JP2013008772A - Side-mounting led - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a side-mounting LED which can obtain a sufficient heat dissipation effect by increasing a surface electrically grounded to a motherboard and can also optimally regulate the range and amount of solder application at the time of packaging.SOLUTION: A side-mounting LED 11 comprises: a substrate 12 having a front face, a back face, and a peripheral face formed between the front face and the back face; front electrodes and back electrodes 16a and 16b respectively formed on the front face and the back face of the substrate 12; a light-emitting element arranged on the front face of the substrate 12; and through-holes 14a and 14b which are formed on part of the peripheral face of the substrate 12, and which bring the front electrodes into conduction with the back electrode 16a and 16b. The back electrode 16a and 16b are formed substantially in the entire range of the back face of the substrate 12. A resist pattern 20 is formed on the surfaces of the back electrode 16a and 16b. The resist pattern 20 exposes solder application surfaces 22a and 22b excluding part of the back electrodes 16a and 16b which surrounds the through-holes 14a and 14b.

Description

  The present invention relates to a side-mounted LED that includes a light emitting element on a front surface and is mounted on a mother board via a side surface.

  Conventionally, a side-mounted LED as disclosed in Patent Documents 1 and 2 is used as a light source for irradiating light toward a side surface of an irradiation object such as a light guide plate. FIG. 5A is a rear view when a conventional general side-mounted LED 1 is mounted on the mother board 9, and FIG. 5B is a bottom view of the side-mounted LED 1. The side-mounted LED 1 includes a rectangular substrate 2 on which a lower surface 2b is placed on a mother board 9, a light emitting element 3 mounted on the front surface 2a of the substrate 2, and a front surface surrounding the light emitting element 3. A reflection frame 8 provided on the 2a side is provided.

  The substrate 2 is provided with a pair of through holes 4 at both ends of the lower side surface 2b placed on the mother board 9, and the pair of front electrodes 5 and the back surface 2c side on the front surface 2a side through the through holes 4. A pair of back electrodes 6 are formed so as to go around. On the other hand, a mounting electrode pattern (not shown) is provided on the mother board 9 at a position corresponding to the pair of through holes 4, and the pair of through holes 4 and the pair of back electrodes 6 are provided on the mounting electrode pattern. The substrate 2 is placed with the lower surface 2b facing down so as to correspond. Then, solder 7 is applied from the through hole 4 to the back electrode 6 to achieve electrical connection with the mother board 9.

JP 2000-196153 A JP 2003-234507 A

  As shown in FIG. 5, the side-mounted LED 1 appropriately sets the amount of solder 7 to be applied to the back surface 2c side of the substrate 2, so that the formation area of the back electrode 6 is limited. Thus, if the formation range of the back electrode 6 is widened without being restricted, when the solder 7 is applied more than necessary, the solder 7 becomes thicker so as to scoop up the back surface 2 c of the substrate 2. As a result, due to the shrinkage when the solder 7 is solidified, the substrate 2 may be pulled to the back surface 2 c side, and the front surface 2 a may be lifted from the motherboard 9. Therefore, the back electrode 6 formed on the back surface 2c of the substrate 2 is limited to the peripheral portion of the through hole 4, or the amount of solder 7 applied is adjusted according to the shape and size of the substrate 2, etc. Measures have been taken.

  However, if the formation range of the back electrode 6 on the substrate 2 is limited to be narrow, the electrical connection with the mounting electrode pattern formed on the mother board 9 becomes insufficient, and the electrical characteristics may deteriorate. Further, since the back electrode 6 also has a heat dissipation property, there is a possibility that a sufficient heat dissipation effect cannot be obtained if the grounding surface with the mother board 9 is reduced. Therefore, regarding the heat dissipation, it is desirable to set the back electrode 6 formed on the substrate 2 as wide as possible. However, in order to limit the application range and application amount of the solder 7, the formation range of the back electrode 6 is widened. Could not set.

  Accordingly, an object of the present invention is to provide a sufficient heat dissipation effect by increasing the electrical ground plane with the mother board, and to be able to optimally regulate the solder coating range and coating amount when mounting. It is to provide a mountable LED.

  In order to solve the above problems, a side-mounted LED according to the present invention includes a front surface, a back surface, a substrate having a peripheral surface formed between the front surface and the back surface, and front electrodes formed on the front surface and the back surface of the substrate, respectively. A side-mount type LED comprising: a back electrode; a light emitting element disposed on a front surface of the substrate; and a through hole formed in a part of a peripheral surface of the substrate and electrically connecting the front electrode and the back electrode. The back electrode is formed on substantially the entire back surface of the substrate, a resist pattern is formed on the surface of the back electrode, and the resist pattern is formed except for a part of the back electrode surrounding the through hole, The partial back electrode is exposed.

  According to the side-mounted LED according to the present invention, since the back electrode is formed in substantially the entire area on the back side of the substrate, a sufficient grounding surface with the mother board can be secured, and good electrical conductivity with low electrical resistance. Can be obtained. In addition, the resist pattern covering the back electrode exposes the connection region by the solder centering on the through-hole, so that the substrate on which the light emitting element is mounted does not tilt, and the motherboard is in a stable state. It can be mounted on top.

  Further, by forming the resist pattern in a line shape except for a part of the back electrode surrounding the through hole, a portion where the back electrode is directly exposed can be widened. This enhances the heat dissipation effect on the back side of the substrate.

  Further, by adjusting the formation range of the resist pattern, it is possible to prevent the excessive solder from creeping up according to the size of the substrate and the mounting range with the mother board. Accordingly, it is possible to conduct and fix in a stable state so that the front side on which the light emitting element is mounted does not float from the motherboard.

It is the perspective view which looked at the side mounted LED of 1st Embodiment from the back side. It is the perspective view which looked at the said side mounted LED from the front side. It is the rear view (a) and bottom view (b) of the said side mount type LED. It is a rear view of side mounted LED of 2nd Embodiment. It is the rear view (a) and bottom view (b) of the conventional side mounted LED.

  Hereinafter, embodiments of a side-mounted LED according to the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show a side-mounted LED 11 according to a first embodiment of the present invention. The side-mounted LED 11 includes a substantially rectangular parallelepiped substrate 12, a light emitting element 13 mounted on the front surface 12a of the substrate 12, and a reflection frame 18 mounted on the front surface 12a side so as to surround the light emitting element 13. It is configured.

  The substrate 12 is formed of an insulating material such as a general epoxy resin or BT resin, and includes a cathode and an anode for connecting the light emitting elements 13 to both ends of the front surface 12a as shown in FIG. 3B. A pair of front electrodes 15a and 15b are provided, and a pair of through holes 14a and 14b that are electrically connected to the front electrodes 15a and 15b are provided on the lower side surface 12b that is one of the peripheral surfaces. The through holes 14 a and 14 b are formed by cutting out the corners of the lower side surface 12 b in an arc shape, and are formed along the thickness direction of the substrate 12. A pair of back electrodes 16a and 16b that are electrically connected to the through holes 14a and 14b are formed on the back surface 12c of the substrate 12. The pair of back electrodes 16a and 16b are formed on the entire back surface 12c so as to face each other with an insulating region 21 where a part of the substrate 12 is exposed.

  The pair of back electrodes 16a and 16b can increase heat dissipation by widening the cross-sectional area exposed on the lower side surface 12b of the substrate 12 and increasing the number of portions that are in contact with the mother board 19. For this reason, in the present embodiment, the pair of back electrodes 16a and 16b are formed so that the insulating region 21 extends in a direction orthogonal to the mother board 19 and the right and left direction separating the insulating region 21 is divided into two. The pair of back electrodes 16a and 16b need not be symmetrically formed, and may be non-right and left depending on the shape of the mounting electrode pattern formed on the mother board 19. Thereby, a position where the insulating region 21 is provided is set. Solder coating surfaces 22 a and 22 b for joining to the mother board 19 and the solder 17 are set on the back electrodes 16 a and 16 b formed in this way. The solder coating surfaces 22a and 22b are obtained by exposing a part of the insulating resist pattern 20 covering the back surface 12c of the substrate 12, and a predetermined range of back electrodes 16a and 16b surrounding the through holes 14a and 14b. Is exposed in a square shape or an arc shape.

  As shown in FIG. 3A, the resist pattern 20 is a mounting electrode pattern (not shown) in which a lower surface 12b provided with a pair of through holes 14a and 14b of the substrate 12 is formed on a mother board 19. In this case, the solder 17 has a role of preventing excessive scooping of the solder 17. The resist pattern 20 is formed of a photoresist, a screen printing resist, an etching resist, a plating resist, a solder resist, or the like. The resist pattern 20 formed in this manner restricts the creeping of the solder 17, thereby suppressing the tensile stress on the back surface 12 c side of the substrate 12 due to the shrinkage when the solder 17 is solidified. This prevents the floating phenomenon on the front surface 12a side of the substrate 12 on which the light emitting element 13 is mounted.

  In order to effectively suppress such a floating phenomenon, as shown in FIG. 3A, the height position where the resist pattern 20 is provided is preferably at least half or less of the entire height of the substrate 12. In addition, as far as the width is concerned, it suffices if the size is such that the solder 17 does not get over the minimum.

  The light emitting element 13 mounted on the front surface 12a of the substrate 12 is a quadrangular laminated chip body composed of a P layer and an N layer (not shown) having a pair of element electrodes on the upper surface, and the P layer and the N layer. The strongest light is emitted from the PN junction layer, which is the junction part. The irradiation range by the light emitted from this PN junction layer extends to the entire front surface 12 a centering on the light emitting element 13. After mounting the light emitting element 13, the pair of element electrodes and the pair of front electrodes 15a and 15b corresponding to each other are connected by bonding wires (not shown).

  As shown in FIG. 1, a reflection frame 18 for determining the irradiation direction of light emitted from the light emitting element 13 is mounted on the front surface 12 a side of the substrate 12. The reflective frame 18 is filled with a transparent or translucent resin material 23 made of epoxy or silicon for protecting the light emitting element 13. The resin material 23 is dispersed with yttrium, aluminum, garnet, which is a raw material of fluorescent particles, and a dye, which is a raw material of pigment particles, so that the light emitting element 13 is a blue light emitting element, thereby emitting light in multiple colors or intermediate colors. be able to.

  As shown in FIG. 3, the side-mounted LED 11 is placed at a predetermined position on the mother board 19 with the lower side face 12 b facing down so that the front face 12 a on which the light emitting element 13 is mounted is parallel to the mother board 19. Is done. At this time, the cross sections of the pair of through-holes 14a and 14b and the pair of back electrodes 16a and 16b exposed on the lower surface 12b side are bonded onto the solder 17 applied on the mounting electrode pattern (not shown) of the mother board 19. Then, the entire mother board 19 is reflow processed. By solidifying the solder 17 by this reflow process, the side-mounted LED 11 is fixed on the mother board 19 and an electrical connection is achieved.

  As shown in FIG. 3A, the side-mounted LED 11 mounted and arranged in this way has the entire lower section of the pair of back electrodes 16a and 16b closely adhered to the mounting pattern on the mother board 19 in a wide range. Therefore, the heat generated from the pair of back electrodes 16a and 16b can be effectively released to the mother board 19. Further, since the pair of back electrodes 16a and 16b whose surfaces are covered with the resist pattern 20 are formed on substantially the entire back surface 12c of the substrate 12, the light emitting element 13 emits light from the back surface 12c side of the substrate 12 as well. The heat generated by the can be effectively released to the outside.

  Further, due to the shrinkage when the solder 17 is solidified by the reflow process, a force that pulls the substrate 12 toward the back surface 12c side where the solder 17 is piled up acts. However, the mother board 19 in the back electrodes 16a and 16b. Since the solder application surfaces 22a and 22b, which are the bonding surfaces, are limited to a certain range by the resist pattern 20, the solder 17 is prevented from creeping up. As a result, the substrate 12, in particular, the front surface 12 a side on which the light emitting element 13 is mounted can be prevented from being lifted from the motherboard 19, and light is emitted straight toward the side surface of the light guide plate without shifting the light emitting direction. be able to.

  FIG. 4 shows the back structure of the side-mounted LED 31 of the second embodiment. In the side-mounted LED 11 of the first embodiment, the entire back surface 12c of the substrate 12 excluding the solder coating surfaces 22a and 22b is covered with the resist pattern 20, but the resist pattern 32 in the side-mounted LED 31 of the second embodiment is used. Is formed in a line shape so as to surround the solder application surfaces 22a and 22b. As a result, the solder application area is restricted, and the back electrodes 16a and 16b not covered with the resist pattern are widely exposed, so that the heat radiation action is further enhanced. The resist pattern 32 may have a minimum width that prevents the solder from protruding from the solder application surfaces 22a and 22b. In addition, since the back electrodes 16a and 16b are common to the first embodiment, a sufficient heat radiation effect on the grounding surface with the mother board 19 can be obtained.

  As described above, the side-mounted LED of the present invention has a wide grounding surface of the back electrode with respect to the motherboard to be mounted, and therefore can efficiently release heat during light emission to the motherboard and the outside air. it can. Also, by masking the back electrode with a resist pattern, it is possible to limit the area for applying solder, so that it can be mounted on the motherboard in a stable state without causing bonding failure or substrate tilt. it can.

11 Side-mounted LED
DESCRIPTION OF SYMBOLS 12 Board | substrate 12a Front surface 12b Lower side surface 12c Back surface 13 Light emitting element 14a, 14b Through-hole 15a, 15b Front surface electrode 16a, 16b Rear surface electrode 17 Solder 18 Reflecting frame 19 Motherboard 20 Resist pattern 21 Insulating region 22a, 22b Solder coating surface 23 Side mounted LED
32 resist pattern

Claims (5)

A substrate having a front surface, a back surface and a peripheral surface formed between the front surface and the back surface;
Front and back electrodes formed on the front and back surfaces of the substrate, respectively;
A light emitting device disposed on the front surface of the substrate;
A side-mounted LED that is formed on a part of the peripheral surface of the substrate and includes a through hole that conducts the front electrode and the back electrode,
The back electrode is formed on substantially the entire back surface of the substrate, a resist pattern is formed on the surface of the back electrode, and the resist pattern is formed except for a part of the back electrode surrounding the through hole. A side-mounted LED, wherein the partial back electrode is exposed.   The side-mounted LED according to claim 1, wherein the resist pattern is formed on the back electrode and the back surface of the substrate exposed from the back electrode.   2. The side-mounted LED according to claim 1, wherein the resist pattern is formed on substantially the entire surface of the back electrode except for a part of the back electrode surrounding the through hole.   2. The side-mounted LED according to claim 1, wherein the resist pattern is formed in a line shape on the back electrode except for a part of the back electrode surrounding the through hole. 2. The side-mounted LED according to claim 1, wherein solder for external connection is applied to the LED mounting on the surface of a part of the back electrode exposed from the resist pattern.

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