Low insertion force connector using non-noble metal contact plating

An electrical connector permits the use of non-noble metals by providing mechanical advantage in obtaining high contact force with low insertion force. A pin is utilized as a cantilever beam to provide high contact force. A carrier, which is activated by insertion by a printed circuit board or the like, includes a lever forming part of the electrical connection. The lever is displaced causing deflection of the pin. The lever has contact points capable of piercing non-metallic oxides, thereby forming good electrical contacts.

BACKGROUND OF THE INVENTION 
This invention relates to an electrical connector and more particularly to 
a low insertion force connector having a contact arrangement which 
provides a good electrical contact and permits the use of non-noble 
metals. 
In many systems and for a variety of reasons, many electronic elements, 
components, circuitry, and interconnections are presently mounted, 
deposited, printed, or otherwise formed on one or both sides of a board (a 
printed circuit board, PCB) or other suitable substrate. Electrical 
interconnections of the PCB or the like and a backpanel or the like of the 
system is generally accomplished by a connector. 
These connectors generally include a housing which is bolted or otherwise 
affixed to the backpanel, and the housing is formed with a longitudinal 
slot for receiving one edge of the printed circuit board or the like. The 
connector is provided with a plurality of individual interconnection 
elements each of which is adapted to suitably contact the backpanel on one 
end, and to suitably contact the printed circuit board or the like on the 
other end. The electrical connections provided by these interconnection 
elements are formed in various well known manners with the connections to 
the backpanel being relatively permanent in comparison to the connections 
made with the printed circuit board or the like. 
In many connector configurations, the interconnection elements are formed 
so that one end of each interconnection element protrudes through the 
backpanel and wire-wrapped or otherwise connected. Connections between the 
interconnection element and the PCB or the like are generally made by 
mechanically biasing the interconnection elements of the connector into 
engagement with the edge contacts of the printed circuit board or the 
like. This mechanical biasing force serves two purposes, the first being 
to provide the electrical connections and the second being to grip the 
printed circuit board or the like, and thus hold the PCB or the like in 
the connector. It should be apparent that the biasing force exerted by the 
interconnecting elements must be relatively high to insure that good 
conductive contacts are made and maintained. The high biasing force causes 
a high insertion force of the PCB or the like which becomes excessive when 
the number of the interconnection elements of the connector is of a large 
quantity, the problem of the high insertion force being the impetus behind 
the development of zero insertion force and low insertion force 
connectors. 
Another problem with these connectors is that the contact areas of the edge 
contacts and the interconnecting elements will rub against each other with 
considerable force during insertion and removal of the printed circuit 
board or the like. Since the edge contacts of a typical printed circuit 
board are only a few thousandths of an inch thick, this rubbing action 
which occurs during insertion and removal of the printed circuit board 
tends to wear away the edge contacts and may well ruin a PCB after several 
insertions and removals. This rubbing action may also wear away highcost 
precious metal on the surface of the interconnecting elements which 
invites poor electrical contacts or corrosion and can result in hard to 
detect failures of the equipment. 
In view of these above stated problems several attempts have been made to 
produce what has become known in the art as a zero or low insertion force 
connector. Generally, these zero or low insertion force connectors are 
provided with mechanical actuating mechanisms which move the contact area 
of the interconnections elements out of the insertion and removal path of 
the printed circuit board or the like and allow the interconnecting 
elements to move into engagement with the edge contacts after the printed 
circuit board or the like has been inserted. Such a zero or low insertion 
force connector is disclosed in U.S. Pat. No. 4,189,199, entitled 
"Electrical Socket Connector Construction." This reference discloses an 
actuating mechanism which is activated by the insertion of an integrated 
circuit pack causing the interconnecting elements to move and make contact 
with the pins of the integrated circuit pack, resulting in a zero 
insertion force connector and eliminating any rubbing or wiping action 
between the pins of the integrated circuit pack and the interconnecting 
elements. Eliminating the rubbing or wiping action requires the 
interconnecting elements to be reasonably free from any contamination in 
order to form a good electrical contact. Gold or gold plated 
interconnecting elements and pins are presently being utilized in order to 
obtain contamination-free connections. With the cost of gold increasing 
substantially, the use of gold in connectors is becoming less desirable. 
Therefore, a need exists for a new and improved zero or low insertion force 
connector which allows the use of a non-noble metal by providing a way of 
wiping off or piercing the non-noble metallic oxides, thus forming good 
electrical contacts. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a new low insertion force 
connector has been devised. The electrical connector, for connecting to an 
edge contact of a printed circuit board or the like, includes a pin made 
of an electrically conductive resilient material and a carrier, made of an 
electrically insulative material which is actuated by insertion of the 
printed circuit board or the like. A lever, made of an electrically 
conductive material and being partially encased within the carrier, has 
two ends which are pointed or edged. The carrier is positioned within the 
electrical connector such that the first end of the lever makes a first 
contact point with the edge contact when the carrier is actuated by an 
insertion of the printed circuit board or the like. The carrier continues 
a rotation motion as the printed circuit board or the like is further 
inserted, and the second end of the lever makes a second contact point 
with the pin. The second end of the lever causes the pin to be deflected 
as a result of the rotation motion of the carrier. The deflection causes a 
force to be transmitted through the first and second contact points, 
thereby to permit a piercing action to occur at the first and second 
contact points. 
A specific embodiment of the electrical connector includes an electrically 
insulative housing which has two sidewalls, a front wall, a back wall, a 
top wall, and a base whose base centerline is along a surface of the base 
and parallel to the front and back walls, the surface of the base forming 
an inside surface of the electrically insulative housing. The top wall has 
an aperture centered in the top wall for receiving a printed circuit board 
or the like having a plurality of terminal strips. The electrically 
insulative housing has a cavity formed by the two sidewalls, the front 
wall, the back wall, the top wall and the base. A plurality of 
electrically conductive pins are arranged in two rows and are sufficiently 
flexible for providing a cantilever action. The two rows are along the 
base, parallel to and on opposite, equidistant sides of the base 
centerline. Each of the plurality of electrically conductive pins are 
affixed in and perpendicular to the base, spaced equally apart within the 
row, and extend through the base a sufficient length to permit external 
connections to be made to the plurality of electrically conductive pins. 
The pins further extend into the cavity a sufficient length to maintain an 
operative connection to the corresponding terminal strip of the printed 
circuit board or the like when the printed circuit board or the like is 
fully inserted into the electrical connector. Connecting carriers, are 
each positioned within the cavity for completing the operative connection 
between each of the plurality of electrically conductive pins to a 
corresponding one of the terminal strips of the printed circuit board or 
the like. The insertion of the printed circuit board or the like causes 
the connecting carriers to rotate thereby causing the connecting carriers 
to complete the operative connection. 
From the foregoing it can be seen that it is a primary object of the 
present invention to provide an electrical connector having a low 
insertion force. 
It is another object of the present invention to provide a low insertion 
force electrical connector using non-noble metals while providing good 
electrical contacts. 
These and other objects of the present invention will become more apparent 
when taken in conjunction with the following description, and attached 
drawings, wherein like characters indicate like parts and which drawings 
form a part of the present application.

DETAILED DESCRIPTION 
The construction of the preferred embodiment connector 1 of the present 
invention is shown in FIGS. 1 and 2. FIG. 1 is a partial exploded section 
view of the total connector assembly and FIG. 2 is an end-view 
cross-section of the connector 1 without the printed circuit board or the 
like inserted. Referring to FIGS. 1 and 2, the connector housing, 
comprising a top wall 10, a front wall 11, a back wall 12, two side walls 
13 (one is shown in FIG. 1) having a groove 33 for guiding the insertion 
of a printed circuit board, and a base 14, is shown which is made of an 
electrically insulative material. The walls and base of the connector 
housing form a hollow or cavity 17 within the connector 1. Top wall 10 has 
an opening 15 for permitting the insertion of a printed circuit board 
(PCB) 16 or the like into the connector 1, the PCB 16 having edge contacts 
or terminal strips 26. 
In the preferred embodiment, two rows of pins 18 are permanently fixed in 
the base 14 which extends a length outside the connector housing 19 
through the base 14 and into the cavity 17. The two rows are on opposite 
sides of a base centerline 20 and equidistant therefrom, the base 
centerline 20 being on the base surface and parallel to the front wall 11 
and the back wall 12. The pins 18 are spaced apart equally within the row. 
It will be recognized by those skilled in the art that many alternative 
configurations may be devised within the true scope of the invention, 
including, a single pin, a single row of pins, or a row or rows of pins 
not spaced apart equally. 
There is an electrically conductive lever 21 for each pin 18 providing the 
interconnection between the edge contact 26 and the pin 18, each lever 21 
being partially encased in a lever carrier 22, or simply referred to 
herein as a carrier 22, made of an electrically insulative material, with 
both ends of the lever 21 extending outside the carrier 22 and both ends 
having a sharp point or edge. Each pin 18 extends far enough into the 
cavity 17 such that the corresponding lever 21 always maintains pin 
contact. Two carriers 22 are positioned within cavity 17, such that the 
levers can rotate in a plane substantially perpendicular to the base 
centerline 20. The pin 18 is capable of being deflected as a cantilever 
beam when a force is applied, the cantilever beam action to be described 
hereinunder. In the ready state, i.e. a condition in which the connector 
is ready for the PCB 16 or the like insertion, the two carriers 22 are 
held in position by the force exerted by the pins 18. The pins 18 in the 
ready state are slightly deflected causing the two carrier surfaces 24 to 
press against one another, thereby holding carriers 22 in equilibrium 
between the pins 18. The sharp edges of the levers 21 hold the levers 21 
at a fixed point on the pins 18. As shown in FIG. 2A, a notch 25 can be 
placed in pin 18 to insure the lever 21/pin 18 position is maintained, the 
notch 25 being configured so as not to interfere with lever 21 rotation. 
The other end of the lever 21 is just outside opening 15 and may be in 
contact with the inside surface of top wall 10. The carrier 22 is so 
shaped that it doesn't interfere with the lever 21/pin 18 contact during 
any lever 21 rotation, the rotation of the lever 21 will be described in 
detail hereinunder. The carrier 22 is further shaped such that a portion 
of the carrier 22 extends in the path taken by the PCB 16 during 
insertion. The levers 21, pins 18, and edge contacts 26 may be made of an 
electrically conductive noble or non-noble metal. Again it will be 
recognized by those skilled in the art that, although the preferred 
embodiment shows the ends of the lever 21 having a chisel-like end 
configuration, the ends of the lever 21 may be configured to many 
different shapes while providing a good contact point with the pin 18 and 
the edge contact 26 respectively, the shapes including pointed, square 
edged, conical, and the like. 
FIG. 2 shows the connector 1 in the ready state. The levers 21 are in the 
position as mentioned above such that the PCB 16 can travel beyond the 
edges of levers 21 to the point depicted by PCB 16' where initial contact 
is made with carriers 22, the carriers 22 being shaped such that a portion 
extends in the path of travel of PCB 16 as mentioned above. 
FIG. 3 shows the connector 1 in which the PCB 16 has traveled a sufficient 
distance to cause rotation of the carriers 22 such that the edges of the 
levers 21, which were shown initially resting upon the inner surface of 
top wall 10, are presently making contact at contact points 45 with their 
corresponding edge contacts 26 (or terminal strips) of PCB 16. Such 
rotation also causes a force against pins 18 by lever 21, thereby 
initiating a deflection of pins 18 from the initial or ready state. As PCB 
16 is further inserted into connector 1, the leading edge of PCB 16 
continues to push against carriers 22, and together with the contact point 
45 made between levers 21 and edge contacts 26, the carriers 22 are 
rotated further, the initial contact points 45 being maintained throughout 
insertion of PCB 16 by the knife-like action of the sharp edges of levers 
21. 
FIGS. 4 and 5 show interim positions of PCB travel during insertion and 
FIG. 6 shows the PCB 16 fully inserted, the PCB 16 travel being stopped by 
a block 27. It will be recognized by those skilled in the art that 
alternative means may be included for stopping the PCB 16 travel, 
including a step 34 in groove 33 (reference FIG. 1). FIG. 5 shows the 
levers 21 having rotated perpendicular to the PCB 16 causing the maximum 
deflection of pins 18. From a lever position beyond the perpendicular, 
there exists a small component of force along the PCB 16 travel path which 
results in a latching action of the PCB 16. The force required for 
insertion is that force required to overcome the small force component 
along the PCB travel path. It can be seen that the sharp points or edges 
at each end of the levers along with a high contact force caused by pin 18 
deflection permits an action which pierces non-noble metallic oxides thus 
allowing good electrical connections. It will be understood by those 
skilled in the art that the piercing action of the non-noble metallic 
oxides includes actions such as friction, rubbing, knifing, cutting, etc., 
achieved by the lever 21 ends having alternative configurations mentioned 
above. 
FIGS. 7A and 7B are a cross-sectional view of a partial connector 1 taken 
along section line I--I of FIG. 5. FIG. 7A shows levers 21A through 21D 
mounted in carrier 22 and by some error, shows lever 21A extending farther 
out of carrier 22 than levers 21B, 21C, and 21D on the side making contact 
with PCB 16. In such case, lever 21A has created a high-spot thereby 
preventing levers 21B, 21C, and 21D from making any contact with their 
corresponding edge contacts 26. Pins 18A through 18D press against their 
respective levers 21A through 21D, pin 18A being the only pin benefitting 
from the cantilever action. In an alternative embodiment, in order to 
correct for the error or to compensate for manufacturing tolerances, the 
levers 21 can be loosely fitted into the carrier 22, permitting the lever 
21 to travel along its length, as indicated by the arrows of FIG. 7B, 
within the carrier 22. In this manner the lever 21 is responsive to the 
cantilever action of its respective pin 18 nullifying the effect of the 
high-spot. 
In yet another embodiment, each lever 21 is mounted in its own individual 
carrier 41, as shown in FIG. 8. In this embodiment, the lever 21 may be 
affixed within carrier 41 since the levers 21 will not be subject to a 
high-spot, each lever 21 being free to rotate independent of the other. 
FIGS. 9 and 10 show an alternative embodiment which includes fins 52 which 
is part of the carrier 22, the fins 52 being formed on the carrier 22 
along the carrier length for every few pins. The fins 52 are configured 
complementary to each other such that the carriers 22 may close as shown 
in FIG. 2, and such that the carriers 22 may be fully opened as shown in 
FIG. 6 without interfering with pins 18. A slot 51 is made in block 27 to 
permit the carriers 22 to open unimpeded, the slot 51 placement 
corresponding to the placement of the fins 52. The fins 52 are utilized to 
assist in holding the alignment of the carriers 22 such that the axis of 
rotation of the carriers 22 remains parallel to the base centerline. 
While there has been shown what is considered to be the preferred 
embodiment of the invention, it will be manifest that many changes and 
modifications can be made therein without departing from the essential 
spirit and scope of the invention. It is intended, therefore, in the 
annexed claims, to cover all such changes and modifications which fall 
within the true scope of the invention.