Homebrew PCBs

Hello Neal.

 

I'm assuming that you are asking how clean the lines are after etch (as
opposed to how clean the etchant is after you have etched some boards).  I
you are using the "swish the board around in the solution" method, I cannot
say how the lines will turn out (I have practically no experience with that
method of etching).  I would imagine they would be okay down to a certain
width, but at some point I would think that the "swish" method would produce
ragged, uneven, and/or broken circuits for a number of reasons. poor
chemistry distribution, chemistry out of range (out of specification),
chemistry getting up-under the resist, etc. 

 

Our equipment was applying the chemistry to the board by spray.  If all of
the nozzles were properly clean, and the oscillation system that sprayed the
chemistry was operating correctly (and the chemistry was in specification),
the application of etchant was very evenly applied to the board(s).  The
impact of the spray on the board (the impingement) speeds up the etching
process considerably.  When using a high quality photo-resist and everything
was working properly (including artwork, imaging, applying the resist, and
developing), we were able to achieve line spaces and widths as small as 5 to
3 mil's with typically nice straight lines, and the industry is currently
trying to get even tighter tolerances.  I once read that in another 8 to 10
years, the industry wants to consistently achieve 1 mil lines and spaces.
<whew>

 

I'm curious as to whether anyone has built their own home spray etcher (a
small bench-top machine)?  It would be fairly easy (albeit the time and
components required).

 

Cheers to you too!  I'm guessing you're in the U.K.  I'll be visiting the
U.K. in about two months.  Although I've made several business trips over
there, this will be my first vacation (holiday).  I'm looking forward to it!

 

Marty

 

-----Original Message-----
From: Neil [mailto:cobra_neil@...] 
Sent: Thursday, May 22, 2003 12:21 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Etchant options?

 

Hi Marty,

Interesting info.  Thanks.

Would you have any info relating to how clean the final etch is, and what 
minimum traces can be obtained by each of the options you mentioned.  I've 
traditionally used FeCl, but just picked up some Ammonium Persulphate (MG 
Brand) but haven't tried it yet.  Also, the ammonium fumes may be a problem 
so I'm not trying to get as much info as possible before I actually try it.

Cheers,
-Neil.
 



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