Patent DE-102007052969-A1 (DE)
Title: Electrically contacting thin-film conducting webs to organic carrier by producing openings in dielectric carrier of thin-film circuits, comprises removing large part of thick material of the dielectric carrier on a rear side of circuit
Inventor: ZIMMER KLAUS
IPC: H05K3/00
Filed: 2007-11-07
Abstract: The method for electrically contacting thin-film conducting webs to an organic carrier by producing openings in dielectric carrier of thin-film circuits for removing a thin layer (2) or layers lying on the carrier and for producing an electrical contact by using the opening, comprises removing the large part of the thick material of the dielectric carrier on a rear side of the thin-film circuit with a pulsed laser beam in two steps, so that the surface of the opening in the carrier follows the energy density distribution of the laser beam and then removing the remainders of the carrier. The method for electrically contacting thin-film conducting webs to an organic carrier by producing openings in dielectric carrier of thin-film circuits for removing a thin layer (2) or layers lying on the carrier and for producing an electrical contact by using the opening, comprises removing the large part of the thick material of the dielectric carrier on a rear side of the thin-film circuit with a pulsed laser beam in two steps, so that the surface of the opening in the carrier follows the energy density distribution of the laser beam and then removing the remainders of the carrier with the same laser beam, so that the laser energy density is larger than ablation energy density of the carrier material until the destruction energy of the thin layer is not exceeded and parameter of the laser beam such as the energy density distribution and laser-beam surface impact is selected for the removal, so that a force applied during the ablation removal not guides for the impairment of the thin layer but for the removal of the thin-layer carriers and the produced opening is partially or completely coated or filled with a conducting material. The pulsed laser beam has a wavelength in the ultraviolet region. The pulse duration of the laser beam is smaller than 1 mu s. The energy density of the laser beam is selected, so that no surface topographies arise during the laser ablation. The surface topographies are not based on the energy density distribution. The material removal is carried out by pulsed laser beam in two or several steps with decreased energy of the laser beam. The laser-supported material removal is carried out by a process gas such as helium with less density. Viscous or liquid conducting adhesive is used as contact material paste. The produced openings have geometries of circles or polygons. During the utilization of polyimide as the organic carrier, the first removal step is carried out with a laser pulse number of 80-150 pulses and the laser energy density of 500-1000 mJ/cm 2>and the second removal step is carried out with a laser pulse number of 150-250 pulses and the laser energy density of 200-500 mJ/cm 2>. The conducting adhesive is introduced in a screen printing. A stabilizing material, a film or a liquid is introduced on a front side of the thin-film conducting web.