01 June 2010
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Laser technology produces reliable welds in gold and copper

Gold and copper are known to be difficult metals to laser weld. They have high surface reflectance – exactly the same property that gives gold its lustrous appearance and makes it attractive as a jewellery metal – making it difficult for laser energy to penetrate below the surface.

However, both gold and copper absorb more strongly in some parts of the light spectrum than in others and, in particular exhibit increased absorbance of green light.

Laser and resistance welding systems supplier, Miyachi Europe has introduced the ML-8150C SHG Green Laser Welder, which has been specifically designed to produce consistent and reliable welds in gold and copper. The machine is intended for applications in the semiconductor and electronics manufacturing sector, including welding gold and copper wires to substrates.

The ML-8150C delivers laser energy with a wavelength of 532 nm, which is green light. The unit employs an SHG – second-harmonic generation – architecture, in which laser light is first produced at 1064 nm. Although this is in the infrared it is not well-absorbed by gold and copper. Miyachi's SHG design doubles the frequency of the light, halving the wavelength to 532 nm, and increasing by a factor of between 4.5 and 20 the energy absorbed by the metals to be. joined. The company claims that improved beam definition, coupled with higher power, raises the energy density of the laser by some nine times compared to its earlier product in this sector.

Paul Gay


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