JP2015076356A - Heat radiation structure and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat radiation structure which achieves high heat radiation efficiency, strength, and toughness, enables weight reduction, and is preferably used as a lamp component on which LEDs etc. are mounted.SOLUTION: In a heat radiation structure, a resin heat radiation component having heat conductivity and heating sources 3 disposed on the resin heat radiation component through a layer having heat conductivity lower than the resin heat radiation component are disposed. In the heat radiation structure, the resin heat radiation component is formed by a thermoplastic resin containing a heat conductive filler. Further, a lower heat conductivity component has a snap fit part and/or a screw hole part.

Description

  The present invention relates to a heat dissipating structure for mounting a heat generating element or dissipating heat from the heat generating element.

LED elements used in lamp parts and CPUs mounted on computer motherboards are becoming smaller and higher in performance, and countermeasures for heat generation of LED elements and CPUs are becoming important. As a countermeasure against such heat generation, a heat sink has been used conventionally.
For example, many heat sinks for LED lamps (LED lighting) have been conventionally employed that are made of aluminum (including an aluminum alloy) and are made of aluminum die-casting or extrusion (for example, Patent Documents 1 and 2). ).
When a metal is used as the heat sink, there is a problem that the weight as a component increases due to an increase in size or an increase in the number of fins in order to improve heat dissipation efficiency.
In addition, when aluminum is used as the heat sink, it is necessary to anodize the surface of the aluminum in order to increase heat dissipation efficiency.

JP 2007-193960 A JP2013-197020A

As a technique for reducing the weight of the heat sink without impairing the heat dissipation efficiency of the heat sink, it has been studied to use a heat sink as a resin.
For example, by performing injection molding using a thermoplastic resin, it is possible to manufacture a heat sink with an increased shape flexibility. However, the inclusion of a conductive filler such as carbon in the thermoplastic resin simply to increase the heat dissipation efficiency can increase the heat dissipation efficiency but decreases the strength and toughness of the component.
On the other hand, when a reinforcing material such as glass fiber is used together with a conductive filler in order to ensure strength and toughness, it has been difficult to sufficiently increase the heat dissipation efficiency.

  This invention solves the said subject, and it aims at providing the thermal radiation structure which made the heat radiation efficiency, intensity | strength, and toughness compatible, and reduced in weight.

As a result of intensive studies to solve the above problems, the present inventors have arrived at the present invention.
That is, the gist of the present invention is as follows.
(1) A heat radiating structure in which a heat source is disposed on a resin heat radiating component having thermal conductivity and a layer having a lower thermal conductivity than the resin heat radiating component on the resin heat radiating component.
(2) The heat dissipation structure according to (1), wherein the resin heat dissipation component is made of a thermoplastic resin containing a heat conductive filler.
(3) The heat dissipation structure according to (1) or (2), wherein the low thermal conductivity component has a snap fit portion and / or a screw hole portion.
(4) The heat dissipating structure according to any one of (1) to (3), wherein the member constituting the snap fit portion and / or the screw hole portion is an electrically insulating thermoplastic resin.
(5) The heat dissipation structure according to (1) to (4), wherein the heat dissipation structure is an LED.
(6) After obtaining a low thermal conductivity part having a snap fit part and / or a threaded hole part by injection molding, a step of arranging the heat source and then integrating the resin heat radiation part and the heat source (1) )-(5) The manufacturing method of the thermal radiation structure.
(7) A lamp component using the heat dissipation structure of (1) to (5).

  According to the present invention, it is possible to provide a heat radiating structure that achieves both heat radiating efficiency, strength, and toughness and is lightened. Such a heat dissipation structure can be suitably used, for example, as a lamp component mounted with an LED or the like.

It is a perspective view regarding the conventional heat dissipation structure. It is a perspective view of the thermal radiation structure concerning an embodiment of the invention. It is a perspective view of the thermal radiation structure which combined the thermal radiation component which concerns on embodiment of this invention. It is a perspective view of the heat dissipation structure concerning an embodiment of the invention, and a case integrated product which stores it.

Hereinafter, the present invention will be described in detail.
In the heat dissipating structure of the present invention, a heat radiation source is disposed on a resin heat dissipating part having thermal conductivity and a layer having a lower thermal conductivity than the resin heat dissipating part on the resin heat dissipating part. A heat dissipating structure, wherein the resin heat dissipating part is made of a thermoplastic resin containing a heat conductive filler.

  The resin heat radiating component having thermal conductivity refers to a heat radiating component formed by molding a resin having thermal conductivity. The resin having thermal conductivity needs to be a thermoplastic resin containing a thermal conductive filler.

  The thermoplastic resin that can be used in the present invention is not particularly limited, but ethylene-α-olefin copolymers such as polyethylene, polypropylene, and ethylene-propylene copolymer, polymethylpentene, and polyvinyl chloride. , Polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyvinyl acetal, fluorine resin (polyvinylidene fluoride, polytetrafluoroethylene, etc.), polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polylactic acid , Polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymer, ABS resin, polyphenylene ether (PPE), modified PPE, polyamide, polyimide, polyamideimide, polyether imi , Polymethacrylic acid esters of polymethyl methacrylate, polyacrylic acids, polycarbonate, polyarylate, polyphenylene sulfide, polysulfone, polyether sulfone, polyether nitrile, polyether ketone, polyketone, liquid crystal polymers. Of these, a polyamide resin is preferable in terms of moldability, chemical resistance, and economy, polybutylene terephthalate is preferable in terms of sealing properties and adhesiveness, and polyphenylene sulfide is preferable in terms of heat resistance.

The resin composition of the present invention contains a thermally conductive filler.
The heat conductive filler used in the present invention is not particularly limited as long as it has heat conductivity, but it is preferable to use a material having a heat conductivity of 5 W / (m · K) or more. In addition, those used for the purpose of improving mechanical properties as fillers, and those used for the purpose of imparting the functions of conductivity, insulation, magnetism, piezoelectricity, and electromagnetic wave absorption have the above thermal conductivity. Can be used as a filler in the present invention.
Examples of the form of the heat conductive filler include a spherical shape, a powder shape, a fiber shape, a needle shape, a scale shape, a whisker shape, a microcoil shape, and a nanotube shape.
The thermal conductivity of the thermally conductive filler can be measured using the sintered product.

Specific examples of the thermally conductive filler (representative values of thermal conductivity in parentheses (unit: W / (m · K) are described), talc (5-10), aluminum oxide (36), Magnesium oxide (60), zinc oxide (25), magnesium carbonate (15), silicon carbide (160), aluminum nitride (170), boron nitride (210), silicon nitride (40), carbon (10 to several hundreds), Inorganic fillers such as graphite (10 to several hundred), silver (427), copper (398), aluminum (237), titanium (22), nickel (90), tin (68), iron (84), stainless steel (15) etc. These may be used independently and may use 2 or more types together.
Of the thermally conductive fillers exemplified above, graphite and boron nitride are preferably used because of their high thermal conductivity efficiency when blended with a thermoplastic resin. In terms of economy, it is preferable to use talc, aluminum oxide, magnesium oxide, magnesium carbonate, or zinc oxide. Moreover, since talc and boron nitride have electrical insulation, the electrical insulation can be imparted to the resin composition by blending them.

Examples of the form of graphite include a spherical shape, a powder shape, a fiber shape, a needle shape, a scale shape, a whisker shape, a microcoil shape, and a nanotube shape. Of these, scaly graphite is particularly preferable because it can increase the heat conduction efficiency when blended with a thermoplastic resin. The average particle size of the flaky graphite is preferably 1 to 300 μm, and more preferably 5 to 150 μm. If the average particle size is less than 1 μm, agglomerates are likely to occur due to poor dispersion, a uniform molded product cannot be obtained, and mechanical properties may be deteriorated or thermal conductivity may be varied. When the average particle diameter exceeds 300 μm, it may be difficult to fill the resin composition at a high concentration, or the surface of the molded body may become rough.

  Examples of the form of talc include a plate shape, a scale shape, a scale shape, and a flake shape. Of these, scaly talc and lamellar talc are particularly preferable because they are easily oriented in the plane direction when formed into a molded body, and as a result, the thermal conductivity can be increased. For the same reason as described above, the average particle size of the scaly talc is preferably 1 to 200 μm, and more preferably 5 to 100 μm.

  Examples of the form of boron nitride include a plate shape, a scale shape, and a flake shape. Among these, scaly boron nitride and flaky boron nitride are particularly preferable because they are easily oriented in the planar direction when formed into a molded body, and as a result, the thermal conductivity can be increased. For the same reason as described above, the average particle size of the flaky boron nitride is preferably 1 to 200 μm, and more preferably 5 to 100 μm. The crystal system of boron nitride is not particularly limited, and boron nitride having any crystal structure such as hexagonal system, cubic system, and the like is applicable. Of these, boron nitride having a hexagonal crystal structure is preferable because of its high thermal conductivity.

  Examples of the form of magnesium oxide include a spherical shape, a fiber shape, a spindle shape, a rod shape, a needle shape, a cylindrical shape, and a column shape. Among these, spherical magnesium oxide is particularly preferable because it can suppress a decrease in fluidity of the resin when blended with a thermoplastic resin. By containing magnesium oxide, thermal conductivity can be improved without reducing the insulating properties of the resin composition. For the same reason as described above, the average particle diameter of the spherical magnesium oxide is preferably 0.5 to 150 μm, and more preferably 1 to 100 μm.

  In the resin composition of the present invention, the volume ratio of the thermoplastic resin to the thermally conductive filler is preferably 20/80 to 95/5 for the thermoplastic resin and the thermally conductive filler, and 30/70 to More preferably, it is 90/10. If the blending amount of the heat conductive filler is less than 5% by volume, sufficient thermal conductivity may not be obtained, and if the blending amount exceeds 80% by volume, the fluidity is remarkably deteriorated, so The load may become too high and the operability may decrease.

  The said resin composition can be shape | molded in the shape as a resin-made heat radiating component by a well-known method. Among these, the injection molding method is preferable because it has a high degree of freedom in molding and enables high-precision processing.

  The low thermal conductivity component can form a snap fit portion and / or a screw hole portion as required. The snap-fit part is a flaky convex part provided in the main part of the board, for example, to fit a cover material that covers the heating element mounted on the board, for example, when fitting a cover material etc. The fitting part is slightly expanded and the cover material is pushed inside the snap fitting part to perform a predetermined fitting. Accordingly, the snap fit part itself may have thermal conductivity, but when the snap fit part is expanded, the toughness of the resin composition is insufficient, and thermal cracking occurs when cracking or chipping occurs. The content of the filler can be lowered or the composition can be made to contain no thermally conductive filler.

  The screw hole portion is a concave portion provided in a columnar shape, and needs to have toughness so that the screw hole portion does not break when tightening while screwing in the screw. Therefore, the screw hole part itself may have thermal conductivity, but when the screw is screwed into the screw hole part, the toughness of the resin composition is insufficient and the screw hole part is broken. Can reduce the content of the heat conductive filler, or can have a composition not containing the heat conductive filler.

The low thermal conductivity component can be formed of a thermoplastic resin containing an electrically conductive thermal conductive filler, or an electrical insulating thermal conductive filler. If the heat source and the heat radiating component are electrically insulated, generally an electrically conductive thermally conductive filler having a high thermal conductivity can be used.
However, when the heat source and the heat dissipation component are not electrically insulated, it is preferable to use an electrically insulating thermally conductive filler. Moreover, you may use what mixed the electrically insulating heat conductive filler and the electrically insulating heat conductive filler to such an extent that there is no electrical problem.
After forming a low thermal conductivity component, it can be assembled to a substrate on which a heat source such as an LED is mounted. For example, a low thermal conductivity containing talc or boron nitride directly on a predetermined portion of the substrate by injection molding Parts can also be molded. In that case, since the insulating layer can be integrated with the substrate, the heat generated by the heat generation source can be efficiently radiated through the resin heat dissipation component via the insulating layer. For example, when an insulating layer formed in a sheet shape is used, it is only disposed at a predetermined portion of the substrate, and therefore an air layer is included between the layers and heat transfer loss occurs. In order to increase the heat dissipation efficiency of the heat dissipation structure, it is particularly preferable to form an insulating layer directly on the substrate.
In addition, heat dissipation efficiency can be improved by integrally forming a layer having insulating properties directly on the substrate. On the other hand, a layer having insulating properties between an electric circuit in a heat source such as an LED and a resin heat radiating component. Therefore, electrical reliability can be improved.

After forming a low thermal conductivity component and assembling it on a substrate or the like on which a heat source such as an LED is mounted, it is combined with a resin heat radiation component by injection molding. In other words, the resin heat dissipating part should be made of a resin having a high thermal conductivity as much as possible to improve the heat dissipating property. Therefore, even if a screw part for fixing to other components is formed, if it is to be screwed, a crack will occur. Moreover, even if a structure such as a snap fit is formed, a stressed root may be broken when it is fixed. Therefore, a part made of a resin having lower thermal conductivity than that of a resin heat radiating part is sandwiched, and a screw part or a snap fit structure that requires strength and toughness is formed there.
After assembling a substrate with a heat source mounted on a low thermal conductivity component, insert it into the mold and pour a resin with high thermal conductivity into the gap between the low thermal conductivity resin and the mold. Integrate high thermal conductivity parts. The interface between the low thermal conductivity component and the high thermal conductivity component is preferably welded together. For this purpose, it is preferable that the matrix resin of the low thermal conductivity component and the matrix resin of the high thermal conductivity component have the same material amount or a combination having good adhesiveness is appropriately selected.
Furthermore, in order to increase the area for releasing heat, it is preferable to integrate with a case or the like formed of a heat conductive resin. The heat conductive resin used for the case can be appropriately selected from the viewpoints of strength, moldability, and heat dissipation. That is, when not much mechanical strength is required, it is preferable to increase the heat conductivity of the case by increasing the filling amount of the heat conductive filler as much as possible. On the contrary, when the mechanical strength of the case is necessary or the moldability is necessary, the filling amount of the heat conductive filler is decreased to increase the mechanical strength of the case or improve the moldability. It is preferable to do. It is preferable to reduce the thermal resistance of the interface by integrating the heat dissipation component and the case. It is preferable that a part in which a heat source, a low thermal conductivity part and a heat dissipation part are integrated is inserted into a mold and the case is injection-molded to weld or bond the interface.

  The method for manufacturing the heat dissipation structure of the present invention is not particularly limited. For example, the step of obtaining a low thermal conductive part having a screw part and a snap fit by injection molding, the step of assembling a heat source, and the assembly are performed. It is possible to efficiently manufacture using a manufacturing method including a step of integrating the heat generation source and the resin heat radiation component.

  The heat dissipating structure of the present invention can provide a heat dissipating structure with good heat dissipating efficiency and light weight when a heat source is mounted. For example, a lamp component mounted with an LED or a bulb bulb, or a CPU is mounted. It can be suitably used for various types of electrical and electronic components mounted with computer circuit board components and IC elements such as LSI.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Cable 3 Heat generating source 4 Heat generating member 5 Screw part 6 Snap fitting part 7 Low heat conductive component 8 Integrated product of heat generating source and low heat conductive component 9 Heat radiating component 10 Integrated component of heat generating source and heat radiating component 11 Case 12 Heat generating source And case integrated product

Claims (7)

  A heat radiating structure in which a heat source is disposed on a resin heat radiating component having thermal conductivity and a layer having a lower thermal conductivity than the resin heat radiating component on the resin heat radiating component.   2. The heat dissipation structure according to claim 1, wherein the resin heat dissipation component is made of a thermoplastic resin containing a heat conductive filler.   The heat dissipation structure according to claim 1, wherein the low thermal conductivity component has a snap fit portion and / or a screw hole portion.   The member which comprises the said snap fit part and / or a screw hole part is an electrically insulating thermoplastic resin, The heat radiating structure in any one of Claims 1-3 characterized by the above-mentioned.   The heat dissipation structure according to any one of claims 1 to 4, wherein the heat dissipation structure is an LED.   6. After obtaining a low thermal conductivity part having a snap fit part and / or a threaded hole part by injection molding, after disposing the heat source, the resin heat radiating part and the heat source are integrated. The manufacturing method of the heat dissipation structure in any one. A lamp part using the heat dissipating structure according to claim 1.