Homebrew PCBs

Harvey,

Brilliant suggestions! Gotta try them all in the next day or two.

Thanks,

Rick

On Mar 30, 2013, at 9:01 AM, Harvey White <madyn@dragonworks.info> wrote:

> 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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> 
> 
> 
> ------------------------------------
> 
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
> 
> 
>