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

[Jon Elson]

On 03/19/2015 09:29 AM, Paul Koning wrote:
> I used to think of BGA as not possible for home 
> construction. Then I read a nice article — 
> https://www.beta-estore.com/download/rk/RK-10001_76.pdf — 
> about reflow soldering using what amounts to a 
> toaster-oven with a temperature control added, which 
> apparently does the job just fine. There are some details 
> to get right, which the article explains.
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 compromise.

Jon