Printed circuit board connector

A printed circuit board connector includes contact elements for electrically connecting contacts of at least two electrical printed circuit boards, and retaining devices retaining the contact elements in an intended position inside the printed circuit board connector. The contact elements and the retaining devices are constructed and/or disposed in such a way as to cause forces exerted upon the retaining devices by and/or through the contact elements to at least partly cancel one another out in the region of the retaining devices.

BACKGROUND OF THE INVENTION 
FIELD OF THE INVENTION 
The invention relates to a printed circuit board connector having contact 
elements for electrically connecting contacts of at least two electrical 
printed circuit boards, and having retaining devices that retain the 
contact elements in their intended position inside the printed circuit 
board connector. 
Such printed circuit board connectors are known in great numbers. 
The increasing complexity of printed circuit boards that are to be 
connected necessitates the use of printed circuit board connectors with 
ever higher numbers of poles. Moreover, the demands of quality are 
increasing as well. Such demands include, among others, demands for 
strength and reliability of the electrical connections that can be made by 
the printed circuit board connectors (high contact forces). 
Printed circuit board connectors that meet those demands are being put in 
contact with the printed circuit boards to be connected to one another, 
and in a connection position of those printed circuit boards a not 
inconsiderable force, which necessitates a correspondingly stable 
construction of those elements, is exerted upon the retaining devices that 
keep the contact elements in their intended position within the printed 
circuit board connector, on the printed circuit board connector housing, 
and on the connections between the retaining devices and the contact 
elements as well as between the retaining devices and the printed circuit 
board connector housing. 
However, an especially stable construction of those elements results in an 
increase in their size and is thus contrary to the further demand that the 
printed circuit board connectors be kept as small as possible or be made 
with the highest possible contact element density. 
SUMMARY OF THE INVENTION 
It is accordingly an object of the invention to provide a printed circuit 
board connector, which overcomes the hereinafore-mentioned disadvantages 
of the heretofore-known devices of this general type in such a way that it 
can also be made small and/or with a high contact element density, even in 
a high polarity version and/or in an embodiment used to attain especially 
high contact forces. 
With the foregoing and other objects in view there is provided, in 
accordance with the invention, a printed circuit board connector, 
comprising contact elements for electrically connecting contacts of at 
least two electrical printed circuit boards; and retaining devices 
retaining the contact elements in an intended position inside the printed 
circuit board connector; the contact elements and the retaining devices 
being constructed and/or disposed for causing forces exerted upon the 
retaining devices by and/or through the contact elements to at least 
partly cancel one another out in the region of the retaining devices. 
The provision of a partial cancellation of the forces on the retaining 
devices (for instance through the use of an at least partly symmetrical 
construction of the contact elements relative to the retaining devices) 
has the direct consequence of causing the resultant forces in the region 
of the retaining devices to be considerably lower, so that the stability 
and therefore the size of the retaining devices, the printed circuit board 
connector housing, and the connections between the retaining devices and 
the contact elements and between the retaining devices and the printed 
circuit board connector housing, can be reduced markedly. 
Accordingly, a printed circuit board connector has been created that even 
in a high polarity version and/or in an embodiment for attaining 
especially high contact forces, can be made small and/or with high contact 
element density. 
In accordance with another feature of the invention, the contact elements 
electrically connect parallel printed circuit boards. In accordance with a 
further feature of the invention, the contacts of the electrical printed 
circuit boards are surface contacts. 
In accordance with an added feature of the invention, there are provided 
conduits inside the printed circuit board connector, the contact elements 
being passed through the conduits and having end portions pressed 
elastically back into the conduits in a connection position of the printed 
circuit board connector. In accordance with an additional feature of the 
invention, the conduits and the contact elements have a curved course. In 
accordance with yet another feature of the invention, the retaining 
devices fix the contact elements inside the conduits for securing the 
contact elements against displacement along the conduits. 
In accordance with yet a further feature of the invention, there is 
provided a screw connection for securing the printed circuit board 
connector and the printed circuit boards to one another. 
In accordance with yet an added feature of the invention, there is provided 
a housing having a plurality of individual parts to be guided along one 
another when put together to permit a force-free introduction of the 
contact elements into the conduits. In accordance with yet an additional 
feature of the invention, there is provided a mounting frame for holding 
the individual parts together. In accordance with again another feature of 
the invention, the mounting frame enables an electrical connection of the 
housing to ground contacts on the printed circuit boards, in a connection 
position of the printed circuit board connector. In accordance with a 
concomitant feature of the invention, the housing is electrically 
conductive. 
Other features which are considered as characteristic for the invention are 
set forth in the appended claims. 
Although the invention is illustrated and described herein as embodied in a 
printed circuit board connector, it is nevertheless not intended to be 
limited to the details shown, since various modifications and structural 
changes may be made therein without departing from the spirit of the 
invention and within the scope and range of equivalents of the claims. 
The construction and method of operation of the invention, however, 
together with additional objects and advantages thereof will be best 
understood from the following description of specific embodiments when 
read in connection with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the figures of the drawings in detail and first, 
particularly, to FIG. 1 thereof, there is seen a printed circuit board 
connector which represents a printed circuit board connector according to 
an exemplary embodiment of the present invention and is identified by 
reference numeral 10. In a connection position shown in FIG. 1, the 
printed circuit board connector 10 is disposed (clamped) between first and 
second parallel printed circuit boards 1 and 2, and it is held in this 
position through the use of screws 3 and 4. The printed circuit boards 1 
and 2 are respectively shown as upper and lower printed circuit boards in 
FIG. 1. A first contact strip element 5 is provided between the printed 
circuit board connector 10 and the first printed circuit board 1, and a 
second contact strip element 6 is provided between the printed circuit 
board connector 10 and the second printed circuit board 2. 
A housing of the printed circuit board connector 10 includes a lower part 
11 and two upper parts 12 and 13 seen in FIG. 1. The housing, or the 
components forming the housing, are electrically conductively constructed, 
or in other words are preferably made of metal or a material that contains 
metal. 
Conduits 14 are formed inside the housing of the printed circuit board 
connector 10. The conduits have a curved course as shown in FIG. 1. In the 
connection position shown in FIG. 1, the conduits extend substantially 
continuously from a surface of the first printed circuit board 1 to a 
surface of the second printed circuit board 2. 
An elongated contact element 15 is extended inside each conduit 14 and 
spaced apart from the conduit walls. The elongated contact element 15 can 
electrically connect a contact spot (surface contact) provided on the 
surface of the first printed circuit board 1 to a contact spot (surface 
contact) provided on the surface of the second printed circuit board 2. 
The contact elements 15 are constructed to be elastically bendable, at 
least on their ends. 
As long as the printed circuit board connector is not in the connection 
position shown in FIG. 1, outer ends of the contact elements 15 protrude 
out of the conduits 14 at both sides of the conduits. When the printed 
circuit board connector is moved into the connection position shown in 
FIG. 1, end portions of the contact elements 15 are pressed backward into 
the respective conduits, in the process of the clamping of the printed 
circuit board connector between the first and second electrical printed 
circuit boards. In the connection position of the printed circuit board 
connector, the end portions of the contact elements exert a contact 
pressure force on the contact spots to be contacted on the surfaces of the 
printed circuit boards, and as a result they assure high contact forces, 
or in other words a strong and reliable printed circuit board connection, 
from the surface of one printed circuit board to another. 
The electrical connection of the printed circuit boards solely through 
surface contacts aids in reducing reflection from the connection points 
and thereby enables a considerable lessening of signal distortion, since 
there is no or at least no significant overlap in the current flow 
direction of the elements that effect the electrical connection. Moreover, 
it enables a simpler, more-stable construction of the printed circuit 
boards in the connection region (without any connection holes for 
press-fitting an electrical connector into the printed circuit board). 
In the connection position of the printed circuit board connector, the 
contact elements 15 are substantially surrounded entirely, over their 
entire length, by the walls of the conduits 14. 
Approximately in the middle between the ends of the conduits (at a boundary 
between the lower part 11 and the upper parts 12 and 13 of the housing of 
the printed circuit board connector), each of the contact elements 15 are 
retained by a retaining element 16. The retaining elements 16 are each 
solidly connected to the respective contact elements 15. The retaining 
elements 16 have dimensions that exceed the internal dimensions of the 
respective conduits 14. They are inserted into suitable recesses between 
the lower part 11 and the upper parts 12, 13 of the printed circuit board 
connector housing, in such a way that in the assembled state of the 
printed circuit board connector they are immovably connected to the 
connector. 
The retaining elements 16 (partly in cooperation with the contact elements 
15 retained by them) have multiple functions: First of all, they are 
intended to prevent the contact elements 15 from touching the electrically 
conductive conduit walls. Moreover, they are intended to prevent the 
contact elements from being displaceable along the various conduits. 
Finally, however, they are also intended to enable a defined motion of the 
contact elements inside the conduits (for instance, a motion parallel to a 
conduit wall that defines the impedance, especially when the printed 
circuit board connector is put into its connection position) and to 
preclude other motions, for instance by a suitable cross-sectional 
construction or the like, above all of the contact elements. 
The contact elements 15 are disposed substantially symmetrically with 
respect to the retaining elements 16, at least in their immediate 
vicinity, or are disposed in such a way that the forces exerted on the 
retaining elements 16 by or through the contact elements 15 have a 
substantially symmetrical course with respect to the retaining elements, 
at least in their immediate vicinity. It is possible as a result for the 
forces exerted on the retaining elements 16 by or through the contact 
elements 15 to cancel one another out at least partially in the region of 
the retaining elements 16. The retaining elements 16 themselves, along 
with the printed circuit board connector housing, the connection between 
the retaining elements and the contact elements, and in particular the 
anchoring of the retaining elements in the printed circuit board connector 
housing, as a result may have only a relatively slight stability and be 
correspondingly small, without problems. The printed circuit board 
connector according to the invention can therefore be constructed to be 
relatively small and/or can have a very high contact density (given a 
close-together configuration of the contact elements or rows of contact 
elements, optionally with interesting thereof). 
The contact strip elements 5, 6, as already noted above, are provided 
between the printed circuit board connector and the electrical printed 
circuit boards. These contact strip elements are electrically conductively 
constructed and serve to make an electrical connection between ground 
contacts of the printed circuit boards to be connected to one another. 
However, no separate contact elements 15 are provided in the present 
exemplary embodiment for connecting the ground contacts. Instead, the 
electrical connection between the ground contacts of the various 
electrical printed circuit boards is accomplished by a different kind of 
establishment of a continuous electrical connection path. The connection 
path namely extends from the ground contacts of the first printed circuit 
board 1 through the associated first (electrically conductive) contact 
strip element 5, the (electrically conductive) housing of the printed 
circuit board connector, and the second (electrically conductive) contact 
strip element 6, assigned to the second electrical printed circuit board 
2, to the ground contacts of the second electrical printed circuit board 
2. 
This kind of ground connection has various kinds of advantages. On one 
hand, the number of contact elements 15 to be provided in the printed 
circuit board connector can be reduced quite considerably under some 
circumstances as a result, and on the other hand, the grounding of the 
housing of the printed circuit board connector has the positive effect of 
ensuring that the contact elements 15, extending entirely inside the 
conduits 14, are perfectly shielded from one another over their entire 
length, thus reducing the danger of crosstalk or other mutual influences 
to a minimum. 
In order to enable an assurance between perfect contact-making between the 
ground contacts of the printed circuit boards and the housing of the 
printed circuit board connector, the contact strip elements 5, 6 have 
resilient contact laminations at the top and bottom. The contact strip 
elements have corresponding recesses at those locations where contact 
spots of the printed circuit boards are to be connected to the contact 
elements 15 of the printed circuit board connector. However, many ground 
contacts for which contact can be made by the contact strip elements may 
be provided, particularly in the immediate vicinity of such recesses, that 
is around the conduit openings. 
Two of the possible embodiments of such contact strip elements are shown in 
FIGS. 2a and 2b. In order to illustrate the mode of operation of such 
contact strip elements, the contact strip element shown in FIG. 2b is 
shown in FIG. 2c in a state in which it is fastened between two surfaces 
to be electrically connected to one another. 
The aforementioned contact strip elements 5, 6 are components of a two-part 
mounting frame that is capable of receiving the printed circuit board 
connector inside it. More specifically, the first contact strip element 
forms a top side of a half-shell-shaped first half of the mounting frame, 
and the second contact strip element forms a bottom side of a 
half-shell-shaped second half of the mounting frame. Each of the contact 
strip elements moreover have extensions that form side elements of the 
halves of the mounting frame but that no longer need to have a structure 
of the kind shown in FIGS. 2a and 2b and instead can be structured 
arbitrarily differently. 
Spring tabs 7 are provided on the side parts of the respective halves of 
the mounting frame and can lock in detent fashion in corresponding 
recesses in the housing of the printed circuit board connector. As is 
shown in FIG. 1, the lower half of the mounting frame, in terms of FIG. 1, 
can lock in detent fashion to the top parts 12, 13 of the printed circuit 
board connector housing, and the half of the mounting frame at the top in 
FIG. 1 can lock in detent fashion to the lower part 11 of the printed 
circuit board connector housing. 
The multi-part construction of the printed circuit board connector housing, 
which is shown in FIG. 1, serves to make it simple to put the connector 
together: First, the contact elements 15, with the retaining elements 16 
secured to them, are inserted into the lower part 11 of the printed 
circuit board connector housing or more precisely into the conduit parts 
provided in that portion. They are introduced in such a way that the 
retaining elements 16 come to rest in corresponding recesses on the top of 
the lower part 11 of the printed circuit board connector housing. Once all 
of the conduits 14 have been equipped with contact elements 15, the two 
upper parts 12, 13 of the printed circuit board connector housing are 
placed on the lower part, with these elements initially merely resting 
loosely on one another. 
The placement of the upper parts on the lower part is carried out by an 
obliquely extending placement motion. More specifically, the upper part 12 
on the left in the drawing is put in place through the use of a movement 
from the upper right to the lower left, and the upper part 13 on the right 
in the drawing is put in place through the use of a movement from the top 
left to the bottom right. The extent of the oblique motion depends on the 
shape of the contact elements. In the ideal case, slipping the upper parts 
over the upper half of the contact elements, that is the upper half in 
terms of the drawing, is carried out in such a way that the contact 
elements do not touch the conduit walls at all, or at most only slightly, 
or in other words are substantially parallel to the course of the contact 
elements in the region to be covered. In this way, damage to the conduit 
walls and/or the contact elements during mounting can be maximally 
avoided. Another favorable factor is that not only all of the contact 
elements onto which the upper left part 12 in the drawing is placed but 
also all of the contact elements onto which the upper right part 13 in the 
drawing is placed, extend parallel to one another. The contact elements 
belonging to different groups (to be covered by different upper parts) are 
not constructed in the present exemplary embodiment as parallel but rather 
symmetrical to one another, for the sake of attaining a symmetrical 
distribution of force with respect to the connection of the electrical 
connector to the printed circuit board to be connected, as will be 
described below. 
In order to make quite certain of the aforementioned oblique placement 
motion, the lower part has a protrusion of the kind shown in the drawing, 
with two inclines facing one another, along which the upper parts can be 
guided (can slide downward) as they are placed on the lower part. The 
inclines that are clearly visible in the drawing have a course which is 
essentially parallel to the course of the contact element portions that 
are each to be covered by the associated upper parts. However, the 
inclines need not extend straight as shown in the drawing, but instead 
(preferably with close reliance on the shape of the contact elements) may 
also have any arbitrary other shape (for instance being stairstep-like or 
curved). 
In order to attain an even more precisely defined guidance of the upper 
parts on the guide inclines of the lower part, and therefore an even 
more-perfect guidance of the contact elements inside the conduits when the 
upper parts are placed on the lower part, or more specifically to also 
prevent a lateral offset of the upper parts and lower parts when they are 
placed one another the other, the guide inclines may be provided with 
guide elements, for instance in the form of rails or grooves, that extend 
straight or obliquely or curved on their surface, and which can be engaged 
by suitable complementary elements of the upper parts. 
The above-described embodiment of the components of a multiple-part 
electrical connector can be usefully employed not only in the type of 
printed circuit board connector described herein but also quite generally 
in any kind of electrical connector. Such an embodiment reliably makes it 
possible to put together connector components simply and without force 
while at the same time securing the contact elements of the electrical 
connector. 
The upper parts and lower part are held together through the use of the 
detent locking of the configuration having the mounting frame halves, 
already was explained above. 
In the state in which engagement with the mounting frame has been brought 
about, the printed circuit board connector is prepared for making a 
connection with printed circuit boards that are to be connected to one 
another. 
The connection is made by fasteners, such as the screws 3, 4, of which a 
plurality are disposed in line with one another in the view of FIG. 1 and 
which enter alternatingly from above and from below. 
The alternating fastening of opposed sides of the configuration makes it 
possible to provide a high density of fasteners, which in turn makes it 
possible for even small printed circuit board connectors to be reliably 
firmly connected to the printed circuit boards that are to be connected to 
one another. 
The connection of the elements by screws can be achieved in the most 
various ways (screwing into the printed circuit board connector housing, 
screwing with nuts, screwing a plurality of screw elements in one another 
in interested fashion, and so forth). 
Regardless of the type of fastener, it proves to be advantageous if the 
printed circuit board connector is clamped as uniformly strongly as 
possible between the printed circuit boards to be joined together, with 
the additional interposition of the contact strip elements, because in 
this way on one hand uniformly good connections are obtained, and on the 
other hand the resultant distribution of force to the contact elements 
leads to an improved force compensation in the region of the retaining 
elements 16. 
It may also be worthwhile to construct or select the printed circuit board 
connector and the fastener, or to define the use of these elements, in 
such a way that the connection between the printed circuit board connector 
and the first printed circuit board and the connection between the printed 
circuit board connector and the second printed circuit board, are made 
simultaneously and each to the identical extent. As a result, the 
aforementioned force compensation can already be realized as the printed 
circuit board connector is introduced into its connecting position as well 
as when the printed circuit board connector is released from this 
position. 
The present description has related to a printed circuit board connector 
for transmitting asymmetrical signals (one internal conductor and one 
common outer conductor each). The printed circuit board connector 
described herein, optionally with suitable modification, can also be used 
for transmitting symmetrical signals (two internal conductors). 
In the case where asymmetrical signals are transmitted, that is, if only 
one internal conductor is provided, an impedance of the printed circuit 
board connector is settable by setting (and maintaining) a spacing between 
the internal conductor and an impedance-determining side wall of the 
conduit. 
In the event that symmetrical signals are transmitted, that is, if two 
internal conductors are provided, an impedance of the printed circuit 
board connector can be adjusted by setting (and maintaining) a spacing 
between the two (internal) conductors and by setting a spacing between the 
two internal conductors and an impedance-determining side wall of the 
conduit. 
In order to ensure that an impedance value once set will be kept constant 
under all circumstances, the conduits 14, contact elements 15 and 
retaining elements 16 should be constructed in such a way that the elastic 
motion of the contact elements 15 inside the conduits 14 that takes place 
when the printed circuit board connector is introduced into and/or 
released from its connecting position, is possible solely in directions 
which do not cause any change in impedance (an example being a motion 
parallel to an impedance-determining wall).