Electrical interconnect contact system

Abstract: A connector for electrically interconnecting a lead of a device to a terminal spaced at a distance from the lead. The apparatus includes a housing (20) which has a slot (24) to receive one of each of the one or more contacts (22). The contact-receiving slot extends substantially parallel to an axis which extends between a corresponding lead and spaced terminal. The housing has a first trough (56) formed in it proximate the lead and a second trough (58) formed therein proximate the spaced terminal. A first elastomeric element (76) is received in the first trough formed in the housing, and a second elastomeric element (50) is received in the second trough formed in the housing. The first and second elastomeric elements have a measure of compressibility and tensile extendibility. A contact (22) is received within each slot. Each contact provided has a protrusion (42) which extends outward from the surface of the housing to be engaged by the lead to which it corresponds. Each contact also has a nub (40) which extends outward from the surface to engage the corresponding spaced terminal. Each contact also has first and second hook portions, the first hook portion being disposed proximate the contact protrusion and encircling the first elastomeric element to hold the contact to the first elastomeric element, and the second hook portion being disposed proximate the contact nub and encircling the second elastomeric element to hold the contact to the second elastomeric element.

Description: This invention relates to an apparatus for electrically interconnecting a lead of a device to a terminal spaced at a distance from the lead, for example, for interconnecting the leads of an integrated circuit device with corresponding terminals on a printed circuit board interfacing with a tester intended to effect test analysis of the integrated circuit device. The invention also relates to contacts and means for mounting the contacts for effecting such interconnection. Many applications exist for making electrical contact between two conductors. One significant application is the interconnection of leads of an integrated circuit device and conductive pads or terminals on a printed circuit board which serves to effect an interfacing between the integrated circuit (IC) device and a tester apparatus. Such apparatus is used to evaluate performance of integrated circuit devices. Many factors affect the selection of structure for interconnecting the IC and the printed circuit board, including both electrical and mechanical factors. A known interconnection device is known as the Yamaichi contact. It comprises an inverted L-shaped support having a cantilevered contacting portion mounted at the distal end of the generally horizontal leg of the inverted, L-shaped support, and extending generally parallel to that leg. The distal end of the contacting portion is upwardly turned so that a point thereof is engageable by a lead of an integrated circuit device to be contacted. The support, in turn, engages a printed circuit board through a pad or terminal portion. One of the mechanical factors to be taken into account in designing an interconnect system is that a wiping action should be accomplished between the contact itself and the lead of the IC by which the contact is engaged. The wiping action functions to maximize effective contact in view of oxide build up which can occur. In effect, the wiping action enables a good interface to be established between the contact and the lead of the IC. A wiping action can be achieved using the Yamaichi contact because the cantilevered portion is flexible. However, another mechanical factor that must be taken into account is the desire to deter bending of the lead on the IC. The Yamaichi contact does not fully accomplish this goal. Finally with respect to mechanical factors, it is desirable that wiping action can be accomplished at the interface between the second end of the contact and the printed circuit board. This is not possible with the Yamaichi contact because of its construction. Further, the Yamaichi contact does not sufficiently consider the electrical requirements of an interconnecting contact system. An interconnecting contact should be a high speed, short path device. Accordingly, such a contact should have a low inductance without having a controlled impedance requirement. This is not possible with the Yamaichi contact because of its construction. US-4445735 discloses another type of electrical connection device. The device establishes an electrical connection between contacts of a circuit network on a substrate and contact pads of a conductor network on a printed circuit board. This device is an improvement over the Yamaichi contact in that it is higher in speed and lower in inductance than the Yamaichi contact. It has elastomeric means for mounting one or more contacts in a housing. The elastomeric biasing and mounting enables wiping action to be effected at both upper and lower ends of the contact, that is, at both the end which engages an IC lead and the end which engages a printed circuit board contact pad can be wiped across the surfaces intended to be contacted. The device disclosed in US-4445735 has some limitations. While some wiping action is afforded at both upper and lower ends of the contact, the amount of such wiping action is relatively limited because of the elastomeric elements being used generally for effecting biasing rather than free floating suspension of the contacts. As a result of the mounting means incorporated in the disclosed device, there will be a primary tendency for some retraction of the contact point in a generally vertical direction, but there will be only a small component of lateral movement to effect wiping. Additionally, because of the lack of any significant free floating effect, lead bending on an integrated circuit being tested can occur. US-5336094 describes apparatus for electrically interconnecting a lead of a device to a terminal. The apparatus includes a conductive contact mounted on a single elastomeric element and is freely suspended for contact with terminals to be interconnected. A wiping action of the contacts against the terminals is provided by rotation of the contacts. EP-0498530 describes apparatus for electrically interconnecting a lead of a device to a terminal. The apparatus includes a slot in which a contact is mounted on a pair of offset elastomeric elements. The contact is caused to rotate about the offset elastomeric elements so as to wipe a non-elongate part across the terminal when a protrusion at the top of the contact is engaged by the lead of the device. According to a first aspect of the present invention, there is provided apparatus for electrically interconnecting a lead of a device to a terminal spaced at a distance from the lead, comprising: (a) a housing which has at least one contact receiving slot formed therein, the housing having a surface intersected by the at least one contact receiving slot, the at least one contact receiving slot extending substantially parallel to an axis extending between a corresponding lead and spaced terminal; (b) a first elastomeric element carried by the housing such that the first elastomeric element extends across the at least one contact receiving slot; (c) a second elastomeric element carried by the housing. such that the second elastomeric element extends across the at least one contact receiving slot; and (d) a contact received within the at least one contact receiving slot, the contact engagable by the lead and further engagable by the spaced terminal, the contact capturing, and being suspended by, the first elastomeric element and the second elastomeric element, and the contact comprising a first hook member which encircles the first elastomeric element to hold the contact to the first elastomeric element, a second hook member (156B) which encircles the second elastomeric element to hold the contact to the second elastomeric element, a protrusion (154A, 154B) for contacting the lead positioned on a lateral protrusion side of the contact, which extends parallel to an axis extending between the first and second hook members, and proximal the first hook member and an elongated nub extending substantially parallel to an axis perpendicular to the surface of the housing and toward the spaced terminal for contacting the spaced terminal, and the spaced terminal contacting one of the lateral sides of the elongated nub; in which, as the contact is engaged by the lead, the first elastomeric element deforms to permit relative rotation of the contact thereby providing wiping action of the protrusion across the lead of the device, the relative rotation further providing increased force, and to some extent a wiping action, by the elongated nub against the spaced terminal. The downward force exerted by the lead of the integrated circuit upon the contact will have components along both X and Y axes, and these components will effect the apparent rotation of the contact. As a result, the protrusion will move laterally to some degree across the surface of the integrated circuit lead by which it is engaged, and the nub of the contact will move laterally across the integrated circuit board terminal with which it is in contact. The apparatus can have a plurality of slots, each receiving a contact. Typically, a multiplicity of contacts are employed, one for each integrated circuit lead. In such apparatus, the printed circuit board is provided with a plurality of terminals, each engaging one of the ganged contacts. According to a second aspect of the invention there is provided apparatus for electrically interconnecting a lead of a device to a terminal spaced at a distance from the lead, comprising: (a) a housing which has at least one contact receiving slot formed therein, the housing having a surface intersected by the at least one contact receiving slot, the at least one contact receiving slot extending substantially parallel to an axis extending between a corresponding lead and spaced terminal; (b) a first elastomeric element carried by the housing such that the first elastomeric element extends across the at least one contact receiving slot; (c) a second elastomeric element carried by the housing such that the second elastomeric element extends across the at least one contact receiving slot; and (d) a contact received within the at least one contact receiving slot, the contact engagable by the lead and further engagable by the spaced terminal, the contact capturing, and being suspended by, the first elastomeric element and the second elastomeric element, and the contact comprising a first hook member which encircles the first elastomeric element to hold the contact to the first elastomeric element, a second hook member which encircles the second elastomeric element to hold the contact to the second elastomeric element, a protrusion for contacting the lead positioned on a lateral protrusion side of the contact, which extends parallel to an axis extending between the first and second hook members, and proximal the first hook member and an elongated nub comprising a first nub and a second nub extending substantially parallel to an axis perpendicular to the surface of the housing and toward the spaced terminal for contacting the spaced terminal, and the spaced terminal contacting the elongated nub; in which, as the contact is engaged by the lead, the first and second elastomeric elements deform to permit lateral movement of the contact thereby providing wiping action of the protrusion across the lead of the device, and a wiping action, by the elongated nub against the spaced terminal. The first nub and the second nub extend downward from the second surface of the housing to engage a first integrated circuit board terminal and a second integrated circuit board terminal, respectively. As described above, the protrusion on the contact can be positioned lower on the contact body such that the integrated circuit lead contacts the protrusion between the first and the second elastomeric elements. In this embodiment, the downward force exerted by the lead of the integrated circuit upon the contact will have a component along primarily the X axis, and this component will effect lateral movement of the contact. As a result, the first nub and the second nub of the contact can move laterally with respect to the first integrated circuit board terminal and the second integrated circuit board terminal, respectively, thereby providing a wiping action thereto while maintaining contact therewith. This multi-contact embodiment can provide means for programming a corresponding PC board by selectively using the multi-contact in combination with single-contacts. For example, the multi-contact configuration may be used to bridge two signal traces. A test board may be programmed by selecting a multi-contact when two corresponding traces are to be bridged and by selecting a single-contact when two corresponding contacts are not to be bridged. This allows a PC board to be customized by selecting the appropriate combination of multi-contacts and single-contacts, rather than providing a new PC board for each application. The multi-contact may also provide a more reliable contact. In all of the previously described embodiments, a plurality of slots, each receiving a contact, can be provided. Typically, a multiplicity of contacts are used, one for each integrated circuit lead. In such an arrangement, the printed circuit board is provided with a plurality of terminals, each engaging one of the ganged contacts. The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an enlarged fragmentary perspective view of an example prior art apparatus illustrating plural contacts; Figure 2 is a perspective view of an individual contact of the example of Figure 1; Figure 3 is a fragmentary functional diagram showing the example of Figure 1 sectioned vertically and at rest; Figure 4 is a view similar to Figure 3 showing the contact engaged by an integrated circuit device lead; Figure 5 is a view similar to Figure 3 showing the contact being manipulated in order to effect connection or disconnection to the rigid and elastomeric members; Figure 6 is a fragmentary side elevational view of another prior art example with some parts cut away; Figure 7 is an enlarged view similar to Figure 6 showing articulation of a contact in dashed lines; Figure 8 is a fragmentary side elevational view with some parts cut away showing a prior art example in signal mode contact configuration; Figure 9 is a view similar to Figure 8 showing the example in a decoupling mode contact configuration; Figure 10 is a fragmentary side, elevational view with some parts cut away showing another prior art example; Figure 11 is a fragmentary top view of the example of Figure 10; Figure 12 is a fragmentary side elevational view with some parts cut away showing a prior art example in which the lead and spaced terminal lie on a common side of the housing; Figure 13 is a fragmentary side elevational view with parts cut away showing an alternative contact design of the example of Figure 12; Figure 14 is a fragmentary side elevational view of another prior art example with some parts cut away; Figure 15 is a fragmentary side elevational view of the housing shown in Figure 14 with some parts cut away; Figure 16 is a side view of an individual contact of the example shown in Figures 14 and 15; Figure 17 is a fragmentary side elevational view of an embodiment of a first aspect of the invention with some parts cut away; Figure 18 is a fragmentary side elevational view of another embodiment of the first aspect of the invention with some parts cut away; and Figure 19 is a side view of a lower portion of an individual contact of an embodiment of a second aspect of the invention. Referring now to the drawings in which like reference numerals denote like elements throughout the several views, Figure 1 shows apparatus which comprises a housing 20 suspending a plurality of contacts 22. The housing 20 shown in Figure 1 is representative of a housing usable in virtually all embodiments of the invention, although, in some embodiments, some variations, generally unrelated to contact mounting, could be incorporated. Some portions of the housing 20 are broken away in Figure 1, but one viewing the figure can count at least seven slots 24 formed through the housing 20. The rightmost of the slots 24 is sectioned so that only one side wall 26 of the slot 24 is able to be seen. While seven slots 24 are illustrated, only four contacts 22 are shown as being disposed in slots 24. It will be understood, however, that a contact 22 would typically be suspended within the housing 20 in each slot 24 provided, although this would not be essential. Additionally, it will be understood that any number of slots 24 could be provided, and the slots 24 could be organized in multiple arrays. For example, four arrays of slots 24 defining a quadrilateral form could be employed. Such a configuration would be employed when the housing 20 in accordance with the present invention is intended to interconnect a printed circuit board 2B, interfacing with a tester mechanism (not shown), to the leads 30 of, for example, of a leadless chip carrier integrated circuit device 32. Figure 1 is therefore merely illustrative of a basic construction of housing 20 in accordance with the invention. As seen in Figure 1, the rightmost slot 24 is shown as extending fully through the vertical dimension of the housing 20 from a first, upwardly facing surface 34 of the housing 20, to a second downwardly facing surface 36 of the housing 20. The same is true of each slot 24. The second surface 36 of the housing 20 is shown as being in engagement with a printed circuit board 28 having at least one pad or terminal 38 traced thereon. Such a pad 38 is intended to be engaged by a nub 40 at the lower end of the contact 22 as will be discussed hereinafter. In view of the fact that the nub 40 is biased to extend outwardly at least to the second surface 36 of the housing 20, when the printed circuit board 28 is held in position in engagement with the second surface 36 of the housing 20, the nub 40 of the contact will, in fact, engage the pad 38 if the pad 38 is properly positioned spatially. Figures 6 and 7, to which further reference will be made in describing the prior art example, show a contact 22' suspended in a housing 20 in a manner discussed hereinafter. The contact 22' has a small measure of elongation and has a protrusion 42 at its upper end, the protrusion 42 functioning to be engaged by a lead 30 from an integrated circuit device 32 intended to be interconnected to the printed circuit board 28. As seen in Figure 6 and 7, when the contact 22' is suspended by the housing 20, the protrusion 42 extends upwardly beyond the first surface 34 of the housing 20. As previously discussed, the contact 22' has a nub 40 at its lower end. The nub 40 is, of course, intended to engage the terminal or pad 38 on the printed circuit board 28 which corresponds to a particular integrated circuit lead 30 engaged by the protrusion 42 of the respective contact 22. Proximate the nub 40 is a hook portion 44 of the contact 22'. The hook portion 44 defines a generally circular aperture 46 which is pinched at the entry thereto, as at 48, so that, when the hook portion 44 is urged over an elastomeric element 50 as defined hereinafter, the contact 22' will be maintained in a position suspended with respect to the elastomeric element 50. The contact 22', proximate its upper protrusion end, is provided with an elongated channel 52. This channel 52 is intended to receive a rigid element 54 as defined below. Referring again to Figure 1 which shows a representative housing 20, the first surface 34 of the housing 20 is provided with a trough 56, that trough 56 extending across, and generally transverse to, the plurality of slots 24. In a like manner, the second surface 36 of the housing 20 also has a trough 58 formed therein. This trough 58 also extends across the various slots 24 and is illustrated as being generally transverse to the direction of orientation of the slots 24. Each trough 56, 58 is shown as being generally symmetrical with respect to an imaginary plane 60 that would be perpendicular to the respective surface in which the trough 56, 58 is formed. It will also be noted that the troughs 56, 58 are laterally offset from one another for a purpose that will become apparent in view of subsequent discussion. The trough 56 formed in the first surface 34 is intended to accept the rigid element 54 in the case of the example of Figures 6 and 7. The element 54 is shown as extending fully across the array of slots 24 across which the trough 56 in which the element 54 is received extends. In that example, the trough 58 formed in the second surface 36 of the housing 20 is intended to accept a compressible, tensile extendable, elastomeric element 50 therein. In the case of the rigid element 54 received in the trough 56 formed in the first surface 34 of the housing 20, the elastomeric element 50 received in the trough 58 formed in the second surface 36 of the housing 20 is intended to extend fully across the array of slots 24 across which the trough 58 in which the elastomeric element 50 is received extends. Mounting, or suspension, of individual contacts 22' in the example of Figures 6 and 7 can be effected in any appropriate manner. One simple manual way of effecting suspension would be to insert the contact 22' downwardly through the slot 24 within which it is to be received by urging the nub 40 end between the rigid element 54 and the elastomeric element 50, those two members having been received within their respective troughs 56, 58. Once the hook portion 44 has been inserted to a point at which it has achieved a location below the elastomeric element 50, the hook portion 44 can be moved laterally to "catch" the elastomeric element 50 within it. After such "catching" has occurred, the contact 22' would be withdrawn upwardly to a point at which the entrance to the elongated channel 52 in the contact 22' is above the upper edge of the rigid element 54. The protrusion end of the contact 22' can then be moved in a direction to the right, as viewed in Figures 6 and 7, until the entrance 62 to the channel 52 is above the rigid element 54. It will be understood that, as the contact 22' is withdrawn upwardly, the elastomeric element 50 will come under tension when the contact 22' is in a disposition wherein the entrance 62 to the channel 52 is above the rigid element 54. When the contact 22' is in such a disposition, the contact 22' can be eased downwardly so that the rigid element 54 enters the channel 52. The tension on the elastomeric element 50 will, thereby, be released, and the contact 22' will be in its "rest" position. This procedure can be performed for multiple contacts 22' when a gang or array of contacts 22' is employed. The "rest" position of a contact 22' is represented in solid line in Figure 7. The centre-line axis 64 of the channel 52 is angled slightly to the right of a plane of symmetry 60 to the trough 56 within which the rigid element 54 is received. That plane of symmetry 60 is generally normal to the first surface 34 of the housing 20 and is represented by a dashed line. The centre-line axis 64 of the channel 52 formed in the contact 22' is represented by an additional line 64 in Figure 7 at a slight angle with respect to the line representing the plane of symmetry 60 of the trough 56. An angle representation 66 indicates the angle at which the channel 52 is tilted from the plane of symmetry 60 of the trough 56. This angle 66 can be, in the "rest" position of the contact 22', quite small and probably, it is anticipated, of a magnitude of between about 3° and 30°. Figure 7 also illustrates the movement of a contact 22' as the protrusion 42 of the contact 22' is engaged by a lead 30 of an integrated circuit device 32. As the integrated circuit device 32 is brought into engagement with the protrusion engagement point and downward pressure continues, the rigid element 54 rides upwardly, relative to the elongated channel 52 in the contact 22', and the angle of offset 66 of the axis 64 of the channel 52 becomes more exaggerated. As this occurs, the engagement point of the protrusion 42 is moved downwardly and to the right. The rightward movement of the engagement point of the protrusion 42 will permit relative movement of the engagement point across the surface of the integrated circuit lead 30. This wiping action will provide for a better electrical flow path between the integrated circuit lead 30 and the protrusion 42 of the contact 22'. One of the reasons why the apparent rotation of the contact 22' will occur is that the nub end of the contact 22' will be precluded from downward movement by the terminal or pad 38 of the printed circuit board 28. As previously discussed, in the example illustrated in Figures 6 and 7, the printed circuit board 28 is substantially in engagement with the second surface 36 of the housing 22'. The vertical location of the deepest part of the trough 58 formed in the second surface 36 of the housing 20 relative to the dimensions of the lower portion of the contact 22' will provide for biasing of the nub 40 of the contact 22' into engagement with the printed circuit board pad 38. As the integrated circuit 32 urges the protrusion 42 of the contact 22' downwardly, therefore, the nub 40 will be driven in a direction to the left as viewed in Figure 7. Wiping action will, thereby, occur, and the electrical flow path between the nub 40 of the contact 22' and the printed circuit board terminal 38 will be optimized. Figures 8 and 9 show contacts and contact suspension means as illustrated in Figures 6 and 7 to illustrate signal and decoupling modes of the housing 20. Figure 8 illustrates the example in a signal mode configuration. This view shows the contacts 22' configured to interface signal terminals or lands 68 on the printed circuit board 28. Figure 9 illustrates a decoupling mode. In the decoupling mode, the integrated circuit device 32 has multiple ground and, sometimes, multiple power leads which need to be connected by a capacitor 70 to allow current response when outputs of the integrated circuit device 32 are switched. In the prior art, the customer is assisted in meeting needs for specific device configurations of ground and power locations. These locations are virtually always located near the centre of the sides, since the internal lead inductance is the smallest. The housing 20 is designed to permit centre contacts to be mirrored to allow ground and power leads to directly contact one of multiple decoupling planes 72. Each decoupling plane 72 used is designated as either a ground or power plane so that, when a chip capacitor 70 is soldered ,across these planes 72, a decoupling circuit will be formed. Both the signal terminals or lands 68 and the decoupling planes 72 are connected to external customer circuits. The contacts 22' are shown as mirrored to allow for direct integrated circuit electrical connection to the decoupling planes 72. The decoupling planes 72 are decoupled by a chip capacitor 70. The contacts 72 illustrated in Figures 1 to 5 are different than those illustrated in Figures 6 and 7. Figure 2 illustrates an alternative form contact 22 isolated from a slot 24 within the housing 20. The primary difference between this contact 22 and that previously described is that the contact 22 does not have an elongated channel 52 proximate the upper protrusion portion. Rather, the contact 22 of Figures 1 to 5 is provided with a hook portion 74 similar to the hook portion 44 proximate the nub 40 of the contact example previously described. When the contact 22 illustrated in Figures 1 to 5 is employed, a different type of element 76 would be seated in the trough 56 formed in'the first, or upper, surface 34 of the housing 20. Rather than providing a rigid element 54, the element 76 which would be received in the trough 56 in the first surface 34 of the housing 20 in this example would be elastomeric in nature and similar to the element 50 in the trough 58 formed in the second surface 36 of the housing 20. Both elements would, therefore, have a measure of compressibility and tensile extendibility rather than only one element having such compressibility and tensile extendibility, as is the case with the example of Figures 6 and 7. With both elements being elastomeric in nature, movement of both the protrusion 42 and the nub 40 of the contact 22 would still be able to occur along two mutually to perpendicular axes. That is, both the protrusion 42 and the nub of the contact 22 could move generally horizontally and vertically in view of the compressibility of the two elements. The example of Figures 1 to 5, therefore, would also achieve the desired wiping action. At the same time, integrated circuit lead damage would be minimized, since the contact 22 is substantially free-floating in its suspension within the housing 20. It will be understood that the response of the system can be controlled by varying the hardness (durometer) rating of the element 76 received within the trough 56 formed within the upper surface 34 of the housing 20. The harder that the element 76 is, the more resistant it will be to lateral motion of the contact protrusion 42, and wiping action of protrusion 42 across the lead 30 of an integrated circuit 32 will be reduced. A typical durometer range is between 30 and 90 Shore D. Figure 3 illustrates the contact 22 of the example of Figures 1 to 5 in its normal "rest" position. In this position, both elastomeric elements 50, 76 extend substantially linearly. Figure 5 illustrates the manner in which the elastomeric elements 50, 76 could be manipulated in order to effect mounting. Figure 5 shows a contact 22 having been inserted upwardly through the bottom, second surface 36 of the housing 20 so that the protrusion 42 of the contact 22 passes between the two elastomeric elements 50, 76 and the hook portion 74 proximate the protrusion 42 of the contact 22 is positioned above the elastomeric element 76 received in the trough 56 formed in the first surface 34 of the housing 20. The upper hook portion 74 then is brought downwardly to "catch" the elastomeric element 76 received in the trough 56 formed in the first surface 34 of the housing 20. Figure 5 illustrates the contact 22 with such attachment to the elastomeric element 76 received in the trough 56 formed in the first surface 34 of the housing 20 being drawn downwardly to deform that element 76 so that the lower hook portion 44 can be brought into a disposition at which it can "catch" the elastomeric element 50 received in the trough 58 formed in the second surface 36 of the housing 20. When the lower hook portion 44 is brought into such a position, the contact 22 can be gradually released to effect catching of the elastomeric element 50 received in the trough 58 formed in the second surface 36 of the housing 20. After this occurs, the contact 22 and the elastomeric elements 50, 76 assume the positions illustrated in Figure 3. Figure 4 illustrates the response of the assembly when the lead 30 of an integrated circuit 32 is brought into engagement with the protrusion 42 of the contact 22. As can be seen, the elastomeric element 76 received in the trough 56 formed in the first surface 34 of the housing 20 is deformed downwardly as it undergoes compression and tensile extension. With the nub 40 of the-contact 22 in engagement with the terminal 38 on the printed circuit board 28, there will be a deformation of the elastomeric element 50 received in the trough 58 formed in the second surface 36 of the housing 20. As seen in Figure 4, this deformation will have an apparent upward movement. In the example illustrated in Figures 1 to 5, the printed circuit board 28 might, initially, be spaced from the second surface 36 of the housing 20. As the lead 30 of the integrated circuit device 32 is brought into engagement with the protrusion 42 of the contact 22 to urge the protrusion 42 downwardly, the lower extremity of the contact 22 (that is, the nub 40) will come into engagement with the terminal 38 of the printed circuit board 28. As continued downward movement of the protrusion 42 of the contact 22 occurs, co-related upward movement of the nub 40 will result. This movement of the contact 22 will function to accomplish wiping and protection of the integrated circuit lead 30. Figures 10 and 11 illustrate an example akin, in some respects, to the example of Figures 6 and 7. In this example, a rigid element 54 is employed and is received in the elongated channel 52 of each of a plurality of contacts 22'. In this example, however, contacts 22' in adjacent slots 24 are staggered. That is, while one contact 22' extends to the left as seen in Figure 10, the next contact 22' extends to the right. It will be understood, and it is illustrated in Figures 10 and 11, that an additional elastomeric element 78 is provided, since hook portions 44 of the various contacts 22' in the array extend on two sides of the central, rigid element 54. In order to accommodate the additional elastomeric element 78, a second trough 80 is formed in the second surface 36 of the housing 20. The trough 80 would be spaced laterally from an intended location of the rigid element 54 substantially the same distance that the initial elastomeric element 50 is spaced in an opposite direction. As a result, the contact array will appear symmetrical. This arrangement is best seen in Figure 10. In the example of Figures 10 and 11, a trough need not be provided in the first surface 34 of the housing 20 to receive the rigid element 54. Because of the oppositely co-acting contacts, the rigid element 54 can be received in various elongated channels 52 in the contacts 22', and the reciprocal cooperation of the contact channels 52 will result in a jaw effect whereby the rigid element 54 is held in the channels 52. Since a trough need not be provided for receipt of the rigid element, material need not be expended in forming the housing 20 at the location where the rigid element 54 is disposed. As seen in Figure 10 then, a generally V-shaped recess 82 can be formed in the housing 20 with a central wall 84 extending upwardly from the second surface 36 of the housing 20 to separate left and right slots 24. Material from which the housing 20 as formed can, thereby, be conserved. As seen in Figure 11, the slots 24, typically, have an axial dimension greater than that of the respective contacts 22'. Consequently, there can be some play with the contacts 22' not being maintained in continuously defined planes. Since the contacts 22' are conductive in nature, insulating washers 86 can be disposed between adjacent contacts 22' along the rigid element 54. The axial dimension of the washers 86 can be such that play among the contacts 22' can be minimized. Figure 10 illustrates an integrated circuit device 32 with its leads 30 being brought into engagement with the protrusions 42 of the various contacts 22'. Figure 10 illustrates those leads 30 as being spaced laterally in order to conform to the positions of the protrusion 42 of the contacts 22'. In fact, it will be understood that the slots 24 and respective contacts 22' received therein can be constructed in a manner so as to accommodate integrated circuits 32 structured in any particular fashion. Next referring to Figure 12 and 13, an alternative example is depicted. This alternative example is directed to a specific design in which the apparatus is used for electrically interconnecting a lead of a device to a terminal spaced laterally at a distance from the lead on the same side of a housing. In this example, the contact is designed with the nub and protrusion extending beyond a common planar surface 100 of the housing 20. As depicted in Figure 12, in this alternative example, a housing 20, as previously described, having a slot, extending substantially parallel to an axis extending between a corresponding lead and spaced terminal, is provided. The housing 20 has a lateral surface (not shown), having a first trough 102 formed therein to extend proximate a lead 103. An opposite lateral surface (not shown) has a second trough 104 formed therein to extend proximate the spaced terminal 105. A first elastomeric element 106 is received within the first trough 102. A second elastomeric element 107 is received in the second trough 104. Both elastomeric elements have a measure of compressibility and tensile extendibility. A contact 110, which generally defines a plane, is received within the slot 24. The contact has a protrusion 111 extending outward from the surface 100 for engagement by the lead 103. The generally planar contact 110 also has a nub 112 extending outward from the surface 100 for engagement with the spaced terminal 105. Both the nub 102 and the protrusion 111 lie generally within the same plane in example of Figure 12. Figure 13 shows an example similar to that of Figure 12. The contact 120, however, is of a different design and is made from a spring form. The contact 110 of Figure 12 includes a nub 112 and protrusion 111 which are integral extensions of the contact, as manufactured, proximate each of respective hook portions 108, 109. An example of integral extensions, is where, during the manufacture of the contact, the nub and protrusions are cut or formed from the contact material during manufacture such as stamping or cutting. In contrast, the contact 120 of Figure 13 includes a nub 122 and protrusion 124 which are formed by bending the spring form contact proximate each of similarly formed hook portions 126, 128. As with other examples, the protrusion is engaged by a lead and the first and second elastomeric elements function to permit movement of the contact in directions along two mutually perpendicular axes wherein beneficial wiping action of the protrusion across the lead and the nub across the spaced terminal occurs. It should be noted that, in the example illustrated in Figure 13, the troughs 130, 132 in which the elastomeric elements are received are formed into the housing entering from surface 100 but at an angle thereto. The angles of entry are such that, when the contact 120 is hooked over the elastomeric elements, those elements will be retained within troughs 130, 132. Regardless of the embodiment of the invention, the housing 20 is substantially the same, varying only based upon the intended location of the contacts 22', 110, 120 and the location of trough entry. The housing 20 can be fabricated by forming the slots 24 with either laser machining (typically, for prototyping and small production quantities) or injection moulding of the overall housing 20 with slots 24 formed therein (typically, for economic production quantities). Contacts 22, 22', 110, 120 can be suspended in a manner previously discussed. As one will perceive, contacts 22, 22', 110, 120 are individually replaceable. The contacts 22, 22', 110, 120 are designed to provide very short electrical paths. Typically, the overall length of a contact would not exceed about 3.5 mm (0.14 in). In contacts in accordance with the present invention, such a length translates into a 2.0 nH inductance between surfaces. As a result, very high digital signals (typically greater than 5 GHz) can be transmitted without any significant loss of fidelity. Since the areas of the contacts 22, 22', 110, 120 which actually engage integrated circuit device leads 30 and printed circuit board terminals 38 is minimal, the amount of cross to talk between signal lines will also be minimal. This will provide for higher isolation of transmitted analog signals. Figures 14 to 16 show another example. The housing of the present embodiment is similar to the housing shown in Figure 1 except that the first trough and the second trough are aligned as shown in Figure 15. That is, a first trough 170 may be formed in the first surface 172 of housing 168 and a second trough 174 may be formed in the second surface 176 of housing 168. The first trough 170 may be substantially aligned with the second trough 174 such that the first trough 170 and the second trough 174 may intersect a plane which is normal to the first surface 172 and the second surface 176 of the housing 168. In many other respects, the housing 168 may be similarly constructed to that shown and described in Figure 1. For example, a plurality of slots may be provided therein for receiving a plurality of integrated circuit device leads. One such slot is shown at 178 of Figure 15. A first elastomeric elongated element 180 may be placed in the first trough 170, and a second elastomeric elongated element 182 may be placed in the second trough 174. In an exemplary example, it is contemplated that the second elongated element 182 may be constructed from a material having a higher durometer rating than that of the first elastomeric elongated element 180 and still be within the scope of the present invention. The contact 150 of the present example may be of a different design than that shown in Figures 6 and 7. The contact of the present example is generally shown at 150. Contact 150 may include a nub 152 extending downward from the second surface 176 of the housing 168 for engagement of the spaced terminal and a protrusion 154 extending into a slot 178 in the housing 168 for engagement of the lead. The nub 152 and the protrusion 154 may be integral extensions of the contact 150, as manufactured, wherein the nub 152 may be positioned near the lower portion of the contact 150 and the protrusion 154 may be positioned near an upper-side portion of the contact 150. The protrusion 154 may be adjacent to a first hook member 156. A second hook member 158 may be positioned below the first hook member 156 but above the nub 152. The first hook member 156 and the second hook member 158 may each have an opening 162 and 164, respectively. Openings 162 and 164 may open to the opposite side of the contact 150 as the protrusion 154. Further, the first hook member 156 may be separated from the second hook member 158 by a contact centre portion 160. The first hook member 156 may capture the first elastomeric elongated element 180 and the second hook member 158 may capture the second elastomeric elongated element 182. The contact 150 would, therefore, latch onto the first elastomeric elongated element 180 and the second elastomeric elongated element 182. The first and second elastomeric elongated elements may hold the contact in place, as previously disclosed. As a particular lead 190 of an integrated circuit device 192 engages the protrusion 154 of a corresponding contact 150 and exerts downward pressure upon the protrusion 154 , the contact 150 may move relative to the first elastomeric elongated element 180 and the second elastomeric element 182 captured therein, and the contact 150 may, effectively, be made to rotate to some extent as a result of the first elastomeric elongated element 180 deforming laterally away from the lead 190 of the integrated circuit 192. That is, the downward force exerted by the lead 190 of the integrated circuit 192 upon the contact 150 may have components along both X and Y axes, and these components may effect the apparent rotation of the contact 150. As a result, the protrusion 154 will move laterally to some degree across the surface 196 of the integrated circuit lead 190 by which it is engaged, and the nub 152 of the contact 150 may move laterally across the integrated circuit board terminal 194 with which it is in contact. It is contemplated that the second elastomeric elongated element 182 may be constructed from a material having a higher durometer rating than that of the first elastomeric elongated element 180 and still allow the apparent rotation of contact 150. An embodiment of the present invention is shown in Figure 17. This embodiment is similar to the examples shown in Figures 14 to 16, but a contact 150A may have an elongated nub 200 extending downward from the second surface 176 of the housing 168. An integrated circuit board terminal 202 may be positioned to engage a side 204 of the elongated nub 200 opposite the first and second hook members 156A and 158A. In this embodiment, as in the previously described related examples, the downward force exerted by the lead of the integrated circuit upon the contact 150A will have components along both X and Y axes, and these components will effect the apparent rotation of the contact 150A. As a result, the protrusion 154A may move laterally to some degree across the surface of the integrated circuit lead by which it is engaged. Further, the extended nub 200 of the contact 150A may tend to move laterally with respect to the integrated circuit board terminal 202 thereby applying increased force thereon. The apparent rotation of the contact 150A may also cause the elongated nub 200 to move somewhat vertically across the integrated circuit board terminal 202 thereby providing a wiping action thereto. In another embodiment of the present invention as shown in Figure 18, a contact 150B may have an elongated nub 210 extending down from the second surface 176 of the housing 168 as previously described. However, the integrated circuit board terminal 212 may be positioned to engage a side 214 of the elongated nub 210 which is adjacent to the first and second hook members 156B and 158B. Further, the protrusion 154B on the contact 150B may be positioned lower on the contact body such that a corresponding integrated circuit lead contacts the protrusion between the first elastomeric elongated element 180 and the second elastomeric elongated element 182. In this embodiment, the downward force exerted by the lead of the integrated circuit upon the contact 150B will have a component along primarily the X axis, and this component will effect the apparent lateral movement of the contact 150B. As a result, the extended nub 210 of the contact 150B may tend to move laterally with respect to the integrated circuit board terminal 212 thereby applying increased force thereon. It is contemplated that the elongated nub 210 of the contact 150B in the previously described embodiment may be replaced with a first nub 220 and a second nub 222 as shown in Figure 19. The first nub 220 and the second nub 222 may extend downward from the second surface 176 of the housing 168 for engagement of a first integrated circuit board terminal 224 and a second integrated circuit board terminal 226, respectively. The first and second integrated circuit board terminals 224 and 226 may be on a PC board 225. As described above, the protrusion 154B on the contact 150B may be positioned lower on the contact body such that the integrated circuit lead contacts the protrusion 154B between the first elastomeric elongated element 156B and the second elastomeric elongated element 158B. In this embodiment, the downward fprce exerted by the lead of the integrated circuit upon the contact 150C will have a component along primarily the X axis, and this component will effect the lateral movement of the contact 150C. As a result, the first nub 220 and the second nub 222 of the contact 150C tend to move laterally with respect to the first integrated circuit board terminal 224 and the second integrated circuit board terminal 226, respectively, thereby providing a wiping action thereto while maintaining contact therewith. This multi-contact 150C embodiment may provide a means for programming a corresponding PC board by selectively using the multi-contact 150C in combination with single-contacts 150. For example, the multi-contact 150C configuration may be used to bridge two signal traces 224 and 226. A test board may be programmed by selecting a multi-contact 150C when two corresponding traces are to be bridged and by selecting a single-contact 150 when two corresponding contacts are not to be bridged. This allows a PC board to be customized by selecting the appropriate combination of multi-contacts 150C and single-contacts 150, rather than providing a new PC board for each application. The multi-contact 150C may also provide a more reliable contact. As stated above, regardless of the embodiment of the invention, the housing 168 may be substantially the same, varying only based upon the intended location of the contacts 22', 110, 120, 150, 150A, 150B, 150C and the location of trough entry. The housing 168 can be fabricated by forming slots 178 with either laser machining (typically, for prototyping and small production quantities) or injection moulding of the overall housing 168 with slots 178 formed therein (typically, for economic production quantities). Contacts 22, 22', 110, 120, 150, 150A, 150B, 150C can be suspended in a manner previously discussed. As one will perceive, contacts 22, 22', 110, 120, 150, 150A, 150B, 150C are individually replaceable. Further, the contacts 22, 22', 110, 120, 150, 150A, 150B, 150C are designed to provide very short electrical paths. Typically, the overall length of a contact would not exceed 3.5 mm(0.14 in). In contacts in accordance with the present invention, such a length translates into a 2.0 nH inductance between surfaces. As a result, very high digital signals (typically greater than 5 GHz) can be transmitted without any significant loss of fidelity. Since the areas of the contacts 22, 22', 110, 120, 150A, 150B, 150C which actually engage integrated circuit device leads 190 and printed circuit board terminals 194 is minimal, the amount of cross to talk between signal lines will also be minimal. This will provide for higher isolation of transmitted signals. Finally, as discussed above, a plurality of slots, each receiving a contact, may be provided. Typically, a multiplicity of contacts are employed, one for each integrated circuit lead. In such an embodiment, the printed circuit board is provided with a plurality of terminals, each being in engagement with one of the ganged contacts. Changes can be made in details, particularly in matters of shape, size, and arrangement of parts of the apparatus described above.

Claims: Apparatus for electrically interconnecting a lead (190) of a device (192) to a terminal (202, 212) spaced at a distance from the lead, comprising: (a) a housing (20, 168) which has at least one contact receiving slot (24) formed therein, the housing having a surface (172, 176) intersected by the at least one contact receiving slot, the at least one contact receiving slot extending substantially parallel to an axis extending between a corresponding lead and spaced terminal; (b) a first elastomeric element (180) carried by the housing such that the first elastomeric element extends across the at least one contact receiving slot; (c) a second elastomeric element (182) carried by the housing such that the second elastomeric element extends across the at least one contact receiving slot; and (d) a contact (150A, 150B) received within the at least one contact receiving slot, the contact engagable by the lead and further engagable by the spaced terminal, the contact capturing, and being suspended by, the first elastomeric element and the second elastomeric element, and the contact comprising a first hook member (156A) which encircles the first elastomeric element to hold the contact to the first elastomeric element, a second hook member (156B) which encircles the second elastomeric element to hold the contact to the second elastomeric element, a protrusion (154A, 154B) for contacting the lead positioned on a lateral protrusion side of the contact, which extends parallel to an axis extending between the first and second hook members, and proximal the first hook member and an elongated nub (200, 210) extending substantially parallel to an axis perpendicular to the surface (172, 176) of the housing and toward the spaced terminal for contacting the spaced terminal, and the spaced terminal contacting one of the lateral sides (204, 214) of the elongated nub; in which, as the contact is engaged by the lead, the first elastomeric element deforms to permit relative rotation of the contact thereby providing wiping action of the protrusion (154A, 154B) across the lead of the device, the relative rotation further providing increased force, and to some extent a wiping action, by the elongated nub (200, 210) against the spaced terminal. Apparatus as claimed in claim 1, in which the first elastomeric element (180) is constructed from a material that is less deformable than the second elastomeric element (182). Apparatus as claimed in claim 1, in which the second elastomeric element (182) is constructed from a material that is less deformable than the first elastomeric element (180). Apparatus as claimed in any preceding claim, in which the first and second elastomeric elements deform as the contact (150A, 150B) is engaged by the lead to permit lateral movement of the contact. Apparatus as claimed in any preceding claim, in which the housing (168) has a first trough (170) formed therein proximate the lead and a second trough (174) formed therein proximate the spaced terminal, the first trough (170) receiving the first elastomeric element and the second trough (174) receiving the second elastomeric element. Apparatus as claimed in claim 5, in which the first trough (170) and the second trough (174) intersect a plane which is normal to the surface (172, 176) of the housing. Apparatus as claimed in any preceding claim, in which the elongated nub (200, 210) and the protrusion (154A, 154B) on the contact are integral extensions of the contact. Apparatus as claimed in claim 1, in which the protrusion (154B) is positioned between the first hook member (156B) and the second hook member (158B) on the lateral protrusion side of the contact such that as the contact is engaged by the lead, the first and second elastomeric elements (180, 182) deform to permit lateral movement of the contact thereby providing wiping action of the protrusion across the lead of the device and the elongated nub across the spaced terminal. Apparatus as claimed in claim 1, in which a side (214) of the elongated nub opposite to the lateral protrusion side of the contact contacts the spaced terminal (212). Apparatus for electrically interconnecting a lead (190) of a device (192) to a terminal (224, 226) spaced at a distance from the lead, comprising: (a) a housing (20, 168) which has at least one contact receiving slot (24) formed therein, the housing having a surface (172, 176) intersected by the at least one contact receiving slot, the at least one contact receiving slot extending substantially parallel to an axis extending between a corresponding lead and spaced terminal; (b) a first elastomeric element (180) carried by the housing such that the first elastomeric element extends across the at least one contact receiving slot; (c) a second elastomeric element (182) carried by the housing such that the second elastomeric element extends across the at least one contact receiving slot; and (d) a contact (150C) received within the at least one contact receiving slot, the contact engagable by the lead and further engagable by the spaced terminal, the contact capturing, and being suspended by, the first elastomeric element and the second elastomeric element, and the contact comprising a first hook member (156A) which encircles the first elastomeric element to hold the contact to the first elastomeric element, a second hook member (156B) which encircles the second elastomeric element to hold the contact to the second elastomeric element, a protrusion (154A, 154B) for contacting the lead positioned on a lateral protrusion side of the contact, which extends parallel to an axis extending between the first and second hook members, and proximal the first hook member and an elongated nub comprising a first nub (220) and a second nub (222) extending substantially parallel to an axis perpendicular to the surface (172, 176) of the housing and toward the spaced terminal for contacting the spaced terminal, and the spaced terminal contacting the elongated nub; in which, as the contact is engaged by the lead, the first elastomeric element deforms to permit relative rotation of the contact thereby providing a wiping action of the protrusion (154A, 154B) across the lead of the device, the relative rotation further providing increased force, and to some extent a wiping action, by the elongated nub against the spaced terminal. Apparatus as claimed in claim 10, the first nub contacting a first spaced terminal (224) and the second nub contacting a second spaced terminal (226), as the contact (150C) is engaged by the lead, the first and second elastomeric elements deform to permit lateral movement of the contact thereby providing wiping action of the protrusion across the lead of the device, the lateral movement further providing wiping action of the first and second nubs across the first and second spaced terminals, respectively. Apparatus as claimed in claim 11, in which the contact (150C) having the first nub (220) and the second nub (222) can be selectively used to program a corresponding PC board. Apparatus as claimed in any preceding claim, in which the first elastomeric element and the second elastomeric element have a measure of compressibility and tensile extendibility.

Inventors: JOHNSON DAVID A, JOHNSON, DAVID A.
Applicants: JOHNSTECH INT CORP, JOHNSTECH INTERNATIONAL CORPORATION
Application year: 1995
Main classification: H01R12
IPC codes: G01R31, H01R12, G01R1, H01L23, H01R33, H05K7, H01R24, H01R13