JPH0964531A - Solder bridge removing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove fine solder bridges which can not be found easily through visual inspection by connecting the output from a constant voltage power supply between two arbitrary points of a circuit system where a solder bridge is present and then applying an appropriate voltage thereby fusing the solder bridge with Joule's heat generated at the solder bridge. SOLUTION: Output from a constant voltage power supply 1 is connected with an appropriate part of a circuit system where a solder bridge is present using clips, for example, and then an appropriate voltage is applied thereto. Since the resistance 2 of a copper foil pattern is sufficiently lower than the resistance 4 of a solder bridge which is sufficiently lower than the original resistance 3 of circuit, the current I is determined by the resistance 4 of the solder bridge and the solder bridge is fused and removed immediately when the temperature is raised by Joule's heat and exceeds the melting point of solder. Since visual detection of solder bridge is not required, the manpower can be saved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection of a printed wiring board after component mounting, and more particularly to a technique for removing a solder bridge detected by a short check.

[0002]

2. Description of the Related Art In recent years, the density of printed wiring boards used in electronic devices has been increasing, and the components to be mounted are generally surface mount type (hereinafter referred to as SMD). On the other hand, miniaturization of SMD components to be mounted has also progressed, and a solder bridge (short between two points) is likely to occur during soldering. When applied to an in-circuit tester or the like, if the printed wiring board has a solder bridge, the circuit system can be easily detected, but it cannot be detected in which part of the circuit system the solder bridge actually occurs.

[0003]

Conventionally, when such a solder bridge is generated, it is general to perform a visual inspection with a microscope, but it is densified and the parts are arranged in a complicated manner. The drawback was that it was difficult to inspect the points and could not be found. Also, if a solder bridge is generated on the printed wiring board, it cannot be incorporated into the device unless it is found and removed, expensive electronic parts are mounted, and it was time-consuming to manufacture. There was also a drawback that the printed wiring board had to be discarded.
The present invention has been made to solve the above problems,
An object of the present invention is to provide a solder bridge removing device that removes a minute solder bridge that cannot be easily found by visual inspection by Joule heat.

[0004]

SUMMARY OF THE INVENTION The present invention is a constant voltage power supply capable of setting a current and a voltage between any two points in a circuit system where a solder bridge is generated in removing a fine solder bridge of a printed wiring board. Is connected by a connecting means, an appropriate voltage suitable for the circuit system is applied, and the solder bridge is melted by Joule heat generated by the solder bridge to remove the solder bridge.

[0005]

According to the present invention, since it is decided to apply an appropriate voltage according to the circuit system between any two points of the circuit system where the solder bridge is generated, Joule heat is generated by this solder bridge. And melt the solder bridge.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a conceptual diagram for explaining the operation of a solder bridge removing device showing an embodiment of the present invention. In FIG. 1, 1 is a solder bridge removing device,
Constant voltage power source that can set current and voltage to supply energy to remove solder bridge, 2 is resistance of copper foil pattern between two points of circuit system where solder bridge is generated, 3 is solder bridge generation The resistance originally possessed by the circuit between the two points of the existing circuit system, 4 is the resistance possessed by the solder bridge.

The operation of such a solder bridge removing device will be described with reference to FIG. Check the allowable voltage and polarity of the circuit system in which the solder bridge is generated, and use an output of the constant voltage power supply 1 such as a clip to locate an appropriate portion of the circuit system in which the solder bridge is easily pinched. They are connected by being sandwiched and an appropriate voltage is applied. The resistance 2 of the copper foil pattern is sufficiently smaller than the resistance 4 of the solder bridge, and the resistance 4 of the solder bridge is sufficiently smaller than the resistance 3 of the circuit. Therefore, the flowing current I is the resistance 4 of the solder bridge. It is determined. Assuming that the time during which the current I is flowing is t and the resistance value of the resistor 4 of the solder bridge is R, the Joule heat Q generated in the resistor 4 of the solder bridge is generated.
Is as follows. Q = I2 × R3 × t (joule) The temperature of this solder bridge rises due to this Joule heat, and at the moment when it exceeds the melting point of the solder (about 183 degrees Celsius), this solder bridge melts and this solder bridge is removed. To be done. Experimentally, the melting time of this solder bridge did not exceed 1 second, but it is desirable to limit the application time by a timer so that the voltage is not unnecessarily applied.

[0008]

According to the present invention, as described above,
Between any two points of the circuit system where the solder bridge is generated,
Appropriate voltage suitable for the circuit system is applied, Joule heat is generated according to the resistance value of the solder bridge, and the solder bridge is melted. In addition, since it is not necessary to discard the originally usable printed wiring board, it is possible to contribute to resource saving and reduce cost.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a solder bridge removing device showing an embodiment of the present invention.

[Explanation of symbols]

1 constant voltage power supply 2 resistance of the copper foil pattern of the circuit between the two points of the circuit system where the solder bridge is generated 3 resistance originally possessed by the circuit between the two points of the circuit system where the solder bridge is generated 4 solder bridge Resistance of

Claims (1)

[Claims] 1. When removing a fine solder bridge of a printed wiring board, the output of a constant voltage power source capable of setting a current and a voltage is connected to any two points of a circuit system where the solder bridge is generated by connecting means. Then, an appropriate voltage suitable for the circuit system is applied, and the solder bridge is removed by the Joule heat generated by the solder bridge, and the solder bridge is removed.