Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Hello all,

OK, I take up electronics as a hobby. Hit roadblocks, find this yahoo
group. Read like crazy and figure out how to make PCB's using the
laser toner method. Great advice, get process down to 99% success
rate.

Then I see a picture of a great PCB tinning job here - I think from
Derek Hawkins. So I read, order some tinning paste (McMaster Carr
#7774A11, page 3286 in online catalog), get a toaster oven, and
voila, all should be set. But can't seem to do this one, and need
advice from the experts in this group again.

I bring the oven up to ~440F degrees (according to Mcmaster, the
melting range is 426-454.) and stabilize it (as best a toaster oven
can). Bought a thermometer to put in the oven to check temp. Clean
the PCB with acetone before coating to be sure no junk on it. Coat
with ever so slightly water diluted paste, and put in the oven.
Results:

1) I get a bunch of nice spherical silver solder balls sitting in a
field of dried out grey mud (ie, the solder paste without the solder
balls, dried out and coating the pcb)

I figure I don't have the heat high enough, but when I turn it up it
just "burns" the paste.

Can anyone offer some suggestions as to why I get dried out paste
with solder balls growing in it?

Thanks,
M

PS - I get the smae result if I dont dilute with water and just use
right out of the jar.