GB2273830A - Electrical contact elements for interposer structures - Google Patents

Abstract

A contact element (300, fig. 1), comprises two contact sections (301, 302) dimensioned to resist deflection by different amounts. Respective bights (312, 315) of spring loops of the contact sections have differing sizes. A plurality of such contacts may be mounted in an interposer, fig. 9, for insertion between circuit boards. The contact sections (301, 302) may be plated with gold or tin. <IMAGE>

Description

ELECTRICAL CONTACT ELEMENTS FOR INTERPOSER STRUCTURES This invention relates to electrical contact elements for interposer structures, and to interposer contact modules and land grid contact arrays comprising such contact elements.

With the present trend towards the miniaturization of electrical components and the high contact density involved, there are increasing demands upon the reliability of contact elements for use in such components.

Modern ultrasound diagnostic equipment, for example, typically includes a connector system for interfacing an electronic device in a base unit with a transducing device which interfaces with the patient's body. Such connector systems generally comprise an electrical interface for busing signals from the transducer to the base unit for analysis and data processing. Radar equipment, computer equipment in general, and other electronic devices may also have similar interfaces, which may be most complex.

In order to achieve high integrity data communications between an outside source of data and an electronic device, connectors have been designed to accommodate high density contact elements so that increased data flow through the connector at high frequencies and at high speeds can be achieved.

Examples of such connectors and connector systems are disclosed in USA-4,699,593, US-A-4,927,369 and US-A4,647,124.

In such connectors two electrical components, typically two printed wiring boards, are interconnected by means of a system of contacts sometimes referred to as a land grid contact array, which comprises an interposer structure. Connectors of this type are usually "one-shot" connectors in that they are permanently assembled in mated relationship to the electronic device, and are not adapted for repeated mating and unmating.

An interposer structure typically comprises an insulating housing having cavities therein for receiving electrical contact elements. The contact elements have contact surfaces which project from opposite surfaces of the interposer structure.

The contact elements discussed in US-A-4,927,369, for example, comprise a pair of identical, loop-shaped contact springs arranged in rotational symmetry and being connected to one another by a bight portion. In use, the interposer structure is disposed between the two electrical components and contact surfaces of the electrical components and the interposer structure are moved relatively towards one another. As the contact pads of the electrical components mate with the opposing contact surfaces of the contact elements of the interposer structure, the contact springs of the contact elements resist the mating movement and thereby provide a required contact force at the interface between each pad and the respective contact surface of a contact element of the interposer structure.The contact force exerted by each contact surface on its associated contact pad is substantially identical, and this is also true of the contact elements of the interposer structure disclosed in the other patent specifications cited above.

The present invention is intended to provide a contact element which can be used in an interposer structure which is fixed to one of the electrical components but with which the other electrical component is matable, the contact element, nevertheless, having a long useful life despite having to undergo numerous mating and unmating cycles of said other electrical component.

The first and second contact sections are preferably arranged to be mechanically isolated from each other so that the resistance to mating deflection of the second contact section does not interfere with that of the first contact section.

The present invention also concerns an interposer contact module in which the contact element can be mounted so as to achieve such mechanical isolation, and a land grid contact array in which the contact element is used.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which; Figure 1 is a plan view of an electrical contact element according to the embodiment of the present invention; Figure 2 is isometric view of the contact element of Figure 1; Figure 3 is an isometric view of a contact module for receiving contact elements according to Figures 1:: and 2; Figure 4 is a plan view of the contact module; Figure 5 is an elevational view of the contact module; Figure 6 is a fragmentary cross-sectional view of the contact module showing contact elements according to Figures 1 and 2 received in cavities in the module; Figure 7 is a similar view to that of Figure 6 but showing first and second electrical components in the form of printed wiring boards positioned for mating with the contact module; Figure 8 is a view taken on the lines 8-8 of Figure 7; Figure 9 is a similar view to that of Figure 7 but showing the electrical components mated with the contact module; Figure 10 is exploded isometric view showing an interposer nest containing a plurality of the contact modules, the electrical components, and a pair of electrical connector modules;; Figure 11 is a fragmentary, exploded, isometric view of part of the interposer nest; Figure 12 is a cross-sectional view showing the interposer nest positioned for mounting to the second electrical component and to a bolster plate.

Figure 13 is an isometric view of a framework of a cable side connector for use with the interposer nest and the electrical components; Figure 14 is a cross-sectional view of the cable side connector showing only an interlocking assembly of the framework; Figure 15 is a similar view to that of Figure 14 but showing the cable side connector mated with an interposer nest and the first and second electrical components, and with a device side connector; Figures 16 and 17 are fragmentary sectional views illustrating parts of the device side connector and manner in which they are mounted to an electronic device; Figure 18 is an enlarged sectional view showing an electrical connector module of the cable side connector mated with the first electrical component which is, in turn, mated with the interposer nest which is mated with the second electrical component;; Figure 19 is a cross-sectional view of the framework of the cable side connector showing some details of the interlocking assembly; Figure 20 is a view taken on the lines 20-20 of Figure 19; Figure 21 is a view taken on the lines 21-21 of Figure 19; Figure 22 is a cross-sectional view of the device side connector; Figure 23 is a view taken on the lines 23-23 of Figure 22; Figure 24 is a view taken on the lines 24-24 of Figure 22; Figure 25 is an exploded isometric view of an interposer nest according to another embodiment of the invention disposed between two electrical components in the form of printed wiring boards; Figure 26 is an isometric view of the interposer nest of Figure 25;; Figure 27 is an enlarged isometric view of an electrical contact module of the interposer nest of Figures 25 and 26 with electrical contact elements according to another embodiment of the invention received in the module; Figure 28 is a similar view to that of Figure 27, but showing one of the contact elements exploded from the module; Figure 29 is a plan view of one of the electrical contact elements of the module Figures 27 and 28; Figure 30 is an end view of the contact element shown in Figure 29; Figure 31 is a cross-sectional view of the module Figures 27 and 28 with a contact element thereof removed; Figure 32 is a view taken on the lines 32-32 of Figure 27; and Figure 33 is an end view of a part of the module shown in Figure 31.

As shown in Figures 1 and 2, an electrical contact element 300, according to an embodiment of the invention, comprises a first contact section 301 for electrically interfacing with a conductor such as, an electrically conductive contact pad, on a first electrical component. As used herein, the term "electrical component1, includes any device adapted to receive or transmit electrical signals. The contact element 300 also comprises a second contact section 302 for electrically interfacing with a conductor such as an electrically conductive contact pad, on a second electrical component. The interfacing contact sections 301 and 302 are disposed in opposed relationship relative to one another for deflection towards one another, as explained in detail below.

The contact sections may vary widely in shape and size, depending primarily upon the size and shape of the conductors on the associated electrical components.

Each electrical component may be a substantially flat printed wiring board, the interfacing conductor being a contact pad on a surface of the wiring board. It is preferred that the first interfacing contact section 301 comprises a nose 303 having an arcuate contact surface 304 for contact with a pad on a first printed wiring board. Likewise, the second interfacing contact section 302 preferably comprises a nose 305 having an arcuate contact surface 306 for contact with a pad on a second printed wiring board . As used herein, the term "printed wiring board" (PWB) means an electrical component that includes a substantially flat portion adapted to bus data signals.Thus, the terms "printed wiring board" or "PWB" as used herein are intended to include such electronic components as printed circuit boards (PCBs) or any other electrical component adapted to bus electrical signals from one location to another.

The contact element 300 comprises means for electrically connecting said first and second interfacing contact sections 301 and 302 and spring bias means for providing a first amount of spring bias to said first contact section 301 and a second amount of spring bias to said second contact section 302. The spring bias means provides "mating resistance" to the contact section. As used herein, "mating resistance" means the resistance to deflection of an interfacing contact section that occurs during mating of the contact element with its associated electrical component. The resistance to mating deflection generally corresponds to the contact force of the interfacing contact section.The level of the required contact force is an important variable in the effectiveness of electrical contact and will generally vary depending upon the material of which the interfacing conductor on the electrical component is made.

Where the contact sections 301 and 302 opposed, as shown, their deflection will be generally towards one another. It has been found that it is highly desirable that, in certain cases, the amount of resistance to mating deflection of the first contact section 301 should be independent of the amount of resistance to mating deflection of the second contact section 302. In this way, the spring bias means can provide a first resistance to mating which is adapted to maximize the cycle-life of the contact. For example, the first contact section 301 may be adapted electrically to interface with a separable or mating interface of a first electrical component under the relatively low contact force that is normal between conductive surfaces which are gold-plated or are plated with AMP DURAGOLD plating (described in US-A-5,129,143).Highly effective contact can thus be made with such conductors at reduced contact forces as low as 80 grams. The second contact section 302 is, however, adapted electrically to interface with a second electrical component, which involves relatively high contact force conductive interfaces between surfaces such as tin or tin-lead plated interfaces. Effective contact with such interfaces generally requires a minimum contact force of about 100 grams and preferably about 200 grams in a connector arrangement which is fixed together when assembled rather than being matable and unmatable during in-service use.

According to one embodiment the mating resistance spring bias means comprise a first spring portion 307 connected to the first contact section 301 and a second spring portion 308 connected to the second contact section 302. The first and second spring portions 307 and 308 are also connected to one or more bights 309.

In contacts elements in which the spring portions and the bights are of electrically conductive material, as is preferred, the mating resistance spring bias 307, 308 also comprise means, the bights 309 in the present example for electrically connecting the first and second contact sections.

The first spring portion 307 comprises an inner arm 310 connected to a first end of a bight 309 and an outer arm 311 connected to the contact section 301. The inner spring arm 310 and the outer spring arm 311 are connected by first resilient connecting means in the form of a spring bight means 312 for resiliently resisting deflection of the outer arm 311 towards the inner arm 310, as normally occurs during mating of the contact element 300 with an electrical component. As shown, the bight 312 comprises a generally U-shaped segment in which the radius of the arcuate portion of the segment lies at least in part between the inner arm 310 and the outer arm 311. In this way, the outer arm 311 is generally opposed to the inner arm and moves toward the inner arm during mating deflection.

The second spring portion 308 similarly comprises an inner arm 313 connected to the bight 309 and an outer arm 314 connected to the second contact section 302.

The inner arm 313 and the outer arm 314 are connected by second resilient connection means in the form of a spring bight 315 for resiliently resisting deflection of the outer arm 314 towards the inner arm 313, as normally occurs during mating of the contact element 300 with an electrical component. As shown, the bight 315 also, comprises a generally U-shaped segment in which the radius of the arcuate portion of the segment lies at least in part between the inner arm 313 and the outer arm 314. In this way, the outer arm 314 is generally opposed to the inner arm and moves toward the inner arm during mating deflection.

The mating resistance spring bias means comprises the first bight 312 which provides a first amount of resilient resistance to deflection of the outer arm 311 towards the inner arm 310 and the second bight 315 which provides a second amount of resilient resistance to deflection of the outer arm 314 towards the inner arm 313. To this end the arcuate portion of the U-shaped segment of the bight 315 is thicker in at least one dimension than the arcuate portion of the U-shaped segment of the bight 312. Thus the bight 315 has a width in the dimension approximately normal to the direction of deflection, which is greater than the width of the same dimension of the bight 312.

As shown in Figure 2 and 8, the contact element 300 is substantially flat and uniplanar having been stamped from a single sheet of metal. The motion of the interfacing contact sections 301 and 302 being substantially within the plane of the contact element 300 during mating deflection.

The interfacing contact sections 301 and 302 are each eventually resiliently deflected upon completion of the mating operation so as to provide the required contact pressures. In order to facilitate the provision of a contact element having at least two levels of contact pressure, it has been found that means should be provided for decoupling the resilient response of the first contact section 301 from the resilient response of the second contact section 302. That is, to say it is desirable to provide means for allowing the spring bight 315 to act independently of the spring bight 312. If such decoupling means were not provided, the spring bight having the lower resilient resistance to mating deflection would tend to control or limit the resilient resistance potentially provided by the other spring bight.

With reference to Figures 1 and 7, such decoupling means comprises a support means for supporting at least the second contact section 302 against non-resilient translational movement. The support means comprises in the present example a support arm 317 connected between the bights 309 and extending generally in a direction normal to the direction of deflection of contact sections 301 and 302. As described more fully below, the support arm 317 is adapted mechanically to engage with the interior edge walls of a cavity in an insulative housing for operatively holding the contact element 300 during the mating process. In this way, the arm 317 is capable of supporting at least the second contact section 302 against non-resilient translational movement.

As mentioned above, high cycle-life contact elements most desirable in certain applications. As used herein, "cycle" means the cycle of operation experienced by an interfacing contact section and its associated spring bight during mating and unmating.

Accordingly, "cycle-life" means the number of cycles, on average, that a contact element, or a portion of a contact element, is capable of withstanding without failure. The contact element 300 is adapted to have a cycle-life of at least about 15,000 cycles and up to about 50,000 cycles.

The contact element 300 includes stabilizing means for stabilizing it against destructive torsion during in-service use. Such stabilizing means contributes to the high cycle-life of contact element 300. The stabilizing means comprises elongate stabilizer arms 318 and 319 which extend from the ends of the support arm 317 in a direction substantially parallel to the direction of contact section deflection.

The contact element 300 is especially for use in an interposed type connector arrangement which provides a contact system having a large plurality of contact elements disposed for operative mating with contact pads on electrical components. The contact element 300 is intended to be adaptable for use with a wide variety of such interposer connector arrangements.

As shown in Figures 3 to 5 and interposer connector arrangement comprises a contact module 200 having an insulative housing 320. The housing 320 has a first interface surface 321 and a second interface surface 322. The interface surfaces 321 and 322 are substantially flat surfaces which are substantially parallel to one another. A plurality of cavities 323 for containing respective contact elements 300 are formed in the housing 320. For the purposes of illustration, the contact sections 301 and 302 of a single contact element 300 are shown extending from openings in the housing in Figures 3 and 5.

As seen in Figure 6, each cavity 323 defines a first opening 324 in the surface 321. Prior to mating the contact module with an electrical component the contact surface 304 of the contact section 301 extends through and beyond the opening 324 and is maintained in an elevated position relative to first interface surface 321 of housing 320. Likewise, each cavity 323 also defines a second, and longer, opening 325 in the second interface surface 322, and the contact surface 306 of the second contact section 302 extends through and beyond the opening 325 and is maintained in an elevated position relative to the second interface surface 322 of housing 320. The housing 320 comprises a plurality of such cavities 323, and preferably two rows 326 of closely spaced parallel cavities, as shown in Figures 3 and 4.

One method of assembling the contact module 200 will now be described. Housing 320 is for example molded from a fluid plastic resin material. Each contact element 300 is inserted into its cavity 323 through the opening 325 thereof. Each cavity 323 is defined by side walls 327 and end walls 328 and 329, as shown in Figures 6 to 8. Each end wall 328 and 329 is formed with a shoulder 330 adapted to allow the passage of the first contact section 301 to, and through, the opening 324 in surface 321. However, the shoulders 330 are adapted mechanically to interfere with translational movement of the support means 317 towards opening 324 and thus act as precisely located stops.

The contact elements 300 are preferably integrally formed, by stamping for example, from a sheet of conductive material. It is preferred that the stamping process provides the contact element or series of contact elements with a frangible section or snap bar (not shown) attached to the ends of stabilizer arms 318 and 319, which aids in the insertion of the contact element into its cavity 323. After the contact element 300 has been inserted into its cavity 323, the snap bars are removed as is well known in the art. A portion of the edge of each side wall 327, which comprises the surface 322 is formed with a ridge 331 of plastic material (Figure 6). Since the ridge 331 is located on the sidewall 327, it does not interfere with insertion of the contact element 300 into its cavity 323.After the snap bar has been removed, however, the ridge 331 is flattened, preferably by heat staking the plastic material thereof to the level of the surface 322, to define an embossment 331A (Figure 7) traversing the entrance to the cavity 323 and providing a means for preventing inadvertent dislocation of the contact element from the cavity 323 outwardly from opening 325.

The mating of contact elements 300 with first and second electrical components 30 and 210 will now be described with reference to Figures 7 to 9. Figures 7 and 8 illustrate the pre-mating position of the electrical components and the contact elements, and Figure 9 illustrates both components fully mated with the contact module 200'. The mating of the first and second components 30 and 210 may proceed in any desired order. That is, either the component 30 or the component 210 may be first mated with the contact module 200' followed by the mating of the remaining component, or the mating of each component may proceed substantially simultaneously. However, the preferred mating process will now be described.

In the preferred mating process, the electrical component, 210, which is a printed wiring board (PWB), as shown, is first juxtaposed with the connector module housing 320 such that the interface surface 322 thereof is substantially parallel to the surface 212 of the component 210 and such that raised contact pads 205 thereof are in operative alignment with the second interfacing contact sections 302 of the contact elements 300. The electrical component 210 is then brought into mated and fastened relationship with the connector module housing 320. That is, to say the raised pads 205 of the component 210 are brought into intimate contact with the interface surface 322 of connector module housing 320.

The second contact section 302 of each contact element 300 engages a respective pad 205 upon the assembly of an interposer nest 200 (Figures 10 to 12) containing an array of connector modules 200' to a bolster plate 190 on which is disposed the electrical component 210 as best seen in Figure 13. The engagement of the contact section 302 with the pad 205 produces a force on the contact element which urges translation thereof towards the opening 324 in the opposite interface surface 321. This initial translation continues until the support arm 317 of the contact element 300 mechanically interferes with the shoulders 330, thus preventing further translation of the contact element 300.The translational interference between the shoulders 330 and the support arm 317 also serves to decouple the spring bights 307 and 308 such that spring bight 307 can effectively operate at its lower contact pressure despite the presence of a higher contact pressure at pad 205.

The dimensions of contact element 300 and of the contact module cavity 323 are further selected such that the surface 322 of the contact module 200' is not fully mated with surface 212 of PWB component 210 when the support arm 317 is in intimate contact with the shoulders 330. As the mating operation is completed and the surface 322 is fully mated to the surface 212, as shown in Figure 9, the second contact section 302 is deflected so as to relieve the continued stress caused by the mating operation. The spring bight 308 resiliently resists this deflection, thereby creating a normal contact force at the pad 205.

The second contact section 302 provides a relatively high contact force, such as would be required for contact pads 205 formed of tin or tin-lead, where a contact force of about 200 gm. may be desirable.

The electrical component 210 is preferably substantially permanently affixed and mated to the contact module housing 320, although such permanence may not necessarily be required. In contrast, the electrical component 30 is adapted to be repeatedly mated with, and unmated from, the nest 200. The electrical component 30 is mated with the nest 200 substantially as described above with reference to the component 210, excepting that the entirety of the stress produced by the mating of the component 30 is relieved by the spring bight 307 as the first interface contact section 301 is deflected from its unloaded position. As a result, a contact pressure corresponding to the resistance to deflection of the spring bight 307 is produced at the pad 160.The pads 160 of component 30 are easily engageable and disengageable from first contact sections 301 for many mating cycles, and are preferably gold-plated so that only a reduced normal contact force of about 80 gms is needed. Optionally, first contact section 301 is be preloaded raising by the spring arm 311 against a surface 332 of the housing 320 upon assembly of contact elements 300 in the contact module 200', or upon mounting the loaded module housing 320 to the component 210.

As shown in Figure 11, the interposer nest 200 may be of metal and contain an array of module-receiving cavities 340 extending from a first surface 342 to a second surface 344, with first surface 342 associated with the component 30 and second surface 344 associated with the component 210. Each cavity 340 is shaped asymmetrically to complement the asymmetric shape of a respective contact module housing 320 permitting only one orientation of the housing 320 and thereby being polarized. Each contact module housing 320 preferably includes lip sections 346 and 348 of common thickness, which abut adjacent portions of the second surface 344 of the interposer nest 200 upon the insertion of the contact module 200' into a respective cavity 340.

Abutment of lip sections 346 and 348 against the second surface 344 enables contact module insertion to a precisely controlled depth. Preferably the dimensions of the module housings 320 are incrementally larger than the dimensions of the module-receiving cavities 340 so that the modules 200' are interference fitted into cavities 340.

As shown in Figure 12, the interposer nest 200 includes mounting holes 350 which are alignable with corresponding mounting holes 352 in the component 210 and mounting holes 354 in the bolster plate 190 thereunder, for the receipt of fasteners (not shown) for assembling the interposer nest 200 to a framework of an electronic device, in biased engagement against component 210 mounted to the bolster plate 190, generating the requisite normal contact force between the second contact sections 302 of the contact elements 300 of the contact modules 200 in the interposer nest 200. The lip sections 346 and 348 of the contact modules 200' are disposed between second surface 344 of interposer nest 200 and component 210.Spacer elements 360 surrounding the mounting holes 350 of the interposer nest 200 spacing the nest 200 with respect to the component 210 upon assembly, to relieve stress on the lip sections 346 and 348 of contact module housings 320.

The provision of the lip sections 346 and 348 permits removal of a contact module 200' for repair or replacement during servicing. A combination between wiring board components and interposer means constitutes what is known in the art as a land grid contact array.

By virtue primarily of the effect of the support arm 317 in decoupling lower part from upper part of the contact element 300, the latter has a high cycle-life.

To some extent, the stabilizer arms 318 and 319 in interference fit with the end walls 328 and 329 serve to stabilize and rigidify the contact element during the mating process. The contact element 300 thus exhibits significant resistance to degradation and failure even after numerous mating and unmating cycles. While each contact element 300 is stamped from a sheet of conductive material such as beryllium copper alloy of selected thickness, the sheet may be coined to define a lesser stock thickness at the first contact section 301, including the inner and outer arms 310 and 311 and the bight 312, for example 0.01016 cm, and a greater stock thickness at the second contact section 302; including the inner and outer arms 313 and 314 and the bight 315 therebetween, for example 0.01524 cm, and preferably also at the support and stabilizer arms 317, 318 and 319.

The contact modules 200' and their contact elements 300 are adaptable for use in a wide variety of connector systems and for a wide variety of applications. An example of such use in a particular connector system will now be described with reference to Figures 10 to 24.

Figures 13 to 15 show a cable side connector 10 having a support structure 70. The cable side connector 10 comprises an insulative housing 20 (not shown in Figure 13) encasing the component 30 which is a printed wiring board (which term includes printed circuit boards) adapted to receive connector modules 80 for communicating data from an outside source to the component 30 and being terminated to discrete coaxial leads 230 of a jacketed cable 225 extending through a cable exit 75.

The component has a plurality of plated-throughholes 40 which mate as shown in Figure 14 with contact members of the connector modules 80 and are connected to respective pads 160 as shown in Figure 18. Actuating means 50 is interfaceable through the component 30 by way of an opening 60 therethrough to secure the connector 10 to the bolster plate 190 (Figure 15). The component opening 60 preferably lies substantially in the center of the component 30. The actuating means 50 is manually actuable to press the component 30 against the nest 200 such that an array of contact pads of the component 30 makes effective electrical contact with the contact elements 300 of the nest 200.

The connector 10 is both matable with, and unmatable from the nest 200 as mentioned above. The component 210 could, for example, be mated with an analytical or diagnostic-type medical electronic device 350A (Figure 22) such as ultrasound equipment, X-ray equipment, or other medical equipment which processes digital data signals from an outside source to perform a diagnostic function. The outside source could be, for example, an ultrasound sensor, or other type of electrical component which transduces physical parameters to electrical signals which can then be processed by a computer or microprocessor contained in medical 350A device.

A first side 90 the "contact" side of the component 30 and comprises a plurality of contact surfaces outwardly exposed to make electrical contact with the contacts elements 300 of the nest 200. A second side 100 of the component is arranged to be attached to a securing ledge 110 on housing 20. The periphery of second side 100 abuts, and is fastened to the securing ledge 110 after the connector modules 80 have been plugged into the through plated-through-holes 40, so as to hold the component 30 in position in the connector 10.

The actuating means 50 comprises a securing barrel 120 that extends through a tubular housing 125 of support structure 70 and is rotationally mated through the opening 60 in the component 30, for securing and interfacing said first side 90 to the interposer nest 200. Interlocking means 130 attached to the securing barrel 120 is provided for clinching the securing barrel 120 to a cooperable locking surface 240' of a spring loaded device 240 depending from the bolster plate 190 as shown in Figure 15. By cinching the interlocking means 130 to the cooperable surface 240', the securing barrel 120 exerts sufficient force to hold the contact surfaces on the first side 90 of component 30 to the corresponding contacts 300 of the interposer nest 200 (Figure 18).

Figure 15 shown the connector 10 with the component 30 secured thereto mated with the interposer nest 200 which is in turn mated with the component 210 on the plate 190. As best seen in Figure 18, on the first side 90 of the component 30, a plurality of the pads 160 are in electrical communication with the plate-through-holes 40. The pads 160 make electrical contact with corresponding contact elements 300, in the manner described above, so that data signals can be bussed through the connector modules 80 to the electronic device side component 210 via the pads 205. The component 210 and the bolster plate 190 are secured to a device side connector 140 by mounting screws 180. The component 210 may be, for example, a motherboard, which is adapted to receive and process the data bussed through the connector modules 80 to the nest 200 and the component 210.The nest 200 may be assembled to component 30 of the connector 10, or maintained in registry with the component 210 by alignment pins but being otherwise unsecured thereto or to the component 30. In this situation, pads 160 would make electrical contact with the component 210 through reciprocal contact surfaces on the component 210.

The bolster plate 190 provides a sturdy surface for the mounting screws 180 so that the connector 10 is held in tight engagement with component 210 of the device side connector 140 comprising the nest 200 and the printed wiring board component 210. The screws 180 extend through the bolster plate 190 from a chassis 360A of the electronic device 350A, through an aperture in an inner standoff bezel 210A extending along the inner surface of the chassis 360A with an outer bezel 200A secured to the outward surface of the chassis 360A (Figure 16). Inner and outer bezels 210A and 200A together form a frame into, and through, which the cable side connector 10 can be guided to make contact with the nest 200 and component 210 of the device side connector 140.The bezel 200A is secured by screws 185 extending outwardly through the chassis 360A and threaded into corresponding apertures 187 in the outer bezel 200A as shown in Figure 16. The screws 180 are pressed into profiled holes 182 of chassis 360A as shown in Figure 17.

The connector 10 further includes a cable exit holder section 74 (Figure 13) integrally formed with the housing 70 (Figure 14). A clamp member 72 is fastenable to the holder section 74 to define the cable exit 75 for clamping a cable feed tube 220 which is adapted to receive the jacketed cable 225 (Figures 14 and 15) containing a substantial number of the discrete coaxial leads 230, when the tube 220 is clamped to an outer jacket 227 of cable 225. The leads 230 may be of very small gauge having center conductors of 0.0079756 cm (AWG 40). The feed tube 220 provides strain relief for the electrical terminations within the connector 10.

The leads 230 are terminated to respective signal and ground terminals in each of the connector modules 80 so that electrical signals can be bussed from said outside source through the connector modules 80 to the component 210.

The connector 10 is particularly useful in microcoax cable applications where many such modular connectors with associated microcoaxial leads are used.

The cable feed tube 220 maintains the leads 230 in a neat jacketed bundle so that the connector 10 can be efficiently handled and remain easily accessible for service. The bundling of the leads 230 through the cable feed tube 220 also allows the connector 10 to be easily mated and unmated by the user of device side connector 140 without interference by the multiplicity leads 230.

As shown in Figures 13, 14 and 22, the securing barrel 120 traverses the opening 60 in the component 30, and corresponding openings provided in interposer nest 200, the component 210, and the bolster plate 190. The securing barrel 120 may be a solid shaft made of a rigid material such as stainless steel. The interlocking means 130 is preferably integrally formed on the distal end of the barrel 120 from the same material as the barrel 120, and cooperates with the surface 240' to secure the connector 10 to the device side connector 140. The plate providing the cooperating surface 240' may be cast in a single piece with the bolster plate 190 of device side connector 140, or alternatively said plate may be secured by screws or other fastening means.

When it is desired to mate cable side connector 10 with the device side connector 140 and to secure the component 30 to the interposer nest 200, the cable side connector 10 is placed in initial operative association with the device side connector 140 by passing the distal end of barrel 120 through the aligned openings in the nest 200, the component 210, and the bolster plate 190.

The barrel 120 and interlocking means 130 are then preferably rotated by manual activation of a handle knob 245 on an engaging surface 250 (Figure 19) integrally formed with the proximal end of the barrel 120 to cause the interlocking means 130 to clinch the barrel 120 to the cooperating surface 240, thereby securing the cable side connector 10 to the device side connector 140.

According to an embodiment, when the engaging surface 250 is rotated by means of the knob 245, a set of spring members such as Belleville washers 260 within a cylindrical bearing cover 275 operate on a bearing carrier 270 to transmit the force generated by the camming of the interlocking means 130 downward on the cooperating surface 240 and onto the support structure 70 of the connector 10, thereby forcing first side 90 of component 30 onto the nest 200 with sufficient force to bring pads 160 into electrical engagement with the contact elements 300 in the nest 200. The force is gradually applied through the barrel 120 and the bearing carrier 270 as the interlocking means 130 bears against the cooperating surface 240 during rotation through a quarter turn of the knob 245, whereafter the interlocking means 130 seats in a recess, so that mating is completed.The Belleville washers 260 also provide uniform achievement of the desired force to be applied to the nest 200 thereby compensating for varying thickness of the nest 200, the bolster plate 190, and the components 210 and 30. Alternatively, the cooperating the surface 240' can be fitted with compression springs, as described above with reference to the spring loaded device 240, which would provide the uniform force application onto the nest 200 by the barrel 120.

Figure 18 illustrates the engagement of the pads 160 with the nest 200. The connector modules 80 are electrically connected to the plated-through-holes 40 of the components 30 by electrical terminals having contact pins 280. The pins 280 make electrically conductive contact with the tin-plated surfaces of the platedthrough-holes 40 the pins 280 may be according to US-A4,186,982. Methods of manufacturing connector modules which can be used in the embodiments described herein are described in AMP Incorporated Technical Paper by R.

Rothenberger and R.S. Mroczkowski, entitled "High Density Zero Insertion Force Microcoaxial Cable Interconnection Technology," (1992).

As shown in Figure 18 the pins 280 are secured in, and are conductively engaged with the plating material of the plated-through-holes 40 which are in electrical communication with pads 160 so that sufficient electrical connections are made from the outside source via the coaxial leads 230 through the connector modules 80 to the component 30. When the component 30 is secured against interposer nest 200, the pads 160 are further placed in electrical communication with the interposer contact elements 300, as described above.

The interposer contact elements 300 are also interfaced at the lower surface of the nest 200 to the pads 205 on the component 210 as described above. Circuits on the printed wiring board components 210 enable data to be bussed to of the component 210 which contain electronic elements for processing the data for analytical or diagnostic purposes, for example.

The interposer contact elements 300 which are interfaced with the pads 160 on the component 30 and the pads 205 on component 210 must make sufficient electrical contact therewith to ensure that data can be bussed through the connectors 10 and 140 with high reliability. Thus, as described above with reference to Figures 6 to 9, the correct amount of contact force is ensured by the construction of the contact elements 300 and the cavities in which they are accommodated.

However, the force to be applied at the interface between each pad 160 and the associated interposer contact element 300 by securing the barrel 120 and bearing carrier 270 will be gauged for the particular interposer contacts 300 used.

Reference will now be made to Figures 19 to 24. In a further embodiment the interlocking means comprises a key element 130' which is received through a corresponding key-shaped hole 155 (Figures 23 and 24) in the cooperating surface 240' engage a complementary cooperating surface in the device side connector 140.

The interlocking means 130 could otherwise comprise a combination of the key element 130' and a latching pin which would further hold the barrel 120 to the cooperating surface 240' The connector 10 is secured to the connector 140 and the electrical component 30 is secured to the nest 200 as the securing barrel 120 is rotated by manual activation of the knob 245 as in the other embodiments.

The interlocking key element 130' bears against the surface 240' during said rotation, which defines a complementary key channel so that the interlocking key is clinched to the key channel. This in turn, through thrust-bearings, that is the Bellville washers 260, presses against the bearing carrier 270 mounted atop support the structure 70 carrying the component 30 so that the latter is securely pressed against the interposer nest 200, with the bearing carrier 270 and the bearing cover 275 which is integrally fastened to the support structure 70. Full locking is indicated to the operator by means of a ball plunger detent (not shown) housed in an embossment 127 of the bearing carrier 270, the detent entering a recess when the barrel 120 has been rotated through the selected angular distance, such as a quarter turn.

As shown in (Figures 22 to 24), the surface is a hub 240A having key camming surface 320A that is adapted cooperatively to engage with the key element 130'. When the barrel 120 forces key element against the key camming surface 320A, the barrel 120 then rotates the key element (130') along the camming surface 320A to pull the bearing carrier 270 and the connector 10 down, thereby imparting sufficient force to bring the contact pads 160 of the component 30 firmly against the interposer contact elements 300. The bearing carrier arrangement may exert between 9.08 kg (for a low contact count) and 90.8 kg (for a high contact count) of force to accomplish this result. In an arrangement having, for example, six hundred and twelve pairs of contact surfaces to be interconnected, the bearing carrier experts 68.1 kg of force to bring the interposer contacts elements 300 and pads 160 together.

Figure 22 shows the component 210 on the device side connector 140 interfaced with a card edge connector 340A of the electronic device. The card edge connector 340A is further interfaced with a motherboard 351A which is part of the electronic device 350A which receives the data signals bussed through the connector 10 so that the data signals can be utilized by the electronic device 350A. As shown in Figures 16 and 17 the chassis 360A of the electronic device includes a cut-out aperture 370A, so that the connector 10 can be received into the chassis 360A to mate with device side connector 140 of the electronic device 350A.

Figure 23 is a plan view of the interposer nest 200 mounted in device side connector 140. Preferably, pins 330A extending upwardly therethrough, as shown in Figure 22, serve so as to align the component 30, the interposer nest 200 and the component 210 precisely to align their respective contact arrays when the pins 330A are received in complementary alignment openings 332A of the connector 10 (Figure 21). In Figure 24, the hub 240A interfaces with the key element 130' in the complementary key camming surface 320A so that the key camming surface holds the key in place as the keying element is rotated on the key camming surface 320A. A pair of compression springs may be provided to the hub 240A to counterbalance and control the force supplied by the bearing carrier 270 through the support structure 70 to the electrical component 30, as mentioned above.

When 68.1 kg of force is to be applied by bearing carrier 270 to the component 30 to secure the pads 160 to the nest 200, the compression springs should be compressed when more than 68.1 kg of force is applied by the bearing carrier 270, being thereby contracted to all the hub 240A to move upwardly towards the bolster plate 190. This in turn ensures that a force of 68.1 kg is applied irrespective of variations in thickness of component 30, the component 210, the interposer nest 200 and the bolster plate 190. Thus, the compression springs provide control means for ensuring that the wiring boards that is to say the components 30 and 210, and the nest 200 are compressed by the desired force applied to them by the actuating means 50 and the bolster plate 190 as the key element 130' interfaces with the camming surface 320A.

As will be apparent from Figures 14, 22 and 24 the keying element will traverse through the opening 155 until the keying element is first below the uppermost extent of the downwardly facing camming surface 320A.

The barrel 120 is then rotated by manual rotation of the knob 245 so that keying element 130' traverses along, and bears against the camming surface 320A to the lowest point thereof, thereby causing the washers 260 to urge support structure 70 downward and forcing the component 30 onto interposer nest 200. Thus, the pads 160 on the component 30 are brought firmly and assuredly into flush contact with interposer contact elements 300 so that adequate electrical contact is maintained for data signals to be reliable bussed into the electronic device 350A.

The land grid contact array described above ensures reliable contact surface interfaces so that the connector system described above effectively guarantees that electrical signals are bussed through the system with integrity.

A further embodiment of a land grid contact array will now be described with reference to Figures 25 to 33. As shown in Figure 25 an interposer nest 410 is disposed between electrical components 411 such as compliant printed wiring boards or similar circuitry having pads for making electrical contact. The components 411 and the interposer nest 410 are fixed so as to be registered with one another so that the pads on the electrical components 411 are positioned to mate with electrical contact elements 413 on the interposer nest 410. The interposer nest 410 can mate and unmate with the electrical components 411 through some hundreds of cycles as described below, during the useful life of its contact elements 413.

The interposer nest 410 comprises an array of contact modules 412 each having a plurality of electrical contact elements 413 inserted therein. The nest 410 of contact modules 412 comprises a support 414 (Figure 26) and is disposed between the compliant electrical components 411 as mentioned above. Each contact module 412 is made an insulative material and has a top face 415, a bottom face 416, a first side 417 and an opposite second side 418 (Figures 27 and 31).

The electrical contact elements 413 are inserted into the contact module 412 preferably from both sides 17 and 18 thereof for economy of space and to provide a maximum number of electrical contact elements 413 for each contact module 412. The electrical contact elements 413 may be inserted on staggered 0.0508 cm centerlines. The insertion and retention of the electrical contact elements 413 in the contact module 412 will now be described. A portion of each electrical contact element 413 extends outwardly from the top face 415 and the bottom face 416 of the contact module 412 to make electrical connection with the pads of the electrical components 411.

The electrical contact elements 413 are epsilonshaped elements each having a rigid support arm in the form of a center leg 420. A contact section in the form of a first spring beam 421 and a contact section in the form of a second spring beam 422 are each connected to the center leg 420. Further, each beam 421 and 422 has a respective end 423, 424 distal from the center leg 420 as best seen in Figure 29. The respective ends portions 423, and 424 of the beams 421 and 422 have outwardly bowed arcuate contact surfaces 425 and 426 respectively, each for making electrical component contact with a pad of a respective electrical component 411. The center leg 420 has an end portion 427 distal from its connection with the beams 421 and 422, the end portion 427 is tapered outwardly and is thus narrower than the remainder of the leg 420.

The epsilon-shaped contact elements 413 are provided, for rapid and economical production, by stamping out from a sheet of electrically conductive material having a uniform thickness of approximately 0.01524 cm. The material, which is sufficiently resistant to plastic deformation to enable each contact element 413 to withstand some hundreds of mating and unmating cycles, is preferably spring-tempered beryllium copper.

The material of each electrical contact element 413 provides resilience to the beams 421 and 422 so that when the interposer nest 410 is mated with the electrical components 411, the respective beams 421 and 422 are urged towards the center leg 420. The end portions 423 and 424 of each beam are thereby each displaced by approximately 0.0508 cm. This displacement provides a wiping motion of the respective end portions 423 and 424 of the beams 421 and 422 across the respective pads of the electrical components 411. A minimum of 0.254 cm of wiping motion is produced such that an excellent electrical connection is provided between the contact element 413 and said pads. The arcuate contact surfaces 425 and 426 of the respective beams 421 and 422 may be coated with or plated with, a corrosion resistant electrically conductive material.

It is preferred that the end portion 423 of the first beam 421 is gold preferred that the end portion 423 of the first beam 421 is gold plated, the end portion 424 of the second beam 422 being plated with a tin alloy such as a tin-lead alloy.

The first beam 421 having a width of approximately 0.4572 cm which provides a normal contact force of approximately 100 g. This contact force is typical of that used with gold plated contacts and provides a good electrical connection between the beam 421 and a respective pad of the component 411. The second beam 422 has a width of approximately 0.06096 cm which provides a normal contact force of 200 g. This contact force is typical of that used with tin-lead alloy plated contacts and provides a good electrical connection between the beam 422 and a respective pad of the electrical component 411.

As shown in Figures 31 and 32, each contact module 412 has a plurality of spaced-apart retention cavities 430 formed on both sides 417 and 418 of the module 412.

Each of electrical contact elements 13 is individually inserted into a respective retention cavity 430. Each respective retention cavity 430 has a portion which communicates with the top face 415 of the contact module 412 and with the bottom face 416 of the contact module 412 such that when a electrical contact element 413 is received in its respective retention cavity 430, the arcuate contact surface 425 of the first beam 421 extends outwardly above the top face 415 of the contact module 412 and the arcuate contact surface 426 of the second beam 422 extends outwardly below the bottom face 416 of the contact module 412. Further, each retention cavity 430 has a center portion 431 in which the center leg 420 of the respective electrical contact element 413, is received.The tapered end portion 427 of the center leg 420 of the electrical contact element 413 is initially received in the center portion 431 to guide the insertion of the electrical contact element 13 into its cavity 430. The center leg 420 of the electrical contact element 13 is retained in the center portion 431 of the retention cavity 430 by an interference fit. The interference fit restricts lateral and vertical movement of the beams 421 and 422 during mating and unmating of the nest 410 with the electrical components 411. The interference fit and the configuration of the retention cavity 430 also accurately position each electrical contact element 413 within the contact module 412.As best seen in Figure 33 the center portion 431 of the retention cavity 430 is a profiled slot having diametrically opposed portions 432 in which the center leg 420 of the electrical contact element 413 is received. The portions 432 have a width which is less than that of the remainder of the center portion 431 of the retention cavity 430. The width of each portion 432 is approximately the same as the thickness of an electrical contact element 413.

The epsilon shape of the electrical contact element 413, the configuration of the retention cavities 430 and the interference fit of the center leg 420 in the center portion 431 of the retention cavity 430 are compatible with the automatic insertion of the electrical contact elements 413 into the contact module 412. In this manner, the interposer nest 410 can be rapidly and inexpensively assembled.

Since the center leg 420 is firmly fixed in the center portion 431 of the cavity 430, the center leg 420 serves to isolate the spring beams 421 and 422, so that the resilient response of beam 421 is decoupled from that of the beam 422, whereby the beam 421 having the lower resistance to mating deflection does not tend to control or limit the resilient resistance provided by the beam 422. The usefulness of this feature is discussed in detail above, in relation to the contact elements 300.

Claims (20)

1. An electrical contact element for mating with opposed electrical components, the contact element comprising a first resiliently deflectable contact section for mating with one of the electrical components, a second resiliently deflectable contact section for mating with the other electrical component, and a connecting portion connecting the deflectable contact sections, the first contact section being dimensioned so as to have a substantially lower resistance to mating deflection than the second contact section.

2. A contact element as claimed in claim 1, wherein the resistance to mating deflection of the first contact section is substantially half that of the second contact section.

3. A contact element as claimed in claim 1 or 2, wherein the first deflectable contact section is connected to the connecting portion by way of a first spring bight, the second contact section being connected to the connecting portion by way of a second spring bight, the first spring bight being at least in part of smaller cross-sectional area than the second spring bight.

4. A contact element as claimed in claim 1 or 2, wherein the first deflectable contact- section is at least in part of smaller cross-sectional area than the second deflectable contact section.

5. A contact element as claimed in any one of the preceding claims, wherein the connecting portion is in the form of a rigid support arm extending between the first and second deflectable contact sections for fixed engagement in a cavity in a housing for receiving the contact element, to decouple the mating resistance of the first deflectable contact section from that of the second deflectable contact section.

6. A contact element as claimed in claim 5, wherein the support arm is rectilinear and has at each end thereof a stabilizer arm extending at right angles to the support arm, the stabilizer arms projecting from the support arm on opposite sides of the second resilient contact section.

7. A contact element as claimed in claim 5, wherein the support arm is rectilinear and is directly connected to the first and second deflectable contact sections and extends between free ends thereof, the support arm having a chamfered tip disposed between said free ends and the contact element being substantially epsilon-shaped.

8. An interposer contact module comprising an insulative housing having a row of cavities each receiving a contact element as claimed in any one of claims 1 to 4, each first defectable contact section having a contact surface projecting from a top face of the housing and each second deflectable contact section having a contact surface projecting from a bottom face of the housing, the connecting portion of each contact element being in the form of a rigid support arm extending between the deflectable contact sections and being inteference fitted to the housing so as to decouple the mating resistance of the first deflectable contact section from that of the second deflectable contact section and to prevent translational movement of the contact element in the cavity.

9. A contact module as claimed in claim 8, wherein the support arm has at each end thereof a stabilizer arm projecting transversely of the support arm, each stabilizer arm having an edge engaged with a respective wall of the cavity.

10. A contact module as claimed in claim 8, wherein the support arm is received with an interference fit in a reduced cross-section portion of the cavity, which portion extends in a direction substantially parallel to the top and bottom faces of the housing and substantially centrally therebetween.

11. A contact element or contact module, as claimed in any one of the preceding claims, wherein said first deflectable contact section has a gold plated contact surface, said second deflectable contact section having a contact surface plated with tin or with an alloy thereof.

12. A contact element or a contact module as claimed in any one of the preceding claims, wherein said deflectable contact sections extend obliquely away from the connecting portion, the contact surface of each contact section being outwardly bowed and being located at a free end of the contact section.

13. A land grid contact array, comprising a first wiring board having conductive pads on an under side thereof, a second wiring board having contact pads on an upper side thereof, and an interposer nest having an array of contact elements as claimed in claim 1, the interposer nest being sandwiched between the first and second wiring boards with the first resiently deflectable contact section of each contact element in electrically conductive contact with a respective contact pad of the first wiring board and with the second deflectable contact section of each contact element in electrically conductive contact with a respective pad of the second wiring board, the first wiring board being matable with, and unmatable from, the interposer nest and the second wiring board being fixed to the interposer nest.

14. A grid array as claimed in claim 13, comprising a cable side electrical connector mounted on the upper side of the first wiring board and having electrical terminals electrically connected to respective contact pads of the first wiring board, the connector being provided with an interlocking device for clamping the wiring boards against the interposer nest so that the contact pads thereon make effective electrical contact with the deflectable contact sections of the contact elements.

15. A grid array as claimed in claim 14, wherein the cable side connector is received in a device side connector for connection to an electronic device, the device side connector being secured to the second wiring board.

16. A grid array as claimed in claim 14 or 15, wherein the interlocking device comprises a rotatable shaft extending through the wiring boards and the interposer nest and being connected to a clamping member beneath the second wiring board, the shaft having a key for co-operating with the clamping member to draw the wiring boards against the interposer nest upon rotation of the shaft.

17. A grid array as claimed in claim 16, wherein the shaft is provided with thrust bearings for pressing against a bearing carrier of the shaft, which is mounted on a support structure of the cable side connector, the thrust bearings serving to urge the second wiring board against the interposer nest.

18. An electrical contact element for mating with opposed electrical components, substantially as hereinbefore described with reference to the accompanying drawings.

19. An interposer contact module substantially as hereinbefore described with reference to the accompanying drawings.

20. A land grid contact array substantially as hereinbefore described with reference to the accompanying drawings.