Tailored Beam Shaping for Laser Spot Joining of Highly Conductive Thin Foils

Laser spot joining of thin metallic foils in the order of 100 micrometer and below has a number of interesting applications in electronic industry. However, high thermal conductivity and thermal expansion of common materials largely prohibit spot joints with a sufficiently large contact area needed to satisfy mechanical and electrical requirements. Of the numerous possibilities to positively influence the process of such joints we investigateusing a pulsed Nd:YAG laser to generate spot joints of thin foils in combination with a beam shaping optic to tailor the temperature profile during laser spot joining of thin foils. This allows for increased contact area, stabilized process behavior and offers the potential for joining ultra thin foils far below 100 μm. Different configurations are examined, results are presentedand discussed, mainly in terms of their generalimpact on the micro joining process.