www.solar-pv-management.com Issue II 2010
PV PROCESSEQUIPMENT
SPI Lasers www.spilasers.com
Pulsed fiber laser
Pulsed fiber lasers have been increasingly adopted in PV manufacturing for a broad range of solar applications both in R&D and in volume production. The compact nature of the pulsed laser and the high wallplug efficiency makes it ideal for integration into production equipment. The laser can be used for a diverse range of applications such as; welding, soldering, scribing, micro-machining, marking, annealing and thin film ablation.
The current solar market is roughly divided between silicon and thin film based technologies and in both areas the pulsed fiber laser is able to find numerous applications.
In thin film processing the use of the pulsed fiber laser for non- contact patterning is becoming increasingly widespread; it offers a greener and more compact solution. Nanosecond pulsed fiber lasers are commonly used for P1 patterning, selectively removing either molybdenum in CGIS or ITO in amorphous silicon technology, generating line widths in order of 30µm. The directly modulated design of SPI‘s pulsed fiber laser offers end users greater flexibility in optimising the pulse characteristics required for a particular scribe. A key differentiator is the ability to vary the length of the pulse which in turn gives greater control over parameters such as peak power, pulse energy and pulse repetition rate all of which can impact the material removal process.
Within the silicon solar cell manufacturing there are a number of processes carried out by the pulsed fiber laser. These include
STIL www.stilsa.com
STIL-DUO Sensor
STIL proposes high-performance sensing solutions based on innovative optical principles. These solutions allow the manufacturers both to optimize the design stage – the sensors providing a better knowledge of the physical characteristics – and to improve the monitoring of the production process, thanks to an online control of characteristics that were previously unavailable, except in laboratories.
In order to fulfill the in-situ control requirements, STIL introduces the new STIL-DUO sensor implementing a novel type of optical measuring principle, based on an enhancement of the well- known Spectroscopic Analysis of White Light Interferograms (SAWLI).
This new type of sensor allows performing surface microtopography, such as bow, warpage, texture or roughness. It also allows to measure film thickness from 0.6 to 100 µm, as well as blind TSV depth with diameter as small as 3 µm and with aspect ratio greater than 10:1.
The originality of the STIL method lies in the position of the reference surface, leading to a significant reduction of the impact of vibrations on measurements. As a result the potential subnanometric accuracy of interferometric microscopy is effective. As this non contact optical method requires no vertical scanning, it is fully compatible with integrated inspection systems. The point sensor configuration enables performing very high speed measurements as a single profile scan across the object is sufficient to measure its microtopography. Moreover it leads to a very easy integration thanks to its small size optical pen and to its optical fiber link to the opto electronic controller.
STIL has synthesized its experience in non contact measurement sensors to propose at a very attractive price this highly innovative product that is also integrating into the same controller the famous Confocal Chromatic technique. The user is then able to choose the most appropriate technique depending on the application, leading to outstanding measurement possibilities.
simple scribe and break, hole drilling, edge isolation and cutting. Ribbon silicon cutting with a pulsed laser is a key application where a multi-pass technique is adopted to give full depth cutting. Pulsed fiber lasers are a natural choice for providing a flexible tool capable of marking a multitude of materials.
The laser provides multifunctional capabilities that can be used for more than one application.
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SPI‘s current pulsed lasers range from 10–40W, reaching up to 1.25mJ of pulse energy and up to 20kW peak power, with 10- 200ns pulse widths and 0-500kHz operation, makes the SPI pulsed fiber laser the perfect solution for this rapidly developing manufacturing sector.
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