Method of manufacturing a venting device for tamper resistant electronic modules

摘要

A tamper resistant enclosure for an electronic circuit includes an inner copper case, a tamper sensing mesh wrapped around the inner case, an outer copper case enclosing the inner case and the tamper sensing mesh, and a venting device forming a vent channel from inside the inner case to outside the outer case, the vent channel passing between overlapping layers of the tamper sensing mesh and having at least one right angle bend along its length. The venting device consists of two strips of a thin polyamide coverlay material laminated together along their length, and a length of wool yarn sandwiched between the two thin strips and extending from one end of the strips to the other end of the strips to form the vent channel. The length of yarn follows a zig-zag path between the first and second strips, the zig-zag path including at least one right angle bend.

主权项

1. A method comprising:
providing two strips of coverlay material, each strip of coverlay material having a length that is greater than its width, and each being gas-impermeable; providing a length of gas-permeable semisolid material interposed between the two strips of coverlay material, the length of the gas-permeable semisolid material extending an entire length of the lengths of the strips of coverlay material; laminating the two strips of coverlay material together in a sandwich with the gas-permeable semisolid material in between, so as to form a venting device having a vent channel between the strips of coverlay material, the vent channel allowing a gas to flow therethrough from one end of the strips to an opposing other end of the strips; and inserting the venting device into a tamper resistant enclosure having two tamper resistant meshes opposed to each other, the venting device being inserted directly between the two tamper resistant meshes, the two tamper resistant meshes being connected to a circuit card enclosed within the tamper resistant enclosure so that the circuit card is responsive to damage to the two tamper resistant meshes by nullifying information on the circuit card.