Electricity: electrical systems and devices – Discharging or preventing accumulation of electric charge – Specific conduction means or dissipator
Patent
1984-01-03
1985-12-17
Eisenzopf, Reinhard J.
Electricity: electrical systems and devices
Discharging or preventing accumulation of electric charge
Specific conduction means or dissipator
361212, 361 56, 361 91, 338 21, 357 2313, H02H 320
Patent
active
045595798
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a device for the protection of an electronic component and/or circuit against the disturbances (voltages) generated by an external electromagnetic field, such as the so-called EMP (Electro Magnetic Pulse) attributable to a disintegration of atomic or nuclear nature.
BACKGROUND OF THE INVENTION
As known, the presence of an electromagnetic field causes the appearance of voltages in electronic components or circuits, which voltages may cause burn-out and destruction of the components. A protection is thus needed against these parasitic voltages and is the more difficult to establish, the more the field in question is liable to appear suddenly with a short rise time which may reach some ten nanoseconds in particular cases, which for example represents the case of the aforesaid EMP.
It is known that a protection of this kind may be effected by enclosing the circuit or component to be protected within a shield or Faraday cage. However, this protection proves inadequate because these components or circuits necessarily have electrical connections with the outside, which form antenna in the presence of an extraneous field and permit penetration of parasitic charges into the element which is to be protected.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a protective device which makes it possible to avoid the aforesaid disadvantages, and this is effected by outwardly draining off the parasitic charges at the level of each of the connections of the element to be protected.
According to the invention, there is provided a device for the protection of an electronic device against an external electromagnetic field, said electronic device having output and input connections, said protection device comprising electrical connection means, said connection means comprising a first material and a second material said first material having an electrical conductivity which increases under the action of said external electromagnetic field, said second material being electrically conductive and being positioned on to said first material, said connection means being positioned between and in contact with, by means of said first material, each of said connections of said electronic device and a drain or a store for charges produced by said field.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 illustrates a first embodiment of the device according to the invention, applied to the protection of an electronic component,
FIG. 2 illustrates a second embodiment of the device according to the invention, applied to a housing of the "chip carrier" type,
FIG. 3 is a view in partial cross-section of the device of FIG. 2,
FIG. 4 illustrates a third embodiment of the device according to the invention, equally applied to a housing of the "chip carrier" type,
FIGS. 5, 6 and 7, illustrate three embodiments of the device according to the invention applied to the protection of an electronic circuit on a card, and
FIGS. 8, 9 and 10, illustrate three embodiments of the device according to the invention applied to a connector for cards bearing electronic circuits.
In the various figures, identical references denote identical elements and the actual dimensions of these elements have not been adhered to for the sake of clarity of the drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 thus illustrates an electronic component C provided with four connecting terminals 1,2,3 and 4, which are each connected in conventional manner by a conductive wire 10 to conductors, for example formed by the strips on the base of the housing B (ceramic or plastic) which carries the component, denoted by 11,12,13 and 14, respectively. In this example, the connection 3 and the strip 13 form the ground connection for the device.
According to the invention, a frame is provided enclosing the component close to the same, formed by a layer V of a varistance material covered by a conductive el
REFERENCES:
patent: 3742420 (1973-06-01), Harnden, Jr.
patent: 3743897 (1973-07-01), Harnden, Jr.
patent: 3743996 (1973-07-01), Harnden, Jr.
patent: 3896480 (1975-07-01), Harnden, Jr.
patent: 3916366 (1975-10-01), Jefferson
patent: 4045712 (1977-08-01), De Tommasi
Eisenzopf Reinhard J.
Thomson - CSF
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