Homebrew PCBs

>I get a bunch of nice spherical silver solder balls sitting in a
>field of dried out grey mud 

Copper mass is such that there is insufficient heat to raise 
copper/paste temperature to proper range in a reasonable timeframe. 
Instead, the flux dries out well ahead of solder melting and starts to 
do more harm than good. If this is a test using an unetched piece of 
board then it may never work in that oven.

You could try bringing the oven to maximum temperature for a while 
before placing the pasted board inside but even that may not work if 
there is too much copper. I use a hot air gun most of the time and an 
oven when there isn't too much copper to tin.

--- In Homebrew_PCBs@yahoogroups.com, "Mark Merclean" <mamhouse@...> 
wrote:
>