JP3357756B2 - Surface mount type light emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type light emitting device widely used for various AV equipment, telephones and other general electronic equipment.

[0002]

2. Description of the Related Art Light emitting diodes and photocouplers as shown in FIGS. 8 and 9 have been known as conventional surface mounted light emitting devices. The light emitting diode is a light emitting diode chip having a pair of electrode portions 4, 6 disposed opposite to the surface of a glass epoxy substrate 2, a die bond on one of the electrode portions 4, and a wire bond on the other electrode portion 6. 8 and
Light emitting diode chip 8 for wire protection etc.
And a sealing resin 10 formed by potting or transfer molding of a liquid epoxy resin covering the periphery thereof,
Was composed of The photocoupler includes a substrate 12 made of a heat-resistant resin, a plurality of lead frames 14 insert-molded in the substrate 12, an infrared light emitting diode 16 die-bonded and wire-bonded to a predetermined position of the lead frame 14, and The light-receiving element 18 is composed of a phototransistor or a photodiode, and a sealing resin 20 that is transfer-molded so as to cover them.

[0003]

As described above, in the surface mount type light emitting device, the light emitting diode chip 8 is usually used.
And the like. Since this compound semiconductor element is fragile, there is a danger of being broken due to weak mechanical stress, and bonding failure may occur at the time of wire bonding, or damage may be caused by stress stress when the sealing resin is cured. Further, when reflow soldering is performed at the time of mounting, the sealing resin 10 or 20 made of the moisture-absorbed epoxy resin expands due to heat and is subjected to stress stress and is damaged. there were.

Further, the conventional surface mount type light emitting device has a problem that expensive equipment such as a wire bonder and a transfer molding machine is required due to its structure.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to eliminate mechanical stress applied to a light emitting diode chip, prevent breakage of the light emitting diode chip, poor contact, etc., and improve product reliability. Another object of the present invention is to provide a surface-mounted light-emitting device that can prevent a cost increase by reducing a manufacturing process that requires expensive equipment.

[0006]

According to the present invention, there is provided a surface mount type light emitting device comprising: a light transmitting substrate having a concave portion provided on a surface thereof; a light transmitting substrate formed on a surface of the substrate and provided on a bottom portion of the concave portion. A first electrode portion having a connection portion, a second electrode portion formed on the front surface of the substrate, and an electrode connection portion provided on each of the front and back surfaces, and one of the electrode connection portions is a connection portion of the first electrode portion. A light emitting diode chip fixed to the bottom of the concave portion so as to contact the flexible substrate; a flexible substrate having flexibility and being fixed to the surface of the substrate so as to cover an opening of the concave portion; A third electrode portion provided on the surface facing the substrate and provided with a connection portion that contacts the other electrode connection portion of the light emitting diode chip and also contacts the second electrode portion. is there.

[0007]

In the surface mount type light emitting device of the present invention, the first electrode portion provided on the substrate and the third electrode portion provided on the flexible substrate are respectively connected to the connection portions which are in contact with the electrode portions of the light emitting diode chip. Is provided. When the light emitting diode chip is fixed to the bottom of the concave portion of the substrate, one of the electrode connecting portions of the light emitting diode chip and the connecting portion of the first electrode portion are in contact with each other, and when the flexible substrate is fixed so as to cover the opening of the concave portion. The other electrode connecting portion of the light emitting diode chip contacts the third electrode portion, and at this time, the second electrode portion contacts the third electrode portion. As a result, one electrode connection of the light emitting diode chip is connected to the first electrode, and the other electrode connection is connected to the second electrode via the third electrode. Then, by mounting the surface mounted light emitting element having such a configuration on the motherboard with the flexible substrate side facing the motherboard side, the light emitting diode chip is housed in the concave portion of the substrate and protected, and at the same time, the light emitting diode chip is mounted on the motherboard. It is protected from heat and the like by an air layer formed between the motherboard.

[0008]

FIG. 1 is a sectional view showing a surface mount type light emitting device according to one embodiment of the present invention. Reference numeral 22 denotes a substrate made of light-transmittable glass epoxy, glass, or the like that can be plated with metal. As shown in FIG. 2, the substrate 22 has a relatively thin rectangular parallelepiped shape, and has a circular or elliptical concave portion 24 at the center of its surface. The recess 24 has a bottom 24b having a smaller diameter than the opening 24a,
A circumferential inner side surface 24c that is inclined from the opening 24a toward the bottom 24b is provided.

[0009] The substrates 26 and 28 are formed by plating, printing or the like.
2 are first and second electrode portions formed on the surface of the second electrode. The first and second electrode portions 26 and 28 in the present embodiment correspond to the substrate 2
2 are formed so as to face each other across the recess 24 from the front surface 22a to the side surface 22b and the back surface 22c. The first electrode portion 26 has a connection portion 26a extending from the surface 22a of the substrate 22 to the bottom portion 24b through the inner side surface 24c of the concave portion 24. The end of the connection portion 26a is formed in a shape in which the ring is substantially halved so as to match the position of the electrode connection portion of the light emitting diode chip described later.

Reference numeral 30 denotes a light emitting diode chip, which is shown in FIG.
As shown in FIGS. 4A and 4B, the anode 30a, the cathode 30b, and the substrate 30c are stacked in this order from the front side. An electrode connection portion 30d is provided at the center of the anode 30a, and electrode connection portions 30e are provided at two diagonal corners of the substrate 30c. The light emitting diode chip 30 has a bottom portion 2 of the recess 24 such that the electrode connection portion 30e contacts the connection portion 26a of the first electrode portion 26.
4b is fixed by silver paste or high-temperature solder.

Reference numeral 32 denotes a flexible substrate which is flexible and can be plated with metal.
4 so as to cover the opening 24a. On the surface of the flexible substrate 32 on the side facing the substrate 22, the fourth and third electrode portions 36, which are fixed to and connected to the first and second electrode portions 26 and 28 by silver paste or high-temperature solder, respectively, Reference numeral 34 is formed by plating, printing, or the like. The third electrode portion 34 is provided with a connection portion 34a that is extended to substantially the center of the flexible substrate 32. The connecting portion 34a is connected to the flexible substrate 32
Is fixed to the electrode connecting portion 30d of the light emitting diode chip 30 by silver paste or high-temperature solder when the substrate is fixed to the substrate 22. In addition, the fourth electrode portion 36 is a flexible substrate 3
2 when adhering to the substrate,
It is formed to improve the fixing property.

In the surface-mounted light emitting device of the present embodiment having the above-described structure, the surface of the light emitting diode chip 30 fixed on the bottom 24b of the concave portion 24 is positioned lower than the surface 22a of the substrate 22. Is set to
The thickness of the substrate 22 is set to 1 mm to several mm, and the thickness of the flexible substrate 32 is set to 50 to 100 μm.
m. Therefore, the connecting portion 34a of the third electrode portion 34 is connected to the electrode connecting portion 30 of the light emitting diode chip 30.
When fixed to d, the flexible substrate 32 bends inward of the recess 24 as shown in FIG.

As shown in FIG. 6, when the surface mount type light emitting device is mounted on a motherboard 38 by reflow soldering, the flexible substrate 32 is mounted on the motherboard 38.
To be in contact with the surface of At this time, since the center of the flexible substrate 32 is bent inwardly of the concave portion 24 of the substrate 22, there is a gap between the flexible substrate 32 and the motherboard 38, and the air that enters the flexible substrate 32 generates air. Layer 40 is formed. The air layer 40 formed in this manner serves to protect the light emitting diode chip 30 from mechanical stress stress and thermal stress received when reflow soldering the surface mounted light emitting device.

The surface mounted light emitting device mounted as described above emits light emitted from the light emitting diode chip 30 to the substrate 22.
To the outside via Therefore, the entire substrate 22 becomes bright, and the substrate 22 plays a role of condensing and diffusing light.

A light diffusing agent may be mixed in the substrate 22 made of glass epoxy, glass or the like. Further, at the time of manufacturing, an aggregate substrate in which many substrates 22 are aggregated may be used.

Further, the entire surface of the light emitting diode chip 30 may be coated with a transparent epoxy resin or a transparent silicon resin to increase the amount of light.

Further, in the present embodiment, the connecting portion 26a of the first electrode portion 26 extends from the surface 22a of the concave portion 24 to the inner surface 24a.
c, and is formed on the bottom portion 24b. As shown in FIG. 7, the through-hole electrode portion 26b is formed from the portion of the first electrode portion 26 which extends around the back surface 22c of the substrate 22. It can also be formed so as to be electrically connected to the connecting portion 26a formed on the bottom 24b of the concave portion 24 through the intermediary.

The shape of the concave portion 24 provided in the substrate 22 may be such that the inner side surface 24c is perpendicular to the bottom surface 24b, as shown in FIG. The shape of the opening 24a and the bottom 24b may be rectangular.

[0019]

According to the surface mounted light emitting device of the present invention,
Since the third electrode portion is fixed to the light emitting diode chip by utilizing the flexibility of the flexible substrate, it is possible to reduce a wire bonding step, a potting or transfer molding of a liquid epoxy resin, and the like. Therefore, wire bond failures, breakage of the light emitting diode chips, and the like that occur in these reduced processes are eliminated, and the reliability can be improved.

In addition, since a part of the manufacturing process is reduced and it is not necessary to use an expensive machine, the manufacturing cost can be greatly reduced.

Furthermore, the light emitting diode chip can be protected from thermal stress and the like at the time of reflow soldering by the air layer generated by the bending of the flexible substrate, and the reliability can be further improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a surface-mounted light emitting device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the appearance of the substrate shown in FIG.

FIG. 3 is a perspective view showing the appearance of the front side of the light emitting diode chip shown in FIG. 1;

FIG. 4 is a perspective view showing the appearance of the back side of the light emitting diode chip shown in FIG. 1;

FIG. 5 is a perspective view showing an appearance of the flexible substrate shown in FIG.

FIG. 6 is a cross-sectional view showing a state where the surface mount light emitting device shown in FIG. 1 is mounted.

FIG. 7 is a cross-sectional view showing a part of a first electrode part and a partly modified example of a substrate.

FIG. 8 is a perspective view showing a structure of a conventional light emitting diode.

FIG. 9 is a perspective view showing the structure of a conventional photocoupler.

[Explanation of symbols]

 22 substrate 24 concave portion 26 first electrode portion 28 second electrode portion 30 light emitting diode chip 32 flexible substrate 34 third electrode portion

Claims (1)

(57) [Claims] A light-transmitting substrate provided with a concave portion on a surface thereof; a first electrode portion formed on a surface of the substrate and having a connecting portion provided at a bottom portion of the concave portion; A second electrode portion formed on the front surface and an electrode connection portion provided on each of the front and back surfaces, and one of the electrode connection portions is fixed to the bottom of the concave portion so as to contact the connection portion of the first electrode portion. A diode chip, a flexible substrate having flexibility and fixed to the surface of the substrate so as to cover the opening of the concave portion; and a light-emitting device provided on a surface of the flexible substrate facing the substrate, A surface-mounted light emitting device, comprising: a third electrode portion provided with a connection portion that contacts the other electrode connection portion of the diode chip and also contacts the second electrode portion.