JPH0582935A - Printed wiring board - Google Patents

Abstract

PURPOSE:To provide a printed wiring board excellent in precision equipped with suitable and uniform resistors. CONSTITUTION:Between lands 13, 13 of a pattern circuit 12 provided on an insulating substrate 11 provided are an insulating base layer 15 and an underresist layer 14 equipped with air gaps 18 leaving junctions, and junctions and air gaps 18 are printed with carbon paste to form a resistor 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a printed wiring board,
In particular, the present invention relates to a printed wiring board in which a resistance portion is provided by printing in a printed wiring circuit.

[0002]

2. Description of the Related Art Conventionally, a resistance portion required in a pattern circuit of a printed wiring board is mounted by soldering a resistor composed of a chip component to a resistance junction portion previously formed in the pattern circuit. Although it has been carried out, in recent years, instead of forming a resistance part by mounting such a chip component, a carbon paste is printed by screen printing, and by curing this, between the resistance joint parts in the pattern circuit of the printed wiring board. A method of forming a resistance portion has been developed and implemented.

FIG. 8 shows a printed wiring board in which a resistance portion is formed between joints in a pattern circuit by the same method, and in FIG. 8, 1 is a printed wiring board,
2 is a pattern circuit formed on the upper side of the substrate 3 of the printed wiring board 1, 4 is a pattern circuit 2 formed on the upper side of the substrate 3, and the bonding portions 2a and 2b of the resistor portions are left on the pattern circuit 2 upper side. The applied resist, 5 is the resist 4
After forming, the carbon paste is screen-printed and cured to show the resistance portion formed between the joint portions 2a and 2b in the pattern circuit 2.

[0004]

However, in the printed wiring board 1 in which the conventional carbon paste is screen-printed and cured to form the resistance portion 5 between the joint portions 2a and 2b in the pattern circuit 2, , The joints 2a, 2
Between b, there is a step corresponding to the thickness of the joints 2a and 2b (usually the thickness of the copper foil of 35 μm), and due to the stepped portion, the screen printing of the carbon paste itself is blurred, especially the joints 2a and 2b. It was difficult for the carbon paste to enter the edge portions 2c and 2d, and printing scraping occurred, which was a cause of product failure due to performance deterioration of the resistance portion 5 itself due to momentum, joint failure of the same portion, and the like. Therefore, the present invention has been developed in view of the drawbacks in forming a resistance portion in such a printed wiring board, and an object of the present invention is to provide a printed wiring board capable of preventing the occurrence of print blur when printing a carbon paste. It is what

Another object of the present invention is to provide a printed wiring board in which the durability of the resistance portion and the resistance value adjustment measures are taken into consideration especially in order to prevent such scraping.

[0006]

A printed wiring board according to the present invention is a printed wiring board in which a resistance portion is formed by printing a resistance paste between joint lands in a printed wiring circuit. An insulating underlayer is provided between them, a void portion for resistance adjustment is provided, and the resistance portion is formed through the insulating underlayer and the void portion.

[0007]

According to the present invention, when the resistor portion is printed by the resistor paste, the insulating paste is provided between the joint portions in the pattern circuit so that the step portion between the joint portions is removed. The printing can be performed, and the voids provided between the joint portions can be used while adjusting the resistance value and improving the joint action by increasing the joint area of the resistor portion.

[0008]

[Embodiment 1] FIG. 1 shows a first embodiment of the printed wiring board of the present invention, and is a sectional view taken along the line AA of FIG. 2, and FIG. 2 is a plan view of the essential portions showing the first embodiment of the printed wiring board of the present invention. 3 and 4
Shows the main part of the first embodiment of the printed wiring board of the present invention during the manufacturing process, FIG. 3 is a sectional view taken along the line BB of FIG. 4, and FIG. 4 is a plan view of the main part.

In the figure, 10 is a printed wiring board of the present invention, 11 is an insulating substrate of the printed wiring board 10, 12 is a pattern circuit formed on the upper side of the insulating substrate 11, and 13 is a resistance portion in the pattern circuit 12. , 14 is an under resist layer formed on the upper side of the pattern circuit 12, and 15 is an under resist layer 14
The insulating underlayer formed between the bonding land portions 13 at the same time as the formation of the insulating underlayer, 18 for forming the insulating underlayer 15 and a void for resistance adjustment provided in the recess of the underlayer 15, and 16 for the bonding land. The resistance portions are formed between the joint portions 17 of the portions 13 with the insulating underlayer 15 interposed and the void portion 18 filled with the resistance paste.

Therefore, the resistance portion 16 in the printed wiring board 10 is formed after the insulating base layer 15 and the void portion 18 are provided through the steps of FIGS. 3 and 4. That is, after the pattern circuit 12 is formed on the upper side of the insulating substrate 11 by a known method, the pattern circuit 12 is formed.
A resistance portion 1 having a required resistance value between the junction land portions 13 of
6 is formed by printing a carbon paste and forming an under-resist layer 14 provided on the upper side of the pattern circuit 12 prior to curing and forming the carbon paste. The under resist is screen-printed while leaving the joint 17 between the land portions 13 to form the insulating base layer 15 and the void portion 18 between the joined land portions 13 (Note that the void portion 18 is a joined portion when the under resist is screen-printed. It can be formed by the presence of 17 steps).

Then, in order to form the resistance portion 16 between the bonding land portions 13, a carbon paste having a required composition is screened between the bonding land portions 13 with the insulating underlayer 15 interposed therebetween. By printing by printing and curing the same, the resistance portion 16 is formed between the joint land portions 13 while being electrically connected through the joint portions 17 of the joint land portions 13. At the same time, the amount of the resistance paste at the time of printing the resistance paste can be adjusted by the void portion 18, and the resistance value of the resistance portion 16 between the joint portions 17 can be arbitrarily adjusted and selected.

The insulating underlayer 15 is formed at the same time when the under resist layer 14 is formed, but it may be formed in connection with the step of forming another resist layer, for example, a solder resist film. It is also possible to form the resist portion 16 separately from the formation of the resist film and prior to the formation of the resistance portion 16.

[0013]

[Embodiment 2] FIGS. 5, 6 and 7 show a second embodiment of the printed wiring board of the present invention, and FIG. 5 is a view taken along line CC of FIG. A sectional view, FIG. 6 is a plan view of the same, and FIG. 7 is a sectional view of a printed wiring board.

In these drawings, reference numeral 20 denotes the printed wiring board of the second embodiment. In the printed wiring board 10 of the first embodiment, the bonding land is formed when the insulating base layer 15 is formed. Although the void 18 is formed by the recess formed by the step between the portions 13, in this embodiment, as shown in FIGS. 5 and 6, the insulating base layer 1 formed at the same time as the formation of the under resist layer 14 is formed.
5 is formed by leaving the void 18.

Therefore, the other structure and manufacturing method are the same as those in the first embodiment, and therefore the description thereof will be omitted. In FIGS. 5, 6 and 7, the same components as those in the first embodiment will be designated by the same reference numerals. Is attached.

[0016]

According to the present invention, when the resistance portion formed in the circuit of the printed wiring board is formed by a printing method such as screen printing, an insulating underlayer is interposed between the joint portions of the resistance portion. By forming the resistance portion by forming the resistance portion, it is possible to form in a state in which the step between the joint portions is removed,
Prevents blurring during printing of the resistance paste forming the resistance portion, forms a proper and uniform resistance portion, and adjusts the resistance value of the resistance portion by the void portion while bonding strength with the underlying layer. It is possible to improve the manufacturing accuracy of this kind of printed wiring board.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a printed wiring board according to the present invention.

FIG. 2 is a plan view of essential parts showing a first embodiment of the printed wiring board according to the present invention.

FIG. 3 is a cross-sectional view showing the main parts of the printed wiring board according to the first embodiment of the present invention during the manufacturing process.

FIG. 4 is a plan view of a main part of FIG.

FIG. 5 is a cross-sectional view showing Example 2 of the printed wiring board of the present invention, showing a state in which an insulating underlayer and voids are formed.

FIG. 6 is a plan view of the second embodiment.

FIG. 7 is a cross-sectional view of the printed wiring board of Example 2.

FIG. 8 is a cross-sectional view showing a conventional printed wiring board.

[Explanation of symbols]

 1, 10 Printed wiring board 2, 12 Pattern circuit 3, 11 Insulating substrate 4, 14 Under resist layer 6, 16 Resistance part 2a, 2b, 13 Bonding land part 15 Insulating base layer 17 Bonding part 18 Void part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsutomo Nikaido 1106 Fujikubo, Miyoshi-cho, Iruma-gun, Saitama Japan CMC Co., Ltd. In the company

Claims (1)

[Claims] 1. A printed wiring board formed by printing a resistance paste between bonding lands in a printed wiring circuit by printing a resistance paste, wherein an insulating underlayer is provided between the bonding lands and a void for resistance adjustment is provided. A printed wiring board, characterized in that it is constituted by providing a portion and forming the resistance portion through the insulating underlayer and the void portion.