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Re: Etching woes: Press-n-Peel, Laminator, Etch Tank + Sodium Persulphate

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  • phil.quinton@ymail.com
    Todd, Thank you for the advice. If you use a tray for etching, how do you keep the temperature up for the sodium persulphate? Or is it just a case of getting
    Message 1 of 8 , Feb 19, 2013
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      Todd,

      Thank you for the advice.

      If you use a tray for etching, how do you keep the temperature up for the sodium persulphate?

      Or is it just a case of getting the water warm before you mix in the etchant?

      It's possible that the agitator is too aggressive, especially as the etch time is taking so long.

      Can there be a difference in the quality of the sodium persulphate? The current batch is from a difference source to the very first etching.

      Thanks again,
      Phil.

      --- In Homebrew_PCBs@yahoogroups.com, "Todd F. Carney" <k7tfc@...> wrote:
      >
      > Either ammonium persulfate or sodium persulfate is used by commercial pcb
      > manufacturers. They do not use ferric chloride, not for decades. Only
      > hobbyists use the stuff. I'm using a peroxide-muriatic acid-sodium chloride
      > etchant. It's very cheap, and the chemicals are available either in a drug
      > store or at places such as Home Depot (for the acid). I use it "one-shot."
      > I use just enough to do the board I'm etching and then toss it away. It's
      > that cheap. This way, It works the same way--etch times, etc.--every time I
      > use it.
      >
      > 73,
      >
      > Todd
      > ------------------------------------------------------------------------------------
      > K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
      > ------------------------------------------------------------------------------------
      > QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design
      >
      >
      > On Tue, Feb 19, 2013 at 9:12 PM, tda7000 <Tda7000@...> wrote:
      >
      > > **
      > >
      > >
      > >
      > >
      > > I have used the toner transfer method with the laminator described here:
      > > http://ultrakeet.com.au/write-ups/superfuser
      > >
      > > I have not used Press-n-peel blue, just magazine paper. However I have not
      > > had undercutting (that I ever noticed!). I used old Ferric Chloride and
      > > later on the Hydrochloric acid and Hydrogen Peroxide mixture. Both worked
      > > great.
      > >
      > > http://ultrakeet.com.au/write-ups/etchantComparison he describes Ammonium
      > > Persulphate as being much worse than Ferric Chloride. I have never used
      > > Ammonium Persulphate.
      > >
      > > I don't know if it's any different to Sodium Persulphate in terms of
      > > undercutting, but if his article has any truth behind it I would probably
      > > try something else.
      > >
      > >
      > > --- In Homebrew_PCBs@yahoogroups.com, "phil.quinton@" wrote:
      > > >
      > > > Hi,
      > >
      > > First post, hopefully one of many..
      > >
      > > To cut a long
      > > > story short, I'm having problems *after* etching with Sodium
      > > > Persulphate
      > >
      > >
      > >
      > > In short, it appears to be etching *under* the
      > > > toner somehow.
      > >
      > > My guess is that the etch tank is no
      > > > longer getting to the right temperature ( ~ 45 degrees ) and I'm etching
      > > > too long with the agitator on. I'm going to get myself a temperature
      > > > probe to confirm.
      > >
      > > Has anyone had a similar experience ( Etch
      > > > looking fine until the toner is removed )?
      > >
      > > Thanks in
      > > > advance,
      > > Phil.
      > >
      > > >
      > >
      > >
      > >
      >
      >
      > [Non-text portions of this message have been removed]
      >
    • Todd F. Carney
      Phil, I use an muriatic (hydrochloric) acid and peroxide etchant in a tray. I mix the etchant just before use, and since the combination is *exothermic*, it
      Message 2 of 8 , Feb 20, 2013
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        Phil,

        I use an muriatic (hydrochloric) acid and peroxide etchant in a tray. I mix
        the etchant just before use, and since the combination is *exothermic*, it
        heats itself long enough to get the job done. I have used persulfate
        etchants in trays, but the solution does have to be heated. This can be
        done, as you suggest, by mixing the persulfate into *hot* water. I say hot
        because as persulfate goes into solution, there is an *endothermic*
        reaction--it cools down.

        By the time it's fully dissolved it's still warm enough to etch,
        particularly since it is a fresh solution and etching times will therefore
        be short. If you reuse the etchant, you can always heat it carefully in a
        microwave. It will also help to preheat the tray and pcb in hot tap water
        so they don't draw heat from the etchant.

        I suppose it's possible you got some bad persulfate on your second try. I
        haven't used it for some time now, so I don't know good sources. I suspect,
        though, that MG Chemicals would have good quality material.
        http://www.mgchemicals.com/products/prototyping-and-circuit-repair/prototyping/
        .

        73,

        Todd
        ------------------------------------------------------------------------------------
        K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
        ------------------------------------------------------------------------------------
        QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design


        On Tue, Feb 19, 2013 at 11:22 PM, phil.quinton@... <
        phil.quinton@...> wrote:

        > **
        >
        >
        >
        >
        > Todd,
        >
        > Thank you for the advice.
        >
        > If you use a tray for etching, how do you keep the temperature up for the
        > sodium persulphate?
        >
        > Or is it just a case of getting the water warm before you mix in the
        > etchant?
        >
        > It's possible that the agitator is too aggressive, especially as the etch
        > time is taking so long.
        >
        > Can there be a difference in the quality of the sodium persulphate? The
        > current batch is from a difference source to the very first etching.
        >
        > Thanks again,
        > Phil.
        >
        >
        > --- In Homebrew_PCBs@yahoogroups.com, "Todd F. Carney" wrote:
        > >
        > > Either ammonium persulfate or sodium persulfate is used by commercial pcb
        > > manufacturers. They do not use ferric chloride, not for decades. Only
        > > hobbyists use the stuff. I'm using a peroxide-muriatic acid-sodium
        > chloride
        > > etchant. It's very cheap, and the chemicals are available either in a
        > drug
        > > store or at places such as Home Depot (for the acid). I use it
        > "one-shot."
        > > I use just enough to do the board I'm etching and then toss it away. It's
        > > that cheap. This way, It works the same way--etch times, etc.--every
        > time I
        > > use it.
        > >
        > > 73,
        > >
        > > Todd
        > > ----------------------------------------------------------
        > > K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
        > > ----------------------------------------------------------
        > > QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design
        > >
        > >
        > > On Tue, Feb 19, 2013 at 9:12 PM, tda7000 wrote:
        > >
        > > > **
        >
        > > >
        > > >
        > > >
        > > >
        > > > I have used the toner transfer method with the laminator described
        > here:
        > > > http://ultrakeet.com.au/write-ups/superfuser
        > > >
        > > > I have not used Press-n-peel blue, just magazine paper. However I have
        > not
        > > > had undercutting (that I ever noticed!). I used old Ferric Chloride and
        > > > later on the Hydrochloric acid and Hydrogen Peroxide mixture. Both
        > worked
        > > > great.
        > > >
        > > > http://ultrakeet.com.au/write-ups/etchantComparison he describes
        > Ammonium
        > > > Persulphate as being much worse than Ferric Chloride. I have never used
        > > > Ammonium Persulphate.
        > > >
        > > > I don't know if it's any different to Sodium Persulphate in terms of
        > > > undercutting, but if his article has any truth behind it I would
        > probably
        > > > try something else.
        > > >
        > > >
        > > > --- In Homebrew_PCBs@yahoogroups.com, "phil.quinton@" wrote:
        > > > >
        > > > > Hi,
        > > >
        > > > First post, hopefully one of many..
        > > >
        > > > To cut a long
        > > > > story short, I'm having problems *after* etching with Sodium
        > > > > Persulphate
        > > >
        > > >
        > > >
        > > > In short, it appears to be etching *under* the
        >
        > > > > toner somehow.
        > > >
        > > > My guess is that the etch tank is no
        > > > > longer getting to the right temperature ( ~ 45 degrees ) and I'm
        > etching
        > > > > too long with the agitator on. I'm going to get myself a temperature
        > > > > probe to confirm.
        > > >
        > > > Has anyone had a similar experience ( Etch
        > > > > looking fine until the toner is removed )?
        > > >
        > > > Thanks in
        > > > > advance,
        > > > Phil.
        > > >
        > > > >
        > > >
        > > >
        > > >
        > >
        > >
        > > [Non-text portions of this message have been removed]
        > >
        >
        >
        >


        [Non-text portions of this message have been removed]
      • William Whyte
        (excess quoting trimmed by moderator - please trim!) Todd,  What are your ratios, particuly the sodium chloride(salt) ?
        Message 3 of 8 , Feb 20, 2013
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          (excess quoting trimmed by moderator - please trim!)
          Todd,  What are your ratios, particuly the sodium chloride(salt) ?
                                                         Ollie       k0lqk

          --- On Tue, 2/19/13, Todd F. Carney <k7tfc@...> wrote:

          From: Todd F. Carney <k7tfc@...>
          Subject: Re: [Homebrew_PCBs] Re: Etching woes: Press-n-Peel, Laminator, Etch Tank + Sodium Persulphate
          To: Homebrew_PCBs@yahoogroups.com
          Date: Tuesday, February 19, 2013, 11:21 PM

          Either ammonium persulfate or sodium persulfate is used by commercial pcb
          manufacturers. They do not use ferric chloride, not for decades. Only
          hobbyists use the stuff. I'm using a peroxide-muriatic acid-sodium chloride
          etchant. It's very cheap, and the chemicals are available either in a drug
          store or at places such as Home Depot (for the acid). I use it "one-shot."
          I use just enough to do the board I'm etching and then toss it away. It's
          that cheap. This way, It works the same way--etch times, etc.--every time I
          use it.

          73,

          Todd
          ------------------------------------------------------------------------------------
          K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
          ------------------------------------------------------------------------------------
          QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design

          (snip excess by moderator - please trim!)
        • Todd F. Carney
          ... Todd, What are your ratios, particuly the sodium chloride(salt) ? Ollie, I m actually no longer using the salt additive, just the muriatic (hydrochloric)
          Message 4 of 8 , Feb 20, 2013
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            On Wed, Feb 20, 2013 at 4:08 AM, William Whyte <olliewhy@...> wrote:

            > **
            >
            >
            Todd, What are your ratios, particuly the sodium chloride(salt) ?

            Ollie,

            I'm actually no longer using the salt additive, just the muriatic
            (hydrochloric) acid and peroxide. I wish I could find my link, but I think
            my original source used salt as a means of getting more chloride ions into
            depleted etchant without adding more acid. I tried it a few times when I
            was reusing the etchant and it did seem to shorten long etch times. Now
            that I use the etchant one-shot---a small amount that is then discarded---I
            don't need to refresh used etchant.

            My formula for the one-shot version is the typical 1 part ≈35% muriatic
            (hydrochloric) to 2 parts 3% hydrogen peroxide (the drug-store variety). I
            warm it a bit to ≈100°F (38°C), but since I use only about 6oz (170ml) of
            solution in a tray, it cools down fairly quickly. I use the foam trays that
            meat comes packaged with.

            I learned the one-shot method as an industrial photographer. Not reusing
            film (and paper) developer, but using small amounts one-shot, allowed for
            precise control that cannot really be had with reuse/replenishment schemes.
            Precise repeatability is possible with one-shot. It's not with reuse.

            Much of the need for repeatability, in my mind, is that we DIYers use some
            pretty dubious methods of applying etchant resist to our boards--toner
            transfer being the most common, it seems--I use it myself. This means using
            materials that are not optimum for the purpose and applying them with
            make-shift methods: cloths irons, etc. Combined with less-than-thorough
            surface preparation of the copper clad, all this means our resist patterns
            are fragile and cannot withstand long etch times with repeatable results.
            It's not just that the resists are probably not-all-that chemically
            resistant, but that their mechanical bond with the copper is weak and
            uneven. Flaking of the resist, or undercutting of it in long etch times, is
            an ongoing problem for many of us. Fast etch times and
            repeatably-predictable results can minimize these problems. Both point to
            one-shot etching.

            Now in my online poking around in the last few days on these issues, I am
            now persuaded that I need to be much-more careful in the disposal of my
            etchant--especially since I'm tossing out several ounces at a time for each
            board. To be perfectly honest, I used to just dump the stuff down the drain
            with plenty of running water. Bad news! So what I'm going to try is to dump
            it into a five-gallon bucket filled about 3/4 full of wood shavings. I have
            a whole bale of the stuff left from when we had hamsters (a rant for
            another occasion). Saw dust or even shredded paper might work just as well.
            I'll dump the spent etchant into the bucket, maybe stir the shavings around
            a bit (maybe not), and then keep the bucket open and outside (not
            inside!!!) but out of the rain. Before long, each dumping will dry in the
            bucket, sequestered (oh that word!) in the wood or paper fibers. I guess I
            should put a warning sign on the bucket. At some point I'll have to
            double-bag the shavings before tossing them in the land-fill garbage, but
            as I'm thinking now it might take many years before that will be necessary.
            It may never be necessary in my lifetime, so I'll have to leave disposal
            instructions in my will (wink wink).

            Best,

            Todd
            ------------------------------------------------------------------------------------
            K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
            ------------------------------------------------------------------------------------
            QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design


            [Non-text portions of this message have been removed]
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