WO1996000995A1

WO1996000995A1 - A conductive shield

Info

Publication number: WO1996000995A1
Application number: PCT/US1994/010174
Authority: WO
Inventors: Christine M. Foster; Robert F. Traver, Jr.
Original assignee: W. L. Gore & Associates, Inc.
Priority date: 1994-06-30
Filing date: 1994-09-09
Publication date: 1996-01-11
Also published as: AU7684994A

Abstract

A conductive shield is provided comprising a comb having a front face with openings and conductive columns and an insulative comb that fits within the conductive combs so that the openings and conductive columns are rendered non-conductive and is attached to a conventional right angle header by means for attaching. The remainder of the comb may be conductive or optionally treated by coating or painting with an insulative material so that exterior surfaces are rendered non-conductive.

Description

TITLE OF THE INVENTION

A CONDUCTIVE SHIELD

Field of the Invention

A conductive shield with optionally exterior insulative surfaces is provided for use with a right angle header of a high performance connector assembly. The conductive shield may be attached to ground or be left floating so as not to be attached to ground.

BACKGROUND OF THE INVENTION Many commercial and testing applications require that a coaxial signal line be fed directly to another electronic system such as a printed circuit board. High quality circuit interconnections such as the cable to PCB are difficult to achieve because of stringent electrical signal performance requirements with relatively limited space constraints. Such a connector or header must be miniature in scale but must meet stringent performance requirements resulting from high speed or high frequency data transmission. Conventional coaxial cable connectors and headers are designed to attach a miniature cable to a PCB via an assembly of small parts which owing to their size and complexity make them difficult to make and assemble and are quite expensive due to the intricate and labor intensive work required. This is particularly the case for right angled board mount units. Often for example, ground pins must be in a designated location to facilitate grounding. This leads to special design restraints.

U.S. Patent 4,914,062 relates to a shielded right angled header having a plurality of signal connecting posts and grounding posts in an evenly ordered pre-arranged manner. Each signal post is incorporated in thermoplastic insulation and covered by a shielding metallic shell. Each metallic shell is also attached to a ground post. The units of the shielded insulated signal post and ground post are held together by a plastic shroud to form a complete header. This type of unit is specifically designed for a particular arrangement of signals and is not adaptable to new arrangements without requiring the redesign of the entire header. No variability is provided. Moreover, this right-angled header is not easily adaptable to multirow connections.

U.S. Patent 4,867,707 relates to a shielded integrated contact connector assembly for coaxial and twin axial cables having housing and retention means for plugging into an array of closely spaced standard male pins in rows of a printed circuit board and other high density grouped signal configurations. This device is designed for a specific application and provides for no variability to suit other applications. Other connectors such as RF connectors provide shields that allow for some variability, all require a connection to ground and do not allow the shield to float. Many of these connectors also require a significant amount of board space.

There is a need for a modified header that improves the electrical performance of a connection yet allows for variability without affecting the form, fit, or function of the traditional header and its interface with electronic transmission systems.

SUMMARY OF THE INVENTION A conductive shield with optional exterior insulative surfaces is provided for mechanical attachment to a connector header having an array of right angled contact and ground pins including: a) a conductive comb having a top, a front face, optional rear wall and sides wherein the front face is provided with a plurality of openings and conductive columns between the openings, b) an insulative comb further including a series of insulating caps that fit within the openings and cover exposed inside surfaces of the columns of the front face, and c) a means of attaching the conductive comb and insulative comb to a connector header wherein the signal and ground pins of the header fit within the individual openings of the combs and are electrically isolated from each other by the insulating caps. The conductive comb is constructed from a material selected from the group including copper, copper alloys and aluminum or from a conductive plastic. The conductive plastic may include an engineering grade thermoplastic such as polyester that has been impregnated with a conductive metal such as copper, nickel, or stainless steel. The insulative comb may be constructed from a thermoplastic material. The means for attaching may include nuts and bolts, screws, and snap-in locks. The conductive comb may optionally be coated with an insulative material such as an epoxy or paint so as to render its exterior surfaces nonconductive. The insulative comb may be a separate component from the conductive comb. Alternatively, the insulative comb may be an integral part of the conductive comb. The conductive shield may be electrically attached to ground (i.e., in contact with ground pins of the header) or may alternatively be left floating so as not to be electrically attached to ground. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an exploded perspective of the conductive shield with separate insulative comb of the present invention having a four row header and printed circuit board. Figure 1a is a cross-sectional side view of the conductive shield assembly taken across line A-A of Figure 1 wherein line A-A is cut through the contact pins.

Figure 1b is a cross-sectional view of the conductive shield assembly taken across line B-B of Figure 1 wherein line B-B is cut through columns between the contact pins.

Figure 1c is a front sectional view of the conductive shield assembly shown in Figure 1.

Figure 1d is a close up perspective of a means for mounting showing a snap-in design. Figure 1e is a partial top view of the assembled shield and header and front view of where the assembly is attached to a printed circuit board.

Figure 2 is an exploded perspective of the conductive shield wherein the insulative comb is an integral part of the shield of the present invention with a four row header and printed circuit board. Figure 3 is an exploded perspective of the conductive shield wherein the insulative comb is an integral part of the shield of the present invention with a two-row header and printed circuit board.

Figure 4 is a printout of cross-talk data in a connector having a conventional 2 row header. Figure 5 is a printout of cross-talk data in a connector with the inventive shield and 2 row header.

DETAILED DESCRIPTION OF THE INVENTION A conductive shield with optionally insulative exterior surfaces is provided for use with a right angle header of a high performance connector assembly. Such a shield is desirable as it facilitates connection without electrical transmission interruption or transmission interference to a female connector with minimal effort or expense. No special treatment is required for the contact pins for use with this shield. Thus, this shield can be added to a previously installed header as a means to increase the electrical performance of the header. This shield provides significant flexibility over existing systems as the ground pins do not need to be in a predetermined location so that grounding can be achieved. Rather, this shield allows for the ground pins to be located anywhere in the array of contact pins. Grounding of the shield is optional.

The invention is best understood by reference to the accompanying drawings. Figure 1 shows an exploded view of the shield 2 with conductive comb 12, and a separate insulative comb 4 to be attached to a header 6 and printed circuit board 8. The shield 2 is also provided with means for attaching 10 the assembly to a right angle header 6. The right angle header 6 comprises a housing with an array of right angled signal and ground pins collectively identified as contact pins 26 that are subsequently attached to a printed circuit board 8. In the embodiment shown in Figure 1, the header 6 is a conventional four (4) row right angle header. Alternatively, other conventional right angle headers are also suitable. Figure 3 shows a two row right angle header with the shield 2.

In Figure 1, the conductive shield comprises a conductive comb 12 having a top surface 3, two sides 5a and 5b, and a front face 7 provided with an upper surface 11 and a plurality of conductive columns or fins 16 located below the upper surface 11. An optional rear wall 9 as shown in Figure 1a may also be provided. Openings 14 in the front face 7 are positioned between each conductive column 16. The top 3, two sides 5a and 5b, optional rear wall 9, and upper front surface 11 may be comprised of a conductive material. The exterior surfaces of the comb 12 may optionally be covered with an insulative coating or paint so as to render the outer surface nonconductive. Alternatively, the top 3, two sides 5a and 5b, optional rear wall 9, and upper front surface 11 may be comprised of a nonconductive material. The columns 16 must be comprised of a conductive material. A band

11a as seen in Figure 1c is located in the lower region of the upper front surface 11 may also optionally be conductive so as to electrically connect the columns 16.

A separate insulative comb 4 is also provided for the embodiment shown in Figure 1. This insulative comb 4 comprising a series of insulating caps 18 that fit within the openings 14 and over the columns 16 so as to electrically insulate the inner surfaces of the columns 16 from each other. When assembled with the header 6, the contact pins 26 are designed to be located within the openings 14 of the combs 12 and 4. The ground pins may be floating (i.e., not touching the surface so as to not be grounded) or may be touching the surface so as to be grounded.

The conductive comb 12 is preferably constructed of a conductive material including but not limited to copper, copper alloys, aluminum, and conductive plastics. Preferable plastics include polyetherimides, polyamides, acetals, polycarbonates end engineering grade thermoplastics such as polyethylene terephthalate, polybutylene terephthalate, and liquid crystal polymer. These plastics are rendered conductive by loading or impregnation with metal fillers such as fillers of copper, nickel, or stainless steel. An optional coating of epoxy or paint may cover the side walls 5a and b, top 3, optional rear wall 9 and upper front surface 11.

Alternatively, the conductive comb 12 may have sides 5a and b, top 3, optional rear wall 9, and the upper front surface 11 be comprised of a plastic such as those identified above so that these parts of the comb are not conductive. The columns 16 of the front face 7 however must be comprised of a conductive material such as those identified above.

The insulative comb 4 is constructed of a nonconductive material such as engineering grade thermoplastics including polyethylene terephthalate, polybutylene terephthalate and liquid crystal polymers. The insulative comb 4 is designed to fit within the spaces between the columns 16 so that the caps 18 of the insulative comb 4 fit snugly against the walls of the columns 16 of the conductive comb and remains intact when the header is then connected to the shield. The insulative comb 4 is necessary to prevent incidental contact between the contact pins 26 and the conductive comb 12 when the system is assembled.

Also shown in Figure 1 are the means for attaching 10 the floating shield to the standard header and printed circuit board. The means for attaching 10 in Figure 1 include a mounting bracket 20 and mounting screw 22 that is attached from the header side to a nut 24. The mounting bracket may also be provided with screws for attachment to the printed circuit board 8. Alternatively, the means for attaching 10 may be mounting brackets with a snap-in design wherein the shielded and insulating comb assembly are snapped in place onto the header without the use of additional nuts and bolts. Such an attaching means is shown in Figure 1d. Other means include female threads on the conductive comb 12 so that the bracket can be eliminated thereby providing for the shield to be screwed directly to the header.

Figure 1a shows a side view of the assembled system taken along line A-A that cuts through the contact pins. As can be seen in the Figure, the assembled conductive shield 2 with insulative comb 4 fit adjacent to the header shroud 6 so that the angle of the right angle contact pins 26 are within the openings of the caps 18 of the insulative comb 4. Figure 1b shows a side view of the assembled system taken along line B-B that cuts adjacent the contact pins 26. As can be seen in this Figure, the insulative face of a cap 18 separates each column of 4 contact pins from each other. Figure 1c shows a front view of the assembly where once again the insulating comb 4 separates and isolates each column of 4 contact pins. Contrary to conventional technology requirements, the ground pins may be located anywhere within the pin column.

Figure 2 shows a second embodiment of the invention wherein the conductive shield 2 has an insulative section as integral part of it thus eliminating the need for a separate insulative comb 4. In this embodiment, all surfaces of the comb 12' are conductive except for the exposed internal surfaces of the columns 16' and openings 14' which are rendered nonconductive by treating the originally conductive surface. This is accomplished by applying to the surface of the comb a nonconductive material such as epoxy or paint. Conventional coating treatments are suitable and include dip coating, electrostatically applications and painting. These parts may then be heated to cure the insulative layer applied. Alternatively, all surfaces of the shield are treated so as to be rendered nonconductive. The columns 16' are treated so as to have nonconductive surfaces but are internally conductive. A most preferred construction of this embodiment includes a conductive comb 12' constructed from aluminum that has been treated so that all surfaces have an epoxy thermoset coating. Alternatively, any of the conductive materials described above may be used and then treated so that the exterior surfaces are rendered nonconductive. Similar to the first embodiment, this conductive shield with interior combed nonconductive surface is mounted onto a conventional header by means for attachment 10 such as nuts and bolts, screws, or snap locks.

Other embodiments of the invention will be apparent to those skilled in the art from a consideration of this specification or practice of the invention disclosed herein. It is intended that the specification be considered as exemplary, with the true scope and spirit of the invention indicated by the accompanying claims.

Example A conventional 2 row right angle header was constructed having a specific grounding arrangement for which a specially designed shielding arrangement would be required. Cross-talk without the conductive shield was measured using a pulse generator to drive up to four (4) lines surrounding a quiet line which was sensed using a sampling oscilloscope. A readout of the cross-talk with the standard header but no conductive shield is shown in Figure 4.

A conductive shield was made for a two row right angle header. A conductive comb was manufactured from aluminum and had a front face of columns and openings similar to that shown in Figure 3. An insulative comb was molded from polyimide to form a tape having caps and openings to match the columns and openings of the conductive comb and was fitted within the openings and columns of the aluminum comb of the housing. This conductive shield was then attached to a standard right angle header. Testing procedures for measuring cross-talk were identical to those described above and results are shown in Figure 5. As can be seen by comparing Figures 4 and 5, the cross-talk was reduced by 50% with the addition of the conductive shield.

Claims

WE CLAIM:

1. A conductive shield for attaching to a right angle header having an array of right angled signal and ground pins comprising: a. a conductive comb having a top, optional rear wall, two sides, and a front face, said front face provided with a plurality of openings and conductive columns between the openings; b. an insulative comb further comprising a series of insulating caps that fit within the openings of the conductive comb and cover inside exposed surfaces of the columns; and c. a means for attaching the conductive comb with insulative comb to the connector header wherein the signal and ground pins of the header fit within individual openings of the conductive and insulative combs.

2. A conductive shield of Claim 1 wherein the conductive comb is constructed from a material selected from the group including copper, copper alloys and aluminum.

3. A conductive shield of Claim 1 wherein the conductive comb is constructed from a conductive plastic selected from the group of plastics including polyetherimides, polyamides, acetal, polycarbonates, polyethylene terephthalates, polybutylene terephthalates and liquid crystal polymers that have been impregnated with conductive metals selected from the group comprising copper, nickel, and stainless steel.

4. A conductive shield of Claim 1 wherein the conductive comb is further treated so that external surfaces of the comb are rendered nonconductive.

5. A conductive shield of Claim 1 wherein the insulative comb is constructed from a non-conductive material selected from the group including polyethylene terephthalate, polybutylene terephthalate, and liquid crystal polymers.

6. A conductive shield of Claim 1 wherein the means for attaching are selected from the group including nuts and bolts, screws and snap-in locks.

7. A conductive shield of Claim 1 wherein the insulating comb is a separate component.

8. A conductive shielded for attaching to a connector header having an array of right angled signal and ground pins comprising: a. a comb having a top, an optional rear wall, two sides, and a front face, said front face provided with a plurality of openings and conductive columns between the openings ; and b. means for attaching the comb to the connector header wherein the signal and ground pins of the header fit within individual openings of the comb.

9. A conductive shield of Claim 8 wherein the comb is constructed from a conductive material selected from the group including copper, copper alloys, aluminum, and conductive plastic and wherein exterior surfaces of the comb are further treated with an insulative material so as to render the surfaces nonconductive.