4 MB memory unibus/qbus card (was Qbus split I&D?)

John Wilson wilson at dbit.com
Thu Mar 19 15:59:17 CDT 2015

On Thu, Mar 19, 2015 at 11:30:48AM -0500, Jon Elson wrote:
>I reflow boards in a modified toaster oven, not too different from the one in
>the picture.  But, it did NOT work well when I first tried it.  I just hung
>the thermocouple in the air, and the boards were burnt to a crisp!  The IR
>from the heating elements is absorbed VERY well by the boards, and they heat
>much faster than the air. So, my trick is to poke a
>very tiny thermocouple into a plated through-hole in the board, and then it
>reads the actual temperature of the board.  I still have some problems with
>hotter and cooler areas of the oven, but you can usually find a good

Same experience here.  Many fried boards until I tried touching the
(bare -- not sheathed) thermocouple to the board (doesn't have to be in a
PTH, although that might stop it from occasionally twanging and sweeping
components off).  I've only minimally tried BGAs (just liquid flux w/no
solder paste at all seemed to be the answer there) but I've had fantastic
luck with QFPs, SOICs, TSSOPs, and and all kinds of SMT passive components.
www.oshstencils.com makes it just too easy.

John Wilson
D Bit

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