Cover for heat-generating electronic components

Abstract

This cover for a heat generating electronic component is formed of a hollow structure having one or more openings through which an electronic circuit component is inserted. The cover for a heat generating electronic component is characterized in that an inner wall surface of the hollow structure has one or more protrusion portions. Accordingly, provided is a cover which is for a heat generating electronic component and which enables suppression of detachment of an electronic component.

Description

Technical Field

[0001] The present invention relates to a cover for a heat-generating electronic component.

Background Art

[0002] In recent years, with the miniaturization and high density of various electronic devices, the heat dissipation problem of heat-generating electronic components such as power transistors incorporated in these electronic devices has been spotlighted.

[0003] A typical power transistor T has a configuration as shown in FIG. 4. The transistor in FIG. 4 has a transistor body 11 and a terminal 12 protruding from one end surface of the transistor body 11. Further, it includes a flat heat sink 13 attached so as to be in the same plane as the bottom surface 11a of the power transistor body 11. One end side of this heat sink is inserted into a notch 11b formed by cutting out the transistor body 11, and the other end side is installed in a direction opposite to the protruding direction of the terminal 12. Also, one of the plurality of terminals 12 is connected inside the flat heat sink 13 and the power transistor body 11. The heat generated in the power transistor is thermally conducted to the outside through a heat-conductive material sandwiched between this heat sink 13 and an external heat sink such as a metal chassis.

[0004] These heat-conductive materials include liquid materials such as heat-dissipating grease and molded products such as heat-dissipating sheets from the viewpoints of heat dissipation and insulation and assemblability. On the other hand, when arranging the heat-dissipating material in a planar shape, the creepage distance for electrical insulation (distance from other electronic components and external heat sinks) becomes large. Therefore, a method has been devised in which a heat-conductive composition is molded into a tubular cover or a hollow cover having an opening on one side to three-dimensionally enclose electronic components (Patent Document 1, Patent Document 2). The tubular cover is used as shown in FIG. 5. A transistor is inserted into one end of the tubular cover 14, sandwiched between two external heat sinks 15 and 16, and fixed by a fixing screw 17. Similarly, the hollow cover 18 having an opening on one side has a shape with an opening 19 as shown in FIG. 6, and the transistor T is inserted through the opening 19 for use. In addition, in order to more effectively achieve both heat dissipation and electrical insulation, a structure in which the thickness of each surface of the hollow cover is changed has also been proposed (Patent Document 3). That is, a thick surface is grounded on the heat sink side where current leakage is likely to occur, and the thickness of the opposite surface is made thin to enhance heat dissipation.

[0005] The inner dimensions of these heat-conductive molded products are designed according to the cross-sectional dimensions of the power transistor, and there is an advantage that they can be easily mounted on the transistor. However, because they can be easily attached, until they are fixed to an external heat sink such as a heat sink, they may easily fall off or be misaligned due to vibrations during transportation in the manufacturing process or processing operations, which has a problem of deteriorating work efficiency and product yield.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a cover for a heat-generating electronic component capable of suppressing the dropout of electronic components such as transistors.

Means for Solving the Problems

[0008] In order to solve the above problems, the present invention provides a cover for a heat-generating electronic component comprising a hollow structure having one or more openings for inserting an electronic circuit component, wherein the inner wall surface of the hollow structure has one or more convex shapes.

[0009] With such a cover for a heat-generating electronic component of the present invention, dropout of electronic components such as transistors can be suppressed.

[0010] In this case, it is preferable that the height of the convex shape is in the range of 0.1 to 1 mm.

[0011] If the height of the convex shape is within this range, dropout and displacement during substrate manufacturing can be sufficiently suppressed, and insertion of transistors and the like can be performed smoothly.

[0012] Further, it is preferable that the cover for a heat-generating electronic component of the present invention is made of a cured product of a silicone rubber composition containing silicone rubber and a heat-conductive filler.

[0013] If it is such a thing, since the material which forms a cover has heat conductivity and electrical insulation, and is a soft elastic material, it does not damage at the time of inserting an electronic component, insertion is easy, and it has sufficient heat resistance that it can be used even when exposed to high temperature by the heat generated in the electronic component.

[0014] In this case, it is preferable that the cured product of the silicone rubber composition has a thermal conductivity of 0.5 W / m·K or more.

[0015] If it is such a thing, it is possible to sufficiently promote the heat dissipation of heat-generating electronic components such as power transistors.

[0016] Further, it is preferable that the dielectric breakdown voltage in air at a thickness of 0.45 mm of the cured product of the silicone rubber composition is 4.5 kV or more.

[0017] If it is such a thing, since it has good electrical insulation properties, it is possible to more effectively achieve both heat dissipation and electrical insulation.

[0018] Further, the silicone rubber composition is the following (A) to (D) (A) Organopolysiloxane having an average degree of polymerization of 3,000 to 10,000: 100 parts by mass, (B) Organopolysiloxane having an average degree of polymerization of 2 to 2,000 and having alkenyl groups only at both ends of the molecular chain: 10 to 100 parts by mass, (C) Thermally conductive filler: 500 to 2,700 parts by mass, and (D) Curing agent: effective amount It is preferably a thermally conductive silicone rubber composition containing the above.

[0019] Such a thermally conductive silicone rubber composition is more preferably a silicone rubber composition containing a thermally conductive filler that serves as a matrix for the cover for heat-generating electronic components of the present invention.

[0020] In this case, in the silicone rubber composition, it is preferable that the total content of the diorganocyclopolysiloxane having 3 to 10 silicon atoms contained in the component (A) is 500 ppm or less with respect to the total amount of the component (A).

[0021] Such a thermally conductive silicone rubber composition is even more preferably a silicone rubber composition that serves as a matrix for the cover for heat-generating electronic components of the present invention.

Effects of the Invention

[0022] As described above, according to the present invention, it is possible to provide a cover for a heat-generating electronic component that can suppress the detachment of electronic components such as transistors.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0024] As a result of intensive studies to achieve the above object, the inventors have found that by having one or more convex shapes on the inner wall surface of a hollow structure having one or more openings, it is possible to easily attach to a transistor and suppress the detachment and displacement from the transistor, and thus have arrived at the present invention.

[0025] That is, the present invention is a cover for a heat-generating electronic component comprising a hollow structure having one or more openings for inserting an electronic circuit component, characterized in that the inner wall surface of the hollow structure has one or more convex shapes.

[0026] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0027] The cover for heat-generating electronic components of the present invention is a hollow structure having at least one opening for inserting an electronic circuit component, and is characterized in that it has at least one convex portion on the inner wall surface of the hollow structure. The heat-generating electronic component is not particularly limited as long as it is an electronic component that generates heat during use, such as a power transistor. Hereinafter, a power transistor will be taken as an example of the heat-generating electronic component for explanation.

[0028] The cover for heat-generating electronic components according to an embodiment of the present invention is shown in FIG. 1. This cover is preferably used as a power transistor cover as shown in FIG. 4 above, and has an opening 2 for inserting the power transistor T at one end of the cover 1. Further, the heat-generating electronic component cover of the present invention is provided with a convex shape 3 on the inner wall for preventing the transistor T from falling off after the transistor T is inserted.

[0029] Here, if the opening 2 has a shape approximated to the cross section of the transistor T, the convex shape 3 will contact the transistor after insertion, and the pressure applied to the transistor can suppress the cover 1 from falling off.

[0030] The width of the opening of the cover for heat-generating electronic components may be such that the power transistor can be inserted. Usually, it is substantially the same width and height as the maximum width and maximum height of the power transistor, or is usually 0.1 to 3 mm, preferably 0.3 to 2 mm, particularly preferably about 0.5 to 1 mm larger than the above maximum width and maximum height. By forming the width and height of the opening (and the hollow portion including the opening) slightly larger than the maximum width and maximum height of the power transistor in this way, even if the power transistor with the cover of the present invention is arranged in the electronic device, there will be no surplus space around the transistor. Also, the depth (length) of the cover for heat-generating electronic components is preferably such that at least 1 / 2, more preferably at least 4 / 5 of the terminals protrude from the opening 2 when mounted on the power transistor.

[0031] The thickness of the cover for the heat-generating electronic component of the present invention is preferably 0.1 to 2.0 mm, more preferably 0.1 to 1.0 mm. If it is 0.1 mm or more, the withstand voltage strength becomes sufficiently high. For example, when using a metal chassis or metal heat dissipation fins as an external heat dissipation plate, there is no short circuit with these, and furthermore, the self-supporting force is sufficient and the shape is maintained. On the other hand, if the thickness of the plate portion (cover) is 2.0 mm or less, it is excellent in terms of heat dissipation effect.

[0032] The convex shape on the inner wall surface of the cover for the heat-generating electronic component of the present invention is characterized by having one or more, preferably 1 to 10, more preferably 1 to 5. If the convex shape is 10 or less, the space between the power transistor is sufficiently small and does not hinder heat conduction.

[0033] The shape forming the convex portion of the convex shape of the present invention is not particularly limited. Specifically, columnar shapes such as quadrangular prism, triangular prism, and circular column, and frustum shapes such as quadrangular pyramid, triangular pyramid, and circular cone can be mentioned.

[0034] The height of the convex shape on the inner wall surface of the cover for the heat-generating electronic component of the present invention is preferably in the range of 0.1 to 1 mm, more preferably 0.2 to 0.5 mm. If the height of the convex shape is 0.1 mm or more, the dropping and displacement during substrate manufacturing can be sufficiently suppressed, and if it is 1 mm or less, it does not interfere during the insertion of the transistor.

[0035] Each dimension of the inner wall surface of the cover for the heat-generating electronic component of the present invention is preferably increased within the range of 0 to 1.0 mm with respect to the dimension of the electronic component to be covered, and more preferably 0.1 to 0.8 mm. If the dimension of the inner wall surface of the cover for the heat-generating electronic component, which is increased with respect to the dimension of the electronic component, is 1.0 mm or less, the effect of suppressing dropping due to the convex shape can be effectively obtained, and when it is equal to or larger than the dimension of the electronic component, preferably larger than the dimension, the insertion of the electronic component becomes easy.

[0036] The material for forming the cover for the heat-generating electronic component may be any material having thermal conductivity and electrical insulation. Further, considering the damage during insertion of the electronic component and the ease of insertion, a soft elastic material such as rubber is preferable. Also, since there is a possibility of being exposed to high temperatures due to the heat generated by the electronic component, it is preferable to use a silicone rubber composition containing a thermal conductivity filler in the silicone rubber.

[0037] The silicone rubber composition containing a thermal conductivity filler that serves as the matrix of the cover for the heat-generating electronic component of the present invention comprises the following components (A) to (D): (A) Organopolysiloxane having an average degree of polymerization of 3,000 to 10,000: 100 parts by mass, (B) Organopolysiloxane having an average degree of polymerization of 2 to 2,000 and having alkenyl groups only at both ends of the molecular chain: 10 to 100 parts by mass, (C) Thermal conductivity filler: 500 to 2,700 parts by mass, and (D) Curing agent: effective amount It is more preferable that the composition is a thermally conductive silicone rubber composition containing further components as required.

[0038] [(A) Organopolysiloxane having an average degree of polymerization of 3,000 to 10,000] Component (A) serves as the main component of the silicone rubber composition, and those having an average composition formula represented by the following formula (1) are preferable. R a SiO (4-a) / 2 (1)

[0039] In the above formula (1), R is independently a monovalent hydrocarbon group having 1 to 8 carbon atoms. For example, alkyl groups such as methyl group, ethyl group, and propyl group, alkenyl groups such as vinyl group and allyl group, aryl groups such as phenyl group and tolyl group, cycloalkyl groups such as cyclohexyl group and cyclopentyl group, etc. may be mentioned. Further, a part or all of the hydrogen atoms directly bonded to the carbon atoms of these groups may be substituted with halogen atoms such as chlorine and fluorine. Preferably, they are methyl group, phenyl group, trifluoropropyl group, and vinyl group. Also, a is a positive number of 1.85 to 2.10.

[0040] The organopolysiloxane preferably has a linear molecular structure, but may have a partially branched structure in the molecule. Further, the organopolysiloxane preferably has its molecular chain ends blocked with triorganosilyl groups or hydroxyl groups. Examples of the triorganosilyl group include trimethylsilyl group, dimethylvinylsilyl group, trivinylsilyl group, methylphenylvinylsilyl group, methyldiphenylsilyl group, dimethylphenylsilyl group, dimethylhydroxysilyl group, etc.

[0041] The average degree of polymerization of the component (A) is 3,000 to 10,000, preferably 5,000 to 10,000.

[0042] In addition, the average degree of polymerization mentioned in this specification refers to the average degree of polymerization determined from the number average molecular weight using polystyrene as a standard substance and tetrahydrofuran (THF) as a solvent by gel permeation chromatography (GPC).

[0043] The total content of the diorganocyclopolysiloxane having 3 to 10 silicon atoms contained in the component (A) is preferably 500 ppm (mass basis) or less with respect to the total amount of the component (A). The lower limit is preferably as low as possible and is not particularly limited, but may be, for example, 10 ppm or more.

[0044] [(B) Alkenyl group-containing organopolysiloxane having an average degree of polymerization of 2 to 2,000] (B) component is a component that is subjected to a crosslinking reaction in the silicone rubber composition. It is an organopolysiloxane having an average degree of polymerization of 2 to 2,000 and alkenyl groups only at both ends of the molecular chain. As the alkenyl group, an alkenyl group having 2 to 8 carbon atoms is preferable, and examples thereof include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, a hexenyl group, and a cyclohexenyl group. Among them, lower alkenyl groups having 2 to 4 carbon atoms such as a vinyl group and an allyl group are preferable, and a vinyl group is particularly preferable. This organopolysiloxane of component (B) may be used alone or in combination of two or more having different average degrees of polymerization.

[0045] The average degree of polymerization of the component (B) is 2 to 2,000, preferably 10 to 2,000.

[0046] The blending amount of the component (B) is preferably 10 to 100 parts by mass, more preferably 30 to 70 parts by mass, based on 100 parts by mass of the component (A).

[0047] [(C) Thermal Conductive Filler] (C) component is a component used as a filler for imparting thermal conductivity in the silicone rubber composition. The component (C) may be any material having thermal conductivity, and it is preferably further provided with electrical insulation. Although not particularly limited, for example, metal oxides such as alumina, silica, magnesia, red iron oxide, beryllia, titania, and zirconia, metal nitrides such as aluminum nitride, silicon nitride, and boron nitride, metal hydroxides such as magnesium hydroxide, and substances generally used as thermal conductive fillers such as artificial diamond or silicon carbide can be used. The shape of the thermal conductive filler is not particularly limited, and it can be made into a crushed shape, a spherical shape, etc. as required. The average particle diameter (volume average particle diameter) of the thermal conductive filler is a measured value by the laser diffraction / scattering method (Microtrac method), and is preferably 0.1 to 100 μm, more preferably 0.5 to 50 μm, and even more preferably 1 to 45 μm.

[0048] The blending amount of the component (C) is preferably 500 to 2,700 parts by mass, more preferably 600 to 2,500 parts by mass, based on 100 parts by mass of the component (A).

[0049] These thermal conductive fillers may be surface-treated with a surface treatment agent (wetter) such as a silane coupling agent or its partial hydrolyzate, an alkylalkoxysilane or its partial hydrolyzate, organosilazanes, organopolysiloxane oil, a hydrolyzable functional group-containing organopolysiloxane, etc. Examples of the surface treatment agent include polysiloxanes having an alkoxy group or a hydroxy group in the molecule, such as a dimethylpolysiloxane blocked with a trialkoxysilyl group at one end. The linkage state of the siloxane units in the polysiloxane may be block or random. These treatments may be performed by pretreating the thermal conductive filler itself, or by performing the treatment at the time of mixing the organopolysiloxane of the component (A) or (B) with the (C) thermal conductive filler.

[0050] [(D) Curing agent] (D) component is a component for curing the silicone rubber composition. The curing agent is appropriately selected according to the mechanism of the crosslinking reaction of the composition.

[0051] When the crosslinking is a radical reaction, an organic peroxide is used. Specifically, benzoyl peroxide, monochlorobenzoyl peroxide, bis(2,4-dichlorobenzoyl) peroxide, o-methylbenzoyl peroxide, p-methylbenzoyl peroxide, di(t-butyl) perbenzoate, dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, di(t-butyl) peroxide, etc. are exemplified. The organic peroxide is preferably added in an amount of 0.1 to 10 parts by mass, particularly 0.2 to 5 parts by mass, based on 100 parts by mass of the total amount of the organopolysiloxanes of the components (A) and (B).

[0052] In the case where the crosslinking is an addition reaction, an organohydrogensiloxane containing two or more hydrogen atoms directly bonded to silicon atoms in one molecule and an effective amount (catalytic amount) of a platinum group element (preferably platinum) or a compound thereof are used as a catalyst. In this case, it is necessary that the organopolysiloxane contains two or more alkenyl groups in one molecule. The organohydrogenpolysiloxane is preferably blended in an amount such that the hydrogen atoms directly bonded to silicon atoms are 0.5 to 5 times, particularly 0.6 to 3 times, the alkenyl groups contained in the component (A) and the component (B).

[0053] When the crosslinking is a condensation reaction, a hydrolyzable silane or siloxane containing two or more, preferably three or more, hydrolyzable groups such as alkoxy groups, acetoxy groups, and oxime groups in one molecule is used as a crosslinking agent (curing agent). The blending amount is 1 to 20 parts by mass, particularly 2 to 10 parts by mass, based on 100 parts by mass of the total amount of the organopolysiloxanes of the component (A) and the component (B). Also, it is preferable to use an organometallic compound such as Sn, Ti, Fe, or Co as a catalyst. In this case, it is necessary that both ends of the molecular chain of the organopolysiloxane are blocked with hydroxyl groups or alkoxy groups.

[0054] The blending amount of the curing agent (crosslinking agent) may be an effective amount and can be appropriately adjusted according to the types and blending ratios of other components. Other examples include radical reactions using ultraviolet irradiation or electron beam irradiation, but the curing method is not limited thereto.

[0055] [Other Components] If necessary, the silicone rubber composition of the present invention may be blended with the above-described surface treatment agent and further other components. For example, heat resistance improvers such as iron oxide and cerium oxide; viscosity adjusters such as silica; colorants; optional components such as internal release agents such as methylphenylpolysiloxane can be blended.

[0056] [Production of Silicone Rubber Composition] The above silicone rubber composition can be produced by mixing the above components. The production method may adopt a known method and is not particularly limited. For example, the silicone rubber composition can be produced as follows. (1) Charge the above components (A) to (C), and the surface treatment agent and the internal release agent which are optional components, into a 5 L kneader for heat treatment, and mix them at 25 to 40 °C for 30 minutes. Then, heat the inside of the kneader, and after confirming that the temperature of the composition has reached 170 °C, perform heating and stirring for another 2 hours. (2) After heating and stirring, cool to near room temperature (25 °C), and take out the kneaded compound. Further, using two rolls, add a curing agent to the compound and knead it to obtain a thermally conductive silicone rubber composition.

[0057] [Molding method (method for manufacturing a cover for a heat-generating electronic component)] For molding the cover for a heat-generating electronic component of the present invention, mold molding in which the above silicone rubber composition is injected into a molding die and heat-cured is preferable. In particular, transfer molding in which a heat-softened raw material is injected into a mold and cured is preferable from the viewpoints of dimensional accuracy and mass productivity of the molded product. When performing molding by transfer molding, the pressure for pressing the silicone rubber composition into the mold is preferably 100 to 300 kgf / cm 2 . If the pressing pressure is 300 kgf / cm 2 or less, the oil-like component of the silicone rubber composition and the thermally conductive filler will not separate. If it is 100 kgf / cm 2 or more, the pressing will not take a long time and the curing of the raw material will not proceed. Also, in order to demold the molded cover for a heat-generating electronic component from the mold, it is effective to apply and spray a surfactant on the mold surface.

[0058] [Cured product of the silicone rubber composition] The cover for a heat-generating electronic component of the present invention preferably consists of a cured product of a silicone rubber composition containing a silicone rubber and a thermally conductive filler. For such a material, since the material forming the cover has thermal conductivity and electrical insulation and is a soft elastic material, it does not cause damage during the insertion of electronic components and is easy to insert. Also, it has sufficient heat resistance to be used even when exposed to high temperatures due to the heat generated by the electronic components.

[0059] It is preferable that the cured product of the silicone rubber composition has a thermal conductivity of 0.5 W / m·K or more. For such a material, the heat dissipation of heat-generating electronic components such as power transistors can be sufficiently promoted. The upper limit is preferably as high as possible and is not particularly limited, but for example, it may be 10 W / m·K or less.

[0060] In the present invention, the thermal conductivity may be measured, for example, by using TPA-501 (manufactured by Kyoto Electronics Industry Co., Ltd.) and measuring the thermal conductivity at 25°C by the hot disk method in accordance with ISO22007-2.

[0061] Also, it is preferable that the breakdown voltage in air at a thickness of 0.45 mm of the cured product of the above silicone rubber composition is 4.5 kV or more. For such a material, since it has good electrical insulation, heat dissipation and electrical insulation can be achieved more effectively. The upper limit is preferably as high as possible and is not particularly limited, but for example, it may be 10 kV or less.

[0062] For the measurement of the breakdown voltage in air at a thickness of 0.45 mm of the cured product (molded product), the measurement object may be attached to the electrode, a voltage of 4.5 kV may be applied in air for 10 seconds, and the presence or absence of a leakage current may be measured.

Examples

[0063] Hereinafter, examples and comparative examples will be shown to specifically explain the present invention, but the present invention is not limited to the following examples.

[0064] [Preparation of thermally conductive silicone composition] (1) The components (A) to (C) shown below, and the optional components (E) and (F) were charged into a 5 L kneader for heat treatment (manufactured by Inoue Seisakusho), and mixed at 25 to 40 °C for 30 minutes. Thereafter, after heating the inside of the kneader and confirming that the temperature of the composition reached 170 °C, heating and stirring were further carried out for 2 hours.

[0065] Component (A) Dimethylpolysiloxane having vinyl groups at both ends and an average degree of polymerization of 8,000: 100 parts by mass

Chemical formula

[0066] Component (B) (B-1) Dimethylpolysiloxane having vinyl groups at both ends and an average degree of polymerization of 500: 27 parts by mass

Chemical formula

[0067] (B-2) Dimethylpolysiloxane having vinyl groups at both ends and an average degree of polymerization of 1,600: 15 parts by mass

Chemical formula

[0068] Component (C) Thermal conductivity filler: (C-1) Average particle size: 1 μm: Crushed alumina 1080 parts by mass (C-2) Average particle size: 1 μm: Spherical alumina 385 parts by mass (C-3) Average particle size: 10 μm: Spherical alumina 462 parts by mass (C-4) Average particle size: 45 μm: Spherical alumina 231 parts by mass (The average particle size is the volume average particle size measured by the laser diffraction / scattering method.)

[0069] Component (E) As the surface treatment agent (wetting agent component) of the component (C), 19 parts by mass of a mono-terminal trialkoxysilyl group-blocked dimethylpolysiloxane represented by the following formula (E-1): [Chemical formula] and 6 parts by mass of a vinyl-containing dimethylpolysiloxane represented by the following formula (E-2): [Chemical formula] (The linking state of the above siloxane units may be block or random.)

[0070] (Component (F)) As an internal release agent, 7 parts by mass of a methylphenylpolysiloxane represented by the following formula: [Chemical formula] (The linking state of the above siloxane units may be block or random.)

[0071] (2) After heating and stirring, it was cooled to near room temperature (25 °C), and the kneaded compound was taken out. Further, using a two-roll (Daisin Machine Co., Ltd.), the following component (D) was kneaded into the compound as a curing agent to obtain a thermally conductive silicone rubber composition.

[0072] (D) An organic peroxide represented by the following formula: 0.8 parts by mass [Chemical formula]

[0073] [Thermal conductivity measurement] The obtained thermally conductive silicone rubber composition was poured into a flat mold with a depth of 6 mm, and using a high-pressure press machine (manufactured by Shoji Iron Works Co., Ltd.), it was press-cured at 165 °C and 100 kgf / cm 2 for 10 minutes to produce a 6 mm-thick sheet. Two 6-mm-thick sheets were used, and the thermal conductivity at 25°C was measured by the hot disk method conforming to ISO22007-2 using TPA-501 (manufactured by Kyoto Electronics Industry Co., Ltd.). As a result, the thermal conductivity was 2.8 W / m·K.

[0074] [Molding of Covers for Exothermic Electronic Components] The heat-conductive silicone rubber composition after kneading was molded by heating and pressing at 165°C and 100 kgf / cm² for 10 minutes using a transfer molding machine (manufactured by PRC Co., Ltd.) consisting of a piston, a pot, a medium mold, and a lower mold. After demolding the molded product, secondary vulcanization was performed at 150°C for 1 hour to produce a cover for exothermic electronic components. The shape of the cover for exothermic electronic components is as shown in Examples 1 and Comparative Example 1 below. 2 After demolding the molded product, secondary vulcanization was performed at 150°C for 1 hour to produce a cover for exothermic electronic components. The shape of the cover for exothermic electronic components is as shown in Examples 1 and Comparative Example 1 below.

[0075] [Example 1] The heat-conductive silicone rubber composition was molded as described above to form a cover for exothermic electronic components into the shape shown in Fig. 2 (with a convex-shaped part). Dimensions (unit: mm) are shown in the figure.

[0076] [Comparative Example 1] The heat-conductive silicone rubber composition was molded as described above to form a cover for exothermic electronic components into the shape shown in Fig. 3 (without a convex-shaped part). Dimensions (unit: mm) are shown in the figure.

[0077] [Measurement of Dielectric Breakdown of Molded Products] The covers for exothermic electronic components prepared in Example 1 and Comparative Example 1 were attached to electrodes (manufactured by Safe Co., Ltd.) with dimensions of 15 mm × 4.5 mm × height 20 mm, a voltage of 4.5 kV was applied for 10 seconds, and the presence or absence of leakage current was measured. The results are shown in Table 1.

[0078] [Drop Test] The molded products prepared in the shapes of Example 1 and Comparative Example 1 were attached to a TO-247 type transistor (Fig. 4, CLA 50 E 1200 HB manufactured by IXYS Corporation) with the terminal part facing upward and fixed to a vibration pedestal, and vibration with an amplitude of 10 cm and a frequency of 10 Hz in the gravitational direction was applied for 5 minutes to confirm the presence or absence of dropping from the transistor. The results are shown in Table 1.

[0079]

Table 1

[0080] As is clear from the results in Table 1, the provision of the convex shape can suppress the cover for the heat-generating electronic component from falling off the transistor.

[0081] Note that the present invention is not limited to the above-described embodiment. The above-described embodiment is an example, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same operational effects is included in the technical scope of the present invention.

Claims

1. A cover for a heat-generating electronic component made of a hollow structure having one or more openings for inserting an electronic circuit component, wherein the inner wall surface of the hollow structure has one or more convex shapes, and The cover for a heat-generating electronic component is characterized in that it is made of a cured product of a silicone rubber composition containing silicone rubber and a heat-conductive filler.

2. The cover for a heat-generating electronic component according to claim 1, wherein the height of the convex shape is in the range of 0.1 to 1 mm.

3. The cover for a heat-generating electronic component according to claim 1, wherein the cured product of the silicone rubber composition has a thermal conductivity of 0.5 W / m·K or more.

4. The cover for a heat-generating electronic component according to claim 2, wherein the cured product of the silicone rubber composition has a thermal conductivity of 0.5 W / m·K or more.

5. The cover for a heat-generating electronic component according to claim 1, wherein the breakdown voltage in air at a thickness of 0.45 mm of the cured product of the silicone rubber composition is 4.5 kV or more.

6. The cover for a heat-generating electronic component according to claim 2, wherein the breakdown voltage in air at a thickness of 0.45 mm of the cured product of the silicone rubber composition is 4.5 kV or more.

7. The cover for a heat-generating electronic component according to claim 3, wherein the breakdown voltage in air at a thickness of 0.45 mm of the cured product of the silicone rubber composition is 4.5 kV or more.

8. The cover for a heat-generating electronic component according to claim 4, wherein the breakdown voltage in air at a thickness of 0.45 mm of the cured product of the silicone rubber composition is 4.5 kV or more.

9. The silicone rubber composition is the following (A) to (D) (A) Organopolysiloxane having an average degree of polymerization of 3,000 to 10,000: 100 parts by mass, (B) Organopolysiloxane having an average degree of polymerization of 2 to 2,000 and having alkenyl groups only at both ends of the molecular chain: 10 to 100 parts by mass, (C) Heat-conductive filler: 500 to 2,700 parts by mass, and (D) Curing agent: effective amount The cover for a heat-generating electronic component according to any one of claims 1 to 8, which is a heat-conductive silicone rubber composition containing the above components.

10. In the silicone rubber composition, the total content of the diorganocyclopolysiloxane having 3 to 10 silicon atoms contained in the component (A) is 500 ppm or less with respect to the total amount of the component (A), and the cover for a heat-generating electronic component according to claim 9 is characterized in that.

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