[0001] This invention relates to electrical connectors for high-density electrical circuits
and more particularly to an elastomeric contact pressure device for establishing electrical
connections between circuits on adjacent printed circuit cards or printed circuit
boards.
[0002] Nowadays, highly integrated semiconductor modules are mounted on cards which may
be plugged into circuit boards. High-density connector leads are provided for coupling
the modules to other devices on the same or on other boards. Separate entities of
high computing and memory capacity are created by interconnecting cards or boards,
each comprising at least one semiconductor module. Such interconnection of adjacent
cards or circuit boards, comprising highly integrated semiconductor modules and associated
dense connector leads, is even more critical than off-card connections where card
circuitry can be connected to input/output cabling on a rigid frame.
[0003] Generally speaking, the requirements for card-to-card or board-to-board connectors,
connecting semiconductor circuitries in adjacent modules, are the following:
a) the distance covered by the contact should be as short as possible;
b) positive mechanical retention of contact elements should be provided;
c) the connector elements should be held in position under positive spring action;
and
d) high rigidity and stiffness of the clamping member should provide for equal and
uniform spring action.
[0004] US-A-4,057,311 discloses an electrical board-to-board connector for coupling semiconductor
module circuits on two spaced-apart cards. According to the teaching of this reference,
two boards to be connected are mounted in different planes with edges overlapping.
The connector body has multiple parallel connection elements sandwiched between the
overlapping edges of the two adjacent boards. This approach requires connector leads
to be placed on oppositely directed surfaces of the boards.
[0005] US-A-3,597,660 discloses an off-card connector for coupling high-density edge conductors
on module circuit boards with input/output circuit conductors of a cabling network.
The overlays are formed on a flexible thin layer of polyimide material by printed
circuit techniques and contact pressure is achieved through a resilient body under
a pressure applying mechanism.
[0006] A major problem associated with connecting electrical-circuits on separate circuit
boards and providing an electrical connection therebetween, especially during the
assembly process, is the potential for attracting dust or other contaminants to the
connectors. It is important that the electrical connection be of high quality, due
to the relatively small dimensions of the electrical lines. The integrity of the electrical
connections is a function of the amount of extraneous material that adheres to the
conductive elements. Accordingly, the copper surfaces to be connected should be as
clean as possible prior to an< during the assembly process.
[0007] It would be advantageous to provide a system for electrically and structurally connecting
circuits on separate printed circuit boards.
[0008] It would further be advantageous for this system of circuit connections to be simply
constructed with a minimum of moving parts and assembly complexity.
[0009] Moreover, it would be advantageous to provide a system for electrically connecting
circuits on separate boards while ensuring the highest degree of cleanliness prior
to and during the final assembly.
[0010] It would also be advantageous to provide an electrical bond between separate circuits
on respective circuit boards having a means for positive mechanical retention so that
the possibility of eventual disconnection is minimized or eliminated.
[0011] It would further be advantageous to provide a system for connecting a plurality of
separate conductors on abutting circuit boards such that positive retention is assured
equally for all of the connected conductors.
[0012] It would also be advantageous to provide preformed elements that are deformable under
pressure to provide wiping and cleaning action of the copper surfaces immediately
prior to completing the electrical connections.
[0013] It is the object of the invention to provide an improved connector between semiconductor
module cards or boards. The connector should establish connections along the shortest
possible distance, both in the wiring and in the connector itself. The connector should
further provide positive mechanical retention and positive spring action. For uniform
spring action at multiple connector contacts, high rigidity and stiffness are required.
[0014] Moreover, it is an object of the present invention to provide a system for cleaning
the contacts between electrical conductors immediately prior to and during the making
of electrical connections therebetween.
[0015] A further object of the invention is to provide for a multiple card-to-card connector
having. a wiping action. More particularly it is a further object of the invention
to provide for a truss displacement of the connector elements across the lands to
be connected when applying a force upon mounting the connector body.
[0016] According to the present invention, multiple preformed connector elements are shaped
to a radius, truss or similar form between the lands to be connected. When the resilient
layer carrying the connector elements has a force applied thereto by a fastening or
clamping means, truss displacement of the connector elements across the lands takes
place, thus assuring a reliable contact under all circumstances. A layer of relatively
high durometer material is attached to the other surface of the resilient layer to
provide stiffness.
[0017] In accordance with the principles of the present invention there is provided a high
density electrical connector for multiple connection of closely spaced juxtapositioned
lands on a first circuit board to corresponding lands on a second circuit board abutting
said first circuit board. The connector is characterized by a connector body having
a first layer of relatively high stiffness, a second relatively resilient layer and
a plurality of preformed connecting elements, said connector body being adapted to
be mounted on one surface of said first and second circuit boards for establishing
spring-loaded multiple connections so that each one of said preformed connecting elements
wipes across associated lands to be connected on said first and second circuit boards.
[0018] The foregoing and other objects, features and advantages of the invention will be
apparent from the following more particular description. of a preferred embodiments
of the invention, as illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019]
FIGURE 1 is a schematic cross-sectional view of part of two abutting circuit boards
and a multiple connector in accordance with the present invention across the edges
thereof;
FIGURE 2 is a side view of the multiple connector taken along line 2-2 of FIGURE 1;
FIGURE 3 is a perspective view of the multiple connector body according to the present
invention;
FIGURE 4 is an exploded cross-sectional side view of the multiple connector and circuit
board according to the present invention;
FIGURE 5 is a cross-sectional end view of the multiple connector, drawing to relative
scale and taken along line 5-5 of FIGURE 4; and
FIGURE 6 is an exploded cross-sectional view of the multiple connector with a copper
line positioned therein.
FIGURE 7 is a cross-sectional view of the preferred embodiment of the multiple connector
shown in its initial position;
FIGURE 8 is a cross-sectional view of the device shown in FIGURE 7 in its final position;
FIGURE 9 is an exploded cut-away view of the connector element impregnated in polyimide;
FIGURE 10 is a cross-sectional view of an alternate embodiment of the multiple connector;
Figure 11 is an isometric view of the connector body of FIGURE 10;
FIGURE 12 is a free body representation of the connector of FIGURES 10 and 11; and
FIGURES 13, 14 and 15 are cross-sectional views of another alternate embodiment of
the multiple connector according to the present invention, shown in initial, intermediate
and final positions, respectively.
[0020] Referring now to FIGURE 1, there is shown a first printed circuit board 10 on which
is mounted one or more semiconductor modules and associated connecting circuits, not
shown. The board 10 abuts a second printed circuit board 20 along common edges 25.
[0021] Disposed on printed circuit board 10 is a land 30, which terminates circuitry and
is used to connect the semiconductor modules to outside devices. Circuit cards or
boards carrying a highly integrated semiconductor module can have at least twenty
lands per centimeter which are to be connected to corresponding lands on an abutting
card or board. In spite of careful, automated manufacturing of the cards and attached
lands to close tolerances, dimensional differences do occur and are compensated for
by spring biasing as hereinbelow described. Corresponding to land 30 on printed circuit
board 10 is another land 40 disposed on printed circuit board 20.
[0022] Extruded copper 50 is placed directly above the lands 30 and 40 and forms an electrical
conductor therebetween. It should be understood, however, that any electrically conductive
material, such as platinum, aluminum and the like, can be used in place of copper
50. When oxidizable material such as copper is used, a plating process should be performed
before connections are made. Gold or phosphor bronze plating of the copper lines 50
is preferred.
[0023] Surrounding the copper conductor 50 is a relatively resilient material 70 such as
low durometer rubber. Any suitable polymer, such as polyvinyl chloride, thermoplastic
elastomer (TPE) or the like with a durometer range of 60A-50D, can be used for this
function. The resilient material acts as a spring to urge the cooper conductor 50
against the lands 30 and 40.
[0024] Bonded to the resilient material 70 is a more stiff, relatively high durometer rubber
80. Any high durometer material, such as styrene, acrylonitrilebutadiene-styrene (ABS),
polypropylene or the like with a durometer range greater than 50D, may be used as
the relatively stiff material 80, whose function it is to distribute a force transversely
along the length of the common edges 25 of the boards 10 and 20.
[0025] Referring now also to FIGURE 2, there is shown a cross-sectional view taken along
line 2-2 of FIGURE 1. It can be seen that a plurality of lands 30 can be interconnected
with corresponding adjacent lands, not shown in FIGURE 2, and can be held in position
by positive clamping action as hereinbelow further described. The multiple connector
elements 50 formed of copper conductors are all spring loaded due to their relationship
to the resilient material 70 in which they are embedded. The multiple connections
between the multiple connector elements 50 and the lands 30 and 40 (FIGURE 1) on cards
10 and 20 are made under positive spring pressure. When the relatively rigid, stiff
member 80 bears down on the more resilient material 70, a substantially uniform pressure
is urged against each individual connector element 50.
[0026] Referring now also to FIGURE 3, there is shown the connector body, shown generally
as reference numeral 210, made of dual durometer rubber. The resilient portion 70,
for providing spring action, is in the upper position in FIGURE 3. Bonded to the resilient
material 70 is a more stiff material 80 to provide rigidity. As the connector body
210 is extruded from a suitable extruder, not shown, copper wires 50 are embedded
in the resilient material portion 70 thereof. In FIGURE 3, a horizontal arrow indicates
the direction in which the connector body 210 and copper lines 50 are extruded.
[0027] The extrusion process can be performed by any suitable means well known in the art.
By adding to this extrusion process coils of plated copper wire which are fed into
the extrusion die, the wires 50 are bounded with the elastomer 70, thus providing
the actual multiple connectors.
[0028] In the course of extrusion, the relatively low durometer material 70 is bonded to
the high durometer material 80 by heat in the preferred embodiment. It should be understood
that any suitable means of bonding is acceptable and, in fact, the connection between
the low durometer and the high durometer material need not even be permanent. The
extruded part 210 can be produced in various lengths and cut to the required engagement
length. Clearance holes, not shown, are drilled or stamped in the connector body for
mounting to an understructure.
[0029] Referring now also to FIGURE 4, adjustable bolts or screws 160 and 170 are screwed
into corresponding nuts 190 and 200 to mount and clamp the connector body 210, previously
cut to length, to the printed circuit board 10. The copper wire conductors 50 are
thereby clamped between the conductor body 210 and the printed circuit board 10. It
should be understood that while nuts and bolts are shown in FIGURES 2 and 4 as the
means for clamping the resilient rubber layer 70 to the printed circuit board 10,
thereby sandwiching the copper wires 50 and lands 30, any suitable positive clamping
means can be employed, such as snap latches and the like.
[0030] By applying a specified torque to nuts 190 and 200, the high durometer layer 80 is
made to bear down upon low durometer layer 70, thus forcing the copper wires 50 against
the lands 30 and 40 (FIGURE 1) of the abutting cards or boards 10 and 20 with uniform
pressure applied at each individual connection.
[0031] Thus the semiconductor module circuitry on card or board 10 is connected to the semiconductor
module circuitry on card 20 through the connector device shown in detail in FIGURE
4, providing multiple connections between the lands 30 on card 10 and corresponding
lands 40 on card 20.
[0032] The high durometer layer 80 provides the required stiffness, while the low durometer
layer 70 provides specified spring action and equal torque at each individual copper
connector element 50.
[0033] Referring now also to FIGURE 5, there is shown a cross-sectional view of the clamping
device. One bolt 160 and corresponding nut 190 are used to clamp the connector body
210 (resilient material 70 facing down) to appropriately aligned and abutting printed
circuit boards 10 and 20. The copper line 50 is sandwiched between the connector body
210 and the printed circuit boards 10 and 20 and forms an electrical connection between
the lands 30 and 40 on the edges of the boards 10 and 20.
[0034] Referring now also to FIGURE 6, there is shown an exploded cross-sectional view of
one of the copper lines 50 embedded in the low durometer material 70 which, in turn,
is bonded to the more rigid high durometer material 80.
[0035] A void 230 is originally manufactured in the low durometer material 70 for receiving
the copper line or wire 50. The copper wire 50 is placed in the low durometer material
70 so that the center or origin 270A of the wire 50 lies substantially in the plane
defined by the upper level of the low durometer material 70.
[0036] The copper wire 50 has a cross-section which is generally circular but includes a
triangular protrusion 240 culminating in an apex 245. The apex 245 of the protrusion
240 is affixed to a bond line 248 formed between the resilient rubber layer 70 and
the hard rubber layer 80, substantially parallel to the outer surfaces thereof. The
copper 50 is thus affixed to both the resilient material 70 and the hard material
80 at the apex 245.
[0037] The straight sides of the triangularly shaped protrusion 240 formed in the copper
wire 50 are identified by reference numerals 250 and 260 respectively. Along these
sides 250 and 260 of the copper wire 50 is bonded the resilient rubber 70. An angle
6 is formed between the bond line 248 and an imaginary line 249A that bisects the
protuberance 240, passing through the origin 270A. The size of the angle 6 is significant
in regard to the wiping action as hereinbelow described.
[0038] The initial position of the copper line 50 relative to circuit board 10 is such that
the copper line 50 touches the land 30. at a point identified by reference numeral
272.
[0039] When a constant vertical force is applied from the lower surface 274 of the relatively
rigid rubber material 80, as indicated by a vertical arrow in FIGURE 6, the copper
wire 50 is pressed into the resilient rubber 70, filling the void 230 and decreasing
angle 6 linearly and proportionally. Point 245 forms a pivot around which the copper
wire 50 is forced to rotate clockwise during the interconnection process. In the process
of forcing the copper 50 into the resilient material 70, some of the resilient material
290 is displaced.
[0040] Dimension X is the displacement area of the lands 30 and 40, perpendicular to the
common edges 25 (FIGURE 1). As the copper 50 is pressed into the resilient material
70, the upper portion of the copper 50 is caused to rub against the lower surface
of both cards 10 and 20 (FIGURE 1) in a wiping action. The copper line 50 shifts position
relative to the connector body 210. The final location of the copper line 50 is identified
by phantom lines in FIGURE 6. Also shown in phantom is the final position of the imaginary
line 249B that bisects the triangular protuberance 240, forming one side of the apex
245 thereof and defining a final angle Φ. Angle Φ is related to dimension X such that
as 6 decreases to B, the wiped surface measured by X increases as the cosine of the
angle. The area denoted as X, bounded by the initial contact position 272 between
the copper wire 50 and land 30 and the final contact position 276, is cleaned of dust
particles, contaminants, oxidation and the like during the interconnection process.
Thus, the electrical resistance between the copper wire 50 and the two lands 30 and
40 of printed circuit boards 10 and 20 is greatly reduced due to wiping action. Thus,
there is more predictability in the electrical performance of the overall system.
[0041] As the copper wire 50 is interconnected under pressure, the origin 270A of the copper
wire 50 is displaced to its final position identified by reference numeral 270B. The
copper line 50 and lands 30 are compressed and forced into contact along the major
portion of area X.
[0042] Referring now also to FIGURE 7, there is shown a schematic illustration of another
embodiment of a connector body, shown generally as reference numeral 211, made of
dual durometer rubber. The connector body 211 is shown in its initial position. A
resilient portion or layer 71 provides spring action. Bonded to the resilient material
71 is a layer of more stiff material 81 to provide rigidity. The stiff material 81
has a protuberance 85 that is positioned in a corresponding upper surface depression
formed in the resilient layer 71.
[0043] A layer 90 of polyimide or other suitable material is bonded to the lower surface
of the resilient layer 71. The layer 90 has embedded therein electrically connecting
elements, not shown in FIGURE 7. The resilient layer 71 also has a lower surface depression
92 across its width over the common edges 25 between the abutting boards 10 and 20.
Since the opposite surface of the resilient layer 71 facing the layer of high stiffness
81 contains a similar transverse depression 85, the resilient layer 71 is thinner
between the lands to be connected.
[0044] Referring now also to FIGURE 8, the connector body 211 is shown in its final, compressed
position. When a downward force is applied when mounting the connector, the lower
depression 92 in the low durometer layer 71 is flattened by the protuberance 85 in
the high durometer layer 81, pressing down the printed circuit connectors on layer
90 against the lands 30 and 40 (FIGURE 1) on the abutting cards 10 and 20, performing
a wiping action.
[0045] Referring now also to FIGURE 9, there is shown an exploded view of the polyimide
layer 90 with spaced apart substantially parallel copper lines 50 embedded therein.
The resilient layer 71 and stiff layer 81 are shown partially covering the layer 90.
[0046] In FIGURE 9, a vertical arrow indicates the direction in which the connector body
211 and layer 90 with circuitry 50 are extruded. The extrusion process can be performed
by any suitable means well known in the art. The extrusion die has a corresponding
inverted V
-shaped form. After this extrusion process is complete, circuitry on layer 90 is bonded
to the connector body 211 to form the connector.
[0047] In the course of extrusion, the relatively leu durometer material 71 is bonded to
the high durometer material 81 by heat in the preferred embodiment. It should be understood
that any suitable means of bonding is acceptable and, in fact, the connection between
the low durometer and the high durometer material need not even be permanent. The
extruded part 211 can be produced in various lengths and cut to the required engagement
length. Clearance holes, not shown, are drilled or stamped in the connector body for
mounting to an understructure.
[0048] Referring now also to FIGURE 10, there is shown an alternate embodiment of a card-to-card
connector according to the invention. The card 10 is provided with a number of circuit
termination lands 30 which are connected to lands 40 on abutting card 20 through the
multiple connector body 212. The connector body 212 consists of a first relatively
high durometer rubber layer 82 and a second relatively low durometer rubber layer
72 having an inverted approximate V-shape configuration. The connector layers 82 and
72 are mounted on the edge surfaces of abutting cards 10 and 20 by a screw 161 and
nut 191. The adjustable bolt or screw 161 is screwed into corresponding nut 191 to
mount and clamp the connector body 212, previously cut to length, to the printed circuit
boards 10 and 20. The copper lines 50 (not shown in FIGURE 10) are thereby clamped
between the connector body 212 and the printed circuit boards 10 and 20. It should
be understood that while a nut and screw are shown in FIGURE 10 as the means for clamping
the resilient rubber layer 72 to the printed circuit boards 10 and 20, thereby sandwiching
the copper lines 50 and lands 30 and 40, any suitable positive clamping means can
be employed, such as snap latches and the like. By applying a predetermined torque
to screw 161, a truss displacement action results. Under pressure a wiping action
takes place between the connecting element 212 and the corresponding lands 30 and
40 on the abutting cards 10 and 20. The copper connector leads 50 are forced against
the lands 30 and 40 of the abutting cards or boards 10 and 20 with uniform pressure
applied at each individual connection.
[0049] Thus the semiconductor module circuitry on card or board 10 is connected to the semiconductor
module circuitry on card 20 through the connector device shown in detail in FIGURE
9, providing multiple connections between the lands 30 on card 10 and corresponding
lands 40 on card 20.
[0050] The high durometer layer 82 provides the required stiffness, while the low durometer
layer 72 provides specified spring action and equal torque at each individual copper
connector element 50.
[0051] Referring now also to FIGURE 11, there is shown an exploded isometric view of the
connector body 212 consisting of a three-layer V-shaped sandwich: high durometer layer
82 connected to low durometer layer 72 connected to layer 90, the layer 90 having
electrically conductive elements (FIGURE 9) embedded therein.
[0052] The distance D from the apex 94 to layer 90 is approximately 6...18 mm in the preferred
embodiment.
[0053] The arrow in FIGURE 11 indicates the direction that the preformed connector body
211 is extruded during manufacture, corresponding to the direction shown in FIGURE
9.
[0054] FIGURE 12 illustrates a free body diagram of the connector 212 and the fastener comprising
screw 161 and nut 191 (FIGURE 10) subjected to a specific force F. Lines BA and BC
correspond to the legs of the inverted V-shaped connector body. Letter h indicates
the height of the connector. Variable X
1 represents one half the initial distance between the legs of the inverted V-shaped
connector body 212 at the surface of the boards or cards 10 and 20. Upon mounting,
the fastener 161, 191 provides force F, resulting in the following equilibrium force
analysis.
[0055] 
The sum of the moments about point M is:

[0056] From FIGURE 12 it is apparent that horizontal forces:

where 9 represents the angle between legs of the connector body 212 in their final,
compressed positions. As a result of applying force F to the connector body, displacement
occurs and a wiping action Z takes place, according to this equation:

where t represents the angle between legs of the connector body 212 in their initial
positions and X
2 represents one half the final distance between the legs of the inverted V-shaped
connector body at the surface of the boards or cards.
[0057] This wiping action with force F applied through the resilient layer 72 to the individual
connector elements 50 assures a reliable contact at each individual land 30 and 40
by means of the resulting positive spring action.
[0058] In FIGURES 13-15, another alternate embodiment of the card-to-card connector is shown.
The high durometer rubber layer 83 for rigidity is provided with low durometer rubber
layers 73 and 74 for spring action. The connector body of an inverted V-shaped configuration
with legs 123 and 124 is supported by a central part 125. The legs 123 and 124 are
provided with high durometer rubber parts 126 and 127 for rigidity, provided with
a polyimid layer 95 or a layer of a similar material, carrying the printed connector
circuitry (FIGURE 9). The connector body is again fabricated by an extrusion process,
extrusion being carried out in a direction perpendicular to the plane of the drawing.
[0059] FIGURES 14 and 15 show different stages of the connector device when being mounted
with pressure applied to the high durometer rubber layer 83. FIGURE 14 shows an intermediate
stage, in which the lower parts of the legs 123 and 124 of the connector are wiped
across the lands 30 and 40 (FIGURE 1) on the upper surfaces of the abutting cards
10 and 20.
[0060] FIGURE 15 shows the final stage. With pressure applied to the stiff layer 83, both
legs 123 and 124 of the inverted V-shaped connector body are pressed bodily against
the lands 30 and 40 on the upper surfaces of the cards 10 and 20, resulting in a wiping
action. In this final stage, the resilient layers 73 and 74 contact the stiff layers
126 and 127, respectively, thus providing a positive spring action at each individual
contact between each printed circuit connector element and associated lands on the
abutting cards, which spring action is applied after the wiping action has taken place.
[0061] From the foregoing description, it can be seen that connecting two separate lands
on two separate printed circuit boards or cards-respectively has been shown. This
manner of connecting provides the shortest possible distance between the contact lands.
Moreover, the manufacture of this connector is relatively inexpensive and space requirements
are low.
[0062] While the preferred and alternate embodiments of the invention have been illustrated
and described, it is to be understood that there is no intention to limit the invention
to the precise constructions herein disclosed and the right is reserved to all changes
and modifications coming within the scope of the invention as defined in the appended
claims.
1. Electrical connector for multiple connection of closely spaced juxtapositioned
lands on a first circuit board to corresponding lands on a second circuit board abutting
said first circuit board, characterized by a connector body (210...212) having a first
layer (80...83) of relatively high stiffness, a second relatively resilient layer
(70...73), and a plurality of preformed connecting elements .(50), said connector
body (210...212) being adapted to be mounted on one surface of said first and second
circuit boards (10, 20) for establishing spring-loaded multiple connections so that
each one of said preformed connecting elements (50) wipes across associated lands
(30, 40) to be connected on said first and second circuit boards (10, 20).
2. Connector in accordance with claim 1, characterized in that said plurality of connecting
elements (50) are embedded in one surface of said resilient layer (70...73).
3. Connector in accordance with claim 2, characterized in that said plurality of connecting
elements (50) are electrically conductive metal wires bonded to said resilient layer
(70...73).
4. Connector in accordance with claim 1, characterized in that said first layer (80...83)
of said connector body (210...212) is a polymer of relatively high hardness and that
said second layer (70...73) is a polymer having a hardness lower than that of said
first layer (80...83).
5. Connector in accordance with claim 1, characterized in that said resilient layer
(71) has a cavity (92) in a location opposite a protuberance (85) shaped on said stiff
layer (81) along at least part of the bond line (248) between said layers (71, 81),
and that said resilient layer (71) has a wire-carrying layer (90) attached to one
surface thereof, such that when said stiff layer (81) is forced against the lands
(30, 40) on said circuit boards (10, 20) said wires (50) are brought in contact with
both of said lands (30, 40) on the circuit boards (10, 20) to form an electrically
conductive connection therebetween.
6. Connector in accordance with claim 1, characterized in that said first and second
layer (82, 72) have an inverted V-shaped form, the resilient layer (72) having on
one surface a flexible layer (90) provided with printed circuit connecting elements
(50).
7. Connector in accordance with claim 1, characterized in that said resilient layer
(71) has a relatively thin portion formed by top and bottom transverse depressions
(85, 92), said connecting elements (50) extending across the bottom depression (92)
on a flexible layer (90).
8. Connector in accordance with claim 1, characterized in that said resilient layer
(72) has at least two segments and an inverted V-shaped elongated body provided with
connecting elements (50) on the undersurface of an additional flexible layer (90)
attached thereto.
9. Connector in accordance with claim 1, characterized in that said connecting elements
(50) form a gap with said circuit boards (10, 20) in an initial position, said gap
being substantially eliminated in a final position.
10. Connector in accordance with claim 9, characterized in that said electrical connecting
elements (50) are automatically wiped across said lands (30, 40) between their initial
and final positions.