Tamper-responding encapsulated enclosure having flexible protective mesh structure

#1. Field of the Invention

#This invention relates generally to detection of intrusion into electronic assemblies, and more particularly, to the detection of intrusion by mechanical means for the purpose of reading the data stored in a memory.

#2. Description of the Related Art

#The foregoing and other objects, aspects and advantages will be better understood from the following detailed description of a preferred embodiment of the invention with reference to the drawings, in which:

#FIG. 1 is a schematic perspective diagram of components that will be included within an enclosure;

#FIG. 2 is a schematic perspective diagram of a circuit board partially wrapped with a flexible mesh structure;

#Referring now to the drawings, one exemplary enclosure according to the invention is shown in perspective view in FIGS. 1-4. FIGS. 5A-5F illustrate cross-sectional views of the flexible mesh that produces many benefits of the invention. More specifically, referring to FIG. 1, the internal components within the enclosure are shown in an exploded perspective view. In FIG. 1, a circuit card 24 is provided which contains thereon the various components for encryption and key storage in volatile memory 16, and the battery and the protection circuitry for the volatile memory for the encryption/decryption facility. The components other than the volatile memory 16 are designated generally as 26, all being shown conceptually. These components may also include a battery. The specific location, number and function are not critical to this invention.

#Disposed over each side of the circuit card 24 are a pair of plastic preforms 27 and 28 which fit over the components and provide the proper control surface or form-factor for the wrapping of the mesh member which will be described presently. If the circuit card 24 employs pins, then holes (unnumbered) or slots to receive such pins are provided in preform 28. The circuit card 24 and the preforms 27 and 28 are stacked in superimposed relationship so as to receive a flexible mesh structure (e.g., mesh member) 31 wrapped therearound which will form the barrier against any unauthorized attempts at mechanical, chemical, or ionizing intrusion to the circuit card 24.

#As shown in FIG. 5F, discussed below, the flexible mesh structure 31 includes a screen-printed resistive conductive pattern 50 on one side and a photolithographically formed resistive wiring pattern 51 on the other side. The flexible mesh structure 31 includes electric leads 38-40 that are connected to the resistive patterns 50, 51. For example, the lead 39 could connect to the outer resistive pattern 50 while another lead 38 could connect to the inner resistive wiring pattern 51. Electrical lead 40 could be a common voltage supply for both resistive conductive patterns 50, 51. The foregoing external connections to the flexible mesh structure 31 are merely exemplary and, as would be known by one ordinarily skilled in the art given this disclosure, many other forms of electrical connections can be made with the inventive structure. The mesh will also be formed with a pair of side flaps 41 which serve to protect the edges of the circuit card.