JP2008078584A - Light-emitting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting apparatus capable of positively ensuring a heat transfer action to a heat radiating plate without allowing bubbles to remain when the heat radiating plate is integrally joined to the bottom surface of a surface-mounting type light-emitting diode via binder. <P>SOLUTION: The apparatus is provided with the surface-mounting type light-emitting diode 1 having a light-emitting diode chip 12 provided in a package 11, a wiring substrate 2 having the light-emitting diode 1 mounted thereon, and the heat radiating plate 3 integrally joined to the back surface of the wiring substrate 2. A convex portion 31 is formed on the surface of the wiring substrate 2 side of the heat radiating plate 3, and an insertion hole 23 having a diameter larger than that of the outside shape of the convex portion 31 is formed on the wiring substrate 2. The convex portion 31 is integrally joined via a solder 6 to the bottom surface of the package 11 through the insertion hole 23. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light-emitting device using a surface-mounted light-emitting diode as a light source.

As a conventional light-emitting device, a surface-mounted light-emitting diode in which a light-emitting diode chip is mounted on the bottom of a mortar-shaped recess formed in a package has been proposed (see, for example, Patent Documents 1 and 2).
JP 2003-152228 A JP 2006-13324 A

  By the way, since the surface mount type light emitting diode as described above deteriorates characteristics such as light emission efficiency due to a temperature rise due to heat generation of the light emitting diode chip itself, it is preferable to perform cooling so as to suppress the temperature rise. In order to cool the light emitting diodes, for example, it is conceivable to increase the cooling efficiency by integrally bonding a heat sink to the bottom surface of the package using a binder such as soldering or adhesive.

  However, when the heat sink is simply bonded to the bottom surface of the package of the light emitting diode using a binder, air bubbles are likely to be interposed between the bottom surface of the package and the heat sink. When the binder is solidified with air bubbles intervening, it becomes difficult to efficiently conduct the heat of the light emitting diodes to the heat sink due to the heat insulating action of the bubbles, and cooling efficiency is lowered even if a heat sink is provided. End up.

  The present invention has been made to solve the above-described problems. When the heat sink is integrally joined to the bottom surface of the surface-mount type light emitting diode by a binder, there is no air bubble, and the heat sink. It is an object of the present invention to provide a light-emitting device that can reliably ensure a heat conduction action.

  In order to achieve the above object, in the light emitting device of the present invention according to claim 1, a surface mount type light emitting diode in which a light emitting diode chip is provided in a package, and the light emitting diode are mounted. A wiring board, and a heat sink integrally joined to the back surface of the wiring board, and a convex portion is formed on the surface of the heat sink on the wiring board side, while the convex portion is formed on the wiring board. An insertion hole having a larger diameter than that of the outer shape is formed, and the convex portion is integrally bonded to the bottom surface of the package through the insertion hole via a binder such as solder or adhesive.

  According to a second aspect of the present invention, there is provided a semiconductor device according to the first aspect, wherein the projection is joined to the package in a circular arc shape.

  According to the present invention, the protrusion provided on the heat sink is joined to the bottom surface of the light emitting diode package through the insertion hole of the wiring board having a larger diameter than the outer shape of the protrusion. A gap is formed between For this reason, when the heat sink is integrally bonded to the bottom surface of the light emitting diode package with a binder such as solder or adhesive, the air bubbles easily escape to the outside due to the presence of the convex portion and the gap around the convex portion. Is less likely to be trapped inside the solidified binder. For this reason, the heat conduction action from the light emitting diode to the heat sink can be ensured reliably.

  In particular, when the joint surface with the package of the convex portion is formed in an arc shape, the binder is solidified from the center of the convex portion, so that the bubbles are more easily driven out toward the gap around the convex portion. For this reason, the heat conduction effect from the light emitting diode to the heat sink can be ensured more reliably.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a light-emitting device according to an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view showing a main part of FIG. The light-emitting device of this embodiment includes a surface-mounted light-emitting diode 1, a wiring board 2 on which the light-emitting diode 1 is mounted, and a heat sink 3 integrally joined to the back surface of the wiring board 2. ing.

  The light emitting diode 1 has a package 11 made of ceramic such as alumina, and a mortar-shaped recess 11a is formed in the center of the package 11, and a light emitting diode chip is formed on the flat bottom of the recess 11a. 12 is flip-chip mounted and electrically connected to the pair of leads 13a and 13b. In addition, a reflective film 14 formed by, for example, glossy silver plating is formed in the recess 11a so as to cover the inner peripheral surface thereof. Further, each of the leads 13a and 13b passes through the package 11 and is drawn to the outside.

  The wiring board 2 has wiring patterns 22a and 22b formed on an insulating substrate 21 such as ceramic, and the leads 13a and 13b are electrically connected to the wiring patterns 22a and 22b via solders 5a and 5b. It is connected. An insertion hole 23 is formed in a portion of the wiring board 2 corresponding to the substantially central position of the bottom of the package 11 of the light emitting diode 1.

  The heat radiating plate 3 is made of a metal having good thermal conductivity such as Al and Cu, and a convex portion 31 is formed on the surface of the wiring board 2 side. And this convex part 31 is integrally joined by the solder 6 to the bottom face of the package 11 of the light emitting diode 1 through the insertion hole 23 of the wiring board 2. In this case, the diameter of the insertion hole 23 of the wiring board 2 is formed larger than the outer shape of the convex portion 31 of the heat radiating plate 3, so that a gap 7 is formed between the outer periphery of the convex portion 31 and the insertion hole 23. ing.

  When the light emitting diode 1 is mounted on the wiring board 2, the cream-like solder 6 is applied to the convex portion 31 of the heat radiating plate 3. Similarly, cream-like solders 5a and 5b are applied to the outside of the package 11 of the light emitting diode 1 as well. Then, the light emitting diode 1 is placed on the wiring board 2 and the solders 5a, 5b, 6 are reflowed. Thereby, the light emitting diode chip 12 is electrically connected to the wiring patterns 22a and 22b of the wiring board 2 via the leads 13a and 13b and the solders 5a and 5b.

  Moreover, when the solder reflow process is performed, bubbles are included in the solder 6 due to the presence of the convex portion 31 provided in the heat radiating plate 3 and the gap 7 between the insertion hole 23 secured around the convex portion 31. However, it is easy to escape to the outside, and the possibility that bubbles are trapped inside the solidified solder 6 is reduced.

  In particular, as in this embodiment, when the joint surface of the convex portion 31 with the package 11 is formed in an arc shape, the distance between the bottom surface of the package 11 of the light emitting diode 1 and the convex portion 31 is the center. Since the distance t1 on the side is shorter than the distance t2 on the outer side (t1 <t2), the solder 6 is preferentially solidified from the center of the convex portion 31. For this reason, the bubbles are easily driven out toward the gap 7 around the convex portion 31, and the possibility that the bubbles remain is further reduced. For this reason, the heat conduction action from the light emitting diode 1 to the heat sink 3 can be ensured reliably.

  In this embodiment, the case where the solder 6 is used as the binder for integrally joining the bottom surface of the package 11 of the light emitting diode 1 and the convex portion 31 of the heat radiating plate 3 has been described. The present invention can be applied even when an adhesive having good properties is used, and similar effects can be obtained.

It is sectional drawing which shows the light-emitting device in Embodiment 1 of this invention. It is sectional drawing which expands and shows the principal part of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting diode 11 Package 12 Light emitting diode chip 2 Wiring board 23 Insertion hole 3 Heat sink 31 Convex part 6 Solder (binder)
7 Clearance

Claims (2)

  A surface mount type light emitting diode in which a light emitting diode chip is provided in the package; a wiring board on which the light emitting diode is mounted; and a heat sink integrally joined to the back surface of the wiring board. A convex part is formed on the surface of the board on the side of the wiring board, while an insertion hole having a diameter larger than the outer shape of the convex part is formed in the wiring board, and the convex part passes through the insertion hole and the bottom surface of the package. A light emitting device characterized in that it is integrally bonded to the substrate through a binder such as solder or adhesive.   The light emitting device according to claim 1, wherein a joint surface of the convex portion with the package is formed in an arc shape.

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