摘要:
In a flat flex cable, signal lines are surrounded by logic ground planes above and below which are viaed together left and right. The ground planes coupled with the flex cable dielectric determine characteristic the impedance and attenuation of the cable and provide differential signal EMI shielding. All signal layers and logic ground planes are enclosed within the two outermost shield layers which are viaed together left and right and around the connectors to enclose both signal layers and logic ground planes to provide common mode EMI shielding.
摘要:
A method for manufacturing multilayer flexible circuits is disclosed. The cross-sectional area of an unoccupied signal layer volume is initially determined. The unoccupied signal layer includes multiple conductive elements, and the unoccupied signal layer volume is formed between two of the conductive elements. Next, the thickness of an adhesive layer for filling the unoccupied signal layer volume is determined. Finally, the thickness of the adhesive layer is adjusted such that the adhesive layer only fills the unoccupied signal layer volume while the two conductive elements come in direct contact with a dielectric layer without any adhesive in between.
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.
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.