There’s Gold in Copper

Copper prices have jumped 25% in the past month, much of the gains coming in the past week. Can it last?

Analysts are mixed. While most agree that pricing is well above the level its fundamentals suggest it should trade at, some feel better news from China and an expected boon for infrastructure spending in the US will increase demand over time.

Others think the speculation is overblown.


Reader Mail

Some time ago I wrote a post, “Questions on Tin Whiskers.” Reader Michael responds below. He makes some good points.

Dr. Ron, I’m responding to your blog regarding tin whiskers. I actually have a failure analysis report I did a couple of years ago in which failure of our product was due to this issue and occurred on a part that came into RoHS compliance only 3 months prior.

I’m not sure that your question of identifying whisker issues in product that proper steps have been taken to mitigate the problem is a constructive one. The fact is that many of the component manufacturers from overseas jumped into compliance without any thought or regard to this issue thereby flooding the industry with components such as plagued my company. We have not had this issue since we’ve specified an alternate finish.

These whiskers are so delicate that most problems disappear when the technician starts to work on the failed unit and the problem never re-appears so it is written off as an anomaly, loose/bad connection and not investigated any further. It was only my own curiosity as to the number of “no problem found” failures of our keypads we had suddenly encountered that caused me to dig deeper and when I looked into the connector I was amazed at the crystal city staring back at me. I couldn’t believe what I was seeing after all of these years.

After seeing this problem first hand I became, and am, quite convinced that there were and are people who will be losing life, limb, and property because this forced compliance with its risk was not given proper worldwide attention.


A popular topic on my blog is solder density calculations. Rhonda writes

Hi Dr. Lasky,
I am a precious metals recycler and would very much appreciate your verifying the validity of an equation that approximates the Karat Value of various alloys of gold based on S.G. which I will call density or “D,” and the Karat Value is “K.” The equation is seems to hold relatively true even when the exact composition of the alloy is unknown, although the percent of error obviously will increase as density decreases. I would also appreciate not only verification but also more specific information on percent of error for densities below about 14 or 15 g/cc. Here is the equation:

K = 0.0089D^3 – 0.550D^2 + 12.5299D – 77.06

Thank you so much for whatever assistance you can provide.

These types of equations can only work for one alloying metal with the gold.  This one is only for copper.  It is also calibrated in Rhonda’s favor as it reads the karat level about 10% low.   I was able to determine this by using the Excel Solder Density worksheet that I developed. If the alloy was gold and lead, a 50% by weight gold (12 karat) would show as 15.7 karat with this equation and Rhonda would lose her shirt.


In response to my blog post on copper as the precursor to civilization, Harvey writes about pollution from early mining operation.

Also interesting, early copper mining and processing led to the first examples of human induced environmental damage. There are documented sites in the Alps where copper processing by prehistoric peoples has left areas treeless to this day, due to heavy metal contamination.

Mining and smelting were very tough businesses in ancient days.  In addition to pollution, many workers died from toxic fumes.

Dr. Ron

Musings on Metals: Copper

It could be argued that civilization began with the smelting of copper.  Although thousands of years before, humans fired clay to make figurines and containers, smelting required several non-obvious steps.  After all, the firing of clay, at some level, can be accomplished by simply dropping clay into a fire.

To smelt copper, our ancestors had to:

  1. Take malachite (see photo) or another copper ore, grind it up or break it into small pieces
  2. Mix the ground malachite with carbon
  3. Heat the mixture in a vessel to 1,085oC.

Malachite Ore

Achieving this temperature with a wood fire is, to me, astounding.  Think about those days when you are grilling some burgers.  You leave the grill on after the burgers are done, to burn off the grease.  You come back 20 minutes later and the grill is at 500oF.  You can feel the heat.  Even touching the knob to turn the gas off is intimidating, as the heat drives you back.  This temperature, 500oF, is only 260oC!  The ancients reaching 1,085oC with wood and bellows is, indeed, impressive. By the way, a good rule of thumb to convert degrees C to degrees F from 100oC to 1,5000C is that 2XC=F, this fast approximation is accurate to about 10% in this range.

The confluence of the three procedures is not only non-intuitive, but think how many times the smelter of old could only reach 900oC and failed.  I have argued that if copper melted at 1,200oC or so, civilization would have never gotten started.  This temperature is perhaps a little too high to reach with a wood fire.  The smelting of copper encouraged investigations into other metals, eventually resulting in the discovery of the processing of iron, an even less intuitive process than smelting copper.  So, I believe that the success with copper was necessary to the production of steel.

Copper smelting became an industry that encouraged permanent settlements and stimulated trade, which encouraged writing and ciphering.  An effective copper smelter would likely keep secret some of his craft as he wanted a competitive advantage.  He could make more by smelting copper than doing anything else, so he almost certainly was an early specialist.

Considering all of this, I believe that without the discovery of copper smelting, we might still be living in huts or teepees, using stone tools, and living a nomadic existence without commerce, writing, or mathematics.  Examples to support this thesis are the state of native peoples in the Americas in the 1400s.  These native peoples had never learned to smelt metals and hence also lacked the follow-on aspects of civilization mentioned above.

Today, copper is a foundation material for electronics, given its excellent electrical conductivity, second only to silver.  Copper’s ductility likely aids in the formation of PWB traces and plated through-holes in that it resists cracking.

Additionally, copper’s ability to form an electrical and mechanical bond with solder is another trait that makes it a winner as an electrically-conductive assembly material in modern electronics.

Copper has been used for more than 10 millennia, but, as with most metals, 90 to 95% of it has been mined since 1900.  About 15 million metric tons (MT) are used each year, third to aluminum’s  22 million MT and steel’s unequaled 1 billion MT.

In the next installment, we will discuss tin and how it forms an intermetallic with copper during soldering.  Thus making solder paste, solder wire, and solder preforms critical components of electronics assembly.


Dr. Ron