Snap lock membrane connector

A device that allows for simple cost effective connections to flexible multilayered circuits and flexible membrane switches. The invention provides a connecting device that includes a housing that has a base and a closeable lid. At least one contact is attached to the housing. One end of the contact(s) extends beyond the housing and is suitable for making a connection to an electrical circuit. The other end of the contact(s) is positioned inside the housing for connecting to the flexible circuit board or flexible membrane. The lid can be fixed in the closed position whereby the end of the contact(s) inside the housing is compressed with the flexible circuit. The lid can be attached to the base with a hinge, and when the lid is closed it snap locks in place so that the contact(s) are firmly held to the conductive pads of flexible circuit. The membrane or flexible circuit is quickly and accurately positioned in place and securely held by using tabs on the housing which protrude through slots in the membrane or flexible circuit.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention generally relates to the art of electrical connectors and, 
particularly, to a connector with a locking housing for connecting 
flexible circuits or membranes having internal electrical traces to 
another electrical circuit. 
2. Description of the Related Art 
Various devices are known for making an electrical connection to flexible 
circuit board. If a single layered flexible circuit board is used then it 
typically will have electrical traces attached to conductive pads. On a 
single layered pad, the traces and conductive pads will be exposed to the 
surface. Connections to these pads may be made similar to ordinary 
non-flexible circuit boards, such as using spring biased contact members. 
Connection to flexible circuit boards becomes more difficult, if the boards 
are stacked or layered together. Connection to exposed traces and 
conductive pads can be done in the same manner as for single layered 
boards, but connecting to electrical layers sandwiched between two or more 
boards requires a different approach since the conductive pads are not 
exposed to the surface. Similar considerations must also be made for 
flexible membrane switches, which have electrical conductors formed on the 
inside surfaces of two mating dielectric films. 
One method of making connections to non-exposed electrical circuits is to 
drill holes or vias through the circuit board or dielectric film and fill 
the vias with a conductive material. Through the vias, electrical 
terminations that are not exposed can be routed to surfaces that are 
exposed and then connected in traditional manners. Additional traces and 
conductive pads may be placed on the exposed surface to properly connect 
the circuits routed through the vias. The problem with this approach is 
the increased complexity of manufacturing and associated costs. 
Another approach to connecting the internal circuits is to cut one or more 
of the outside circuit boards or dielectric films short. In this way, the 
internal conductive pads can be exposed since they will project beyond the 
opposing circuit board that covers the majority of the circuit to be 
connected. Several layers of circuits can be connected in this manner as 
each consecutive layer is cut back a little further as in a step-like 
manner. This method has shortcomings also since it poses additional 
considerations of connecting to circuits on the bottom side of a cut back 
layer. 
3. Related Art 
Examples of patents that are related to the present invention are as 
follows, and each patent is herein incorporated by reference for the 
supporting teachings: 
U.S. Pat. No. 5,205,741 is a connector assembly for testing integrated 
circuit packages. 
U.S. Pat. No. 5,248,262 is a high density connector. 
U.S. Pat. No. 5,269,705 is a tape filter and method of applying same to an 
electrical connector. 
U.S. Pat. No. 5,277,611 is an arrangement for connecting an electrical 
connector to a printed circuit board. 
U.S. Pat. No. 5,278,725 is a foldable electronic apparatus having a hollow 
hinge assembly through which a flexible cable is routed. 
U.S. Pat. No. 5,295,838 has raised feature gold dot pressure 
interconnections of rigid- flex circuits and rigid circuit boards. 
U.S. Pat. No. 5,433,632 is a flexible circuit connector. 
U.S. Pat. No. 5,509,827 is a high density, high bandwidth coaxial cable, 
flexible circuit and circuit board connection assembly. 
The foregoing patents reflect the state of the art of which the applicant 
is aware and are tendered with the view toward discharging applicant's 
acknowledged duty of candor in disclosing information which may be 
pertinent in the examination of this application. It is respectfully 
stipulated, however, that none of these patents teach or render obvious, 
singly or when considered in combination, applicant's claimed invention. 
SUMMARY OF THE INVENTION 
It is a feature of the invention to provide a device that allows for simple 
cost effective connections to flexible multilayered circuits and flexible 
membrane switches. 
An additional feature of the invention is to provide a connecting device 
that includes a housing that has a base and a closeable lid. At least one 
contact is attached to the housing. One end of the contact(s) extends 
beyond the housing and is suitable for making a connection to an 
electrical circuit. The other end of the contact(s) is positioned inside 
the housing for connecting to the flexible circuit board or flexible 
membrane. The lid can be fixed in the closed position whereby the end of 
the contact(s) inside the housing is compressed with the flexible circuit. 
Another feature of the invention is to have the lid attached to the base 
with a hinge, and when the lid is closed it snap locks in place so that 
the contact(s) are firmly held to the conductive pads of flexible circuit. 
A further feature of the invention is to provide a device that quickly and 
accurately positions the membrane or flexible circuit in place and 
securely hold it by using tabs on the housing which protrude through slots 
in the membrane or flexible circuit. 
The invention resides not in any one of these features per se, but rather 
in the particular combination of all of them herein disclosed and claimed 
and it is distinguished from the prior art in this particular combination 
of all of its structures for the functions specified. 
There has thus been outlined, rather broadly, the more important features 
of the invention in order that the detailed description thereof that 
follows may be better understood, and in order that the present 
contribution to the art may be better appreciated. There are, of course, 
additional features of the invention that will be described hereinafter 
and which will form the subject matter of the claims appended hereto. 
Those skilled in the art will appreciate that the conception, upon which 
this disclosure is based, may readily be utilized as a basis for the 
designing of other structures, methods and systems for carrying out the 
several purposes of the present invention. I t is important, therefore, 
that the claims be regarded as including such equivalent constructions 
insofar as they do not depart from the spirit and scope of the present 
invention. 
Other features of the present invention will become more clear from the 
following detailed description of the invention, taken in conjunction with 
the accompanying drawings and claims, or may be learned by the practice of 
the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention provides a snap lock membrane connector for 
connecting multi-layered flexible circuits or flexible membrane films to a 
device such as a printed circuit board. Referring to FIG. 1, there is a 
snap lock membrane connector 10 depicted in an exploded view with a 
flexible membrane 50. Connector 10 includes a housing 20 having a base 22 
and a lid 30. The housing is made of a dielectric material such as molded 
plastic. The lid 30 is attached to the base 22 by means of a hinge 25. The 
base 22 contains a cavity 28. Attached to the base 22 are fingers 23 that 
project into cavity 28. Lid 30 also contains a cavity 38, and attached to 
lid 30 is another set of fingers 33 that project into cavity 38. Fingers 
23 and 33 form a compression means after closing the cover. The fingers 23 
on base 22 oppose the fingers 33 on lid 30 when lid 30 is closed. The 
preferred embodiment also has tabs 26 on a front side of the base 22 and 
tabs 24 on the sides of base 22. When the connector is assembled, tabs 26 
fit through slots 56 of flexible membrane 50 to both position the membrane 
and help hold it in place. The tabs 26 and slots 56 form major portions of 
a positioning means. When lid 30 is closed, tabs 26 fit into notches or 
indentions 36 located on the front of the lid. Similarly, tabs 24 fit into 
notches or indentations 34 located on the sides of lid 30. Tabs 24 and 26 
and notches or indentions 34 and 36 form a locking means. 
Flexible membrane 50 may comprise two opposing sheets of Mylar film 52 and 
54 or any other flexible circuit board material. Slots 56 extend through 
both film sheets 52 and 54. At least one of the opposing inner surfaces 53 
and 55 of film 52 and 54 respectively has electrical traces 59 placed 
thereon. The traces can be applied in any manner customary in the industry 
such as by employing thick or thin film techniques. At the end of membrane 
50, traces 59 may be terminated with conductive pads 58 for making 
electrical connections thereto. Furthermore, at the end of membrane 50 
where conductive pads 58 are located, the films 52 and 54 are not joined 
together. A space is left between films 52 and 54 so that contact terminal 
ends 42 may be placed in electrical contact with conductive pads 58. 
Regarding FIG. 2, opposite contact ends 44 extend beyond the rear face of 
housing 20 to allow for external electrical connection to another circuit, 
such as a circuit board. Contact members 40 may be insert molded into 
housing 20 or held in place in holes placed through the housing by other 
suitable means such as epoxy. When lid 30 is closed, lips 27 on tabs 24 
and 26 cause the housing to snap lock shut. 
As shown in the cross sectional view of FIG. 3, when lid 30 is closed, 
fingers 23 and 33 act as biased pressure springs to firmly hold terminal 
ends 42 to contact pads 58 between membrane films 52 and 54. Fingers 23 
and 33 may have rounded protrusions 29 and 39 in order to better hold 
terminal end 42 between films 52 and 54. 
Remarks About the Preferred Embodiment 
One of ordinary skill in the art of designing and using connectors for 
flexible membranes or circuits will realize many advantages from using the 
preferred embodiment. For example, the invention provides a quick and 
inexpensive way to make electrical connections to a flexible circuit. A 
skilled artisan will also realize that the invention makes preparation of 
the flexible circuit for making connections much easier than previous 
methods since no vias are required, and extra traces or pads do not need 
to be provided on the outside of the film. Additionally, it is not 
necessary to cut or step back any of the layers of the flexible circuit 
board. 
An additional advantage of the invention is that it is easily adapted to 
different configurations of flexible circuits, and the number, shape, and 
arrangement of the contacts can be varied as desired. 
Variations of the Preferred Embodiment 
Although the illustrated embodiments depict an arrangement of two films 
forming a membrane the preferred embodiment will work for multiple 
arrangements. For example, the invention will work with more than two 
layers of flexible circuits. Additionally, although the preferred 
embodiment discusses the use of pressure spring fingers extending into 
cavities of the housing lid and base, one skilled in the art will realize 
that there are other ways to hold the contacts between the flexible 
membrane. For example, protrusions 29 and 39 could be integrally formed in 
either one or both of the lid and base instead of using the biased 
pressure spring fingers. Screws or epoxy could also be used to hold the 
contacts in the membrane. 
It is also contemplated to design the snap lock mechanism differently than 
the present tabs 24 and 26 and indentations 34 and 36 and still be within 
the scope of the invention. For example, it is equally likely that holes 
be placed in the lid and projections located on the base could extend 
through the holes. Another alternative would be to place the tabs 24 and 
26 on lid 30 and the indentations 34 and 36 on base 22. 
Another feature that could be changed without departing from the scope of 
the invention, would be to eliminate the slots in the film or to place 
notches at the sides of the film. Also, the lid could be totally separate 
from the base instead of being attached by hinges. Furthermore, the 
housing could even have a one piece design so that the flexible film is 
inserted into it. 
While the invention has been taught with specific reference to these 
embodiments, someone skilled in the art will recognize that changes can be 
made in form and detail as discussed without departing from the spirit and 
the scope of the invention. The described embodiments are to be considered 
in all respects only as illustrative and not restrictive. The scope of the 
invention is, therefore, indicated by the appended claims rather than by 
the foregoing description. All changes which come within the meaning and 
range of equivalency of the claims are to be embraced within their scope.