Zero insertion force cable interface

A connector assembly includes a female dual row connector, and a male dual row connector configured to be inserted into the female dual row connector. The female connector is configured to be compression mounted onto a circuit card, and has conductive tails for being brought into contact with traces on the card or circuit board. The female connector may have a stiffener to help it maintain its shape. The rows of contacts of the male connector may be selectively brought together (collapsed) or moved apart (expanded). The rows of contacts are collapsed during insertion or removal of the male connector from the female connector, thus allowing zero force insertion of the male connector into the female connector. The collapsing and expanding of the rows for the male connector may be accomplished through any of a variety of mechanisms.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention relates to electrical connectors, and to methods for coupling together and de-coupling electrical connectors.

2. Description of the Related Art

In the field of silicon chip testing, probe cards with multiple probes attached have been used to contact specific, accurately-located probe points on the chip. Multiple transmission line cables have been used to communicate the probe-board positions with an attendant test computer. Typically, the interface between the test computer and the probe card has been a multiplicity of spring pins (commonly referred to as “pogo pins”) positioned to engage the probe board in compression, and coupled to the transmission lines to the cable. However, for some testing applications many pins, i.e., 1,000 pins or more, are required, making the forces normal to the probe board substantial. Deflection of the probe board caused by the total compressive force of the pogo pins will cause the probe pins to move and possibly lose their accurate positioning.

Many methods have been employed in the past to ameliorate this loss of accurate positioning of the probe pins. Examples of such methods are putting reinforcing strips on the board surface, using a vacuum support of the probe board, and reducing individual spring pin forces. None of these methods has been found to completely eliminate the deflection, but at best they merely control the deflection to an acceptable amplitude. From the foregoing it will be appreciated that there's room for improvement with regard to connections in the field of silicon chip testing, and more broadly in the general field of electrical connection.

SUMMARY OF THE INVENTION

According to an aspect of the invention, a male electrical connector includes: a platform; and contacts on at least one major surface of the platform. Thickness of the platform may be selectively changed.

According to another aspect of the invention, a female connector includes a connector body; and compression contacts attached to the connector body.

According to yet another aspect of the invention, a connector assembly includes: a male connector that in turn includes: a collapsible platform; and male contacts on major surfaces of the platform; and a female connector having female contacts for engaging the male contacts. The platform is configured to be collapsed for zero force insertion into the female connector, and is configured to be expanded to allow the male contacts to engage the female contacts.

According to still another aspect of the invention, a method of coupling together a male connector and a female connector, includes the steps of: compressing a platform of the male connector; inserting the platform between rows of female contacts of the female connector; and expanding the platform, thereby bringing male contacts on major surfaces of the platform into engagement with the female contacts.

According to another aspect of the invention, the male connector platform is connected to multiple transmission line cables and is the conduit through which the cables communicate with the probe board.

DETAILED DESCRIPTION

A connector assembly includes a female dual row connector, and a male dual row connector configured to be inserted into the female dual row connector. The female connector is configured to be compression mounted onto a circuit board, and has conductive tails for being brought into contact with traces on the card or circuit board. The female connector may have a stiffener to resist bowing in the connector caused by the reaction force of the compressive contact tails on the board. The rows of contacts of the male connector may be selectively brought together (collapsed) or moved apart (expanded). The rows of contacts are collapsed during insertion or removal of the male connector from the female connector, thus allowing zero force insertion of the male connector into the female connector. The collapsing and expanding of the rows for the male connector may be accomplished through any of a variety of mechanisms.

Referring toFIG. 1, a connector assembly10includes a female connector12that mates with a male connector14. The female connector12is configured to be mounted on a circuit board. The female connector12includes attach screws20and22for mechanically coupling the female connector12to the circuit board. The female connector12has a plurality of conductive tails24, arranged in rows26and28on either side of a bottom surface30of the female connector12. The conductive tails24are used for electrically coupling contacts in the female connector12to suitable traces on the circuit board to which the female connector12is mounted. The conductive tails24are brought into cantilever compression contact with the traces on the circuit board, as the attach screws20and22are used to mount the female connector12to the circuit board.

The female connector12has within its connector body34two rows of female contacts. The female connector12also has metal stiffeners38on either side to provide additional stiffness for the female connector12, as described in greater detail below. The female contacts of the female connector12mate with male contacts40of the male connector14. The male contacts40are arrayed on opposite sides of a substantially-planar platform44. The male connector14includes a pair of guide pins46and48. The guide pins46and48are inserted into corresponding sockets or recesses in the attach screws20and22of the female connector12. The guide pins46and48aid in properly positioning the male connector14relative to the female connector12as the male connector14is inserted into the female connector12.

As described in greater detail below, the platform may be selectively contracted (made thinner) and expanded (made thicker), by use of a mechanism within the male connector body60. Thus the rows62and64of the male contacts40may be selectively brought together during insertion of the male connector14into the female connector12. This allows coupling of the connectors12and14with essentially zero insertion force (ZIF). Once the male contacts40are inserted into the female connector12, the platform44may be expanded, moving the rows62and64of the male contacts40apart from one another, and into contact with the corresponding rows of contacts within the female connector12.

The mechanism for accomplishing the expansion and contraction of the platform44includes movement as a ramp arm68and a through arm70. The arms are coupled together at a link72. The link72between the through arm70and the ramp arm68may have some clearance, allowing some degree of clearance or “float” between the pawl73of the through arm70and the mating hole74of the ramp arm68. This clearance aids in proper mating of the connectors12and14.

The male connector14may be part of a cable assembly76. The cable assembly76includes one or more cables80that are inserted into the male connector body60. Within the male connector body60, the conductors of the cable(s)80are coupled to the rows62and64of the male contacts40. The cable80may be one or more cables of any of a variety of cable types, such as coaxial signal wire, twin axial signal wire, twisted pair, or single conductor wire.

Turning now toFIGS. 2A and 2B, further details are given of the female connector12and its coupling to a circuit board84. The female connector body34has a central recess88for receiving the platform44of the male connector14(FIG. 1). Female contacts90are in rows92and94on opposite sides of the central recess88. The female contacts90are configured to mate with the male contacts40of the male connector14(FIG. 1). The female contacts90include the conductive tails24at the bottom surface30of the female connector12. The conductor tails24are in contact with conductive traces98of the board84. Mechanically coupling the female connector12to the board84presses the conductive tails24down against the conductive traces98, causing some deflection in the conductive tails24that results in a compressive force of the conductive tails24against the conductive traces98.

The female connector body34also includes end recesses100and102for receiving the attach screws20and22. The attach screws20and22are inserted into the end recesses100and102, and engage blind threaded inserts104and106that are in the circuit board84. As the attach screws20and22engage the threaded inserts104and106and are tightened, the female connector12is pulled against the circuit board84. This causes a compression force on the contact tails24, resulting in engagement between the contact tails24and the conductive traces98on the circuit board84. The forces of compression on the contact tails24are equal to and opposite the attaching force holding the attach screws20and22to the inserts104and106. Thus the net force on the circuit board is essentially zero.

The female connector body34may be largely made of a suitable plastic. However, the body may have a pair of stiffeners38, one on either side of the female connector body34. The stiffeners38may aid in preventing bowing of the female connector12due to the contact forces from the engagement of the attach screws20and22, and the contact tails24, with the circuit board84. The stiffeners may be made of a suitable sheet metal, for example, a suitable stainless steel.

As noted above, the attach screws20and22have guide holes or sockets110and112for receiving the positioning or guide pins46and48of the male connector14(FIG. 1). It will be appreciated that other suitable alignment mechanisms or alignment mechanism locations may alternatively be utilized to facilitate proper alignment of the connectors12and14.

With reference now in addition toFIGS. 3A and 3B, details are discussed of the configuration of the female contacts90within the female connector12.FIG. 3Ashows the female contacts90molded into a header body113. The female contacts90, in the unloaded condition shown inFIG. 3A, have a small gap G1between them.

FIG. 3Bshows the female contacts90in their preloaded condition, resting on ledges114of a cap115, with a larger gap G2between bends116of the contacts90. The ledges114are insert molded into the cap115. The ledges114are located just outside of the gap G2, such that when the platform44of the male connector14(FIG.1) is inserted into the female connector14only a small amount of deflection is required to separate the female contacts90to allow insertion. Insertion causes the female contacts90to deflect slightly outward, away from a centerline of the female connector14. This causes the female contacts90to be moved away from and out of contact with the ledges114, transferring the preload forces of the female contacts90from the ledges114to the male contacts40(FIG. 1) of the male connector14.

Most of the deflection of the female contacts90required for insertion is done by preloading the female contacts90by bending them back, having them press inward against the ledges114. This preloading of the female contacts90may be substantially at the desired contact force for the female contacts90to press against the male contacts40(FIG. 1) when the connectors12and14are mated together. The preloading of the female contacts90allows the desired contact force to be achieved with only a minimal further deflection of the female contacts90required during mating of the connectors12and14.

Turning now toFIG. 4, details of the male connector14are discussed. The male connector body60includes a pair of plastic shells120and122that enclose the working parts of the male connector14. The shell120includes a shell keyed section124of alternating protrusions and recesses. The shell keyed section124mates with a corresponding header keyed section128of a male contact header130. Similar mating of keyed sections is provided between the shell122and a male contact header132. The mating keyed sections124and128maintain the position of the male contact headers130and132, relative to the shells120and122.

Besides the male contact headers130and132, which together make up the platform44, the shells120and122enclose parts of a shuttle (slider)136that is moved back and forth so as to selectively control the thickness of the platform44. The shuttle136is used to move selectively the male contact headers130and132closer to one another, or further away from one another. As discussed above, the male contact headers130and132are moved toward one another for insertion of the male connector14into the female connector12. The male contact headers130and132are then moved apart to allow the male contacts40to engage the corresponding female contacts90(FIG. 2A), thereby electrically coupling the female connector12and the male connector14. For disengagement of the male connector14from the female connector12, the male contact headers130and132are brought together once again, decreasing the thickness of the platform44, and disengaging the male contacts40from the female contacts90.

The positioning or guide pins46and48are attached to one or the other of the shells120and122. The guide pins46and48may be suitably placed within a mold as the shells120and/or122are molded around them. The guide pins46and48may each contain a boss or undercut which allows them to be retained in the shells as the shells120and122are fastened together. The shells120and122may be held together by suitable fasteners138.

With reference in addition toFIGS. 5 and 6, details and operation of the shuttle136are now described. The shuttle136includes a central spine140that runs between the male contact headers130and132. The spine140has spine ramps142on its major surfaces on both sides. The spine ramps142are used for engaging inner (inboard) ramped surfaces144and146of the male contact headers130and132, respectively. The spine ramps142are used to press outward against the inner ramped surfaces144and146of the male contact headers130and132, when the shuttle136is appropriately moved. The spine140may be made of a suitable sheet metal, with the spine ramps142being plastic protrusions formed on the major surfaces of the spine140.

The shuttle136also includes ramped members150and152, also referred to herein as covers. The ramped members150and152have respective ramped inner surfaces154and156for engaging header outer (outboard) ramped surfaces160and162of the male contact headers130and132. The inner ramped surfaces or return ramps154and156of the ramped members150and152, and the outer ramped surfaces160and162of the male contact headers130and132, are configured such that the ramped surfaces may cooperate with one another to press the male contact headers130and132toward one another, when the shuttle136is moved in the appropriate direction.

The spine140and the ramped members150and152are connected together by bearing blocks170and172on either side of the male connector body60. The bearing block170is also attached to the ramp arm68. The bearing blocks170and172are able to slide back and forth relative to the shells120and122. The shells120and122have suitable recesses for allowing movement of the shuttle136back and forth.

As described above, the ramp arm68is coupled to a through arm70via a link72. The through arm70is in turn coupled to an appropriate mechanism for moving it back and forth, thereby actuating movement of the shuttle136back and forth.

In its normal activated configuration (with no external force applied), the platform44is expanded, with the spine ramp142engaging the inner ramped surfaces144and146of the male contact headers130and132, to maintain the male contact headers130and132apart from one another. When contraction of the platform44is desired, for example, in order to insert the platform44into the female connector12, or to extract the platform44from the female connector12, the shuttle136is moved in the direction174, leftward as shown inFIGS. 4-6.

The engagement and disengagement of the contact headers130and132is accomplished by a series of ramps as indicated previously. The spine140contains plastic ramps142that are molded onto the spine140, so that there is no relative movement—the ramps142are locked to the spine140. The covers150and152contain return ramps154and156, which cause the contact headers130and132to disengage, or move closer to one another. The covers150and152are fixed to the spine140so that these parts move together. All of the ramped surfaces on each respective side of the connector14are parallel. The angles of the ramped surfaces about the centerline of the connector14(the axis of the spine140) are mirror images of one another. This allows the same motion of the contact headers130and132on both sides of the connector14. That is, if the motion of the spine140causes contact header130to move outward, contact header132will also move outward.

The contact headers130and132are constrained in the axis of the motion of the spine140so that as the ramps142are actuated or de-actuated, the only motion available for the contact headers is inward or outward, perpendicular to the surface of the spine140. As the spine140is moved in one direction, the contact headers130and132move outward, away from the spine140. As the spine140is moved in the opposite direction, the contact headers130and132move inward, toward the spine140. This inward motion compresses the platform44, reducing the overall thickness of the platform44. This allows insertion or removal of the platform44from the female contact header12with essentially zero insertion or removal force.

Once the platform44is inserted into the female connector12, the shuttle136may be moved in the direction176, rightward as shown inFIGS. 4-6, to expand the platform44. The ramped inner surfaces154and156engage the header outer ramped surfaces160and162, and press the headers130and132toward one another.

FIGS. 7 and 8illustrate one mechanism for moving the through arm70, and thus moving the shuttle136. The mechanism involves an actuator module178that includes a spring in parallel with a cylinder182. The spring180and the cylinder182are mounted within an actuator body188so as to be able to engage the through arm70, to move selectively the through arm70in opposite directions. The through arm70and the cylinder182are mounted within cavities in the through arm70and the actuator body188. The spring180is mounted in contact with a distal surface190of the through arm70(away from the male connector body60), and a proximal surface192of the actuator body188(relatively close to the male connector body60). Thus spring forces from the compressed spring180tend to push the through arm70away from the male connector body60.

The cylinder182is in contact with a proximal surface194of the through arm70, and a distal surface198of the actuator body188. Thus expansion of the cylinder182tends to urge the through arm70closer to the male connector body60.

FIG. 7shows the position of the components of the system when the cylinder182is not providing any force. The spring180expands in its recess to push the through arm70to the end of its travel. This corresponds to a situation where the platform44(FIG. 1) is expanded, with the male contacts40(FIG. 1) in a position to engage the female contacts90of the female connector12(FIG. 2A). The cylinder182is in a retracted position.

When the cylinder182is extended, the system takes on the configuration shown inFIG. 8. Extension of the cylinder182overcomes the force of the spring180, causing compression of the spring180and movement of the through arm70leftward in the figure. This moves the shuttle136(FIG. 4) so as to cause compression of the platform.

The cylinder182may have any of a variety of means or mechanisms for retracting and/or extending. According to one configuration, the cylinder182includes a polymer material element200. When the polymer material element200is heated, such as by applying suitable electrical current to the element200, it expands, causing the cylinder182to extend. Removal of the current results in cooling of the polymer wire or element200, causing retraction of the cylinder182under the return force of the spring180. One example of a suitable material for the polymer material element200is polyethylene. It will be appreciated that other sorts of cylinders, such as air cylinders, may be used instead of a polymer cylinder. More broadly, actuators using any of a wide variety of forces, such as pneumatic forces or pressurized fluids, may be used to overcome the force of the spring180.

The clearance or float at the link72(FIG. 1), between the pawl73of the through arm70and the mating hole74of the ramp arm68, allows for some lateral movement of the male connector14. Because of the float in the link72, the male connector14has some “float,” which may allow the connectors12and14to self-align to some extent, for example to compensate for individual differences in components.

It will be appreciated that the system described above for moving the through arm70has the advantage of minimal complexity and a small number of moving parts. It is also reliable for repeated operation. Further, it will be appreciated that the mechanism of actuation requires no external force or external energy to maintain the platform44in its expanded state, wherein the male and female contacts engage one another. Further details regarding device test interfaces with such a mechanism may be found in U.S. Pat. No. 6,316,954, which is hereby incorporated by reference in its entirety.

It will be appreciated that a large number of different sorts of actuation mechanisms may alternatively be employed. For example, it will be appreciated that electrical forces, such as a solenoid may be utilized to selectively move the through arm70.

As another alternative, the cylinder182may include a suitable shape memory alloy that expands when heated, allowing extension of the cylinder182by suitable heating of the shape memory alloy. An example of a suitable shape memory alloy is a nickel-titanium alloy. Heating of the shape memory alloy may be accomplished by resistive heating, through connecting the shape memory alloy to a suitable power supply.

It will be appreciated that the connection method described above provides several advantages relative to other methods of electrical connection for use in silicon chip testing. First, insertion forces are minimized by use of the collapsible platform44allowing for zero or very low insertion forces. Second, the female connector described above couples to a board with substantially no net force. In addition, the sheet metal stiffeners in the female connector help prevent deflection of the connector. Further, no external forces or power supplies are required to maintain the male contacts coupled to the female contacts. Rather there is a quiescent coupling due to the action of the spring.

FIG. 9illustrates one possible application for the connectors described above. As shown, a device tester210includes male connectors12and actuator modules178that are mounted in suitable slots as part of a test head212for testing integrated circuits or other devices. The male connectors12may be part of cable assemblies76that may include connectors at both ends. It will be appreciated that due to the large number of connectors that may be involved in a device tester, reducing the insertion force for such connectors would be desirable. Accordingly, it will be appreciated that the zero insertion force connectors described above may be advantageously utilized in such a device tester. Further details regarding device test interfaces may be found in U.S. Pat. No. 6,316,954, which is hereby incorporated by reference in its entirety.

However, it will be appreciated that ZIF connectors such as that described above may be utilized in a wide variety of electrical and electronic interfaces. Suitable modifications may be made with regard to the number, type, and configuration of contacts utilized. Furthermore, it will be appreciated that other types of relative movement of contacts may be utilized to reduce the profile of connectors for zero- or low-force insertion.

FIG. 10illustrates a male connector214that includes a different mechanism, a wavy spring and compressed air, for controlling thickness of its platform244. The platform244includes male contacts240in an array that may be similar to that of the male contacts40of the platform44(FIG. 1), with rows262and264of the contacts240. Guide pins246and248are also similar to corresponding features of the male connector14ofFIG. 1. A cable280includes conductors282that are coupled to the male contacts240, with the male connector214and the cable280together constituting a cable assembly276.

With reference now in addition toFIGS. 11 and 12, the platform244includes a pair of male contact headers330and332that are hingedly coupled together at one end by a pivot pin334. The pivot pin334fits into recesses338in a plastic shell322of a male connector body260. Another similar plastic shell is omitted fromFIG. 10for purposed of illustration. By rotating the headers330and332relative to one another about the pivot pin334, the thickness of the platform244may be altered, bringing together or moving apart the rows262and264of the contacts240.

A resilient device, such as a wavy linear spring350, is used to maintain the contact headers330and332apart from one another when no external force is applied. The spring350, which may be made of a suitable metal such as steel, may be configured to provide a suitable engagement force to cause the male contacts240to engage female contacts90of a corresponding female connector12(FIG. 2A). Although a wavy linear spring is shown, it will be appreciated that a wide variety of types of springs or other types of resilient devices may be used to provide outward force on the contact headers330and332.

In order to reduce the thickness of (compress) the platform244, pressurized gas is introduced into one or more bladders, such as the bladder360, having flexible surfaces in contact with outer surfaces of the male contact headers330and332. The pressurized gas, which may be compressed air supplied by a shop air supply, produces an inward force on the male contact headers330and332. The force of the pressurized gas on the outer surfaces of the male contact headers330and332presses them inward against the force of the spring350toward one another, thereby reducing the thickness of the platform244as the headers330and332rotate about the pivot pin334. With the thickness of the platform244reduced, the platform244may be inserted or removed from a recess of a corresponding female mating connector with substantially zero insertion or removal force. Once the platform244is inserted or removed from the female connector, the pressure in the bladder(s) may be released, causing the spring actuator350to move the headers330and332apart about the pivot pin334, thickening the platform244.

The male connector214may have two bladders, one on each of the headers330and332. The bladders may be in communication with one another. Alternatively, there may be but a single bladder, extending around the outer surfaces of both of the headers330and332. The plastic shells, such as the plastic shell322, have inner surfaces that press inward against outer surfaces of the bladder(s)360. A metal stiffener plate may be included in the male connector214, such as in the plastic shell322, to stiffen and support the plastic case of the connector to resist the force of the pressurized gas in the bladder(s)360.

The cable280may include a gas supply tube362that is laminated alongside the conductors282of the cable280. The gas supply tube362is connected to the bladder(s)360, to provide pressurized gas to the bladder(s)360, and to allow venting of pressurized gas from the bladder(s)360. The gas supply tube362may be coupled to a gas supply, such as a shop air supply of pressurized air.

It will be appreciated that the male connector214has the advantageous properties of a substantially zero insertion and removal force, and of requiring no external force to maintain the male contacts240engaged with corresponding contacts of a female connector. In addition, it will be appreciated that a substantially equal compressing force may be provided on the headers330and332, thus facilitating the platform244being self centering within the male connector214, especially when compressed gas is employed to reduce the thickness of the platform244. Further, including the gas supply tube362as part of the cable280makes the cable assembly276compact, without a need to route a separate gas supply tube to the male connector214.