TW201902696A - Laminate for circuit boards, metal base circuit board and power module - Google Patents

Abstract

Provided is a laminate for circuit boards, which comprises a metal substrate, an insulating layer that is provided on at least one surface of the metal substrate, and a metal foil that is provided on the insulating layer. The insulating layer contains a resin component and an inorganic filler; and the resin component has a phase separation structure that comprises a discontinuous phase containing a thermosetting resin and a continuous phase containing a rubber.

Description

Multilayer board for circuit board, metal base circuit board and power module

FIELD OF THE INVENTION The present invention relates to a laminated board for a circuit board, a metal base circuit board produced from the laminated board for the circuit board, and a power module including the metal base circuit board.

Background Art In recent years, the development of electronic technology has been astounding, and the high performance and miniaturization of motor electronic instruments have progressed rapidly. Along with this, the metal base circuit board corresponding to the high-density mounting used in these has been increased in size and increased in density. Therefore, various performance improvements are required for the metal base circuit substrate, and extensive efforts are being made in response to expectations.

Heretofore, a resin composition using an epoxy resin has been widely used as a resin composition used in an insulating layer constituting a metal base circuit substrate. For example, Japanese Laid-Open Patent Publication No. 2007-254709 discloses a resin composition in which a specific phenol-based curing agent, a phenoxy resin, and rubber particles are added to a composition containing an epoxy resin, and A resin composition of an insulating layer having a small thickness on the surface of the insulating layer and a high adhesion strength to the interface of the conductor layer. Further, Japanese Laid-Open Patent Publication No. 2009/119598 discloses a resin composition in which a specific phenoxy resin or a cyanate resin is added to a composition containing an epoxy resin, in addition to plating adhesion. Improve heat resistance and moisture resistance reliability.

SUMMARY OF THE INVENTION With the rapid development of the high performance and miniaturization of the above-described motor electronic devices, the amount of heat generated by the components to which the motor components and/or electronic components are mounted is increasing. Therefore, it is required to further improve the workability and the water absorption resistance and the oxidation deterioration resistance under high temperature moisture absorption conditions in accordance with the high-density mounting of the metal base circuit substrate.

An object of the present invention is to provide a laminated board for a circuit board which is excellent in workability and is excellent in water absorption resistance and oxidation deterioration resistance under high temperature moisture absorption conditions, a metal base circuit board produced from the laminated board for a circuit board, and the like. A power module of a metal base circuit substrate.

According to an aspect of the present invention, a laminated board for a circuit board can be provided, comprising: a metal substrate; an insulating layer disposed on at least one side of the metal substrate; and a metal foil disposed on the insulating layer; The insulating layer contains a resin component and an inorganic filler, and the resin component has a phase separation structure including a discontinuous phase containing a thermosetting resin and a continuous phase containing rubber.

According to another aspect of the invention, the laminated board for a circuit board contains at least a rubber having a weight average molecular weight of 1.5 million or less as the rubber.

Further, according to another aspect, the laminated board for a circuit board contains at least a rubber having a saturated structure in the main chain as the rubber.

Further, according to another aspect, the laminated board for a circuit board contains at least an acrylic rubber as the rubber.

Further, according to another aspect, the laminated board for a circuit board has a blending ratio of the rubber in the insulating layer of 1 to 40% by mass based on the total mass of the resin component.

Further, according to another aspect, the laminated board for a circuit board contains at least a cyanate resin as the thermosetting resin.

In addition, the laminated board for a circuit board contains the bisphenol type cyanate resin and the novolak type cyanate resin as the said thermosetting resin.

In addition, the blending ratio of the laminated board for a circuit board as the epoxy resin of the thermosetting resin is 0 to 10% by mass based on the total mass of the thermosetting resin.

Moreover, according to another aspect of the present invention, a metal base circuit board can be obtained by patterning the metal foil provided in any one of the circuit board laminates.

Furthermore, according to another aspect of the present invention, a power module including the above-described metal base circuit substrate can be provided.

According to the present invention, it is possible to provide a laminated board for a circuit board which is excellent in workability and is excellent in water absorption resistance and oxidative deterioration resistance under high temperature moisture absorption conditions, a metal base circuit board manufactured from the laminated board for circuit board, and the like A power module of a metal base circuit substrate.

Embodiments for Carrying Out the Invention Hereinafter, embodiments of the present invention will be described in detail. A laminated board for a circuit board according to an embodiment of the present invention includes a metal substrate, an insulating layer provided on at least one surface of the metal substrate, and a metal foil provided on the insulating layer. The laminated board 1 for a circuit board shown in FIG. 2 and FIG. 3 has a three-layer structure in which an insulating layer 3 is formed on one surface of the metal substrate 2, and a metal foil 4 is formed on the insulating layer 3. In another embodiment of the present invention, the laminated board for a circuit board may have a five-layer structure in which an insulating layer 3 is formed on both surfaces of the metal substrate 2, and a metal foil 4 is formed on each insulating layer 3. In FIGS. 2 and 3, the X and Y directions are parallel to the main surface of the metal substrate 2 and perpendicular to each other, and the Z direction is a thickness direction perpendicular to the X and Y directions. In FIG. 2, a laminated board 1 for a circuit board on a rectangular shape is shown as an example, and the laminated board 1 for circuit boards may have another shape.

The insulating layer provided in the laminated board for a circuit board of the embodiment is a cured product using a coating film formed of a resin composition, and the resin composition contains at least a resin component and an inorganic filler. The insulating layer contains at least a thermosetting resin and rubber as a resin component.

The resin component forms a phase separation structure in the insulating layer. The phase separation structure is a sea-island structure in which a discontinuous phase is dispersed in a continuous phase (matrix), the discontinuous phase contains a thermosetting resin, and the continuous phase contains rubber. Accordingly, in one embodiment, one of the characteristics of the insulating layer is that it has a phase separation structure in which rubber is not dispersed in a matrix in a discontinuous phase, but rubber constitutes a continuous phase (matrix), and the thermosetting resin is discontinuous. The phase (dispersion phase) is dispersed in the continuous phase. Hereinafter, a phase separation structure having a continuous phase containing rubber and a discontinuous phase containing a thermosetting resin contained in the insulating layer is referred to as a phase separation structure of the present invention.

Although rubber is low in water absorbability, even if rubber is dispersed in a matrix which constitutes an insulating layer in a discontinuous phase (dispersion phase), low water absorption which is desired as a metal base circuit substrate cannot be obtained. By forming the continuous phase (matrix) of the rubber in the insulating layer, the effect of suppressing water absorption in the insulating layer can be exhibited, and the low water absorption in the metal base circuit substrate can be improved. Further, since the oxygen permeability of the rubber is also low, the rubber constitutes the continuous phase and contributes to the improvement of the oxidation deterioration resistance in the metal base circuit substrate.

The soft rubber is compatible with the thermosetting resin to improve the workability, and the phase separation structure is formed by hardening, and the mechanical strength or stress relaxation of the insulating layer is improved.

The presence or absence of the phase separation structure of the present invention in the insulating layer can be confirmed, for example, by microscopic observation and/or scattering measurement. In the case of microscopic observation, the phase separation structure can be confirmed by a scanning electron microscope (SEM), an atomic force microscope, an optical microscope, a transmission electron microscope, or the like. Further, in the case of scattering measurement, phase separation structure can be confirmed by small angle incident small angle X-ray scattering measurement, elemental analysis, energy dispersive X-ray analysis, electron probe microanalyzer, X-ray photoelectron spectroscopy, and the like. Whether there is.

Further, the presence or absence of the phase separation structure of the present invention in the insulating layer can be confirmed by DMA measurement (dynamic viscoelasticity measurement). When the blending ratio of the rubber in the resin component is not high, the method for confirming the phase-separated structure of the present invention measured by the DMA is a particularly effective method. For example, when the blending ratio of the rubber is usually less than 50% by mass, preferably 40% by mass or less, relative to the total mass of the resin component, it becomes a particularly effective method. That is, in the case of the phase separation structure of the present invention in which the rubber forms the continuous phase, even if the blend ratio of the rubber is small, the peak derived from the rubber can be clearly observed by DMA measurement. On the other hand, in the case of a reverse phase separation structure in which a rubber forms a discontinuous phase like rubber particles, if the blending ratio of the rubber is not high, the peak from the rubber cannot be detected by the DMA measurement. It is assumed that this is because in the case of a reverse phase separation structure in which the rubber forms a discontinuous phase, if the rubber blending ratio is small, the effect of the resin is dominant, and it is difficult to observe the peak from the rubber by DMA measurement.

Hereinafter, the phase separation structure of the present invention will be described using the photographs shown in Figs. 1A to 1E. Here, the photographs shown in FIGS. 1A to 1E are photographs of those in which the insulating layer is cut and mechanically polished. Fig. 1A is a scanning electron microscope (SEM) photograph showing an example of a phase separation structure of the present invention. In order to explain the phase separation structure of the present invention in an easily understandable manner, the phase separation structure shown in Fig. 1A does not contain an inorganic filler. In the phase separation structure shown in Fig. 1A, the thermosetting resin 102 of a discontinuous phase (dispersion phase) is dispersed in the rubber 101 of the continuous phase. By thus, the rubber constitutes a continuous phase, and as described above, the low water absorbability and the oxidation deterioration resistance are improved.

On the other hand, the SEM photograph of FIG. 1D shows a phase separation structure (hereinafter referred to as "reverse phase separation structure" or the like) which is opposite to the phase separation structure of the present invention. In the reverse phase separation structure shown in Fig. 1D, the rubber particles 112 of the discontinuous phase (dispersion phase) are dispersed in the thermosetting resin 111 of the continuous phase. In such a reverse phase separation structure, even if a rubber component is contained, the above effects cannot be obtained.

Fig. 1B is an optical micrograph showing an example of a structure in which an inorganic filler is dispersed in the phase separation structure of the present invention. Here, two kinds of inorganic fillers 103a and 103b are used as the inorganic filler. The inorganic filler 103a is aluminum nitride, and the strip-shaped inorganic filler 103b surrounded by a solid line is boron nitride. From the photograph, the phase separation structure of the present invention can be confirmed from the gap or void of the inorganic fillers 103a, 103b. For example, when the inside of the broken line frame A is viewed, it is confirmed that the thermosetting resin 102 of the discontinuous phase (dispersion phase) is dispersed in the rubber 101 of the continuous phase in the void of the inorganic filler (aluminum nitride) 103a. Fig. 1C is an optical microscope photograph without a rubber system with respect to the phase separation structure shown in Fig. 1B. In the structure shown in FIG. 1C, an inorganic filler (aluminum nitride) 123a and a strip-shaped inorganic filler (boron nitride) 123b surrounded by a solid line are dispersed in the continuous phase thermosetting resin 121. When the inside of the broken line frame A' is viewed, it is understood that the void of the inorganic filler (aluminum nitride) 123a is filled only by the thermosetting resin 121.

1E is an SEM photograph showing an example of a structure in which an inorganic filler is dispersed with respect to FIG. 1D showing a reverse phase separation structure. Here, in the continuous phase thermosetting resin 111, two kinds of inorganic fillers, that is, an inorganic filler (alumina) 113a and a strip-shaped inorganic filler (boron nitride) 113b surrounded by a broken line and rubber are dispersed. Particle 112. It is understood that the rubber particles 112 are not uniformly dispersed in the gap between the two inorganic fillers (alumina) 113a and the inorganic filler (boron nitride) 113b. The rubber to be used in the present invention may be any polymer material having rubber elasticity at normal temperature, and may be, for example, a modulus of elasticity of 100 MPa or less at normal temperature (for example, 25 ° C).

In the insulating layer, in order to form the phase-separated structure of the present invention, it is preferred that the resin composition for the insulating layer before curing be in a state in which the rubber and the thermosetting resin are dissolved in a solvent and uniformly dispersed. When the thermosetting resin is cured by heating in this state, the molecular weight of the thermosetting resin locally increases and the viscosity increases, and finally the viscosity is high (hard) to the rubber. From the viewpoint of viscosity, the lower viscosity component forms a continuous phase, and therefore, the phase separation structure of the present invention having a continuous phase containing rubber and a discontinuous phase containing a thermosetting resin can be formed.

Therefore, from the viewpoint of solubility in a solvent, the weight average molecular weight of the rubber is preferably 1.5,000,000 or less, preferably 1.3 million or less, more preferably 900,000 or less. The lower limit of the weight average molecular weight of the rubber is not particularly limited, and is, for example, preferably 50,000 or more. Here, the weight average molecular weight represents a polystyrene-converted value measured by a GPC (gel permeation chromatography) method.

Examples of the rubber which can be suitably used in the embodiment are as follows. That is, a diene rubber such as styrene butadiene rubber, isoprene rubber, butadiene rubber, chloroprene rubber or acrylonitrile butadiene rubber; butyl rubber or ethylene propylene rubber; Non-diene rubber such as ethylene propylene diene rubber, urethane rubber, polyoxyethylene rubber, fluororubber, chlorosulfonated polyethylene rubber, chlorinated polyethylene, acrylic rubber, polysulfide rubber or epichlorohydrin rubber; A thermoplastic elastomer such as styrene, olefin, ester, urethane, guanamine, polyvinyl chloride (PVC) or fluorine; or natural rubber.

In an embodiment of the invention, the main chain of the rubber is preferably a saturated structure. Here, the main chain is a saturated structure means a structure in which a polymer main chain does not have a double bond or a triple bond unsaturated bond in a bond of carbon atoms to each other.

Examples of the rubber whose main chain is a saturated structure include butyl rubber, ethylene propylene rubber, ethylene propylene diene rubber, urethane rubber, polyoxyethylene rubber, fluororubber, chlorosulfonated polyethylene rubber, and chlorinated polyethylene. Non-diene rubber such as acrylic rubber, polysulfide rubber or epichlorohydrin rubber; or thermoplastic elastomer such as styrene, olefin, ester, urethane, guanamine, PVC or fluorine. Body and so on. In one embodiment, an acrylic rubber is particularly preferred. The insulating layer may contain one type of rubber alone or two or more types.

Examples of the thermosetting resin constituting the discontinuous phase include cyanate resin, epoxy resin, phenol resin, urea resin, melamine resin, acrylic resin, urethane resin, maleic imine resin, and benzo. Resin, polyimine resin, polyamidimide resin, unsaturated polyester resin, oxime resin, diallyl phthalate resin, alkyd resin, and the like. The thermosetting resin may be used alone or in combination of two or more.

In the embodiment of the present invention, the thermosetting resin is particularly preferably a cyanate resin. Examples of the cyanate resin include a bisphenol type cyanate resin and a novolak type cyanate resin. Examples of the bisphenol-type cyanate resin include a bisphenol A type cyanate resin, a bisphenol E type phenol resin, and a tetramethyl bisphenol F type cyanate resin. The weight average molecular weight of the bisphenol type cyanate resin is not particularly limited and may be an oligomer or a monomer. For example, from the viewpoint of heat resistance, the order of tetramethyl bisphenol F type cyanate resin, bisphenol A type cyanate resin, and bisphenol E type cyanate resin is preferable. From the viewpoint of reactivity, a bisphenol A type cyanate resin is preferred.

In one embodiment of the present invention, a thermosetting resin is preferably a mixed system of a bisphenol-type cyanate resin and a novolak-type cyanate resin. The ratio is preferably, for example, a mass ratio of bisphenol type cyanate resin: novolac type cyanate resin of from 11:1 to 1:1, and more preferably from 9:1 to 2:1.

Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, and three Type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolak type epoxy resin, O-cresol novolak type epoxy resin, biphenyl novolac type epoxy resin, triphenylmethane type epoxy resin, dicyclopentadiene type epoxy resin, alicyclic epoxy resin, brominated epoxy resin An epoxy resin having two or more epoxy groups in the same molecule.

However, in the embodiment of the present invention, when the epoxy resin is not contained or the epoxy resin is contained, the content thereof is preferably a predetermined amount or less with respect to the total mass of the thermosetting resin. For example, the content of the epoxy resin is preferably from 0 to 10% by mass, more preferably from 0 to 7% by mass, even more preferably from 0 to 5% by mass, based on the total mass of the thermosetting resin.

As described above, the resin component of the insulating layer has a phase separation structure composed of a discontinuous phase containing a thermosetting resin and a continuous phase containing rubber, and if it is exothermic, blending of a continuous phase containing rubber The ratio is preferably lower than the blend ratio of the discontinuous phase containing the thermosetting resin. In one embodiment, the rubber blending ratio is preferably in the range of 1 to 40% by mass based on the total mass of the resin component, more preferably 5 to 30% by mass, still more preferably 5 to 20% by mass.

In the embodiment, the insulating layer contains an inorganic filler together with the resin component. Examples of the inorganic filler include alumina, aluminum nitride, boron nitride, tantalum nitride, magnesium oxide, and cerium oxide. One or two or more selected from the group consisting of these are preferably used. The inorganic filler is present in the resin component without distinction between the discontinuous phase and the continuous phase. That is, the inorganic filler may be present in the discontinuous phase, may be present in the continuous phase, or may be present in both. Further, the inorganic filler may exist across the discontinuous phase and the continuous phase.

In a system containing an inorganic filler, there is a tendency that the exothermic reaction accompanying hardening is suppressed by the presence of the inorganic filler. Specifically, in consideration of the fact that the reaction heat is absorbed by the inorganic filler, the curing reaction is slow, or the surface functional group of the inorganic filler hinders the curing reaction of the thermosetting resin. Therefore, a surface-treated inorganic filler can also be used, and an inorganic filler is preferably used in an appropriate combination with an effect accelerator described later. As the surface treatment of the inorganic filler, for example, the surface of the inorganic filler may be modified by a functional group which may be chemically bonded to react with the thermosetting resin, or may be compatible with the thermosetting resin. High functional groups for modification (eg cyanate groups, epoxy groups, amine groups, hydroxyl groups, carboxyl groups, vinyl groups, styryl groups, methacrylic groups, acrylic groups, urea groups, mercapto groups, sulfur groups, isocyanate groups) Etc.), for example, decane coupling treatment or plasma treatment can be used.

In the embodiment, the ratio of the inorganic filler contained in the insulating layer is preferably from 50 to 90% by volume based on the total volume of the resin components. The content of the inorganic filler is more preferably 60 to 80% by volume. If the filling rate is too low, the desired thermal conductivity cannot be obtained, and there is a tendency for the inorganic filler to precipitate. On the other hand, if the filling ratio is too high, the viscosity becomes too high to obtain a uniform coating film, which may cause an increase in pore defects.

The insulating layer may also contain a hardening accelerator. The hardening accelerator is not particularly limited, and for example, benzo Compound, borate complex, zinc naphthenate, cobalt naphthenate, tin octoate, cobalt octoate, cobalt (II) acetoacetate, cobalt (III) such as triethyl hydrazine, phenol, bisphenol A, phenolic compounds such as nonylphenol.

Benzo The compound has at least one benzoic acid in the molecule The ring can be. Benzo The compound may be a monomer or a polymer which is polymerized to form an oligomer state. In one embodiment, benzo The compound preferably has two or more benzo groups in the molecule. The monomer of the ring. Also, it is also possible to simultaneously use a plurality of benzenes having different structures. Compound.

Benzo The compound may, for example, be a Pd-type benzoate. Bisphenol F type benzo Fa type benzo Etc. Among them, it should be Pd-type benzo . Pd type benzo a rigid skeleton having a diphenylmethylene skeleton, and thus, a derivative compound thereof is derived, for example, from a Ba-type benzene The compound can form a crosslinked structure with better thermal properties.

The borate complex may be a phosphorus borate complex or a non-phosphorus borate complex. Examples of the phosphorus-based borate complex compound include, for example, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-toluate borate, tris-tert-butylphosphonium tetraphenylborate, and di-tertiary butylmethyl group. Panthene tetraphenylborate, p-tolyltriphenylphosphonium tetra-p-toluene borate, tetraphenylphosphonium tetrafluoroborate, triphenylphosphine triphenylborate, and the like.

Examples of the non-phosphorus borate complex may be, for example, sodium tetraphenylborate, pyridine triphenyl borate, 2-ethyl-4-methylimidazolium tetraphenylborate, 1,5-diazabicyclo[4.3. 0] terpene-5-tetraphenylborate, lithium triphenyl(n-butyl)borate, and the like.

In the embodiment, when a hardening accelerator is added to the insulating layer, the content ratio thereof can be appropriately set. For example, when the hardening accelerator uses benzo In the case of the compound, the content of the thermosetting resin is preferably from 1 to 20% by mass, and more preferably from 5 to 15% by mass, based on the total mass of the thermosetting resin.

In an embodiment, the insulating layer may further contain other components. Examples of other components which may be contained in the insulating layer include a coupling agent such as a decane coupling agent and a titanium coupling agent, an ion adsorbent, an anti-settling agent, an anti-hydrolysis agent, a leveling agent, an antioxidant, and the like.

The insulating layer is a cured product of a coating film formed of a resin composition, and the resin composition contains at least the above resin component and an inorganic filler. As described above, in order to form the phase-separated structure of the present invention, the resin composition preferably constitutes a state in which the rubber and the thermosetting resin are uniformly dispersed in each other. Therefore, it is preferred to contain a solvent which can dissolve the rubber and the resin. Examples of such a solvent include amide-based solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide, and N-methyl-2-pyrrolidone (NMP). , an ether solvent such as 1-methoxy-2-propanol or ethylene glycol monomethyl ether, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclohexanone, cyclopentanone A ketone solvent, an aromatic solvent such as toluene or xylene, or the like. One type of solvent may be used alone or two or more types may be used in combination.

The coating film (for example, a dried film) before the formation of the phase separation structure of the present invention preferably constitutes a state in which the rubber and the thermosetting resin are uniformly dispersed in each other, and therefore has high flexibility and excellent workability. Therefore, the insulating layer having the phase separation structure of the present invention formed by the compatibility state of such a rubber and a thermosetting resin has excellent workability.

In the laminated board for a circuit board of the embodiment, the metal substrate is made of, for example, a single metal or an alloy. The material of the metal substrate can be, for example, aluminum, iron, copper, aluminum alloy or stainless steel. The metal substrate may further contain a non-metal such as carbon. For example, the metal substrate 2 may also contain aluminum that has been compounded with carbon. Further, the metal substrate may have a single layer structure or a multilayer structure.

The metal substrate has high thermal conductivity. Typically, the metal substrate 2 has a thermal conductivity of 60 W·m ^-1 ·K ^-1 or more. The metal substrate may or may not be flexible. The thickness of the metal substrate is, for example, in the range of 0.2 to 5 mm.

The metal foil is disposed on the insulating layer. The metal foil sandwiches the insulating layer and faces the metal substrate. The metal foil is composed of, for example, a single metal or an alloy. As the material of the metal foil, for example, copper or aluminum can be used. The thickness of the metal foil is, for example, in the range of 10 to 500 μm.

The laminate for a circuit board of the embodiment can be produced, for example, by the following method. First, the resin composition is applied to at least one of a metal substrate and a metal foil. The coating of the resin composition can be carried out, for example, by a roll coating method, a bar coating method or a screen printing method. This can be done in a continuous manner or by a single board.

After drying the coating film as needed, the metal substrate and the metal foil are laminated so as to face each other with the coating film interposed therebetween. Furthermore, these are subjected to hot pressing. According to the above, a laminate for a circuit board can be obtained.

In this method, a coating film is formed by applying a resin composition to at least one of a metal plate and a metal foil. However, in other aspects, the dispersion may be applied to a substrate such as a PET film. The coating film is formed in advance and dried, and is thermally transferred to one of a metal substrate and a metal foil.

Next, a metal base circuit board produced by the above laminated board for a circuit board will be described. An embodiment of a metal base circuit substrate is shown in FIG. The metal base circuit board 1' shown in Fig. 4 is obtained from the laminated board 1 for circuit boards shown in Figs. 2 and 3, and includes a metal substrate 2, an insulating layer 3, and a circuit pattern 4'. The circuit pattern 4' is obtained by patterning the metal foil 4 of the laminated board for a circuit board described with reference to Figs. 2 and 3. This patterning can be obtained, for example, by forming a mask pattern on the metal foil 4 and removing the exposed portion of the metal foil 4 by etching. The metal base circuit board 1' can be obtained by, for example, patterning the metal foil 4 of the conventional circuit board laminate 1 and performing processing such as cutting and punching as necessary.

Since the metal base circuit board of the embodiment is obtained from the above-mentioned laminated board for a circuit board, it is excellent in low water absorbability, workability, and oxidation deterioration resistance.

A power module of an embodiment is shown in FIG. Since the power module 100 includes the metal base circuit board 13 according to the embodiment of the present invention including the metal substrate 13c, the insulating layer 13b, and the circuit pattern 13a, it is excellent in low water absorption, workability, and oxidation deterioration resistance. In the current situation in which the heat generation temperature tends to increase as the power element is improved in performance, the module of the present invention can also be suitably applied to a temperature zone that cannot be accommodated in a conventional power module.

In addition, compared with the conventional power module 200 shown in FIG. 6, the power module 100 of the embodiment has a reduced number of constituent members (layers) due to the metal base circuit board 13, and the entire thickness is reduced. Lower thermal resistance and miniaturized design. Moreover, since processing such as piercing and cutting is easy, it is also advantageous in that assembly is easy.

EXAMPLES Hereinafter, examples of the present invention will be described. The invention is not limited to the ones. <Preparation of Composition> Synthesis Examples 1 to 6: Preparation of Resin Compositions 1 to 6 A bisphenol-type cyanate resin (hereinafter also referred to as "B-type cyanate resin") (trade name "BA200"; Japan Longsha (LONZA) Co., Ltd.) and a novolac type cyanate resin (hereinafter also referred to as "N-type cyanate resin") (trade name "PT30"; manufactured by Japan Longsha (LONZA) Co., Ltd.) The mixture was mixed to form a B-type cyanate resin in a mass ratio: N-type cyanate resin = 9:1. The Pd-type benzophenone represented by the following formula is added to 100 parts by mass of the mixture of the cyanate resin obtained. Compound (trade name "Pd type benzophenone" 10 parts by mass of a hardening accelerator was stirred at 100 ° C until the mixture became homogeneous, and was solubilized by a solvent methyl ethyl ketone (MEK).

In the obtained resin solution, the rubber (the acrylate copolymer in which the polymer main chain is saturated) is 1, 5, 10, 20, 30 with respect to 100 parts by mass of the entire resin component (including the rubber). 40 parts by mass, and a mixture of 1:1 (mass ratio) of aluminum nitride (AlN) and boron nitride (BN) as a filler (inorganic filler), which is 65 vol% in total with respect to the entire resin component Dispersion, thereby modulating the resin compositions 1 to 6.

[Chemical Formula 1]

Synthesis Example 7: Preparation of Resin Composition 1R A B-type cyanate resin (trade name "BA200"; manufactured by Japan Longsa (LONZA) Co., Ltd.) and N-type cyanate resin (trade name "PT30"; Japan) Lonza (manufactured by LONZA Co., Ltd.), mixed to form a B-type cyanate resin in a mass ratio: N-type cyanate resin = 9:1. The Pd-type benzoic acid represented by the above formula is added to 100 parts by mass of the mixture of the cyanate resin obtained. Compound (trade name "Pd type benzophenone" 10 parts by mass of a curing accelerator was added at 100 ° C until the mixture became homogeneous, and was dissolved in a solvent ethylene glycol monomethyl ether.

In the obtained resin solution, a mixture of 1:1 (mass ratio) of aluminum nitride (AlN) and boron nitride (BN) is dispersed so as to be 65 vol% in total with respect to the entire resin component. The resin composition 1R was prepared.

Synthesis Example 8: Preparation of the resin composition 2R: 10 parts by mass of a phenoxy resin (trade name "YP-500"; manufactured by Nippon Steel & Sumitomo Chemical Co., Ltd.) was added in an amount of 90 parts by mass based on the mixture of the cyanate resin. The resin composition 2R was prepared by the same method as the resin composition 1R except that it was mixed until it became uniform.

Synthesis Example 9: Preparation of the composition 3R 10 parts by mass of acryl rubber particles (trade name "UNI-POWDER"; manufactured by JX Energy Co., Ltd.) was added to 90 parts by mass of the mixture of the cyanate resin and mixed. The resin composition 3R was prepared by the same method as the resin composition 1R except that it was uniform.

The obtained resin compositions 1 to 6, 1R to 3R are shown in Table 1. Further, the weight average molecular weight of the rubber is a value in terms of polystyrene measured by a GPC method.

[Table 1]

<Manufacturing of laminated board> Each of the resin compositions prepared as described above was applied to a copper foil for a circuit, and the thickness after heating and pressurization was 100 μm. Next, after drying the solvent, it is bonded to the copper plate constituting the base, and is subjected to heat and pressure molding to form a laminate.

<Confirmation of Phase Separation Structure> The cross section of the insulating layer was observed by a scanning electron microscope, thereby confirming the presence or absence of the phase separation structure of the present invention in the insulating layer.

As a result, in the insulating layers (Examples 1 to 6) using any one of the resin compositions 1 to 6, the same phase separation structure as that of FIG. 1B was confirmed. On the other hand, in the insulating layer (Comparative Example 1 and Comparative Example 2) using the resin composition 1R or 2R, the phase separation structure could not be confirmed. Further, in the insulating layer (Comparative Example 3) using the resin composition 3R, the same phase separation structure (reverse phase separation structure) as that of Fig. 1E was confirmed.

Further, the presence or absence of the phase-separated structure of the present invention in the insulating layer can be confirmed by an analysis method using DMA measurement. In the DMA measurement, the copper foil for the circuit and the base copper plate were removed from each of the laminates by etching, and the obtained insulating layer was cut into a thin rectangular shape having a width of 3 mm and a length of 50 mm as a sample. The measurement conditions were carried out at a temperature of 5 ° C / min from -50 ° C to 350 ° C, and the measurement was carried out at a frequency of 1 Hz in a tensile mode. The ratio of the storage modulus to the loss modulus obtained here is set to tan δ.

7A is a graph showing the characteristics of tan δ obtained by DMA measurement for the insulating layer using the resin composition 3 (Example 3), and FIG. 7B is a graph showing the insulating layer for the resin composition 3R (Comparative) Example 3) The characteristics of tan δ obtained by DMA measurement.

In the graph shown in FIG. 7A, peak T detected from a thermosetting resin (cyanate ester resin) of _a rubber from the peak T _2, may be that the phase separation structure of the present invention. On the other hand, in the graph shown in FIG. 7B, since the peak derived from the rubber was not detected, the added acrylic rubber particles did not form a continuous phase, but showed a dispersed state in a discontinuous phase, and it was found that the particles were not formed. The phase separation structure of the present invention.

In the DMA measurement for the insulating layers (Examples 1, 2, 4 to 6) using any of the resin compositions 1, 2, 4 to 6, the same as in Fig. 7A, the thermosetting resin was detected ( peak cyanate resin) T ₁ of the rubber from the peak T _2, confirmed that the phase separation structure of the present invention.

The phase-separated structure in which the present invention was formed was set to A, and the unformed one was set to B, and the results are shown in Table 2.

<Evaluation> The workability, water absorption, water absorption solder withstand voltage, and heat resistant adhesion were evaluated by the methods shown below. The results are shown in Table 2. Further, the water absorption rate is small and the water absorption solder withstand voltage is larger, indicating that the water absorption is more excellent. Further, the greater the heat resistance adhesion force, the more excellent the oxidation resistance deterioration resistance.

[Processability] The workability is obtained by visually observing the presence or absence of a coating film notch when the dried film is cut by shearing, and the dried film is applied to a copper foil for a circuit and dried. form. The dry film was not set to A, and the dried film was notched to B, and the results are shown in Table 2. Further, it was found that the dry film was excellent in the workability without being nicked, and further, it was found that the workability was also excellent in the insulating layer which was cured. [Water absorption ratio (% by mass)] After the copper foil for the circuit and the base copper plate were removed from each of the laminates by etching, the water absorption ratio was measured by the following method for the obtained insulating layer.

After drying at a temperature of 100 ° C for 24 hours, the quality of the insulating layer was measured. Then, after absorbing moisture for 24 hours under the conditions of a temperature of 85 ° C and a humidity of 85%, the quality of the insulating layer was measured again. The mass increase rate before and after moisture absorption was calculated and set as the water absorption rate.

[Water-absorbing solder withstand voltage (kV)] The copper foil surface of the circuit for each laminated board was etched, and a circuit pattern of Φ20 mm was formed. The circuit pattern of Φ20 mm was allowed to absorb water for 24 hours under an ambient gas of 98% at 40 °C. Next, after floating in a solder bath of 280 ° C for 5 minutes, the breakdown voltage was measured by the following method, whereby the water absorption solder withstand voltage was obtained.

An withstand voltage was measured by applying an alternating voltage to the insulating oil between the circuit pattern of Φ20 mm and the copper plate on the back side. The voltage was increased from the initial voltage of 500 V each time, and each time the voltage was applied for 20 seconds, the operation was repeated, and the voltage was gradually increased, and the breakdown voltage was measured.

[Heat Resistance Adhesion (MPa)] The copper foil surface of the circuit for each laminated board was etched, and a circuit pattern of Φ4 mm was formed. In the atmospheric environment, after the circuit pattern was placed at 200 ° C for 1000 hours, the vertical peeling strength of the circuit pattern was measured by the following method, whereby heat-resistant adhesion was obtained.

A stud pin with an epoxy adhesive was vertically fixed on a circuit pattern of Φ 4 mm, and heated at 150 ° C for 1 hour, thereby hardening it, and a tensile test sample was prepared. Next, the sample was fixed to a tensile tester, and the stud pin was pulled in the vertical direction, and the contact force was calculated from the load and the contact area at the time of peeling off from the circuit pattern, whereby the vertical peeling strength of the circuit pattern was measured.

[Table 2]

As is clear from Table 2, Examples 1 to 6 of the embodiment of the present invention are excellent in workability. Further, it is found that Examples 1 to 6 of the embodiment of the present invention have a small water absorption rate and a large water-resistant solder withstand voltage, and therefore, are excellent in low water absorption. Further, it can be seen that Examples 1 to 6 of the embodiment of the present invention have a large heat-resistance adhesion force, and therefore are excellent in oxidation deterioration resistance.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit and scope of the invention. Further, each embodiment can be implemented as appropriate as possible, and the effect of the combination can be obtained. Furthermore, the above-described embodiments include various stages of the invention, and various inventions can be proposed by appropriate combinations of the plurality of constituent elements disclosed. For example, even if several constituent elements are deleted from the entire constituent elements shown in the embodiment, the problem described in the column to be solved by the invention can be solved, and when the effect described in the effect field of the invention can be obtained, the composition is deleted. The structure of the requirements can be proposed as an invention.

1‧‧‧Laminated boards for circuit boards

1', 13‧‧‧ metal base circuit substrate

2, 13c, 27‧‧‧ metal substrate

3, 13b‧‧‧ insulation

4‧‧‧metal foil

4', 13a, 23‧‧‧ circuit patterns

11, 21‧‧‧ Power components

12‧‧‧ solder layer

14, 28‧‧ ‧ heat release film

15, 29‧‧‧ Heat sink

22‧‧‧First solder layer

24‧‧‧Ceramic substrate

25‧‧‧metallization

26‧‧‧Second solder layer

100‧‧‧Power Module

101‧‧‧Continuous phase (rubber)

102‧‧‧ discontinuous phase (thermosetting resin)

103a, 123a‧‧‧Inorganic filler (aluminum nitride)

103b, 113b, 123b‧‧‧Inorganic filler (boron nitride)

111, 121‧‧‧Continuous phase (thermosetting resin)

112‧‧‧ discontinuous phase (rubber particles)

113a‧‧Inorganic filler (alumina)

200‧‧‧Knowledge Power Module

A, A’‧‧‧ dotted box

Fig. 1A is a SEM photograph showing an example of a phase separation structure composed of a rubber of a continuous phase and a thermosetting resin of a discontinuous phase. Fig. 1B is an optical micrograph showing an example of a structure in which an inorganic filler is dispersed in a phase separation structure composed of a rubber of a continuous phase and a thermosetting resin of a discontinuous phase. Fig. 1C is an optical micrograph showing an example of a structure in which an inorganic filler is dispersed in a thermosetting resin in a continuous phase. Fig. 1D is a SEM photograph showing an example of a phase separation structure composed of a thermosetting resin of a continuous phase and rubber particles of a discontinuous phase. Fig. 1E is a SEM photograph showing an example of a structure in which an inorganic filler is dispersed in a phase separation structure composed of a thermosetting resin of a continuous phase and rubber particles of a discontinuous phase. FIG. 2 is a perspective view schematically showing a laminated board for a circuit board according to an embodiment of the present invention. Fig. 3 is a cross-sectional view taken along line II-II of the laminated board for circuit board shown in Fig. 2; 4 is a cross-sectional view schematically showing an example of a metal base circuit substrate obtained by laminating sheets for circuit boards shown in FIGS. 2 and 3. Fig. 5 is a cross-sectional view schematically showing a power module according to an embodiment of the present invention. Figure 6 is a cross-sectional view schematically showing a conventional power module. FIG. 7A is a graph showing the characteristics of tan δ obtained by DMA measurement of the insulating layer contained in the laminated body for a circuit board of Example 3. FIG. FIG. 7B is a graph showing the characteristics of tan δ obtained by DMA measurement of the insulating layer contained in the laminated body for a circuit board of Comparative Example 3.

Claims (10)

A laminated board for a circuit board, comprising: a metal substrate; an insulating layer provided on at least one surface of the metal substrate; and a metal foil provided on the insulating layer; wherein the insulating layer contains a resin component and an inorganic filler; Further, the resin component has a phase separation structure including a discontinuous phase containing a thermosetting resin and a continuous phase containing rubber. The laminate for a circuit board according to claim 1, wherein the rubber contains at least a rubber having a weight average molecular weight of 1.5 million or less. The laminate for a circuit board according to claim 1, wherein the rubber contains at least a rubber having a saturated structure in the main chain. A laminate for a circuit board according to claim 1, wherein the rubber contains at least an acrylic rubber. The laminate for a circuit board according to claim 1, wherein a blending ratio of the rubber in the insulating layer is 1 to 40% by mass based on the total mass of the resin component. The laminate for a circuit board according to claim 1, wherein the thermosetting resin contains at least a cyanate resin. The laminate for a circuit board according to claim 1, wherein the thermosetting resin contains a bisphenol type cyanate resin and a novolac type cyanate resin. The laminate for a circuit board according to claim 1, wherein a blending ratio of the epoxy resin as the thermosetting resin is from 0 to 10% by mass based on the total mass of the thermosetting resin. A metal base circuit board is obtained by patterning the metal foil provided in the laminated board for a circuit board according to any one of claims 1 to 8. A power module comprising the metal base circuit substrate of claim 9.