MIL-PRF-31032/3B, PERFORMANCE SPECIFICATION SHEET: PRINTED WIRING BOARD, FLEXIBLE, SINGLE AND DOUBLE LAYER, WITH OR WITHOUT PLATED?THROUGH HOLES, WITH OR WITHOUT STIFFENERS, FOR SOLDERED PART MOUNTING (15 JUN 2010)., This specification covers the generic performance requirements for flexible, single and double sided (one or two conductor layers) printed wiring boards (hereafter designated printed board) with or without plated holes and with or without stiffeners that will use soldering for component/part mounting (see 6.1.1).