Homebrew PCBs

Hi,

tried it today, with mixed results (but definitely worthwhile).

A few things i noticed:

There seem to be two "stages" of tinning.
Where the heat of the heatgun was greatest, just below the center of the  
nozzle, the reflow was more complete. What i see there is s rough surface.  
Like the paste was much coarser as it actually is. On the other hand in  
areas with less heat it appears that the board is still tinned nicely, but  
with a shiny, uniform, and thinner. I wonder how the paste can tin the  
board without actually reflowing...

Also, i could not get the paste to reflow to a silver appearance before  
burning the board. I had expected it to go shiny silver at some stage,  
like SMD paste, but it didn't. It just stays the same dull grey, but after  
wiping the board off underneath is a shiny silver tinning?
The packaging says one should see when it reflows.

What about silkscreen? will it work over a board tinned that way?
Do you drill before or after tinning?


Note that i used a old solder paste with lead content, which gives a less  
silvery appearance anyway. I am planning to get tin only paste, also  
because it is a slightly messy procedure and i am not fond of "loose" lead  
particles around and in the water.

I will make several sample pieces and heat them with different temperature  
settings, to find out about the strange reflow...

ST