What is Tin?

By The Metallurgy Experts at Metallic Resources

Tin is a chemical element with the symbol Sn and atomic number 50.  First discovered as early as 3,500 B.C., tin is one of the earliest known and used metals.  Tin is a silvery-white, slightly bluish-tinged metal which does not occur as a native element, but rather must be extracted from its naturally occurring mineral ores.  The main mineral ore for tin is cassiterite (SnO2) – frequently called “tin ore”.  Tin’s melting point is 449.5°F.
With many diversified commercial and industrial applications, tin is typically considered a base metal (that is, a common and inexpensive metal) as opposed to an expensive precious metal (such as gold or silver) or a noble metal.  Tin’s wide-ranging applications can be traced to its useful performance characteristics.  Among others, tin metal is soft, nontoxic, ductile, malleable, durable, exhibits high corrosion resistance (given that it is little affected by air at ordinary temperatures), and alloys well with other metals.  These features make tin suitable for use in solder, brass, bronze, plating (to protect other metals from corrosion), and various chemicals. As the International Tin Association explains: “Tin is called the ‘spice element’ because a little of it is present everywhere in ways that are essential to our quality of life.”
Of its many applications, one of the most important uses of tin is in solder.  Solder, by definition, is a fusible metal alloy used to bond metal workpieces together.  With tin usually serving as the main constituent in many solder alloys, it is estimated that around 50% of all tin produced goes into solder – mainly for electronics.  The most common solder alloys are (1) tin/lead (such as the eutectic alloy Sn63/Pb37, Sn60/Pb40, and Sn50/Pb50) and (2) lead-free – including SAC305 (Sn96.5/Ag3/Cu.5) and non-silver bearing alloys such as Metallic Resources’ patented SC995e™.
Notwithstanding its widespread use, tin is a relatively scarce element, as it represents only 2 parts per million (ppm), or less than 0.001%, of the Earth’s crust – compared with approximately 90 ppm for zinc, 60 ppm for copper, and 10 ppm for lead. Fortunately, refiners like Metallic Resourcescan infinitely recycle scrap tin, tin oxide and tin dross back to high-quality, clean tin metal and solder suitable for use in the electronics industry and elsewhere.  The recycling of tin and tin byproducts is sustainable and ecofriendly because it reduces waste disposal, emissions, energy usage.  In addition, usage of high-purity recycled tin (like Metallic Resources’ electrolytic tin) in favor of tin mined from the ground avoids the harmful effects to the environment created by mining.

Electrolytic Solder Outperforms The Competition

By David Bao, Ph.D.

The discerning electronics manufacturer needs to know that there are three grades of solder.  In order from highest to poorest grade, they are: (1) electrolytic; (2) virgin; and (3) reclaim.  As the original innovator and leader in electrolytic solder, the solder manufactured and sold by Metallic Resources is 10 times more pure than traditional standards.
Beginning at the bottom, reclaim solder is the poorest since the reclaimer simply takes contaminated pot metal, smelts the dross out of it, recasts it, and sells it. When sold, the reclaim solder still contains all previous contaminants.  Metallic Resources does not sell reclaim solder.  Through the use of state-of-the-art refining technology, Metallic Resources converts a combination of impure virgin-grade solder, solder dross, solder paste, contaminated pot metal, and other materials into the highest grade of tin, lead, and lead-free solder.
Although the name suggests otherwise, virgin-grade solder is not free of contaminants, nor is it entirely pure.  Virgin-grade solder manufacturers simply take virgin-grade tin, lead and other elements, then mix them together into the desired alloy – with both known and unknown amounts of metallic and non-metallic contaminants.  Although many solder manufacturers may claim to meet the IPC J-STD-006 for electronic solder alloys, that standard is wide in latitude.  In short, virgin-grade solder is anything but pure.
So why does electrolytic solder outperform reclaim and virgin-grade solder?  Because the purity level is simply unmatched. To get there, Metallic Resources utilizes proprietary electrolytic-refining techniques. We start by melting and mixing impure virgin-grade solder, solder dross, solder paste, contaminated pot metal, and other materials together into an impure and contaminated anode. The tin/lead or tin anode is then placed next to a 99.99% pure cathode sheet and an electric current is run through the electrolytic bath. The impure and contaminated anode depletes into the bath.  Only the pure desired alloy grows on the cathode sheet, while all other contaminants, metallic and non-metallic, precipitate out into the bottom of the tank as a sludge.  The resulting tin/lead or tin cathode metal is 99.99% pure. This highly pure metal is then adjusted based on the desired alloy. Unlike reclaim and virgin-grade solders, this process results in less impurities and assures batch-to-batch consistency.
Through the electrolytic process, Metallic Resources can obtain triple zeroes of purity, whereas J-STD-006 only calls for electronic grade solder having single or double zero purity.  With less contaminants, electrolytic solder from Metallic Resources features lower viscosity, lower surface tension, and greater fluidity, all resulting in:

  • Brighter, Shinier Solder Joints
  • Superior Wetting and Wicking
  • Fewer Defects
  • Significant Reductions in Rework

The electrolytic process removes metallic and non-metallic impurities often found in “virgin metals” and reclaimed solders to provide purer tin and tin/lead solder. This purity results in a smaller crystalline structure which exhibits a shinier, more brilliant solder appearance.
Beyond these defining characteristics, electrolytic solder from Metallic Resources also yields less dross and is more sustainable than the competition.  A solder that is lower in viscosity and surface tension will flow more smoothly and cause less turbulence. What this means is less dross generation compared to all other non-electrolytic and virgin-grade solder.  Less dross means less waste, resulting in more soldered joints per pound of solder and greater cost-effectiveness.  On top of this, the generated dross has less solder content for minimal solder loss, more efficient product usage, and greater economy. Finally, solder pots using electrolytic solder can be operated at lower temperatures to provide energy savings, extended pot life, reduced thermal stress, and reduced potential of contamination.