Soldering stainless steel stranded wire to platinum foil [SOLVED] - Page 1
Forum section: electronics / projects

author: jp1390
author_rank: Contributor
timestamp: June 01, 2017, 05:12:13 am
content: Hello,I am fabricating electrodes using small (2mm x 2mm) platinum foil contacts attached to PFA-insulated stainless steel stranded wire. Currently I have been using a cold-solder epoxy technique with some success, but I was curious about using heat to make the connection.I am curious if anyone has experience soldering either of these metals and/or if you have any tips for temperature range, flux, and solder type.Thank you!

author: tautech
author_rank: Super Contributor
timestamp: June 01, 2017, 05:33:57 am
content: The first thing that comes to mind are Easyflo silver solders:http://www.silfos.com/products/catalog/Easy-Flo-45-orderby0-p-1-c-67.htmlBut looking a little harder from a similar family of product and from the same manufacturer:http://www.silfos.com/products/catalog/Silvaloy-Braze-orderby0-p-1-c-35.html

author: oldway
author_rank: Super Contributor
timestamp: June 01, 2017, 05:43:31 am
content: Spot welding is perhaps possible acording to the thickness of the platinum foil.Brazing with BAg-1 through 7 filler metals is another possibilitytemperature range:BAg-1 (45% Ag) 1145-1400°F

author: noidea
author_rank: Unknown
timestamp: June 01, 2017, 05:47:11 am
content: Soldering to Stainless steel is problematic at the best of times, I've never soldered to platinum before but have silver soldered / brazed stainless many times. The basic rule of thumb is the more silver the better and don't overheat the joint too much I have had best results with this stuff.http://www.harrisproductsgroup.com/en/Products/Alloys/Brazing/High-Silver/Safety-Silv-56.aspxYou may be better off asking your question on a jewelry makers forum or a metallurgist, as they may have more experience working with precious metals

author: oldway
author_rank: Super Contributor
timestamp: June 01, 2017, 06:26:44 am
content: For silver brazing, use a propan/oxygen mini torch like the Gloor Minicro.http://shop.gloor.ch/FR/minicro

author: Someone
author_rank: Super Contributor
timestamp: June 02, 2017, 01:39:18 am
content: Quote from: noidea on June 01, 2017, 05:47:11 amPlatinum solders beautifully with normal Pb or Ag solders.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: June 02, 2017, 07:44:05 am
content: If you're on the east coast of our country I'd gladly supply some Stay-Silv 56 and some Stay-Silv white flux if you'd like to try it. I've used the combination many times with stainless steel with very good success. The main other uses I've had for it are with HSS, high carbon steels and making thermocouples. Mostly I've used a plain MAPP torch to heat the work pieces though for very small things I've used a cheap butane torch. I've also used an electric arc with medium success.

author: jp1390
author_rank: Contributor
timestamp: July 29, 2017, 08:31:35 pm
content: Thanks Paul, I didn't see this in time...I was able to find a product that worked for my purpose.Superior #71 Stainless Steel Flux worked great and can be purchased from SRA Soldering Products:http://www.sra-solder.com/flux-71-flux-high-activity-for-stainless-steel-4-ozSuperior RubyFluid Stainless Steel Flux also seemed to work:http://www.sra-solder.com/rubyfluid-stainless-steelI transferred each flux solution into their own flux bottle applicators with needle tip. It only required a few drops on the stranded wire to take effect. I was then able to tin the bare wire with either leaded or lead-free solder with no issue and a bit of a nice hissing sound. As per the product recommendations, I agitated the freshly tinned stainless steel wires in hot tap water for 3-5 minutes to remove any residues. Soldering to other metals was then a breeze. I would recommend using gloves with this flux.I preferred the #71 as it was a more aggressive flux and I had better results when tinning.Hope this helps someone down the line.

author: RoGeorge
author_rank: Super Contributor
timestamp: July 29, 2017, 08:49:36 pm
content: Just in case there is no proper flux available, a trick that works well when soldering on Aluminum is to place a big drop of motor oil or cooking oil, scratch the surface a little, then solder under the oil. The oil keeps the Oxygen away during heating, so the solder sticks very well. I don't know if it will work with stainless steel too, but worth a try. Use an old spare as a soldering tip, because it will be very hard to clean the oil from the tip.