JPH09232732A - Printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the insulation resistance between circuit patterns from being reduced due to a coverlay film by a method wherein open parts, which are positioned between the circuit patterns, are formed in the coverlay film. SOLUTION: In a printed board 1, a copper foil is pasted to the surface of a base film, this copper foil is performed an etching or the like and a coverlay film 5 is provided in such a way as to cover circuit patterns 4. A sequence controller 2, a rock crystal oscillator 3 and the like are mounted on the board 1. The controller 2 is made to have an electrical continuity with the oscillator 3 by the patterns 4 formed on the base film Open parts 5a, 5b and 5e are formed in the photosensitive covering film 5. Open parts 5c and 5d formed in the film 5 are formed also in land parts 4a for soldering the oscillator 3 to the patterns 4. Thereby, a reduction in an insulation resistance between the pattens 4 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board having a coverlay film for covering and protecting a circuit pattern, and more particularly to a flexible printed circuit board.

[0002]

2. Description of the Related Art A flexible printed circuit board is formed by forming a circuit pattern on a polyimide base film by etching or the like and then using a punching means or the like to cover a polyimide coverlay film on the base film so as to cover the circuit pattern. It is made by pasting on. By covering the circuit pattern with the cover lay film in this way,
The circuit pattern can be protected electrically and mechanically.

Some coverlay films are made of a photosensitive film, and the photosensitive coverlay film is vacuum-laminated with a dry film on a base film on which a circuit pattern has been formed to prevent exposure and chemical treatment. It is mounted on the base film by performing heat curing at the end.

When such a photosensitive coverlay film is used, the coverlay film can be finely processed as compared with the case where a polyimide film is used, so that the degree of freedom of wiring on the flexible printed circuit board is increased, It is possible to reduce the size and cost of the flexible printed circuit board.

[0005]

However, when the flexible printed circuit board covered with the photosensitive cover lay film is placed under high temperature and high humidity, the insulation resistance between the circuit patterns arranged close to each other is increased by the polyimide cover. There is a possibility that it will be lower than that covered with a ray film.
Then, the reduction of the insulation resistance leads to the problem that the functions of the electric components (for example, the sequence controller and the crystal oscillator) on the substrate are degraded. Therefore, a first object of the present invention is to provide a printed wiring board in which the insulation resistance between circuit patterns is not reduced by the coverlay film (particularly, the photosensitive coverlay film).

[0006]

In order to achieve the above object, in the first invention of the present application, in a printed circuit board in which the surface of a substrate on which a circuit pattern is formed is covered with a coverlay film, a circuit is formed on the coverlay film. Openings located between the patterns are formed.

That is, a portion of the photosensitive coverlay film that covers between the two circuit patterns is removed to form an opening, thereby preventing a decrease in insulation resistance between the circuit patterns due to the photosensitive coverlay film. However, the malfunction of electric parts such as a crystal oscillator connected to the circuit pattern is avoided.

If only the land portion of the two circuit patterns to which the terminal leads of the electric parts are connected is close to each other and the portions other than the land portion are sufficiently separated, the space between the land portions is You may form an opening only in.

Further, according to the second aspect of the present invention, in the printed circuit board in which the surface of the substrate on which the circuit pattern is formed is covered with the coverlay film, the coverlay film is formed with the opening along the outer periphery of the circuit pattern. .

That is, not only the portions between the circuit patterns but also the outer portions of these circuit patterns are surrounded by the openings of the coverlay film to insulate the conductive portions around these circuit patterns from each other. It is also possible to prevent a decrease in resistance.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIGS. 1 and 2 show a flexible printed circuit board according to a first embodiment of the present invention.
In the figure, 1 is a flexible printed circuit board,
As shown in FIG. 2, in this printed circuit board 1, a copper foil is attached to the surface of a base film 11 with an adhesive 12, the copper foil is etched or the like to form a circuit pattern 4, and the circuit pattern 4 is formed. The cover lay film 5 is provided so as to cover it. On this printed circuit board 1,
Electrical components such as the sequence controller 2 and the crystal oscillator 3 are mounted.

Reference numeral 4 denotes a copper pattern formed on the base film 11, which electrically connects the sequence controller 2 mounted on the substrate 1 and the crystal oscillator 3 to each other. Reference numeral 5 is a photosensitive coverlay film that electrically and mechanically protects the copper pattern 4, and is surrounded by a chain line in the figure.
Reference numerals a, 5b, and 5e are openings formed in the photosensitive coverlay film 5. Reference numeral 4a denotes a land portion for soldering the crystal oscillator 3 to the copper pattern 4, and openings 5c and 5d of the coverlay film 5 are also formed on the land portion 4a.

Next, regarding the relationship between the copper pattern 4 which electrically connects the sequence controller 2 and the crystal oscillator 3 in the above-mentioned structure, and the photosensitive coverlay film 5 formed around the copper pattern 4. explain. First, the sequence controller 2 is mounted on the substrate 1 by soldering the terminal leads 2a to the copper pattern group 7 exposed through the openings 5a and 5b of the photosensitive coverlay film 5. A part of the copper pattern group 7 is connected to the circuit pattern 4.

The crystal oscillator 3 has a land portion 4a, which is exposed through openings 5c and 5d of the coverlay film 5,
The terminal lead 3a is soldered to 4a and mounted on the substrate 1. The crystal oscillator 3 is arranged as close as possible to the sequence controller 2 so that the capacitance change of the copper pattern 4 tangential between the crystal oscillator 3 and the sequence controller 2 is minimized when the sequence controller 2 is activated. Has been done.

Then, two copper patterns 4 and 4 serving as input / output terminals of the crystal oscillator 3 extend adjacent to each other with a required space. The upper portion of the copper pattern 4 excluding the land portion 4a is covered with a photosensitive coverlay film 5, but the portion between the two copper patterns 4 and 4 is exposed along the edge line of the copper pattern 4. 5e of the transparent coverlay film is formed. The opening 5e is formed so as to be connected to the mounting opening 5b of the sequence controller 2.

As described above, by covering the copper pattern 4 with the coverlay film 5, the copper pattern 4 can be protected electrically and mechanically, while the photosensitive cover is provided between the copper patterns 4 and 4. Ray film 5 opening 5e
By forming the adhesive and exposing the adhesive 12, the insulation resistance between these two copper patterns 4 and 4 does not decrease even under high temperature and high humidity conditions, and the oscillation failure of the crystal oscillator 3 is prevented. You can

As shown in FIG. 2, each copper pattern 4
And the coverlay film 5 between the other conducting part (not shown).
It is desirable to form the opening 5f in order to prevent the insulation resistance between each copper pattern 4 and other conductive portions from decreasing.

(Second Embodiment) Next, a flexible printed circuit board according to a second embodiment of the present invention will be described with reference to FIG.

In this figure, 21 is a flexible printed circuit board, on which a sequence controller 22 and a crystal oscillator 23 are mounted. Of the copper pattern groups 27, 27 to which the terminal leads of the sequence controller 22 are soldered, two copper patterns 2 sandwiching the corners of the sequence controller 22.
4, 24 extend to the crystal oscillator 23 side, and terminal leads of the crystal oscillator 23 are soldered to the land portions 24a at the tips of the copper patterns 24, 24.

A photosensitive coverlay film 25 is provided on the surface of the printed circuit board 1, and openings 25a, 25b, 25c of the coverlay film 25 are provided on the land portions 24a of the copper pattern group 27 and the copper pattern 24. 25d
Is formed to allow soldering with each terminal lead.

Here, a sufficient distance is provided between the two copper patterns 24, 24 arranged at the corners of the sequence controller 22 so that the photosensitive coverlay film 25 does not cause insufficient insulation resistance. However, the space between the lands 24a, 24a is narrowed because the terminal leads of the crystal oscillator 23 are soldered.

Therefore, the opening 25e of the photosensitive coverlay film 25 is formed between the land portions 24a 24a, and the land portion 24 formed by the photosensitive coverlay film 25 is formed.
The crystal oscillator 2 is prevented from lowering the insulation resistance between a and 24a.
The oscillation failure of No. 3 is avoided.

(Third Embodiment) Next, a flexible printed circuit board according to a third embodiment of the present invention will be described with reference to FIG.

In this figure, 31 is a flexible printed board, and a sequence controller 32 and a crystal oscillator are soldered to copper patterns 34 and 37 formed on the board 31. This printed circuit board 31
The surface of the is covered with a photosensitive coverlay film 35, but on the upper part of the part (land part 34a etc.) to which the 35 sequence controller 32 on the copper patterns 34, 37 and the terminal lead of the crystal oscillator 33 are soldered. The cover lay film 35 has openings 35a, 35b, 35c and 35d formed therein.

Further, a photosensitive coverlay film 35 is formed around the two copper patterns 34, 34 arranged in close proximity.
The opening 35c is formed. For this reason, the copper resistances 34, 34 connecting the sequence controller 32 and the crystal oscillator 33 do not become insufficient in insulation resistance due to the coverlay film 35.

The present invention may use the above-described embodiments and modified examples, or the technical elements thereof in combination as necessary.

(Relationship Between Embodiment and Claims) In the above embodiment, the copper patterns 4, 24 and 34 are in the conductive patterns referred to in the claims, and the photosensitive coverlay films 5, 25 and 35 are claimed. The openings 5e, 25e and 35c correspond to the coverlay film in the scope and the openings in the claims, respectively.

The above is the correspondence relationship between each configuration of the present invention and each configuration of the embodiment, but the present invention is not limited to the configuration of these embodiments, and the mechanism or the embodiment described in the claims is not limited thereto. Any structure may be used as long as the function of the structure can be achieved.

[0029]

As described above, in the first invention of the present application, the cover lay film is deleted between the circuit patterns (between the land portions when the land portions are close to each other). Then, it is used as an opening. Therefore, according to the present invention, even when a photosensitive coverlay film is used, it is possible to prevent the insulation resistance between circuit patterns from being lowered due to the presence of the film, and the malfunction of the electric parts connected to these circuit patterns is prevented. Can be reliably avoided.

Further, in the second invention of the present application, not only the portions between the circuit patterns but also the portions outside these circuit patterns are surrounded by the openings of the coverlay film.
Therefore, according to the present invention, it is possible to reliably prevent a decrease in insulation resistance between the circuit pattern and the conductive portion around the circuit pattern.

[Brief description of drawings]

FIG. 1 is a plan view of a flexible printed circuit board according to a first embodiment of the present invention.

2 is a cross-sectional view taken along the line II-II in FIG.

FIG. 3 is a plan view of a flexible printed circuit board according to a second embodiment of the present invention.

FIG. 4 is a plan view of a flexible printed circuit board according to a third embodiment of the present invention.

[Explanation of symbols]

1 Flexible Printed Circuit Board 2 Sequence Controller 3 Crystal Oscillator 4 Copper Pattern 5 Photosensitive Coverlay Film 5a-5e, 25a-25e, 35a-35c Opening (of Coverlay Film) 11 Base Film

Claims (5)

[Claims] 1. A printed circuit board in which a surface of a circuit board on which a circuit pattern is formed is covered with a coverlay film, wherein the coverlay film has openings formed between the circuit patterns. 2. The printed circuit board according to claim 1, wherein the opening is formed between lands of the circuit pattern to which terminal leads of electric parts are connected. 3. The printed circuit board according to claim 2, wherein the electric component is a crystal oscillator. 4. A printed circuit board in which the surface of a circuit board on which a circuit pattern is formed is covered with a coverlay film, wherein an opening is formed in the coverlay film along the outer periphery of the circuit pattern. . 5. The printed circuit board according to claim 1, wherein the coverlay film is made of a photosensitive film.