JPH03261086A - Device for preventing electrostatic breakdown - Google Patents

Abstract

PURPOSE:To prevent a printed board between discharge terminals from being damaged or stained by providing an opening or recess in a nonconductive base at the cap portion of a discharge terminal conductive pattern. CONSTITUTION:When static electricity with high voltage is applied to a device from the outside via e.g. a lead wire connected to a conductive pattern 5, electric discharge occurs between the conductive pattern 5 and a discharge terminal pattern 9 formed in a ground pattern 3. By this discharge static electricity with high voltage is discharged from the conductive pattern 5 to the ground pattern 3 so that the voltage of the conductive pattern 5 is reduced. Because the voltage of the conductive pattern 5 is transmitted to an internal circuit through a resistance 17, the voltage is further reduced by the resistance 17 and the input impedance of the internal circuit, etc. Therefore static electricity with high voltage is not directly applied to the input end of the internal circuit and breakdown of the internal circuit is precisely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrostatic damage prevention device, and particularly to a device for preventing damage and contamination of a printed circuit board in the vicinity of discharge terminals formed by a conductive pattern. Regarding technology to prevent this.

[Prior Art] To prevent the internal circuits of an integrated circuit device etc. from being destroyed by static electricity, a circuit board or an input circuit in a CJ integrated circuit device is configured with a resistor, a resistor, etc. It is common practice to provide a protection circuit. However, as the number of circuits on an integrated circuit device or printed circuit board increases and the degree of integration increases, it becomes difficult to secure circuit space for such protection circuits, and the protection diodes themselves become Due to deterioration, the protection unit may no longer function.

In order to eliminate such inconveniences, conventionally, as described in Utility Model Publication No. 11408/1983,
- Forms discharge terminals on the conductive pattern of the circuit board, and when high-voltage static electricity is applied, a discharge occurs between the discharge terminals, thereby suppressing the application of high voltage to the internal circuitry. There are some known protection methods.

[Problems to be Solved by the Invention] However, in such a conventional device, when a discharge occurs due to high voltage static electricity applied between the discharge terminals, the discharge occurs between the conductive foils for the discharge terminals. The printed circuit board may be damaged or contaminated with soot or the like, changing the discharge characteristics and, in some cases, deteriorating the insulation characteristics between the discharge terminals.

SUMMARY OF THE INVENTION In view of the problems in the conventional devices described above, an object of the present invention is to provide an electrostatic damage prevention device that prevents damage and dirt on a printed circuit board between discharge terminals for preventing electrostatic damage constructed on a printed circuit board. The objective is to prevent this and maintain stable discharge characteristics.

[Means for Solving the Problems] The electrostatic damage prevention device according to the present invention includes conductive patterns for discharge terminals formed on a non-conductive substrate so as to face each other with a gap section at a predetermined interval. , an opening or depression is provided in the non-conductive substrate in the gap portion.

Further, for example, one of the conductive patterns for the discharge terminal is connected to a ground pattern, and the other is connected to an input terminal, and the input terminal is connected to an internal circuit formed on the non-conductive substrate via a resistor. can be connected to the input end of

[Function] In the above configuration, when high-voltage static electricity is applied to the conductive pattern for the discharge terminals, discharge occurs between the discharge terminals, and high voltage is prevented from being applied to the internal circuit. In this case, since the non-conductive substrate in the gap between the discharge terminals is provided with an opening or a depression, the discharge current does not flow close to the substrate surface, and the substrate near the discharge path is No more damage or contamination. Therefore, stable discharge characteristics are maintained over a long period of time.

Also, one of the conductive patterns for the discharge terminal is used as a ground pattern or connected to the ground pattern, and the other is used as the conductive pattern for the input terminal or connected to the input terminal, and the input terminal is connected to the internal circuit through a resistor. By connecting the terminals, high-voltage static electricity is trapped in the discharge between the discharge terminals and the pressure is reduced, and the pressure is further reduced by the resistor, thereby providing more appropriate protection of the internal circuit.

[Example code] Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIGS. 1(a) and 1(b) respectively show a partial plan view and a sectional view of an electrostatic breakdown prevention device according to an embodiment of the present invention. As shown in these figures, the electrostatic breakdown prevention device according to the present invention has conductive patterns 3, 5, 7, etc. formed on an insulating substrate 1. In this case, the conductive pattern 3 is, for example, a ground pattern, and the conductive patterns 5,
7 is a conductive pattern for an input terminal, for example. Lead wires of an external circuit are soldered to these conductive patterns for input terminals, and input signals are applied thereto. The portions of the ground pattern 3 facing the conductive patterns 57 each have a sharp shape to constitute a discharge terminal. However, this sharp shape may be provided in accordance with one rule of the conductive patterns 5 and 7, or it may be provided facing both the ground pattern 3 and the conductive patterns 5 and 7.

According to the present invention, depressions or recesses 13 are formed by counterboring, for example, in the insulating substrate 1 between the conductive patterns 9 and 5 and between the conductive patterns 11 and 7 constituting such a discharge terminal.
．． 15 are provided.

In addition, each conductive pattern 57 that connects the input terminal has a relatively low resistance value, for example, several tens of ohms to several hundred ohms,
It is connected to a conductive pattern 21.23 connected to an input terminal of an internal circuit (not shown) via a resistor 17.19.

The internal circuit in this case is, for example, a circuit configured by an integrated circuit device mounted on the substrate 1.

In the device shown in FIG. 1, for example, when high voltage static electricity is applied from the outside via a lead wire (not shown) connected to the conductive pattern 5, the discharge terminal pattern formed on the conductive button 5 and the ground pattern 3 9, a discharge occurs between the two. Due to this discharge, high voltage static electricity is transferred to the conductive pattern 5.
is discharged to the ground pattern 3, and the voltage of the conductive pattern 5 is reduced. In addition, since the voltage of the conductive pattern 5 passes through the resistor 17 when being transmitted to the internal circuit (not shown),
The pressure is further reduced by this resistance and the input impedance of the internal circuit. Therefore, high-voltage static electricity is not directly applied to the input terminal of the internal circuit, and damage to the internal circuit is accurately prevented.

When such a discharge occurs, since a recess 13 is provided in the substrate 1 in the gap between the conductive patterns 9 and 5 constituting the discharge terminal by counterbore processing or the like, the discharge occurs between the conductive patterns 9 and 5. This is done via the space between 5. Therefore, the discharge path is no longer close to the surface of the substrate 1, and the substrate 1 is not burned or damaged by the discharge current, or the substrate is not contaminated by soot or the like. Therefore, the conductive patterns 9 and 5 forming the discharge terminal
The state of the discharge path between the
Stable discharge characteristics are always maintained.

FIG. 2 is a sectional view taken along the line A--A in FIG. 1 of an electrostatic breakdown prevention device according to another embodiment of the present invention. In the device of FIG. 2, the recess 13 in the device of FIG. 1(b)
Instead, a through hole 2 is provided in the substrate 1 at the discharge gap portion.
5 are provided.

Even in this configuration, if a discharge occurs between the conductive patterns 9 and 5 that constitute the discharge terminal, damage or contamination of the board surface will not occur, as in the case of Fig. 1 (b). It is.

In addition, when the gap width between the discharge terminals in the above-mentioned electrostatic damage prevention device is set to about 0.5 mm, for example, the discharge starting voltage will be about several 10 oV or less. As a result, even if, for example, static electricity with a voltage of several tens of kilovolts is applied to the input terminal, the voltage between the discharge terminals is reduced to several hundred volts or less. Furthermore, the voltage applied to the input terminal of the actual internal circuit is further attenuated by the resistor connected in series with the input terminal.

[Effect of the invention] As described above, according to the present invention, the extremely simple 'lf4
The structure prevents damage and contamination of the board between the discharge terminals,
Furthermore, contamination of the discharge terminal itself is also prevented. Therefore, stable discharge conditions are maintained over a long period of time, and internal circuits are properly protected.

17.19: Resistance, 21.23: Input end conductive pattern, 25: Penetration opening.

[Brief explanation of drawings]

FIG. 1(a) is a partial plan view showing an electrostatic breakdown prevention device according to an embodiment of the present invention, and FIG. 1(b) is a sectional view taken along line A-A in FIG. 1(a). , and FIG. 2 are partial cross-sectional views showing an electrostatic breakdown prevention device according to another embodiment of the present invention. 1: Non-conductive substrate, 3 Nigerland pattern, 5.7 Conductive pattern for two-person terminal, 911: Pattern for discharge terminal, 13 15: < recessed part,

Claims (2)

[Claims] 1. An electrostatic breakdown prevention device comprising a non-conductive substrate and a conductive pattern for a discharge terminal formed on the non-conductive substrate to face each other with a gap at a predetermined interval, An electrostatic damage prevention device characterized by having an opening or a depression in a conductive substrate. 2. One of the conductive patterns for the discharge terminal is connected to a ground pattern formed on the non-conductive substrate, and the other is connected to an input terminal, which is formed on the non-conductive substrate via a resistor. The electrostatic damage prevention device according to claim 1, wherein the electrostatic damage prevention device is connected to an input terminal of an internal circuit.