Homebrew PCBs

I know that placing metal in a microwave can produce "interesting" results.
However is there any experience with a piece of copper in a cup of water?
I'm speculating that the water may keep the copper from being the primary
load on the microwave and also provide a cooling surface for the copper.

Just interested in heating a persulfate etching solution.

tnx
jtm


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

Jim Miller wrote:
> I know that placing metal in a microwave can produce "interesting" results.
> However is there any experience with a piece of copper in a cup of water?
> I'm speculating that the water may keep the copper from being the primary
> load on the microwave and also provide a cooling surface for the copper.
> 
> Just interested in heating a persulfate etching solution.

I usually strip the resist off a pcb while it's in 5mm of NaOH in a flat
tray, and the tray is in the microwave.

On Fri, 12 Dec 2008, Jim Miller wrote:

> I know that placing metal in a microwave can produce "interesting" results.
> However is there any experience with a piece of copper in a cup of water?
> I'm speculating that the water may keep the copper from being the primary
> load on the microwave and also provide a cooling surface for the copper.
>
> Just interested in heating a persulfate etching solution.

I think the problem is that metal in the microwave serves as a reflector.

-- 
David Griffith
dgriffi@...

A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

Any particular power setting or just on full? How long do you have it 
in for?

Any particular issues with how much copper is left on the board, i.e. 
is there a problem with a full ground plane or ground pour?

tnx
jtm
 
> I usually strip the resist off a pcb while it's in 5mm of NaOH in a 
flat
> tray, and the tray is in the microwave.

--- In Homebrew_PCBs@yahoogroups.com, "Jim Miller" <jim@...> wrote:
>
> I know that placing metal in a microwave can produce "interesting" 
results.
> However is there any experience with a piece of copper in a cup of 
water?
> I'm speculating that the water may keep the copper from being the 
primary
> load on the microwave and also provide a cooling surface for the 
copper.
> 
> Just interested in heating a persulfate etching solution.
> 
> tnx
> jtm
> 

That is an interesting concept.  I usually use a Pyrex tray on the 
Propane fired stove.  I like my Ferric-Chloride at about 135 to 140 
degrees F when etching my PCBs.

All I can recommend is try it for a few seconds.  If you don't see 
lightning bolts streaking across the inside of the microwave, try it 
again for a bit longer time, gradually increasing the time until you 
see success, or lightning.

The thing about metal in a microwave is that, the metal represents a 
substantial load on the microwave tube - especially when the metal is 
in the shape of a ring.  So the size of the PCB will be very 
limited.  How limited will depend on the power rating if the 
microwave oven.

Carl W. Livingston, KC5OTL

> I know that placing metal in a microwave can produce "interesting" 
results.
> However is there any experience with a piece of copper in a cup of 
water?
> I'm speculating that the water may keep the copper from being the 
primary
> load on the microwave and also provide a cooling surface for the 
copper.
> 
> Just interested in heating a persulfate etching solution.
> 
> tnx
> jtm
I prefer to heat my solution and then etch. It seems to keep warm 
enough to etch a board. The etchent can also eat your microwave metal 
parts. I am thinking a fishtank heater would do the same. Just takes 
longer to heat.

Brian

mdgolfbum wrote:
> Any particular power setting or just on full? How long do you have it 
> in for?

Leave on full for 1 minute or less, so that it's hot but not boiling.

> Any particular issues with how much copper is left on the board, i.e. 
> is there a problem with a full ground plane or ground pour?

No. As long as there's 2-3mm of liquid over the pcb, any resonances in
the copper are sufficiently damped by the liquid conductivity that there's
no problem with HV arcing.

The resist doesn't strip straight away. I take the tray out and rock it
for some agitation and the resist starts coming off a minute later.
Turn the pcb over to do the other side too.

A good test of this theory would be a blank cd in a (glass) pan of water.
 
Normally, CD's aluminum layer will melt within 5 seconds in an active
microwave.
I use this method to distroy CD's with confidental information 
 
HughAW

  _____  

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Jim Miller
Sent: Friday, December 12, 2008 6:10 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Potentially stupid or brilliant idea



I know that placing metal in a microwave can produce "interesting" results.
However is there any experience with a piece of copper in a cup of water?
I'm speculating that the water may keep the copper from being the primary
load on the microwave and also provide a cooling surface for the copper.

Just interested in heating a persulfate etching solution.

tnx
jtm

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



 


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

----- Original Message ----- 

From: "Jim Miller" <jim@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, December 13, 2008 2:09 AM
Subject: [Homebrew_PCBs] Potentially stupid or brilliant idea


>I know that placing metal in a microwave can produce "interesting" results.
> However is there any experience with a piece of copper in a cup of water?
> I'm speculating that the water may keep the copper from being the primary
> load on the microwave and also provide a cooling surface for the copper.
>
> Just interested in heating a persulfate etching solution.

Microwaveable chips use metallised cardboard in the container, FWIW.

Leon
--
Leon Heller
Amateur radio call-sign  G1HSM
Yaesu FT-817ND transceiver
Suzuki SV1000S motorcycle
leon355@...
http://www.geocities.com/leon_heller

Leon Heller
Amateur radio call-sign  G1HSM
Yaesu FT-817ND transceiver
Suzuki SV1000S motorcycle
leon355@...
http://www.geocities.com/leon_heller

----- Original Message ----- 
From: "Jim Miller" <jim@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, December 13, 2008 2:09 AM
Subject: [Homebrew_PCBs] Potentially stupid or brilliant idea


>I know that placing metal in a microwave can produce "interesting" results.
> However is there any experience with a piece of copper in a cup of water?
> I'm speculating that the water may keep the copper from being the primary
> load on the microwave and also provide a cooling surface for the copper.
>
> Just interested in heating a persulfate etching solution.

I simply place the container in an old washing up bowl with about an inch of 
just boiled water in it. That keeps it nice and hot; etching takes about 5 
minutes with ferric chloride.

Leon

Jim Miller wrote:
> Just interested in heating a persulfate etching solution.

It works fine. Like Russell said, the liquid must dampen resonances 
because I've never seen any burning or arcing of any sort on the copper 
that is immersed in solution. Also remember etchants are very conductive 
compared to water. I often heat ferric chloride with the PCB in it.

Adam