JP2015018842A - Electrode pattern structure of light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode pattern structure of a light-emitting device, which prevents a short circuit due to solder without increasing cost or hindering miniaturization.SOLUTION: A light-emitting device includes a substrate 1, gold-plated electrode patterns 2 and 3 provided on the substrate 1, and a light-emitting element 4 mounted on the electrode patterns 2 and 3 with solder 7. The electrode patterns 2 and 3 have extension parts 2b and 3b extending in an outward direction of the substrate 1. Excess solder 7 melted during mounting of the light-emitting element 4 flows toward the corners of the substrate 1 by being guided by the extension parts 2b and 3b. As a result, a short circuit between the electrode patterns 2 and 3 and between element electrodes 5 and 6 due to the excess solder 7 can be prevented.

Description

  The present invention relates to a light-emitting device used for illumination, flash, and the like, and more particularly to a structure of an electrode pattern provided on a substrate for flip-chip mounting a light-emitting element on the substrate.

  In a conventional light emitting device of this type, when a light emitting element such as a light emitting diode is mounted on a substrate, the element electrode is mounted on an electrode pattern on the substrate using solder. Thus, in the light emitting device of the type in which the element electrode of the light emitting element is mounted on the electrode pattern on the substrate with solder, the solder provided on the electrode pattern for mounting not only wets the element electrode but also the remaining solder May flow out between adjacent electrode patterns, adjacent element electrodes, and the like, causing them to be short-circuited.

  Therefore, an attempt has been made to prevent a short circuit due to solder by applying a structure of a light emitting element in which a resist for blocking the flow of solder is provided on an electrode of a substrate (see, for example, Patent Document 1).

JP 2000-133845 A

  However, when the resist is formed on the electrode pattern as in the above prior art, there is a problem that the manufacturing process increases and the cost is increased. In addition, the conventional technique has a problem that a space for forming a resist has to be secured, which hinders downsizing.

  The problem to be solved by the present invention is to provide an electrode pattern structure of a light-emitting device that solves the above-mentioned problems of the prior art and prevents a short circuit due to solder without increasing costs or inhibiting downsizing. is there.

  The electrode pattern structure of the light emitting device of the present invention is a light emitting device comprising a substrate, an electrode pattern having a surface plated with gold, and a light emitting element mounted on the electrode pattern with solder. The electrode pattern has an extension extending in the outer direction of the substrate, and extra solder flows on the extension to induce solder.

  The electrode pattern in the electrode pattern structure of the light emitting device has a mounting portion on which the element electrode of the light emitting element is mounted by solder, and the extension portion is separated from the element electrode mounted on the mounting portion. It is extended | stretched from the said mounting part. Further, the substrate in the electrode pattern structure of the light emitting device has a rectangular planar shape, and the extension portion extends in the corner direction of the substrate. Further, the extension portion in the electrode pattern structure of the light emitting device is gold-plated thicker than the mounting portion.

  In the electrode pattern structure of the light emitting device of the present invention, an extension is provided in the electrode pattern on the substrate to guide the flow of solder in the direction of the extension, so that the solder flows between the electrode patterns and between the element electrodes. Can be prevented.

  Further, since the extension is formed when the electrode pattern is formed, it is possible to prevent a solder short without increasing the number of manufacturing steps.

  Furthermore, since the extension part of the electrode pattern is provided by being extended to a part that becomes a dead space, such as near a corner in the outer side direction of the substrate, it can be provided without hindering the downsizing.

  In addition, by thickening the gold plating of the extension part to improve the wettability and affinity of the solder and to facilitate the flow of solder in the direction of the extension part, it is possible to reliably induce excess solder in the direction of the extension part. Can do.

It is a perspective view which shows the electrode pattern structure of the light-emitting device which concerns on 1st Embodiment of this invention. It is a top view of the light-emitting device shown in FIG. It is a side view of the light-emitting device shown in FIG. It is a bottom view which shows the mounting surface of the light emitting element shown in FIG. It is an enlarged plan view of the extension part of the electrode pattern shown in FIG. It is an expanded sectional view of the extension part of the electrode pattern shown in FIG. It is a perspective view which shows the electrode pattern structure of the light-emitting device which concerns on 2nd Embodiment of this invention. It is a top view of the light-emitting device shown in FIG. It is a side view of the light-emitting device shown in FIG. It is an enlarged plan view of the extension part of the electrode pattern shown in FIG.

  1 to 5 show a light emitting device according to a first embodiment of the present invention. Here, reference numeral 1 denotes a substrate having a rectangular planar shape, and a pair of electrode patterns 2 and 3 are provided on the surface of the substrate 1. The electrode patterns 2 and 3 are formed by etching a copper foil previously provided on the surface of the substrate 1 and sequentially performing nickel plating and gold plating. Note that a surface mounting electrode (not shown) is provided on the bottom surface of the substrate 1 in the present embodiment, and is connected to the electrode patterns 2 and 3 by through holes or the like.

  Reference numeral 4 denotes a light-emitting element such as a light-emitting diode. As shown in FIG. 4, a pair of element electrodes 5 and 6 are provided on the surface on the mounting side.

  The electrode patterns 2 and 3 in the present embodiment include mounting portions 2a and 3a formed side by side near the approximate center of the surface of the substrate 1 so as to correspond to the element electrodes 5 and 6 of the light emitting element 4, respectively. Extension portions 2b and 3b extending from 2a and 3a to the outside of the substrate 1 are provided.

  The mounting portions 2a and 3a are formed to have a rectangular shape slightly larger than the element electrodes 5 and 6. Further, the extension portions 2b and 3b in the present embodiment have a rectangular shape in which the edge of the plane is parallel to the edge of the substrate 1, and the corner of the substrate 1 from the corner in the outer direction of the mounting portions 2a and 3a. It is provided to extend in the direction of the part.

  In the light emitting device having the above configuration, when the light emitting element 4 is mounted on the electrode patterns 2 and 3 of the substrate 1, as shown in FIG. 6, the solder 7 is previously placed on the mounting portions 2 a and 3 a of the electrode patterns 2 and 3. The solder is heated and melted by reflow or the like while the element electrodes 5 and 6 are pressed against the solder 7 and mounted. At the time of such mounting, the molten solder 7 wets the element electrodes 5 and 6 and the remaining solder 7 flows to the surroundings. The surplus solder 7 flows on the electrode pattern 2 made of a metal having high affinity with the solder 7, and in this embodiment, the solder 7 flows so as to spread on the extension portion 2b. As a result, the surplus solder 7 is guided to the extension portion 2b and flows toward the outside of the substrate 1 away from the mounting portion 2a, and flows between the element electrodes 5 and 6 and between the electrode patterns 2 and 3 to short-circuit them. Nothing will happen.

  7 to 10 show a light emitting device according to a second embodiment of the present invention. The light emitting device according to this embodiment is obtained by changing the shapes of the extended portions 2b and 3b of the electrode patterns 2 and 3 shown in the first embodiment, and is straight from the mounting portions 2a and 3a of the electrode patterns 2 and 3. Are extended in the direction of the corners of the substrate 1 to form extensions 2b and 3b. The vicinity of the corner of the substrate 1 is farthest from the device electrodes 5 and 6 on the surface of the substrate 1 on which the light emitting device 4 is mounted. Since the second embodiment has substantially the same configuration as that of the first embodiment except that the shapes of the extended portions 2b and 3b of the electrode patterns 2 and 3 are different, detailed description will be omitted by using the same reference numerals.

  Further, in the electrode patterns 2 and 3 shown in FIGS. 1 and 7, when the thickness of the gold plating of the extension portions 2b and 3b is made larger than the gold plating of the mounting portions 2a and 3a, the wettability of the solder 9 in the thick gold plating portion. As a result, the solder 9 is more likely to flow into the extensions 2b and 3b. Thereby, it is possible to make it easier to guide the excess solder 9 in the direction of the extensions 2b and 3b.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2,3 Electrode pattern 2a, 3a Mounting part 2b, 3b Extension part 4 Light emitting element 5,6 Element electrode 7 Solder

Claims (4)

A substrate,
An electrode pattern with a gold-plated surface provided on the substrate;
A light emitting element mounted on the electrode pattern by solder;
In a light emitting device comprising:
The electrode pattern structure of a light-emitting device, wherein the electrode pattern has an extension extending in an outer side direction of the substrate, and the solder is guided by flowing excess solder on the extension.   The electrode pattern includes a mounting portion on which the element electrode of the light emitting element is mounted by solder, and the extension portion is extended from the mounting portion so as to be separated from the element electrode mounted on the mounting portion. The electrode pattern structure of the light-emitting device according to claim 1.   The electrode pattern structure of the light emitting device according to claim 2, wherein the substrate has a rectangular planar shape, and the extension portion extends in a direction of a corner of the substrate.   The electrode pattern structure of the light-emitting device according to claim 1, wherein the extension portion is gold-plated thicker than the mounting portion.

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