GB2193604A

GB2193604A - Electrical shielding

Info

Publication number: GB2193604A
Application number: GB08713172A
Authority: GB
Inventors: Walter Phelps Kern
Original assignee: Teradyne Inc
Current assignee: Teradyne Inc
Priority date: 1986-08-05
Filing date: 1987-06-05
Publication date: 1988-02-10
Anticipated expiration: 2007-06-05
Also published as: CA1271819C; DE3723968A1; DE3723968C2; FR2602630B1; GB8713172D0; CA1271819A; JPS6342199A; FR2602630A1; JPH0239119B2; GB2193604B

Description

1 GB2193604A 1 SPECIFICATION Following is a description of preferred em-

bodiments of the device and method of the Electrical shielding invention, by way of example only with refer ence to the accompanying drawings in This invention relates to electrical shielding, 70 which:- and more particularly, in preferred embodi- Figure 1 is an isometric view of a broken- ments, to the coaxial shielding of spring pins. away portion showing one shield portion of The desirability of shielding elements of the preferred embodiment of the device; electrical circuits, in appropriate instances, is Figure 2 is a corresponding isometric view well known. Coaxially shielded spring pins for 75 illustrating an earlier stage in the preferred em use in connection with printed circuit boards bodiment of the method; ("PCBs") are known. Figure 3 is a diagrammatic plan view of a We have discovered that coaxial shielding broken away portion of the device; may be provided, reliably, at low expense and Figure 4 is a plan view on a smaller scale of consistently with high shielded element denan arrangement of said devices; sity, by providing, in accordance with a first Figure 5 is a sectional view taken at 5-5 of aspect of this invention, an insulator base hav- Fig. 3; and ing shielded element and grounding element Figure 6 is a corresponding sectional view mounting holes, the inner wall of a grounding showing a second device cooperating with a element mounting hole being in conductive 85 first in order to secure therebetween a spring electrical communication with a shield around pin.

a shielded element mounting hole and spaced There is shown in Fig. 3 an enlarged plan therefrom by insulating material. view of a portion of one of the devices, indi- According to a second aspect of this inven- cated generally at 10, of the invention. In use, tion, we provide an electrical shielding device 90 eight of these devices 10, the inner and outer comprising a base, formed of insulating ma- walls 12 and 14 of which are coaxially arcuate terial, and having therein a shielding hole and (O.D. 10 inches-25.4 cm) are abutted to form a ground hole, said shielding hole having posi- an arrangement annular in horizontal cross tioned therein a metallic shield and an insula- section, as shown in plan view in Fig. 4.

tor within said shield, an element hole being 95 Each device 10 has a base 16 formed by formed in said insulator, and said ground hole injection moulding of glass-filled (40%) poly having positioned therein an electrically con- phenylene sulphide (sold by Phillips Chemical ductive layer in electrical communication with Company under the trademark RYTON R-4).

said shield. Extending through base 16 are cylindrically an- In a third alternative aspect thereof, the in- 100 nular layers 18, 20 of dull (for better adhe- vention provides a shielding device, as for sion) electroless nickel. The layer extends in a spring pins, by providing a base having shield- continuum along the floor 22 and sides 24, ing holes, grounding holes, and a trough con- 26 of blind slot 27 and therefrom in portions necting them with an interconnected covering, 28, 30 of counterbore 32 and cylindrical por and by providing within the shielding holes in- 105 tion 34 within hole 36. Annular cast tetrafluo sulators with element holes therethrough. roethylene insulator 38 casting material (sold In preferred embodiments, the insulator base by DuPont under the trademark TEFZEQ is is a unitary structure moulded from polypheny- within electroless nickel layer 18, 20 and fills lene sulphide reinforced with glass and con- slot 27. Hole 40 with counterbores 42 is pro taining a multiplicity of spring pin mounting 110 vided in insulator 38.

holes oriented in pairs, one spring pin mount- As shown in Fig. 6, two units 10 are ing hole of each pair being spaced by a poly- brought together with spring pins indicated tetrafluoroethylene insulating annulus from an generally at 42 held therebetween in one set electroless nickel shield around the annulus, of counterbores 32, 42 for each spring pin.

the other spring pin mounting hole of each 115 (Counterbores 32, 42 are provided at each pair being conductively connected to the shi- end of holes 36, 40 so that the ring made up eld by a continuum of the electroless nickel. of units 10 may be used with either surface The invention provides, in a yet further as- up, to permit moulding a single base 16 even pect thereof a method of fabricating a shield- though two configurations of base 16 are ing device which comprises forming an insulat- 120 needed, for example alternating around the an ing base, providing therein a first hole and a nulus, one being a mirror image of the other.

second hole, coating said base over said holes The ring 44 may be held together and down with a layer of conductive material, placing in on PCB (not shown) by screws (not shown), said first hole an insulating material with a and permits easily releasable connection there third hole therethrough, and electrically inter- 125 through with another PCB (not shown).

connecting, the coatings in said first and sec- Current passing through spring pins in insu- ond holes. lator 38 is electrically shielded by electroless In a perferred embodiment a blind slot is nickel completely therearound, the latter being provided between the two holes before platelectrically connected with the adjacent ground ing. 130 spring pin through a continuing layer of elec- 2 GB2193604A 2 troless nickel. 12. A shielding device, as for spring pins, The device is made by first moulding the is provided by providing a base having shield- base 16, giving it an overall thickness about ing holes, grounding holes, and a trough con 0.020 inches (0.0508 cm) greater than ulti- necting them with an interconnected covering, mately wanted. The entire piece is then given 70 and by providing within the shielding holes in- a coating of dull electroless nickel, which ex- sulators with element holes therethrough.

tends over top, bottom and throughout the 13. An electrical shielding device compris- large and small hole, counterbore, and slot as ing an insulator base having shielded element shown in the uncoated piece shown in Fig. 2. and grounding element mounting holes, the in- About 0.010 inch (0.0254 cm) thickness is 75 ner wall of a grounding element mounting hole then removed from top and bottom, removing being in conductive electrical communication with it the nickel coating thereover. Bushing with a shield around a shielded element 38 is then cast. mounting hole and spaced therefrom by insu- Other embodiments will occur to those lating material.

skilled in the art. 80 14. An electrical shielding device substan- tially as hereinbefore described with reference

Claims

CLAIMS to and as shown in the accompanying draw-

1. An electrical shielding device comprising ing.

a base, formed of insulating material, and hav- 15. A method of fabricating a shielding de- ing therein a shielding hole and a ground hole, 85 vice substantially as hereinbefore described said shielding hole having positioned therein a with reference to the accompanying drawing.

metallic shield and an insulator within said shi eld, an element hole in said insulator, and said Published 1988 at The Patent office, State House, 66/71 High Holborn, London WC 1 R 4TP. Further copies may be obtained from ground hole having positioned therein an elec- The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BF15 3RD.

trically conductive layer, in electrical Communi- Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.

cation with said shield.

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2. A device according to claim 1, in which said shield and said layer are coatings.

3. A device according to claim 2, in which one continuous coating provides said coatings and said electrical communication.

4. A device according to claim 3, in which a trough connecting. said shielding hole and - said ground hole is covered by said continu- ous coating.

5. A device according to claim 3 or 4, in which said continuous coatings is of plated metal.

6. A -device according to claim 5, in which said metal is electroless nickel.

7. A device according to any preceding claim, in which said base and said insulator are of plastics.

8. A device according to claim 6, in which said insulator is glass-loaded polyphenylene sulphide and said insulator is of castable po- I lytetrafluoroethylene, and said metal is electro less nickel.

9. A method of fabricating a shielding de- vice which comprises forming an insulating base, providing therein a first hole and a sec ond hole, coating said base over said holes with a layer of conductive material, placing in said first hole an insulating material with a third hole therethrough, and electrically inter connecting the coatings in said first and sec ond holes.

10. A method according to claim 9, in which said base is coated overall, and top and bottom surfaces are thereafter cut to electri cally segregate said first and second holes.

11. A method according to claim 10, in which -a channel connecting said first hole and said second hole is coated to electrically inter connect said first and second holes. -