Hi Bob-

You forgot to say you want it real cheap too!

Seriously, the big fly in the ointment is the fast changeover and the cost. 
Otherwise, there are new and used high precision small printers (such as 
MPM--you'd have to add board mounting blocks to the stage) available. Setting 
up any printer takes a while. Solder paste is inherently filthy, and without 
careful attention to detail "gums up the works", reducing repeatability.

Being small saves you very little because all of the manufacturing cost goes 
into getting the precision you need anyway. So there's virtually no market for 
a small machine that does high precision--Would you pay a discount of only 15% 
if the stencil size you could use went from 20"x20" down to 12"x12"? Probably 
you would look at potential growth and resale value, and conclude that it's 
worth it to buy the 20"x20".

As I'm sure you've seen, there are manual systems set up for small prototype 
runs where the squeegee is either held manually or just driven manually. These 
can be frustrating to use because the alignment mechanisms are cheesy and, if 
you go that route, you'll probably figure out some enhancement which need to 
be made to make it more repeatable/convenient. As delivered, they really 
aren't a whole lot better than just hooking a stencil holder to some door 
hinges and taping the boards down!

"Fast changeover" suggests no stencil at all--use a "jetter" to fire little 
globs of paste at the board. We're investigating that process right now 
through a contract assembly house that has a jetter on their P&P machine. I'm 
skeptical on the 0201s, and the prices of these things are probably 
considerably beyond your budget. When considering this option, you need to 
realize that purging the solder paste from the capillaries and valves is 
probably not much fun, so I'd suspect that once you get one of these things 
running decently, you really want to keep throughput so the paste doesn't get 
old.

Wayne

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Wettermann
Sent: Tuesday, March 03, 2015 9:07 AM
To: [log in to unmask]
Subject: [TN] Proto Printer Recommendations

We are in need of a small SMT printer able to double sided boards with an 
emphasis on fast changeover and  the ability to have board supports.

Our typical lot size is 1-20 pieces of rigid boards with technologies down to 
0.5mm pitch and 0201's.

Thanks!
--
Bob Wettermann


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