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At the recent NEPCON China event in Shanghai, I had the opportunity to talk to Thomas Bredin, area sales manager at Mycronic, about solder paste printing, and how the jet printers are getting up to speed with the challenges such as tighter tolerances and finer lines and pitches.
Stephen Las Marias: What are the biggest challenges that your customers face when it comes to soldering?
Thomas Bredin: In our experience, if you don’t have a jet printer, you need to compromise on the stencil thickness, or you need to go into step stencil or 3D stencil. It becomes very challenging to have the right volume for every single solder joint. The challenge is, of course, yield; you need a lot of inspection machines to verify that you do have the right volume of the solder paste after screen printing with the different aperture sizes.
We think that when you have the freedom to use a jet printer, every solder joint will be perfect; but the machine is not always fast enough to keep up with the takt time of the line. Obviously, more and more customers are using the jet printer as a complement to screen printing to do add-on jetting. So you have a two-prong approach to achieve the perfect volume.
Las Marias: What about the trend towards miniaturization? Nowadays, boards are getting smaller, with tighter tolerances and narrower lines and pitches. What’s your comment on that?
Bredin: In parallel to that, when you see smaller boards obviously you need to have a grid of boards actually. It’s not fast enough to do one at a time. With many screen printing processes, you have a problem with the stretch of the board, and then you need it to align the stencil and so on. It can be very challenging to have the accuracy needed for those small volumes. Again with the jet printer, you can do the same as every pick and placer. You can either locate the global producer mark on the panel or go down to individual PCBs to have the perfect accuracy, even though the individual boards may be shifted or stretched.
We also see you need to shoot smaller and smaller volumes. Smaller and smaller volumes need a finer pitch, and it’s an ongoing process in our R&D team to make sure that our ejector technology keeps up to pace with the customer needs. It is a challenge. To get those small volumes of solder paste is not easy.
Editor's Note: This article originally appeared in the June 2016 issue of SMT Magazine.