JPH01192572A - Mounting structure of wiring board - Google Patents

Abstract

PURPOSE:To enable electronic apparatus to be miniaturized and to improve reliability of the wiring connection, by a method wherein for an electronic circuit device mounted on a wiring board arranged by extending along a breaking away direction near a component, an electrode for said input is fixed to an electrode on a surface of the wiring board. CONSTITUTION:A surface of a wiring board 28, to which the LED 25 and driving IC 30 thereof are fixed, is approximately so arranged as to be included in a plane made by an axis and a bus of a photosensitive drum 22. Thereby, a mounting space for write 23 becomes a space W2. Since a space occupied by the write head 23 is decreased thereby, miniaturization of a LED printer 21 is realized. Further, continuity between a driving IC 30 and a wiring conductor 27 of the wiring board 28 is obtained by a metal pump 51, and the driving IC 30 is connected to an electrode on an anode side of the LED 25 via the metal bump 51, the wiring conductor 27, and a metal bump 46. In the write head 23, reliability of the wiring connection is improved thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a so-called LED (light emitting diode), which performs printing by selectively irradiating the surface of a photoreceptor using a light emitting diode to form an electrostatic latent image. ) The present invention relates to a mounting structure of a wiring board suitably implemented in a printer or the like.

2. Description of the Related Art An LED (light emitting diode) is configured to selectively illuminate a charged photoreceptor drum with light generated from an LED (light emitting diode) to form an electrostatic latent image on the surface of the photoreceptor drum.
Printers are conventionally used. FIG. 4 shows a photosensitive drum 2 of an LED printer 1 having such a configuration.
The basic configuration around the is shown.

Associated with the photoreceptor drum 2 is a write head 3 extending in the longitudinal direction thereof. The write head 3 generates light for forming an electrostatic latent image on the surface of the photoreceptor drum 2 . The write head 3 has an L in which a plurality of light emitting parts 4 arranged along the longitudinal direction of the photoreceptor drum 2 are formed.
ED5 is provided. The LED5 has a driving IC (
A signal voltage corresponding to data to be printed out is supplied from the integrated C1reuit 6. The plurality of light emitting parts 4 of the LED 5 selectively emit light based on a signal given from the driving IC 6.

The LED 5 and the driving IC 6 are arranged on the wiring board 7. The arrangement board 7 is made of a material such as alumina ceramics, and a pattern of wiring conductors 8 is formed on its surface. The cathode side electrode of the LED 5 is die-bonded to the wiring conductor 8. Further, the driving TC 6 is electrically connected to the wiring conductor 8 by the bonding wire 9, and the LED
It is connected to the anode side electrode of No. 5 via a bonding wire 10 and a wiring conductor 8. One bonding wire 9, 1o is used for each of the plurality of light emitting parts 4 of the LED 5.

The light generated from the light emitting section 4 of the LED 5 is transmitted to the photosensitive drum 2.
The light is focused on the surface of the photoreceptor drum 2 by a rod lens array 11 extending along the longitudinal direction. When printing, the photosensitive drum 2 is used, for example, in the direction indicated by the arrow R in FIG.
Rotates in one direction.

On the surface of the photoreceptor drum 2, the photoreceptor drum 2 is charged on the upstream side in the arrow R1 direction from the position indicated by the reference numeral 15 that is irradiated with light from the light emitting section 4 of the LED 5 through the rod lens array 11. A charger (not shown) is provided for this purpose, and the surface of the photoreceptor drum 2 is uniformly charged by this charger. An electrostatic latent image can be formed on the photoreceptor drum 2 by scanning the photoreceptor drum 2 with light from the writing head 3 in such a state and selectively removing the charge. Therefore, the photoreceptor drum 2 is
When the LED 5 is being rotated in the direction
C6, and the plurality of light emitting sections 4 may selectively emit light in accordance with the data to be printed out.

The electrostatic latent image formed on the photoreceptor drum 2 is converted into a toner image by a developing bag (not shown) provided downstream in the direction of arrow R1 from the position indicated by reference numeral 15 on the photoreceptor drum 2. The toner image is visualized and transferred to the recording paper, thereby performing printing on the recording paper.

Problems to be Solved by the Invention Although the writing head 3 is mounted in the LED printer 1, a mounting space W1 shown in the fourth figure is required in the vicinity of the photosensitive drum 2 at this time. When downsizing the LED printer 1, the diameter of the photosensitive drum 2 is reduced. By reducing the diameter of the photoreceptor drum 2, a space is created near the photoreceptor drum 2 to mount a charger, a developing device, a static eliminator for removing the electrostatic latent image formed on the photoreceptor drum 2, etc. becomes smaller. Therefore, when downsizing the LED printer 1, it is desirable that the mounting space W1 is as small as possible.Furthermore, when the LED printer 1 performs color printing, the configuration of the developing device etc. becomes large. In order to secure the mounting space, the mounting space W1 of the write hept 3 must be made small.

In the write head 3, the connection between the anode side electrode of the LED 5 and the driving IC 6, and the connection between the driving IC 6 and the wiring conductor 8 are made by bonding wires 9 and 10, respectively. When printing is performed on a recording paper number, for example, about 3,500 light emitting parts 4 are formed in the LED 5. That is, in this case, printing is performed on recording paper at a density of 3500 dots per scanning line. In this case, the bonding wire 9 is connected to one light emitting part 4, that is, one dot.
．． Since two bonding wires of 10 are required,
Approximately 7000 bonding wires are required. In such a state, mutual contact between the bonding wires and breakage of the bonding wires are likely to occur, and the function of the write head 3 may not be fulfilled. In addition, the reliability of wire bonding affects the reliability of the writing pad 3, and the number of man-hours required for wire bonding is extremely large, making it impossible to reduce production costs.

Furthermore, the wiring conductor indicated by reference numeral 8a in FIG. 4, that is, the wiring conductor to which the cathode side electrode of the LED 5 is connected, is used as a common electrode of the LED 5, so a relatively large current flows through this wiring conductor. flows. For example, when all the light emitting parts 4 are emitting light, the IO
Current exceeding A may flow. On the other hand, the wiring conductor is 1
Since the thickness is approximately several micrometers, heat generated by the current cannot be ignored near the wiring conductor indicated by reference numeral 8a, and this heat generation reduces the intensity of light emitted from the light emitting portion 4 of the LED 5.

An object of the present invention is to provide a wiring board mounting structure that solves the above-mentioned technical problems, enables miniaturization of electronic devices such as LED printers, and improves the reliability of wiring connections. .

Means for Solving the Problems The present invention provides a wiring board mounted near one component in an electronic device, the wiring board being arranged extending along a direction away from the component near the component, The electronic circuit elements mounted on the wiring board are
This is a mounting structure of a wiring board on which an electronic circuit element is mounted, characterized in that a C pole is fixed to an electrode on the surface of the wiring board.

Operation In the present invention, a wiring board mounted near one component in an electronic device is arranged to extend along a direction away from the component. The input electrodes of the electronic circuit elements mounted on the wiring board are fixed to electrodes on the surface of the wiring board.

This reduces the mounting space for the wiring board near the above-mentioned components, and also reduces the space required for the input of electronic circuit elements.
Since bonding wires and the like are not used to connect the poles to the electrodes on the surface of the wiring board, the reliability of wiring connections related to the wiring board is improved.

Embodiment FIG. 1 is a sectional view showing the basic structure of an LED (light emitting diode) printer 21 in the vicinity of a photosensitive drum 22 according to an embodiment of the present invention.

The photosensitive drum 22 is rotationally driven in the direction of arrow R2 when printing is performed, and its surface is scanned by light from the writing head 23 to form an electrostatic latent image. The light generated from the @include head 23 illuminates the photoreceptor drum 22 at a position indicated by reference numeral 24 on the photoreceptor drum 22 .

1jlfil on photosensitive drum 22! A charger (not shown) is provided at a position upstream of the position indicated by reference numeral 24 in the direction of arrow R2. The photosensitive drum 22 is uniformly charged by this band 1.

In this state, the writing head 23 selectively irradiates a scanning line parallel to the axis of the photoreceptor drum 22 at a position indicated by reference numeral 24, thereby selectively illuminating the surface of the photoreceptor drum 22 on the scanning line. By removing the charge, an electrostatic latent image is formed on the photoreceptor drum 22. The static latent image thus formed is converted into a toner image by a developing device (not shown), and this toner image is transferred onto recording paper, thereby performing printing on the recording paper.

The write head 23 is provided with an LED 25, which will be described later. The LED 25 is fixed to a wiring board 28 in which a wiring conductor 27 is formed on one surface of a transparent substrate 26 made of a material such as glass. An electrode on the anode side of the LED 25 is connected to a wiring conductor 27 by a configuration described later.

On the open surface of the wiring board 28 where the wiring conductor 27 is formed, a transparent resin N29 having a thickness equal to the thickness of the wiring conductor 27 is formed on a portion where the wiring conductor 27 is not formed.

The LED 25 is a driving IC (Integrate
dCircuit) 3 Q. The driving rc 30 is connected to the wiring conductor 27 of the wiring board 28 by a configuration described later. The wiring board 28 is
The surface to which D25 and drive IC 30 are fixed is
Roughly, the photosensitive drum 22 is arranged so as to be included in a plane formed by the axis and the generatrix.

The LED 25 is formed with a plurality of light emitting parts 31 arranged in parallel to the axial direction of the photoreceptor drum 22, and these light emitting parts 31 are arranged facing the wiring board 28 for the configuration of the LED 25, which will be described later. That will happen.

A conductive tape 32 is fixed to the cathode side of the LED 25 using silver paste or the like. The conductive tape 32 may be made of copper wire knitted into a cloth shape, for example, and the surface of the conductive tape 32 opposite to the LED 25 is fixed to a metal cover 33. Although the conductive tape 32 is a wiring conductor formed on the wiring board 28 and must be connected to a wiring conductor (not shown), such a connection mode is not shown in FIG. is not connected to any of the wiring conductors 27 of the wiring board 28.

On the cathode side of LED25! Although the poles are used as common electrodes, and therefore a relatively large current flows through the conductive tape 32, the conductive tape 32 does not generate heat to an undesirable degree even when a large current flows through it. Even if heat is generated, the metal cover 33
The amount of heat generated is released to the outside.

A reflector 1 m 34 is provided on the side of the wiring board 28 opposite to the side to which the LED 25 and the driving IC 30 are fixed. A rod lens array 35 is interposed between the reflecting mirror 34 and the photosensitive drum 22. The light emitted from the light emitting part 31 of the LED 25 passes through the transparent resin layer 29 and the transparent substrate 26, is reflected by the reflecting mirror 34, and is focused by the rod lens array 35 to the position indicated by reference numeral 24 on the photosensitive drum 22. irradiate.

The driving IC 30 and the electrode on the anode side of the LED 25 are connected via a wiring conductor 27, so that the LED 25 is activated based on a signal given from the driving IC 30.
In this case, light is selectively emitted from the plurality of light emitting parts 31.The light emitted from the light emitting parts 31 illuminates the photosensitive drum 22 at the position indicated by reference numeral 24, so the LED
By driving the drive IC 30 to emit light in accordance with the content of the desired print output, the desired print output can be obtained on the recording paper.

A heat sink 36 for heat dissipation in relation to the driving IC 30 is provided on the side of the wiring board 28 where the reflecting mirror 34 is disposed.
will be placed. Since the driving IC 30 is thereby shielded by the metal cover 33 and the heat sink 36, the influence of external electromagnetic noise on the driving IC 30 can be reduced.

FIG. 2 is a sectional view showing the configuration of the LED 25. L.E.
D25 includes an N-type semiconductor layer 41 and a P-type semiconductor layer 42. The vicinity of the P-type semiconductor layer 42 is the light emitting section 31 described above. An anode-side electrode 43 is connected to the P-type semiconductor layer 42, and a cathode-side electrode 44 is formed on the N-type semiconductor N41. The N-type semiconductor layer 41 and the electrode 43 are insulated by an insulating layer 45. The electrode 44 on the cathode side is the conductive tape 3 shown in FIG.
2 and is bonded with silver paste or the like.

The electrodes 43 on the anode side have small bumps (hereinafter referred to as metal bumps) for each electrode 43 made of a material such as solder or gold.
46 is formed. Electrical connection between the electrode 43 and the wiring conductor 27 of the wiring board 28 is obtained through this metal pan 146.

The connection between the pole 43 and the wiring conductor 27 of the wiring board 28 is made by the metal pan 146; when the metal bump 46 is formed using, for example, solder, the metal bump 46 is connected after the LED 25 is crimped toward the wiring board 28. This is done by heating and melting the solder.

No. 312I is a cross-sectional view of the driving IC 30. Although the driving IC 30 is provided with a plurality of terminals for inputting and outputting signals, a metal bump 51 is formed in association with each terminal. By this metal bump 51, the driving I
C30 can obtain electrical continuity with the wiring conductor 27 of the wiring board 28.

As described above, in this embodiment, the surface of the wiring board 28 to which the LED 25 and the driving IC 30 are fixed is
Roughly, the photosensitive drum 22 is arranged so as to be included in a plane formed by the axis and the generatrix. That is, the wiring board 28
are arranged to extend in a direction away from the photoreceptor drum 22.

As a result, the mounting space for the write head 23 corresponding to the mounting space W1 shown in FIG. 4 becomes the mounting space W2 shown in FIG. 1. As a result, the photoreceptor drum 2
2, the space occupied by the write head 23 becomes significantly smaller, so even if the diameter of the photoreceptor drum 22 is reduced, there is still enough space around it for installing a charger, a static eliminator, a developing device, etc. You can take it. This allows the LED printer 21 to be made smaller.

Further, electrical conduction between the driving IC 30 and the wiring conductor 27 of the wiring board 28 is obtained by a metal bump 51, and between the driving IC 30 and the anode side electrode of the LED 25,
Metal bump 51, wiring conductor 27, and metal pan 146
connected via.

This eliminates the need to use bonding wires for wiring connections, thus greatly improving the reliability of the wiring connections in the write head 23.

Also common 1 in LED 25! The cathode side electrode 44 serving as a pole is connected to a wiring conductor (not shown) of the wiring board 28 via the conductive tape 32. The conductive tape 32 does not generate an undesirable amount of heat even when subjected to a large current, and even if the conductive tape 32 generates heat, the conductive tape 32 is bonded to the metal cover 33.
The generated heat is released to the outside via the metal cover 33.

This stabilizes the light emission intensity of the LED 25.

Effects of the Invention As described above, according to the present invention, it is possible to reduce the mounting space of a wiring board mounted near one component in an electronic device, so that as a result of downsizing the component, the component Even when the nearby space is reduced, components other than the wiring board can be mounted in the vicinity of the component, which is advantageous for downsizing electronic equipment. In addition, the connection of electronic circuit elements mounted on the wiring board is
There is no need for wire bonding, etc., and the reliability of wiring connections related to the wiring board is significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the basic structure of a portion related to the photosensitive drum 22 of an LED printer 21 according to an embodiment of the present invention, FIG. 2 is a sectional view showing the structure of the LED 25, and FIG.
The figure is a sectional view showing the structure of the driving IC 30, and FIG. 4 is a sectional view showing the basic structure around the photosensitive drum 2 of the conventional LED printer 1. 21...LED printer, 22...photosensitive drum,
23...Writing head, 25...LED, 28...
・Wiring board, 30...Drive IC132...Conductive tape, 43.44...Electrode, 46.51...Metal bump agent Patent attorney Number of strokes Keiichi Shimadai 2;]

Claims (1)

[Scope of Claims] A wiring board mounted near one component in an electronic device, wherein the wiring board is arranged so as to extend in a direction away from the component in the vicinity of the component, and the wiring board is mounted on the wiring board. A mounting structure of a wiring board on which an electronic circuit element is mounted, characterized in that the input electrode of the electronic circuit element is fixed to an electrode on the surface of the wiring board.