JPH057580Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is arranged in large numbers in the inspection section of a circuit board inspection device, and is brought into contact with the inspection points of the circuit board to be inspected to perform continuity testing of these inspection points. The present invention relates to contact probes for such purposes.

(Prior Art) An example of a conventional contact probe is shown in FIG. FIG. 3 is a longitudinal sectional view of an example of a conventional contact probe.

In Fig. 3, a mounting pin board 1 made of insulating resin has a large number of through holes drilled in a matrix at a pitch of several mm, and a metal cylindrical socket 2 is press-fitted into each of these through holes. . This socket 2 has an open front end, an enlarged portion 2a as a press-fitting allowance formed in the middle, and a constricted portion 2b and a lead wire connection portion 2c formed at the rear end. The contact probe 3 inserted through the opening of the socket 2 is prevented from coming off backward by the constricted portion 2b. Further, a lead wire is directly soldered to the lead wire connecting portion 2c, or a terminal to which a lead wire is soldered is fitted and connected. The contact probe 3 is slidably arranged so that the plunger 5 protrudes the contact needle 5a into the front end opening of a metal cylindrical tube 4 that is fitted and inserted into the socket 3 and does not come out. Further, the plunger 5 is elastically biased forward by a coil spring 6.

The configuration of the conventional contact probe 3 will be explained in more detail. The rear portion of the plunger 5 is formed with a tube sliding contact portion 5b having an outer diameter that is slidably fitted to the inner periphery of the tube 4, and the front portion thereof is formed with a contact needle 5a having a smaller diameter than this tube sliding contact portion 5b. There is. A V-groove having an opening of 60 degrees is formed at the tip of the contact needle 5a. In addition, tube 4
The opening at the rear end is narrowed by caulking or the like. Then, the metal sphere 7 is inserted through the opening of the tube 4, the coil spring 6 is inserted next, and the tube sliding contact portion 5 of the plunger 5 is inserted.
b is inserted. When the coil spring 6 is compressed, the opening of the tube 4 is narrowed, the contact needle 5a projects from the tube 4, and the plunger 5 is slidably disposed to form the contact probe 3. The outer periphery of the plunger 5, the inner periphery and outer periphery of the tube 4, and the inner periphery of the socket 2 are plated with a highly conductive metal such as gold or silver. Then, the tube sliding contact portion 5b slides into contact with the inner periphery of the tube 4 to establish electrical continuity between the tube 4 and the plunger 5. Also, by fitting and inserting the tube 4 into the socket 2, the tube 4 is brought into contact with the inner periphery of the socket 2. The socket 2 and tube 4 are electrically connected to each other by abutting their outer peripheries.

In this configuration, when the tip of the contact needle 5a of the plunger 5 comes into contact with a test point on the circuit board to be tested, the plunger 5 retreats within the tube 4 against the elasticity of the coil spring 6 and comes into elastic contact with the test point. . The test point is electrically connected to the tester through the plunger 5, the tube 4, and the socket 2 in series, and through a lead wire connected to the lead wire connection portion 2c of the socket 2.

(Problem to be solved by the invention) In recent years, as the number of inspection points on circuit boards to be inspected has become denser, the pitch at which the contact probes 3 are arranged on the contact pin board 1 has become smaller, for example, 2.5 mm. It is becoming. The mounting pin board 1 is relatively thick at about 20 to 30 mm, and in order to prevent a large number of through holes from connecting with each other, the maximum inner diameter of the through holes is about 1.7 mm. Therefore, if the outer diameter of the socket 2 that is press-fitted into this 1.7 mm inner diameter through hole is 1.7 mm, and the wall thickness of this socket 2 is 0.165 mm, then the outer diameter of the tube 4 of the contact probe 3 to be inserted will be 1.7 mm. The diameter is only 1.37mm.
If the wall thickness of tube 4 is 0.185 mm, the inner diameter is only 1.0 mm. Furthermore, this tube 4
Since the front end opening of the plunger 5 is narrowed, the outer diameter of the contact needle 5a of the plunger 5 is only about 0.75 mm. The coil spring 6 compressed inside the tube 4 is made of a wire rod with a wire diameter of 0.18 mm and has a coil outer diameter of 0.18 mm.
Formed to 1.0mm or less.

The conventional contact probe 3 having the above structure has the following problems.

First, in order for the plunger 5 to have a predetermined stroke, the contact needle 5 protruding from the tube 4 must be
a must have a length equal to or longer than a predetermined stroke, the contact needle 5a becomes longer depending on the stroke, and has a small outer diameter of 0.75 mm, so it has weak mechanical strength and is easily bent. In particular, when the electronic component is brought into contact with the inspection point of the circuit board to be tested on which the electronic component is mounted, it is subjected to a lateral component force due to contact with a diagonal surface such as a solder bulge or the leg of the electronic component. Easy to bend.

Further, the plunger 5 is supported by the tube sliding contact portion 5b inserted into the tube 4, but a very small gap is required between it and the inner periphery of the tube 4 in order to slide. The deviation from the axis of the tube 4 due to this gap is caused by the tube sliding contact portion 5
Although the length of the contact needle 5b is limited by the length of the contact needle 5b, the dislocation is magnified at the tip of the contact needle 5b, and the contact needle 5b is likely to be deviated from the inspection point on the circuit board to be inspected.

Furthermore, although electrical continuity between the plunger 5 and the tube 4 is performed at the tube sliding contact portion 5b,
Continuity is likely to be inhibited by flux, dust, etc. entering between the tube 4 and the tube sliding contact portion 5b, resulting in a lack of reliability.

The purpose of this invention is to
This was created to solve the problem with probes.
It is an object of the present invention to provide a contact probe whose plunger has strong mechanical strength and whose electrical continuity can be reliably obtained.

(Means for solving the problem) In order to achieve the above object, the contact probe of the present invention is a contact probe inserted into a cylindrical socket with an open front end disposed on a mounting pin board. In the plunger, a socket sliding portion is formed in the intermediate portion of the plunger to be in sliding contact with the inner periphery of the socket, a small diameter portion is formed in the rear intermediate portion of the socket sliding portion, and a diameter smaller than the small diameter portion is formed at the rear end. Forms a large tube sliding contact area,
The sliding contact portion of the tube is slidably disposed in the front end opening of a tube shorter than the socket to be fitted into and inserted into the socket so as not to slip out forward, and the rear end of the sliding contact portion of the tube inside the tube is provided. A coil spring is compressed between the tube and the rear end of the tube.

(Function) A socket sliding contact part is formed in the middle part of the plunger to make sliding contact with the inner periphery of the socket, and a tube sliding contact part is formed at the rear end, and the front end opening of the tube which is shorter than the socket to be inserted into the socket is formed. The tube sliding contact part of the plunger is arranged to be able to slide freely so as not to slip out forward, and the plunger is elastically biased forward by a coil spring compressed within the tube to form a contact probe. The front part of the plunger can be made the inner diameter of the socket, and the contact needle can be made thicker than the plunger of a conventional contact probe of this type, and its mechanical strength can be increased. In addition, electrical continuity is established between the test point where the tip of the contact needle comes into contact with the socket through two routes: one from the sliding contact part of the plunger's socket to the socket, and the other from the sliding part of the tube of the plunger to the tube and socket. The reliability of the test is high. Furthermore, since the plunger is slidably supported at two places, the socket sliding contact part and the tube sliding contact part, the deviation from the axis is reduced.
It can accurately contact the inspection point of the circuit board to be inspected.

(Description of Embodiments) Hereinafter, embodiments of the present invention will be described with reference to FIG. FIG. 1 is a longitudinal sectional view of an embodiment of the contact probe of the present invention. In Figure 1,
Components that are the same as those in FIG. 3 are given the same reference numerals and redundant explanations will be omitted.

In FIG. 1, the metal plunger 15 of the contact probe 13 has a socket sliding portion 15c with an outer diameter that slides on the inner periphery of the socket 2 at its middle portion.
A contact needle 15a having the same outer diameter is formed in the front portion of this socket sliding contact portion 15c.
A V-groove with an opening of 60 degrees is formed at the tip of the contact needle 15a. Further, a small diameter portion 15d having a smaller outer diameter than the socket sliding contact portion 15c is formed at the rear intermediate portion of the plunger 15, and a tube sliding contact portion 15b having a larger outer diameter than the small diameter portion 15d is formed at the rear end. And socket 2
The metal tube 14 is shorter than the socket 2 and has a plunger 15 at the front end opening.
The tube sliding contact portion 15b is slidably arranged so as to prevent the opening from being narrowed by caulking and coming out. Further, the tube sliding contact portion 1 inside the tube 14
A coil spring 6 is compressed between the rear end of the tube 5b and the narrowed rear end of the tube 14 to elastically bias the plunger gear 15 forward. In addition,
Plunger 15 and tube 14 are appropriately plated with a highly conductive metal.

In this configuration, when the tip of the contact probe 13 inserted into the socket 2 comes into contact with the test point of the circuit board to be tested, the plunger 15 retreats against the elasticity of the coil spring 6. It comes into contact with the inspection point. Here, the socket sliding portion 15c and the contact needle 15a can have an inner diameter of 1.37 mm, which is the inner diameter of the socket 2. Therefore, compared to the outer diameter of 0.75 mm of the contact needle 5a of the conventional plunger 3 shown in FIG.
The mechanical strength of 5a can be significantly improved. Further, the plunger 15 is connected to the socket sliding portion 1
5c to the socket 2, and the tube 1 is connected from the tube sliding contact portion 15b to the tube 1.
Electrical continuity is provided to socket 2 via 4, and 2
Reliability can be improved by electrical continuity of the path. In particular, the electrical continuity between the tube sliding contact portion 15b and the tube 14 is highly reliable because the sliding contact portion between the socket sliding contact portion 15c and the socket 2 prevents flux, dust, etc. from entering. moreover,
Since the plunger 15 is slidably supported at two locations, the socket sliding contact portion 15c and the tube sliding contact portion 15b, it is easy to increase the distance between the two supported locations, and the sliding frictional resistance does not become particularly large. The deviation from the axis can be reduced, and the contact needle 15a can be accurately brought into contact with the inspection point of the circuit board to be inspected.

FIG. 2 is a longitudinal sectional view of another embodiment of the contact probe of the present invention. In FIG. 2, the same members as those in FIG. 1 are given the same reference numerals and redundant explanations will be omitted.

The contact probe 13' shown in FIG.
The structures of the contact probe 13 and the plunger 15' shown in FIG. 1 are partially different.
That is, a narrow diameter portion 15e with a slightly smaller outer diameter is formed at the axial center of the socket sliding portion 15c formed at the intermediate portion of the plunger 15'. Also,
A contact needle 15a' formed at the front portion of the socket sliding contact portion 15c has an outer diameter smaller than that of the socket sliding contact portion 15c.

With this configuration, the area of the socket sliding portion 15c that slides on the inner periphery of the socket 2 is reduced, the sliding frictional resistance can be reduced, and the plunger can slide more smoothly. Further, the diameter of the contact needle 15a' is appropriately set depending on the size of the inspection point.

(Effects of the Invention) As explained above, according to the contact probe of the present invention, the contact needle of the plunger can be made thicker and the mechanical strength can be increased. In addition, electrical continuity is ensured, and the tip of the contact needle can be accurately brought into contact with the inspection point without shifting, resulting in an excellent effect of improving the reliability of the inspection.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of one embodiment of the contact probe of the present invention, FIG. 2 is a longitudinal cross-sectional view of another embodiment of the contact probe of the present invention, and FIG. FIG. 2 is a vertical cross-sectional view of an example of a conventional contact probe. 1...Mounting pin board, 2...Socket, 3,
13,13'...Contact probe, 4,1
4...Tube, 5, 15, 15'...Plunger, 6...Coil spring, 15b...Tube sliding contact part, 15c...Socket sliding contact part, 15d
...Small diameter section.

Claims (1)

[Scope of utility model registration request] In a contact probe to be inserted into a cylindrical socket with an open front end disposed on a mounting pin board, a socket sliding contact part is formed in the middle part of the plunger for slidingly contacting the inner periphery of the socket, and this socket A small diameter part is formed at the rear intermediate part of the sliding contact part, and a tube sliding part having a larger diameter than the small diameter part is formed at the rear end, and the tube is inserted into the socket and is inserted into the front end opening of the tube which is shorter than the socket. The tube sliding contact portion is slidably arranged so as not to slip out forward, and a coil spring is compressed between the rear end of the tube sliding contact portion in the tube and the rear end portion of the tube. A contact probe characterized by comprising: