Sciencemadness Discussion Board - Drying hydrated copper formate

Drying hydrated copper formate

huegene - 3-12-2015 at 11:46

Hi everyone,
I intend to deposit copper into printed circuit board holes (aka through hole plating)
by thermal decomposition of (anhydrous) copper formate.
Can anyone tell me how to dry copper formate without decomposing it? When heating it up, it "melts" at some point and then decomposes.
Is it even possible to dry hydrated copper formate?

Thank you for your attention.

Metacelsus - 3-12-2015 at 16:04

A few years ago, I tried to get copper(II) acetate monohydrate to anhydrous by careful heating. At atmospheric pressure, it always decomposed; I had to use vacuum to get it to work.

I would suggest vacuum. You could also try (if possible) recrystallizing from a solution in 90% formic acid.

From this paper: Anhydrous copper formate is made from reacting basic copper carbonate with excess 90% formic acid.

huegene - 3-12-2015 at 16:31

It took me some more searching but I've finally got some numbers. This patent: http://www.freepatentsonline.com/5094686.html suggests drying at 130°C. I guess, now it's finally the time to invest in that "high power Mosfet bridge (+Oscillator)" for inductive heating, to be able to dry under vaccum while heating it in the desiccator ;-).
It's such a pity that it took me so long to find this information, because I've been browsing this patent briefly before and not paying attention to that information while beeing focused on reduction issues and mirror formation.

anyway thanks a lot.
When ( If

) I am successfull with that plating process I'll post some more details and pictures.

Metacelsus - 3-12-2015 at 21:50

Induction heating will not work for a non-conductive material such as a solid salt.

[Edited on 12-4-2015 by Cheddite Cheese]

huegene - 7-12-2015 at 11:02

I know,
i mean to wirelessly transport energy into the desiccator having a reception coil inside or just a graphite plate that heats up the contents.

huegene - 1-3-2016 at 06:39

Small update and Problems:
so for now i have been able to decompose the copper formate to copper, but it tends to decompose on its own, even in an air tight container.
At first i thought it decomposed because i kept it in a desiccator under calcium cholride, but now as it decomposed again ( color change from sky blue to something similar to copper carbonate or hydroxide) just while sitting in a jar, i suspect that it is very photosensitive.

blogfast25 - 1-3-2016 at 06:59

Quote: Originally posted by huegene

Small update and Problems:
so for now i have been able to decompose the copper formate to copper, but it tends to decompose on its own, even in an air tight container.

At first i thought it decomposed because i kept it in a desiccator under calcium cholride, but now as it decomposed again ( color change from sky blue to something similar to copper carbonate or hydroxide) just while sitting in a jar, i suspect that it is very photosensitive.

To copper??? Cu(0)?? Are you sure of that?

Like other carboxylic acids, formic acid is a fairly weak acid (Wiki, pK_a = 3.77) Formate, in the absence of excess formic acid, thus has a tendency to hydrolyse:

HCOO<sup>-</sup>(aq) + H₂O(l) <===> HCOOH(aq) + OH<sup>-</sup>(aq)

That's why salts like that tend to convert to Cu(OH)₂, in the absence of excess HCOOH. Light has very little, if anything, to do with it.

[Edited on 1-3-2016 by blogfast25]

huegene - 17-3-2016 at 10:32

the decomposition in the desiccator was different from the one upon heating it.
When heated, yes it decomposes to elemental copper.
http://www.freepatentsonline.com/5094686.html