In a message dated 97-05-31 00:47:02 EDT, you write:

>Sometime ago, a PCB manufacturer gave a presentation and talked about "ED" 
>  technology while unfortunately I was not present. People in the 
>  presentation are still not clear what ED is and asked for my help. I am
not
>
>  a PCB expert either. I tried to find something on the net w/o luck. 
>  
>  Is ED a new resist technology? What are the conventional technologies? 
>  Could someone on the net offer some insights or some references?
>  

Yuan Li:

I suspect strongly that the presenter was referring to Electrophoretic
Deposition, a relatively new technology in application of photoresist.  Most
PCB manufacturers use "dryfilm" photoresist, where the photoresist is
supplied as a film, wrapped up on a roll.  In ED, the photoresist is
literally electroplated directly from a solution, on to the Copper foil, in
theory, giving a very uniform coating, that is very thin, thus allowing very
fine line/space, at least as compared to dryfilm photoresist.

This technology is not very common, and there have been many attempts at
making it successful, which have failed.   The technology sounds extremely
promising, but it will take some very sound engineering to make it
successful.

I hope this is insightful.

Rudy Sedlak
RD Chemical Company

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