In a message dated 1/27/99 8:41:13 PM Pacific Standard Time, [log in to unmask]
writes:

 > Here is one for the Design and Assembly folks.
 > We are a high volume OEM of consumer electronics.
 > My Assembly has converted to a No-Clean process.
 > What are the differences that I should be concerned with at the design
 > level?
 > Should I have concerns about or modify any designs left over from the
 > Aqueous days?
 > Thanks for the help

 > FNK
 >
 >
 > Frank N Kimmey, C.I.D.
 > EM Designer
 > C & K Systems, Inc.
 > 916-353-5366
 > [log in to unmask]

 Hi Frank!

    I was with a memory company when we converted from water soluble to no-
clean, and there were a few suprises for the finance department that weren't
realized when the decision was initially made to change processes.

    One of he biggest expenses was stencils. We had over 400 different part
numbers of SIMM's, DIMM's, Cache Modules, & PCMCIA products...you wouldn't
believe the number of stencils we had. Well, they were all made when we washed
everything. Stencil apertures for all passive components were 1 to 1 except
for the industry standard etch factor compensation...and most of you can guess
what happened when we used those stencils with no clean. You got it! Squeeze
ball city! Not a big deal when the boards get a bath before they leave the
factory, because they normally always wash off...(that's why everybody lives
with this process defect in a cleaning environment) but a very big deal when
you're no-clean. Every last one of the stencils needed to be replaced...and at
a average of $400 a pop at 400 stencils...(that's ummmm...lessee,...zero times
zero equals zero, and then 4 times...oops wait, gotta take off my shoes
now..)....uhhhh...just TRUST ME, it's a whole lotta moola! (GRIN)

    Another thing that drove the costs up was the fact that we couldn't buy
material the way we had in the past. Couldn't give those 100,000 board orders
to fab vendors anymore to keep the prices down, and let the PCB's languish
around on the stockroom shelves oxidizing and expect to solder em' with no-
clean. Same thing went for the DRAM. Used to buy from anybody and everybody,
but had to be a little more selective when the process changed.

    One thing you might do in your designs, if you haven't already, is to
implement some sort of SIR comb pattern that you put on every one of your
designs. It's up to you where you want it to be. It could be one like what's
on IPC's B-24 board or as simple as two unmasked traces next to each other.
What we were doing since practically every one of the products we build was
panelized, we put them on the coupons, or skirts of the panel. They went along
in the process just like the SIMM's did so we would test them. That way when
we wanted to to a SIR test we wouldn't tie up any shipable product.

     Another thing that I think that's pretty important, is to standardize on
a surface finish and mask type that you use on all your fabs. We used o get
boards from about 5 or 6 main vendors, and to try and get your arms around all
of them so they're all giving you the same thing can be a bear, but it really
makes things easier and more predictable on the production floor.

Good Luck!

-Steve Gregory-

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