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The mechanism and capability of the new thick film multilayer interconnection technology using a neodymium-doped yttrium aluminum garnet (Nd-YAG) laser have been theoretically and experimentally described. The mechanism for the conductor pattern formation involves the softening phenomenon of the glass and the thermosetting phenomenon of the organic binder, contained in a thick film conductor paste, by continuous-wave (CW) laser beam energy. In the via hole formation, small holes can he drilled by a pulsed laser beam without damage to the under conductor layer, because at constant peak power drilling rate per shot decreases with the increase in depth, that is, with the increase in the number of shots. The conductor size and via hole size formed by the new technology are mainly affected by the laser beam diameter. The minimum beam diameter is limited by the melting phenomenon of a conductor metal for the conductor formation and the substrate tolerance for the via hole formation. Possible conductors and via holes are 25-µm wide with l0-µm thick gold and 18-µm diameter with 30-µm thick crystallizable glass, respectively.