With a room full of Uv / Co2 lasers juxtaposed to my office, here's a few pennies of my thoughts: Co2 lasers do excel in the cutting of specific materials. They are used to cut steel, hobby stuff such as model airplane balsa wood parts, plastics, glass, etc... However, with pcb's my choice would be to use Uv at a low power. Sometimes I'm called upon to cut board features with the Uv laser. The Uv will get me through the metals and the dielectric, versus only dielectric with the Co2, at lower power levels. Steel lasers may use upward of 150W+, while pcb lasers are usually system limited to 3 - 20 or so watts. Large steel cutting lasers may feed material without a bed or platen, while a pcb laser drill / router will have a vacuum table to hold the board. Throwing high power pulses on your platen can damage work-piece board surfaces due to reflection, and can damage the platen itself. Therefore lower power pulses are used. With a 15 - 20um Uv beam and a mere .5 - 1 watt of power, the cut is so small you need to use a scope to see it. As the laminates are a woven epoxy glass, the epoxy, with a higher absorption rate will ablate before the glass fiber bundles or any metals. Yes there will be some charring, but less with Uv. I would cut through the epoxy and a good portion of the glass bundles, similar to a score operation. The board feature would then just need a bend to break off. My choice of lasers depend on the difference of material properties, mostly due to the fact that the Uv laser works more in a bond breakage type mechanism, versus the melting / burning ablation mechanism of a Co2 laser. Consideration is also given to beam collimation / shaping and type for the application. Experimenting with different lasers on a particular material is the only way to prove the results. I've cut tempered glass & plastics on a Co2 with clean results. Some plastics produce a frosted appearance on the cut edge, while others will produce a melted / mirror like surface. Most of the charring that occurs on board material is the ablation of the epoxies, as the glass cloth cuts fairly clean. Under a scope you would see the 'ball' end lenses created on the tips of the cut glass fibers with a Co2, versus a 'sheared' appearance with the Uv. Dave Simonik CNC Laser / Mechanical Tech. Sanmina SCI Corp. Owego NY Division -----Original Message----- From: Atkinson, Neil [mailto:[log in to unmask]] Sent: Wednesday, April 27, 2005 4:49 AM To: [log in to unmask] Subject: Re: Laser Cut PCBs Thanks Mike, Actually we are looking at CO2 laser on FR1 material. The laminate discolours and leaves a small amount of 'soot' on the cut edge. Neil -----Original Message----- From: Mike Fenner [mailto:[log in to unmask]] Sent: 27 April 2005 09:43 To: 'TechNet E-Mail Forum'; 'Atkinson, Neil' Subject: RE: [TN] Laser Cut PCBs I've been out of this a while but so far as I recall Assuming a CO2 laser and FR4, theoretically if it is correctly tuned/focused it should give a big enough instant enough whack that the laminate is vaporised before it burns. In practice you are likely to get a little discoloration (no charring), you can reduce this by going for a perforation rather than a continuous cut as this reduces rate of heat input leading to local overheating. If you are looking at the high frequency funny stuff laminates with random weaves, then it is possible to make continuous cuts on some of these OK, [but there are too many types to remember now which specifically]. Regards Mike Fenner Indium Corporation T: + 44 1908 580 400 M: + 44 7810 526 317 F: + 44 1908 580 411 E: [log in to unmask] W: www.indium.com Pb-free: www.Pb-Free.com -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Atkinson, Neil Sent: Tuesday, April 26, 2005 6:10 PM To: [log in to unmask] Subject: [TN] Laser Cut PCBs We are looking to use lasers to de-panel assembled PCBs, the initial results look very good apart from a slight burning (obviously) on the edge of the laminate. The burn is just on the surface in most cases but can discolour the laminate up to 1/4 mm into the PCB in the worst case. Does anyone have experience of this? What reliability issues can you foresee? By the way - Petrol (Gas) is currently almost $7 a gallon in the UK! Many thanks, Neil ::::::::::::::::::::::::::: This email, its content and any files transmitted with it are intended solely for the addressee(s) and may be legally privileged and/or confidential. 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