DE8706546U1 - Spring contact pin - Google Patents

Description

5860IP-5-

\ Fine Metal GmbH

7033 Herrenberg

Spring contact pin

The invention relates to a spring contact pin for

,_ Test equipment used for testing electrical, Ib

in particular electronic test objects, such as circuit boards or the like.

Test devices of this type are known (e.g.

KRÜGER "Test equipment for electrical testing of 20

Printed circuit boards for watches", Yearbook of the German Society for Chronometry ₄ Volume 3O ₁ 1979, pp. 269-276). Such test devices are used to test printed circuit boards or other electrical,

_,. especially electronic components, to create new Zo

to be able to quickly and easily check or measure manufactured circuit boards or similar before or after they are assembled to ensure that they are free from defects, for which purpose the test object is tested on several or generally most

„ .'very many places at the same time by 30

Spring contact pins of the test device electrically

The test points are often very close to each other, and the closer they are, the narrower the conductors and the smaller the conductor spacing of the

Such 35

§ t Ii ····

5860IP-1

Testing devices are often used to check the conductor tracks of unpopulated circuit boards for short circuits between adjacent conductor tracks or other conductor track errors, e.g. interruptions or the like, before they are populated with further electronic components.

\q When testing a test object, the free front ends, i.e. the contact heads of the contact pins, which can in particular form contact tips, are pressed against predetermined points on the test object in question so that good electrical contact is made with them. The pressing force is usually in a range of approx. 80 - 500 cN and is applied by the spring of the spring contact pin in question.* The spring contact pin is therefore used to come into good electrical contact with a predetermined point on the test object in question and to form an electrical conductor with a low electrical resistance. The spring contact pin is normally connected with its rear end or rear end area in the test device to an onward electrical conductor which normally leads to an evaluator which, when testing each test object, after the electrical voltage or voltages have been applied, evaluates the electrical currents or voltages conducted by the spring contact pins to determine whether the test object is electrically perfect or not.

In order for the evaluator to work properly, it is important that it is used with the respective test subject

5860 IP-7-

The electrically connecting conductors have low electrical resistance values, which should generally be within relatively narrow limits, whereby the narrower these limits can be kept and the lower these resistance values are, the better. These resistance values are crucially dependent on the contact resistances of the spring contact pins that form the electrical conductors. The electrical contact resistance of a spring contact pin is its ohmic resistance from the free front end of its contact pin to its rear connection end. This contact resistance is crucially dependent on the ohmic contact resistance between the piston of the contact pin and the cylinder of the cylinder member containing the piston.

In the known spring contact pins, the sliding surfaces of the pistons of the contact pins are circular-cylindrical. Such spring contact pins are often exposed to hundreds of thousands or millions of

Subjected to load changes in which the piston is on the Zo

The cylinder member's raceway slides, with the result that abrasion occurs, which causes contamination, which increases the electrical contact resistance between the piston member and the cylinder member. The wear between the piston and the cylinder member can also increase the contact resistance in itself, for example by having an electrically particularly conductive outer coating on the piston and/or the cylinder's raceway

This wear can also affect the 36

5860 IP-8--

Limit the service life of the spring contact pin. 5

It is an object of the invention to create a spring contact pin according to the preamble of claim 1, which is exposed to only extremely low wear on the contact surface or surfaces present between the piston and the cylinder member when the piston slides in the cylinder member, so that hardly any or only very little abrasion occurs here.

This object is achieved according to the invention by the spring contact pin according to claim 1.

The spherical formation of at least one

I Sliding surface of the piston, with which it '

starting from the front rest position of the contact pin, in which it is centered to the cylinder, i.e. in which the contact pin is aligned or arranged coaxially to the cylinder, on the running track of the cylinder member, surprisingly results in particularly low wear. There is no or only extremely little abrasion. The spring contact pin can thus withstand a particularly large number of load changes and take part in a correspondingly large number of test procedures. The electrical contact resistance between the piston and the cylinder member also does not increase or only increases relatively slowly with the number of load changes. Tests in comparison with conventional spring contact pins, which differ from spring contact pins according to the invention only in that the piston sliding surface or surfaces

• * * III! • · · » IfI

5860 - 9 -

was or were not crowned but circular-cylindrical IJj ₁ , resulted in significantly less wear and hardly any abrasion for the spring contact pins according to the invention. The low or lack of abrasion also reduces or prevents the formation of the electrical

.Q Contact resistance between sliding surface and running surface increasing Coatings on the sliding and running surfaces of the piston and cylinder.

The crowned sliding surface of the piston, if it has several crowned sliding surfaces, all of these sliding surfaces are conveniently located permanently inside the cylinder.

Preferably, it can be provided that the or at least one spherical sliding surface of the piston is rotationally symmetrical. However, it is also conceivable that in some cases one can deviate from the rotational symmetry, for example by working narrow longitudinal grooves arranged at the same central angle from one another on the circumference of the piston, which extend in axial directions.

It is particularly advantageous to provide that the or at least one spherical sliding surface of the ^ ₀ piston is formed by a spherical zone of the piston.

Such a ball zone can be manufactured particularly easily and precisely. It has also been shown that it results in particularly low wear.

iMi
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· · 4 II &igr; ·

5860 IP-10-

In many cases it is desirable for the piston to be guided straight in the cylinder member so that the centering to the cylinder that exists in the rest position of the contact bolt is also constantly maintained during the axial movements of the contact bolt relative to the cylinder, so that both parts remain constantly aligned coaxially with each other. This can be achieved in a simple way by providing the piston with two spherical sliding surfaces that are arranged at an axial distance from each other.

Although the formation of the piston sliding surface using a spherical zone is particularly advantageous, other spherical designs of the sliding surface are also possible. For example, the spherical sliding surface can often be used

by a barrel-shaped, oval, ellipsoidal or 20

convexly curved area of the contact pin, approximating a spherical zone. In a particularly advantageous embodiment, the piston has a single spherical sliding surface

and a shaft of the 25

contact bolt can penetrate an opening in the cylinder member during operation with such a large lateral play that during operation the contact bolt, if it is not in its front rest position, in which its

Contact head is unloaded. As a result of the only 30

The spherically shaped sliding surface can pivot transversely to its longitudinal direction for self-centering of the contact head of the contact bolt in recesses, sockets or the like of test objects.

IP-11-

The drawing shows examples of the

Invention shown. Shown are:
6

Fig. 1-4 one spring contact pin each according to

Embodiments of the invention in
partially broken and cut lengthwise

representations.
IO

Fig. 5 is an enlarged detail of Fig. 3,

In Fig. 1, the flat plate 10 of a test adapter

a testing device for printed circuit boards or the like |

indicated, in which plate 10 a multitude of " |

identically designed spring contact pins, namely I

usually hundreds to several or many thousands §

Spring contact pins can be firmly inserted, from |

which a spring contact pin 11 is cut lengthwise j

is shown. |

This spring contact pin 11 consists of an i

Cylinder member 14, a rigid or stiff |

rotationally symmetrical contact pin 18 and one Ir

Contact bolt 18 in outward direction loading,
inside the rotationally symmetrical cylinder 15 of the
Cylinder member 14 arranged on the bottom 28 of the ■

Cylinder 15 supporting, pre-tensioned

Helical compression spring 19. At the rear end of the f

sleeve-shaped cylinder 15 also includes a
Diameter reduced metallic pin 12 for
the electrical connection of this spring contact pin
11. All parts of this spring contact pin are

5860IP-1

- 12 -

metallic. Coatings made of precious metals, precious metal alloys, nickel or the like can also be provided to reduce the electrical contact resistance between the rigid or stiff piston 17 and the cylinder 15. The casing tube of the cylinder 15 is circular-cylindrical with the exception of a constriction 26. The straight, solid contact bolt 18 can be designed in one piece and has, coaxially to one another, the single piston 17, a shaft 16 and an enlarged contact head 20 designed as a contact tip, which forms the free front end of the contact bolt 18, which is constantly located outside the cylinder member 14 and thus its cylinder 15 and which serves to come into contact with test objects such as 27. The cylinder member 14 here consists of the cylinder 15 and the pin 12 attached to its base 28. The contact bolt 18 constantly protrudes from the cylinder J5.

In this embodiment, the solid piston 17 consists of two spherical layers 22 and 22' arranged at an axial longitudinal distance from one another and a circular cylindrical connecting rod 21 connecting them. The surfaces of the spherical layers 22, 22' each form a spherical zone 24 and 24' of the same radius. The geometric plane bisecting the individual spherical layer 22 and 22" and thus the relevant spherical zone 24 and 24' and perpendicularly intersecting the longitudinal axis of the solid contact bolt 18 is a plane of symmetry of the relevant spherical zone 24 and 24' and spherical layer 22 and 22'. Each spherical zone 24 and 24' is an annular section of a geometric spherical surface. The

5860IP-1

- 13 -

Ball zone 24 or 24' thus forms a spherical sliding surface with a constant radius of curvature, with which the piston 17 can slide in the cylinder 15, whereby these sliding surfaces are extremely narrow areas of the ball zones 22, 22', namely the almost linear areas where the ball zones 22, 22' contact the cylinder 15. The two ball zones 24 or 24' of the piston 17 are located inside the cylinder 15 and can slide axially on its cylinder track 25, 25', which is divided into two parts and is provided on the inner circumference, with little sliding bearing play and thus form the only sliding surfaces of the piston 17, which are therefore always located inside the cylinder 15. Both partial tracks 25, 25' are circular cylindrical and have the same diameter. A constriction 26 is provided in the jacket of the cylinder 15, which forms an inwardly directed ring collar that forms a stop for the rear ball layer 22', so that the spring 19 presses this rear ball layer 22' against this stop 26 as long as the contact bolt 18 is in its rest position shown, in which its contact head 20 is unloaded. As a result of the two ball zones 22, 22", the contact bolt 18 is constantly centered in relation to the cylinder member 14, so that the

30- Longitudinal axis of the contact bolt 18 always coincides with the longitudinal axis of the cylinder 15, i.e. the contact bolt 18 always remains coaxial with the cylinder 15.

The cylinder 15 is completely open at its end adjacent to the contact tip 20 and the

5860 IP-14-

Contact tip 20 adjacent front ball layer

is in the resting position shown of the

P6

if contact bolt 18 is still in cylinder 15 but close to its

front free end.

I Piston 17 is the only piston of this

j Fire contact Softes. It is also the only

10
I Piston, which is involved in the movement of the contact bolt 18

f participates.

') If 27 people are required to test a candidate, e.g.

j Printed circuit board, the contact head 20 of the contact bolt

" of the spring contact pin 11 to a contact

i ₄ point of the test piece 27 is pressed and the

I test piece then the contact bolt 18 in the cylinder 15

I axially backwards, the two

I spherical layers 22, 22' on the circular cylindrical,

1 20

I two-part raceway 25, 25' of the cylinder 15, and

I this track 25, 25' forms a straight line for

I these, the two spherical layers 22, 22' and the

1 connecting rod 21 having piston 17.

I These two spherical layers 22, 22' cause

I surprisingly found that the sliding of the

1 massive piston 17 in cylinder 15 occurring

I Wear and abrasion is extremely low, namely

considerably lower than if, with otherwise the same 1 design of the spring contact pin instead of the

Ball zones 24, 24' would have circular cylindrical piston sections in a known manner. It occurs in the spring contact pin 11 shown in the

Cylinder 15 due to the spherical layers 22, 22' 35

5860 IP-15-

There is practically no abrasion and therefore practically no contamination, which would increase the electrical contact resistance. The electrical contact resistance between the cylinder 15 and the piston 17 changes little or not at all with the number of load changes that cause the piston 17 to slide in the cylinder 15. The electrical contact resistance is also very low.

The spring contact pin 11 according to Fig. 2 differs from that according to Fig. 1 only by the displacement of the stop 26 for the rest position of the spring-loaded contact bolt 18 to the front end of the cylinder 15, in that this front end is flanged inwards and thus here forms a stop 26' for the front ball layer 22 of the solid contact bolt 18

The career 25 is undivided here. 20

The spring contact pin 11 according to Fig. 3 and 5 also has a cylinder member 14 and a one-piece, solid contact bolt 18 and a pre-stressed

^" helical compression spring 19. The cylinder 15 of the cylinder member 14 is again provided at the front end with an inwardly directed ring-shaped flange 26', which forms a stop forming an annular surface for a truncated cone-shaped ring shoulder 29

of the straight solid contact bolt 18 for the illustrated front rest position of the solid contact bolt 18. The outside diameter of this ring shoulder 29 and thus the diameter of a

below the circular cylindrical rod 30 36

• Uli · I ti «III! t

5860IP-16-

is considerably smaller than the inner diameter of the \

c one-piece, circular cylindrical raceway 25 of this

Cylinder 15, on which only the single I

Ball layer 22' with its ball zone 24', which forms the only sliding surface of this piston 17, can slide with little sliding bearing play, which ball layer 22' is arranged here at the rear end of the rod 30 and its radius is slightly smaller than the radius of the raceway 25. The spring 19, as with the other spring contact pins 11, is supported by a rear, tapered shoulder 33 of the piston 17, while being centered. The shoulder 33 adjoins the ball layer 22' coaxially to it.

The inner diameter of the annular flange 26'

is considerably larger than the diameter of the 20

shaft 16, which can penetrate the circular opening of the cylinder 15 formed by this inner flange or shoulder 26' during operation. This has the consequence that the contact bolt 18, when it is

Stop 26' is lifted, as in a 26

Ball joint can pivot, as shown in dash-dotted lines in Fig. 5. The ball layer 22' forms the "ball head" of this "ball joint", which, however, does not have

pan, but instead comes the 30

Raceway 25 of the cylinder 15. This spring contact pin 11 also experiences extremely low wear during operation when the ball layer 22' slides on the inner raceway 25 of the cylinder 15 and thus practically no abrasion, so that the

• till I

• · « · · · · · · 5860 IP -M-

electrical contact resistance between ball layer 22' and cylinder 15 over many strokes of the

5

* piston and thus over many load changes of the

% spring contact pin does not change or changes only slightly.

Also, the electrical contact resistance between

f the piston and the cylinder 15 despite the small

Contact surface very low. A special advantage of this spring contact pin 11 is the following:

In the front rest position shown, the contact bolt 18 is centered in the opening 40 due to its tapered, here truncated cone-shaped, annular shoulder 29 coaxial to the longitudinal axis of the contact bolt and thus centered to the cylinder 15, so that the contact bolt 18 is in contact with a test object before it contacts it.

precisely defined position, by

20

this front rest position of the contact bolt 18

its longitudinal axis coincides with the longitudinal axis of the cylinder member 14, i.e. contact bolt 18 and cylinder 15 are aligned coaxially with each other. If the

Contact tip 20 of the contact bolt a recess

25

or similar, e.g. here a contact socket 35 of a

If the test object 27 is contacted and the contact pin is pressed downwards by the test object, this contact tip 20 can move thanks to the ball layer 22' and the

large side play of the shaft 16 in the central

30

Opening 40 of the inner shoulder 26' while pivoting

by means of this "ball joint" in the bore 34 of the bushing 35, which allows better contact between this bushing 35 and the contact tip 20 and thus

here lower electrical contact resistance than 35

5860 IP-18-

if centering does not occur and also reduces the stress on the spring contact pin 11, facilitates the sliding of the piston 17 and the

Wear of piston 17 and cylinder bore 25 still &ogr;

further reduced. If the contact bolt 18 becomes out of alignment with the cylinder 15 when contacting a test object 27, i.e. is decentered relative to it, its position, centered again with the cylinder 15, i.e. aligned with the cylinder 15, in which their longitudinal axes coincide again, is automatically reset when it returns to its front rest position under pressure from the spring 19. All of this is therefore extremely advantageous.

The solid, rigid or stiff contact bolt 18 of the spring contact pin 11 according to Fig. 4 has a single piston 17 which has a barrel-shaped, convex area 22" which can slide on the cylindrical track 25 of the cylinder 15 during operation. The piston 17 again has a tapered rear end into which the helical compression spring 19 engages. In the illustrated front rest position of the contact bolt 18, in which its contact head 20 is unloaded, its truncated cone-shaped annular shoulder 29 is pressed against the inner shoulder 26' of the cylinder 1b for centering the contact bolt 18 to the cylinder 15, so that in this rest position the longitudinal axes of the contact bolt 18 and the cylinder IC- and thus of the cylinder member 14 coincide. The through hole 40 formed in the front inner shoulder 26' of the cylinder 15 of the cylinder member 14 for the shaft 16 of the contact bolt 18 is again considerably larger in diameter than the circular cylindrical shaft 16, so that this contact bolt 18 can also center itself during operation on recesses or holes in the test object into which the conically tapered contact tip 20 penetrates, again by pivoting. The through hole 40 formed by the spherical, barrel-shaped,

5860 IP -&Igr;&Ogr;

The single sliding surface 24" of this piston 17, which is formed in the rotationally symmetrical region 22" along the longitudinal axis of the contact bolt 18, no longer has a constant radius of curvature. Rather, the radius of curvature in the circumferential direction of the piston 17 is

jQ considerably smaller than the radius of curvature in the geometric symmetry planes of the area 22" determined by the longitudinal center axis of the contact bolt 18. The latter radius of curvature can be constant or can vary over the length of the area 22" in a predetermined

ic way. If the contact bolt 18 is pressed further into the cylinder 15 by a test piece, the ring shoulder 29 lifts off the inner shoulder 26' of the cylinder 15 and now the only direct contact between the cylinder 15

~ _n and the piston 17 is only provided by the spherical sliding surface 24". As a result, this spring contact pin also results in extremely low wear and hardly any abrasion during operation and optimal contact with test objects.

In all embodiments, the solid pistons 17 and shafts IG are appropriate

rotationally symmetrical. The contact tip 20 can also be rotationally symmetrical, but it can also have a design that deviates from the "_0" rotational symmetry, for example it can be provided with cutting edges.

The contact bolt 18 or at least its piston 17 can preferably be made of coated or uncoated steel, particularly stainless steel, in particular hardened steel, preferably a

t I « « · «I
< II

&bull;&igr; I · · *

5860IP-IP

- 20 -

Hardness of over 400 Vickers, or made of coated or uncoated, tempered nickel-beryllium or coated or uncoated, tempered copper-beryllium. The copper-beryllium or nickel-beryllium can be hardened by heat treatment for tempering and preferably have a hardness of over 300 Vickers. If a coating is provided, it can preferably only consist of galvanically or chemically applied nickel or hard nickel. Or the coating can have a galvanically or chemically applied diffusion barrier made of nickel or hard nickel, on which a layer of precious metal or precious metal alloy is applied. The precious metal can preferably be gold, silver, hard gold, rhodium, palladium or alloys of these precious metals.

The cylinder 15 can preferably consist of a coated or uncoated copper alloy, such as bronze, brass, nickel silver, preferably unhardened copper-beryllium or the like, or coated or uncoated stainless steel. The copper-beryllium can preferably have a hardness of at least 220 Vickers, preferably from 220 to 320 Vickers. If the cylinder 15 has a coating, this can preferably form or help form the raceway 25 on which the sliding surface 24 or 24' or 24" of the piston 17 can slide. The coating can be single- or multi-layered, for example made of galvanically or chemically applied nickel or hard nickel, or made of precious metal or a precious metal alloy.

5860 IP-21-

If it is multi-layered, it can preferably consist of a nickel or hard nickel layer serving as a diffusion barrier, onto which a layer of precious metal or precious metal alloy is applied. The precious metal or precious metal alloy can preferably be silver, gold, palladium or alloys of these precious metals. The layer thickness of silver can be a maximum of 0.005 mm and that of gold and palladium a maximum of 0.002 mm.

All of the above-mentioned hard nickel layers can preferably have hardnesses of 400 to 1200 Vickers and thicknesses of at least 0.002 mm, preferably from approx. 0.002 to 0.007 mm.

The sliding surfaces 24, 24', 24" of the pistons 17 are extremely small, since they are ^spherical . These sliding surfaces and/or the track 25, 25' of the cylinder member 14, on which the respective sliding surface 24, 24' or 24' or 24" can slide, can be uncoated or preferably provided with coatings that further reduce the electrical contact resistance and/or further reduce wear. The coatings can, as mentioned, consist, for example, of hard nickel, precious metals, precious metal alloys or of other suitable metallic material or materials that have electrical conductivity. The coating can also be multi-layered, for example an inner layer of hard nickel can be coated with a thinner

outer layer of precious metal, e.g. gold plated 35

&bull;I 5860 IP - 22 -

In a spring contact pin examined in the test, which was designed in principle as shown in Fig. 1 f 6 and showed no detectable abrasion after 3 million load cycles, the contact pin consisted of steel coated with hard nickel and the cylinder member of silver-plated bronze, with the raceway 2B riga of the cylinder member also being thinly silver-plated.

Such spring contact pins are normally arranged at short intervals in usually very large numbers on so-called adapters or test adapters of test devices for testing circuit boards or other electrical or electronic test objects. The outside diameters of the cylinders 15 of the cylinder members 14 of the spring contact pins have only very small diameters of, for example, 0.5 to 2.5 mm, but may also be smaller or larger. On such test adapters, hundreds or thousands, often even tens of thousands or hundreds of thousands of such spring contact pins are often arranged at short lateral distances from one another. The length of such

Spring contact pins are also relatively small and can usually be in the range of about 1.5 to 8 centimeters. In some cases they can also be shorter or longer.

30

In most cases it is particularly useful to form the contact bolt 17 as a single piece. In some cases, however, it may be useful to form its contact head as a separate part which is

35

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H » ( ■ 1 t I

ti ( ·

5860IP-23-

the shaft 16 or the like of the contact bolt is detachably attached or non-detachably attached, e.g. by welding and can thus be made of a different material than the rest of the contact bolt.

The contact head forming the front free end of the contact bolt 18 can also have any other configuration than that shown that is suitable for contacting test objects, for example with several tips, with at least one cutting edge or be designed in some other way. It can

preferably thicker than the shaft that supports it or, in some cases, only as a free, preferably pointed or otherwise shaped end of the shaft.

Preferably, in the case of 2® spring contact pins according to the invention, the base body of the piston 17 has a greater hardness, preferably significantly greater hardness, than the base body of the cylinder 15, which has a beneficial effect on further reducing wear and maintaining low electrical contact resistance. The base body is the body which, in the case of a coating, carries the coating and, in the case of no coating, forms the uncoated piston or cylinder. The difference in hardness between the two base bodies can preferably be at least 50 Vickers.

Claims (1)

IP-1- Protection claims jQ 1. Spring contact pin for test devices for testing electrical, in particular electronic test objects, such as printed circuit boards or the like, which spring contact pin has a metallic cylinder which has an interior space ,g in which the single piston of a Cylinder protruding, spring-loaded metallic contact bolt is slidably mounted, the front, free end of which serves to come into contact with test objects, characterized in that that the at least one sliding surface (24; 24'; 24") of the piston (17) serving for sliding on the track (25; 25') of the cylinder (15) is crowned and ds-ß the contact bolt (18) at least in its front rest position, in the its front end (20) is unloaded and is centered to the cylinder (15). 2. Spring contact pin according to claim 1, characterized characterized in that the convex __. sliding surface or at least one convex designed sliding surface of the piston (17) is formed by a rotationally symmetrical piston surface . _oii 3. Spring contact pin according to claim 1 or 2, characterized OO 5860IP-2- characterized in that the crowned sliding surface or at least one crowned designed sliding surface (24; 24') of the piston (17) is formed by a spherical zone of the contact bolt (18). 4. Spring contact pin according to claim 1 or 2, characterized in that the spherical sliding surface (24") of the piston is formed by a barrel-shaped, ellipsoidal, oval or approximately spherical convex region of the contact bolt is formed.
15 5. Spring contact pin according to one of the preceding claims, characterized in that the piston (17) in the cylinder (15) by means of two axially spaced, spherical formed sliding surfaces (24, 24') are guided straight. 6. Spring contact pin according to one of claims 1-4, characterized in that the piston (17) has a only spherical sliding surface (24*; 24") and the contact bolt can penetrate an opening (40) of the cylinder (15) with such a large lateral play that the contact bolt (18) can be pushed into the cylinder (15) during operation due to the spherical can pivot in all directions transversely to its longitudinal direction for self-centering of its front end in recesses, bushings (35) or the like of test objects (27). ** · · #·#· . s Äseec β-, * IP-3- 7. Spring contact pin according to claim 6, characterized in that the contact bolt (18) in its front rest position is centered in an opening (40) of the cylinder (15) through which it passes and against whose wall it then rests. Claims, characterized in that the piston is solid. 9. Spring contact pin according to one of the preceding Claims, characterized in that the piston IB (17), preferably the contact bolt, is formed in one piece. .Spring contact pin according to one of the preceding claims, characterized in that the contact bolt (18) is rigid or stiff. 11.Spring contact pin according to one of the preceding claims, characterized in that the piston (17) consists of coated or uncoated steel, preferably stainless steel, copper-beryllium or nickel-beryllium, whereby in the case of a coating this preferably consists of galvanically or chemically applied nickel or hard nickel, or of a nickel or hard nickel layer serving as a diffusion barrier and a layer of precious metal applied thereon, preferably of silver, gold, rhodium or palladium, or of a precious metal alloy, preferably a 5860IP-4- Silver, gold, rhodium or palladium alloy can exist.
5 .-ISpring contact pin according to one of the preceding claims, characterized in that the cylinder (15) is made of coated or uncoated steel, brilliance, brass or copper, wherein in the case of a coating of the raceway (25) this is preferably made of galvanically or chemically applied nickel or hardened nickel or of J precious metal or a precious metal alloy or a layer of nickel or hard nickel and a layer based on &idiagr; the layer of precious metal applied to it, preferably silver, gold or palladium, or a precious metal alloy, preferably an I Can consist of silver, gold or palladium alloy. 13. Spring contact pin according to one of the preceding I Claims, characterized in that the base body of the piston (17) of the contact bolt (18) is harder than the base body of the cylinder (15).