The Good Gets Even Better: Flex PCB Laser Etching

Posted by on May 5th, 2016

Flexibility is a good thing if you’re an Olympic gymnast or Cirque du Soleil performer – and it’s essential for PCB designers and manufacturers whose prototypes and end products demand precision etching on flex PCB materials. For the past 40 years, standard mechanical PCB milling systems have been the tools of choice for straightforward milling operations, and in some cases, they’ve been great performers for flex PCB etching as well. LPKF’s top-performing ProtoMat mechanical PCB milling systems, for example, feature faster spindle speeds, low runout and high resolution for working with substrates as thin as 5 mil for single-sided designs and traces, and spacing as small as 4 mil. All good stuff, so how could it get even better? Laser.

Laser for flex PCB etching, drilling and cutting: the unsung hero

Today, laser machines have taken flex PCB prototyping to a higher level to give manufacturers more precision and cost savings. The high positional accuracy and depth of cut calibration possible with lasers can handle the most challenging applications on some of the most difficult flex materials. In addition, because PCB designers can perform laser etching with a compact, in-house laser, they avoid the high cost and turn-around time required when outsourcing to a board house. Surprisingly, though, lasers are the unsung hero of the PCB world. Laser removal of metal from flex materials is a very unique process, but not many manufacturers have tried it. Here are some good reasons why they should:

  • With a 20um diameter focused laser beam, even smaller traces and spacing are possible depending on the material.
  • Au removal and additional metal ablation can also be achieved on various PET materials.
  • Microvia drilling of flex polyimide materials can also be completed with the same laser creating 50um (2 mil) diameter vias.
  • Polyimide stencil cutting is also a standard capability of the LPKF UV laser models.
  • Partial laser engraving of polyimide is also possible with the laser power, travel speed and pulse frequency adjustable as laser tool settings.

Our ProtoLaser systems play a leading role in flex PCB laser etching at LPKF. We’ve developed a hatch and controlled laser delamination process that enables our ProtoLaser to create double sided designs by removing copper to achieve ~3 mil (75um) traces on DuPontT Pyralux® TK 127512R fluoropolymer/polyimide composite and Pyralux® AP 8565R polyimide materials. Copper ablation is also possible on DuPontT Pyralux® TK or with AKAFLEX KCL 9-25 from the Krempel Group since laser energy is absorbed at the adhesive layer.

The bottom line is that flex PCB materials and circuits are playing an increasingly more important role in today’s PCB industry. And that demands more precision and accuracy in etching highly complex flex boards. While mechanical milling machines still have their place, the laser systems give you the added advantages of precise energy control, minimal stress, arbitrary contour cuts, and more accurate, dynamic positioning for flex PCB etching. Try it. It might be just what your business needs to get to the next level.

 

Questions about laser machines and flex PCB etching? Visit www.lpkfusa.com to contact a LPKF sales engineer to discuss your flex PCB manufacturing challenges.