"Tinned" resistor leads - UK Vintage Radio Repair and Restoration Discussion Forum

John_BS · 12th Mar 2023, 2:31 pm

Does anyone know if the resistors typically used in the 80's & 90's had leads which were literally tinned, or were they a 60:40 or a similar alloy?

John

Leon Crampin · 12th Mar 2023, 6:02 pm

It varies with the maker. For high volume automotive applications, I specified strict solderability requirements, together with stock rotation and use-by dates. Military standards as usual were useless - so I devised my own.

As an example, vitreous enamelled wire wound resistors were not acceptable, as the leads would oxidise after enamel firing. The maker would sand blast the leads, and then dip them into a solder pot prior to dispatch. After they failed my solderability test, I visited the factory. The sand blasting process was crude and incomplete.

Philips power metal oxide resistors with tin/lead coated leads were therefore specified for my high volume application.

Leon.

12th Mar 2023, 2:31 pm	#1
John_BS Octode Join Date: Dec 2008 Location: Wincanton, Somerset, UK. Posts: 1,780	"Tinned" resistor leads Does anyone know if the resistors typically used in the 80's & 90's had leads which were literally tinned, or were they a 60:40 or a similar alloy? John

12th Mar 2023, 6:02 pm	#2
Leon Crampin Octode Join Date: Nov 2005 Location: Surrey, UK. Posts: 1,870	Re: "Tinned" resistor leads It varies with the maker. For high volume automotive applications, I specified strict solderability requirements, together with stock rotation and use-by dates. Military standards as usual were useless - so I devised my own. As an example, vitreous enamelled wire wound resistors were not acceptable, as the leads would oxidise after enamel firing. The maker would sand blast the leads, and then dip them into a solder pot prior to dispatch. After they failed my solderability test, I visited the factory. The sand blasting process was crude and incomplete. Philips power metal oxide resistors with tin/lead coated leads were therefore specified for my high volume application. Leon.