JPH10215039A - Wiring substrate for electronic circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring substrate for an electronic circuit capable of preventing, in any electronic circuit, large current generation caused by migration, and superior to high degree of freedom in a design of substrate. SOLUTION: A wiring substrate 10 has a plus-side pattern 11 and a minus-side pattern 12, and an auxiliary wiring pattern 13 between the pattern 11 and the pattern 12. The auxiliary wiring pattern 13 is wired far from the plus-side pattern 11 and closer to the minus-side pattern 12. The auxiliary wiring pattern 13 is connected to the plus-side pattern 11 through a resistor 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wiring board,
More specifically, the present invention relates to a wiring board for an electronic circuit in which a wiring short circuit due to migration is taken.

[0002]

2. Description of the Related Art Conventionally, various proposals have been made to take measures to prevent migration of an electronic circuit wiring board and to take measures to reduce the influence of migration.
For example, one described in Japanese Unexamined Patent Application Publication No. 6-85166, "Circuit Board and Electrical Equipment Equipped With It" is known.

This publication discloses a thin film resistor pattern as shown in FIG. 10 which can prevent a change in circuit characteristics due to migration. In FIG. 10, the thin-film resistance pattern 101 has a high-precision resistance between the electrodes A and B, and the electrode A is on the high potential side. In the thin-film resistance pattern 101, a conductive portion 102 is provided inside a broken line in the drawing where migration is likely to occur due to a potential difference. This conductive portion 102 has substantially the same potential as the electrode A,
Thin-film resistance pattern 1 facing away from conductive portion 102
Migration occurs in the low potential pattern portion 101a of No. 01.

For this reason, cations ionized by a high electric field generated between the low potential pattern portion 101a and the low potential pattern portion 101a which are close to and separated from each other are deposited on an edge portion 102a of the conductive portion 102 on the low potential pattern portion 101a side. The resistance value of the conductive part 102 changes. That is, the conductive part 102 is the same as the conductive part 1.
The high potential thin film resistance pattern portion 101b located on the left side in FIG. 02 is protected from the influence of migration, and the quality of the thin film resistance pattern 101 is improved.

[0005]

By the way, the above-mentioned conventional conductive portion 102 for protecting the migration includes at least one of the portions for protecting the migration, that is, the low potential pattern portion 101a and the high potential pattern portion 101b. Was required to be a resistance pattern. Therefore, in the above-mentioned conventional migration protection structure, the applicable range is naturally limited.

The conductive portion 102 is formed directly connected to the high potential pattern portion 101b for protecting migration. Therefore, when the conductive portion 102 and the low-potential pattern portion 101a are short-circuited due to the growth of migration, it is inevitable that the low-potential pattern portion 101a and the high-potential pattern portion 101b short-circuit. Therefore, in an extreme case, a large current flows due to a short circuit, the wiring pattern is melted, and the heat generated at that time may cause inconvenience such as carbonization of the wiring board.

On the other hand, as an electronic circuit wiring board used for a power supply circuit, those shown in FIGS. 11 and 12 are generally known. This power supply circuit 210a is configured as shown in FIG.
12 and an equivalent circuit diagram of FIG. 12, a storage battery 216, a wiring board 210 (not shown in FIG. 12), a backflow prevention diode 217, voltage stabilizing ICs 218 and I
It comprises a Zener diode 219 for C protection and the like. The voltage stabilizing IC 218 is provided with capacitors 218a and 218b for improving reliability.

In such a power supply circuit 210a,
Generally, the internal resistance of the storage battery 216 is low. Therefore, a migration 220 occurs between the plus side pattern 211 and the minus side pattern 212 on the side of the storage battery 216 from the voltage stabilization IC 218, and the migration 220 grows, and the plus side pattern 211 and the minus side pattern 21
When 2 is short-circuited, a large current flows. As a result, carbonization or the like occurs in the wiring board 210 as described above,
0 is less reliable.

Therefore, in such a wiring board 210, both the patterns 211 and 212 must be largely separated from each other so that the plus side pattern 211 and the minus side pattern 212 do not short-circuit even if the migration 220 occurs. Did not get. As a result, the wiring board 2
For example, an extra space is required on the substrate 10, and the degree of freedom in designing a substrate is significantly impaired.

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent generation of a large current due to migration in any electronic circuit, and to improve the substrate design. Another object of the present invention is to provide an electronic circuit wiring board having a high degree of freedom.

[0011]

According to one aspect of the present invention, there is provided an electronic circuit wiring board having a high-potential wiring pattern and a low-potential wiring pattern. The gist is that an auxiliary wiring pattern connected to the high-potential wiring pattern via an electric resistor is provided between the potential wiring pattern and the low-potential wiring pattern.

According to the above configuration, migration occurs between the auxiliary wiring pattern and the low-potential wiring pattern,
Even if both patterns are short-circuited, the current flows through the electric resistance, and a large current does not flow. In addition, by appropriately setting the electric resistance value, it is possible to blow out the site bonded by migration.

According to a second aspect of the present invention, in the electronic circuit wiring board according to the first aspect, at least the auxiliary wiring pattern is provided as an exposed wiring pattern having no protective coating layer. And

According to the above configuration, the migration that grows from the low-potential wiring pattern more reliably reaches the auxiliary wiring pattern.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a substrate structure when the wiring substrate according to the present embodiment is applied to the power supply circuit shown in FIG. 11, and FIG. 2 shows an equivalent circuit thereof. As shown in FIG. 1 and FIG.
a has a plus side pattern 11 and a minus side pattern 12 on a substrate 10 (not shown in FIG. 2);
An auxiliary wiring pattern 13 is provided between the pattern 1 and the pattern 12. The auxiliary wiring pattern 13 is wired so as to be separated from the plus side pattern 11 and closer to the minus side pattern 12 side. Further, the auxiliary wiring pattern 13 is connected to the positive side pattern 1 via a resistor 14.
1 and is electrically connected.

The positive pattern 11 is electrically connected to the positive electrode of the storage battery 16 via the terminal 15a of the connector 15. Similarly, the negative side pattern 12
Is electrically connected to the negative electrode of the storage battery 16 via the terminal 15b of the connector 15.

The plus side pattern 11 is provided with a backflow prevention diode 17 and a voltage stabilizing IC 18. Further, the voltage stabilizing IC 18 is provided with capacitors 18a and 18b for improving reliability and a zener diode 19 for input voltage protection.

The surface of the substrate 10, including the patterns 11, 12 and the auxiliary wiring pattern 13, is protected as shown in the sectional view of FIG. 3 (a sectional view taken along the line III-III in FIG. 1). It is covered with a coating material 21.

Next, the operation of the substrate 10 in the present embodiment will be described. In the board 10, the connector 15
The power of the storage battery 16 is supplied to the substrate 10 via the power supply. The voltage of the storage battery 16 is converted to a predetermined voltage by the voltage stabilizing IC 18 and stabilized, and is applied to an electronic component (not shown).

At this time, as described above, the potential difference between the plus side pattern 11 and the minus side
The migration 20 may occur due to the upper moisture and the electrolyte contained in the protective coating material 21. In this case, the migration 20 grows from the minus pattern 12 to the plus pattern 11. When the growth reaches the auxiliary wiring pattern 13, a constant current flows from the plus side pattern 11 to the minus side pattern 12 via the resistor 14. At this time, if the line of the migration 20 is thin, the line of the migration 20 is cut off by heat due to the current. Since the auxiliary wiring pattern 13 and the positive pattern 11 have the same potential, no migration 20 occurs between the auxiliary wiring pattern 13 and the positive pattern 11.

As described above, according to the wiring board of the present embodiment, the following effects can be obtained.
That is, according to the substrate 10 of the present embodiment, the short circuit between the plus side pattern 11 and the minus side pattern 12 due to the migration 20 is prevented by the auxiliary wiring pattern 13. For this reason, conventionally, it was necessary to separate the plus side pattern 11 and the minus side pattern 12 for wiring, but the separation distance can be greatly reduced, and the degree of freedom in designing the wiring pattern can be suitably increased. . As a result, the size of the substrate 10 can be reduced, and the manufacturing cost of the substrate 10 can be reduced.

[Second Embodiment] Next, a second embodiment of the present invention will be described, focusing on differences from the first embodiment. In the description of the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 4 shows a schematic configuration of a wiring board according to the present embodiment, similarly to FIG. In the first embodiment, if the protective coating 21 on the positive side pattern 11 has a hole due to a coating error or the like, the migration 20 that has grown inside the protective coating 21 is directly positive. There is a concern that the side pattern 11 will be reached. Therefore, in the present embodiment, the protective coating material in the region 22 shown by hatching in FIG. 4, that is, the region on and in the vicinity of the auxiliary wiring pattern 13 is removed.

Next, the operation and effect of the wiring board in this embodiment will be described. In the present embodiment, FIG.
As shown in the cross-sectional view of FIG. 5 (the cross-sectional view along the line VV in FIG. 4), the region 22 indicated by hatching in FIG.
Has been removed. Therefore, the migration 2
When 0 (see FIG. 1) grows from the minus side pattern 12 to the plus side pattern 11 along the surface of the protective coating material 21, it reaches the plus side pattern 11 directly without being combined with the auxiliary wiring pattern 13. Is suitably prevented. That is, the minus side pattern 12
In the present embodiment, the migration 20 that grows toward the plus-side pattern 11 is securely coupled to the auxiliary wiring pattern 13 and does not directly reach the plus-side pattern 11.

The present invention can be embodied with the following modifications. (B) In each of the above embodiments, an example of the power supply circuit for stabilizing the storage battery voltage is shown. However, the present invention is not limited to this, and the present invention uses a high potential wiring pattern and a low potential wiring pattern. The present invention can be applied to any electronic circuit wiring board in which a short circuit due to migration is concerned. For example, a large-output DC power supply circuit board, a high-output amplifier circuit board, a high-voltage DC power supply circuit board, and the like can be given.

(B) In each of the above embodiments, an example is shown in which the auxiliary wiring pattern 13 provided on the plus side pattern 11 via the resistor 14 is a single continuous pattern. However, the present invention is not limited to this. Instead, a plurality of auxiliary wiring patterns may be provided. For example, as shown in FIG.
A configuration in which a further auxiliary wiring pattern 13a is provided separately from the auxiliary wiring pattern 13 on the plus side pattern 11 via a resistor 14a may be adopted.

(C) In each of the above embodiments, the configuration in which the auxiliary wiring pattern 13 is not connected to the connector 15 is shown. However, as shown in FIG. 7, the configuration may be such that the auxiliary wiring pattern 13 is connected to the connector terminal 15c. According to this configuration, the connector terminals 15a (connection terminals of the plus side pattern 11) and 1
Short circuit due to migration occurring between 5b (connection terminal of the minus side pattern 12) is also suitably prevented.

(D) In the above embodiments, the resistor 14 is a fixed resistor. However, the present invention is not limited to this, and a variable resistor may be used. According to this configuration, it is possible to easily adjust the current flowing through the auxiliary wiring pattern 13, and it is also possible to timely actively melt the part connected by the migration.

(E) In the second embodiment, the configuration is shown in which the protective coating material is removed on the auxiliary wiring pattern 13 and the area in the vicinity of the auxiliary wiring pattern 13. However, the hatched area (the auxiliary wiring pattern 13) in FIG. , Minus side pattern 12
It is also possible to adopt a configuration in which the protective coating material of the upper region 22a and the vicinity thereof is removed. FIG. 9 shows a cross-sectional view (a cross-sectional view along line IX-IX of FIG. 8).

According to this configuration, the auxiliary wiring pattern 13
And the growth of the migration between the negative side pattern 12 and the negative side pattern 12 can be further ensured. In addition, the area 2
The water and the like adhering to the 2a due to dew condensation or the like can be removed at an early stage by electrolysis with a constant current.

Further, the technical idea grasped by the above embodiment will be described below. (1) The wiring board for an electronic circuit according to claim 1 or 2, wherein the auxiliary wiring pattern and the low-potential wiring pattern are arranged close to each other.

According to this configuration, it is possible to further ensure the migration growth between the auxiliary wiring pattern and the low-potential wiring pattern. Therefore, migration growth between the high-potential wiring pattern and the low-potential wiring pattern is reliably prevented.

(2) In the electronic circuit wiring board according to claim 1 or (1), at least both the auxiliary wiring pattern and the low potential wiring pattern are provided as exposed wiring patterns having no protective coating layer. A wiring substrate for an electronic circuit, characterized in that:

According to this configuration, migration growth between the auxiliary wiring pattern and the low-potential wiring pattern can be further ensured.

[0036]

According to the first aspect of the present invention, the migration occurs between the auxiliary wiring pattern and the low-potential wiring pattern, and even if both the patterns are short-circuited, the current flows through the electric resistance, No large current flows.
In addition, by appropriately setting the electric resistance value, it is possible to melt the bonded portion by migration.

Further, the present invention is a very simple method of simply adding an auxiliary wiring pattern and an electric resistance to any electronic circuit wiring substrate having a high-potential wiring pattern and a low-potential wiring pattern and in which a short circuit due to migration is likely to occur. Can be applied in any way.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the removal of the protective coating layer on the auxiliary wiring pattern makes migration growing from the low potential wiring pattern more effective. It will surely reach the auxiliary wiring pattern.

[Brief description of the drawings]

FIG. 1 is a schematic partial plan view showing a first embodiment of an electronic circuit wiring board embodying the present invention.

FIG. 2 is an equivalent circuit diagram of the same.

FIG. 3 is a sectional view taken along the line III-III in FIG. 1;

FIG. 4 is a schematic partial plan view showing a second embodiment.

FIG. 5 is a sectional view taken along the line VV.

FIG. 6 is a schematic partial plan view showing another embodiment.

FIG. 7 is a schematic partial plan view showing another embodiment.

FIG. 8 is a schematic partial plan view showing another embodiment.

FIG. 9 is a sectional view taken along the line IX-IX.

FIG. 10 is a plan view showing a thin-film resistance pattern on a conventional wiring board.

FIG. 11 is a schematic partial plan view showing a conventional power supply circuit example.

FIG. 12 is an equivalent circuit diagram of the same.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... wiring board, 10a ... power supply circuit, 11 ... plus side pattern (high potential wiring pattern), 12 ... minus side pattern (low potential wiring pattern), 13 ... auxiliary wiring pattern, 14 ... resistor, 21 ... protective coating material.

Claims (2)

[Claims] 1. An electronic circuit wiring board comprising a high-potential wiring pattern and a low-potential wiring pattern, wherein said high-potential wiring pattern and said electric potential are provided between said high-potential wiring pattern and said low-potential wiring pattern. An electronic circuit wiring board, comprising an auxiliary wiring pattern connected via a resistor. 2. The wiring board for an electronic circuit according to claim 1, wherein at least the auxiliary wiring pattern is provided as an exposed wiring pattern having no protective coating layer.