Laminar flow is not good for etching. Turbulence is desirable to enhance the exchange of spent and fresh etchant at the surface of the board. In pure laminar flow, there is no exchange between layers of fluid; the streamlines don't interact except through friction and there is no flow perpendicular to the surface. For etching to work, the etchant near the surface must be replaced by fresh solution from the bulk, so agitation and turbulence are used.
HTH,
Donald.
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----- Original Message -----
> From: "Rick Sparber" <rgsparber@...>
> To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
> Sent: Friday, November 23, 2012 7:15:53 AM
> Subject: [Homebrew_PCBs] first step into convection etching
> Although I have done analog circuit design for 50 years, I'm a
> relative
> newbie when it comes to circuit board etching. Furthermore, my last
> chemistry class was in 1967. Here is my first step into convection
> etching.
>
>
>
> http://rick.sparber.org/electronics/ce.pdf
>
>
>
> How do I improve this process? I understand that bubbling air into the
> acid
> will speed it up but won't that spoil the laminar flow?
>
>
>
> Thanks in advance,
>
>
>
> Rick
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
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