# Kovar



## sharkhook (Dec 31, 2013)

Not being sure where to post this, so I am trying it here.

What electronic components contain kovar? I have just over 1 pound of pins from various boards, etc. none of them are from cpu's. Are the cpu pins the only ones that contain kovar? And if not, how do I identify the ones that do contain the kovar? All of the pin's I have are soft, and easily bendable, but they are mixed magnetic and non- magnetic.


----------



## butcher (Dec 31, 2013)

Kovar, An iron compound with about 54% Fe, 29% nickel, 17% cobalt, and traces of silicone, carbon, and manganese, usually used where they need strength or a springy metal.

Beryllium copper is another alloy used, where they need a spring metal or where strength or stress may prove a problem for the softer copper metal, where non sparking may be needed, or a non ferrous metal is needed, beryllium copper can have about 0.5% to 3% beryllium, and many time cobalt and nickel are part of the alloy.

Kovar with all of that iron is much more magnetic than beryllium copper, or the copper pins with a tiny bit of the weakly magnetic nickel plating under the layer of gold.

A strong magnet may attract the nickel, where a weaker magnet would not, and where the weaker magnet would only attract the iron in the Kovar.

If the copper is hard and springy, I would suspect beryllium, pure copper is fairly soft (will cut easy with a knife), and bends easily
In electronic scrap you will find these metals used where they are needed to better perform a function, or are needed to insure reliability, pins that may bend easy may use the stronger Kovar, contact may use beryllium to insure good contact, or for its springy nature, or to strengthen the pins from being bent out of shape by plugging in or unplugging connections…


----------



## sharkhook (Dec 31, 2013)

Thanks butcher,

Is it safe to assume that the weaker magnet will separate them for processing? I need to reread several posts and find a way to process both types. I have only used AP in the past. I do have most of the stuff for a sulfuric cell, I have never had enough pins to attempt the use of one, although I have just over 1200 grams now and have about 10 more computer boards and 30 hard drives to cut yet.


----------



## goldsilverpro (Dec 31, 2013)

Kovar is often used when an expansion match is needed for a glass-to-metal seal, such as on many CPU packages. Anytime glass is next to metal, if the expansion coefficients of the 2 are different, separation can occur and there can be air leakage. The kovar alloy is chosen because it matches the expansion coefficient of the glass.


----------



## Geo (Jan 1, 2014)

AP will digest Kovar but at the price of the AP solution. after the solution dissolves enough iron to reach the saturation point, it will no longer dissolve iron or much of anything else.


----------



## butcher (Jan 1, 2014)

I reuse this solution to dissolve copper and base metals.

Actually it become more of an iron chloride, if strongly heated you will be amazed at how much copper you can dissolve with this old used (AP leach), the iron chloride will dissolve pounds of copper in a corning dish on a hot plate when the solution get thick brown, decant a portion of the leach into a cooling jar there most of the copper will settle out as copper I chloride (a brown powder, unless diluted with water which will turn it white as acids are diluted) after settling you can return iron chloride liquid back to the corning dish to dissolve more copper,

The copper I chloride powder washed with a little water will give a white powder of copper I chloride this rinse liquid you can add back to the heated corning dish above to dissolve more copper.

This leaves you with the white copper I chloride powders, with some HCl add this dissolves and becomes copper II chloride, which can be used, as you know to dissolve copper, and if you had silver or gold on the copper you were dissolving above, you will be left with gold foils or silver chloride powders after adding the HCl.


----------



## sharkhook (Jan 1, 2014)

Thanks, everyone, some most useful information.


----------



## butcher (Jan 1, 2014)

This is a hard subject to explain but I will try.
Reuse of old copper II chloride leach that has become loaded with iron, and can actually become an iron chloride or and iron/copper chloride solution.

First lets look at what happens when we use our (AP) copper II chloride to dissolve Iron, we convert the copper II chloride CuCl2 (cupric chloride), to FeCl2 (ferrous chloride) and copper metal powders.

CuCl2 + Fe --> FeCl2 +Cu

Our solution during this reaction may actually have several copper and iron chloride salts involved before the above reaction is driven to completion.

Now once we end up with iron II Chloride FeCl2 (ferrous chloride) we normally think of our (AP) or copper II chloride as spent or waste, because FeCl2 is just about useless to attack copper.

But we can use this old spent leach solution to dissolve base metals, and actually we can reuse it to dissolve a heck of a lot more copper (not as FeCl2 but we can get FeCl3 from this solution).

Lets look at some iron chemistry to set up this discussion.

If we dissolve Iron (Fe) in HCl we can make ferrous chloride.
Fe + 2HCl --> FeCl2 + H2

This FeCl2 ferrous chloride will not readily attack copper.
But if let the acidic FeCl2 (ferrous chloride) set exposed in air for a long period of time it will absorb oxygen and oxidize to ferric chloride FeCL3.
4FeCl2 + O2 + HCl --> 4FeCl3 + 2H2O
we can speed this oxidation of ferrous chloride (FeCl2) to FeCl3 (ferric chloride) by adding about equal volumes of 3% H2O2 solution.
FeCl2 + H2O2 --> FeCL3

I have also found just strongly heating the solution also help it to absorb oxygen especially when the solution is concentrated.

Now Ferric chloride FeCl3 is a great etch for copper metals, hot concentrated solutions heated to a thicker solution, help to convert silver to silver chloride the heavy brine solution helps to remove the silver chloride crust that forms, gold is not attacked but plated gold will flake off as copper underneath is attacked.

Ferric chloride is used to etch copper circuit boards, just the same way the copper II chloride leach we call acid peroxide is used, the main reason to use CuCl2 cupric chloride leach over the ferric chloride leach to dissolve copper is the ease of which we can rejuvenate the cupric leach for reuse, in a copper cycle.
we can also rejuvenate the Iron chloride leach, but it is not as easy to get the copper back out of the leach.

I have stumbled on a way to use the ferric chloride leach (our old spent copper chloride leaches), by reusing my waste solution to dissolve base metals.
And actually make a copper II chloride leach from the copper I chloride powders in the process.

First we need to look at the two-step process of using ferric chloride FeCl3 to etch copper.
FeCl3 + Cu --> FeCl2 + CuCl
then
FeCl3 + CuCl --> FeCl2 + CuCl2
notice in the first part of reaction we can form CuCl, and later in the reaction the CuCl is oxidized to CuCl2, as the FeCl3 is reduced to FeCl2.
And in the second part of the reaction we end up with both iron and copper chlorides in solution as FeCl2 and CuCl2.

If we stop this above reaction in the middle we can separate most of the CuCl and let the concentrated solution cool and settle to powders of CuCl, AgCl and Au foils.
Returning most of the FeCl2 to the main reaction to help dissolve more copper as it picks up air (or we can add a little H2O2 to convert the FeCl2 back to FeCl3...

This is what I tried to explain in the post above.
Where I said:
I reuse this solution to dissolve copper and base metals.

Actually it become more of an iron chloride, if strongly heated you will be amazed at how much copper you can dissolve with this old used (AP leach), the iron chloride will dissolve pounds of copper in a corning dish on a hot plate when the solution get thick brown, decant a portion of the leach into a cooling jar there most of the copper will settle out as copper I chloride (a brown powder, unless diluted with water which will turn it white as acids are diluted) after settling you can return iron chloride liquid back to the corning dish to dissolve more copper,

The copper I chloride powder washed with a little water will give a white powder of copper I chloride this rinse liquid you can add back to the heated corning dish above to dissolve more copper.

This leaves you with the white copper I chloride powders, with some HCl add this dissolves and becomes copper II chloride, which can be used, as you know to dissolve copper, and if you had silver or gold on the copper you were dissolving above, you will be left with gold foils or silver chloride powders after adding the HCl.

So here we get our CuCl back to make a new CuCl2 leach solution (acid peroxide leach), we concentrate our old iron chloride solution (to treat for waste) giving us less waste to deal with.
And dissolve pounds of copper from things like contact points with chunks of copper that were cut from the relay or motor contactors, or gold foils from copper brass or iron pins...

Reusing a solution that was once considered a waste solution, to do more work dissolving pounds of copper, collecting a useful copper I chloride we can make into a fresh copper II chloride leach, and collect silver and gold, while reducing the left over waste solution to deal with.


----------



## sharkhook (Jan 1, 2014)

Thanks, once again, butcher.
You have a great way of explaining things in simple terms, then by adding the technical explanation it gives a beautiful understanding as well as an educational understanding. That is very hard to do. I had only a couple of teachers, while in school that could give such prime examples.


----------



## solar_plasma (Jan 19, 2015)

While trying to dissolve kovar in used but not spent, hot HCl/CuCl2 the green leach got discolored and there was not much reaction anymore. Some copper metal had cemented out. After thinking the proces back and forth I added pure CuCl2. The solution turned immediately black-brown and after 10 minutes of aeration dark emerald green. Now, a reaction is visible, small bubbles here and there of maybe hydrogen are forming and first pieces of gold plate are flaking off after only 30 min.

My theory was, that the CuCl2/CuCl/Cu0-system is working like a catalyst, where the cementing copper dissolves the kovar and then is oxidizing back to Cu(II).

Whatever the correct explanation may be, obviously the addition of pure powdered CuCl2 makes the solution more sharp. Surely it is the same effect as concentrating the leach by evaporation like Butcher described many times.


----------



## solar_plasma (Jan 24, 2015)

Though I've seen a few TO5 dissolved well together with a batch of pins in a lot of CuCl2/HCl, for greater amounts of kovar this isn't the way to go! 10 days and most of the capsules are more or less intact. Yes, I read all the other possibilities to treat kovar, but I didn't understand HOW slow AP is working here.

Next time I use dilluted sulfuric. Would 4M H2SO4 at 60-80°C be okay and if so, how long would it take, hours, days, weeks?


----------



## Geo (Jan 24, 2015)

Have you tried ferric chloride? It works almost as aggressively as nitric acid when heated.

Also, did you add an oxygen source to the heated AP solution?


----------



## solar_plasma (Jan 24, 2015)

No, I didn't try ferric chloride, but now I've added my last 200 g to the 1kg to5 batch, that already has lost 20% of it starting volume. Should not harm. Most of the copper seems to be cemented out.

Yes, I used air, but I stopped 2 days ago, because there is visible steady gas evolution, I hope hydrogen caused by dissolving iron, even without air.


----------



## solar_plasma (Jan 24, 2015)

Rereading Butcher's post above:


> This FeCl2 ferrous chloride will not readily attack copper.
> But if let the acidic FeCl2 (ferrous chloride) set exposed in air for a long period of time it will absorb oxygen and oxidize to ferric chloride FeCL3.
> 4FeCl2 + O2 + HCl --> 4FeCl3 + 2H2O
> we can speed this oxidation of ferrous chloride (FeCl2) to FeCl3 (ferric chloride) by adding about equal volumes of 3% H2O2 solution.
> FeCl2 + H2O2 --> FeCL3



I will watch the reaction now and try to reactivate the ferric as soon, as it seems to be used up.

Thanks for the hint with ferric, Geo!


----------



## solar_plasma (Jan 29, 2015)

Just checked single TO5s in probes for 24 hours at 20C:
2M (about 20%) sulfuric - some small bubbles in the beginning, no effect
konc. sulfuric - ofcourse no effect due to passivation
1M (about 6%) nitric - turned dark green, corrosion visible
10M (63%) nitric - light green, no corrosion visible (passivation)

Wikipedia says, that at 40% nitric, nickel will show a significant passivation. So, it would be interesting to see, which concentration between 1M and 5M works fastest.


----------



## solar_plasma (Jun 11, 2015)

Ok, finally, 1kg TO5 kindred photo transistors are done after half a year in spent AP/fresh AP/CuCL2/FeCl3/straight HCl/warm/cold/with and without aeration (time enough to try almost everything :lol: )

The yield seems in this case to be around 6g/1kg. Maybe I'll get some more 1/10 g. All transistors had golden legs and a big part of them had the gold rim. The solder under the die has been silver-gray, not golden.


----------



## Anonymous (Jun 11, 2015)

Bjorn are we on a wine making forum or a gold making forum? 8) :lol: 

Jon


----------



## solar_plasma (Jun 11, 2015)

spaceships said:


> Bjorn are we on a wine making forum or a gold making forum? 8) :lol:
> 
> Jon



 :lol: 

You can imagine I have spent a lot of time thinking over, why this batch has been that slow. I think it is because there has been too little liquid on top of the transistors and almost no agitation.


----------

