G
GCiTech
Does anyone know how to confirm if the solder used contains silver? Is there a solution that would change color in the presence of silver? If so, what is the name of the solution?
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Welcome to the Cove.
Are you referring to solder that's been melted and applied to an assembly, or some form of unused solder?
G
GCiTech
We are referring to melted and applied to an assembly
X-ray fluorescence comes to mind. XRF machines are fairly common in plating shops these days, especially those where precious-metal plating is done.
I am keen to know why you need this checked on the applied solder.
If you suspect solder performance for lack of silver, it is better to check back with the manufacturer with the batch details for his batch assay report, or approach a third party analytical lab with the Ag solder paste for an assay for silver content.
Traditionally,
Nitric acid of known concentration is used to give an idea on the percentage of silver in jewellery but with percentages as low as less than 5% in solder, I am not sure what color/signal would it give you.
J
Jeff Frost
You might check IPC-TM-650 to see if there is a test method for silver content of solder.
Dr. L. Ramakrishnan
Moderator
Please refer to "Qualitative Analysis of Group I cations" in any Analytical Chemistry Book. The procedure is simple. Dissolve a small quantity of the solder in dilute nitric acid in a glass beaker, by heating it on a hotplate slowly; tin will precipitate as tin oxide. The filtrate contains lead (if it is a lead containing solder) and silver (if any). Add dilute Hydrochloric acid to the filtrate; both lead and silver will precipitate. Heat the solution - lead chloride will dissolve; if some precipitate remains it is an indication of silver chloride. Filter and add ammonia to the precipitate; if it is silver chloride, the precipitate will dissolve. You can get back the precipitate by adding hydrochloric acid to this solution if silver is present. For details see any text book on qualitative inorganic analysis.
