JPH08107256A - Printed-wiring substrate - Google Patents

Abstract

PURPOSE: To lower the discharge starting voltage of the lightning surge energy by making an aperture parts in the substrate part between a pair of electrode patterns for shortening the interval between both electrode patterns. CONSTITUTION: The printed-wiring substrate having a pair of electrode patterns 15A, 15B for the lightning surge counter measure is composed to discharge the lightning surge energy arranged at a specific interval G on a substrate 11. On the other hand, a slit 12 is formed as an aperture part between the substrate 11 part between the pair of electrode patterns 15A, 15B for shortening the interval G between both electrode patterns 15A, 15B. Furthermore, the slit 12 is aperture-formed to be extended in the width direction of the electrode patterns 15A, 15B while the length L1 of the slit 12 is formed at a specific distance longer than the width dimension L of the electrode patterns 15A, 15B. Through these procedure, the restriction on the safety standard of both electrode patterns 15A, 15B to the interval G can be changed from the creeping distance to the spatial distance, thereby enabling the interval G to be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board having an electrode pattern for lightning surge protection.

[0002]

2. Description of the Related Art FIGS. 2A and 2B are views showing a conventional structure of a printed wiring board, in which FIG.
It is sectional drawing by -X. In the figure, 11 is a substrate, 1
4A and 14B are print patterns, and 19 is a solder resist. The substrate 11 is made of epoxy resin or the like. In addition, usually, the print pattern (14A, 14
B) is formed of copper foil, and elements (transistors, capacitors, resistors, etc.) are soldered thereto.

When a lightning surge enters the printed wiring board having the above-described structure, an excessive surge current may flow through the printed pattern 14 even though it is instantaneous, and the element may be damaged.

Therefore, conventionally, the print pattern (1
4A, 14B), a pair of electrode patterns (15A, 15) for lightning surge countermeasures, which are opposed to each other with a predetermined distance (G).
B) is formed, and the electric energy of the lightning surge is discharged through both electrode patterns (15A, 15B).

[0005]

By the way, in the conventional printed wiring board having the above-mentioned structure, both electrode patterns (15
The discharge start voltage changes depending on the size of the interval G of (A, 15B). That is, both electrode patterns (15A, 1
If the interval G of 5B) is increased, the discharge start voltage increases, and if the interval G is decreased, the discharge start voltage decreases.

Here, the lower the discharge start voltage is,
Although the element is less likely to be damaged by lightning surge, both electrode patterns (15A, 15A,
There is a restriction that the interval G of 15B) cannot be less than the specified interval (minimum creepage distance), and there is a limit to lowering the discharge start voltage.

In view of the above circumstances, an object of the present invention is to provide a printed wiring board capable of reducing the discharge start voltage of lightning surge energy by further shortening the interval between both electrode patterns for lightning surge countermeasures. is there.

[0008]

A printed wiring board according to the present invention has a pair of electrode patterns for lightning surge countermeasures, which are arranged facing each other at a predetermined distance on the substrate, and lightning surge energy is provided through both electrode patterns. In the printed wiring board configured to discharge the electrode, the substrate portion between the pair of electrode patterns is opened to form a slit, and the gap between the two electrode patterns is shortened.

[0009]

In the present invention having the above-mentioned structure, since the board portion between the pair of lightning surge countermeasure electrode patterns is opened and the slit is formed, the safety standard can be restricted from the creepage distance to the spatial distance.

Here, the specified interval (minimum clearance) related to the spatial distance is smaller than the specified interval (minimum creepage distance) related to the creepage distance. For example, safety standards (U
L1950), if the input voltage is 125V AC or less,
The minimum creepage distance is 1.5 mm, but the minimum clearance is 1
mm.

Therefore, the difference between the specified intervals (1.5
The discharge start voltage of lightning surge energy can be lowered by a predetermined value (about 500 V) by reducing the interval between both electrode patterns by −1 = 0.5 mm).

[0012]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 (A) and 1 (B), this printed wiring board has the same basic configuration as the conventional example [FIGS. 2 (A) and 2 (B)], but a pair of electrodes for lightning surge countermeasures. Slits 12 are formed in the portion of the substrate 11 between the patterns (15A, 15B), and the gap G between both electrode patterns (15A, 15B) is made smaller than in the conventional example. The same components as those in the conventional example [FIGS. 2A and 2B] are designated by the same reference numerals, and the description thereof will be simplified or omitted. Further, FIG. 1A is a plan view, and FIG. 1B is a line X of arrow in FIG.
It is sectional drawing by -X.

The slit 12, which is a feature of this printed wiring board, is the substrate 1 between both electrode patterns (15A, 15B).
An opening is formed in one portion so as to extend in the width direction of the electrode pattern (15A, 15B). The length L1 of the slit 12 is formed longer than the width L of the electrode pattern (15A, 15B) by a predetermined distance.

With this structure, both electrode patterns (15
A, 15B) safety standard for distance G (UL195
The constraint 0) can be changed from creepage distance to clearance.

According to the safety standard (UL1950), the input voltage A
In the case of C125V or less, the minimum creepage distance is 1.5 mm, but the minimum spatial distance is 1 mm.

Therefore, the difference of the above specified distance (1.5
-1 = 0.5 mm), both electrode patterns (15A, 1
The interval G in 5B) can be reduced.

Here, the discharge start voltage of the lightning surge energy is reduced by about 1 KV when the distance G between the electrode patterns (15A, 15B) is reduced by 1 mm. Therefore, in this embodiment, the discharge start voltage is reduced by about 500 V. can do.

According to this embodiment, however, the slit 12 is formed by opening the substrate 11 portion between the pair of electrode patterns (15A, 15B), and the two electrode patterns (15) are formed.
Since the gap G between (A, 15B) is shortened, it is possible to significantly reduce the discharge start voltage for discharging the lightning surge energy through both electrode patterns (15A, 15B). Therefore, element damage due to lightning surge energy can be prevented more effectively than in the conventional case.

[0019]

According to the present invention, the substrate portion between the pair of electrode patterns is opened to form a slit, and the gap between the two electrode patterns is shortened. Therefore, the lightning surge energy is transmitted through both electrode patterns. It is possible to greatly reduce the discharge start voltage for discharging. Therefore, element damage due to lightning surge energy can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an example of the present invention.

FIG. 2 is a diagram for explaining a conventional configuration of a printed wiring board.

[Explanation of symbols]

 11 substrate 12 slit 15A, 15B electrode pattern

Claims (1)

[Claims] 1. A printed wiring board having a pair of electrode patterns for lightning surge countermeasures, which are opposed to each other at a predetermined distance on a substrate, and is configured to discharge lightning surge energy through both electrode patterns, A printed wiring board, characterized in that a board portion between the pair of electrode patterns is opened to form a slit to reduce a gap between the two electrode patterns.