JPH08156324A - Mounting device for protective cover in LED array head - Google Patents

Abstract

PURPOSE: To strengthen adhesion and lessen irregularity in dimension by forming, on a bottom face of a protective cover, a recess to be filled with an adhesive in a manner extending over the whole periphery. CONSTITUTION: On a top face of a circuit substrate 1, a light emitting semiconductor chip 2 consisting of a number of light emitting elements 2a arranged in a row on its top face is mounted. At the right and left sides, controlling semiconductor chips 3 and 4 for flashing an optional light emitting element out of the light emitting elements 2a are mounted. Further, a protective cover 10 is adhered to a base coat 9 formed on a top face of a resin coat 6 on the circuit substrate 1 by an adhesive 11 such as a UV type adhesive applied to a bottom face 10a of the protective cover 10 or the base coat 9, so as to fix to the circuit substrate 1. At a part near the inner periphery of the bottom face 10a of the protective cover 10, a recess 12 is formed in a manner extending over the whole periphery of the protective cover 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED used as a line light source in an electrophotographic printer or a display.
In an array head, the present invention relates to a device for attaching a protective cover for covering a semiconductor chip mounted on a circuit board to the circuit board.

[0002]

2. Description of the Related Art Generally, an LED array head of this type includes a light emitting semiconductor chip formed on a top surface of a circuit board by arranging a large number of light emitting element portions in a line.
A control semiconductor chip for controlling blinking of any light emitting element portion of each light emitting element portion in this light emitting semiconductor chip is mounted, and the light emitting semiconductor chip and the control semiconductor chip are further provided on the upper surface of the circuit board. A cap is formed so as to cover the entire chip, and a protective cover body in which at least a portion corresponding to the light emitting semiconductor chip is transparent is attached by an adhesive or the like.

[0003]

In this type of LED array head, light from each light emitting element portion of the light emitting semiconductor chip is emitted from the upper surface of the transparent portion through the transparent portion of the protective cover body. Therefore, it is necessary to make the upper surface of the transparent portion of the protective cover body parallel to the upper surface of the light emitting semiconductor chip, and at the same time, the transparent portion of the protective cover body from the upper surface of the light emitting semiconductor chip. It is necessary to keep the distance to the upper surface of the.

Despite this, in the conventional LED array head, as described above, the protective cover body is fixed to the upper surface of the circuit board with an adhesive, so that the protective cover body is Depending on the amount of adhesive sandwiched between the lower surface and the upper surface of the circuit board, the parallelism between the upper surface of the transparent portion of the protective cover body and the upper surface of the light emitting semiconductor chip, and the protective cover from the upper surface of the light emitting semiconductor chip. Variation will occur in the distance to the upper surface of the transparent portion of the body.

Therefore, in the conventional LED array head, the variation between the parallelism and the distance is reduced by minimizing the amount of the adhesive sandwiched between the lower surface of the protective cover and the upper surface of the circuit board. However, if the amount of adhesive used is small, the adhesive strength of this adhesive is considerably reduced, and since the thermal expansion difference absorption by the adhesive is low, the temperature In weathering tests such as lowering or raising the temperature, there is a problem that the protective cover body often comes off the circuit board or a gap is formed between the protective cover body and the circuit board.

The present invention is technically intended to reduce variations in parallelism and distance without causing the above-mentioned problems when the protective cover body is fixed to the circuit board with an adhesive. This is an issue.

[0007]

In order to achieve this technical object, the present invention provides a "light emitting semiconductor chip having a plurality of light emitting element portions arranged in a line on the upper surface of a circuit board, and A semiconductor chip for control for each light emitting element portion of the semiconductor chip for light emission is mounted, and the semiconductor chip for light emission and the semiconductor chip for control are formed in a cap shape so as to cover the whole, and at least the semiconductor chip for light emission. In an LED array head formed by fixing a protective cover body having a transparent portion at a portion corresponding to the above with an adhesive, a recess for filling the adhesive with the lower surface of the protective cover body is provided. It is formed so as to extend over the entire circumference of the protective cover body. "

[0008]

[Operation] As described above, by forming the recess filled with the adhesive on the lower surface of the protective cover body so that the recess extends over the entire circumference of the protective cover body, a sufficient amount can be provided in the recess. The lower surface of the protective cover body can be directly brought into contact with the upper surface of the circuit board, or the amount of the adhesive sandwiched between them can be made very small, with the adhesive of FIG. .

[0009]

Therefore, according to the present invention, the lower surface of the protective cover body can be directly brought into contact with the upper surface of the circuit board, or the amount of the adhesive sandwiched between them can be reduced, so that the protective cover can be protected. It is possible to reliably reduce the parallelism between the upper surface of the transparent portion of the cover body and the upper surface of the light emitting semiconductor chip and the variation in the distance from the upper surface of the light emitting semiconductor chip to the upper surface of the transparent portion of the protective cover body. On the other hand, the adhesive in the recess on the lower surface of the protective cover body can significantly increase the adhesive strength and can reliably absorb the difference in thermal expansion between the protective cover body and the circuit board. This has the effect of greatly reducing the possibility that the body will come off the circuit board and that a gap will be created between them.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 8 show a first embodiment. In the figure, reference numeral 1 indicates a circuit board, and on the upper surface of the circuit board 1, a light emitting semiconductor chip 2 formed by arranging a plurality of light emitting element portions 2a in a line on the upper surface is mounted. , On the left and right sides of this light emitting semiconductor chip 2,
Control semiconductor chips 3 and 4 for controlling blinking of any light emitting element portion of each light emitting element portion 2a in the light emitting semiconductor chip 2 are mounted.

On the upper surface of the circuit board 1, the connection terminal electrodes 5 for the control semiconductor chips 3 and 4 are provided.
Various circuit wiring patterns 5 for electrically connecting a to each of the external connection terminal electrodes 5b are formed, and the epoxy resin-based green resin coat 6 is used for the various circuit wiring patterns. It is formed so as to cover 5.
The control semiconductor chips 3 and 4 are mounted on the upper surface of the resin coat 6, and a thin metal wire 7 is provided between the light emitting semiconductor chip 2 and the control semiconductor chips 3 and 4. It is electrically connected by wire bonding, and also between the control semiconductor chips 3 and 4 and the connection terminal electrodes 5a of the various circuit wiring patterns 5,
It is electrically connected by wire bonding with a thin metal wire 8.

Furthermore, on the upper surface of the resin coat 6 in the circuit board 1, a white base film 9 made of an epoxy resin-based synthetic resin is formed on the upper surface of the resin coat 6 as in the resin coat 6 for controlling the light emitting semiconductor chip 2 and both. It is formed so as to surround the semiconductor chips 3 and 4. Reference numeral 10 indicates a protective cover body formed of transparent synthetic resin such as polycarbonate in a substantially rectangular cap shape so as to cover the entire light emitting semiconductor chip 2 and both control semiconductor chips 3 and 4.

The protective cover body 10 is attached to the circuit board 1
To the lower surface 10a of the protective cover body 10 or the base film 9 applied to the upper surface of the resin coat 6 in FIG. By adhering with the adhesive 11, it is fixed to the circuit board 1. In this case, the recess 12 is provided in the inner surface of the lower surface 10a of the protective cover body 10 so that the recess 12 extends over the entire circumference of the protective cover body 10.

Thus, the lower surface 10 of the protective cover body 10
a is provided with a recess 12 so that the recess 12 extends over the entire circumference of the protective cover body 10 so as to be applied to the lower surface 10a of the protective cover body 10 or
Since most of the adhesive 11 applied to the base film 9 is filled in the recess 12, the protective cover body 10 is provided with a sufficient amount of the adhesive 11 secured in the recess.
The lower surface 10a can directly contact the base film 9 on the upper surface of the circuit board 1, or the amount of the adhesive 11 sandwiched therebetween can be made small.

As a result, the parallelism between the upper surface of the protective cover body 10 and the upper surface of the light emitting semiconductor chip 2 and the variation in the distance L from the upper surface of the light emitting semiconductor chip 2 to the upper surface of the protective cover body are varied. While the size can be surely reduced, the adhesive strength in the recess 12 on the lower surface 10a of the protective cover body 10 can be significantly increased, and the adhesive strength between the protective cover body 10 and the circuit board 1 can be increased. It is possible to reliably absorb the difference in thermal expansion.

As a second embodiment, as shown in FIGS. 9 and 10, on the lower surface 10a of the protective cover body 10,
The groove-shaped recess 12 ′ may be provided so that the groove-shaped recess 12 ′ extends over the entire circumference of the protective cover 10. In the case of the present embodiment, the protective cover body 10 is, as described above,
In addition to being fixed to the circuit board 1 with the adhesive 11, the pins 13 integrally provided at each of the four corners of the protective cover body 10 are inserted into the pin holes 14 formed in the circuit board 1. After that, the tip end of each pin 13 is fixed on the back surface side of the circuit board 1 by pressing the heating element A axially against it and caulking and deforming it with heat.

[Brief description of drawings]

FIG. 1 is a perspective view of an LED array head according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a perspective view showing a state in which a protective cover body is disassembled.

FIG. 5 is an enlarged perspective view of a circuit board.

6 is an enlarged sectional view taken along line VI-VI of FIG.

FIG. 7 is a bottom view taken along the line VII-VII in FIG.

FIG. 8 is a diagram showing a state in which the pins of the protective cover body are inserted into the pin holes of the circuit board.

FIG. 9 is a vertical sectional front view according to a second embodiment of the present invention.

FIG. 10 is a bottom view taken along line XX of FIG. 9.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circuit board 2 Light emitting semiconductor chip 3,4 Control semiconductor chip 5 Circuit wiring pattern 6 Resin coat 9 Base film 10 Protective cover body 10a Lower surface of protective cover body 11 Adhesive 12 Recess

Claims (1)

[Claims] 1. A light emitting semiconductor chip having a plurality of light emitting element portions arranged in a line on the upper surface of a circuit board,
A control semiconductor chip for each light emitting element portion of the light emitting semiconductor chip is mounted, and the light emitting semiconductor chip and the control semiconductor chip are formed in a cap shape so as to cover the whole, and at least the light emitting semiconductor chip is formed. In an LED array head formed by fixing a protective cover body having a transparent portion at a portion corresponding to a chip with an adhesive, a recess for filling the adhesive with the lower surface of the protective cover body,
An apparatus for mounting a protective cover in an LED array head, wherein the recess is formed so as to extend over the entire circumference of the protective cover body.