JP2008091432A - Electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic component having excellent heat radiating property even when a plurality of electronic elements are provided adjacently. <P>SOLUTION: In an electronic component 11 provided with: a heat radiating body 19 having one main surface; and electronic elements 18 such as a plurality of light emitting diodes arranged in the surface direction on the main surface of the heat radiating body 19, when a desired direction in the main surface of the heat radiating body 19 is defined as x direction, a direction perpendicular to the x direction on the main surface as a y direction, and a direction orthogonal to the same main surface as a z direction, the heat radiating body 19 is formed of a heat conductivity anisotropic carbon material or metal impregnated carbon material having relatively lower heat conductivity in the main surface direction and relatively higher heat conductivity in the z direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic component having a plurality of electronic elements arranged in a narrow area such as an LED print head or a display device.

In recent years, semiconductor light emitting diodes (LEDs) have been widely used as light emitting elements for various light sources. Usually, an LED chip is mounted on an LED container provided with a power supply lead, and is sealed with a sealing material such as a transparent resin. Various heat dissipation structures have been proposed for containers for accommodating light emitting elements in order to increase luminous efficiency and increase output. For example, Patent Document 1 discloses an optical print head in which a heat dissipation through hole penetrating from the upper surface to the lower surface is formed on a substrate provided with a plurality of light emitting element modules. Patent Documents 2 and 3 disclose a plate-like member related to a carbon-based metal composite material having a high thermal conductivity and a low thermal expansion coefficient used for a heat radiating body, and a manufacturing method thereof. In particular, Patent Document 3 discloses a plate material molded body in which molten aluminum, copper, silver or the like is pressure-impregnated. Further, Patent Document 4 presents an application of a carbon-based metal-impregnated plate material as a heat radiator, and Patent Document 5 specifically discloses the use of a metal-impregnated carbon material as a heat radiator in an LED container. The LED container disclosed in Patent Document 4 includes a plate-like high thermal conductivity carbon material and a frame-shaped metal base, and the LED chip is disposed inside the metal base frame, and directly with the high thermal conductivity carbon material. It is mounted in contact. Compared with a ceramic container, heat dissipation is improved, and luminous efficiency is improved.
Japanese Patent Laid-Open No. 10-226107 JP 2000-202973 A JP 2001-058255 A JP 2001-118960 A JP 2006-086391 A

However, in the structure described in Patent Document 1, a through hole must be formed at a position corresponding to the light emitting element, and the limit is reached in an electronic component in which a large number of electronic elements are arranged in a narrow area as in recent years. Yes. On the other hand, Patent Document 2-5 does not disclose a heat dissipation measure when a plurality of electronic elements are arranged in a narrow region. When a plurality of electronic elements are arranged in a narrow region, there is a problem that an electronic element housed alone, called thermal interference between the electronic elements. Therefore, a more excellent heat dissipation structure is required.
Therefore, an object of the present invention is to provide an electronic component having excellent heat dissipation despite having a plurality of electronic elements close to each other.

In order to solve the problem, the electronic component of the present invention is
An electronic component comprising a radiator having a main surface and a plurality of electronic elements mounted so as to be arranged in a plane direction on the main surface of the radiator, wherein an arbitrary direction on the main surface of the radiator is an x direction When the direction perpendicular to the x direction on the same principal surface is the y direction and the direction perpendicular to the principal surface is the z direction,
The radiator is made of a heat conductive anisotropic carbon material or a metal-impregnated carbon material having a relatively low thermal conductivity in the principal surface direction and a relatively high thermal conductivity in the z direction. .
In the electronic component of the present invention, the heat radiator has a low thermal conductivity in the direction of the main surface where the electronic elements are arranged, and has a high thermal conductivity in the direction orthogonal to the main surface. Is hardly transmitted to the adjacent electronic element, but is conducted in the direction of the back surface of the radiator. And it is radiated at the back side. Examples of the metal impregnated in the metal-impregnated carbon material include aluminum, copper, and silver.

  When the electronic elements are arranged one-dimensionally in the x direction, it is preferable that the heat conductivity in the main surface direction of the radiator is lowest in the x direction. This is because thermal interference between electronic elements is most effectively prevented. Further, when the electronic elements are two-dimensionally arranged in the x direction and the y direction, the heat conductivity in the main surface direction of the radiator is the lowest in the y direction, and the electronic elements in the x direction in the radiator are It is preferable that a groove is formed between them. This is because thermal interference between adjacent electronic elements is prevented by the low thermal conductivity of the radiator itself in the y direction and by the heat insulating action of the grooves in the x direction. More preferably, a heat insulating member having a lower thermal conductivity than the carbon material and the metal-impregnated carbon material is disposed in the groove. The groove may be formed on either the main surface or the back surface of the radiator.

A convex portion may be formed on the back surface of the heat radiating body, or a heat radiating member having a higher thermal conductivity than the carbon material and the metal-impregnated carbon material may be intermittently fixed. This is because the heat dissipation area increases.
Depending on the embodiment, the surface of the radiator may be plated with Ni or the like, or may be covered with an electrically insulating film.

  As described above, the heat generated by the electronic element is hardly transmitted to the adjacent electronic element, but is conducted in the direction of the back surface of the heat radiating body. Therefore, the electronic component of the present invention has a plurality of electronic elements close to each other. Nevertheless, it has excellent heat dissipation. Therefore, when the electronic element is a semiconductor element, it is possible to achieve a small size and high output by arranging the elements in a matrix to form an element array. Further, when the electronic element is used as a light emitting element in an LED print head and an insulating container that houses the light emitting element is integrated with a heat radiating body, the difference in thermal expansion between the two becomes small, preventing warping of the insulating container. it can. As a result, the printing accuracy is improved.

Embodiment 1
An electronic component according to a first embodiment of the present invention will be described with reference to FIGS. The electronic component 11 includes a plate-like heat radiator 19, an insulating container 14, and an electronic element 18 made up of a light emitting diode. The insulating container 14 is composed of a lower substrate 12 and an upper substrate 13 each having a large number of through-holes made of insulating ceramic and formed in a line in the surface direction (x direction). The lower substrate 12 is fixed on the main surface of the radiator 19, and the upper substrate 13 is laminated thereon. The hole of the upper substrate 13 is larger than that of the lower substrate 12, and has an annular step between the inner peripheral surface of the hole of the upper substrate 13 and that of the lower substrate 12. The upper and lower substrates 12 and 13 are each formed by a known sheet forming method, and then a wiring pattern (not shown) is printed, stacked on each other, and baked to be integrated. A mounting space for the electronic element 18 is formed by joining the heat radiating body 19 to the obtained insulating container 14.

  The electronic elements 18 are mounted on the main surface of the heat dissipating body 18 with the same pitch as the holes so that the light emitting surface faces upward, and individually on the inner peripheral surfaces of the holes of the upper and lower substrates 12 and 13. being surrounded. One end of the wire 17 is bonded to the surface of the electronic element 18 and the other end is bonded to an unillustrated internal pad exposed at the annular step so that the electronic element 18 can be electrically connected to an external circuit. Has been. The mounted electronic element 18 is sealed and simultaneously sealed by filling the remaining space surrounded by the heat radiator 19 and the holes of the upper and lower substrates 12 and 13 with the translucent resin sealing material 16. The

  The heat dissipating body 19 is made of a carbon material having a heat conduction anisotropy or a metal-impregnated carbon material, and the direction having the highest thermal conductivity coincides with the vertical (z-axis) direction with respect to the upper and lower substrates 12 and 13 and the lowest heat conduction. It is mounted so that the direction having the rate coincides with the x-axis direction. The metal-impregnated carbon material is obtained, for example, by molding and firing carbon powder or carbon fiber and impregnating a metal such as Ag, Cu, or A1. The thermal conductivity differs depending on the direction, and is 540 W / (m · K), which is the highest in the direction (z-axis direction) transmitted by the lattice vibration of the two-dimensional crystal plane of carbon, and 140 W / (m · K) in the x-axis direction. 450 W / (m · K) in the y-axis direction. This type of high thermal conductive carbon material has some differences depending on the firing method and the difference of impregnated metal, but the thermal expansion coefficient is 6-10 ppm / ° C., which is very close to the thermal expansion coefficient of a semiconductor such as ceramic, Si, GaAs, The Young's modulus is low, so that it is well bonded to the electronic element 18 and the insulating container 14.

  According to the electronic component 11, since the heat conductivity of the radiator 19 is the lowest in the x-axis direction in which the electronic elements 18 are arranged and the highest in the z-axis direction, the heat generated by the electronic elements is transmitted between the adjacent electronic elements 18. It is difficult to transmit from the back surface of the electronic element 18 to the back surface of the radiator 19 preferentially and promptly.

Embodiment 2
As shown in FIG. 3 as a perspective view, and FIGS. 4 and 5 as an XX sectional view and a YY sectional view of FIG. An insulating container 34 and an electronic element 38 made of a light emitting diode are provided. As in the first embodiment, the insulating container 34 includes the lower substrate 12 and the upper substrate 13 made of insulating ceramic. Only the differences from the first embodiment will be described in detail below. First, unlike the first embodiment in which the holes for accommodating the electronic elements 18 are arranged in one direction, in this embodiment, the lower substrate 12 and the upper substrate 13 are formed in a matrix in the vertical and horizontal directions in plan view. The electronic elements 38 are individually accommodated in the mounting spaces surrounded by the holes and the radiator 39.

  The heat dissipating body 39 may be a carbon material or metal-impregnated carbon material having the same thermal conductivity as that in the first embodiment, but the heat conductivity is lowest in the y-axis direction and highest in the z-axis direction. In this case, a groove 40 such as a notch is formed at a boundary portion between adjacent electronic elements 38 in the x-axis direction. The opening of the groove 40 is closed by the lower substrate 32. The inside of the groove 40 is made of air having a lower thermal conductivity than that of carbon, so that it is insulated as a heat transfer resistance in the x-axis direction. Therefore, the heat generated by the electronic elements is not easily transmitted between the adjacent electronic elements 38 due to the relatively low thermal conductivity of the radiator 39 itself in the y-axis direction, and due to the heat insulating action of the groove 40 in the x-axis direction. It is transmitted preferentially and promptly from the back surface of the electronic element 38 toward the back surface of the radiator 39. A reduction in luminous efficiency due to the temperature rise of the light emitting diode is suppressed, and a large number of light emitting diodes are collectively arranged to achieve high output.

  Instead of the groove 40, a groove 50 opened on the back surface side of the radiator 39 may be provided as shown in FIG. In this case, the thermal resistance in the x-axis direction is slightly weaker than that of the groove 40, but is offset by increasing the surface area and improving heat dissipation. Further, as shown in FIG. 7, the heat radiation area may be increased by integrally providing a convex portion 60 at a position corresponding to the electronic element 38 on the back surface of the heat radiator 39. The convex portion 60 may be fixedly formed separately from the radiator 39.

A 10 × 10 × 1 mm plate in which a carbon material was impregnated with copper was prepared as a radiator. The specific gravity is 2.7 g / cc, and the bending strength, Young's modulus, thermal conductivity, thermal expansion coefficient, and electrical resistivity are 80 MPa, 25 GPa, 450-540 W / mK, and 0.2, respectively, in the direction of the two-dimensional crystal plane of carbon. They were 1 ppm / ° C. and 200 μΩ · cm, respectively, 13 MPa, 7 GPa, 140 W / mK, 10 ppm / ° C., and 600 μΩ · cm in the vertical direction. Ni electrolytic plating was applied to the surface of the radiator. Separately, a ceramic insulator formed with a wiring pattern was prepared.
A ceramic insulator was bonded onto the main surface of the heat radiating body, and two 1 mm square two blue LED elements were mounted with a silver paste at an interval of about 3.5 mm. And the electronic component of the Example was created by connecting the LED element and the wiring pattern on a ceramic insulator with a gold wire.
For comparison, an electronic component of a comparative example was created under the same conditions as the electronic component of the example except that a surface of a copper plate subjected to Ni electrolytic plating was used as a heat radiator instead of the copper-impregnated carbon material.

  When these electronic components were energized and the temperature of the LED element surface was measured while changing the energization current between 0-350 mA, the surface temperature increased similarly to the current value. Further, when the energization current was fixed at 350 mA and the time-dependent changes in the surface temperature of the LED element and the radiator were measured, no difference was found between the example and the comparative example. Next, when the temperature of the other LED element was measured when one of the two LED elements was energized, the thermal effect of the example on the adjacent element was less than that of the comparative example as shown in FIG. .

It is sectional drawing which shows the principal part of the electronic component of Embodiment 1 which concerns on this invention. It is a perspective view of the state before sealing with a sealing material in the principal part which shows the electronic component. 6 is a perspective view showing an electronic component of Embodiment 2. FIG. FIG. 4 is a cross-sectional view of the electronic component of FIG. 3 taken along line XX. FIG. 4 is a cross-sectional view taken along line YY of the electronic component of FIG. 3. FIG. 10 is a cross-sectional view showing a modification of the second embodiment. 10 is a cross-sectional view showing another modification of the second embodiment. FIG. It is a graph which shows the result of having measured the other temperature when it supplies with electricity to one of two adjacent LED elements.

Explanation of symbols

11, 31; electronic parts 12, 32; lower substrates 13, 33; upper substrates 17, 37; wires 19, 39; radiators 14, 34; insulating containers 16, 36; 50; groove 60; convex portion

Claims (6)

An electronic component comprising a radiator having a main surface and a plurality of electronic elements mounted so as to be arranged in a plane direction on the main surface of the radiator, wherein an arbitrary direction on the main surface of the radiator is an x direction When the direction perpendicular to the x direction on the same principal surface is the y direction and the direction perpendicular to the principal surface is the z direction,
The radiator is made of a heat conductive anisotropic carbon material or a metal-impregnated carbon material having a relatively low thermal conductivity in the principal surface direction and a relatively high thermal conductivity in the z direction. Electronic components.   The electronic component according to claim 1, wherein the electronic elements are arranged one-dimensionally in the x direction, and the thermal conductivity in the main surface direction of the heat radiating body is lowest in the x direction.   The electronic elements are two-dimensionally arranged in the x direction and the y direction, the thermal conductivity in the main surface direction of the radiator is the lowest in the y direction, and a groove is formed between the electronic elements in the x direction in the radiator. The electronic component according to claim 1, wherein the electronic component is formed.   The electronic component according to claim 2, wherein a heat insulating member having a lower thermal conductivity than the carbon material and the metal-impregnated carbon material is disposed in the groove.   5. The electronic component according to claim 3, wherein the groove is formed on a main surface or a back surface of the radiator.   6. A convex portion is formed on the back surface of the heat radiating body, or a heat radiating member having a higher thermal conductivity than the carbon material and the metal-impregnated carbon material is intermittently fixed. Electronic components described in

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