JP2019150997A - Laminate - Google Patents

Abstract

To provide a laminate having high insulation property while having good thermal conductivity.SOLUTION: A laminate 10 has a metal base plate 16, a resin composition layer 14 containing an epoxy resin and an inorganic filler and a metal plate 12 in this order, in which porosity in a cross section of the resin composition layer 14 determined from image analysis is 0.09% or less in an area ratio. The inorganic filler contains plate-like inorganic particles having thermal conductivity of 10 W/(m K) or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laminate.

  In recent years, downsizing and higher performance of electronic and electrical devices have progressed, and the mounting density of electronic components has increased. For this reason, it is a problem how to dissipate the heat generated from the electronic components in a narrow space. Since heat generated from electronic components is directly linked to the reliability of electronic and electrical equipment, efficient dissipation of the generated heat is an urgent issue.

  As one means for solving the above-mentioned problem, there is a means that uses a ceramic substrate having high thermal conductivity as a heat dissipation substrate for mounting a power semiconductor device or the like. Examples of such a ceramic substrate include an alumina substrate and an aluminum nitride substrate.

  However, the means using the ceramic substrate has a problem that it is difficult to make a multilayer, workability is poor, and cost is very high. Furthermore, since the difference in coefficient of linear expansion between the ceramic substrate and the copper circuit is large, there is also a problem that the copper circuit is easily peeled off during the cooling and heating cycle.

  Therefore, a resin composition using boron nitride having a low linear expansion coefficient, particularly hexagonal boron nitride, has attracted attention as a heat dissipation material. The crystal structure of hexagonal boron nitride is a layered structure of hexagonal network similar to graphite, and the particle shape of hexagonal boron nitride is scaly. For this reason, hexagonal boron nitride is known to have higher thermal conductivity in the plane direction than thermal conductivity in the thickness direction and anisotropy in thermal conductivity.

  Secondary agglomerated particles (boron nitride agglomerated particles) in which the primary particles of hexagonal boron nitride are agglomerated as a method of reducing the thermal conductivity anisotropy of hexagonal boron nitride and improving the thermal conductivity in the thickness direction. It has been proposed to use For example, Patent Documents 1 to 3 disclose resin compositions using boron nitride aggregated particles.

  Patent Document 1 discloses a thermosetting resin composition containing an inorganic filler in a thermosetting resin. The inorganic filler includes a secondary aggregate (A) composed of primary particles of boron nitride having an average major axis of 8 μm or less, and a secondary aggregate composed of primary particles of boron nitride having an average major axis of more than 8 μm and 20 μm or less. The next aggregate (B) is contained in a volume ratio of 40:60 to 98: 2. Content of the said inorganic filler is 40 volume% or more and 80 volume% or less.

  Patent Document 2 discloses a curable heat-dissipating composition containing two kinds of fillers having different compressive fracture strengths (except when the two kinds of fillers are the same substance) and a curable resin (C). Has been. The compression fracture strength ratio (compression fracture strength of filler (A) having a high compression fracture strength / compression fracture strength of filler (B) having a small compression fracture strength) of the two kinds of fillers is 5 or more and 1500 or less. The filler (B) is hexagonal boron nitride aggregated particles.

  Patent Document 3 discloses a thermosetting resin composition containing a thermosetting resin and an inorganic filler. The inorganic filler is formed of secondary particles (A) formed from primary particles of boron nitride having an aspect ratio of 10 or more and 20 or less, and primary particles of boron nitride having an aspect ratio of 2 or more and 9 or less. Secondary particles (B).

JP2011-6586A WO2013 / 1455961A1 WO2014 / 199650A1

  In the curable composition using the conventional boron nitride aggregated particles as described in Patent Documents 1 to 3, in order to maintain the isotropic thermal conductivity of the boron nitride aggregated particles, during pressing such as sheet molding, It is necessary not to collapse the boron nitride aggregated particles by pressing. For this reason, voids may remain between boron nitride aggregated particles. As a result, although the thermal conductivity in the thickness direction can be improved, the insulating property may be lowered.

  In view of the above, an object of the present invention is to provide a laminate having high thermal conductivity while having good thermal conductivity.

  As a result of intensive studies to solve the above problems, the present inventors have conceived the following present invention and found that the problems can be solved. That is, the present invention is as follows.

[1] A laminate having a metal base plate, a resin composition layer containing an epoxy resin and an inorganic filler, and a metal plate in this order, and a void in a cross section of the resin composition layer obtained from image analysis The laminated body whose rate is 0.09% or less in area ratio.
[2] The laminate according to [1], wherein the inorganic filler includes plate-like inorganic particles having a thermal conductivity of 10 W / (m · K) or more.
[3] The inorganic filler includes plate-like inorganic particles, inorganic particles A, and inorganic particles B, and any one or more of the plate-like inorganic particles, the inorganic particles A, and the inorganic particles B is 10 W / The laminate according to [1], which has a thermal conductivity of (m · K) or more.
[4] The laminate according to [3], wherein the inorganic particles A have an aspect ratio of 2 or less.
[5] The laminate according to any one of [2] to [4], wherein the content of the plate-like inorganic particles in the inorganic filler is 30 to 100% by volume.
[6] The laminate according to any one of [2] to [5], wherein the plate-like inorganic particles are boron nitride.
[7] The laminate according to any one of [2] to [6], wherein the plate-like inorganic particles are aggregated particles.
[8] The laminate according to any one of [3] to [7], wherein the inorganic particles B have a compressive strength at 20% compression that is greater than that of the plate-like inorganic particles.
[9] The laminate according to any one of [3] to [8], wherein the inorganic particles B are boron nitride.
[10] The resin composition layer includes at least two layers, and has a first resin composition layer and a second resin composition layer in this order from the metal base plate side, and the first resin composition layer. The laminate according to any one of [3] to [9], in which includes the plate-like inorganic particles, and the second resin composition layer includes the inorganic particles A and the inorganic particles B.
[11] The laminate according to [10], wherein the first resin composition layer further includes the inorganic particles A.

  ADVANTAGE OF THE INVENTION According to this invention, the laminated body which has high insulation while having favorable heat conductivity can be provided.

It is sectional drawing which shows typically the laminated body which concerns on one Embodiment of this invention. It is sectional drawing which shows typically the laminated body which concerns on one Embodiment of this invention. 2 is a cross-sectional photograph of a resin composition layer of a laminate produced in Example 1. 2 is a cross-sectional photograph of a resin composition layer of a laminate produced in Example 2. 2 is a cross-sectional photograph of a resin composition layer of a laminate produced in Example 3. 2 is a cross-sectional photograph of a resin composition layer of a laminate produced in Comparative Example 1. 4 is a cross-sectional photograph of a resin composition layer of a laminate produced in Comparative Example 2.

The laminate of the present invention has a metal base plate, a resin composition layer containing an epoxy resin and an inorganic filler, and a metal plate in this order, and the porosity in the cross section of the resin composition layer determined from image analysis. However, the area ratio is 0.09% or less.
Here, the voids in the resin composition layer are likely to be generated near the interface between the inorganic filler and the epoxy resin. If the ratio of the voids in the resin composition layer is increased, the insulating property may be lowered even if the thermal conductivity is good. Therefore, the present inventors have found that it is important that the porosity in the cross section of the resin composition layer is 0.09% or less in terms of the area ratio as the porosity that can achieve both thermal conductivity and insulation. It was.
Therefore, if the area ratio of the porosity exceeds 0.09%, it is impossible to increase the insulation while having high thermal conductivity. The area ratio of the porosity is preferably 0.08% or less, and more preferably 0.05% or less.
Further, from the viewpoint of not peeling when warpage occurs, the area ratio of the porosity is preferably 0.00001% or more.

In order to obtain the area ratio of the porosity by image analysis, first, a cross-sectional image of the resin composition layer obtained by SEM observation is normalized using, for example, image processing software as necessary. Next, for example, after performing median filter processing, an area having a threshold value of 75 or less among 256 gradations is regarded as a gap, and a ratio of the area having a threshold value of 75 or less is obtained to obtain the area ratio of the void ratio. For filter selection for image processing, it is only necessary to clearly distinguish the contrast between the gap and other portions. For example, a known noise removal filter such as a moving average filter may be used.
The specific image analysis method is as described in the examples.

Here, in order to set the porosity to 0.09% or less in terms of area ratio, for example, in press processing performed after laminating a metal base plate, a resin composition layer, and a metal plate, a somewhat higher pressure (for example, 180 It is preferable to apply a pressure of about 8 to 25 MPa at ˜210 ° C.
It is thought that voids are likely to occur along the vicinity of the interface between the filler and the epoxy resin, but such press treatment can push out air remaining at the filler interface and suppress the generation of voids. The area ratio can be 0.09% or less. Further, when the area ratio is 0.09% or less, among the inorganic fillers present in the resin composition, an inorganic filler whose major axis direction is parallel to the thickness direction and an inorganic filler perpendicular to the thickness direction; Are mixed in a well-balanced manner, and it is presumed that the insulating properties are enhanced as well as the thermal conductivity.

Hereinafter, the resin composition layer, the metal base plate, the metal plate and the like according to the laminate of the present invention will be described.
(Resin composition layer)
The resin composition layer includes an epoxy resin and an inorganic filler. The inorganic filler preferably has thermal conductivity.

  Here, the inorganic filler preferably includes plate-like inorganic particles, and more preferably contains plate-like inorganic particles, inorganic particles A, and inorganic particles B. By including at least the plate-like inorganic particles, the plate-like inorganic particles whose major axis direction is parallel to the thickness direction and the plate-like inorganic particles whose major axis direction is perpendicular to the thickness direction are mixed in a balanced manner. Insulation can be enhanced as well as conductivity.

At least one inorganic filler has a thermal conductivity of 10 W / (m · K) or more. For example, when only the plate-like inorganic particles are included, the plate-like inorganic particles have a thermal conductivity of 10 W / (m · K) or more, and the plate-like inorganic particles, the inorganic particles A, and the inorganic particles B When three types are included, any one or more of these have a thermal conductivity of 10 W / (m · K) or more.
As described above, it is preferable that one or more of the plate-like inorganic particles, the inorganic particles A, and the inorganic particles B have a thermal conductivity of 10 W / (m · K) or more, and all are 10 W / (m · K) It is preferable to have a thermal conductivity equal to or higher than that. Thereby, the thermal conductivity of the resin composition layer can be increased. The thermal conductivity is more preferably 15 W / (m · K) or more, and further preferably 20 W / m · K (m · K) or more. The upper limit of thermal conductivity is not particularly limited. Inorganic fillers having a thermal conductivity of about 300 W / (m · K) are widely known, and inorganic fillers having a thermal conductivity of about 200 W / (m · K) are easily available.
The plate-like inorganic particles, the inorganic particles A, and the inorganic particles B are different in at least one of composition, shape, and compressive strength. For example, when the plate-like inorganic particles and the inorganic particles B are boron nitride, the shape may be different in compressive strength at the time of 20% compression, or the primary particles may have different major diameters.

  The plate-like inorganic particles are preferably boron nitride, and hexagonal boron nitride, cubic boron nitride, boron nitride prepared by a reduction nitriding method of boron compound and ammonia, and nitrogen-containing compounds such as boron compound and melamine And boron nitride prepared from sodium borohydride and ammonium chloride. From the viewpoint of more effectively increasing the thermal conductivity, the boron nitride is preferably hexagonal boron nitride.

  From the viewpoint of more effectively increasing the insulation and thermal conductivity, the plate-like inorganic particles are preferably plate-like boron nitride aggregate particles. Boron nitride aggregated particles are secondary particles obtained by aggregating primary particles of boron nitride.

  It does not specifically limit as a manufacturing method of the said boron nitride aggregate particle, A spray-drying method, a fluidized-bed granulation method, etc. are mentioned. The method for producing the boron nitride 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. From the viewpoint of more easily controlling the total pore volume, the ultrasonic nozzle method is preferable.

  The boron nitride aggregated particles are preferably produced using primary particles of boron nitride as a material. The boron nitride used as the material for 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 boron compound and ammonia, boron compound and melamine, and the like. Examples thereof include boron nitride produced from a nitrogen compound and boron nitride produced from sodium borohydride and ammonium chloride. From the viewpoint of further effectively increasing the thermal conductivity of the boron nitride aggregated particles, the boron nitride used as the material of the boron nitride aggregated particles is preferably hexagonal boron nitride.

  Moreover, as a manufacturing method of boron nitride aggregated particles, a granulation step is not necessarily required. It may be boron nitride aggregated particles formed by spontaneously concentrating boron nitride primary particles as the boron nitride crystal grows. Moreover, in order to make the particle diameter of boron nitride aggregated particles uniform, pulverized boron nitride aggregated particles may be used.

Compressive strength at 20% compression of the plate-like inorganic particles is preferably 0.8~2.5N / mm ^2, more preferably 1.0~2.0N / mm ^2. By being 0.8 to 2.5 N / mm ² , it can be easily crushed at the time of pressing, and by deforming the shape, the air present at the filler interface can be pushed out, and the insulation can be further improved. it can.
In addition, since the compressive strength of the plate-like inorganic particles is relatively small, it tends to collapse and voids are generated by the press treatment, but as described above, the porosity is kept low by performing the press treatment to some extent, Thermal conductivity and insulation can be improved.

In the present invention, the compressive strength can be measured as follows.
First, using a micro compression tester, a diamond prism is used as a compression member, the smooth end surface of the compression member is lowered toward the inorganic filler, and the inorganic filler is compressed. As a measurement result, the relationship between the compression load value and the compression displacement is obtained, and the compression load value per unit area is calculated using the average cross-sectional area calculated using the particle size of the inorganic filler. Compressive strength. Further, the compression rate is calculated from the compression displacement and the particle size of the inorganic filler, and the relationship between the compression strength and the compression rate is obtained. The inorganic filler to be measured is observed using a microscope, and an inorganic filler having a particle size of ± 10% is selected and measured. In addition, the compression strength at each compression rate is calculated as an average compression strength obtained by averaging 20 measurement results. As the micro compression tester, for example, “Micro compression tester HM2000” manufactured by Fischer Instruments is used. The compression ratio can be calculated by (compression ratio = compression displacement / average particle diameter × 100).

  The aspect ratio of the plate-like inorganic particles is preferably 3 or more, and more preferably 4-6. By being 3 or more, the long diameter of the primary particle | grains of the aggregation boron nitride becomes long, and heat conductivity can be maintained.

  Further, in the primary particles of the plate-like inorganic particles, the average major axis, which is the average of the major axis, is preferably 2.5 to 30.0 μm, and preferably 5 to 20 μm from the viewpoint of suitably increasing the thermal conductivity. It is more preferable. The average major axis refers to the average of 100 major axes determined in the aspect ratio measurement described above.

  In the present invention, the aspect ratio means a major axis / minor axis. In the present specification, the aspect ratio is an average aspect ratio. Specifically, 50 arbitrarily selected particles are observed with an electron microscope or an optical microscope, and the average value of the major axis / minor axis of each particle is calculated. It is obtained by calculating.

  From the viewpoint of further effectively increasing the insulation and thermal conductivity, the average particle size of the plate-like inorganic particles is preferably 5 to 100 μm, and more preferably 20 to 80 μm.

  In the present invention, the average particle size is preferably an average particle size obtained by averaging the particle sizes on a volume basis. The average particle diameter can be measured using a “laser diffraction particle size distribution analyzer” manufactured by Horiba, Ltd. About the calculation method of an average particle diameter, it is preferable to employ | adopt the particle diameter (d50) of an inorganic filler when a cumulative volume is 50% as an average particle diameter.

  Examples of the inorganic particles A include alumina, synthetic magnesite, silica, aluminum nitride, silicon nitride, silicon carbide, zinc oxide, magnesium oxide, talc, mica, and hydrotalcite. Of these, alumina (particularly, spherical alumina, crushed alumina) and spherical aluminum nitride are preferable, and spherical alumina is more preferable. By using these, heat dissipation can be further enhanced.

  The aspect ratio of the inorganic particles A is preferably 2 or less, and more preferably 0.1 to 1.9. When the aspect ratio is 2 or less, it becomes easy to rotate at the time of coating and can enter the gap between the inorganic particles B and the plate-like inorganic particles.

  From the viewpoint of further effectively increasing the insulation and thermal conductivity, the average particle size of the inorganic particles A is preferably 0.1 to 20 μm, and more preferably 0.3 to 18 μm.

  The inorganic particles B are preferably boron nitride, and hexagonal boron nitride, cubic boron nitride, boron nitride prepared by a reduction nitriding method of a boron compound and ammonia, a boron compound and a nitrogen-containing compound such as melamine, and the like. And boron nitride prepared from sodium borohydride and ammonium chloride. From the viewpoint of more effectively increasing the thermal conductivity, the boron nitride is preferably hexagonal boron nitride.

  From the viewpoint of further effectively increasing the insulation and thermal conductivity, the inorganic particles B are preferably boron nitride aggregated particles. The boron nitride aggregated particles are the same as the plate-like inorganic particles.

  The aspect ratio of the inorganic particles B is preferably 3 or more, more preferably 4 to 10. By being 3 or more, the long diameter of the primary particle | grains of the aggregation boron nitride becomes long, and heat conductivity can be maintained.

  In addition, the average major axis of the primary particles of the inorganic particles B is preferably 0.5 to 15 μm and preferably 0.8 to 13 μm from the viewpoint of improving the filling property and suitably improving the thermal conductivity. Is more preferable.

Compressive strength at 20% compression of the inorganic particles B is preferably 2~15N / mm ^2, more preferably 2.5~13N / mm ^2. By being 2-15N / mm < ² >, a shape can be maintained without crushing at the time of a press, and heat conductivity can be maintained.

  From the viewpoint of further effectively increasing the insulation and thermal conductivity, the average particle diameter of the inorganic particles B is preferably 20 to 90 μm, and more preferably 30 to 70 μm.

The content of the plate-like inorganic particles in the inorganic filler is preferably 1 to 100% by volume, more preferably 3 to 90% by volume, and further preferably 30 to 90% by volume. By being 1-100 volume%, heat conductivity can be raised efficiently. Moreover, it is preferable that content of the inorganic particle A in an inorganic filler is 1-50 volume%, and it is more preferable that it is 3-45 volume%. Furthermore, the content of the inorganic particles B in the inorganic filler is preferably 1 to 90% by volume, and more preferably 3 to 85% by volume.
Moreover, it is preferable that content of the inorganic filler in a resin composition layer is 20-90 volume%, and it is more preferable that it is 30-80 volume%.

The compressive strength at 20% compression of the inorganic particles B is larger than that of the plate-like inorganic particles, and is preferably 1.5 N / mm ² or more.

The epoxy resin is obtained by reacting an epoxy compound with a thermosetting agent.
Epoxy compounds include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, phenol novolac type epoxy compounds, biphenyl type epoxy compounds, biphenyl novolac type epoxy compounds, biphenol type epoxy compounds, naphthalene type epoxy compounds, Fluorene type epoxy compound, phenol aralkyl type epoxy compound, naphthol aralkyl type epoxy compound, dicyclopentadiene type epoxy compound, anthracene type epoxy compound, epoxy compound having adamantane skeleton, epoxy compound having tricyclodecane skeleton, naphthylene ether type epoxy Examples thereof include an epoxy compound having a compound and a triazine nucleus in the skeleton.
The epoxy compound is preferably a bisphenol A type epoxy compound.

  The thermosetting agent is not particularly limited as long as it has a functional group capable of reacting with the epoxy group of the above epoxy compound. Cyanate ester compound (cyanate ester curing agent), phenol compound (phenol thermosetting agent), amine compound (Amine thermosetting agent), thiol compound (thiol thermosetting agent), imidazole compound, phosphine compound, acid anhydride, active ester compound, dicyandiamide and the like.

  Examples of the cyanate ester compound include novolak type cyanate ester resins, bisphenol type cyanate ester resins, and prepolymers in which these are partially trimerized. As said novolak-type cyanate ester resin, a phenol novolak-type cyanate ester resin, an alkylphenol-type cyanate ester resin, etc. are mentioned. Examples of the bisphenol type cyanate ester resin include bisphenol A type cyanate ester resin, bisphenol E type cyanate ester resin, and tetramethylbisphenol F type cyanate ester resin.

  Commercially available products of cyanate ester compounds include phenol novolac-type cyanate ester resins (Lonza Japan “PT-30” and “PT-60”), and prepolymers (Lonza Japan Ltd.) in which bisphenol-type cyanate ester resins are trimerized. “BA-230S”, “BA-3000S”, “BTP-1000S”, and “BTP-6020S”) and the like.

  Examples of the phenol compound include novolak type phenol, biphenol type phenol, naphthalene type phenol, dicyclopentadiene type phenol, aralkyl type phenol, dicyclopentadiene type phenol and the like.

  Examples of commercially available phenolic compounds include novolak-type phenols (“TD-2091” manufactured by DIC), biphenyl novolac-type phenols (“MEHC-7851” manufactured by Meiwa Kasei Co., Ltd.), and aralkyl-type phenol compounds (“MEH-” manufactured by Meiwa Kasei Co., Ltd.). 7800 "), and phenols having an aminotriazine skeleton (" LA1356 "and" LA3018-50P "manufactured by DIC).

  Although the compounding quantity of the thermosetting agent for making it react with an epoxy compound is selected suitably, Preferably it is 1 mass part or more with respect to 100 mass parts of epoxy compounds, More preferably, it is a mass part or more, Preferably it is 50 mass. Part or less, more preferably 30 parts by weight or less.

  The epoxy resin obtained by reacting the epoxy compound with the thermosetting agent is preferably contained in the resin composition layer in an amount of 5 to 80% by volume, and more preferably 10 to 70% by volume. By containing 5-80 volume%, adhesiveness and insulation can be improved more effectively.

The resin composition layer may contain other components such as a dispersant, a chelating agent, and an antioxidant in addition to the components described above.
The resin composition layer is formed by semi-curing or curing a resin composition containing the inorganic filler, epoxy compound, thermosetting agent and the like. This resin composition can contain a solvent from the viewpoint of adjusting its viscosity. The solvent is not particularly limited, and examples thereof include toluene and methyl ethyl ketone. These can be used alone or in combination of two or more.

(Metal base plate or metal plate)
Since the metal base plate and the metal plate each function as a heat conductor, the thermal conductivity is preferably 10 W / (m · K) or more. Examples of materials used for these include aluminum, copper, gold, silver, and graphite sheets. From the viewpoint of more effectively increasing the thermal conductivity, aluminum, copper, or gold is preferable, and aluminum or copper is more preferable.

  The thickness of the metal base plate is preferably 0.1 to 5 mm, and the thickness of the metal plate is preferably 10 to 900 μm. The metal plate includes a plate such as a copper plate and a foil such as a copper foil.

The layered product of the present invention may have a single resin composition layer, or may have at least two resin composition layers such as a first resin layer and a second resin layer. As shown in FIG. 1, the resin composition layer having one layer includes a structure including one resin composition layer 14 between the metal plate 12 and the metal base plate 16.
In this case, the thickness of the resin composition layer is preferably 30 to 300 mm, and more preferably 50 to 280 mm.

  Further, as shown in FIG. 2, the resin composition layer has two layers, as shown in FIG. 2, between the metal plate 22 and the metal base plate 26, the resin composition layer 24A (first resin layer) from the metal base plate 26 side. And the structure containing the resin composition layer 24 which has the resin composition layer 24B (2nd resin layer) in this order is mentioned. By adopting a structure of at least two layers, each layer can be given a function according to the application.

When the resin composition layer has a two-layer structure, the resin composition layer 24A may include plate-like inorganic particles, and the resin composition layer 24B may include inorganic particles A and inorganic particles B, or a resin The composition layer 24A may include inorganic particles A and inorganic particles B, and the resin composition layer 24B may include plate-like inorganic particles.
Preferably, the resin composition layer 24A contains a plate-like inorganic particle, and more preferably, the resin composition layer 24A contains a plate-like inorganic particle, and the resin composition layer 24B contains the inorganic particle A and inorganic particles. A configuration in which the particles B are contained is mentioned.
When the plate-like inorganic particles and the inorganic particles B are boron nitride aggregated particles, the inorganic particles A are alumina particles, and the 20% compressive strength of the plate-like inorganic particles is lower than the 20% compressive strength of the inorganic particles B, the thermal conductivity In addition, the adhesion between the metal plate 22 and the resin composition layer 24B can be improved while making the insulation better.

  In the case where the resin composition layer 24A contains plate-like inorganic particles and the resin composition layer 24B contains inorganic particles A and inorganic particles B, the content of the plate-like inorganic particles in the resin composition layer 24A is as follows. 3 to 90% by volume, and preferably 5 to 85% by volume. At this time, it is preferable that an epoxy resin is 5-60 volume%, and it is preferable that it is 10-50 volume%.

  Moreover, it is preferable that it is 1-60 volume%, and, as for content of the inorganic particle A in the resin composition layer 24B, it is preferable that it is 3-50 volume%. The content of the inorganic particles B is preferably 1 to 90% by volume, and preferably 3 to 85% by volume. At this time, it is preferable that an epoxy resin is 5-60 volume%, and it is preferable that it is 10-50 volume%.

Further, in the configuration in which the resin composition layer 24A contains the plate-like inorganic particles, it is preferable to further contain the inorganic particles A. As the plate-like inorganic particles and the inorganic particles A coexist in the resin composition layer 24A, the progress of voids (cracks) generated between the plate-like inorganic particles and the plate-like inorganic particles stops at the inorganic particles A, and as a result As a result, the porosity can be further reduced.
The volume ratio between the plate-like inorganic particles and the inorganic particles A at this time is preferably 1 to 30 and more preferably 2 to 25 when calculated as plate-like inorganic particles / inorganic particles A.

  In addition, even when the resin composition layer has a two-layer structure, the total content in each layer of the inorganic filler including the plate-like inorganic particles, the inorganic particles A, and the inorganic particles B, and the total content in each layer of the epoxy resin Is the same as in the case of a single resin composition layer.

When the resin composition layer has a two-layer configuration, the thickness of the resin composition layer 24A on the metal base plate side is preferably 20 to 170 mm, and more preferably 50 to 150 mm. The thickness of the resin composition layer 24B on the metal plate side is preferably 10 to 150 mm, and more preferably 20 to 130 mm.
In addition, when the resin composition layer has a two-layer structure, the total thickness of each layer is the same as that in the case where the resin composition layer is one layer, and is preferably 30 to 320 mm. More preferably, it is 280 mm.

When the resin composition layer has a single layer structure, the laminate is, for example, coated with a resin composition on a metal base plate, semi-cured as necessary, and then bonded to the metal plate to a certain degree. (For example, a pressure of about 8 to 25 MPa at 180 to 210 ° C.) can be performed. Moreover, it can also manufacture by pinching both surfaces of the sheet | seat which consists of resin compositions with a metal base plate and a metal plate, respectively, and performing the said press process.
Further, when the resin composition layer has a two-layer structure, the laminate is, for example, coated with a resin composition to be the first resin composition layer on a metal base plate and semi-cured as necessary. After that, a resin composition to be the second resin composition layer is further applied thereon and semi-cured as necessary. Then, it can manufacture by bonding a metal plate and performing the said press process. In addition, both sides of the laminated sheet of the sheet made of the resin composition to be the first resin composition layer and the sheet made of the resin composition to be the second resin composition layer are sandwiched between the metal base plate and the metal plate, respectively. It can also be manufactured by performing the above-mentioned press treatment.

  The laminated body of the present invention as described above is used in, for example, a heat radiator disposed between a heat generating component and a heat radiating component in an electronic device and installed between a CPU and a fin, or an inverter of an electric vehicle. It is used as a heat sink for power cards. Moreover, it can use as an insulating circuit board | substrate by forming a circuit in the technique of etching etc. about the metal plate of the laminated body of this invention.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention more concretely, this invention is not limited to these.

(Preparation of resin composition)
(1) Resin composition A:
Aggregated boron nitride particles (UHP-G1H, manufactured by Showa Denko KK) 38.3% by volume, alumina particles (AS50, manufactured by Showa Denko KK) 24.9% by volume, epoxy compound (YD127, manufactured by Nippon Steel & Sumikin Co., Ltd.) 33.2% by volume %, A curing agent (2P4MZ, manufactured by Shikoku Kasei Co., Ltd.) 2.0% by volume, and a dispersant (KBM403, manufactured by Shin-Etsu Silicone Co., Ltd.) 1.6% by volume were mixed to obtain a resin composition A. The 20% compressive strength of the aggregated boron nitride particles was 4.2 N / mm ² . The aspect ratio of the alumina particles was 2.
(2) Resin composition B:
Aggregated boron nitride particles (HP-40, manufactured by Mizushima Gosei Co., Ltd., 20% compressive strength 1.7 N / mm ² ) 67.5% by volume, epoxy compound (YD127, manufactured by Nippon Steel & Sumikin Co., Ltd.) 29.3% by volume, A resin composition B was obtained by mixing to be 2.0% by volume of a curing agent (2P4MZ, manufactured by Shikoku Kasei Co., Ltd.) and 1.2% by volume of a dispersant (KBM403, manufactured by Shin-Etsu Silicone).
(3) Resin composition C:
Aggregated boron nitride particles (HP-40, manufactured by Mizushima Gosei Co., Ltd.) 64.7% by volume, alumina (AS50, manufactured by Showa Denko) 5.0% by volume, epoxy compound (YD127, manufactured by Nippon Steel & Sumikin Co., Ltd.) 27. 2% by volume, dispersion material (KBM403, manufactured by New Silicone Co., Ltd.) 1.4% by volume, and curing agent (2P4MZ, manufactured by Shikoku Kasei Co., Ltd.) 1.7% by volume were mixed to obtain a resin composition C. .

[Example 1]
The resin composition A was applied on a release PET sheet (thickness 40 μm) so as to have a thickness of 80 μm. Moreover, the resin composition B was apply | coated so that it might become thickness 300 micrometers on a release PET sheet (thickness 40 micrometers). These were dried in a 50 ° C. oven for 10 minutes and temporarily cured. Next, the pre-cured sheet is laminated so that the release PET sheet is on the outside, and then the release PET sheet is peeled off, and both sides are copper foil (thickness 40 μm) and an aluminum plate (thickness 1.0 mm). And heated at 110 ° C. for 30 minutes for temporary curing to obtain a pre-cured sheet. A layer containing the resin composition A (second resin composition layer) is formed on the copper foil side, and a layer containing the resin composition B (first resin composition layer) is formed on the aluminum plate side. Has been.

  The obtained uncured sheet was vacuum-pressed for 60 minutes under the conditions of a temperature of 195 ° C. and a pressure of 8 MPa to obtain a laminate (thermal conductive sheet).

[Example 2]
A laminate (heat conductive sheet) was obtained in the same manner as in Example 1 except that the resin composition C was used instead of the resin composition B. In the laminate, a layer containing the resin composition A (second resin composition layer) is formed on the copper foil side, and a layer containing the resin composition C (first resin composition) on the aluminum plate side. Layer) is formed.

[Example 3]
A laminate (thermal conductive sheet) was obtained in the same manner as in Example 1 except that the resin composition C was used in place of the resin composition B and the pressure was pressed under the condition of 13 MPa. In the laminate, a layer containing the resin composition A (second resin composition layer) is formed on the copper foil side, and a layer containing the resin composition C (first resin composition) on the aluminum plate side. Layer) is formed.

[Comparative Example 1]
A laminate (thermal conductive sheet) was obtained in the same manner as in Example 1 except that the pressure during the vacuum pressing was changed from 8 MPa to 4 MPa.

[Comparative Example 2]
A laminate (thermal conductive sheet) was obtained in the same manner as in Example 1 except that the pressure during the vacuum pressing was changed from 8 MPa to 6 MPa.

(Cross section observation: porosity)
Each laminate of Examples and Comparative Examples was held at 285 ° C. for 5 minutes, then cut to 10 × 10 mm, and the cross section of the obtained sample was smoothed with abrasive paper, and a cross section polisher (manufactured by JEOL Ltd.) The observation surface was produced by “IB-19520CCP”). After that, the observation surface obtained by sputtering the cross section with Pt ion sputtering (E-1045, manufactured by Hitachi High-Technologies) was magnified 500 times and Pixel Size 198 so that the entire sheet could enter using a scanning electron microscope (SEM). To obtain a cross-sectional image. Cross-sectional photographs of Examples 1 and 2 and Comparative Examples 1 and 2 are shown in FIGS. In any of the cross-sectional photographs, the upper side was the copper foil side, the lower side was the aluminum plate side, and voids were confirmed in the first resin composition layer on the aluminum plate side.

  Image processing and analysis were performed on this image. By performing median filter processing (1 pixel) with “Avizo 9.2” (manufactured by Thermo Fisher Scientific), an area having a threshold value of 75 or less of 256 gradations is regarded as a crack, and a ratio of the area having a threshold value of 75 or less is obtained. The void area ratio was determined. The results are shown in Table 1 below.

[Evaluation]
(Measurement of thermal conductivity)
After cutting each laminated body of an Example and a comparative example into 1 cm square, the measurement of the measurement of thermal conductivity was performed by the laser flash method using the measurement sample which sprayed carbon black on both surfaces. The results are shown in Table 1 below.

(BDV measurement)
Each laminated body of an Example and a comparative example was cut out to the magnitude | size of 100x100 mm, and the sample was obtained. The obtained sample was etched to produce a patterned electrode on the copper foil side, and then held in a 50 ° C. oven for 60 minutes to obtain a test sample. After holding at 285 ° C. for 5 minutes, an AC voltage was applied between the test samples using a withstand voltage tester (“MODEL7473” manufactured by EXTECH Electronics) so that the voltage increased at a rate of 0.5 kV / min. . The voltage at which the test sample was broken was defined as a dielectric breakdown voltage (BDV). The results are shown in Table 1 below.

12 Metal plate 16 Metal base plate 14 Resin composition layer

Claims (11)

A laminate having a metal base plate, a resin composition layer containing an epoxy resin and an inorganic filler, and a metal plate in this order,
A laminate in which the void ratio in the cross section of the resin composition layer obtained from image analysis is 0.09% or less in terms of area ratio.   The laminate according to claim 1, wherein the inorganic filler includes plate-like inorganic particles having a thermal conductivity of 10 W / (m · K) or more. The inorganic filler includes plate-like inorganic particles, inorganic particles A, and inorganic particles B,
The laminate according to claim 1, wherein any one or more of the plate-like inorganic particles, the inorganic particles A, and the inorganic particles B have a thermal conductivity of 10 W / (m · K) or more.   The laminate according to claim 3, wherein the inorganic particles A have an aspect ratio of 2 or less.   The laminate according to any one of claims 2 to 4, wherein a content of the plate-like inorganic particles in the inorganic filler is 30 to 100% by volume.   The laminate according to any one of claims 2 to 5, wherein the plate-like inorganic particles are boron nitride.   The laminate according to any one of claims 2 to 6, wherein the plate-like inorganic particles are aggregated particles.   The laminate according to any one of claims 3 to 7, wherein the inorganic particles B have a compressive strength at 20% compression that is greater than that of the plate-like inorganic particles.   The laminate according to any one of claims 3 to 8, wherein the inorganic particles B are boron nitride. The resin composition layer consists of at least two layers, and has a first resin composition layer and a second resin composition layer in this order from the metal base plate side,
The first resin composition layer includes the plate-like inorganic particles;
The laminate according to any one of claims 3 to 9, wherein the second resin composition layer contains the inorganic particles A and the inorganic particles B.   The laminate according to claim 10, wherein the first resin composition layer further contains the inorganic particles A.