Question about solder

[8009514]

Been talking to a pal about soldering. He advocates the use of silver solder for anything to do with electronics. Well I've been in electronics now for 30 years and have never used it myself. But, the chats I've had with him have raised a couple of questions which, maybe, forum members can help with.

1. Does the iron temperature need to be much hotter in order for silver solder to flow properly? (I don't really see it myself as silver content is probably only 2%)

2. Will the use of silver solder make any difference in a hifi environment? ( Bearing in mind that only 2% is silver, the rest being normal tin and lead constituents.)

Any experts out there who would care to venture an opinion?

 

[True Blue]

Below are a couple of useful paragraphs that answer your questions:- Through an interent search ( I am NOT an expert)

"On July 1, 2006 the European Union Waste Electrical and Electronic Equipment Directive (WEEE) and Restriction of Hazardous Substances Directive (RoHS) came into effect prohibiting the intentional addition of lead to most consumer electronics produced in the EU. California recently adopted a RoHS law[3] and China has a version as well. Manufacturers in the U.S. may receive tax benefits by reducing the use of lead-based solder. Lead-free solders in commercial use may contain tin, copper, silver, bismuth, indium, zinc, antimony, and traces of other metals. Most lead-free replacements for conventional Sn60/Pb40 and Sn63/Pb37 solder have melting points from 5-20 øC higher"

"SnAg3.0Cu0.5, tin with 3% silver and 0.5% copper, has a melting point of 217 to 220 øC and is predominantly used in Japan. It is the JEITA recommended alloy for wave and reflow soldering, with alternatives SnCu for wave and SnAg and SnZnBi for reflow soldering.

SnAg3.5Cu0.7 is another commonly used alloy, with melting point of 217-218 øC.

SnAg3.5Cu0.9, with melting point of 217 øC, is determined by NIST to be truly eutectic.

SnAg3.8Cu0.7, with melting point 217-218 øC, is preferred by the European IDEALS consortium for reflow soldering.

SnAg3.8Cu0.7Sb0.25 is preferred by the European IDEALS consortium for wave soldering.

SnAg3.9Cu0.6, with melting point 217-223 øC, is recommended by the US NEMI consortium for reflow soldering.

SnCu0.7, with melting point of 227 øC, is a cheap alternative for wave soldering, recommended by the US NEMI consortium.

SnZn9, with melting point of 199 øC, is a cheaper alloy but is prone to corrosion and oxidation.

SnZn8Bi3, with melting point of 191-198 øC, is also prone to corrosion and oxidation due to its zinc content.

SnSb5, tin with 5% of antimony, is the US plumbing industry standard. Its melting point is 232-240 øC. It displays good resistance to thermal fatigue and good shear strength.

SnAg2.5Cu0.8Sb0.5 melts at 217-225 øC and is patented by AIM alliance.

SnIn8.0Ag3.5Bi0.5 melts at 197 to 208 øC and is patented by Matsushita/Panasonic.

SnBi57Ag1 melts at 137-139 øC and is patented by Motorola.

SnBi58 melts at 138 øC.
* SnIn52 melts at 118 øC and is suitable for the cases where low-temperature soldering is needed.

Different elements serve different roles in the solder alloy:

Silver provides mechanical strength, but has worse ductility than lead. In absence of lead, it improves resistance to fatigue from thermal cycles.

Copper lowers the melting point, improves resistance to thermal cycle fatigue, and improves wetting properties of the molten solder. It also slows down the rate of dissolution of copper from the board and part leads in the liquid solder.

Bismuth significantly lowers the melting point and improves wettability. In presence of sufficient lead and tin, bismuth forms crystals of Sn16Pb32Bi52 with melting point of only 95 øC, which diffuses along the grain boundaries and may cause a joint failure at relatively low temperatures. A high-power part pre-tinned with an alloy of lead can therefore desolder under load when soldered with a bismuth-containing solder.

Indium lowers the melting point and improves ductility. In presence of lead it forms a ternary compound that undergoes phase change at 114 øC.
* Zinc lowers the melting point and is low-cost. However it is highly susceptible to corrosion and oxidation in air, therefore zinc-containing alloys are unsuitable for some purposes, e.g. wave soldering, and zinc-containing solder pastes have shorter shelf life than zinc-free.
* Antimony is added to increase strength without affecting wettability."

 

[nads]

Mmm silver solder and electronics.

dont think the electronics would last the process.

Silver solder is often used for joining steel parts (and jewellery amongst other things).

melting points from 600-800 deg. C

I think someone may be getting their terms confused.

 

[Anonymous]

My Quad 405 amp was rebuilt and the various connections and components were soldered using silver-based solder. Pretty common in audio circles I think. This ain't 100% silver though!

 

[aliEnRIK]

I use audio grade silver solder. You have to get it hotter than normal solder but I dont have any problems personally

 

[The_Lhc]

aliEnRIK:I use audio grade silver solder. You have to get it hotter than normal solder but I dont have any problems personally

Rather you than me. If my time as an electronics engineering apprentice taught me anything (and it didn't!), it's don't go anywhere near your own gear with a soldering iron!

 

[nads]

so there are 2 different types of silver soldering?

Fabrication and Electronics? I only know of the Fabrication version.

 

[aliEnRIK]

the_lhc:
aliEnRIK:I use audio grade silver solder. You have to get it hotter than normal solder but I dont have any problems personally

Rather you than me. If my time as an electronics engineering apprentice taught me anything (and it didn't!), it's don't go anywhere near your own gear with a soldering iron!

Erm ~ wires mate. Im not soldering circuit boards or anything of that nature

 

[PJPro]

I used an tin, lead and silver solder for my DIY Headphone Amp. I found that it took more heat to melt and when it did it melted all of a sudden.

For the Graham Slee Nova Kit I was sufficiently worried about the difficulty of soldering with a silver alloy that I stumped up £27 to get a Tin / Lead mix at 63% / 37%. This was easier to melt and melted a little more slowly.

Please note that I can only be regarded as a rank amatuer at these tings. I'm sure that a competent solderer wouldn't have a problem.

I can point you to a page where the various merits of the different solders are discussed....and the site is generally a good source of information. Please find it here.

I don't know whether silver solder sounds better. But you do notice the odd high end brand touting the fact that silver solder has been used.

 

[Anonymous]

As I am a manufacturer I have to use the new silver/tin alloy solder but I don't really like using it as much as the lead/tin stuff. It doesn't seem to flow nearly as well. The temperature on my soldering station has to be set higher for best results.

 

[Anonymous]

I use WBT 4% silver solder. There are at least two versions, one with lead and one without. I prefer the version withÿlead as it's much easier to work with and makes for less brittle joints.

 

[idc]

A friend who is an engineer who develops gyroscopes and lazers told me that the problem with lead free solder is 'tin whiskers' risking shorts. He described the move away from lead free solder as a reliabilty time bomb. Apparently Swatch came out and admitted that they could not reliably manufacture without lead based solder and have got an exemption.