Attached are the latest datasheets for the Black (2758) and Gray (2760) body binding posts designed by Low Thermal. The company now offers new insert colours (e.g., black, brown, red, yellow, green, blue, violet, gray, and white)! The other day, I spoke to a representative for Low Thermal over the phone. Let's call him Dave. Here is some information before I forget:
At the moment, the company is working toward domestic manufacturing within the USA due to the material shortages during the pandemic and the reliance on foreign manufacturing. Low Thermal is also very concerned about lead (Pb) content in copper grades from China and Taiwan. They have a special source for copper that does not have as many impurities because the copper has not yet been recycled. Another aspect is the plastic injection moulding requirements; they want quality control on dimensionality and electrical performance which is difficult to accomplish when outsourcing the work. They anticipate that their stock should be available again sometime after September.
The gold coating process that Low Thermal applies does not use nickel plating as a buffer material to prevent Cu-Au diffusion. This direct gold depositing step is unique and is an advantage over its competitors.
1) The company uses certified C145 as the substrate to balance machinability and electrical performance. Higher purity grades like C110 and C101 are too soft for machining and cannot achieve the desired tight tolerances compared to alloyed tellerium (C145) or beryllium (C175) grades.
2) A pure copper layer is applied to the surface and is referred to as "striked copper." I do not know how they apply the copper to the substrate. I suspect that it is somehow very dense (i.e., limited vacancies) to prevent substitutional diffusion. If anyone cares to elaborate, that would be great.
3) Gold is then electrolytically deposited onto the pure copper layer. Over the 12 years that they have been manufacturing these products, they have reduced the gold layer from 30 to 10 micro-inches. This thickness is much greater than other candidates. Dave argues that the thickness of the gold is sufficient to prevent loss of performance over the expected lifetime. I assume the lifespan of the coating is on the order of decades with normal use.
The same plating process described above for the posts is applied to the gold-plated forks that they offer. The only difference is that they use half-hardened C110 as the substrate because it is softer than the binding post substrate and will not wear down the gold-plated layer as easily. Note that C145 is a much harder substrate than C110 because of the tellurium alloying element. The rationale is that forks are cheaper and more convenient to replace whereas binding posts are not.
Hope this helps. If I find out any more details, I will post them here.