[AR] Re: Electroforming Experiment
- From: Peter Fairbrother <peter@xxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Sun, 14 Jul 2019 21:51:34 +0100
On 14/07/2019 19:58, Norman Yarvin wrote:
On Sun, Jul 14, 2019 at 02:48:06PM +0100, Peter Fairbrother wrote:
Mechanically strong enough for a
combustion chamber?
The copper layer can be fairly strong at room temperature, but it
contains phosphorus, which destroys the high-temperature properties of
the copper, making it totally unsuitable for a chamber.
There's no phosphorus in this particular formulation. (The list of
ingredients is at 5:15 in the video.)
I hadn't watched the video, but the most usual form of electroless
copper uses sodium hypophosphite are the reducing agent rather than
formaldehyde. Use of formaldehyde is uncommon, and the deposit isn't as
good.
Also, the video guy is trying to do something other than standard
electroless copper, he wants to laser print where the copper attaches. I
don't know why he used formaldehyde.
Would formaldehyde copper have good high-temperature properties? I don't
think so, I think I remember reading somewhere that it would not, but I
can't find the reference offhand. Please don't expect me to be as
consistently knowledgeable and correct as Henry!
But in any case, you couldn't make a layer of electroless copper thick
enough for a chamber wall, no matter whether you used hypophosphite,
formaldehyde or dimethylamine borane as the reducing agent.
Personally I think his method is a bit silly: you would get a much
better and a much easier result if you electroless plated the whole
object, then electrolytically plated it to build up a thick enough layer
to be useful, applied photoresist, then used the laser selectively on
the photoresist.
BTW also, the video guy makes some basic mistakes; eg on the solubility
of copper sulphate pentahydrate in water, which is above 30 g/l at all
useful temperatures, and is never less than 5 g/l. A layer of
electroless copper is not really thick enough for a conductive trace.
and his best results would have been rejected by the easiest pcb
inspectors I ever met... I am not very impressed with his results,
though he does have a nice technique.
Peter Fairbrother
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