Method of fabricating soldering pads and bonding pads on thin-film hybrid circuits

摘要

In a single fabrication process, this method simultaneously produces both Cu/Sn soldering pads which are ideal for soldering surface-mounted components and Ni/Au bonding pads which are ideal for Al wire bonding. For this purpose, a glass layer (6) based on SiO2 is additionally vapour-deposited on the copper layers (5) provided for soldering. An Al2O3 layer (7) is then vapour-deposited on the entire circuit and coated with a photosensitive polyimide resist or a photoresist (8) which is exposed above the soldering pads (13) and the bonding pads (12) and developed. After etching the Al2O3 layer (7) in the pad windows, the copper layer (5) of the bonding pads (12) which is laid bare can be electrolessly plated with nickel and gold after activation with a Pd activator solution. After etching the glass layer (6) on the soldering pads (13), the copper layer (5) of the soldering pads (13) which is laid bare is electrolessly nickel-plated.