SMT issue(s)
2003-09-12 by Paul Schreiber
The 2 main problems with going all SMT, all assembled route for MOTM: a) you HAVE to use specific reel sizes for SMT "loaders" if you want the machine to place the parts. The problem is: these reels hold *5000* caps/resistors or *2500* diodes/transistors/etc. Look at any kit BOM. Look are the number of *different* resistor values. See the problem? The 5% resistors are cheap, a reel is like $22. However, caps are like $280 a reel! So, I'd have to spend several $$$$ of dollars buying 40-60 reels of stuff. AND THEN.....about 10% of the caps/resistors are hand placed anyway, because of the precision 0.1% stuff (a reel of these are like $13000!!!!) b) the solder paste is applied through a precision laser-cut stainless steel screen. This screen is unique to each board. These screens are about $500 EACH (1 per module). AND....let's say I build 150 EGs. Then I run out. I have to run at *least* 100 more (and pay for ALL 100 in 30 days, even if it takes 4 months to sell them all). You can't call up and get 20 more of a SMT run: it's in batches of *100 at a time*. The screens have to be cleaned and set up in the machine (called "registration"). The fee for that: $375. Oh...then, the operator has to unload the parts reels for the prior job, and load in MY reels (in the *correct order*). This charged $5/reel. So, a SMT run for 1 board, before you place 1 part on it, can be easily a $800 "set up charge". Running 10,000 motherboards? big deal! Running 100 MOTM....$8/board for 'nothing'. Well, the conclusion is: there is not much I can do except plow ahead. Paul S. 2 oxen and 100 acres to plow