U.S. patent number 3,848,952 [Application Number 05/383,365] was granted by the patent office on 1974-11-19 for zero insertion force edge card connector.
This patent grant is currently assigned to AMP Incorporated. Invention is credited to Charles I. Tighe, Jr..
United States Patent |
3,848,952 |
Tighe, Jr. |
November 19, 1974 |
ZERO INSERTION FORCE EDGE CARD CONNECTOR
Abstract
A zero insertion force electrical connector is disclosed for use
in making edge connections with printed circuit boards and the
like. The subject connector includes a plurality of connector
spring contacts mounted in an associated housing. The housing and a
printed circuit board support are fixedly mounted on a base or
chassis in spaced relationship. The spring contacts are so arranged
as to have a vertical and horizontal cantilever spring components
thus providing for contact adjustment in both the X and Y
directions while providing a high contact force.
Inventors: |
Tighe, Jr.; Charles I. (Camp
Hill, PA) |
Assignee: |
AMP Incorporated (Harrisburg,
PA)
|
Family
ID: |
23512782 |
Appl.
No.: |
05/383,365 |
Filed: |
July 27, 1973 |
Current U.S.
Class: |
439/326 |
Current CPC
Class: |
H01R
12/83 (20130101) |
Current International
Class: |
H01R
12/16 (20060101); H01R 12/00 (20060101); H01r
013/54 () |
Field of
Search: |
;339/64-66,75,91,125,126,176,258 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1,576,555 |
|
Aug 1969 |
|
FR |
|
1,129,580 |
|
May 1962 |
|
DT |
|
1,392,205 |
|
Feb 1965 |
|
FR |
|
Primary Examiner: McGlynn; Joseph H.
Claims
What is claimed is:
1. An electrical connector for receiving and contacting a mating
electrical connector upon application of substantially no insertion
force, comprising:
a housing having a fulcrum portion and a stop portion in parallel
spaced relation defining an access opening therebetween; and
a plurality of connector spring contacts fixedly mounted in said
housing, each said contact including a yoke portion having two
interconnected parallel arms with an electrical contact on one of
said arms and a follower contact on the other of said arms, a
horizontal cantilever spring and a vertical cantilever spring
connected in series, a contact support portion connected to one end
of said spring series and said yoke connected to the other end of
said spring series, and a terminal portion connected to said
contact support, said support portion being fixedly mounted in said
housing with said terminal portion extending from said housing and
said yoke aligned with said access opening, whereby said mating
connector is inserted into said access opening without engaging
said spring contacts and is rotated about said fulcrum portion to
abut said stop portion and engage said spring contacts.
2. An electrical connector according to claim 1 wherein said
housing is formed from an electrical insulation material.
3. An electrical connector according to claim 1 wherein said
housing further comprises registration means at least at one end of
said access opening adapted to align said mating connector.
4. The electrical connector according to claim 1 wherein said
horizontal cantilever spring is connected to said support portion
and said yoke portion is connected to said vertical cantilever
spring and positioned to open vertically to receive vertically
disposed mating connectors.
5. The electrical connector according to claim 1 wherein said
vertical cantilever spring is connected to said support portion and
said yoke portion is connected to said horizontal cantilever spring
and positioned to open horizontally to receive horizontally
disposed mating connectors.
6. The electrical connector according to claim 1 wherein said
mating connector is a printed circuit board, said electrical
contacts on each of said spring contacts engaging with edge contact
pads of said board.
7. The electrical connector assembly according to claim 1 wherein
said mating connector is a male plug.
8. An electrical connector according to claim 1 wherein said
housing further comprises mounting means for attaching said housing
to a support base.
9. An electrical connector according to claim 4 wherein said
mounting means comprises resilient feet adapted to snap fit within
openings in said support base.
10. An electrical connector according to claim 8 wherein said
mounting means comprises outwardly directed flange portions having
openings therein adapted to receive means to secure said housing to
said support base.
11. An electrical connector according to claim 8 further comprising
support means fixed to said support base spaced from said housing
and adapted to engage said mating connector.
12. An electrical connector according to claim 11 wherein said
support means is formed of a resilient material and includes a
support base mounting groove, a mating connector mounting groove, a
stand-off portion between said grooves and a pull tab whereby said
support means is stretched to pass through an opening in said
mating connector and released to hold said mating connector in a
relatively fixed position with respect to said housing and said
support base.
13. An electrical connector system requiring substantially zero
insertion force for receiving and contacting mating electrical
connector, such as a printed circuit board, comprising:
a support base;
a housing having a fulcrum portion and a stop portion in parallel
spaced relation defining an access opening therebetween and
registration means at least at one end of said opening, said
housing fixedly mounted on said support base;
a plurality of connector spring contacts mounted in said housing,
each said contact including a U-shaped yoke portion having an
electrical contact point on one arm and a follower contact point on
the other arm, a support portion adapted to engage the housing,
serially connected horizontal and vertical cantilever springs
connected between said support portion and said yoke portion and
arranged to position said yoke portion to open towards said access
opening, and a terminal portion connected to said support portion
and extending from said housing; and
support means mounted on said support base spaced from said housing
and adapted to releasably engage said mating electrical connector,
whereby a contact bearing edge portion of said mating connector is
inserted into said opening without engaging said contacts and
subsequently pivoted about said fulcrum portion until engaging said
contacts and abutting said stop portion and is secured in said last
mentioned position by engagement with said support means.
Description
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The present invention relates to a zero insertion force electrical
connector for making edge connection with printed circuit boards
and the like and, in particular, to an electrical connector which
may be used with either horizontally or vertically disposed printed
circuit boards.
2. Description of the Prior Art
It is important for any edge board electrical connector to have the
capability of making good electrical contact over a relatively
large range of tolerances. For example, the connector must be able
to accept printed circuit boards which are either warped or have
edge pads which vary in thickness. It is also desirable to have
such a connector arranged to accept printed circuit boards with a
zero insertion force in order to have low wear of both the contacts
and the pads.
Many attempts have been made to provide an electrical connector
having the above properties. For example, U.S. Pat. No. 3,366,919
discloses an electrical connector which requires a low insertion
force. The disclosed connector is arranged to accept the male plug
of a multi-conductor cable at an angle with respect to the
longitudinal axis of the receptacle body. The conductor members of
the cable are initially positioned between the parallel arms of the
receptacle contacts, with low insertion force, and then rotated
into alignment with the axis of the receptacle body after the
contact engage. While this arrangement may prove suitable in some
cases, this connector has a relatively low tolerance range defined
by the amount of resiliency of only one of the two parallel
arms.
U.S. Pat. No. 3,732,531 shows an electrical contact which is
movable in order to provide proper contact with a mating connector.
This connector is intended for use in making contact with printed
circuit boards and has U-shaped arms joined to a base by a
resilient beam. The arrangement is a modification of a cantilever
beam contact and has only limited tolerance for reception of
contact cards which are warped or have pads of varying degrees of
thickness.
SUMMARY OF THE INVENTION
The subject zero insertion force electrical connector includes a
housing having therein a plurality of connector spring contacts
adapted to engage an edge portion of a printed circuit board or the
like. The housing and a printed circuit board support are fixedly
mounted on a base in spaced relationship. Each spring contact
includes a yoke portion having an electrical contact point and a
follower contact, a vertical cantilever spring and a horizontal
cantilever spring connected in series to support the yoke portion,
a contact support section connected to the springs and including
retaining barbs for fixation in the housing, and an electrical
interface terminal projecting from the support section. Each
housing includes a fulcrum, stop and registration guide for the
printed circuit board, a plurality of contact cavities and guides,
and connector mounting brackets extending from a structural frame.
Each printed circuit board support is formed from a resilient
material and includes a support mounting groove, a board mounting
groove, a stand-off section, and a pull tab.
It is an object of the present invention to construct an electrical
connector for making electrical contact with an edge portion of a
printed circuit board or the like which connector will require
substantially zero insertion force and provide a high contact
force.
It is also an object of the present invention to construct a zero
insertion force electrical connector which will have a wide range
of tolerance for accepting printed circuit boards and the like
which are warped and/or have edge contact pads of varying degrees
of thickness.
It is a further object of the present invention to construct a zero
insertion force electrical connector having a plurality of spring
contacts with resiliency in two dimensions thus allowing for making
good electrical contact with printed circuit boards having edge
pads falling within a wide range of tolerances.
It is yet another object of the present invention to construct a
zero insertion force electrical connector which may be used with
either horizontally or vertically disposed printed circuit boards
and the like.
It is still another object of the present invention to construct a
zero insertion force electrical connector which may be readily and
economically produced.
The foregoing and other objects and advantages of the present
invention will become apparent to those skilled in the art from the
following detailed description taken with reference to the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view, partially in section, showing a first
embodiment of the spring contact for subject zero insertion force
electrical connector;
FIG. 2 is a vertical section through the subject zero insertion
force electrical connector showing a second embodiment of the
spring contact, which embodiment is suitable for use with
horizontally disposed printed circuit boards;
FIG. 3 is a vertical section through the subject zero insertion
force electrical connector showing a third embodiment of the spring
contact, which embodiment suitable for use with vertically disposed
printed circuit boards;
FIG. 4 is a schematic representation of a section through a warped
printed circuit board showing the ability of the subject connector
for making good connections over a wide range of tolerance;
FIG. 5 is a perspective view of an end portion of the housing for
the subject zero insertion force electrical connector; and
FIG. 6 is a vertical section through the housing of the subject
zero insertion force electrical connector.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The subject zero insertion force connector system shown in FIG. 1
includes a housing 10 attached to a support base or chassis 12 and
enclosing therein a plurality of first embodiment connector spring
contacts 14. A printed circuit board support member 16 is fixedly
mounted on the base 12 spaced from the housing 10. A printed
circuit board or card 18 is shown mounted in the connector and on
the support member 16. Each first embodiment spring contact 14
includes a yoke portion 20 having an electrical contact 22 which is
substantially parallel to and spaced from a follower contact 24.
The yoke portion 20 is supported by a vertical cantilever spring 26
and a horizontal cantilever spring 28 which extend serially from a
contact support section 30. The contact support section 30 has at
least one retaining barb 32 projecting therefrom for securing the
spring contact in the housing 10. A first electrical interface
terminal 34 depends downwardly from the support section 30 while a
second terminal 36 projects through a rear wall of the housing
10.
The printed circuit board support member 16 is formed from a
unitary piece of resilient material and includes a support mounting
groove 38, a board mounting groove 40 a stand-off section 42 and a
pull tab 44. Each printed circuit board or card 18 to be mounted in
the connector is provided with an opening 46 spaced from the
contact edge and adapted to receive the support member therein.
The housing 10, as best seen in FIGS. 5 and 6, includes a support
frame 48 having a printed circuit board fulcrum portion 50 spaced
above and to the rear of a printed circuit board stop portion 52
defining an elongated access opening 54 therebetween. A plurality
of spring contact guide surfaces 56 and terminal openings 58 are
formed in the housing 10 in parallel spaced relation. A printed
circuit board registration guide panel 60 is formed at each end of
slot 54. The housing is also provided with connector mounting means
62.
The second embodiment of spring contact for the subject connector
is shown in FIG. 2 and is used with horizontally disposed printed
circuit boards. The same reference numerals have been used to
identify like parts of each of the connector spring contact
embodiments. This embodiment includes a yoke 20, an electrical
contact point 22, a follower contact 24, a vertical cantilever
spring 26, a horizontal cantilever spring 28, contact support
section 30, a retaining barb 32 and an electrical interface
terminal 34. The printed circuit board 18 is shown in phantom at
the angle of approach necessary for effecting a zero force
entry.
The third embodiment of spring contact for the subject connector is
shown in FIG. 3 and is used with vertically disposed printed
circuit boards. This embodiment also includes a yoke 20, an
electrical contact point 22, a follower contact point 24, a
vertical cantilever spring 26, a horizontal cantilever spring 28, a
contact support 30, a barb 32 and an electrical interface terminal
34.
The components of the subject connector are assembled by inserting
the terminal and support portions 34 and 30, respectively, of each
spring contact 14 into the associated terminal opening 58 of the
housing 10 until the barb 32 engages in the housing. The assembled
connector is secured to an appropriate support base 12, for example
by snapping mounting feet 62 into holes in the support base or by
soldering the interface terminals to a parent printed circuit
board. The printed circuit board supports 16 are assembled on the
support base 12 and the connecting system is ready to receive a
printed circuit board or card 18. The edge of the printed circuit
board carrying the contact pads is inserted into the connector at
such an angle as to clear both contact points of the spring
contacts 14 and the housing portions 50 and 52 to effect a zero
force entry. Then the printed circuit board 18 is rotated about
fulcrum 50 until the opposite end of the board engages and is
secured by the support member 16.
The contact support section 30 of each connector spring contact 14
serves to retain the contact in the housing 10 and also serves to
mechanically isolate the yoke portion 20 from the interface
terminal 34. The horizontal cantilever spring 28 supplies part of
the contact force and imparts vertical motion to the yoke when
deflected. The vertical cantilever spring 26 supplies the remaining
portion of the contact force and imparts horizontal motion to the
yoke when deflected. Both springs also serve to support the yoke 20
and each other. The yoke 20 includes the follower contact 24 and
the electrical contact 22 which provides both mechanical and
electrical interfacing with the printed circuit board 18. Since the
yoke 20 is a rigid member compared to the spring portions 26, 28 of
the contact, the yoke experiences little or no deflection when a
force is applied to the electrical contact point but rather
transforms the force into components of vertical and horizontal
deflection of the cantilever springs. Therefore, due to this design
characteristic, it is possible to move the yoke 20 in either the X
or Y direction, a resultant direction of X and Y, and even a
rotational motion all but limited to one plane. This motion allows
the yoke to assume any position in a region in the plane of motion
and the vertical distance between the contact points can vary
within this region. Furthermore, as a result of these motions,
relative to displacement of the electrical contact 22 to the
printed circuit board pad occurs to effect contact wiping.
The electrical contact 22 and follower contact 24 are displaced
from each other both vertically and horizontally. This displacement
controls the maximum thickness printed circuit board the yoke will
accept without deflection, while the vertical displacement alone
controls the minimum thickness of printed circuit board that will
take up all of the contact pre-travel. By proper selection of the
sizes for vertical and horizontal displacement, the printed circuit
board thickness limit can be accomodated, while the yoke will not
experience any dimensional change. Additional functions of the yoke
will be discussed later with the housing as an assembled connector.
The only design limitation on the electrical interface terminal is
dependent upon the type of termination specified, i.e., wire wrap,
solder in-printed circuit boards, soldered wire, etc.
The function of the housing portions are evident from their
nomenclature and need little explanation. The printed circuit board
fulcrum provides one of the reaction forces opposing the contact
force and vertically positions the blade end of the printed circuit
board assembly relative to the connector mounting plane. When a
contact is assembled into a housing, the yoke follower contact is
positioned with respect to the fulcrum so as to establish the
contact pre-load. When a printed circuit board is inserted and
rotated into full contact location, the follower contact will be
moved down and coincide with the fulcrum. Any further rotation or
downward motion of the printed circuit board will rotate the yoke,
thereby increasing the contact pressure.
In the case of a printed circuit board which is warped between
contact pads, see FIG. 4, since the yokes capture the board blade
upon insertion and each yoke operates independently, the yokes must
remain in proper contact with the board by departing from their
normal contact position through deflection of the horizontal and
vertical cantilever springs.
The subject connector is not limited to interfacing with a printed
circuit board or card. A plug with a mating contacts may be used in
place of the board and then permanent interface may be made to the
printed circuit board or other devices. The present system uses
motion of the printed circuit board to develop the contact pressure
while the housing in contacts remain fixed. In other design
situations motion of the housing or contacts or both could be used
for this purpose. The contacts alone can be inserted into a mount
surface to make an interface.
FIG. 4 shows a transverse section of a warped printed circuit board
to schematically illustrate how the yoke portions of the contact
springs may be displaced from their normal positioning and still
make full or proper contact with the pads of the printed circuit
board. It should also be noted that the pads are shown with at
least one pad having a greater thickness and yet still making
proper contact with the electrical contact portion of the yoke.
It should be noted that the pivotal movement of the printed circuit
board from the initial entry position to the final fixed position
will cause a certain amount of wipe by the electrical contact point
against the pad on the printed circuit board. Thus the subject
connector will provide a good electrical contact between the board
and the connector system.
The spring contacts can be blanked from any desirable metal. The
blanked contacts will normally have a somewhat roughened surface
and a chisel shape, in transverse section, which will aid with the
above mentioned wiping to produce a good electrical interface
between the contact and the printed circuit board pad.
The subject connector has many advantages including the fact that
there is zero insertion force of the printed circuit board. The
connector can accept a wide range of printed circuit board
thicknesses. Each contact yoke has an additional vertical float in
its cavity which compensates for irregularities in printed circuit
board contact pad levels caused by such things as board warp. Since
eack yoke is independent so that it can follow the contours of the
board while containing proper contact pressure. As much as 0.015
level difference between adjacent contact pads can be compensated
for. This feature further eliminates intermittent contact due to
mechanical vibration and shock since the yoke is captured by the
printed circuit board and must follow the motion of the board. As
each contact is actuated, the rotational motion of the contact yoke
causes a wiping action.
The printed circuit support member is made of a resilient material,
such as neoprene rubber, and provides for vibration and shock
insulation as well as holding the board in a relatively fixed
position. The location of the support member is not critical and
the number and positioning of these members may vary according to
size and weight considerations.
It is to be understood that the present connector may be subjected
to many changes and modifications without departing from the spirit
or essential characteristics of the present invention. The present
embodiments are therefore to be considered in all respects as
illustrative and not restrictive.
* * * * *