Tamper resistant card enclosure with improved intrusion detection circuit

摘要

A system for protecting an electronic device from mechanical intrusion attempt. An intrusion barrier able to detect mechanical intrusion by means of circuit traces which detect any change in the resistance characteristics of the electric circuit. These circuit traces function as a resistors and they are connected together to form a Wheatstone bridge. According to the present invention the logical lay-out of these connections is selected so that the voltage difference between two adjacent traces is minimized. In this way the current leakage effect is limited to the minimum.