Homebrew PCBs

I know spin coating has been used commercially but it always bothered me
since I do not understand how it can be a uniform coating.  Basically there
is zero centrifugal force in the center and lots at the edges.  How can that
create a uniform coating?

 

Decades ago I used to coat PCBs by SLOWLY withdrawing them from a skinny
rectangular tank which left a uniform coating except the bottom edge.
Placing the PCB still vertically on a tissue paper drained off the excess at
the edge.

Bertho

 

From: James    Sent: Sunday, April 07, 2013 00:15



On 07/04/13 15:58, Todd F. Carney / K7TFC wrote:
> Ben,
>
> I think he was referring to the capacity of the spin machine he showed in
> the photos. I used to use spin coating, and there's no reason it can't be
> bigger.

How fast does it have to spin? The velocity of the outside edge of the 
board would be getting quite high I imagine as you increased the board 
size.



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