JPH0323577Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is applicable to a device that is inserted into a pin board of a circuit board inspection machine or a mounted board inspection machine (in-circuit inspection machine) that inspects integrated circuits (ICs), for example. The present invention relates to a contact probe used, and particularly to a contact probe with movable ends.

[Technical background of the invention]

As shown in FIG. 1, this type of contact probe that has already been proposed has a conductive and cylindrical sleeve 2 inserted into a pin board 1 in an inspection machine. A pair of plunger contact pins 3, 4 formed in the openings 2a, 2b at both ends are made slidable via a coil spring 5, and each stopper is formed by drawing on a part of the sleeve 2 to prevent them from slipping out. 6a, 6b
It is regulated and structured by

On the other hand, in the contact probe shown in FIG. 2, tapers 3a, 4a are formed at the inner ends of the plunger contact pins 3, 4, and balls 7, 8 are inserted into the taper parts 3a, 4a. The coil spring 5 is provided elastically.

Therefore, in both of the contact probes described above, contact continuity is achieved by bringing the contact portion 3b of one plunger contact pin 3 into contact with the object to be inspected, and by bringing the contact portion 4b of the other plunger contact pin 4 into contact with the power supply circuit. Then, the continuity of this test object is tested.

In this way, the above-mentioned contact probe is electrically connected through contact between the sliding portions of the plunger contact pins 3 and 4 and the inner circumferential wall of the sleeve 2. 4, there is a very small gap between the two, so there is a risk of poor contact and continuity.

Therefore, as shown in FIG. 2, in order for the sliding portions of each of the plunger contact pins 3 and 4 to effectively and appropriately contact the inner circumferential wall of the sleeve 2, the inside of each of the plunger contact pins 3 and 4 is Tapers 3a and 4a are formed at the ends so that the elastic force of the coil spring 5 is pressed through the balls 7 and 8.

[Problems with background technology]

However, in the above-mentioned contact probe, when inspecting an object to be inspected, the current from the contact portion 3b of the one plunger contact pin 3 is transferred from the sliding portion of the plunger contact pin 3 to the sleeve 2.
The power is transmitted through the sleeve 2 to the contact portion 4b of the plunger contact pin 4 at the other end of the sleeve 2, and led out to the cable through a power supply socket (not shown).

The resistance value at this time is, for example, usually about 25 to 30 m.
The impedance is approximately Ω. This current itself flows through a path that is easy to flow from the plunger contact pin 3 to the sleeve 2 to the plunger contact pin 4, and this flowing current is measured, and the loss in resistance value is substantially reduced. It's not a problem.

However, the above-mentioned contact probe may suddenly exhibit an extremely high impedance of about 3 to 4 ohms.

This is regardless of the conduction circuit of the conduction route described above, the plunger contact pin 3 - ball 7 - coil spring 5 - ball 8 - plunger contact pin 4.
This is due to the fact that the flow passes through a conduction circuit as a conduction route.

That is, since the sleeve 2 and the sliding parts of the plunger contact pins 3 and 4 are in contact with each other through slight line contact, the sliding surfaces of the sliding parts are connected to the inner surface of the sleeve 2. Since the sleeve 2 slides while being biased to a part of the circumferential surface and being pressed all the time, the contact surface of the sleeve 2 is usually damaged due to the surface roughness of each sliding part and the presence of foreign matter such as dust on the contact surface of the sleeve 2. The conduction route becomes incomplete, and as a result, a very high impedance is exhibited through the other conduction routes.

In this way, both of the above-mentioned contact probes use the sleeve 2 as the main conduction route, so if the contact between the plunger contact pins 3 and 4 and the sleeve 2 becomes unstable, smooth conduction may not be obtained. Otherwise, the contact resistance may become abnormally high. The coil spring 5, which is the cause of this high resistance value, acts to push the plunger contact pins 3 and 4 outward, so the coil spring 5 is replaced with an insulator and the high resistance value is increased. Although it is possible to prevent the resistance value from being displayed, in this case, if contaminants are present for some reason, the conduction function is completely lost and an incomplete contact state occurs, which causes the plunger contact pin 3,
4 may generate heat and burn out.

On the other hand, when the inner diameter of the sleeve 2 is about 1.0 mm and the stroke of each plunger contact pin 3, 4 is about 3 to 5 mm, the coil spring 5
The diameter of the wire must be approximately 0.12 mm, and it is difficult to convert this to an elastic material made of insulating material.
Further, even if the surface of the coil spring 5 is coated with an insulating coating, the elasticity is slightly affected and there is a problem in durability against sliding.

[Purpose of invention]

The present invention was developed in view of the above-mentioned circumstances, and consists of a pair of plunger contact pins connected by a central conductor to form an electrical bypass circuit, thereby providing stable continuity and contact for continuity testing of the test object. Some contact probes are provided which aim to ensure continuity and also improve the reliability of testing an object to be tested.

[Summary of the idea]

The present invention connects a pair of plunger contact pins at both end openings of the sleeve via a coil spring, and furthermore,
It is fitted so that it can slide freely so that it does not slip out.
The inner ends of both plunger contact pins are connected by a center conductor to form a smooth conductive circuit.

[Example of idea]

Hereinafter, the present invention will be described with reference to an illustrated embodiment.

It should be noted that the present invention will be described with the same reference numerals attached to the same constituent members as in the above-described specific example.

In FIG. 3, reference numeral 1 denotes a pin board 1 in the inspection machine, and a conductive, cylindrical sleeve 2 is inserted into the pin board 1. Both end openings 2
A and 2b have a pair of conductive plunger contact pins 3 and 4 that are slidable via an extensible coil spring 5 and are formed on a part of the sleeve 2 by drawing. Each stopper 6a,
6b so as to prevent it from slipping out. The inner ends 3c and 4c of the plunger contact pins 3 and 4 are connected by a center conductor 9 made of copper, for example, and the center conductor 9 connecting the plunger contact pins 3 and 4 is Forms a conductive circuit.

Therefore, the present invention brings the contact portion 3b of one plunger contact pin 3 into contact with the object to be inspected, and
By bringing the contact portion 4b of the other plunger contact pin 4 into contact with the power supply circuit, the current of the power supply circuit passes through the center conductor 9 to test the continuity of the object to be tested.

In this way, in the present invention, since a bypass circuit is formed by the center conductor 9, there is no fear of poor contact continuity due to foreign matter, and stable continuity testing of the object to be tested can be performed reliably.

When testing an object to be inspected, that is, when the contact portions 3b and 4b of the plunger contact pins 3 and 4 contact and conduct the object against the elasticity of the coil spring 5, the center conductor 9 Although it bends slightly together with the coil spring 5, there is no risk of affecting the electrical bypass circuit.

On the other hand, in the present invention, since the conductor passes through the bypass circuit of the center conductor 9 which has low resistance, stable conduction can be maintained for a long period of time. Further, the bypass circuit composed of the plunger contact pins 3 and 4 and the center conductor 9 has a low resistance because the specific resistance value of the center conductor 9 is only about the same as that of the center conductor 9. Since it is stretched across the sides, it can also be used for multi-contact type contact probes in which a plurality of contact elements are installed upright.

Next, in another embodiment of the present invention shown in FIG. 4, the inner ends 3c, 4c of the two plunger contact pins 3, 4 and the center conductor 9 are connected by caulking, and the above-mentioned It has the same configuration as the specific example.

[Effect of idea]

As described above, according to the present invention, the sleeve 2
A pair of plunger contact pins 3, 4 are slidably fitted into the openings 2a, 2b at both ends of the body via a coil spring 5 so as not to come off outward. Inner end 3
c and 4c are connected by the center conductor 9 to form an electrical bypass circuit, so reliable contact continuity can be stably maintained over a long period of time, and continuity testing can be performed due to the low resistance. Not only is this possible, but the structure is simple and assembly and adjustment is easy, so it is possible to save labor through mass production.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of contact probes that have already been proposed, FIG. 3 is a cross-sectional view of a contact probe according to the present invention, and FIG. 4 is a diagram showing another embodiment of the present invention. It is. 1...pin board, 2...sleeve, 3, 4...
... Plunger contact pin, 5 ... Coil spring, 6
a, 6b...stopper, 9...center conductor.

Claims (1)

[Scope of utility model registration request] Each stopper is formed in the openings at both ends of the conductive sleeve by drawing, and each conductive plunger contact pin is slidably fitted into each stopper so as not to come out outwardly, and each of the conductive plunger contact pins is slidably fitted into each of the stoppers so as not to slip out. A coil spring is interposed between each of the inner ends of the plunger contact pins to urge both of the plunger contact pins to protrude outward, and the inner end of the one plunger contact pin and the other plunger contact pin are biased to protrude outward. A contact probe characterized by connecting the inner end of a plunger contact pin with a center conductor.