Press in contact element for circuit boards

A contact element has an improved press in zone which is formed by two leg members extending substantially parallel to one another with an interconnecting web. The improvement is that the web is broken up into portions with adjacent portions having curvatures that extend in opposite directions to increase the strength of the press in zone and provides an optimally uniform, symmetrical pressure distribution between a bore wall and the press in zone of the contact element when the press in zone is plugged into a bore of a printed circuit board.

BACKGROUND OF THE INVENTION 
The present invention is directed to a contact element that comprises a 
pin-shaped section equipped for plugging into a bore of a printed circuit 
board. The pin-shaped section has two leg members that extend side-by-side 
in the plug-in direction and merge into one another at each end to provide 
a resilient section with at least one web extending between the leg 
members and having a central curvature or angling which is directed 
transverse relative to the longitudinal extent of the leg members. 
U.S. Pat. No. 4,762,498, whose disclosure is incorporated by reference and 
which is based on the same German Application as European Patent No. 0 089 
491, discloses a contact element which has two spaced leg members 
interconnected by a web that extends therebetween. The two spaced leg 
members with the web extending therebetween of this contact element 
promotes the resilient yielding of the leg members and, thereby, reduces 
the risk of too great and irreversible deformation of the leg members when 
plugging the contact element into a bore of a printed circuit board. As a 
result thereof, a permanent, firm seat of the leg members, which are 
biased against the bore's wall, is guaranteed. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to construct a contact element of 
the above type species in such a way that the symmetrical absorption of 
the forces which the leg members exert on the wall of the bore by the web 
connecting the leg members is further improved. 
This object is inventively achieved in an improvement in a contact element 
which comprises a pin-shaped section provided for being plugged into a 
bore of a printed circuit board, said pin-shaped section having two leg 
members extending side-by-side in a longitudinal plug-in direction and 
merging into one another at their ends, to form transition zones and a 
resilient section with a web extending between the leg members and having 
a central curvature or angling directed transversely relative to the 
longitudinal extent of the leg members. The improvements are that the web 
is divided into at least two parts, one following another in the plug-in 
direction, the central curvature or angling of adjacent web portions being 
in opposite directions. 
By employing, for example, a web with four portions, wherein two are angled 
off to one side of the element and two are directed toward the opposite 
side of the element, an especially uniform distribution of forces occurs 
in the region of the press in zone or resilient section of the contact 
element defined by the length of the leg members. 
In another modification of the invention, the wall thickness of the web 
portion is reduced as the distance from the leg members increases so that 
the central part of each web portion has the least thickness. 
It can also be provided that the transition zones are web-free. As a result 
thereof, the transition zones are more elastic. It is also possible that 
triangle-shaped webs are provided in the region of the transition zone of 
the leg members. A central curvature or angling of these triangle-shaped 
webs is increasingly enlarged towards a neighboring web. The result is 
that an especially resistant press in zone is obtained. 
In a further embodiment of the invention, the wall thickness of a 
triangle-shaped web toward a neighboring web is reduced from the thickness 
of the leg members to the thickness of the web of the neighboring web. 
It can also be provided that the surfaces of the leg members facing toward 
one another extend parallel to one another and that the outside surfaces 
of the leg members which face away from one another extend in an acute 
angle in the plug-in direction of the contact element. This will 
facilitate the insertion of the press in zone into a bore of the printed 
circuit board. 
It can also be provided that the leg members are provided with a rounding 
on an outer surface, which rounding is matched to the curvature of the 
bore. A result of this rounding is good contact of the leg members to the 
board of the printed circuit board. 
Finally, neighboring webs are interconnected via partitions that are thin 
in comparison to the wall thickness of the webs and that said partitions 
are essentially directed transversely to the axis of the element and the 
longitudinal direction of the leg members. The result is that the webs are 
mutually supported via these partitions or walls. 
Other advantages and features of the invention will be readily apparent 
from the following description of the preferred embodiments, the drawings 
and claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The principles of the present invention are particularly useful when 
incorporated in a contact element which has a section, generally indicated 
at 1, that forms an elastic or resilient press in zone which fixes the 
contact element solder-free in a bore of a printed circuit board. As 
illustrated in FIGS. 1 and 3, the section 1 is formed by two leg members 2 
which proceed side-by-side and are spaced from one another by a plurality 
of wall-like web portions 3 and 3' which have their flat sides 4 and 4' 
proceeding parallel to a longitudinal axis 5 of the contact element. As 
illustrated in FIG. 2, the web portions 3 are interconnected alternately 
with the web portions 3' along the axis of the contact element in the 
direction of which the leg members run. Thus, the elastic press in zone is 
formed by the two leg members 2 with the web portions 3 and 3' extending 
therebetween. 
The web portions 3 and 3' are angled respectively curved transversely 
relative to the longitudinal direction of the leg members 2. The direction 
of curvature or respective angling of the portions follows one another in 
the longitudinal direction of the leg members 2 respectively in opposite 
directions. Thus, as illustrated in FIG. 2, the web portions 3 all extend 
to the right side, whereas the web portions 3' extend to the left side. 
When producing the angled or, respectively, curved curvatures of the web 
portions 3 and 3', partitions 6, which extend substantially transverse 
relative to the longitudinal axis 5 of the press in zone and have a wall 
thickness that is significantly smaller than that of the web portions 3 
and 3' remain between the neighboring web portions 3 and 3', which are 
interconnected by these partitions 6. The stability of the web portions 3 
and 3' is thereby increased. 
As particularly illustrated in FIG. 3, the wall thickness of the web 
portion 3, as well as the wall thickness of the web portion 3' are 
significantly less than the wall thickness of the beam-shaped leg members 
2 and is reduced as the distance from the leg members increases so that a 
center of each of the portions at the center 12 of curvature for the web 
portions will be thinner than the web adjacent each of the leg members 2. 
This structure achieves a progressively increasing supporting effect of 
the portions 3 with respect to the leg members 2. 
As illustrated in FIG. 1, the leg members 2 merge with one another at each 
of their two ends and form triangular transition zones 7 therebetween. At 
one end of the press in zone formed by the section 1 of the contact 
element, the leg members 2 merge into one another and form, for example, a 
pin that projects out of the bore on one side of the printed circuit board 
(not shown) in which the contact element is seated with the press in zone 
and this pin can be used as a supporting point for the connection of 
conductors or as a contact pin or contact blade for plugging a contact 
spring on. At the other end, the leg members 2 merge into one another and 
form a shoulder 8 that limits the insertion depth of the press in zone in 
a bore of the printed circuit board. 
As illustrated in the embodiments of FIGS. 1, 2 and 3, the transition zones 
or regions 7 are provided with triangle-shaped webs 9 which are curved to 
extend in an opposite direction to the nearest web portion and these 
triangle-shaped portions have continuously reduced thickness as a distance 
from the neighboring leg members 2 decreases in a manner similar to that 
of the web portions 3 and 3'. 
In a modification illustrated in FIGS. 4 and 6, the wall thickness of each 
of the triangle-shaped webs 9' diminishes towards the neighboring web 
portions 3 or 3' from the thickness of the leg members 2 to the thickness 
of the portions 3 or 3'. 
In an embodiment illustrated in FIG. 5, each of the regions or zones 7 is 
free of any material so that there is an opening adjacent the apex of the 
merging leg members. 
It is also advantageous to maintain the parallelism of the inner lateral 
faces or surfaces 10 of the leg members 2 which face one another and to 
have the outside faces or surfaces 11, which face away from one another, 
proceeding conically and interacting with one another. Thus, the two 
outside surfaces 11, as illustrated in FIG. 6, form a slight acute angle 
as they taper slightly inward from adjacent the shoulder 8 towards the end 
forming the pin of the contact element. This slight inward taper will help 
facilitate the insertion of the contact element into a printed circuit 
board and enable the pressing of the press in zone 1 into the bore. It 
should also be noted, as illustrated in FIG. 3, the outer edges of the leg 
members 2 can have a curved configuration, either as illustrated or with 
an overall curvature between the two corners to facilitate forming a 
contact with the surface of the bore. 
Although various minor modifications may be suggested by those versed in 
the art, it should be understood that we wish to embody within the scope 
of the patent granted hereon all such modifications as reasonably and 
properly come within the scope of our contribution to the art.