Homebrew PCBs

Today I remembered to heat my etchant.  I just ran hot tap water into
a large container, and floated the FeCl container in it.

Although it had cooled some (the water bath) by the time I got around
to etching (had problems with blue TT paper, ended up using white),
the etchant was still warm enough that the copper almost seemed to
just wipe off with the sponge!  The board was etched in no time.

So if any of you haven't tried heating your etchant yet, try it!

DJ

Basic:
All  chemical reactions are speeded up under heating.
Most "Pro" etch machines have heaters.

Roland F. Harriston
*******************


DJ Delorie wrote:

>
>
> Today I remembered to heat my etchant. I just ran hot tap water into
> a large container, and floated the FeCl container in it.
>
> Although it had cooled some (the water bath) by the time I got around
> to etching (had problems with blue TT paper, ended up using white),
> the etchant was still warm enough that the copper almost seemed to
> just wipe off with the sponge! The board was etched in no time.
>
> So if any of you haven't tried heating your etchant yet, try it!
>
> DJ
>
>

DJ Delorie wrote:
> 
> 
> 
> Today I remembered to heat my etchant. I just ran hot tap water into
> a large container, and floated the FeCl container in it.
> 

I put the FeCl3 etchant directly in the microwave oven. Much more 
efficient in both time and energy. Strangely, the liquid does not seem 
to be conductive enough to cause excessive localized heating on the 
plasticware.

Adam

Submersible aquarium heaters work quite well.  submersible pumps work 
well also.

Aeration creates aerosols that you probably don't work.  I etched the 
heads off of every nail in a storage shed that way :)

Roland F. Harriston wrote:

> Basic:
> All  chemical reactions are speeded up under heating.
> Most "Pro" etch machines have heaters.
>
> Roland F. Harriston
> *******************
>
>
> DJ Delorie wrote:
>   
>> Today I remembered to heat my etchant. I just ran hot tap water into
>> a large container, and floated the FeCl container in it.
>>
>> Although it had cooled some (the water bath) by the time I got around
>> to etching (had problems with blue TT paper, ended up using white),
>> the etchant was still warm enough that the copper almost seemed to
>> just wipe off with the sponge! The board was etched in no time.
>>
>> So if any of you haven't tried heating your etchant yet, try it!
>>
>> DJ
>>
>>  
>>     
>
>
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> If Files or Photos are running short of space, post them here:
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> Yahoo! Groups Links
>
>
>
>

Adam Seychell <a_seychell@...> writes:
> I put the FeCl3 etchant directly in the microwave oven.

I'm pretty sure my wife wouldn't like that.

I got used to the hot water bath technique when the kids were babies
and we had to warm up their bottles.  It was much more consistent and
predictable than the microwave, and with today's bath, I just put it
in there before setting up everything else, and when it was time to
etch it was ready to go - no waiting, no checking.

On 5/18/07, Adam Seychell <a_seychell@...> wrote:
> I put the FeCl3 etchant directly in the microwave oven. Much more
> efficient in both time and energy. Strangely, the liquid does not seem
> to be conductive enough to cause excessive localized heating on the
> plasticware.

Weird, I had the exact opposite experience. I put a 16 oz bottle of
fairly fresh FeCl3 in a microwave (with no turntable). Within a couple
seconds of turning on the microwave, the etchant was boiling around
the meniscus, and started to melt the plastic bottle. Fortunately I
stopped the microwave before the bottle had a chance to spring a leak.

Cheers,
- Jan

Jan Kok wrote:
> 
> Weird, I had the exact opposite experience. I put a 16 oz bottle of
> fairly fresh FeCl3 in a microwave (with no turntable). Within a couple
> seconds of turning on the microwave, the etchant was boiling around
> the meniscus, and started to melt the plastic bottle. Fortunately I
> stopped the microwave before the bottle had a chance to spring a leak.

I too use the full strength FeCl3, but I don't think that will make it 
less conductive. My oven has a turntable, so maybe that makes all the 
difference. It could also be you have a fair more powerful oven, as mine 
is a fairly old 700W. I've never seen a domestic microwave oven without 
a turntable. The etchant does get hotter at the meniscus , but I've 
never witnessed boiling. I usually do it in 30 second bursts followed by 
a quick stir just to make sure I don't run into those troubles.

Dale Chatham wrote:
> Submersible aquarium heaters work quite well.  submersible pumps work 
> well also.
>
> Aeration creates aerosols that you probably don't work.  I etched the 
>   
So aeration is not the same as having bubbles in the etchant?
> heads off of every nail in a storage shed that way :)
>
>   
That sounds like it makes it harder for the walls to stay put.... !

Cheers,

Bryan

I hate make harsh comments on any public forum,
but I think that heating ferric chloride in a microwave
oven is sheer insanity.

The outgassing of fumes will attack and destroy all
metallic circuit components in or near the oven, including circuit boards
copper (and aluminum, and steel) wiring, etc.

I don't  think I've ever, in my 40plus years in the
electronics biz, every heard of anything as bazaar as
"cooking" an etchant in
a microwave oven.

Sorry for the rant,  but I just can't let this one
go by without moaning and groaning.

Roland F. Harriston
********************




Adam Seychell wrote:

>
> Jan Kok wrote:
> >
> > Weird, I had the exact opposite experience. I put a 16 oz bottle of
> > fairly fresh FeCl3 in a microwave (with no turntable). Within a couple
> > seconds of turning on the microwave, the etchant was boiling around
> > the meniscus, and started to melt the plastic bottle. Fortunately I
> > stopped the microwave before the bottle had a chance to spring a leak.
>
> I too use the full strength FeCl3, but I don't think that will make it
> less conductive. My oven has a turntable, so maybe that makes all the
> difference. It could also be you have a fair more powerful oven, as mine
> is a fairly old 700W. I've never seen a domestic microwave oven without
> a turntable. The etchant does get hotter at the meniscus , but I've
> never witnessed boiling. I usually do it in 30 second bursts followed by
> a quick stir just to make sure I don't run into those troubles.
>
>

So what?
If you notice corrosion you can just bring the oven back to the junk place  
and take another with you.
(Keep the transformer if you don't have a battery spot welder yet).

Microwave ovens are usually free, because they are dumped when still quite  
easy to repair. The fan blows air into the electrical compartment (usually  
right) and through the cooking chamber, and out the other side. The dirty  
air does not touch the electrics (it is designed that way to keep food  
dirt off it). So worst case it'll start to rust somewhere...

FeCl doesn't gas much, i would not heat cucl, ever, microwave or not.

ST


On Sat, 19 May 2007 02:26:27 +0200, Roland F. Harriston  
<rolohar@...> wrote:

> I hate make harsh comments on any public forum,
> but I think that heating ferric chloride in a microwave
> oven is sheer insanity.
> The outgassing of fumes will attack and destroy all
> metallic circuit components in or near the oven, including circuit boards
> copper (and aluminum, and steel) wiring, etc.
> I don't  think I've ever, in my 40plus years in the
> electronics biz, every heard of anything as bazaar as
> "cooking" an etchant in
> a microwave oven.
> Sorry for the rant,  but I just can't let this one
> go by without moaning and groaning.
> Roland F. Harriston
> ********************

Stefan Trethan wrote:

> FeCl doesn't gas much, i would not heat cucl, ever, microwave or not.
> 

True. The HCl fumes from CuCl etchants are very corrosive. Although 
FeCl3 does have a tiny bit of HCl, its fumes are much less.

On Sat, 19 May 2007 08:08:10 +0200, Adam Seychell  
<a_seychell@...> wrote:

>
> True. The HCl fumes from CuCl etchants are very corrosive. Although
> FeCl3 does have a tiny bit of HCl, its fumes are much less.


HCl has a very low boiling point.
Even under the boiling point fuming is much increased (look at a cup of  
tea).

I once tried to heat a tiny amount of CuCl in a small glass to compare to  
room temperature, but when i moved my head over the glass i soon dismissed  
the idea.

ST

> So what?
> If you notice corrosion you can just bring the oven back to 
> the junk place and take another with you.
> (Keep the transformer if you don't have a battery spot welder yet).
> 
> Microwave ovens are usually free, because they are dumped 
> when still quite easy to repair. The fan blows air into the 
> electrical compartment (usually
> right) and through the cooking chamber, and out the other 
> side. The dirty air does not touch the electrics (it is 
> designed that way to keep food dirt off it). So worst case 
> it'll start to rust somewhere...
> 
> FeCl doesn't gas much, i would not heat cucl, ever, microwave or not.
> 
> ST


Out of dozens of microwaves I've scavenged, all but one would have worked
with minor repairs.  The exception had a shorted transformer.  Sparks!!!

The rest had a blown fuse.  That's it.  Junked for a $0.50 part.  

Ok, in some cases the varistor (spike supressor) had died, and these tend to
fail shorted.  That takes out the fuse as well.  The other way to blow the
fuse is to try to defeat the door locks.  If you look at the wiring, they
are often rigged so the if one of the microswitches (sometimes up to 6!)
doesn't close, then it causes a dead short across the AC, or ties the AC to
ground (which takes out the breaker as well).  Might fry the microswitch
too.

The curious thing is that as ST says, the air vents thru the food
compartment & out the back.  This means the fans get a lot of crap on them,
but everyone I've tested has worked, no matter how grotty.  If the fan did
fail then the thermal cutout (one on the food comparment, one on the
magentron) will trigger.

That junked microwave you walked past works, go grab it.  Dunno about
heating FeCl (I used the double bowl method), but you can dry green wood
with it.  I wish those dudes melting metal would get a move on.

Tony

> have a fair more powerful oven, as mine is a fairly old 700W. 
> I've never seen a domestic microwave oven without a 
> turntable. The etchant does get hotter at the meniscus , but 


The ones without a turntable have what's called a 'stirrer' up the top.
It's just metal fan in front of the magnetron that bounces the waves around.

I've seen exactly one one these.

I'm not sure why domestic oven use rotating turntables (price,
reliability?).  I think commercial ovens still have stirrers as it means the
handles on the containers you put in will be in the same spot when you open
the door.  Some domestic ovens will rotate the turntable to the 'starting
point' to get the same effect.

Tony

On Sat, 19 May 2007 10:31:53 +0200, Tony Smith <ajsmith@...>  
wrote:

>
> The ones without a turntable have what's called a 'stirrer' up the top.
> It's just metal fan in front of the magnetron that bounces the waves  
> around.
> I've seen exactly one one these.
> I'm not sure why domestic oven use rotating turntables (price,
> reliability?).  I think commercial ovens still have stirrers as it means  
> the
> handles on the containers you put in will be in the same spot when you  
> open
> the door.  Some domestic ovens will rotate the turntable to the 'starting
> point' to get the same effect.
> Tony


I have seen three with stirrers, usually the larger ones have them but i  
also have a very small very early oven with one.

IMO the superior method over the turntable, but a bit more tricky  
technically.
One i looked into used a plastic ball bearing (just like metal only clear  
balls). I suspect the metal ball bearing would cause arcing and wouldn't  
work. The stirrer was powered by the cooling airflow (so the friction  
needs to be low).

ST

> I have seen three with stirrers, usually the larger ones have 
> them but i  
> also have a very small very early oven with one.
> 
> IMO the superior method over the turntable, but a bit more tricky  
> technically.
> One i looked into used a plastic ball bearing (just like 
> metal only clear  
> balls). I suspect the metal ball bearing would cause arcing 
> and wouldn't  
> work. The stirrer was powered by the cooling airflow (so the 
> friction  
> needs to be low).
> 
> ST


The small one I saw had the stirrer run off the airflow.  I suppose that
would clog up the bearing eventually.  Makes sense that they'd work better,
fewer cold spots.

A quick rummage around Google shows stirrers are still around.  Some models
have them in the sides as well.  These are commercial ones, and are driven
by motors (with belts).

Tony

Had to do more adapter boards, this time I timed the etch.  The FeCl
was up to temp (no delay this time), so it was about 115-120F.  Single
sided 1/2 oz copper, the board was 1x2".

Etch time: 90 seconds!