was laminated on the first insulating layer while peeling off the release PET sheet. Then, the 2nd insulating layer was heated at 110 degreeC over 3 minutes, the 2nd insulating layer was semi-hardened, and the laminated body was obtained. In the laminate, the thickness of the first insulating layer was 0.1 mm and the thickness of the second insulating layer was 0.08 mm.

[Example 2]
Example 1 was carried out in the same manner as in Example 1 except that the compositions of the first and second curable compositions were changed to those shown in Table 1 and the thicknesses of the insulating layer and the copper plate were changed to those shown in the table.

[Example 3]
The composition of the first and second curable compositions was changed to the composition shown in Table 1, the drying conditions were changed as shown in Table 1, and the thicknesses of the insulating layer and the copper plate were changed to the thicknesses shown in the table. Example 1 was repeated except that

[Example 4]
The composition of the first and second curable compositions was changed to the composition shown in Table 1, the drying conditions were changed as shown in Table 1, and the thicknesses of the insulating layer and the copper plate were changed to the thicknesses shown in the table. Example 1 was repeated except that

[Comparative Example 1]
The composition of the first and second curable compositions was changed to the composition shown in Table 1, the drying conditions were changed as shown in Table 1, and the thicknesses of the insulating layer and the copper plate were changed to the thicknesses shown in the table. Example 1 was repeated except that

[Comparative example 2]
Example 1 was repeated except that the drying conditions were changed as shown in Table 1.

[Comparative Example 3]
Example 1 was repeated except that the drying conditions were changed as shown in Table 1.

As is clear from the results of Table 1, in each example, the relative dielectric constant of the first insulating layer 12A (the region on the one surface 12X side) is lowered, and the second resin layer 12B (the other surface 12Y side). Area) and the amount of solvent contained in the insulating resin layer is kept within a certain range, it is possible to improve heat dissipation and insulation, and also improve sheet properties. did it.

10 Laminated body 11 Thermal conductor 12 Insulating resin layer 12A First insulating layer 12B Second insulating layer 12X One surface 12Y The other surface

Claims (12)

A laminate comprising a heat conductor having a heat conductivity of 10 W/m·K or more and an insulating resin layer provided on the surface of the heat conductor and containing a heat conductive filler,
The relative dielectric constant of the surface of the insulating resin layer on which the heat conductor is provided is lower than the relative dielectric constant of the surface of the insulating resin layer opposite to the surface on which the heat conductor is provided,
A laminate, in which the solvent content of the insulating resin layer is 50 ppm or more and 2000 ppm or less. The laminate according to claim 1, wherein the insulating resin layer has at least an uncured product or a semi-cured product in a region on a surface side opposite to a surface on which the heat conductor is provided. The laminated body according to claim 2, wherein the insulating resin layer has at least a semi-cured product or a cured product in a region on a surface side on which the heat conductor is provided. The curing rate of the region on the side where the heat conductor is provided is 50% or more,
The curing rate of the region on the side opposite to the side on which the heat conductor is provided is less than 80%,
The hardening rate of the area|region of the surface side in which the said heat conductor is provided is larger than the hardening rate of the area|region of the surface side opposite to the surface in which the said heat conductor is provided. Stack of. The thermally conductive filler comprises boron nitride,
The said boron nitride is a laminated body as described in any one of Claims 1-4 contained in the area|region by the side of the surface where the heat conductor of the said insulating resin layer is provided. The heat conductive filler includes alumina,
The said alumina is contained in the area|region of the surface side opposite to the surface in which the thermal conductor of the said insulating resin layer is provided, The laminated body of any one of Claims 1-5. The laminate according to claim 6, wherein the aspect ratio of the alumina is 2 or less. The thermally conductive filler comprises boron nitride,
The laminated body according to claim 6 or 7, wherein boron nitride is further contained in a region of a surface of the insulating resin layer opposite to a surface on which the heat conductor is provided. The thermally conductive filler comprises boron nitride,
The area on the surface side on which the heat conductor is provided, and the area on the surface side opposite to the surface on which the heat conductor is provided both contain boron nitride,
In the insulating resin layer, the content rate of boron nitride in a surface side area on which the heat conductor is provided is higher than the content rate of boron nitride in a surface side area opposite to the surface on which the heat conductor is provided. Item 9. The laminate according to any one of items 1 to 8. The thickness of the said thermal conductor is 0.03 mm or more and 3 mm or less, The laminated body of any one of Claims 1-9. An electronic component comprising the laminate according to claim 1. An inverter comprising the electronic component according to claim 11.