JP2017162575A - Heat radiation structure of light source unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a heat transmission amount from a light source unit to a circuit board, to enhance heat radiation efficiency of a semiconductor light-emitting element and to prolong the life of the light source unit.SOLUTION: At a light source unit 4, heat radiation parts 22, 23 are provided for extracting heat generated by an LED 3 to a circuit board 2 side. At the circuit board 2, a wiring pattern 14 for supplying power to the LED 3, and a heat receiving part 17 for receiving the heat generated by the LED 3 from the heat generation parts 22, 23 are provided. A heat conductive member 20 is interposed between the heat radiation parts 22, 23 and the heat receiving part 17. A terminal hole 16 formed at one part of the wiring pattern 14 functions as a heat receiving part, and a press fit terminal 25 press-fitted into the terminal hole 16 functions as the heat radiation part. In a vehicular lighting fixture, a three-dimensional substrate can be used as the circuit board, and a plurality of light source units can be arranged on the three-dimensional substrate in a three-dimensional manner.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a heat dissipation structure for releasing heat generated by a semiconductor light emitting element toward a circuit board in a light source unit including the semiconductor light emitting element.

  2. Description of the Related Art Conventionally, a heat dissipation structure that extracts heat generated from a semiconductor light emitting element to a circuit board using a brazing material used for mounting a light source unit is known. For example, in the heat dissipation structure 81 shown in FIG. 9, the light source unit 83 including the LEDs 82 is attached to the wiring pattern 86 on the circuit board 85 with the solder 84, and heat generated from the LEDs 82 is transmitted to the solder 84 and taken out to the wiring pattern 86. The light is discharged from the substrate 85 to the periphery. Patent Document 1 proposes a technique for preventing LED misalignment due to solder reflow in a heat dissipation structure using solder.

Japanese Patent Laid-Open No. 2015-56228

  According to the conventional heat dissipation structure, there is an advantage that the brazing material for mounting the light source unit can be used for heat dissipation. However, since the joining area of the brazing filler metal itself is relatively small, there is a problem that the amount of heat transfer from the light source unit to the circuit board is limited, and the life of the light source unit is shortened by heat storage. In addition, it is conceivable to increase the amount of brazing material used in order to increase the amount of heat transfer, but this causes another problem that the mounting position of the light source unit tends to shift with reflow.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat dissipation structure that can increase the heat dissipation efficiency and extend the life of the light source unit without causing a positional shift of the light source unit.

  In order to solve the above-described problems, a heat dissipation structure of the present invention includes a light source unit provided with a semiconductor light emitting element and a circuit board that supports the light source unit, and the light source unit generates heat from the semiconductor light emitting element on the circuit board side. It includes a heat radiating part that emits, and a circuit board includes a power feeding part that supplies power to the semiconductor light emitting element, and a heat receiving part that receives heat generated from the semiconductor light emitting element from the heat radiating part.

  Here, the heat radiation part on the light source unit side and the heat receiving part on the circuit board side are not limited to a specific shape or configuration. For example, the light source side terminal is used as a heat radiating portion, the substrate side terminal is used as a heat receiving portion, and at least one of the light source side terminal and the substrate side terminal is provided with a pressure contact portion that is elastically deformed by contact with the other. The light source unit can be configured to be held on the circuit board by the elastic restoring force. In this way, the heat radiating section and the heat receiving section can be used not only as heat transfer means but also as mounting means, and the light source unit can be mounted on the circuit board easily and with high positional accuracy.

  Moreover, it is preferable to interpose a heat conductive member between the heat radiation part of the light source unit and the heat receiving part of the circuit board so that higher heat radiation efficiency can be obtained. In terms of providing a heat dissipation structure at a low cost, it is also desirable to use a printed circuit board as a circuit board and include a power feeding unit and a heat receiving unit in the wiring pattern of the printed circuit board. In this case, a terminal hole formed in a part of the wiring pattern can function as a heat receiving portion of the circuit board, and a press-fit terminal press-fitted into the terminal hole can function as a heat radiating portion of the light source unit.

  As a circuit board, it is not limited to a specific board | substrate, For example, various board | substrates according to the use of a light source unit, such as a rigid board | substrate, a flexible substrate, a plane substrate, a solid board | substrate, can be used. For example, in the case of a vehicular lamp in which a plurality of light source units are arranged three-dimensionally in a lamp chamber, the plurality of light source units are different as circuit boards so that each unit can be positioned with high accuracy and ease. A three-dimensional substrate supported at a position is used, and a wiring pattern common to at least two light source units is provided on the three-dimensional substrate, and a heat receiving portion for each light source unit can be provided on the wiring pattern.

  According to the heat dissipation structure of the present invention, since the heat generation of the semiconductor light emitting element is configured to be guided from the heat dissipation part of the light source unit to the heat receiving part of the circuit board, the amount of heat transfer from the light source unit to the circuit board is increased, There is an excellent effect that the heat radiation efficiency is increased and the life of the light source unit can be extended. In addition, since it is not necessary to use a brazing material such as solder for heat dissipation, it is possible to prevent the light source unit from being displaced due to reflow.

It is a top view of the illumination module which shows one Embodiment of this invention. It is the II-II sectional view taken on the line of FIG. 1 which shows the thermal radiation structure of Example 1. FIG. It is a top view and an elevation view of a light source unit. It is an elevation view which shows the modification of a light source side terminal. It is a perspective view which shows the thermal radiation structure of Example 2. FIG. It is sectional drawing which shows the thermal radiation structure of Example 2. FIG. It is a perspective view which shows the thermal radiation structure of Example 3. FIG. It is sectional drawing which shows the heat dissipation structure of Example 3. It is sectional drawing which shows the conventional heat dissipation structure.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The illumination module 1 shown in FIG. 1 includes, for example, a circuit board 2 provided in a lamp body (not shown) of a vehicle lamp. On the circuit board 2, a plurality of light source units 4 including LEDs 3 as semiconductor light emitting elements are mounted, and a connector connected to an external power source (not shown) such as an in-vehicle battery, for example, a card edge connector 5 is provided. It has been. The card edge connector 5 is electrically connected to the LEDs 3 of each light source unit 4 via a wiring pattern 14 (see FIG. 2) on the circuit board 2 so that the circuit board 2 supplies power input from an external power source to the plurality of LEDs 3. It has become.

  As the circuit board 2, FIG. 1 representatively shows a planar substrate of Example 1 described below, but a three-dimensional substrate described in Examples 2 and 3 can also be used. Moreover, the illumination module 1 is not limited to a vehicle lamp, It can also be used for the illuminating device for houses, etc. In addition to the LED 3, a semiconductor laser can be used for the semiconductor light emitting element of the light source unit 4. Hereinafter, the heat dissipation structure of the light source unit 4 will be described in detail with some examples.

  First, a first embodiment of the present invention will be described with reference to FIG. 2, FIG. 3, and FIG. As shown in FIG. 2, in the heat dissipation structure 11 of Example 1, the circuit board 2 is formed in a planar shape with an insulating material, the light source unit 4 is mounted on the surface of the circuit board 2, and the heat dissipation sheet is mounted on the back surface of the circuit board 2. The heat sink 13 is combined through 12. The circuit board 2 is a rigid printed board. A wiring pattern 14 as a power feeding portion is formed on both front and back surfaces by copper plating, and most of the wiring pattern 14 is covered with a resist 15 made of an electrically insulating material.

  The light source unit 4 includes a resin package 19 that houses the LED (chip) 3. The LED 3 is sealed inside the package 19 with a fluorescent material mixed resin 21, and an opening 19 a for releasing the heat of the LED 3 is formed at the bottom of the package 19. The electrode 19 of the LED 3, that is, the cathode 22 and the anode 23 are exposed in the opening 19 a, and these function as a heat radiating part that emits the heat generated by the LED 3 to the circuit board 2 side.

  The resist 15 on the circuit board 2 has been removed from the region where the light source unit 4 is mounted and its peripheral region. The removed portion of the wiring pattern 14 is provided with a plurality of terminal holes 16 and a heat receiving copper foil portion 17, which function as heat receiving portions that receive the heat generated by the LEDs 3 from the heat radiating portion on the light source unit 4 side. The terminal hole 16 is a through hole whose inner surface is covered with the same copper plating as the wiring pattern 14, and is electrically connected to the card edge connector 5 via the wiring pattern 14.

  A heat conductive member 20 made of a heat radiating pad or heat radiating grease is provided in the opening 19 a of the light source unit 4. The heat conductive member 20 is interposed between the electrodes 22 and 23 of the LED 3 and the heat receiving copper foil portion 17 in a state where movement is restricted by the peripheral surface of the opening 19a. A part of the heat generated by the LED 3 is conducted from the electrodes 22 and 23 to the heat receiving copper foil portion 17 through the heat conductive member 20, and the wiring pattern 14 and the heat dissipation sheet 12 of the circuit board 2 are transmitted from the heat receiving copper foil portion 17. Is transmitted to the heat radiating plate 13 and is emitted around the lighting module 1.

  In addition, as the heat conductive member 20, a material having higher heat conductivity than the circuit board 2 can be used, and preferably 0.2 W / mk or more higher than that of a general glass / epoxy resin substrate (FR-4). A solid or liquid material having a thermal conductivity of can be used. More preferably, the heat conductive member 20 can be formed of a metal material. A heat-dissipating adhesive is interposed between the cathode 22 and the anode 23 which are electrodes of the LED 3 and the heat conductive member 20, and heat generated by the LED 3 is transmitted to the heat conductive member 20, so that the heat conductive member 20 and the circuit board 2 receive heat. A heat-dissipating adhesive may be interposed between the copper foil portions 17 and the heat of the heat conductive member 20 may be transmitted to the wiring pattern 14. In addition, a material having a thermal conductivity comparable to that of the heat conductive member 20 can be preferably used for the resist 15 covering the wiring pattern 14. In order to prevent a short circuit from occurring on the back side of the package 19, the heat receiving copper foil portion 17 is divided into two in accordance with the electrode position of the LED 3, and a gap for preventing migration of 0.1 mm or more is set between the two. May be interposed.

  The electrode of the LED 3, that is, the anode 23 and the cathode 22 are connected to a press-fit terminal 25 that is a terminal on the light source unit 2 side, and the light source side terminal 25 emits heat of the LED 3 together with the electrodes 22 and 23 to the circuit board 2 side. Functions as a heat dissipation part. As shown in FIG. 3A, the press-fit terminals 25 are formed so as to protrude downward in different numbers on the two opposite sides of the package 19 so as not to mistake the polarity when the light source unit 4 is mounted. It is press-fitted into the terminal hole 16. Further, the press-fit terminal 25 of the first embodiment has an L-shaped or U-shaped lead frame structure like the semiconductor package, and the lead frame prevents the package 19 from being directly pressurized when mounted on the circuit board 2. The shoulder portion protrudes outward from the package 19.

  As shown in FIG. 3B, a press contact portion 26 is formed in an elongated annular shape at the tip or lower end of each press-fit terminal 25. Then, in a state where the press-fit terminal 25 is press-fitted into the terminal hole 16, the press contact portion 26 comes into contact with the inner surface (copper plating portion) of the terminal hole 16 and is elastically deformed in a direction orthogonal to the mounting direction P of the light source unit 4. The mounted light source unit 4 (see FIG. 2) is held on the circuit board 2 by the elastic restoring force of the pressure contact portion 26, and part of the heat generated by the LED 3 is transferred from the light source unit 4 via the press-fit terminal 25 to the circuit board. 2 has been communicated. In addition, it is preferable to provide the press-contact part 26 so that the lower end thereof does not protrude from the terminal hole 16 to the lower side of the circuit board 2, and when the heat sink 13 is installed on the lower side of the circuit board 2, It is desirable to provide it within 0.1 mm or more from the lower surface inside the terminal hole 16.

  Specifically, as shown in FIG. 4A, a stopper 27 that determines the insertion limit position of the press contact portion 26 can be provided at the base portion of the press fit terminal 25. Moreover, the shape of the press-contact part 26 is not limited to an annular shape, and may be a substantially U-shape with a part opened as shown in FIG. Further, in order to absorb the difference in thermal expansion between the circuit board 2 and the package 19, a bent portion 28 is cut out at the base of the press-fit terminal 25 as shown in FIG. Misalignment can also be prevented.

  According to the heat dissipation structure 11 of the first embodiment configured as described above, the heat generated by the LED 3 is led from the electrodes 22 and 23 and the press-fit terminal 25 to the heat receiving copper foil portion 17 and the terminal hole 16. Compared with the heat dissipation structure by brazing filler metal joining, the amount of heat transfer from the light source unit 4 to the circuit board 2 can be increased, and the heat dissipation efficiency can be greatly increased. Further, since the light source unit 4 is firmly held on the circuit board 2 by the press-fit terminal 25 which is also a heat radiating portion by the elastic restoring force of the pressure contact portion 26, the light source unit can be used without using a soldering material such as solder. There is also an advantage that the positional shift of 4 can be surely prevented.

  Next, a second embodiment of the present invention will be described with reference to FIGS. In the heat dissipation structure 31 of the second embodiment, a three-dimensional board 32 is used as a circuit board of the illumination module. In vehicle lamps such as headlamps and rear lamps, a resinous MID (Molded Interconnect Device) substrate can be preferably used as the three-dimensional substrate 32, and a plurality of light source support portions 34 are formed on the substrate 32 so as to have different heights. ing. The light source unit 35 is supported by each light source support portion 34 and is held on the three-dimensional substrate 32 by press-fit terminals 36.

  The light source unit 35 is configured by mounting an LED package 38 and an electronic component 39 (capacitor, resistor, etc.) on a rigid PCB (printed circuit board) 37. A light source side wiring pattern 45 is formed on both the front and back surfaces of the PCB 37, and through holes 40 as light source side terminals are provided at two locations thereof. In addition, a heat radiating portion 46 (see FIG. 6) that emits heat generated by the LED package 38 to the three-dimensional substrate 32 side is provided on the back surface side portion of the light source side wiring pattern 45.

  Each light source support portion 34 of the three-dimensional substrate 32 is provided with a plurality of through holes 41 as substrate side terminals that are electrically connected to the light source side through holes 40 through press-fit terminals 36, and each through hole 41. A board-side wiring pattern 42 for supplying electric power to is formed. The board-side wiring pattern 42 is formed with a copper foil portion 47 as a heat receiving portion at a portion facing the heat radiating portion 46 of the light source unit 35, and the heat conductive member 20 is disposed on the heat receiving copper foil portion 47. ing.

  On the other hand, the press-fit terminal 36 is provided with a first pressure contact portion 43 that is press-fitted into the light source side through hole 40 and a second pressure contact portion 44 that is press-fitted into the substrate side through hole 41. The light source unit 35 is held on the three-dimensional substrate 32 by the elastic restoring force. In the illustrated example, the wiring pattern 42 functions as a power feeding unit common to the three light source units 35, and the heat receiving copper foil portion 47 and the heat conductive member 20 are separately provided in each light source unit 35. Heat is released from the light source unit 35 to the three-dimensional board 32 every 34.

  Therefore, according to the heat dissipation structure 31 of Example 2, the heat-receiving copper contained in the board-side wiring pattern 42 from the heat-radiating part 46 included in the light source-side wiring pattern 45 through the heat conductive member 20 is generated from the LED package 38. The LED package 38 can be efficiently cooled by being guided to the foil portion 47 and increasing the amount of heat conduction from the light source unit 35 to the three-dimensional substrate 32. In addition, since the press-fit terminal 36 firmly holds the light source unit 35 on the three-dimensional board 32 by the elastic restoring force of the press-contact portion 26, the plurality of LED packages 38 can be accurately three-dimensionally arranged at different positions. it can. Moreover, since heat is radiated for each light source unit 35, the light source unit 35 having a high heat radiating function can be made a standard part, and the cost of parts can be reduced by mass production.

  Next, Embodiment 3 of the present invention will be described with reference to FIGS. In the heat dissipation structure 51 of the third embodiment, as in the second embodiment, the three-dimensional board 32 is used as the circuit board, and the plurality of light source units 52 are supported by the light source support portions 34 of the three-dimensional board 32 at different height positions. . Unlike the second embodiment, the light source unit 52 includes a thin box-shaped resin base 53 having an open bottom surface, and the base ends of a pair of leaf springs 54 are embedded in the resin base 53. The leaf spring 54 is formed of a conductive material such as a copper alloy, its base end is electrically connected to a pair of electrode portions (not shown) of the LED package 38, the light source side terminal 55 is provided at the tip exposed portion, and the plate An intermediate portion of the spring 54 serves as a heat radiating portion 60 (see FIG. 8) that emits heat from the LED package 38 to the three-dimensional substrate 32 side.

  On the other hand, each light source support portion 34 of the three-dimensional substrate 32 is formed with a substrate side terminal 56 that is separately electrically connected to the light source side terminal 55, and wiring as a power supply unit that supplies power to each substrate side terminal 56. A pattern 57 is formed. In the wiring pattern 57, a copper foil portion 61 as a heat receiving portion is formed at a portion facing the heat radiating portion 60 of the light source unit 52, and the heat conductive member 20 is disposed on the heat receiving copper foil portion 61. .

  An opening 59 is provided in the substrate side terminal 56 and the light source support portion 34, and a pressure contact portion 58 that can be inserted into the opening 59 is formed by bending inside the light source side terminal 55. Then, the base 53 of the light source unit 52 is attached to the light source support part 34 of the three-dimensional board 32, the pressure contact part 58 is elastically deformed by contact with the board side terminal 56, and is hooked on the opening 59. The light source unit 52 is held on the three-dimensional board 32 by the restoring force, and in this state, the heat generated by the LED package 38 is led from the heat radiating part 60 to the three-dimensional board 32 through the heat conductive member 20 and the heat receiving copper foil part 61. It is configured.

  Therefore, according to the heat radiating structure 51 of the third embodiment, in addition to the heat radiating effect similar to that of the second embodiment, the light source unit 52 is engaged with the pressure contact portion 58 of the light source side terminal 55 in the opening 59 of the substrate side terminal 56. Is firmly held on the three-dimensional substrate 32, and the plurality of LED packages 38 can be accurately three-dimensionally arranged at different positions, and the standardized light source unit 52 can be highly accurately and inexpensively arranged at a plurality of positions on the three-dimensional substrate 32. It can also be implemented.

  In addition, this invention is not limited to the said embodiment, For example, changing the shape of the thermal radiation part of the light source unit 4 or the heat receiving part of the circuit board 2 suitably, or the light source support part 34 of the three-dimensional board | substrate 32 It is also possible to change the shape and configuration of each part as appropriate without departing from the spirit of the invention, such as changing the angle, direction, or number.

1 Lighting Module 2 Circuit Board 3 LED
4 Light source unit 11 Heat dissipation structure of light source unit (Example 1)
14 Wiring Pattern 16 Terminal Hole 17 Heat-Receiving Copper Foil Part 20 Thermal Conductive Member 25 Press-Fit Terminal 26 Press-Contact Part 31 Heat Dissipation Structure of Light Source Unit (Example 2)
32 Three-dimensional board 35 Light source unit 36 Press fit terminal 38 LED package 40 Light source side through hole 41 Board side through hole 42 Board side wiring pattern 45 Light source side wiring pattern 46 Heat radiation part 47 Heat receiving copper foil part 51 Heat radiation structure of light source unit (implementation) Example 3)
52 Light Source Unit 54 Leaf Spring 55 Light Source Side Terminal 56 Board Side Terminal 57 Wiring Pattern 60 Heat Dissipation Part 61 Heat Receiving Copper Foil Part

Claims (6)

  A light source unit provided with a semiconductor light emitting element; and a circuit board that supports the light source unit, wherein the light source unit includes a heat dissipation part that emits heat generated by the semiconductor light emitting element to the circuit board side, and the circuit board includes: A heat dissipation structure, comprising: a power supply unit that supplies power to the semiconductor light emitting element; and a heat receiving unit that receives heat generated by the semiconductor light emitting element from the heat dissipation unit.   The heat dissipation structure according to claim 1, wherein a heat conductive member is interposed between the heat dissipation part of the light source unit and the heat receiving part of the circuit board.   The heat dissipation structure according to claim 1 or 2, wherein the circuit board includes a printed circuit board, and the power feeding unit and the heat receiving unit are included in a wiring pattern of the printed circuit board.   The heat dissipation structure according to claim 3, wherein the heat receiving portion of the circuit board includes a terminal hole formed in a part of the wiring pattern, and the heat dissipation portion of the light source unit includes a press-fit terminal that is press-fitted into the terminal hole.   4. The heat dissipation structure according to claim 3, wherein the heat receiving portion of the circuit board includes a substrate side terminal formed on a part of the wiring pattern, and the heat dissipation portion of the light source unit includes a light source side terminal that elastically contacts the substrate side terminal.   The circuit board includes a three-dimensional board that supports a plurality of light source units at different positions, the three-dimensional board includes a wiring pattern common to at least two light source units, and the wiring pattern has a separate heat receiving unit for each light source unit. The heat dissipation structure according to any one of claims 1 to 5.

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