MICROMACHINING


MAKING A CLEAN BREAK


Greg Blackman looks at the state of adoption of ultrashort pulse lasers in consumer electronics production


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aser makers are receiving orders and increased interest in ultrashort pulse laser technology from consumer electronics manufacturers for cutting brittle materials


like glass and sapphire. Cutting glass for mobile phone screens with ultrafast lasers has been recognised has having ‘big potential’, according to Jochen Deile, a product line manager at Coherent, but adoption has been slow up until this point. Now, however, Deile commented that Coherent has received its first significant orders for production equipment to cut glass for the next generation of consumer electronic products, adding that the technology is currently being implemented in production. Other ultrafast laser suppliers report a similar


trend of greater adoption of laser technology in the consumer electronics sector. French ultrashort pulse laser maker Amplitude Systèmes is working with mobile phone manufacturers, according to the company’s vice president of sales, Vincent Rouffiange, and over the past three years has been developing processes for machining transparent materials such as glass or sapphire with femtosecond laser pulses. Dr Herman Chui, senior director of product marketing at Spectra-Physics Lasers, now owned by MKS Instruments, commented that some ultrafast laser processes are already in use in consumer electronics production, but went on to say that adoption is not broad-based yet. ‘Tere’s a lot more potential for using ultrafast lasers in consumer electronics,’ he said.


Te potential for ultrashort pulse lasers – those operating at picosecond or femtosecond pulse


www.lasersystemseurope.com | @lasersystemsmag Mobile phone screens are largely cut with mechanical tools, but ultrafast lasers offer an alternative


durations – to replace mechanical tools for cutting glass in consumer electronics is certainly there. At such short pulse durations, the energy put into the part with each pulse of laser light is huge; ultrafast lasers are capable of a process known as cold ablation, whereby material is ablated without putting any heat into the surrounding part, all because of the properties of the laser pulses. Machining glass with an ultrashort pulse laser is


for using a laser is that you can eliminate process steps


The main reason


slightly different to machining metal, and there are different ways of creating a cut in glass with a laser. One of these is filamentation, which Deile described as a ‘mature process’ and one that is being ‘adopted right now’ by consumer electronics manufacturers. Here the ultrashort pulses don’t ablate the glass, but modify it to create a filament inside the glass that serves


as a weak point to make the break. ‘Tere are various laser cutting processes


employed, but in terms of cutting screen glass, we think laser filamentation is the best process to do that,’ Deile said. Coherent-Rofin recommends using a picosecond laser, and offers its SmartCleave lasers for glass filamentation.


Mechanical methods, using a diamond-tipped


saw to scribe and then snap the glass, followed by grinding and polishing to get the surface finish, are the predominant means of cutting screen glass for consumer electronics. However, these are limited to cutting in straight lines and they also generate glass particles, which is particularly damaging for clean-room environments in electronics production. ‘Te main reason for using a laser is that you can


eliminate process steps and therefore save money,’ explained Chui, referring to the laser’s ability to produce a very good finish, meaning that post-processing steps like grinding and polishing are not required to some extent. Other advantages of using a laser over


mechanical machining are that the laser gives greater flexibility, noted Deile. A laser isn’t limited to cutting in straight lines and can cut more complex geometries, a big plus for cutting the curved screens found on the latest models from a number of phone providers. ‘A laser process can bring a lot of benefits to cutting shaped glass,’ he said. Laser filamentation is also flexible in terms of the material mix, Deile added. Te laser can cut many


ISSUE 36 • AUTUMN 2017 LASER SYSTEMS EUROPE 19


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