JPH05338251A - Electrostatic recording head - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an electrostatic recording head in which the cross wiring substrate and the needle electrode substrate are reliably bonded. [Structure] In a conventional electrostatic recording head, a needle electrode substrate 12
The upper solder resist is applied over the entire portion to which the cross wiring board 16 is bonded. However, even if the adhesive is made of the same epoxy resin as the solder resist, the adhesive strength of the adhesive to the solder resist is not so strong. Therefore, most of the solder resist of the solder resist formed on the needle electrode substrate 12 to which the cross wiring substrate 16 is attached is removed so that the adhesive 20 is directly applied to the needle electrode substrate 12. Thereby, the cross wiring substrate 16 and the needle electrode substrate 1
Adhesive strength with 2 becomes sufficient.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic recording head used for an electrostatic plotter or the like.

[0002]

2. Description of the Related Art FIG. 2 is an overall perspective view of a typical electrostatic recording head with a side plate partially cut away. The needle electrodes 10 are formed of copper foil in a stripe shape on both sides of a needle electrode substrate 12 made of glass epoxy or the like, and their tips are linearly arranged in the main scanning direction. Both sides of this tip portion are sandwiched by the side plates 14. The recording paper (not shown) is transported along the side plate 14 in the sub-scanning direction of arrow A at a predetermined feed timing. By applying a voltage based on the image signal to the needle electrode 10 in a predetermined order while the recording sheet is being transferred, an electrostatic pattern of an image corresponding to the image signal is recorded on the recording sheet.

A cross wiring board 16 for laterally extending the wiring is further adhered to the needle electrode board 10. The material of the cross wiring board 16 is also glass epoxy. Wirings extending in the length direction of the cross wiring substrate are formed on the back surface of the cross wiring substrate 16, that is, the surface facing the needle electrode substrate 12, and these wirings pass through through holes provided in the substrate. And extends to the front side, and is connected to a bonding pad formed on the front side surface of the substrate.

Further, on the needle electrode substrate 12, a large number of driving integrated circuits 18 having a shift register for converting a serial signal into a parallel signal and a voltage conversion circuit are mounted side by side in a lateral direction. These integrated circuits 18 are connected to the needle electrodes 10 and wire-bonded to the above-mentioned bonding pads provided on the cross wiring substrate.

FIG. 3 is a partial sectional view of the electrostatic recording head shown in FIG. As shown in the figure, the integrated circuit 18 and the cross wiring board 16 are both provided with an epoxy resin adhesive 20.
Is attached to the needle electrode substrate 12. In addition, solder resists 22 and 24 are applied to the bonding surfaces of the needle electrode substrate 12 and the cross wiring substrate 16. This solder resist is for preventing solder from being attached to an unnecessary place on the surface of the substrate. By providing this solder resist, it is possible to prevent the wiring on the surface of the substrate from being short-circuited by unnecessary solder or the like.

[0006]

By the way, if an adhesive is used through a solder resist when the cross wiring substrate is bonded to the needle electrode substrate, the adhesive strength between the solder resist and the adhesive is weak. The board may peel off or float. Especially when wire-bonding the leads of the integrated circuit after bonding both substrates,
Since the force for fixing the entire substrate during bonding, heat and vibration for bonding are applied to the substrate,
There is a high risk that the cross wiring board and the needle electrode board will separate.
Further, although the solder resist is applied to both the needle electrode substrate and the cross wiring substrate, it has been empirically recognized that the solder resist applied to the needle electrode substrate and the adhesive are particularly easily peeled off. When the needle electrode substrate and the cross wiring substrate are peeled off in this way, there arises a problem that the electrostatic recording head does not function.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrostatic recording head in which the adhesion between the cross wiring substrate and the needle electrode substrate is ensured.

[0008]

The present invention for achieving the above object provides a cross wiring substrate having a solder resist formed on a surface thereof, and a needle electrode substrate having a solder resist formed on the surface thereof, wherein the solder resist is In an electrostatic recording head formed by bonding the formed surfaces to each other so as to face each other, a part of a part of the surface of the needle electrode substrate facing the cross wiring substrate where the cross wiring substrate is bonded or Remove all solder resist,
Alternatively, the cross wiring substrate is bonded to the needle electrode substrate without forming a solder resist from the beginning.

[0009]

According to the present invention, when the cross wiring substrate is attached to the needle electrode substrate by the adhesive, the solder resist of the portion to which the cross wiring substrate is attached is solder resist applied on the needle electrode substrate. The adhesive directly contacts the needle electrode substrate by removing part or all of the solder paste or not forming the solder resist from the beginning, so that the adhesive strength between the cross wiring substrate and the needle electrode substrate is sufficient. Become.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partial cross-sectional view of an electrostatic recording head which is an embodiment of the present invention and corresponds to FIG. Therefore, in FIG. 1, components having the same functions as those shown in FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted. In the conventional electrostatic recording head, as shown in FIG. 3, the solder resist on the needle electrode substrate 12 is applied over the entire portion to which the cross wiring substrate 16 is bonded, but in this embodiment, as shown in FIG. Most of the solder resist of the portion to which the cross wiring board 16 is bonded is removed.

Since the solder resist is for preventing unnecessary solder and the like from adhering to the wiring portion formed on the substrate, its surface tension is generally made small. Therefore, even if the adhesive is made of the same epoxy resin as the solder resist, the adhesive strength of the adhesive to the solder resist is not so strong. Therefore, in this embodiment, most of the solder resist formed on the needle electrode substrate 12 to which the cross wiring substrate 16 is attached is removed, and the adhesive 20 is applied directly to the needle electrode substrate 12. I am doing it. As a result, the cross wiring substrate 16 and the needle electrode substrate 12
Adhesive strength with is sufficient.

By the way, the solder resist is also applied to the cross wiring substrate 16, and when the cross wiring substrate 16 is attached to the needle electrode substrate 12, the cross wiring substrate 1 is used.
Since the solder resist 22 on 6 also comes into contact with the adhesive 20, there is a concern that the adhesive strength between the two will decrease. However, the empirical fact that the solder resist and the adhesive on the side of the cross wiring board 16 are unlikely to be peeled off even if the solder resist is interposed therebetween is recognized,
In this embodiment, the surface of the cross wiring board 16 is protected by leaving the solder resist on the cross wiring board 16 side as it is. However, if the cross wiring board 16 and the adhesive 20 are easily peeled off, it is possible to remove all or part of the solder resist 20 on the cross wiring board 16 side.

The present invention is not limited to the above embodiments, but various modifications can be made within the scope of the invention. For example, in the above embodiment, the case where the solder resist is once formed on the needle electrode substrate 12 and then the solder resist in a predetermined portion is removed has been described. However, when the solder resist is applied to the needle electrode substrate, It is also possible to prevent the solder resist from being applied to a predetermined portion. Further, in the above embodiment, a part of the solder resist on the portion to which the cross wiring substrate is attached is removed, but the entire solder resist on the portion to which the cross wiring substrate is applied may be removed. Further, in the above embodiment, the case where the needle electrodes are formed on both surfaces of one needle electrode substrate has been described, but a large number of needle electrode substrates on one surface of each of the two needle electrode substrates are arranged at a constant pitch. A needle electrode is formed and the surfaces of the two needle electrode substrates on which the needle electrodes are not formed are bonded, or the surfaces of the two needle electrode substrates on which the needle electrodes are formed are insulated. You may use what was pasted together through.

[0014]

As described above, according to the present invention, a part or all of the solder resist of the portion of the needle electrode substrate facing the cross wiring substrate, to which the cross wiring substrate is bonded, is removed or Or, by bonding the cross wiring substrate without forming the solder resist from the beginning, the adhesive for adhering the cross wiring substrate directly contacts the needle electrode substrate, so the adhesive strength between the cross wiring substrate and the needle electrode substrate Therefore, it is possible to provide the electrostatic recording head in which the cross wiring substrate is not easily peeled off from the needle electrode substrate even when force, vibration, heat or the like is applied during wire bonding.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an electrostatic recording head that is an embodiment of the present invention.

FIG. 2 is an overall perspective view of a typical electrostatic recording head with a side plate partially cut away.

FIG. 3 is a partial cross-sectional view of a conventional electrostatic recording head.

[Explanation of symbols]

 10 Needle electrode 12 Needle electrode substrate 14 Side plate 16 Cross wiring substrate 18 Integrated circuit 20 Adhesive 22, 24, 26 Solder resist

Claims (2)

[Claims] 1. A cross wiring substrate having a solder resist formed on the surface thereof is bonded to a needle electrode substrate having a solder resist formed on the surface so that the surfaces on the side where the solder resist is formed face each other. In the electrostatic recording head, part or all of the solder resist of the portion of the surface of the needle electrode substrate facing the cross wiring substrate where the cross wiring substrate is bonded is removed, or the solder resist is formed from the beginning. An electrostatic recording head, characterized in that the cross wiring substrate is attached to the needle electrode substrate without doing so. 2. The solder resist is partially or entirely removed from a portion of the surface of the cross wiring substrate facing the needle electrode substrate, the portion being bonded to the needle electrode substrate, or
Alternatively, the electrostatic recording head according to claim 1, wherein the solder resist is not formed from the beginning.