Solar / Photovoltaic Manufacturing

Lasers are used for creating openings in the dielectric passivation layer for ohmic contact. Aluminum paste is screen printed to this surface and a subsequent thermal annealing process alloys the aluminum with the laser-exposed silicon to form a good ohmic contact. A typical 6 inch PERC cell will have about 155 laser-scribed lines which are longer than 156 mm, 40-50 µm wide, and are separated by 1 mm. The aggregate length of the PERC scribes on a single wafer is approximately 25 m. The target processing time can be as fast as one second per wafer, which equates to a 25 m/s required scribing speed. Fast two-axis galvo scanners as well as spinning polygon scanners can achieve such speeds. Please see Newport.com for additional information on Solar Panel Manufacturing.

Precision micromachining achievable with UV lasers allows more circuits to fit on a single panel, increasing the net usable area. Moreover, UV wavelengths are absorbed by a variety of materials in PCBs, from copper to polyimide films, thus providing a onesolution-for-all-materials-and-processes kind of flexibility. For example, the high beam intensity achievable with tighter focus UV can remove copper, while lower beam intensity achieved by reducing laser power can cut dielectric material without damaging the bottom copper layer. See Industrial PERC Solar Cell Processing with a High Power Nanosecond Pulsed Laser for additional information. While PV manufacturers are focusing on increasing solar cell efficiencies and reducing manufacturing costs, many of them are showing interest in CIGS TF solar cell technology. In CIGS solar cells, metallic Molybdenum TF deposited on a glass substrate is used as a back contact. Typically IR or green DPSS Q-switched lasers are used to process electrically isolating scribes on Molybdenum thin films. See Molybdenum Scribing In CIGS TFPV Solar Cells for additional information.