JPH08298345A - Chip type light emitting diode - Google Patents

Abstract

(57) [Abstract] [Purpose] To achieve the thinning of a chip type light emitting diode while having the mechanical and thermal reliability required for the chip type light emitting diode. [Structure] A pair of electrodes 23, 24 is formed on an upper surface of an insulating substrate 22.
Is provided, the light emitting diode element 27 is mounted on the surface side of the one electrode 23, and the light emitting diode element 27 and the surface side of the other electrode 24 are wire-bonded with a thin metal wire 28. Fine metal wire 28
While the transparent resin 29 is used to seal the pair of electrodes 2
Part of the back surface side of each of the electrodes 3 and 24 is exposed from the insulating substrate 22, and the exposed surface of the external connection terminal 2 of the electrodes 23 and 24.
By setting the number to 5, 26, the thickness can be reduced as compared with the conventional chip type light emitting diode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin chip type light emitting diode mounted on a small electronic device such as a mobile phone or a pager.

[0002]

2. Description of the Related Art Generally, a chip type light emitting diode of this type is provided with a pair of electrodes on the upper surface of a small insulating substrate, and a light emitting diode element is mounted on the surface side of one of the electrodes. After wire-bonding the surface side of the other electrode with a metal thin wire, while sealing the light emitting diode element and the metal thin wire with a transparent resin,
It has a structure in which external connection terminals of the pair of electrodes are provided on the lower surface side of the insulating substrate.

By the way, the external connection terminals provided on the pair of electrodes are conventionally of the type shown in FIGS. 16 and 17, for example (actual flat type 6-60.
157) and a type as shown in FIG. 18 (see Japanese Patent Laid-Open No. 6-61529).

The former chip type light emitting diode 1 shown in FIGS. 16 and 17 has a pair of electrodes 3 and 4 formed on the upper surface of an insulating substrate 2 and external connection terminals formed on the lower surface of the insulating substrate 2. Reference numerals 5 and 6 are formed in a U shape so as to wrap around the side surface of the insulating substrate 2 and are plated and wired. Then, the light emitting diode element 7 is mounted on the one electrode 3 and the other electrode 4
A thin metal wire 8 is wire-bonded to the upper surface of the electrode 3, and a transparent resin 9 is sealed on the electrodes 3 and 4 so as to cover the light emitting diode element 7 and the thin metal wire 8. On the other hand, the external connection terminals 5 and 6 formed by wrapping the electrodes 3 and 4 around the side surface of the insulating substrate 2 are connected to a conductor pattern of a printed circuit board (not shown) by soldering or the like.

The latter chip type light emitting diode 10 shown in FIG. 18 includes a pair of conductive resin bodies 11 and 12.
A pair of conductive resin bodies 11 and 12 is formed by integrally molding with the insulating resin body 13 interposed therebetween (two-color molding).
On the upper surface and the lower surface of the metal film 14, 15, 1 respectively.
6 and 17, and a light emitting diode element 18 and a bonding wire 19 are formed on the metal films 14 and 15 on the upper surface side.
The upper surface is sealed with a translucent resin 20, and the metal films 16 and 17 on the lower surface side are configured as external connection terminals.

[0006]

However, in each of the above-mentioned conventional chip type light emitting diodes, the insulating substrate or the conductive resin body is sandwiched between the electrodes, and the electrodes are provided on the upper surface and the external connection terminals are provided on the lower surface. Due to the three-layer structure, there is a limit to the reduction of the thickness of the light emitting diode. That is, in order to reduce the thickness of the light emitting diode, it is necessary to reduce the thickness of each of the insulating substrate, the electrodes on the upper surface, and the external connection terminals on the lower surface. However, since the mechanical and thermal reliability of the light emitting diode decreases as the thickness of each of the above is reduced, there is a structural limit when thinning is inevitable, and the expected thinning cannot be achieved. Because it could not be realized.

Further, the former chip type light emitting diode 1 described above must have a double-sided wiring substrate structure in which the electrodes 3 and 4 and the external connection terminals 5 and 6 are formed on the upper and lower surfaces of the insulating substrate 2. Therefore, the substrate itself becomes expensive because of the necessity of the plating process using the through holes, and as a result, it has been a hindrance to the cost reduction of the chip type light emitting diode.

On the other hand, the latter chip type light emitting diode 10
In that case, the conductive resin bodies 11 and 12 and the insulating resin body 13
Since the and are molded in two colors, the manufacturing cost of the mold is increased and the number of work steps is also increased, which has been an obstacle to lowering the price of the chip type light emitting diode as in the previous case.

[0009] Therefore, an object of the present invention is to provide a chip type light emitting diode which has a mechanical and thermal reliability required as a chip type light emitting diode, achieves a thin structure, and is inexpensive. .

[0010]

In order to solve the above-mentioned problems, a chip type light emitting diode according to the present invention is provided with a pair of electrodes on the upper surface of an insulating substrate, and a light emitting diode element is mounted on the surface side of one of the electrodes. Then, the light emitting diode element and the front surface side of the other electrode are wire-bonded with a thin metal wire, and the light emitting diode element and the thin metal wire are sealed with a light-transmissive resin, while the back surfaces of the pair of electrodes are formed. Part of the side is exposed from the insulating substrate, the exposed surface is a terminal for external connection of the electrode,

In addition, in order to expose the back surface side of the electrode, a notch or a hole is provided in the insulating substrate,

Further, the notch or hole provided in the insulating substrate is plated with metal to form a conductor,

The insulating substrate has a thickness of 20-50.
It is a polyimide film having a thickness of μm.

[0014]

According to the above-mentioned means, in the chip type light emitting diode of the present invention, a pair of electrodes is formed on the upper surface of the insulating substrate, and the back side of the electrodes is exposed from the insulating substrate to serve as a terminal for external connection. Since it has a layered structure and the back side of the electrodes is directly fixed to the printed circuit board, the light emitting diode is thinner than the conventional three-layered structure.

The cutouts and holes in the insulating substrate can be formed by removing a part of the insulating substrate by etching or laser processing.

Furthermore, by forming a conductor by metal-plating the notch or hole provided in the insulating substrate, the step between the external connection terminal and the lower surface of the insulating substrate is eliminated, and the conductor is flattened. The external connection terminals are brought into close contact with the bonding material such as solder applied to the solder, and the solder wettability at the time of bonding is further improved.

The insulating substrate has a thickness of 20 to 50 μm.
By using the polyimide film of m, it can be made extremely thin as compared with the conventional glass epoxy resin substrate without impairing the mechanical and thermal reliability, and when forming a cutout or a hole in the insulating substrate. Etching or laser processing becomes easy.

[0018]

Embodiments of the chip type light emitting diode according to the present invention will be described in detail below with reference to the accompanying drawings. 1 and 2 show a first embodiment of a chip type light emitting diode 21 according to the present invention. In this embodiment, the insulating film 22 as a substrate is composed of a polyimide film having a thickness of about 20 to 50 μm. This thickness is considerably thinner than the conventional general glass epoxy resin substrate, which is limited to a thinness of about 200 to 300 μm. Has sufficient strength and can be easily handled. A pair of electrodes 23, 24 made of a metal thin film such as a copper foil is formed on the upper surface side of the insulating film 22 formed of such a polyimide film, and both ends of the electrodes 23, 24 are the insulating film. The electrode 23, 24 is largely protruded from the insulating film 22, and a part of the back surface side of the electrode 23, 24 is exposed from the insulating film 22.
It is structured as. The electrodes 23, 2
4 and the external connection terminals 25, 26 are nickel-plated or gold-plated on a copper foil. On the wiring board thus formed, the light emitting diode element 7 is mounted on the one electrode 23 as in the conventional case, and the thin metal wire 8 is formed on the upper surface of the other electrode 24 from the light emitting diode element 7.
Is wire-bonded and the light-transmitting resin 9 seals the electrodes 23 and 24 so as to cover the light-emitting diode element 7 and the thin metal wire 8.

As a means for exposing the back surfaces of the electrodes 23 and 24, for example, as shown in FIGS. 5 and 6, a plurality of the chip type light emitting diodes 21 are formed by using a collective wiring film (insulating film 22). When individually picking up, first, electrodes 23 and 24 are formed by etching or the like on an insulating film 22 having one surface coated with copper foil, and then a part of the insulating film 22 is melted down by etching or burned off by laser processing. The electrodes 23,
It is possible to form the notches 33 and 34 in which the back surface side of 24 is exposed. In this embodiment, by using a polyimide film as the insulating film 22, it is possible to easily and accurately remove the film by etching or laser processing.

The pair of electrodes 23 thus formed,
24, the light emitting diode element 27 is arranged in parallel on one electrode 23 as shown in FIG. 7 and bonded using a conductive adhesive such as silver paste, and then the light emitting diode element 27 and the other electrode 24 And are wire-bonded with the thin metal wire 28. Further, the electrodes 23 and 24 are sealed with a transparent resin 29 so as to cover the light emitting diode element 27 and the thin metal wire 28.

In the next step, as shown in FIG.
The respective light emitting diode elements 27 are cut by using a dicing machine or the like, and separated into individual chip type light emitting diodes 21 as shown in FIG.

Next, the case where the chip type light emitting diode 21 having the above structure is mounted on a printed circuit board will be described. 3 and 4, reference numeral 30 is an insulating base material, and 31 is a conductor pattern wired on the insulating base material 30. In this case, as shown in FIG.
1 is coated with a conductive bonding material 32 such as solder or silver paste in advance, and the chip type light emitting diode 21 is formed on the conductive bonding material 32.
Is placed. The insulating film 22 is formed on the conductive bonding material 32.
Both ends of the electrode are placed, and the external connection terminals 25 and 26 formed on the respective back surfaces of the pair of electrodes 23 and 24 are connected to the conductor pattern 3.
It will be in the form of facing 1. At this time, a gap corresponding to the thickness of the insulating film 22 is formed between them, but the insulating film 22 according to this embodiment is formed of a polyimide film and has a very thin thickness of 50 μm. The thickness of the portions 33 and 34 does not hinder solder wettability and soldering stability.

Next, when the printed circuit board is put in a heating furnace in this state, the conductive bonding material 32 previously coated on the conductor pattern 31 is softened, and as shown in FIG. Notch 33, 34 wetted to the back side of 24
And are fixed to the external connection terminals 25 and 26. Therefore, the external connection terminals 25 and 26 are electrically connected to the conductor pattern 31 via the conductive bonding material 32.

FIGS. 8 and 9 show a second embodiment of the chip type light emitting diode according to the present invention. In this chip type light emitting diode 35, the cutout portions 33, 34 of the external connection terminals 25, 26 in the previous embodiment are plated with metal or the like to form the conductors 36, 37, thereby forming an external connection with the lower surface of the insulating film 22. It is made flat by eliminating the step between the terminals for use 25 and 26. That is, in the above-described embodiment, a part of the insulating film 22 is removed by etching or laser processing to expose the back surfaces of the electrodes 23 and 24, and then the notches 33 and 34 are entirely metal-plated to form a conductor. 36, 37 are formed, and finally, the electrodes 23, 24 and the conductors 36, 37 are plated with nickel, gold, solder or the like to form flat external connection terminals 25, 26 having no step with the lower surface of the insulating film 22. can do.

When the chip type light emitting diode 35 having such a structure is mounted on the insulating base material 30, the chip is mounted on the conductor pattern 31 of the insulating base material 30 as shown in FIGS. Conductive bonding material 3 applied on the conductor pattern 31 when the light emitting diode 35 is placed.
2 and the conductors 36 and 37 of the chip type light emitting diode 35 can be completely brought into close contact with each other, the stability when mounted and the wettability of the solder are further improved. The attachment stability is improved.

12 and 13 show a third embodiment of the chip type light emitting diode according to the present invention. The chip type light emitting diode 40 according to this embodiment is provided with a pair of holes 41 and 42 reaching the back surfaces of the electrodes 23 and 24 on the left and right sides of the insulating film 22, and the electrodes 23 exposed by the holes 41 and 42. , 24 are formed as the external connection terminals 43, 44 on the back side. In the chip type light emitting diode 40, unlike the previous embodiment, the insulating film 22 has the same size as the electrodes 23 and 24, so that the substrate strength is increased and the handling becomes easy.

FIGS. 14 and 15 show a case where the chip type light emitting diode 40 having the above structure is mounted on the insulating base material 30. First, as shown in FIG. 14, the insulating film 22 is placed so that the holes 41 and 42 are located directly above the conductive bonding material 32 applied on the conductor pattern 31. Next, when the conductive bonding material 32 is softened by placing it in a heating furnace in this state, as shown in FIG. 15, a part of the conductive bonding material 32 wets up to the insides of the holes 41 and 42, and each electrode. It is fixed to external connection terminals 43 and 44 located on the back side of 23 and 24. Therefore, the external connection terminals 43 and 44 are electrically connected to the conductor pattern 31 via the conductive bonding material 32. In this embodiment also, the holes 41, 42 may be plated with metal to form conductors.

Although a polyimide film is used as the insulating film 22 in the above embodiment, it is of course possible to use other types of films in the present invention. Further, the glass epoxy resin substrate similar to the conventional one can be used without being limited to the insulating film 22 as in the above embodiment. Further, in the above-mentioned embodiment, as means for exposing the back surfaces of the electrodes 23, 24, the cutouts 33, 34 and the holes 4 are formed in the insulating film 22.
Although the case where 1, 42 are formed has been described, the present invention is not limited to these means.

[0029]

As described above, according to the chip type light emitting diode of the present invention, a pair of electrodes is formed on the upper surface of the insulating substrate, and the back side of the electrodes is exposed from the insulating substrate for external connection. Since it has a two-layer structure as a terminal, it is possible to achieve a thinner structure than the conventional three-layer structure without deteriorating the thermal and mechanical reliability required for the chip type light emitting diode. In particular, when an extremely thin polyimide film or the like is used in place of the conventional glass epoxy resin substrate, an extremely thin chip type light emitting diode can be made, and an insulating substrate for exposing the back side of the electrode can be formed. The notch or hole can be easily formed by etching, laser processing, or the like.

Further, since the chip type light emitting diode of the present invention uses an insulating substrate having a single-sided copper foil clad, it does not require plating on the through-hole unlike the conventional double-sided substrate, so that the number of working steps is simplified, As a result, it has become possible to manufacture an inexpensive chip type light emitting diode.

Further, since the notches and the like provided on the insulating substrate are metal-plated to form conductors and the steps between the external connection terminals and the lower surface of the insulating substrate are eliminated as much as possible, the conductive material such as solder applied to the printed circuit board is electrically conductive. The external connection terminals are in close contact with the flexible bonding material, and the solder wettability during bonding is further improved, enabling more stable solder mounting.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a chip type light emitting diode according to the present invention.

2 is a cross-sectional view taken along the line AA of the chip type light emitting diode shown in FIG.

FIG. 3 is a cross-sectional view before mounting the chip type light emitting diode shown in FIG. 1 on a printed board.

FIG. 4 is a cross-sectional view after mounting the chip type light emitting diode shown in FIG. 1 on a printed circuit board.

5 is a perspective view showing an intermediate step of the collective wiring board in the manufacturing process of the chip type light emitting diode shown in FIG. 1. FIG.

6 is a perspective view showing a completed state of the collective wiring board in the manufacturing process of the chip type light emitting diode shown in FIG. 1. FIG.

7 is a perspective view showing a state in which light emitting diode elements are mounted on a collective wiring board in a manufacturing process of the chip type light emitting diode shown in FIG. 1. FIG.

FIG. 8 is a perspective view showing a second embodiment of the chip type light emitting diode according to the present invention.

9 is a cross-sectional view taken along line BB of the chip type light emitting diode shown in FIG.

FIG. 10 is a cross-sectional view before mounting the chip type light emitting diode shown in FIG. 8 on a printed board.

11 is a cross-sectional view after mounting the chip type light emitting diode shown in FIG. 8 on a printed board.

FIG. 12 is a third view of the chip type light emitting diode according to the present invention.
It is a perspective view showing an example.

13 is a cross-sectional view of the chip type light emitting diode shown in FIG.

14 is a cross-sectional view before mounting the chip type light emitting diode shown in FIG. 12 on a printed board.

15 is a cross-sectional view after mounting the chip type light emitting diode shown in FIG. 12 on a printed board.

FIG. 16 is a perspective view showing an example of a conventional chip type light emitting diode.

FIG. 17 is a C-type of the chip type light emitting diode shown in FIG.
It is a C line sectional view.

FIG. 18 is a cross-sectional view showing another example of a conventional chip type light emitting diode.

[Explanation of symbols]

 21 Chip Type Light Emitting Diode 22 Insulating Film (Insulating Substrate) 23 Electrode 24 Electrode 25 External Connection Terminal 26 External Connection Terminal 27 Light Emitting Diode Element 28 Metal Fine Wire 29 Transparent Resin 33 Notch 34 Notch 35 Chip Type Light Emitting Diode 36 Conductor 37 Conductor 40 Chip type light emitting diode 41 Hole 42 Hole 43 External connection terminal 44 External connection terminal

Claims (4)

[Claims] 1. A pair of electrodes is provided on the upper surface of an insulating substrate, a light emitting diode element is mounted on the surface side of one electrode, and the light emitting diode element and the surface side of the other electrode are wire-bonded with a fine metal wire. While sealing the light emitting diode element and the thin metal wire with a light-transmissive resin, a part of each back surface side of the pair of electrodes is exposed from an insulating substrate, and the exposed surface is a terminal for external connection of the electrode. A chip-type light emitting diode characterized in that 2. The chip type light emitting diode according to claim 1, wherein a notch or a hole is provided in the insulating substrate to expose the back surface side of the electrode. 3. The chip type light emitting diode according to claim 2, wherein the notch or hole provided in the insulating substrate is plated with metal to form a conductor. 4. The chip type light emitting diode according to claim 1, wherein the insulating substrate is a polyimide film having a thickness of 20 to 50 μm.