JP5396721B2 - Thermally conductive cured product, heat dissipation substrate using the same, and manufacturing method thereof - Google Patents

Description

The present invention relates to a heat-conductive material cured product used for various electronic components that require heat dissipation, such as power semiconductors, high-performance semiconductors, and light-emitting elements whose heat generation density is improved for downsizing of electronic devices, and The present invention relates to a heat dissipation board using the same and a manufacturing method thereof.

  Conventionally, as a heat dissipation substrate for mounting electronic components, a metal core substrate in which an insulating material layer is laminated on a metal plate to form a wiring pattern is often used. Next, a conventional metal core substrate will be described with reference to FIG.

  FIG. 5 is a cross-sectional view of a conventional heat dissipation substrate. In FIG. 5, an electrical insulating layer 2 is formed on the metal plate 1. A copper foil 3 is laminated on the electrical insulating layer 2. On top of this, the electronic component 5, the semiconductor 6, the terminal 7, etc. are mounted using the solder 4. Here, the higher the thermal conductivity of the electrical insulating layer 2, the more heat from the electronic component 5 and the semiconductor 6 can be transmitted to the metal plate 1, and the temperature rise can be suppressed. As the electrical insulating layer 2, a mixture of resin and filler is often used.

  As a method for increasing the thermal conductivity, a method of using a material having a high thermal conductivity as the filler of the electrical insulating layer 2 or a method of improving the filling amount of the filler is often used. Further, increasing the thermal conductivity of the resin is also effective and will be described with reference to FIG. For example, it has been proposed to use a crystalline resin as a means for increasing the thermal conductivity of the resin.

  FIG. 6 is a schematic view of a change during a polymerization reaction of a monomer having a mesogenic group. As shown in FIGS. 6A to 6C, the monomers 9 having mesogenic groups 8 are intended to obtain electrical insulation and excellent thermal conductivity by polymerizing each other. However, in order to obtain high heat dissipation (or high thermal conductivity) using a crystalline resin, it is necessary to increase the crystallization rate of the crystalline resin. However, in the crystalline resin, the higher the crystallization rate, the more difficult the problem is that the resulting substrate is hard and brittle (breaks without bending or is easily cracked or cracked). In addition, the resin itself is easy to burn, and it is difficult to impart flame retardancy to the substrate while maintaining the crystallinity. Therefore, even if a heat dissipation substrate for mounting electronic components is produced using a crystalline resin, Usage was greatly limited.

As prior art document information related to the invention of this application, for example, Patent Document 1 and Patent Document 2 are known.
Japanese Patent No. 3255315 JP-A-11-323162

  As described above, the conventional crystalline resin has limited properties for the heat dissipation substrate due to the characteristic properties of the crystalline resin (hard and brittle, easy to chip, easy to break, easy to burn, etc.).

  As a method of improving the strength, there is a method of blending a curing agent that easily takes a network structure, etc., but in the case of a crystalline epoxy resin, by creating a three-dimensional bond, the crystallinity is inhibited and high thermal conductivity is obtained. In many cases, it cannot be obtained.

  Furthermore, the crystalline resin has weak adhesion to a metal plate or the like (or stress is likely to concentrate inside the crystallized resin or at the interface between the crystallized resin and the metal plate, and this stress causes the interface between the crystallized resin and the metal plate to be concentrated. Therefore, when a heat dissipation board is manufactured, there may be a problem in impact resistance such as a drop test.

  As a method for loading the flame retardancy, a method of converting an organic flame retardant or an inorganic flame retardant can be considered. However, when an organic flame retardant is blended with structurally different resins, crystallization is inhibited and the amount of addition is limited, so that flame retardancy cannot be achieved while maintaining crystallinity. In addition, in the case of an inorganic flame retardant, since the thermal conductivity of the flame retardant is low, a high thermal conductivity cannot be obtained if the amount is increased.

The present invention solves the conventional problems, solves the problem that the crystalline resin is hard and brittle, and easily burns, and achieves both high thermal conductivity and robustness to the heat dissipation substrate using the crystalline resin, It aims at providing the heat conductive hardened | cured material which can provide a flame retardance, a heat dissipation board using the same, and its manufacturing method.

In order to solve the conventional problems, the present invention relates to a total of an epoxy resin containing 40 vol% or more of a crystalline epoxy resin having the following structural formula , a curing agent, and the epoxy resin and the curing agent. 3 vol% or more and 12 vol% or less brominated epoxy resin, 0.3 vol% or more and 2.5 vol% or less core-shell type acrylic resin with respect to the total of the epoxy resin and the curing agent, the epoxy resin and the Consists of at least one selected from alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, magnesium oxide, and zinc oxide in an amount of 70 vol% to 88 vol% with respect to the total of the curing agent and the brominated epoxy resin. an inorganic filler, 0.6 vol% or more 2.5 vol% or less of water relative to the total of the epoxy resin and the curing agent Compounds, boron compounds, antimony compounds, molybdenum compounds, a thermal conductive cured product comprising a cured product of the thermally conductive material having a flame-retardant auxiliary filler consisting of at least one kind selected from metal oxide salt The cured epoxy resin obtained by reacting the epoxy resin and the curing agent has crystallinity, and after flame contact for 10 seconds, the flame is extinguished and the combustion time (t1) until extinction is measured. After flame contact, the flame is burned out and the combustion time (t2) until extinguishing is measured. Both t1 and t2 are 10 seconds or less, and cracks and cracks occur even if they fall naturally on the concrete from a height of 1.5 m. The heat conductive cured product is characterized by not being generated .

  In this way, the flame retardant epoxy and the flame retardant auxiliary filler are similarly converted at a rate that does not cause crystallization to break down. Is to improve.

According to the thermally conductive cured product of the present invention and the heat dissipation substrate using the heat conductive substrate and the method for manufacturing the heat dissipation substrate, the high heat dissipation substrate using the crystalline resin as one component thereof is required to be strong as a component mounting substrate ( Imparts high thermal conductivity and flame resistance. As a result, the heat dissipation substrate can achieve both high heat dissipation and durability / flame resistance.

  And since it becomes difficult for stress to concentrate on a heat conductive material (or heat conductive insulating layer formed by hardening a heat conductive material), the adhesive force between the metal plate is also improved.

(Embodiment)
Hereinafter, the thermally conductive cured product and the heat dissipation substrate using the same in the embodiment of the present invention will be described. First, a heat dissipation board using the heat conductive material (or heat conductive resin) of the present invention will be described with reference to FIG.

  FIG. 1 is a cutaway view of a heat dissipation board in the embodiment. In FIG. 1, reference numeral 10 denotes a wiring pattern, which corresponds to a lead frame, copper foil or the like processed into a predetermined shape (or a predetermined wiring pattern shape). Reference numeral 11 denotes a heat conductive insulating layer, which will be described later with reference to FIG. 3 and the like (referred to as a heat conductive material 17 in FIG. 3). The heat conductive material forming the heat conductive insulating layer 11 includes a crystalline epoxy resin, a curing agent, a flame retardant epoxy resin, a thermoplastic resin, an inorganic filler, and a flame retardant auxiliary filler. Consists of a thermally conductive material. Then, this heat conductive material is processed into a sheet shape to form a heat conductive insulating layer 11. A metal plate 12 is made of a metal material having excellent thermal conductivity such as copper or aluminum.

  In FIG. 1, a sheet-like thermally conductive insulating layer 11 in which a part or more of the wiring pattern 10 is embedded is fixed to the surface of the metal plate 12. Then, one surface of the wiring pattern 10 is exposed from the thermally conductive insulating layer 11. Then, an electronic component (not shown) is mounted on the exposed surface of the wiring pattern 10 in which a part or more is embedded in the heat conductive insulating layer 11.

  Next, the heat dissipation mechanism of the heat dissipation substrate of FIG. 1 will be described with reference to FIG. 2A and 2B are cross-sectional views illustrating the heat dissipation mechanism of the heat dissipation board in which the wiring pattern 10 is embedded. 2A and 2B, reference numeral 13 denotes an electronic component, which is a semiconductor that generates heat (for example, a power transistor or a power FET), a light emitting diode (LED), or the like. 14a and 14b are arrows.

  First, as shown in FIG. 2A, the electronic component 13 is mounted on the wiring pattern 10. 2A and 2B, the solder resist formed on the wiring pattern 10 is not shown (It is desirable to form a solder resist on the wiring pattern 10. This is because the solder resist is formed on the wiring pattern 10. By forming the solder resist, mounting solder (not shown) is prevented from spreading on the surface of the wiring pattern 10).

  Next, how the heat generated in the electronic component 13 mounted on the wiring pattern 10 is radiated will be described with reference to FIG. In FIG. 2B, an arrow 14b indicates a direction in which heat is transmitted (or radiated). The heat generated in the electronic component 13 spreads over a wide area (heat spread) through the wiring pattern 10 as indicated by the arrow 14b. The heat of the wiring pattern 10 is transmitted to the heat conductive resin layer 11 in which the wiring pattern 10 is partially embedded. The heat of the heat conductive insulating layer 11 is transmitted to the metal substrate 12. In this way, the electronic component 13 is cooled. In addition, by fixing the metal plate 12 to a housing or chassis (both not shown) of the device, heat transmitted to the metal plate 12 is transmitted to the outside.

  By cooling the electronic component 13 in this way, it is possible to increase the efficiency of the electronic component 13 (for example, increase the amount of light in the case of an LED, increase the efficiency or reduce the size of the power supply circuit), increase the lifetime, and increase the reliability. 2A and 2B, a mounting portion (for example, solder, wire, bump for surface mounting, etc.) between the electronic component 13 and the wiring pattern 10 is not shown. Next, the thermally conductive material used for the heat dissipation substrate will be described.

  First, a crystalline epoxy resin, a curing agent, a flame retardant epoxy resin, a thermoplastic resin, an inorganic filler, and a flame retardant auxiliary filler are weighed and mixed according to the blending ratio.

  As the mixing device, a commercially available heat kneading device (for example, a planetary mixer or kneader, or a laboratory plast mill manufactured by Toyo Seiki Seisakusho Co., Ltd.) or a twin screw kneader is used. Note that a stirring blade of Σ type, Z type, hybrid type or the like may be attached as a stirring blade inside the kneading apparatus. Moreover, shapes other than a blade | wing can also be used. Further, it is desirable to use a kneading apparatus that can be heated to a predetermined temperature with a heater or the like. By heating the kneading apparatus, the resin material that is in a solid state at room temperature can be dissolved (or liquefied), so that the affinity with other members can be increased.

  Here, as the inorganic filler, it is desirable to use at least one inorganic filler selected from alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, magnesium oxide, and zinc oxide. By using such an inorganic filler having a high thermal conductivity, the thermal conductivity of the thermal conductive insulating layer 11 can be further increased. By setting the temperature of the crystalline epoxy resin within the melting temperature (for example, 50 to 200 ° C.), the melt viscosity of the crystalline epoxy resin can be kept low and the inorganic filler can be uniformly dispersed in the resin. .

  It is desirable that the temperature be higher than the minimum liquefaction temperature of these members (minimum temperature at which the liquefied state can be maintained, for example, 100 ° C. or higher). And it is easy to make it uniform by kneading above this minimum liquefaction temperature.

  When the curing accelerator is added, the temperature of the kneading apparatus (or the resin member set therein) is lowered one step so that the thermosetting reaction (or change with time) of the resin after the addition can be suppressed. In this way, a heat conductive material is produced.

  Moreover, other additives can be added as needed. For example, release agents such as plasticizers, acid amides, esters, paraffins, stress relieving agents such as nitrile rubber and butadiene rubber, organic flame retardants such as phosphate esters and melamine, antimony pentoxide, molybdenum oxide, boric acid Inorganic flame retardants such as zinc, tin oxide, barium metaborate, aluminum hydroxide, magnesium hydroxide, calcium aluminate, silane coupling agents, titanate coupling agents, coupling agents such as aluminum coupling agents, Colorants such as dyes and pigments, inorganic fibers such as glass fibers, boron fibers, silicon carbide fibers, alumina fibers and silica alumina fibers, organic fibers such as aramid fibers, polyester fibers and cellulose fibers, oxidation stabilizers, light Stabilizer, moisture resistance improver, thixotropy imparting agent, diluent, antifoaming agent, various other It fat, tackifiers, antistatic agents, lubricants, also be incorporated an ultraviolet absorber and the like.

  Next, the preforming of the heat conductive material will be described. The heat conductive insulating material thus produced is desirably formed into a shape that is easy to form, such as a sheet shape, a round bar shape, or a pellet shape, at the same time as being taken out from the kneading apparatus. By pre-molding the heat conductive insulating material into a sheet shape, a round bar shape, a pellet shape, or the like, the handleability of the heat conductive insulating material can be improved.

  Next, with reference to FIG. 3, a pre-formation (for example, a sheet-like molding example) of the heat conductive material will be described.

  3 to 4, the sheet shape is used, but a round bar shape or a pellet shape may be used. By using a round bar shape, the surface area of the heat conductive material can be reduced, and the change with time can be suppressed. Further, it is difficult to generate an air residue (also referred to as a void) at the interface with the metal plate 12 or the like during pressing. In addition, handling property and weighing property are improved by making it into a pellet form.

  FIG. 3 is a cross-sectional view for explaining the preforming (sheet shape) of the heat conductive insulating material. In FIG. 3, 15 is a film, 16 is a molding apparatus, and 17 is a thermally conductive material. In FIG. 3, the heat conductive material 17 is composed of at least a thermoplastic resin, a crystalline epoxy resin, an inorganic filler, a curing agent, and a flame retardant epoxy resin. Then, the heat conductive material 17 is set in the molding device 16 and is driven as indicated by an arrow 14 to be preformed into a sheet shape. At this time, the film 15 is sandwiched between the heat conductive material 17 and the molding device 16, so that the surface of the processed part of the molding device 16 (for example, a rotating part of the roll, etc.) Prevent dirt. The film 15 is left as a kind of surface protecting film 15 on the surface of the heat conductive material 17 formed into a sheet.

  As the film 15, a resin film such as PET whose commercially available surface is treated with silicon, water repellent, or released can be used. The thickness of the preliminarily formed heat conductive material 17 is preferably 0.02 mm or more and 5.00 mm or less. When the thickness is 0.02 mm or less, pinholes may occur in the heat conductive resin material 21. Moreover, when the thickness exceeds 5.00 mm, the heat dissipation as a heat sink may be affected. In addition, by heating the molding part (for example, pressure roll part) of the molding apparatus 16, the moldability of the heat conductive material 17 can be improved, and the thickness variation of the completed sheet can also be reduced. Then, by leaving the film 15 as a kind of protective sheet on the surface of the heat conductive material 17 preformed into a sheet shape, it is possible to prevent dirt such as dust from adhering.

  Also, coating using a coater or an extrusion molding machine can be used.

  A solvent may be added to adjust the viscosity.

  Moreover, you may knead | mix in the state previously melt | dissolved in the solvent.

  In addition, the manufacturing method is not limited to FIG.

  Next, how a heat dissipation substrate is manufactured using the sheet-shaped heat conductive material 17 will be described with reference to FIGS. 4A and 4B are cross-sectional views illustrating an example of a method for manufacturing a heat dissipation board. 4A and 4B, 18 is a press.

  First, as shown in FIG. 4A, a heat conductive material 17 from which the film 15 has been removed in advance is set between the metal plate 12 and the wiring pattern 10. Then, the metal plate 12, the heat conductive material 17 and the wiring pattern 10 are sandwiched between forming devices (16) such as a press 18 and heated and pressed as indicated by an arrow 14. It should be noted that the anti-smudge film 15 or the like is set between the metal plate 12 and the press 18 or between the wiring pattern 10 and the press 18 so that the surface of the press 18 is not stained with the heat conductive material 17. . 4 (A) and 4 (B), a die set on the press 18 is not shown. Then, as shown by the arrow 14 in the press 18, these members are heated, pressurized and fixed at a predetermined temperature.

  Thereafter, the press 18 is pulled away in the direction of the arrow 14 as shown in FIG. Thereafter, the film 15 is peeled off. In this manner, a heat dissipation substrate (a product equivalent to FIG. 1) is produced in which the wiring pattern 10 is exposed only on one surface thereof, and is embedded in the heat conductive insulating layer 11.

  By embedding the wiring pattern 10 in the heat conductive insulating layer 11 in this way, the contact area between the wiring pattern 10 and the heat conductive insulating layer 11 can be increased, and heat dissipation is improved. Further, by embedding, an effect of reducing the thickness of the wiring pattern 10 protruding from the surface of the heat conductive insulating layer 11 can be obtained. Thus, even when a lead frame having a thickness of 0.3 mm, for example, is used as the wiring pattern 10, the protrusion amount (or step) of the wiring pattern 10 from the heat conductive insulating layer 11 is obtained by embedding it in the heat conductive insulating layer 11. Is suppressed to 50 μm or less (preferably 20 μm or less, more preferably 10 μm or less). By suppressing the protruding amount in this way, it becomes easy to form the solder resist formed on the wiring pattern 10, the thickness of the solder resist can be made thin and uniform, and the heat dissipation property of the heat dissipation substrate is improved.

  Further, by embedding a part or more of the wiring pattern 10 in the heat conductive insulating layer 11, the connection strength between the wiring pattern 10 and the heat conductive insulating layer 11 is increased. Then, the tensile strength of the wiring pattern 10 can be increased (for the method of measuring the tensile strength, a method for evaluating the tensile strength of the copper foil in the printed wiring board and the like can be referred to).

  Next, the crystalline epoxy resin which is a member constituting the heat conductive material 17 will be individually described.

  Next, the crystalline epoxy resin 18 will be described using (Chemical Formula 1) to (Chemical Formula 8).

(Chemical Formula 1) to (Chemical Formula 8) are structural formulas showing an example of a crystalline epoxy resin. In (Chemical Formula 1), X in the structural formula of the crystalline epoxy resin is S (sulfur) or O (oxygen), C (carbon), or none (short bond). R1, R2, R3, and R4 are CH ₃ , H, t-Bu, and the like. R1 to R4 may be the same. This resin having an epoxy group is also called a main agent.

  (Chemical Formula 2) shows the structural formula of the curing agent used for curing the crystalline epoxy resin. In the structural formula of (Chemical Formula 2), X is S (sulfur) O (oxygen) or a short bond. A polymer obtained by mixing the main component of (Chemical Formula 1) and the curing agent of (Chemical Formula 2) and polymerizing may also be called a crystalline epoxy resin.

The ratio between the main agent and the curing agent is calculated from the epoxy equivalent. The curing agent also acts as a curing agent for the flame retardant epoxy resin. A curing agent other than (Chemical Formula 2 ) may be used as the curing agent. As the crystalline epoxy resin, those shown in (Chemical Formula 3) to (Chemical Formula 8) can also be used. The crystalline epoxy resins represented by (Chemical Formula 3) to (Chemical Formula 8) have a melting point of about 50 to 121 ° C. and a low dissolution viscosity (for example, the viscosity at 150 ° C. is 6 to 20 mPa · s). The effect of being easy to mix and disperse is obtained.

  Next, the ratio between the crystalline epoxy resin and the epoxy resin will be described. It is desirable that the crystalline epoxy resin is contained in an amount of 40 vol% or more with respect to the epoxy resin as the main agent. When the crystalline epoxy resin is less than 40 vol%, the crystallinity is hardly expressed. Moreover, there are few crystallized parts and a sufficient effect on the thermal conductivity and the like cannot be obtained.

  Next, the ratio of the flame retardant epoxy resin to the epoxy resin and the curing agent will be described. In the crystalline epoxy resin, the structural shape is largely attributed to crystallinity, and if there are many large substituents such as Br, the crystallinity is hindered. Further, in order to impart flame retardancy, an appropriate amount of flame retardant epoxy resin is required. The amount of the flame retardant epoxy resin is desirably in the range of 3 vol% or more and 12 vol% or less with respect to the amount of the epoxy resin and the curing agent. When it is 3 vol% or less, sufficient flame retardancy cannot be imparted. Moreover, when more than 12 vol%, crystallinity does not express but heat conduction will become low. This imparting flame retardancy can be realized even when the amount of the flame retardant epoxy resin is small by combining with the flame retardant aid filler.

  Further, the flame retardant auxiliary filler is preferably 0.6 vol% or more and 2.5 vol% or less with respect to the epoxy resin and the curing agent. Since the thermal conductivity of the flame retardant aid filler is low, when it is more than 2.5 vol%, the thermal conductivity is drastically decreased. Moreover, if it is 0.6 vol% or less, flame retardancy (mixing effect with flame retardant epoxy resin and inorganic filler) cannot be imparted. As the flame retardant auxiliary filler, a hydroxyl compound, a boron compound, an antimony compound, a molybdenum compound, a metal oxide salt, or the like can be used. In particular, antimony trioxide is desirable because of its great flame retardant effect. The particle size of antimony trioxide is preferably 0.1 to 20 μm (desirably 0.3 to 10.0 μm) and smaller. If it is smaller than 0.1 μm, it is expensive and may be difficult to disperse in the heat conductive material 17. Further, when the particle diameter exceeds 20 μm, the surface of the heat conductive insulating layer 11 becomes rough, which may affect the adhesion with the wiring pattern 10 made of a lead frame or the like.

  The particle size of antimony trioxide may affect the hygroscopicity. Therefore, in the case of a heat dissipation substrate in which hygroscopicity is a problem, the smaller the particle size of antimony trioxide, the easier it is to absorb moisture. Therefore, when hygroscopicity is a problem, the particle size of antimony trioxide is desirably 0.1 μm or more. This is because fine antimony trioxide of less than 0.1 μm is highly hygroscopic.

  The particle size of antimony trioxide can be easily dispersed in an epoxy resin or the like by matching the particle size of the inorganic filler (particle size close to the inorganic filler particle size). In this case, when a plurality of inorganic fillers having different particle sizes (for example, large powder and small powder) are used in combination, small powder (for example, 0.2 to 0.6 μm) or large powder (for example, 1.0 to 10 .mu.m). 0 μm), it is desirable to have the same particle size as either one. By doing so, the dispersibility of these powders is enhanced.

  By adding a thermoplastic resin, the impact resistance of the crystalline epoxy can be improved. The addition of the thermoplastic resin is also restricted due to the structure of the crystalline epoxy resin as in the case of the flame retardant epoxy, and is also related to the amount of the flame retardant epoxy resin added. In order to realize both thermal conductivity and impact resistance, the amount of the thermoplastic resin is preferably 0.3 vol% or more and 2.5 vol% or less with respect to the total of the epoxy resin and the curing agent. As the thermoplastic resin, an acrylic resin or the like can be used. Particularly, the core-shell type acrylic resin has high impact resistance. Here, the core shell is pearl-like fine particles in which a core layer made of a thermoplastic resin such as an acrylic resin is covered with a shell layer made of another resin (for example, a glassy polymer or an epoxy resin). A multilayer structure may be used depending on the application. Dispersibility can be enhanced by using particles having a primary particle size in the range of 0.05 to 1.00 μm (preferably 0.1 to 0.5 μm). In addition, even if it comprises the secondary aggregate, it can disperse | distribute easily by using a biaxial kneader etc. This is due to the core-shell structure.

  The core is made of a thermoplastic resin having a low Tg (preferably 50 ° C. or lower, more preferably 0 ° C. or lower) made of, for example, a homopolymer or copolymer of an acrylic monomer. This is because it acts as a stress concentration point in the heat conductive material 17 or in the heat conductive insulating layer 11 to improve impact resistance and relieve stress.

  When a core-shell type polymer is used, a rubber-like resin may be used as a kind of thermoplastic resin for the core portion. In the fine particle state where the primary particle diameter is 1.00 μm or less, even if it is a rubber-like resin (for example, a crosslinked resin) or a thermoplastic resin (for example, a non-crosslinked resin), it is substantially This is to perform the same function (improvement of impact resistance and stress relaxation). For this reason, the thermoplastic resin in the present invention includes a rubber-like resin (crosslinked resin).

  Note that the shell has a high Tg (preferably 100 ° C. or higher, more preferably 150 ° C. or higher). This is for the purpose of increasing the compatibility between the particles, the compatibility with the epoxy resin (including the crystalline epoxy resin), the curing agent, and the dispersibility.

  In addition, in the ratio of the inorganic filler and the total resin (herein, the total resin means the total of the epoxy resin including the crystalline epoxy resin, the curing agent, and the flammable epoxy resin, which corresponds to the resin binder), the inorganic filler is The range of 70-88 Vol% (resin binder is 30-12 Vol%) is desirable. When the proportion of the inorganic filler is less than 70 Vol%, the thermal conductivity of the thermally conductive insulating layer 11 formed by curing the thermally conductive material 17 may be reduced. It also affects flame retardancy. Moreover, when the ratio of an inorganic filler becomes larger than 88 Vol%, the moldability of a heat conductive resin material may be affected. Here, vol% means volume%.

  As the inorganic filler, alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, magnesium oxide, zinc oxide, and the like are desirable from the viewpoint of thermal conductivity, insulation, and the like. It is also possible to combine these inorganic fillers. The average particle size of the inorganic filler 19 is preferably in the range of 0.1 μm to 100 μm. When the average particle size is 0.1 μm or less, the specific surface area becomes large, the kneading of the heat conductive material 17 becomes difficult, and the moldability of the heat conductive insulating layer 11 may be affected. On the other hand, if the thickness exceeds 100 μm, it is difficult to reduce the thickness of the thermally conductive insulating layer 11, which may affect the heat dissipation as a heat dissipation substrate and may affect the miniaturization of the product. In order to increase the filling rate of the inorganic filler 19, a plurality of kinds of inorganic fillers 19 having different particle size distributions may be selected and used in combination.

  In addition, as the wiring pattern 10, depending on the use of the heat dissipation board, when the thickness of the wiring pattern 10 requires a range of 0.002 to 0.10 mm, a copper foil is required, and a range of 0.10 to 1.00 mm is required. In this case, the lead frames can be used differently. As the lead frame member, it is desirable to use a material mainly composed of copper (for example, a material called tough pitch copper or oxygen-free copper). By mainly using copper, both high heat dissipation and low resistance can be achieved. Further, by embedding a part or more of the wiring pattern 10 in the heat conductive insulating layer 11, a step (thickness step) due to the wiring pattern 10 in the heat dissipation substrate can be reduced.

Example 1
Hereinafter, as Experiment 1, an epoxy resin containing 40 vol% or more of a crystalline epoxy resin, a curing agent, and a flame retardant epoxy resin of 3 vol% or more and 12 vol% or less with respect to the total of the epoxy resin and the curing agent; , 0.3 vol% to 2.5 vol% thermoplastic resin with respect to the epoxy resin and the curing agent, and 70 vol% to 88 vol% with respect to the epoxy resin, the curing agent, and the flame retardant epoxy. The experimental result is shown about the heat conductive material 17 which consists of an inorganic filler and the said epoxy resin and the flame retardant adjuvant filler of 0.6 vol% or more and 2.5 vol% or less with respect to the said hardening | curing agent.

  First, the results of evaluating the impact resistance will be described with reference to Table 1.

  "YL6121H" made by Japan Epoxy Resin as crystalline epoxy-containing resin, "YX4000H" as epoxy resin, 4,4'-diaminobiphenyl, 4,4'-dihydroxybiphenyl ether as curing agent, Japan as flame retardant epoxy resin Brominated epoxy “BREN-S” manufactured by Kayaku Co., Ltd., ZEON Kasei core-shell acrylate copolymer “F351” as a thermoplastic resin, alumina as an inorganic filler, and antimony trioxide as a flame retardant auxiliary filler were prepared.

  “P-200” imidazole (amine adduct) manufactured by Japan Epoxy Resin as a curing accelerator is mixed and stirred, heated to a temperature at which the epoxy resin and curing agent melt, and mixed using a biaxial kneader. did. After mixing, it was molded into a shape corresponding to various tests and heat-cured under conditions of 180 ° C. × 5 Hour.

  A sample for a drop test was produced in a shape of 100 mm × 100 mm × 1.6 mm, and freely dropped onto the concrete from a height of 1.5 m. The result was judged by whether the sample was cracked or cracked. The blending conditions of the sample were changed by changing the ratio of the crystalline epoxy resin in the epoxy resin, the filler amount, and the ratio of the thermoplastic resin.

  As the proportions of the crystalline epoxy resin and filler increase, they tend to break, and the impact resistance is improved by adding a thermoplastic resin (decreasing in thermal conductivity). Table 1 shows the results.

  Impact resistance can be improved by adding 0.3% or more of thermoplastic resin.

  The thermoplastic resin such as acrylic resin added to the heat conductive material 17 is preferably added in a state where it can be extracted with acetone or the like. This is to improve the impact resistance by dispersing (or interspersing or dispersing) such a resin that improves the impact resistance in the heat conductive resin 17 in, for example, a sea-island structure. And by setting it as such a sea island structure, it can extract with acetone etc., and it is confirmed that the thermoplastic resin is disperse | distributed by the sea island structure. In the extraction, the detection accuracy of the thermoplastic resin or the like can be increased by crushing the sample.

  When a thermoplastic resin such as an acrylic resin is present in the heat conducting material 17 in a state where it cannot be extracted (for example, reacted with an epoxy resin, dissolved in an epoxy resin, or in an epoxy resin) It is difficult to extract (dispersed in a molecular state) even using acetone or the like. And when a thermoplastic resin melt | dissolves in the heat conductive material 17 in such a state, the impact-resistant improvement effect is not acquired. This is because an interface (or stress concentration) does not occur between the epoxy resin and the thermoplastic resin.

  Since the amount of extraction depends on the state of the sample for extraction (such as the pulverized state), the trace of the ratio of the thermoplastic resin to the total resin in the sample (for example, 0.1% or more, preferably 1% or more) To do. This is because it may be difficult to determine the absolute value of the thermoplastic resin by extraction.

  Next, the results of evaluating the flame retardancy will be described with reference to Table 2.

  For flame retardant test, sample 1: 125 ± 5mm × 13 ± 0.5mm × 1.6mm, sample 2: 125 ± 5mm × 13 ± 0.5mm × 0.4mm, manufactured in the shape of UL94 Based on the flame retardancy test.

  After 10 seconds of flame contact, the flame was released and the combustion time (t1) until extinction was measured. After digestion, after 10 seconds of flame contact, the flame was released and the combustion time until extinction (t2) was measured.

  The sample was mixed under the condition that there were many flammable crystalline epoxy resins and few fillers, and the ratio of the flame retardant epoxy and the flame retardant auxiliary filler was changed.

  Addition of flame retardant epoxy and flame retardant aid filler improves flame retardancy (decreases thermal conductivity). Table 2 shows the results.

  Flame retardancy can be added when 3 vol% or more flame retardant epoxy and 0.6 vol% or more flame retardant aid filler are mixed.

  Next, an example of the result of evaluating the flame retardancy in a state where impact resistance is improved by adding a thermoplastic resin will be described with reference to Table 3.

  A sample for measuring thermal conductivity was prepared in a disk shape of φ1 / 2 inch and t1 mm, and measurement was performed using a xenon laser flash manufactured by Bruker AXS.

  The sample was mixed under the condition that there were many crystalline epoxy resins having a large thermal conductivity and a large amount of filler, and the ratio of the thermoplastic resin, the flame retardant epoxy, and the flame retardant auxiliary filler was changed. Table 3 shows the results of the thermoplastic resin.

  The thermal conductivity is reduced by adding a thermoplastic resin, and when 3% or more is added, the epoxy resin cannot take crystallinity, and the thermal conductivity is extremely lowered.

  Next, the effect of the flame retardant epoxy resin will be described with reference to Table 4.

  Table 4 shows the results of the flame-retardant epoxy resin.

  Although 3% or more flame retardant epoxy resin is necessary to add flame retardancy, the addition of flame retardant epoxy resin decreases the thermal conductivity, and when 15% or more is added, the epoxy resin is crystalline. Can not be taken, and the thermal conductivity is extremely reduced.

  Next, the effect of the flame retardant aid filler will be described with reference to Table 5.

  Table 5 shows the results of the flame retardant auxiliary filler.

  A flame retardant aid filler of 0.6% or more is necessary to add flame retardancy, but the addition of the flame retardant aid filler reduces the thermal conductivity (the amount of filler does not increase drastically). When 3% or more is added, the epoxy resin cannot take crystallinity, and the thermal conductivity is extremely lowered.

  As described above, the epoxy resin containing 40 vol% or more of the crystalline epoxy resin, the curing agent, the flame retardant epoxy resin of 3 vol% or more and 12 vol% or less with respect to the total of the epoxy resin and the curing agent, and the epoxy 0.3 vol% or more and 2.5 vol% or less thermoplastic resin with respect to the total of the resin and the curing agent, and 70 vol% or more and 88 vol% or less with respect to the total of the epoxy resin, the curing agent, and the flame retardant epoxy resin. A thermally conductive material 17 (or this heat transfer material 17) comprising an inorganic filler and a flame retardant auxiliary filler of 0.6 vol% or more and 2.5 vol% or less with respect to the total of the epoxy resin and the curing agent. The heat conductive insulating layer 11) cured in an integrated state with the metal plate 12) enables various electronic components and substrates (including heat dissipation substrates) excellent in heat conductivity, flame retardancy, and impact resistance. Subjected to.

  A thermally conductive material 17 in which a cured epoxy resin cured by reacting an epoxy resin with the curing agent has crystallinity (or heat conduction obtained by curing the heat transfer material 17 in an integrated state with the metal plate 12). The insulating layer 11) provides various electronic components and substrates (including a heat dissipation substrate) excellent in thermal conductivity, flame retardancy, and impact resistance.

  In addition, the flame retardancy is enhanced by using brominated epoxy (or brominated epoxy resin) as the flame retardant epoxy resin.

The curing agent, that is assumed to have a bivalent OH groups and / or NH ₂ groups, can stabilize the reactivity of the epoxy resin, further enhancing the matching property between the inorganic filler.

  Further, by assuming that the thermoplastic resin is an acrylic resin, the impact resistance is improved, and the wiring pattern 10 made of the heat conductive insulating layer 11, the metal plate 12, the lead frame, etc. in the case of producing a heat dissipation board. Since the stress concentration at the interface with the heat conductive insulating layer 11 can be reduced, not only the impact resistance of the material of the heat conductive insulating layer 11 is improved, but also the shock resistance at the interface (or stress concentration at the interface due to the impact). Suppress.

  Moreover, the impact resistance of the material itself is enhanced by using a core-shell type acrylic resin as the thermoplastic resin. A heat conductive insulating layer 11 produced using the heat conductive insulating layer 11 (further, in the heat dissipation board using the heat conductive insulating layer 11, the heat conductive insulating layer 11 and the wiring pattern 10 made of a metal plate 12, a lead frame, etc. Since the stress concentration at the interface portion can be reduced, not only the impact resistance of the material of the heat conductive insulating layer 11 itself is improved, but also the impact resistance at the interface portion (or stress concentration at the interface portion due to the impact) is suppressed. .

  The inorganic filler is an inorganic filler composed of at least one selected from alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, magnesium oxide, and zinc oxide, thereby achieving both high thermal conductivity and flame retardancy. it can. This is because these inorganic fillers have high thermal conductivity and flame retardancy.

  Further, the flame retardant aid filler is antimony trioxide to further enhance the flame retardancy.

  Further, an epoxy resin containing 40 vol% or more of a crystalline epoxy resin, a curing agent, a flame retardant epoxy resin of 3 vol% or more and 12 vol% or less with respect to the epoxy resin and the curing agent, the epoxy resin and the curing agent. 0.3 vol% or more and 2.5 vol% or less thermoplastic resin with respect to the total, and the epoxy resin, the curing agent, and the flame-retardant epoxy with an inorganic filler of 70 vol% or more and 88 vol% or less, A thermally conductive insulating layer comprising a flame retardant auxiliary filler of 0.6 vol% or more and 2.5 vol% or less with respect to the total of the epoxy resin and the curing agent, and a metal plate bonded to the thermally conductive insulating layer And a heat dissipating board comprising at least a part of the wiring pattern embedded in the heat conductive insulating layer, thereby providing a heat release having heat conductivity, flame resistance and impact resistance. To realize the board.

  Further, at least an epoxy resin containing 40 vol% or more of a crystalline epoxy resin preformed in a sheet form on the metal plate 12, a curing agent, and 3 vol% or more and 12 vol% or less with respect to the epoxy resin and the curing agent. A flame retardant epoxy resin, a thermoplastic resin of 0.3 vol% or more and 2.5 vol% or less based on the total of the epoxy resin and the curing agent, the epoxy resin, the curing agent, and the flame retardant epoxy The heat conductive material 17 which consists of 70 vol% or more and 88 vol% or less inorganic filler with respect to the sum total, and 0.6 vol% or more and 2.5 vol% or less flame retardant adjuvant filler with respect to the said epoxy resin and the said hardening | curing agent. And a step of setting the wiring pattern 10; a step of integrating the thermally conductive material 17 and the wiring pattern 10 on the metal plate 12; By the method of manufacturing heat dissipation board including a thermally conductive, to produce a heat radiation substrate with flame retardancy, impact resistance.

As described above, by using the thermally conductive cured product according to the present invention and the heat dissipation substrate using the heat conductive substrate and the method for manufacturing the heat dissipation substrate, the power supply circuit of the PDP television (PDP is a plasma display panel) and the light-emitting diode of the liquid crystal television It is possible to reduce the size and cost of a device that requires heat dissipation such as a backlight.

Cutaway view of heat dissipation board in the embodiment (A) (B) is sectional drawing explaining the heat dissipation mechanism of the heat dissipation board | substrate which embedded both the wiring patterns. Sectional drawing explaining pre-formation (sheet form) of heat conductive insulating material (A) (B) is sectional drawing explaining an example of the manufacturing method of a heat sink. Sectional view of a conventional heat dissipation board Schematic diagram of changes during polymerization of monomers with mesogenic groups

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Wiring pattern 11 Thermal conductive insulating layer 12 Metal plate 13 Electronic component 14 Arrow 15 Film 16 Molding apparatus 17 Thermal conductive material 18 Press

Claims (5)

An epoxy resin containing 40 vol% or more of a crystalline epoxy resin having the following structural formula ;
A curing agent;
3 to 12 vol% brominated epoxy resin with respect to the total of the epoxy resin and the curing agent,
A core-shell type acrylic resin of 0.3 vol% to 2.5 vol% with respect to the total of the epoxy resin and the curing agent;
70 vol% with respect to the total of the epoxy resin, the curing agent and the brominated epoxy resin
An inorganic filler composed of at least one selected from alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, magnesium oxide, and zinc oxide in an amount of 88 vol% or less;
From at least one selected from a hydroxyl compound, a boron compound, an antimony compound, a molybdenum compound, and a metal oxide salt of 0.6 vol% or more and 2.5 vol% or less with respect to the total of the epoxy resin and the curing agent With the flame retardant aid filler,
A thermally conductive cured product comprising a cured product of a thermally conductive material having :
The cured epoxy resin obtained by reacting the epoxy resin and the curing agent has crystallinity,
After 10 seconds of flame contact, flame is extinguished and the combustion time (t1) until extinguishing is measured. After flame extinguishing, after 10 sec. Flame contact, flame is extinguished and the combustion time until extinguishing (t2) is measured, t1 and t2 are Both are less than 10 seconds,
A thermally conductive cured product characterized in that it does not crack or crack even when it is naturally dropped onto a concrete from a height of 1.5 m.

The thermally conductive cured product according to claim 1, wherein the curing agent has a divalent OH group and / or an NH ₂ group. The heat conductive cured product according to claim 1, wherein the flame retardant auxiliary filler is antimony trioxide. An epoxy resin containing 40 vol% or more of a crystalline epoxy resin having the following structural formula ;
A curing agent;
3 to 12 vol% brominated epoxy resin with respect to the total of the epoxy resin and the curing agent,
A core-shell type acrylic resin of 0.3 vol% to 2.5 vol% with respect to the total of the epoxy resin and the curing agent;
70 vol% with respect to the total of the epoxy resin, the curing agent and the brominated epoxy resin
An inorganic filler composed of at least one selected from alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, magnesium oxide, and zinc oxide in an amount of 88 vol% or less;
From at least one selected from a hydroxyl compound, a boron compound, an antimony compound, a molybdenum compound, and a metal oxide salt of 0.6 vol% or more and 2.5 vol% or less with respect to the total of the epoxy resin and the curing agent A thermally conductive solid layer made of a cured product of a thermally conductive material having a flame retardant aid filler, a metal plate bonded to the thermally conductive solid layer,
A heat dissipating board having a wiring pattern in which at least a part of the heat conducting solid layer is embedded ,
The cured epoxy resin obtained by reacting the epoxy resin and the curing agent has crystallinity,
After 10 seconds of flame contact, flame is extinguished and the combustion time (t1) until extinction is measured. After flame extinguishing, after 10 sec. Both are less than 10 seconds,
A heat dissipation board characterized by that it does not crack or crack even if it falls naturally on concrete from a height of 1.5 m.

At least with respect to the total of the epoxy resin containing 40 vol% or more of the crystalline epoxy resin having the following structural formula preformed into a sheet shape on a metal plate, a curing agent, and the epoxy resin and the curing agent 3 vol% or more and 12 vol% or less brominated epoxy resin, 0.3 vol% or more and 2.5 vol% or less core-shell type acrylic resin with respect to the total of the epoxy resin and the curing agent, the epoxy resin and the curing Inorganic composed of at least one selected from alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, magnesium oxide, and zinc oxide in an amount of 70 vol% to 88 vol% with respect to the total of the agent and the brominated epoxy resin 0.6 vol% or more and 2.5 vol% or less with respect to the total of the filler, the epoxy resin, and the curing agent Hydroxide compounds, boron compounds, antimony compounds, molybdenum compounds, and the thermally conductive material having a flame-retardant auxiliary filler consisting of at least one kind, the selected metal oxide salt,
A step of setting a wiring pattern;
Integrating the thermally conductive material and the wiring pattern on the metal plate;
A method of manufacturing a heat dissipation board including :
The cured epoxy resin obtained by reacting the epoxy resin and the curing agent has crystallinity,
After 10 seconds of flame contact, flame is extinguished and the combustion time (t1) until extinction is measured. After flame extinguishing, after 10 sec. Both are less than 10 seconds,
A method for producing a heat dissipation board, characterized in that cracks and cracks do not occur even when the glass is naturally dropped onto concrete from a height of 1.5 m.

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