JP2013251337A - Printed circuit board and vehicle lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for enhancing heat dissipation of a light-emitting element in a printed circuit board on which the light-emitting element and a heat sink are mounted.SOLUTION: A printed circuit board 50 includes: a substrate whose surface is insulated; a conductor layer 56 constituting a circuit pattern on the substrate; a light-emitting element 52 electrically connected to the circuit pattern; a heat dissipation path 57 which is in contact with the light-emitting element 52 and is insulated from the circuit pattern; and a heat sink 68 arranged so as to come into direct contact with the heat dissipation path 57.

Description

  The present invention relates to a printed circuit board on which a light emitting element is mounted, and a vehicular lamp using the printed circuit board.

  A light emitting element such as an LED (Light Emitting Device) is widely used as a light source of a vehicular lamp. When the temperature of the light emitting element is significantly increased, there arises a problem that the light output is reduced and the life of the element is reduced. Therefore, it is necessary to efficiently dissipate heat generated from the light emitting element. For example, in Patent Document 1, a heat conduction part is provided between the LED and the drive circuit to conduct heat from the LED to the drive circuit board side, and a heat conduction member embedded in the through hole of the drive circuit board; A light-emitting device configured to be thermally coupled to a heat conducting unit via a metal layer is disclosed.

JP 2008-66454 A

  In the technique described in Patent Document 1, since the heat conducting member is embedded in the through hole of the drive circuit board, the arrangement and size of the heat conducting member are limited.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for improving heat dissipation of a light emitting element in a printed board on which the light emitting element and a heat sink are mounted.

  One embodiment of the present invention is a printed board including an insulating substrate, a circuit pattern on the insulating substrate, and a light emitting element electrically connected to the circuit pattern. A heat dissipation path in contact with the light emitting element and insulated from the circuit pattern is formed on the printed circuit board, and further includes a heat sink disposed so as to be in direct contact with the heat dissipation path.

  According to this aspect, heat is directly transferred from the light emitting element to the heat sink via the heat dissipation path, so that the heat dissipation of the light emitting element can be improved.

  A heat sink may be arranged so as not to block light emitted from the light emitting element. Thereby, a light emitting element and a heat sink can be arrange | positioned on the same side of a board | substrate, without reducing light quantity.

  A part of the surface of the heat sink may be configured as a reflection surface of light emitted from the light emitting element. According to this, light distribution control using the reflective surface of the heat sink can be performed.

  You may provide the some light emitting element comprised so that lighting-off was possible separately.

  A vehicular lamp in which a printed board is erected in a substantially vertical direction in the lamp chamber may be configured, and a heat sink may be disposed above the light emitting element. According to this, when the vehicular lamp is used as a high beam, it is possible to make a wide light distribution below the horizon, and to improve the visibility of the road surface.

  According to the present invention, in the printed circuit board on which the light emitting element is mounted, heat is conducted from the light emitting element to the heat sink through the heat dissipation path without interposing an insulating layer, thereby improving the heat dissipation of the light emitting element. it can.

It is sectional drawing of the aluminum substrate by which the light emitting element based on the prior art was surface-mounted. (A) is sectional drawing of the aluminum substrate with which the light emitting element was surface-mounted based on one Embodiment of this invention, (b) is the top view. It is a figure which shows the example which uses the aluminum substrate carrying the light emitting element shown in FIG. 2 as a light source of a vehicle lamp. It is a figure which shows another example which uses the aluminum substrate carrying the light emitting element shown in FIG. 2 as a light source of a vehicle lamp. (A) shows an example of a light distribution pattern formed when an aluminum substrate is erected so that the heat sink is located below the light emitting element, and (b) shows that the heat sink is located above the light emitting element. It is a figure which shows the example of the light distribution pattern formed when an aluminum substrate is stood upright.

  FIG. 1 is a cross-sectional view of an aluminum substrate 10 on which a light emitting element 12 is surface-mounted, according to the prior art. An insulating layer 18 is formed on the metal base 20 made of aluminum, and a conductor layer 16 such as a copper foil is disposed on the insulating layer 18 so as to form a desired circuit pattern. An insulating layer 14 is further formed on the conductor layer 16. In the packaged light emitting element 12 such as an LED, an electrode (not shown) on the lower surface of the package is connected to the conductor layer 16 via the solder 13. A heat sink 22 for dissipating heat generated from the light emitting element 12 is disposed on the lower surface of the metal base 20.

  Since the aluminum substrate as shown in FIG. 1 has a structure well known to those skilled in the art, a detailed description of the manufacturing method and the like will be omitted.

  As shown in FIG. 1, when the heat sink 22 is disposed on the opposite side of the light emitting element 12 with the substrate interposed therebetween, an insulating layer is interposed in the heat transfer path from the light emitting element 12 to the heat sink 22, so that the heat dissipation performance is deteriorated. There is a problem.

  When a glass epoxy substrate is used as the substrate, a through hole is formed around the light emitting element, and heat generated from the light emitting element is transmitted to the heat sink on the back surface of the substrate through the through hole. Also in this case, since the insulating layer is interposed in the heat transfer path, the heat dissipation performance is deteriorated as described above.

  FIG. 2A is a cross-sectional view of an aluminum substrate 50 on which a light-emitting element 52 is surface-mounted according to an embodiment of the present invention, and FIG. 2B is a top view thereof.

  An insulating layer 58 is formed on a metal base 60 made of aluminum, and a conductor layer 56 made of a metal such as copper foil is disposed on the insulating layer 58 so as to form a desired circuit pattern. An insulating layer 54 is further formed on the conductor layer 56. An electrode (not shown) on the lower surface of the package of the light emitting element 52 such as a packaged LED is connected to the conductor layer 56 via the solder 53.

  On the insulating layer 58, a heat radiation path 57 insulated from the circuit pattern of the conductor layer 56 is formed. The heat dissipation path 57 may be the same material as the conductor layer 56 or may be a different material. The heat radiation path 57 and the conductor layer 56 may be formed simultaneously by etching or the like, or may be formed separately.

  A heat sink 62 is disposed on the substrate on the same side as the light emitting element 52 so as to be in direct contact with the heat dissipation path 57.

  On the lower surface of the light emitting element 52, a thermal pad 64 for heat transfer insulated from the electrode is provided, and the light emitting element 52 is disposed so that the thermal pad 64 and the heat radiation path 57 are in contact with each other.

  According to the above configuration, the heat generated in the light emitting element 52 is transmitted to the heat sink 62 through the thermal pad 64 and the heat dissipation path 57. Thus, since the insulating layer is not interposed in the heat transfer path, the heat dissipation of the light emitting element can be improved as compared with the conventional structure.

  As shown in FIG. 2B, a plurality (here, two) of light emitting elements may be arranged on the aluminum substrate. These light-emitting elements are preferably configured so that they can be turned on and off individually. When a plurality of light emitting elements are mounted on one substrate in this way, the amount of heat generation increases, so there is a method for improving the heat dissipation performance by directly contacting the heat dissipation path, the light emitting element, and the heat sink as in this embodiment. Especially suitable.

  FIG. 3 shows an example in which the aluminum substrate 50 on which the light emitting element 52 shown in FIG. 2 is surface-mounted is used as a light source of the vehicular lamp 80.

  The vehicular lamp 80 has a lamp chamber 81 formed by a lamp body 87 having an opening on the front side of the vehicle (left side in FIG. 3) and an outer cover 89 made of a transparent resin that covers the opening of the lamp body 87. Have. A support base 84 is provided in the lamp chamber 81. The aluminum substrate 50 on which the light emitting element 52 is surface-mounted is mounted on the support base 84 and is erected in a substantially vertical direction in the lamp chamber. A projection lens 70 is disposed on the front side of the vehicle of the light emitting element 52. Above and below the projection lens 70, extension members 82 and 83 for hiding the structure inside the lamp chamber are installed.

  An aiming screw 86 is attached between the support base 84 and the wall surface of the lamp body 87 on the vehicle rear side, and the optical axis can be adjusted by changing the screwing amount of the aiming screw 86.

  A dotted line in FIG. 3 is a line connecting the outer edge of the light emitting region of the light emitting element 52 and the outer edge of the light incident region of the lens 70. As can be seen, it is desirable that the heat sink 62 is disposed on the substrate 50 so as not to block the light emitted from the light emitting element 52. Thereby, a light emitting element and a heat sink can be arrange | positioned on the same side of a board | substrate, without sacrificing light quantity.

  FIG. 4 shows another example in which the aluminum substrate 50 ′ on which the light emitting element 52 is surface-mounted is used as the light source of the vehicular lamp 80. Unlike the example shown in FIG. 3, here, the outer shape of the heat sink 68 protrudes inward from the line connecting the upper outer edge of the light emitting region of the light emitting element 52 and the upper outer edge of the light incident region of the lens 70. Yes. However, by configuring the light emitting element side surface 68a of the heat sink 68 as a reflective surface, light distribution control using this reflective surface can be performed.

  As shown in FIG. 4, when performing light distribution control using the reflective surface of the heat sink 68, it is preferable to stand the aluminum substrate 50 ′ so that the heat sink 68 is positioned above the light emitting element 52 in the lamp chamber. This will be described with reference to FIG.

  Consider a vehicular lamp in which a plurality of light emitting elements 52 are arranged in the horizontal direction and can be turned on and off individually. If the aluminum substrate 50 ′ is erected so that the heat sink 68 is positioned below the light emitting element 52, the upper side of the horizontal line H spreads horizontally by the individual light emitting elements as shown in FIG. The light distribution patterns (R2 to R4, L2 to L4) are formed. In the case where a well-known ADB (Adaptive Driving Beam) for forming a light-shielding region so as not to give glare to the preceding vehicle C using this vehicular lamp is used, it is arranged close to the left and right of the preceding vehicle C as shown in the figure. When the light is formed, the light distribution above the horizontal line H is widened, so that it becomes impossible to sufficiently irradiate the road surface below the preceding vehicle C that needs to improve visibility.

  On the other hand, when the aluminum substrate 50 ′ is erected so that the heat sink 68 is positioned above the light emitting element 52 (that is, in the example shown in FIG. 4), as shown in FIG. Light distribution patterns (R1 to R4, L1 to L4) in which the lower side of the horizontal line H spreads in the horizontal direction are formed by the elements. When ADB is performed using this vehicular lamp, light distribution close to the left and right of the preceding vehicle C can be realized, and the light distribution below the horizontal line H is widened. The road surface can also be illuminated.

  In the above description, the aluminum substrate has been described as an example. However, the present invention can be applied to any printed board other than an aluminum substrate such as a glass epoxy substrate. The substrate itself may be made of an insulating material, or may be an insulating layer formed on the surface of the conductor substrate as described above.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. The configuration shown in each figure is for explaining an example, and any configuration that can achieve the same function can be changed as appropriate, and the same effect can be obtained.

  Further, the above-described embodiments can be used in combination as long as they do not contradict each other.

  Instead of the heat sink, a cooling fan or a Peltier element may be arranged.

  50 aluminum substrate, 52 light emitting element, 54 insulating layer, 56 conductor layer, 57 heat dissipation path, 58 insulating layer, 60 metal base, 62 heat sink, 64 thermal pad, 68 heat sink, 68a reflecting surface, 70 lens.

Claims (5)

An insulating substrate;
A circuit pattern on the insulating substrate;
A light emitting element electrically connected to the circuit pattern;
With
A heat dissipation path that is in contact with the light emitting element and insulated from the circuit pattern is formed,
A printed circuit board further comprising a heat sink disposed so as to be in direct contact with the heat dissipation path.   The printed circuit board according to claim 1, wherein the heat sink is disposed so as not to block light emitted from the light emitting element.   The printed circuit board according to claim 1, wherein a part of the surface of the heat sink is configured as a reflection surface of light emitted from the light emitting element.   The printed circuit board according to any one of claims 1 to 3, further comprising a plurality of the light emitting elements configured to be individually lit and extinguished.   5. A vehicle lamp in which the printed circuit board according to claim 1 is erected in a substantially vertical direction in a lamp chamber, wherein the heat sink is disposed above the light emitting element. Lamps.

Images