Novel Laser Soldering Process for Flex Circuit Attachment
Original Publication Date: 1988-Aug-01
Included in the Prior Art Database: 2005-Feb-15
A soldering process concerns the use of laser energy to achieve highly localized heating and very short soldering cycle time in combination with a forming-gas atmosphere having a 90% N2/10% H2 mixture ratio. The process is most advantageous for flex circuit bonding because of the minimal area heated and the elimination of flux and subsequent cleaning operations. The laser energy from laser 10 and the forming gas via inlet 12 are supplied coaxially through a 400 mm optical fiber 14 and a fine stainless steel tube 16, respectively, as shown in the figure. The inner surface of the tube 16 which is exposed to the laser radiation is coated with a thin TiN film. The film acts to further reflect the radiation reflected by the surface of solder 20 located on a polymer substrate 22.