Solder again

[Christer]

There has been some threads on solder, but it has mostly been
about the possible sonic benefits of silver solder and not much
has come up on other properties of various alloys. I did some
reading on this which I posted in the thread "the sound of silver
alloys" but did not get much reaction, so I'll make a new attempt
at getting some opinions on solders from the non-sonic
perspective.

I cannot see any reason not to use a eutectic alloy, ie. one that
has a sharp phase transition from liquid to solid when cooling
since this minimizes the risk of cold joints (it is claimed to be
better sonically by George Cardas). For instance, the common
60/40 solder is not eutectic, but 63/37 is. Yet, there seems to
be more 60/40 solder in the suppliers catlogues and it seems
used a lot. Why? This puzzles me, since it seems more sensible
to use 63/37.

Supposing we decice on a eutectic solder, should we go for a
silver solder? Should we go lead free? Adding silver to the alloy
increases the joints strength against shearing from thermal
stress. When soldering silver or silver-coated parts it also
prevents the silver from migrating into the joint. Seems to be
nothing speaking against it (though, when it comes to sonics
there are different opinions). Lead free solder is good for the
environment but is it as good as lead-based solder when it
comes to electrical and mechanical properties? The argument
that lead-free solder should be better for our own health when
soldering seems not to hold. There will be no lead particles in
the smoke unless we heat the solder to at least 500 deg. C.
(The flux can produce toxic particles/gases, though, but that
applies to lead-base and lead-free solders alike). Finally,
copper is sometimes included in the alloy. It may have a similar
effect as silver of preventing migration of copper into the joint,
but it is unclear if this can happen. The only claimed reason for
copper I have found is that it prolonges the life of the tip of
the soldering tool.

And I almost forgot, melting point is also a factor, of course,
since it differs between the alloys. I suppose a low melting point
is preferrable, especially for surface-mount components.

I haven't cared about the solder before, but my old roll is
most probably 60/40 which I bought cheaply somewhere. It
seems to make sense to replace it with a eutectic solder, but
which one.?

Some common eutectic alloys and their melting points are:

63% Sn 37% Pb 183 deg. C
62% Sn 36% Pb 2% Ag 179 deg. C
96.5% Sn 3.5% Ag 221 deg. C
95.5% Sn 3.8% Ag 0.7% Cu 217 deg. C

As can be seen, the lead-free alternatives have a higher
melting point than lead-based alloys. I am thus considering
the second alternative, 62%Sn 36% Pb 2% Ag. Then comes
the choice of fluxes too. I can choose from two such alloys
locally Multicore X-39B with. 2 cores of unspeccified flux and
Multicore LMP w. 5 cores of Ersin 362 flux. The latter is much
more expensive. Neither can be bought in small quantities,
unfortunately, so price is an issue.

Opinions? Experiences? Any reasons not to go for this
alloy?

[Christer]

Maybe I am impatient, but ar there really neither opinions nor
experiences about this? If somebody asks how solders sound
there are immediately a million answers (OK, not quite a
million ), and when I asked about soldering stations there
was a lot of testimonies praising Weller, Pace, Hakko and Metcal.
I would think the boring properties of the solder are also quite
important, don't you?

[UrSv]

Hi Christer,

I was also thinking for a while before switching solder as I, like most people I suspect, had been using normal 60/40. I choose the 62Sn/36Pb/2Ag DLMP22 from MultiCore. I choose it because 1. it had silver and 2. it had low melting point. I did not trust myself to use HMP as I was sure I'd ruin some PCBs with it sooner or later. I still use 60/40 for normal power supply work where no silver is involved in wires ect.

Price issues. I also checked the prices and it seems the price for the 0.71 mm is much lower than the thinner ones so I choose that one. For 250g rolls 0.71 is SEK 310, 0.56 mm is SEK 370 and 0.46 mm is SEK 540 at Farnell. Actually I bought mine in Switzerland where VAT is low so I paid CHF 40 for it which is SEK 240 including VAT. That was acceptable for me.

It solder well and is as easy as the 60/40. I'm happy with it but I can't say anything about sonics as I haven't tested it for that.

/UrSv

The solder is Farnell product 419540.

[mrfeedback]

Hi Christer, the LMP 60/38/2 is the solder I say that I do not like.
Sure it tins and wets very nicely and gives very nice shiny joints.
My experience is on first listen that it gives a brighter and more detailed sound, but on extended listening I find the mids and highs to be exaggerated and false.
Long term listening becomes fatigueing.
OTOH I find 96S (96Tin/4 Silver) much the opposite.
On first listen sonics may seem a little dulled, but on extended and long term listening, I find the result to be rather more pleasant.
The initially apparent dulling of mids and highs turns to quieter and nicer detail, and to my ear more perfect pitch harmonically correct.
96S is significantly more conductive than LMP or standard solder, but I forget how much.
This is part of the equation, but not all I feel.
It seems that it is just a fact that different matals sound different, and alloys have further effects - sort of like an intermodulation effect.

Eric.

[AudioFreak]

I'm switching to Multicore Ecosol (95.5% Sn 3.8% Ag 0.7% Cu with a synthetic flux) as of next week. I will be using this alot over the next month. This stuff costs a fortune $55 Australian / 250 grams (US$25 for just over 1/2 lb.). I'll let you know what I think of it.

[Peter Daniel]

I never compared the sound of different alloys and I'm using Cardas solder only, but I found this post before and member known as Scorpion shares his opinion on solder: New dual-mono power amp

[mrfeedback]

I have not tried that alloy yet - that would be my next choice, given my experience with Savbit (2%Cu).
have you looked up Multicore wholesalers in the yellow pages ?.
That's where I by my solders from, and much cheaper than retail stores, if they stock it.
We are interested to hear your sonics reports and findings.

Eric.

[schmad]

Christer,

Practically speaking -- think about all the audio equipment that is produced that goes through reflow soldering. The equipment that studios use to do recording, etc. For the great majority, they use plain old 63/37 paste. Eutectic solder or otherwise, it's just not going to make any appreciable difference. As far as flux goes, RMA is best IMO (cleans leads the best), but also the messiest to clean up. No clean fluxes (esp. some of the newer ones made from lemon extract) don't do a very good job of cleaning, but also don't require any cleanup.

[Christer]

UrSv,

I also looked at Farnell after reading your comments, and it seems
that for once they are cheaper than Elfa, and quite a lot cheaper.
Still, with freight it may not be worth it for a roll of tin only, and
they are quite expensive on most other things. Elfas price on
the LMP is horrendous so I'd probably consider the X-39B
instead which differs only in the amount and type of flux.


Eric,

Good to hear that the LMP works fine to solder with. As for the
sonics, I appreciate such comments too, although this thread
was mainly intended to discuss the other aspects. I will take
you opinions into consideration, but sonic impression will always
be subjective, so unless I take the cost of buying several solders
to compare myself I'll probably not give that much weigth to
this. Apart from sonics, I had almost decided to buy the type
of tin you recommend (at least the same alloy) since it is lead
free, eutectic and contains silver. However, I then took the
melting points into consideration and am not so sure anymore
that lead free is so good. Well, there are good lead-free solders
with low melting points, but only for industrial use, it seems.


Scmad,

As I pointed out, I was mainly after other aspects on solders than
the sonic ones and, yes, I think it makes a difference. A eutectic
solder will decrease the risk for cold joints, a low melting point
is more component-friendly, especially for SMT components.
Proably there are more important aspects, and trade-offs to
consider, which is why I ask for opinons and experiences.

[AudioFreak]

Originally posted by mrfeedback
Have you looked up Multicore wholesalers in the yellow pages ?. That's where I by my solders from, and much cheaper than retail stores, if they stock it.

I've done some checking and this particular product is only available in Australia thru Farnell as they import it from the UK. Multicore (now part of Loctite) currently has no plans to introduce this product into Australia but have said that they will review this situation from time to time. So, at present, I'm stuck paying $55 / 250g.