Yahoo Groups archive

MOTM

Index last updated: 2026-04-28 23:35 UTC

Thread

SMT issue(s)

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

Move to quarantaine

This moves the raw source file on disk only. The archive index is not changed automatically, so you still need to run a manual refresh afterward.