On Sat, 30 Mar 2013 08:48:37 -0700, you wrote:
>How did you protect the back of the aluminum. I tried applying wax but I
>think it melted off. Also tried electrical tape and it fell off. Maybe the
>common factor here is the heat generated by the too strong lye/water
>mixture. I was thinking about using a Q tip and just dip it in the lye/water
>mixture and dab it on the masked off area.
It's the heat. You can use the transparent (I like transparent here)
shelf covering. The one thing of the "Martha Stewart" brand that I'll
every buy. Cut to size and the adhesive lasts through an etch.
You'd not want to etch too much here, you left it in way too long. I'd
definitely dilute the lye to get it to act more slowly.
Ferric chloride does react with aluminum, if not the ferric chloride
itself, then the excess chloride ions. That's why they tell you never
to etch in an aluminum pan.
A Q tip of diluted mixture would work well, you can rinse it off and
see how deep it is.
>
>I've had very poor luck with toner transfer. The closest I came to success
>was with copper.
I use it on PC boards, works well once you get the parameters right.
>
>I will be using my new spray on photo resist and a contact print. But first
>I want to perfect the etching process with just masking using tape, wax, or
>??.
You may also want to try making a small dam with clay or plumber's
putty and etching only a small area (if needed).
Harvey
>
>Rick
>
>-----Original Message-----
>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>On Behalf Of Harvey White
>Sent: Saturday, March 30, 2013 8:36 AM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] lye
>
>On Sat, 30 Mar 2013 07:31:42 -0700, you wrote:
>
>>Has anyone used lye to etch aluminum through photo resist?
>>
>>
>>
>>As a test, I put a strip of aluminum in lye plus water and after 15
>>minutes the strip was half of its original thickness. So there is no
>>doubt that lye can etch VERY deep. But the chemical reaction generated
>>a lot of heat and the tape I had on there quickly floated off. Next
>>time I will use more water.
>
>I did so a long time ago with photoresist, the back of the aluminum was
>protected, and it was potassium hydroxide not sodium hydroxide. It did work,
>though. I filled the etch with ink then lightly sanded the surface. Worked
>well.
>
>I'd do it with toner transfer were it not for the problems with getting the
>entire piece of aluminum to temperature (as well as potential thickness
>problems. Possibly a T shirt press would work.
>
>also need a negative mask.
>
>Harvey
>
>>
>>
>>
>>I did have the lye and aluminum outside while I watched from inside.
>>Nasty fumes!
>>
>>
>>
>>Thanks,
>>
>>
>>
>>Rick
>>
>>
>>
>>[Non-text portions of this message have been removed]
>
>
>
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