Tag Archives: SMTAI

Tighter Ratio Rules Ahead?

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The long-held area ratio rule (the ratio of aperture size and stencil foil thickness) of 0.66 is under attack from all sides, it seems.

Writing this month in CIRCUITS ASSEMBLY, columnist Clive Ashmore explains that improvements to the shear thinning capability of the print stroke can reduce the area ratio to 0.40. This is an important development because tighter ratios offer greater latitude in stencil design. The rule today is that, since a larger component generally requires more paste volume than a smaller one, one or the other suffers: Optimize for the larger part and print quality suffers on the small aperture; optimize for the smaller ones and the larger parts are starved of paste. With the lower ratio however, as Ashmore notes, 0.3 mm CSPs could be placed beside large tantalum capacitors without penalizing one or the other.

Next week at SMTAI in Orlando, Rockwell’s Kevin Liticker will present his work evaluating several stencil technologies including “PhD,” fine grain stainless and nickel stencil, and aperture forming methods like pulsed YAG laser, fiber optic laser (with and without electropolish) and electroform as they relate to paste transfer efficiencies for small apertures. I’m not going to give away the store, but he found some evidence that the release characteristics of fine grain material may be superior as apertures shrink.

I strongly suggest checking out both engineers’ work.

Trade (No) Shows

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SMTAI is over and done.  It was, in my opinion, a disappointment. While several companies remain on travel lockdown, the location — San Diego — was central to large numbers of designers and assemblers, precious few of whom bothered to make the (short) drive.

I don’t have the numbers from the SMTA yet, but my sense is the attendance for the technical conference was pretty good. But there was very little traffic on the exhibition floor, a result that mirrored IPC Midwest a few weeks earlier.

We can blame the economy. We can blame the layoffs. We can blame a lot of things. But the industry seers — also known as the media — have been saying for years there are too many shows. With Electronics New England, Electronics West, SMTA Atlanta, the myriad Design2Part shows, IPC Apex, Assembly Technology Expo, IPC Midwest, PCB West, and SMTAI, among many others, the regionalization — and bastardization — is effectively complete. There is simply no reason for a potential attendee to get excited about an event, because when you are practically showered with opportunities, the impact is dramatically lessened. (As an aside, none of this should be laid at the feet of the SMTA staff. They worked their hearts out to put on a top-notch technical conference and to this observer’s eye everything was beautifully executed. They deserved better.)

The show producers of these events are going to have to look hard at their bank accounts and reconsider their missions. While I don’t expect the for-profit companies (of which Circuits Assembly’s parent company, UP Media Group, is one) to change their approach, it’s high time the trade associations get together and get an agreement done that puts some sanity back into the trade show calendar.

Put the egos and greed aside, and get it done.