DE3507464A1 - Spring contact pin - Google Patents

Abstract

A spring contact pin for making contact with points on test items such as printed-circuit boards and the like, which points are located close to one another in at least one row. Said pin has a piston, which is guided in a sliding manner in an outer tube and is loaded by a spring, and in the case of which the cross-section of the outer tube and of the region of the piston guided in it are greater in one direction than in the direction which is perpendicular thereto.

Description

Spring contact pin

The present invention relates to a spring contact pin according to the Preamble of claim 1. Test adapters are used to simultaneously test a A plurality or a large number of points (test points) of the respective test item in order to determine whether all conductors and other electrical or electronic components of the test object are intact and can fulfill their intended functions.

With such test items as printed circuit boards, integrated circuits or the like., It often happens that they have at least one straight series of at the same time Have contacts to be checked or other test centers to be contacted who are very close to each other in the row, whereas in the direction transverse to one such row the spacing of the next test points of this series is considerably larger. The known spring contact pins have a circular cross section Jackets and pistons.

The pistons are driven by pre-tensioned helical compression springs located in the jacket tube burdened. For reliable contact with the test points of the test items through the tips or heads of the pistons, the helical compression springs must have relatively large forces of generally mostly 50-300 cN (grams). This requirement makes it possible to to reduce the diameter of the jacket tube of such known spring contact pins, Limits. Attempts have been made to remedy this by using the plunger of a spring contact pin a thin, wire-shaped extension connected and this in a cannula up to close led to the examinee (yearbook of the German Society for Chronometrie, Vol. 30, 1979, pp. 269-276). The free ends of the appendages could thus be moved closer together than the spring contact pins themselves. However, this resulted in a very difficult to manufacture, sensitive and expensive construction. The long appendages are in the Cannulas do not guide smoothly, and disturbances and reductions easily occur the force exerted by the spring on the piston on the path of the appendix in the cannula on.

It is an object of the invention to provide spring contact pins so train that they are simple, inexpensive and not prone to failure design particularly small center-to-center distances of test points arranged in a straight row of test objects.

This task is accomplished with the features of the characterizing part of the claim 1 solved. The invention allows the spring contact pins in the transverse direction very much to make them thin and still have them and their feathers as well as their casing tubes and pistons still sufficiently stable. In particular, even at extremely low minimum thickness of the jacket tube still relatively strong springs are provided. the Spring forces can expediently be around 50 to 300 cN. The spring contact pins according to the invention are reliable and relatively inexpensive in the Manufacture and the pistons have little friction.

The use of such spring contact pins is particularly advantageous when testing specimens, which are arranged in straight rows, each with a spring contact pin Test points to be contacted, such as contacts or the like. Have those in the series are very close to each other, while the lateral distance of this row to others Test centers or rows of test centers is larger, especially if the test centers are arranged in series in a linear grid. Such straight rows of Test centers often form Connection contacts of printed circuit boards, of integrated Circuits or the like.

In a particularly favorable embodiment, the cross section of the Casing tube of the spring contact pin in the longitudinal direction at least 1.2 flat, preferably at least twice as long as in the transverse direction.

The jacket tube is particularly useful by deforming a circular cylindrical one Pipe made, preferably by upsetting, with exact, constant dimensions of the cross-section must be observed.

Above all, a particularly small width in the transverse direction can be achieved achieve when the outline of the cross-section consists of two parallels passing through Roundings are connected. The spring loading the piston can advantageously also be designed so that they are extended in the longitudinal direction of the cross section is than transverse to it, preferably a flat spiral spring. In the simplest case it has they take the form of a rod that relaxed from its little curved or straight line Location is deflected. For greater spring travel, the spring is useful as a flexible spring formed with several serpentine turns.

Especially for longer distances and a flat spring characteristic it is convenient to arrange a tension spring especially a coil spring, which is attached to the piston at its rear end and to the jacket tube at its front end is. The piston has a recess that receives the tension spring.

To achieve good electrical contact, the spring is on their ends suitably welded or soldered to the piston and / or the jacket tube. If by suitable measures, especially exact fit and non-corrosive Surfaces, good current transfer between the piston and jacket tube is ensured, a conductive connection via the spring can be dispensed with. The spring can then also advantageously consist of a non-conductive material such as rubber.

It is particularly useful to close the jacket tube with a stop provided against which the piston rests under the force of the spring in its rest position. The jacket pipe is advantageously closed at its rear end by a cover, which serves as the contact end to which connecting lines are attached particularly easily can be. The piston protrudes continuously from the jacket tube at its rear end out, it is advantageous to use this end as a contact end for attaching a Train connection.

The jacket tube can expediently be approximately constant over its length Have cross-sectional profile. It can preferably be provided that the cross section of the jacket tube over the entire axial length or almost over the axial length of the Jacket pipe is constant. It is particularly useful if the cross section of the Jacket pipe its front end to form a stop for the piston is reduced and that the jacket tube is cylindrical over its remaining length is.

The spring contact pin according to the invention has the advantage that it is in Be very narrow transverse direction of the elongated cross section of its jacket tube can, preferably about 0.4 to 3 mm, so that the contact pins can form rows, in which they have very small center-to-center distances from one another, only slightly greater than their thickness measured in the transverse direction of their jacket pipe cross-section of the jacket pipe are. Center-to-center distances can be as small as they are not possible with spring contact pins with circular cylindrical casing tubes. The invention thus opens up the possibility of testing such in straight rows arranged test centers to be able to carry out even if these center distances are so small that they can be connected to the conventional spring contact pins with casing tubes circular cylindrical cross-section without projections guided in cannulas either could be tested remotely. The invention thus also enables such test centers to be arranged on the test items at shorter intervals than before and so also one to carry out further miniaturization of such test objects.

The longitudinal direction of the cross section of the jacket tube of the invention Spring contact pin can be relatively wide, for example 1-10 mm, preferably approx. 3 mm, which ensures low-friction, secure guidance of the piston in the jacket tube and a good current transfer even under unfavorable conditions secured are. The spring contact pin is also relatively robust in terms of installation and operation relieved.

The free end intended to come into contact with the test object (tip, Head or the like) of the piston can be of any desired shape, e.g.

conical or hollow conical, with smooth, angular or notched Surface or be formed in some other way.

The spring contact pin can also be manufactured economically. Thus, the jacket pipe can easily be formed by deforming a pipe with a circular cross-section getting produced. The piston can also be passed through from a round wire Manufacture flat rolls with the desired flat profile.

Embodiments of the invention are shown in the drawing. They show, greatly enlarged: FIG. 1 a spring contact pin according to a first exemplary embodiment the invention in a view obliquely from above, Fig. 2 is a corresponding view of a second embodiment, FIG. 3 the side view of a third embodiment, 4 shows a sectional plan view of a test object.

The straight metallic, essentially cylindrical flat tube 1 of the spring contact pin 40 shown in FIG. 1 has a cross section that corresponds to its upper, rear end seen obliquely from above can be seen and its Outline consists of two parallels 2 and 3, which are connected by roundings 4 and 5 are. The length x of this cross-section measured in the longitudinal direction of the cross-section is significantly larger than the dimension y of this cross-section across it, that is the distance of the parallels 2 and 3 from each other, which parallel side surfaces of the jacket pipe. The length x of the cross section can preferably be approx. 1-10 mm and its width y is preferably 0.4-3 mm. The larger cross-sectional dimensions can be particularly useful when particularly high spring forces on the Pistons are to be exercised. The lowest smallest values for its width y can be considerable the diameter of spring contact probes below the minimum values achieved so far lying with circular cylindrical casing pipes.

It is also important for such spring contact pins that they be small electrical resistance so that they do not carry out the electrical test of the device under test distort. Let spring contact pins according to the invention easily Manufacture with very low electrical resistance.

The jacket pipe 1 is at its lower, d. H. front end a little withdrawn, d. i.e. flanged inwards and thus has a narrowing at the front its cross-section, as a stop 6 for a shoulder 13 of a straight Piston 11 is used. On its remaining length, the jacket pipe has 1 - as shown -constant cross-section so that it is cylindrical with the exception of its shoulder (stop 6) is. On the top, rear end of the jacket tube 1 is a metallic Put on cover 7, which closes it. He has an extension 8 with a trough 9 for receiving a lead wire that is electrically conductive as a whole Spring contact pin 40 with an evaluation device for evaluating when testing of DUTs, such as 18, conducted by the spring contact pin 40 electrical signals connects. The cover 7 thus serves as a contact end 10 and can be inserted into the jacket tube 1 pressed in, crimped, by soldering or welding or the like.

be connected. The connecting wire can be soldered into the trough 9 or it is fastened by crimping or plugging or the like, possibly also by welding.

In the jacket tube 1, the metallic piston 11 is slidably guided straight. Its rear part (in the drawing above) is designed as a guide part 12 and fits into the jacket tube 1 with slide bearing play, so that it fits in the jacket tube 1 guided cylindrical guide part 12 has a cross section that corresponds to the inner cross section corresponds to the cylindrical area of the jacket tube 1 with slide bearing play. Of the Probe part 14 of the piston 11 can, if desired, in the area in which it penetrates the front lower (front) opening of the jacket pipe 1, have a cross section that corresponds to the clear cross section of this opening with slide bearing play equals or is smaller. He goes with his shoulder 13 in the straight probe part 14, which ends in a contact tip 15. He can depending on the requirements the test process taper into a hollow cone and angular or notched surfaces to have. It ends with a conical point 16 or small edges.

So that it penetrates any oxide skins, dirt or other that Conductivity impairing coatings on the contact to be tested 17 or the other test center of a test item to be contacted by him 18. The test item 18 can, for example, be an integrated circuit, the connections of which are used as contacts 17 are formed and arranged in straight rows. In Fig. 4 there are two rows of such Contacts 17 of a circuit board 18 or the like. Shown. The center-to-center distance a two adjacent rows of contacts 17 is when their centers are simultaneously through the Tips 16 of spring contact pins arranged in two rows in a test adapter 40 should be contacted, larger than x, while the contacts 17 of each row only need to have center-to-center distances b of only a little more than y.

Instead of the jacket tube 1 with the exception of its reduced cross-section Form stop 6 cylindrical over its remaining length, if the Spring 19 allows also to be provided that the rear region of the jacket tube 1, which does not serve to guide the piston 11, over at least part of it Length in cross section is reduced.

A metallic compression spring is located between the piston 11 and the cover 7 19 clamped in, it is in the tense condition slightly curved or straight, and at their ends in bores 20, 21 of piston 11 and cover 7 through Welding, in particular with a laser or electron beam, attached. But she can also be soldered or clamped depending on the requirements. When assembling of the spring contact pin 40, it is compressed and thereby deflected further. Then the cover 7 is attached. The spring then presses the piston with pretension 11 with its shoulder 13 against the stop 6 of the jacket tube 1. Instead of the one Several essentially parallel springs can also be used.

When testing a test item 18, the test adapter becomes the test item 18 so approximated that the piston 11 of its spring contact pins out of their rest position be pushed back. Their tips 16 are then under the force of the springs 19 with such a force on the contacts 17 or the like. That they are there with certainty establish an electrically conductive connection.

With the help of the evaluation device mentioned, all carry out the necessary tests automatically and quickly.

In the case of the spring contact pin 40 'according to FIG. 2, the metallic jacket tube is 22 designed like that of FIG. The metallic piston 23 also corresponds to this of the first embodiment. The cover of the jacket tube 22 has no special one Appendix; it serves directly as the contact end 24. The one between the contact end 24 and the piston 23 clamped metallic spring 25 has several, flat, serpentine bends 26. Its ends are like the spring 19 of the previous one For example, fastened and presses the piston 23 with bias in its rest position, in which his shoulder 27 rests against a stop 28 of the jacket tube.

If the spring contact pin 40 'is placed on a test object, it pushes this the piston 23 against the force of the spring 25 backwards. The tracking force at the top of the piston ensures a secure electrical connection between the Piston and contact 17 of test object 29.

In the case of the spring contact pin 40 ″ according to FIG. 3, the metallic jacket tube is 30 designed in accordance with the previous exemplary embodiments, but does not have any Lid. The piston 31 is on its probe part 32 also as in the previous one Examples trained. Its guide part 33 protrudes backwards from the jacket tube 30 out. Its rear end serves as a contact end 34 on which a connecting wire is attached.

A longitudinal end is located in the middle of the metallic piston 31 Recess (breakthrough) 35. In it lies a coiled tension spring Spring 36.

At its rear end it is hooked into a hole 37 of the piston 31, at its front end on a pin 38 which extends transversely through the jacket tube 30 and the opening 35 is inserted.

In the rest position shown, the spring 36 pulls the piston 31 into its front end position, in which he piston 31 at the lower constriction of the jacket tube 30 is applied, which corresponds to the stop 6 of the jacket tube 11 of FIG. 1; or it instead of this constriction, provision can also be made for the piston 31 to have a widening has, with which it is in its lowest position on the upper edge of the jacket pipe 30 is applied to limit its downward movement, so that the jacket pipe 30 continuous can be cylindrical. The spring 36 is in the lowest position of the piston 31 a certain bias. If the piston: to a point to be tested on a test object put on, it is pushed back and is under the force of the spring 36 with such an overlay pressure on the contact that it penetrates, for example, interfering layers and creates a well-conducting connection.

The size of the spring force and its characteristics can be let through Use a suitable spring to adjust the desired values within wide limits.

The front rest position of the piston can also be determined by a stop be that is designed differently than a shoulder of the jacket pipe, for example.

a cross pin. The springs can, especially if their ends are welded on or are soldered, the electrical connection between the piston and the jacket tube to ensure. With a suitable design of the surfaces according to shape and material This connection can also be dispensed with, as the jacket tube and piston are large Have contact surfaces.

A copper alloy is preferably used as the material for the jacket pipe, e.g. tin bronze, used for the piston steel or copper beryllium, for the Compression springs are a hardenable precious metal alloy or copper beryllium, for which Tension spring, for example steel.

The contact end can be made of brass, for example. For the areas that should form conductive transitions, coatings made of nickel, Silver, Gold or rhodium can be provided.

If the spring is not needed as a conductive part, it can also consist of non-conductive material, e.g. rubber, especially if they is designed as a tension spring.

The cross-section of the jacket tube and piston can instead of two Parallels limited in shape depending on the space available, others too have an elongated, preferably oval shape. The springs do not then need to be completely flat to be, but can also have a slightly larger extension in the transverse direction, which improves their stability. The piston does not have to fit on the entire circumference The jacket pipe rest on, but only so far that it is safely guided and the current transition is guaranteed. It can be beneficial to do something that is not necessary for the guide Provide recesses on the piston surface so that the piston can be attached to the leading places can be better fitted. The electrical resistances of the Contact pins 40, 40 ', 40 "from their contact tips, such as 16, to their contact ends, like 10, can be kept very small.

In all embodiments, the jacket tube is designed so that the outline of the maximum cross section of the jacket tube 1; 22; 30 into a geometric Rectangle fits whose long sides are parallel to the longitudinal direction (x) and whose short sides Sides parallel to the transverse direction (y) of the cross section of the casing tube 1; 22; 30th run, this outline with each of these four sides of the geometric rectangle has at least one point in common each.

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Claims (20)

Claims 1. Spring contact pin for with a large number of spring contact pins Test adapters that can be equipped for contacting test objects for the purpose of testing them electrical faultlessness, such as printed circuit boards, integrated circuits or the like., which spring contact pin has a piston which is used to contact test points has, which agitated axially movably in a 01antelrohr and of at least one Spring is loaded in the direction of its rest position, d u r c h g e k e n n -z e i c h n e t that the cross-sectional dimensions of the casing tube (1; 22; 30) and of the area of the piston guided in it in one direction (longitudinal direction x of the Cross-section) larger than in the direction perpendicular to it (transverse direction y of the transverse cut) are. 2. Spring contact pin according to claim 1, characterized in that the outline of the maximum cross section of the jacket tube (1; 22; 3C) into a geometric Rectangle fits whose long sides are parallel to the longitudinal direction (x) and whose short sides Sides parallel to the transverse direction (y) of the cross section of the casing tube (1; 22; 30), this outline with each of these four sides of the geometric Rectangle has at least one point in common. 3. Spring contact pin according to claim 1 or 2, characterized in that that the cross section of the jacket tube (1; 22; 30) in the longitudinal direction (x) at least 1.2 is flat as long as in the transverse direction (y). 4. Spring contact pin according to one of claims 1 - 3, characterized in that that the outline of the cross section of the jacket tube has the shape of an oval. 5. Spring contact pin according to one of claims 1 - 3, characterized in that that the outline of the cross section of the jacket tube consists of two parallels (2, 3), which are connected by curves (4, 5). 6. Spring contact pin according to one of claims 1 to 5, characterized in that that the spring (19, 25) is a compression spring in the form of a spiral spring. 7. spring contact pin according to claim 6, characterized in that the spiral spring (19) consists of at least one slightly curved in the relaxed state or straight wire or strip. 8. spring contact pin according to claim 6, characterized in that the spiral spring (25) has several serpentine bends (26), 9. Spring contact pin according to one of claims 1 - 5, characterized in that the spring (36) one Tension spring, preferably helical spring, and in a recess (35) in the piston (31) is housed. 10. Spring contact pin according to one of claims 1 -that is, that the spring (19; 25; 36) with the piston (11; 23; 31) and / or with the jacket tube (1; 22; 30), preferably with its contact end (10; 24), is welded. 11. Spring contact pin according to one of claims 1 - 9, characterized in that that the spring (19; 25; 36) with the piston (11; 23; 31) and preferably also with the jacket tube (1; 22; 30) is connected by soldering. 12. Spring contact pin according to one of claims 1 - 9, characterized in that that the spring is made of elastomeric material, preferably rubber. 13. Spring contact pin according to one of claims 1 - 12, characterized in that that the jacket tube (1; 22; 30) produced by deforming a circular cylindrical tube is. 14. Spring contact pin according to one of the preceding claims, characterized characterized in that the jacket tube (19; 25; 36) over its entire axial length or is approximately cylindrical over almost its axial length. 15. Spring contact pin according to one of claims 1 - 14, characterized in that that the jacket tube (1; 22; 30) has a stop (6l against which the piston (11; 23; 31) under the force of the spring (19; 25; 36) in its rest position is present. 16. Spring contact pin according to claim 14 and 15, characterized in that that the cross section of the jacket tube (1; 22; 30) at its front end to form of the stop for the piston (11; 23; 31) is reduced and the jacket tube over its remaining length is cylindrical. 17. Spring contact pin according to one of claims 1 to 16, characterized in that that the jacket tube (1; 22) closed at its rear end by a cover (7) is designed as a contact end (10; 24) for attaching connecting lines is, in particular has an extension (8) adapted to a wire end. 18. Spring contact pin according to one of claims 1 - 16, characterized in that that the piston (31) protrudes at its rear end from the jacket tube (30). 19. Spring contact pin according to one of claims 1 - 17, characterized in that that the spring (19; 25) is arranged completely within the casing tube (1; 22) Feather is. 20. Spring contact pin according to one of the preceding claims, characterized characterized in that the cross section of the jacket tube (1; 22; 30) in the longitudinal direction (x) is at least twice as long as in the transverse direction (y).