Patent ID: 6666379
Filing Date: 2003-12-23
Classification: G06K

Abstract:
A method of fabricating a wireless radio frequency identification device comprising:providing a substrate having conductive lines formed thereon, the conductive lines comprising an antenna; conductively bonding an integrated circuit chip and a battery to the conductive lines on the substrate; providing a visible spectrum colored liquid resin and a visible spectrum substantially colorless liquid hardener, the liquid hardener having a visible spectrum colorless fluorescent material therein; combining and mixing the liquid resin and the liquid hardener into a liquid epoxy mixture having a volumetric ratio of resin to hardener of at least about 2, the liquid epoxy mixture not contacting the substrate during said combining and mixing; impinging radiation onto the liquid epoxy mixture effective to cause the fluorescent material within the liquid epoxy mixture to fluoresce within the liquid epoxy mixture, the liquid epoxy mixture not contacting the substrate during said impinging; from the fluorescing fluorescent material within the liquid epoxy mixture, first determining degree of homogeneity in the liquid epoxy mixture; concluding desired degree of homogeneity from the first determining or continuing the mixing at least until such time that desired degree of homogeneity is achieved from impinging and determining degree of homogeneity in the liquid epoxy mixture from the fluorescent material fluorescing within the liquid epoxy mixture; only after achieving the desired degree of homogeneity from the impinging and determining relative to the liquid epoxy mixture without the liquid epoxy mixture contacting the substrate, applying the liquid epoxy mixture onto the substrate effective to encapsulate the chip and battery within the liquid epoxy mixture on the substrate; and after the applying, curing the liquid epoxy mixture into a solid mass which encapsulates the chip and battery and comprises a wireless radio frequency identification device.