US 6,408,758 B1Granted

Photoetched-filament pyrotechnic initiator protected against electrostatic discharges

AssigneeLivbag SNC

InventorJean-René Duguet

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Abstract

The present invention relates to the field of electropyrotechnic initiators comprising a thick-film multifoil circuit. The electrical circuit is photoetched on an insulating support (16). It consists of a resistive first foil having a central part (17) of constant width. This first foil is covered, except on the central part (17), by two conducting areas (28, 29) made of copper. The circuit (18) has an outline consisting of curved lines whose radius is greater than 7×10−4 m and whose shortest distance from the edge of the support (16) is at least 35×10−5 m. Such an initiator has an enhanced electrostatic discharge resistance.

Claims7

Dependent claims

Electropyrotechnic initiator (1) protected against electrostatic discharges, comprising:

inside a fragmentable container (2) closed and supported by an overmoulding (6), an initiation head consisting of an impermeable wall formed by a solid body (3) of height h which has a plane upper face (9) and which grips, over its entire height h, a glassy structure (10, 11) penetrated by two electrodes (12, 13) in the form of pins, said electrodes each having one end which protrudes from said plane upper face, this protrusion allowing them to be electrically connected to an electrical thick-film multifoil circuit (18) supported by an insulating support (16) which rests on said plane upper face and is itself penetrated by said electrodes, said circuit having a flat resistive heating element (17) connected to said electrodes via two separate conducting metal areas (28, 29) lying on said support, each area being in contact with one of the two electrodes, said flat element and said metal areas being covered with a pyrotechnic initiating composition (19), characterized in that:
said thick-film multifoil circuit (18) has the overall shape of an “S” and comprises a first film consisting of a first foil (24) made of a resistive metal alloy, having a thickness of between 2×10−6 m and 7×10−6 m, adhesively bonded to said support and penetrated by said electrodes, said first foil having a shape which has, between the electrodes, a central part forming the flat resistive element (17) and the external outline (25) of which first foil, except for said central part, consists of curved lines whose radii of curvature are greater than 7×10−4 m, said first foil being covered, except for said central part, with a second, conducting, metal film (27) serving to form the metal areas (28, 29) which are penetrated by said electrodes and which have a shape and thickness which are similar to those of the parts of the first foil that they cover.

Dependencies are inferred from the claim text.

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Abstract

Electropyrotechnic initiator (1) protected against electrostatic discharges, comprising:

inside a fragmentable container (2) closed and supported by an overmoulding (6), an initiation head consisting of an impermeable wall formed by a solid body (3) of height h which has a plane upper face (9) and which grips, over its entire height h, a glassy structure (10, 11) penetrated by two electrodes (12, 13) in the form of pins, said electrodes each having one end which protrudes from said plane upper face, this protrusion allowing them to be electrically connected to an electrical thick-film multifoil circuit (18) supported by an insulating support (16) which rests on said plane upper face and is itself penetrated by said electrodes, said circuit having a flat resistive heating element (17) connected to said electrodes via two separate conducting metal areas (28, 29) lying on said support, each area being in contact with one of the two electrodes, said flat element and said metal areas being covered with a pyrotechnic initiating composition (19), characterized in that:
said thick-film multifoil circuit (18) has the overall shape of an “S” and comprises a first film consisting of a first foil (24) made of a resistive metal alloy, having a thickness of between 2×10−6 m and 7×10−6 m, adhesively bonded to said support and penetrated by said electrodes, said first foil having a shape which has, between the electrodes, a central part forming the flat resistive element (17) and the external outline (25) of which first foil, except for said central part, consists of curved lines whose radii of curvature are greater than 7×10−4 m, said first foil being covered, except for said central part, with a second, conducting, metal film (27) serving to form the metal areas (28, 29) which are penetrated by said electrodes and which have a shape and thickness which are similar to those of the parts of the first foil that they cover.