FR2602630A1 - ELECTRICAL SHIELDING DEVICE AND METHOD - Google Patents

Abstract

ELECTRICAL SHIELDING DEVICE COMPRISING A BASE 16, SAID BASE BEING MADE OF AN INSULATING MATERIAL AND COMPRISING INSIDE A SHIELDING HOLE AND A GROUNDING HOLE, A METAL SHIELDING 18, 20 PROVIDED WITH SUCH A SHIELDING HOLE THE SURROUNDING AREA, AN INSULATOR 38 INSIDE THIS SHIELD AND A BASIC HOLE 40 IN THE SAME, AND SUCH AN EARTHING HOLE INCLUDING AN ELECTRICALLY CONDUCTIVE LAYER 34, SAID LAYER WHICH IS IN ELECTRICAL COMMUNICATION WITH THE SAME .

Description

Electrical shielding device and method.

  The invention relates to an electrical shielding device and method, and more particularly, in embodiments

  preferred, it relates to the coaxial shielding of spring pins.

  It is well known that it is desirable to have shielding elements for electrical circuits, in appropriate cases. Coaxially shielded spring pins 10 intended for use in

  connection with printed circuit boards (PCI) are known.

  It has been discovered that reliable coaxial shielding can be obtained at low cost and with a high density of shielded elements by providing an insulating base comprising mounting holes for shielded elements and grounding elements, the inner wall of the earthing element mounting hole being in electrically conductive communication with a shield around the mounting hole

  shielded element and spaced therefrom by an insulating material.

  In preferred embodiments, the insulating base is a unitary structure molded of glass-reinforced polyphenylene sulfide and containing a plurality of spring pin mounting holes oriented in pairs, one spring pin mounting hole of each pair. being spaced apart by a polytetrafluoroethylene insulating ring of chemical nickel shielding around the ring, the other spring pin mounting hole of each pair being conductively connected to the shielding by a continuum of the

chemical nickel.

  According to another aspect of the invention, it has been discovered that such a coaxial shielding device can be produced by forming an insulating base comprising a pair of through holes, by plating the base with a metal, by removing the metal from the surfaces. upper and lower of the base, and forming in one of the holes a ring of insulating material. According to a preferred embodiment, a slot

  blind is provided between the two holes before plating.

  A description is now given of embodiments

  - 2 - preferred of the device and method of the invention, description in

  which refers to the accompanying drawings in which: Figure 1 is a perspective view of a cutout portion showing a shielded portion of the preferred embodiment of the invention, Figure 2 is a corresponding perspective view showing a previous step of the method of implementing the method, FIG. 3 is a schematic plan view of a cut-out part of the device, FIG. 4 is a plan view on a smaller scale of an arrangement of said devices, FIG. 5 is a sectional view along 5-5 of Figure 3, and Figure 6 is a corresponding sectional view showing a second

  device cooperating with a first so as to fix between them a spring pin.

  In Figure 3 is shown a plan view on a larger scale of a portion of one of the devices, generally designated 10, of the invention. In use, eight of these devices 10, the internal and external walls 12 and 14 of which are curved and coaxial 20 (external diameter of 25.4 cm) are brought into abutment to form an annular arrangement in horizontal section, as shown by the view in

plan of figure 4.

  Each device 10 includes a base 16 formed by injection molding of polyphenylene sulfide filled with glass (40%) (sold by Phillips Chemical Company under the trademark RYTON R-4). Through the base 16 extend annular and cylindrical layers 18, 20 of a matte chemical nickel (for better adhesion). The layer extends by forming a continuum along the base 22 and the sides 24, 26 of the blind slot 27 and from there into portions 28, 30 of the counterbore 32 30 and of the cylindrical part 34 located in the hole 36. The casting material of the annular element forming the tetrafluoroethylene insulator 38 (sold by DuPont under the registered trademark TEFZEL) is inside the layer of chemical nickel 18, 20 and fills the slot 27. The hole

  comprising the counter-bores 42 is provided in the insulator 38.

  As shown in FIG. 6, two units 10 are assembled, - 3 spring pins indicated generally at 42 being held together in a set of counter bores 32, 42 intended for each spring pin. The counter-bores 32, 42 are provided at each end of the holes 36, 40 so that the ring formed by the 5 units 10 can be used while one or the other of the surfaces is located at the top, to allow molding a single base 16 even if two basic configurations 16 are required, alternating for example around the ring, one constituting a symmetrical image of the other. Ring 44 can be held and fixed to a PCI (not shown) by screws (not shown) and allows easy connection

  removable with another PCI (not shown).

  In operation, the current flowing through the spring pins of the isolator 38 is protected electrically and completely all around by the chemical nickel, the latter being electrically connected to the adjacent spring ground pin via

  of a continuous layer of chemical nickel.

  The device is produced by starting by molding the base 16, giving it an overall thickness greater than about 0.5 mm than that which is desired to finish. The entire part is then coated with a coating of matte chemical nickel, which extends over the upper part, the lower part and inside the large hole and the small hole, the counter bore and the slot, as shown for the part not covered in FIG. 2. A thickness of approximately 0.25 mm is then removed from the upper part and from the lower part, by removing it with the nickel coating which covers it. The socket

38 is then cast.

  Other embodiments will appear to those skilled in the art.

-4

Claims (11)

  1. An electrical shielding device comprising a base (16), said base being made of an insulating material and comprising inside a shielding hole and a grounding hole, a metal shielding (18, 20) being arranged in said shielding hole surrounding it, an insulator (38) inside said shielding and an elementary hole (40) in said insulator, and said grounding hole inside comprising an electrically conductive layer   (34), said layer being in electrical communication with said shield.   2. Device according to claim 1, in which the shielding and the layer are coatings.   3. Device according to claim 2, in which a coating   continuous constitutes said coatings and said electrical communication.   4. Device according to claim 3, wherein the coating continuous is metal plate.   5. Device according to claim 4, in which the metal is chemical nickel.   6. Device according to claim 2, in which the base and   the insulator are made of plastic.   7. Device according to claim 6, wherein the insulator is made of glass-filled polyphenylene sulfide and the insulator is of moldable polytetrafluoroethylene, and the metal is chemical nickel. 25 8. Device according to claim 3, wherein a bowl connecting the shielding hole and the earthing hole is   covered by said continuous coating.   9. A method of manufacturing a shielding device comprising forming an insulating base (16), forming therein a first hole and a second hole, coating said base on the holes by means of a layer of conductive material (18, 20, the placing in the first hole of an insulating material (38) through which a third hole (40) passes, and the electrical interconnection of the coatings   in said first and second holes.   10. The method of claim 9, wherein the base is coated as a whole and the upper and lower surfaces are then cut to electrically separate said first and second holes. 11. The method of claim 10, wherein a channel connecting said first hole and said second hole is coated so as to   establish said electrical interconnection.