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Printed Circuit Board Assembly & PCB Design Forum

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Earl Moon

#11749

A few more things | 25 April, 1999

No this message isn't about my triumphant return. It's not even about that lady I wanted to run away with to Mehico (who were you again). It's about progress and some of you might be interested, or not.

1) For DEKheads, I submit we had two of Britain's finest (Mike and Kevin) over for a few days. They did miraculous things with our 265GSX'x with FPA. They installed a new rising table with fine pitch pins that were almost totally redisgned to prevent the massive pin breakage we experienced.

For those of you not knowing, the DEK fine pitch AutoFlex (FPA) system allows about 1000 pins to be programmed to offer bottom side board support. Well, there are 29000 parts in one of these tables and we excercise them about 15 times a day for new setups. This provides the opportunity for pin breakage as the pins were of the wrong metal, chrome plated, and with now radius leading to the threads needed to screw the little bastards into their end caps.

Anyway, we were breaking about 2 pins a week at a cost of about 4 hours downtime for replacement (the equivalent of about 20000 placements in our world). These folks came up with new metallurgy, no plating, an adequate radius, reduced pin activation pressure, and new software to drive the whole thing. The short of it (as say the Btitish) is we are now operating pin break free - hopefully beyond when I go back in tomorrow.

2) For SRT'rs, I finally got the damn thing to work on our 16 layer nightmare board. Thanks to PHD, and others, I was able to shield adjacent devices and raise the heating nozzle off the board about .100". Now I can remove, replace, and reflow parts all without fear of damaging or causing excessive intermetallic formations on parts within .200" of the escaping hot air.

Previously, we had to use the Big BTU (big thermal unit) to reflow all parts on both sides of these boards. What a time consuming, but very effective drag.

3) Finally, we are getting closer to using Alpha's "Tetra" foils and stencil printing frameless stuff. We are doing the shake to break stuff now. This system looks great so far and will offer opportunities as re-fitting all our old Fuji frames (edge justified, left over from yesterday, needing to run panels on the conveyor length-wise stuff) to DEK center justified frames. This means our 18" wide panels now become 18" long panels and we can reduce the rail adjustment accordingly. This means no more boards sagging below board stops (when the pressure is too low, etc.) and fewer programming efforts for adequate bottom side board support.

4) Still having ongoing problems with vias in pads. Those RF engineering types just won't look at options as plated over holes and micro-vias (don't blame them as they aren't yet totally reliable), or neck downs.

That's about it, and on it goes.

Earl Moon

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