Stew,

The material you saw labelled "silver solder" is in no way equivalent to "real" silver solder as used for silver brazing at 600 deg C plus. It is just a lead free soft solder which has a tiny amount of silver added to give it the desired properties.

David

Stew its probably similar to the Harris "staybrite" where the silver is added to compensate for the lead being removed, they give strengths on their site. Click the resorses tab and then spec

**LINK**

Edited By JasonB on 21/03/2013 13:38:56

Here (Canada) the lead free solder was mandated for potable water plumbing. I think it's 95% tin 5% antimony. As far as I know ordinary 50/50 lead-tin is still ok for electrical and other work. I've seen "silver solder" 95% tin etc advertised but as far as I'm concerned it is deceptive advertising as real silver solder has a definite set of uses and cannot be replaced by the 95% tin stuff.

Ken

Tin/lead solder is still available from professional electronics distributors. I don't think there's a ban on its use per se; what is banned is use in equipment put on sale within the EU after a given date. As always there are exceptions, including large scale fixed industrial equipment, exclusively military equipment and some medical devices.

To be pedantic the exemptions for medical devices were removed in 2011, but there are moratoriums in place for 3 or 5 years depending upon the precise use of the equipment. You wouldn't want a duff joint in your pacemaker!

Regards,

Andrew

Hi Stew,

The informaton you seek is basically unavailable because joint strength is not only dependent on the bulk strength of the alloy (which may be available) but more importantly on how and where it is used. A manufacturer or supplier has no control on these factors and therefore cannot quote any figures.

For instance the strength of a butt joint in tension is dependent entirely on the bulk strength of the filler metal – assuming that is higher than the strength of the parent material! Although soft and silver solders are sometimes used in this manner – they are not intended to be so.

These fillers metals should be used such that the joint is designed to operate in shear ie using capillary attraction to make the joint. Even then there are considerations.

Joint gap – narrow gaps = stronger joints

joint length – too long = possibility of voids / too short = insufficient area to carry the load

degree of penetration – dependent on heating technique

joint design

fluxing

No supplier can control these factors hence there are no figures. The only solution is for the user "to suck it and see". If it gives you the result you want then use it. Generally speaking there is a technical reason why silver solder is used in place of the cheaper soft solders.

eg its melting temperature,

corrosion resistance

potentially higher joint strength

ability to join dissimilar metals etc

An F1 car can reach speeds of 200mph(?) but not with a 15 stone driver, roof rack, and pulling a caravan. But that is not what it s designed for – hence the ford escort et al.

Finally, when selecting silver solders, the last consideration is joint strengh. Used properly they will all produce joints stronger than the parent metal.

keith

I'm not sure anyone knows if the actual amount of lead was a hazard.

I don't know, having hard water was agood protection, once the pipes furred up.

There was a statistically significant shortfall in kid's educational attainment clustered around the M6 and spaghetti junction in the days before lead-free petrol.

Neil

As jo says about difficulties with lead free solder in avionics, I can see lives lost because of this.

The local second hand shop here often has tin lead solder, and I'm getting quite a collection of it, two reasons, one it could get difficult to obtain, two, they sell it at a fraction of the normal retail price.

Ian S C