JP2003347596A - Optical semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical semiconductor device in which reliability is enhanced by enhancing adhesion strength of a substrate and a sealing resin material, and adhesion strength of the substrate and conductive paste. <P>SOLUTION: An LED 23 is bonded through conductive paste 30 to the mount part 26 of a circuit pattern 25 formed on the surface of a substrate 22 having an insulating basic material 24 and applied with gold plating on the surface, and then it is sealed with an epoxy resin sealing member 33. The mount part 26 has an area not larger than the area at the bonded bottom face of the LED 23. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device such as a surface mount type LED lamp.

[0002]

2. Description of the Related Art The prior art will be described with reference to FIGS. FIG. 7 is a plan view of the substrate, and FIG. 8 is a sectional view.

In FIGS. 7 and 8, reference numeral 1 denotes a surface-mount type LED lamp. An LED 3 is fixed on the upper surface of a substrate 2 by using a conductive paste 4 containing silver (Ag) as a conductive material. The sealing member 5 is formed of a sealing resin material made of an epoxy resin. Further, the substrate 2 is provided with a mount portion 7 for fixing the LED 3 and a wire bonding portion 8 on an upper surface side of a base material 6 made of an insulating material mainly composed of, for example, bismaleimide triazine and glass fiber. The circuit pattern 11 including the outer electrode portions 9 and 10 provided with the connection portions 9a and 10a on the mount portion 7 and the wire bonding portion 8 respectively from the opposing upper edge portion to the lower surface side is made of a conductive material such as copper. Alternatively, it is formed of a copper alloy, and the surface of the circuit pattern 11 is plated with gold (Au).

When the substrate 2 has a vertical and horizontal dimension of, for example, 2.0 mm × 1.25 mm, the mounting portion 7 has a square shape of 600 μm × 600 μm, and a square having a bottom surface of 200 μm × 200 μm. Eggplant LED3
Is fixed and mounted. The LED 3 is provided with an upper electrode 12 having a diameter of 100 μm on the upper surface.
3 is fixed to the mounting portion 7, and the upper surface electrode 12 and the wire bonding portion 8 are bonded to the bonding wire 1 of Au wire.
3 are bonded at both ends, and the size of a contact portion with the surface of the substrate 2 after bonding is 1.4 mm × 1.2.
Sealing is performed by molding a sealing member 5 of 5 mm with a sealing resin material.

As described above, the size of the mounting portion 7 is determined in consideration of the dimensional variation of the LED 3 and the forming accuracy of the mounting portion 7 so that the LED 3 does not protrude from the mounting portion 7 at the time of fixing. 10 than the size of the bottom
The size was set to 0 μm or more. When the migration phenomenon of the conductive paste 4 is taken into consideration, the size of the mount 7 is further increased so that the conductive paste 4 applied to the mount 7 does not protrude.

[0006] However, in the above prior art,
When the size of the mount 7 increases, the Au plating and the sealing member 5 applied to the surface of the mount 7 accordingly.
The area in contact with the epoxy resin increases. A
Since u is an inert substance, the adhesiveness with the epoxy resin is poor, and the adhesive strength between the substrate 2 and the sealing member 5 is low. In addition, since the conductive paste 4 is applied to the surface of the Au-plated mount portion 7 to fix the LED 3, the adhesion strength between the substrate 2 and the conductive paste 4 is similarly low, and the fixing strength of the LED 3 is also low. Was not too expensive.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to increase the adhesion strength between a substrate and a sealing member and the adhesion strength between a substrate and a conductive paste. Another object of the present invention is to provide an optical semiconductor device with improved reliability.

[0008]

An optical semiconductor device according to the present invention comprises an optical semiconductor chip fixed to a mount portion of a circuit pattern formed on a substrate surface with a conductive paste and sealed with a sealing resin material. In the optical semiconductor device, the mount portion has an area equal to or smaller than the area of the fixed bottom surface of the optical semiconductor chip, and further includes the sealing resin material. Is an epoxy resin, wherein the mounting portion is plated with gold, and an optical semiconductor chip is mounted on a mounting portion provided in a circuit pattern formed on the surface of the substrate. In the optical semiconductor device fixed with a conductive paste so as to be electrically connected to the circuit pattern and sealed with a sealing resin material, the mount portion is
An exposed surface of a substrate formed on a substrate, wherein the optical semiconductor chip is fixed to the surface of the substrate with the conductive paste and is electrically connected to the circuit pattern by the conductive paste. Is what you do.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment will be described with reference to FIGS. 1 is a sectional view, FIG. 2 is a plan view of a substrate, FIG. 3 is a plan view showing a state before a sealing member is formed, and FIG. 4 is a sectional view of a main part.

1 to 4, reference numeral 21 denotes an LED lamp, which is a surface-mount type optical semiconductor device. The LED lamp 21 has, for example, an upper surface of a substrate 22 formed in a square shape having a vertical and horizontal dimension of 2.0 mm × 1.25 mm. A rectangular parallelepiped LED 23 of an optical semiconductor chip is fixed and mounted on a predetermined portion. The substrate 22 is made of, for example, bismaleimide triazine and glass fiber as a main part, and a circuit pattern of a predetermined shape formed of a conductive material such as copper or a copper alloy on a base material 24 made of an insulating material containing an epoxy resin. 25 is provided from the upper surface to the lower surface.

The circuit pattern 25 has a mount portion 26 having a diameter of 200 μm at a substantially central portion on the upper surface side of the substrate 22, and further has a width corresponding to 0.
A 25 mm wire bonding portion 27 is provided at a distance, and external electrode portions 28 and 29 are provided from the upper surface edge portion of the opposing base material 24 to the lower surface side. The outer electrode portions 28, 29, the mount portion 26, and the wire bonding portion 27 are connected with corresponding portions by providing connection portions 28a, 29a each having a width of 0.25 mm. The surface of the circuit pattern 25 is plated with gold (Au).

The mount 26 includes an LED 23.
However, the bottom surface forming a square of 200 μm × 200 μm is formed by using a conductive paste 30 made of epoxy resin containing silver (Ag) as a conductive material, and the center of the bottom surface is located substantially at the center of the mount portion 26. So that it is mounted. Further, the fixing by the conductive paste 30 is performed by first applying the conductive paste 30 to the mound portion 26 so as to protrude from the outer periphery when the LED 23 is fixed, and then mounting the LED 23 on the mound portion 26. Note that the bottom surface of the LED 23 is
6 protrudes from the outer periphery of the base material 24 and the space A
In this case, the space A may be filled with the conductive paste 30 by applying the conductive paste 30 around the lower part of the LED 23.

An LED fixed to the mount 26
One end of a bonding wire 32 of an Au wire is bonded to an upper surface electrode 31 having a diameter of 100 μm provided on the upper surface, and the other end of the bonding wire 32 is bonded to a wire bonding portion 27. When bonding the bonding wire 32, a vertical bonding pressure is applied to the upper surface electrode 31,
Although a large force is also applied to the LED 23, the mount portion 26 is formed in such a size that the upper surface electrode 31 does not protrude from the area immediately above the mount portion 26 even when processing errors and assembly errors are taken into consideration. By fixing the LED 23 so that the center of the bottom of the LED 23 is located substantially at the center, a biased force is not applied to the LED 23, and the LED 23 is not damaged.

After bonding, a truncated pyramid-shaped sealing member 33 having a size of 1.4 mm × 1.25 mm in contact with the surface of the substrate 22 is formed of a sealing resin material made of an epoxy resin. Sealing is performed by L
The ED lamp 21 is completed. Then, the LED lamp 21
Indicate the external electrode portions 28,
29 is surface-mounted by soldering by reflow or the like.

By configuring the LED lamp 21 as described above, the total area S of the contact between the sealing member 33 and the substrate 22 is 1.75 mm ² , whereas, for example, the conductive paste 30 Is 200 μm, which is equal to the diameter of the mount 26, the length of the Au-plated connection portion 28a sealed by the sealing member 33 made of epoxy resin is 0.45 mm, and the wire bonding is performed. The length of the part 27 and the connecting part 29a is 0.25 m
When m, the area _{S a} is approximately 0.175 mm ² next to Au plating part of the circuit pattern 25 surface, the area _{S a} of the Au plating portion corresponds to approximately 10% of the total area S.

On the other hand, the size shown in the prior art is 6
A mounting portion 7 of 00 μm × 600 μm is provided on the substrate 2 at the same position as in the present embodiment, the diameter of the conductive paste 4 applied to the mounting portion 7 is set to 200 μm, and the sealing member 5 made of epoxy resin is used. Assuming that the length of the Au-plated connection portion 9a to be sealed is 0.25 mm and the length of the wire bonding portion 8 and the connection portion 10a is 0.25 mm, the conductive paste 4 of the mount portion 7 is not applied. including the part, the area _{S b} of the Au-plated portions of the circuit pattern 11 surface substantially 0.454Mm ^2, and the area _{S b} of the Au plating portion corresponds to approximately 25.9 percent of the total area S.

As a result, in the present embodiment, the area where the Au plating portion comes into contact with the sealing member 33 is greatly reduced. For this reason, the contact area between the epoxy resin of the sealing resin material and the base material 24 increases, and the substrate 22 and the sealing member 3
The adhesion strength of No. 3 increases. Further, the conductive paste 30
Also, not only does the contact with the Au plating surface of the mount portion 26, but also a portion thereof comes into contact with the base material 24 to fix the LED 23, so that the adhesion strength between the conductive paste 30 and the substrate 22 increases, and the The LED 23 can be fixed to the LED lamp 21 and the reliability of the LED lamp 21 can be improved.

In the above embodiment, the shape of the mounting portion 26 is a circle having a diameter the same as the length of one piece of the square bottom surface of the LED 23 mounted on the substrate 22. Square,
Alternatively, the LED 23 may have a smaller area than the square bottom surface, and may have a shape that does not hinder the assembling in which a predetermined adhesion strength is obtained.

Next, a second embodiment will be described with reference to FIGS. FIG. 5 is a plan view of the substrate, and FIG. 6 is a sectional view. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The configuration of the present embodiment that is different from the first embodiment will be described.

5 and 6, reference numeral 41 denotes an LED lamp, which is a surface-mount type optical semiconductor device. The LED lamp 41 is, for example, an upper surface of a substrate 42 formed in a square shape having a vertical and horizontal dimension of 2.0 mm × 1.25 mm. A rectangular parallelepiped LED 23 of an optical semiconductor chip is fixed and mounted on a predetermined portion. In addition, the substrate 42 includes a base material 24 made of an insulating material, a conductive material,
For example, a circuit pattern 43 having a predetermined shape made of copper or a copper alloy is provided from the upper surface to the lower surface.

The circuit pattern 43 is formed such that a mounting area 44 where the upper surface of the base material 24 is exposed is provided at the center of the upper surface side of the substrate 42 so that the outer electrode portion extends from the upper edge to the lower surface of the opposing base material 24. 28, 29, a connection portion 28a extends from the upper surface side of one external electrode portion 28 toward the mount region 44, and a wire extends from the upper surface side of the other external electrode portion 29 toward the mount region 44. The bonding portion 27 extends so as to provide the connection portion 29a. The surface of the circuit pattern 43 is plated with gold (Au).

The LED 2 is provided in the mount area 44.
3 uses a conductive paste 30 in which the epoxy resin contains silver (Ag) as a conductive material, and the center of the bottom is located substantially at the center of the mount region 44. It is mounted by fixing so that The conductive paste 30
First, the connection area 28a is attached to the mount area 44.
Conductive paste 3 having a diameter of about 200 μm so that
0 is applied, and then the LED 23 is mounted on the conductive paste 30 applied to the mount area 44.

The LE fixed to the mount area 44
One end of a bonding wire 32 of an Au wire is bonded to an upper electrode 31 having a diameter of 100 μm provided on the upper surface of D23.
The other end of the bonding wire 32 is bonded.

After the bonding, the sealing is performed by molding a sealing member 33 made of an epoxy resin, and the LED lamp 41 is completed. Further, the formed LED lamp 41 is surface-mounted on a mounting portion on the surface of a wiring board (not shown) by soldering the external electrode portions 28 and 29 by reflow or the like.

With such a configuration, also in the present embodiment, as in the first embodiment, the area where the Au plating portion and the sealing member 33 are in contact is greatly reduced. As a result, the contact area between the epoxy resin and the base material 24 increases, the adhesion strength between the substrate 42 and the sealing member 33 increases, and the adhesion strength between the conductive paste 30 and the substrate 42 further increases. The effect that the LED 23 can be more firmly fixed can be obtained.

[0027]

As is apparent from the above description, according to the present invention, the adhesion strength between the substrate and the sealing resin material of the sealing member and the adhesion strength between the substrate and the conductive paste are increased, and the reliability of the device is improved. The effect is that the performance can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a first embodiment of the present invention.

FIG. 2 is a plan view of a substrate according to the first embodiment of the present invention.

FIG. 3 is a plan view showing a state before molding a sealing member according to the first embodiment of the present invention.

FIG. 4 is a sectional view of a main part according to the first embodiment of the present invention.

FIG. 5 is a plan view of a substrate according to a second embodiment of the present invention.

FIG. 6 is a sectional view showing a second embodiment of the present invention.

FIG. 7 is a plan view of a substrate according to the related art.

FIG. 8 is a sectional view showing a conventional technique.

[Explanation of symbols]

22, 42 ... substrate 23… LED 24 ... Base material 25, 43 ... circuit pattern 26 ... Mount section 44… Mount area

Claims (3)

[Claims] 1. An optical semiconductor device comprising an optical semiconductor chip fixed to a mount portion of a circuit pattern formed on a substrate surface with a conductive paste and sealed with a sealing resin material, wherein the mount portion has an area corresponding to the area of the mount portion. Is equal to or smaller than the area of the fixed bottom surface of the optical semiconductor chip. 2. The optical semiconductor device according to claim 1, wherein the sealing resin material is an epoxy resin, and the mount portion is plated with gold. 3. A light obtained by fixing an optical semiconductor chip to a mount portion provided on a circuit pattern formed on a substrate surface with a conductive paste so as to conduct the circuit pattern, and sealing the chip with a sealing resin material. In the semiconductor device, the mount portion is an exposed surface of a substrate formed on a substrate, and the optical semiconductor chip is fixed to a surface of the substrate with the conductive paste and the circuit is formed by the conductive paste. An optical semiconductor device characterized by being electrically connected to a pattern.