Try etching it face up...instead of face down. Etches much cleaner. brush it lightly with a nylon (white brisel ) paint brush after about 15 minutes and you should be about there.
Terry
________________________________
From: Donald H Locker <
dhlocker@...>
To: Homebrew PCBs <
Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, March 4, 2012 9:53 PM
Subject: Re: [Homebrew_PCBs] Etching problem - Help please
I'd say a process problem. Agitate more often and more vigourously. The stripes are from the glass beneath the copper - the copper I believe is slightly thinner over the glass strands so etches faster than the slightly thicker copper surrounding it.
Try continuous agitation (rocking the tray) and warm FeCl (it will etch faster than 16 min) and see what happens.
HTH,
Donald.
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----- Original Message -----
> From: "Pete" <pete@...>
> To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
> Sent: Sunday, March 4, 2012 5:45:40 PM
> Subject: [Homebrew_PCBs] Etching problem - Help please
> Hi,
>
> I am trying to etch a small PCB and finding it etches unevenly leaving
> a small area of copper which is stubborn to remove. Just leaving in
> the etchant for longer starts to undermine the tracks that etched ok.
>
> Here's what I do:
>
> 1. Print the track layout on inkjet printer using transparency film.
>
> 2. Lay the film ink side down onto a 3" x 2" single sided photo resist
> coated copper clad board (cut from a Maplin Size 4 ref KU14)
>
> 3. Expose in a home made LED Light box for 4 minutes
>
> 4. Develop in Universal Developer (PBD2) Sodium Metasilicate for 1
> minute.
>
> 5. Etch in Ferric Chloride track side down for 16 mins, agitating
> every minute or so.
>
> The result is most of the copper dissolves after 10 mins then it
> leaves a small area which refuses to disappear after waiting a further
> 5 minutes.
>
> A photo of the etched board is here
>
> https://picasaweb.google.com/109391378120539635298
>
> On close inspection of the board the unetched copper is left as
> stripes. So I am wondering if this is a board problem or the process.
>
> Any help is appreciated.
>
> Thanks
> Pete
>
>
>
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and
> Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>
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