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doyall
10-30-2006, 05:42 PM
Anybody got any thoughts about the relative advantages/merits/etc. of liquid tin (if it can be purchased by an individual) and the just-add-water type of tin such as that sold by Parts Express? Can either of them be used to tin wire before crimping or are they only good for doing boards? Any brands better than others?

Thom
10-30-2006, 07:53 PM
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doyall
10-30-2006, 08:20 PM
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http://www.circuitspecialists.com/products/8275.jpg (http://www.circuitspecialists.com/products/full/8275.jpg)

versus


TINNIT TIN PLATE TinnitTM will plate a copper clad board with a bright tin plate approximately .0004" thick. Enhances solderability. Supplied as a dry concentrate, just add water to make one pint of solution that will plate up to 600 sq. inches of copper. After being mixed, solution has approximately a 2 month life. http://www.partsexpress.com/images/nothing.gif

Robh3606
10-30-2006, 08:44 PM
Can either of them be used to tin wire before crimping or are they only good for doing boards?

Why would you Tin before crimping???

Rob:)

Ducatista47
10-30-2006, 09:19 PM
Why would you Tin before crimping???

Rob:)

Silver solder.

Clark in Peoria

Zilch
10-30-2006, 09:33 PM
The "Tin before crimping," first of my quotes, comes from experiencing stranded wires falling out of crimp-on connectors, a clear indication of a marginal connection.

Unless done precisely with a proper circumferential crimping tool, the connections are unreliable. The individual strands of copper wire are also more subject to corrosion over time.

Thus, I always "tin" the lead ends, i.e., apply solder to them, to make a solid wire end for insertion into a connector before crimping.

Same with all of the speaker cable ends floating around here for insertion into binding posts and screw terminals - they're all "tinned"....

Ducatista47
10-30-2006, 10:07 PM
Good thoughts, Zilch. When my late Father taught me to use a soldering iron when I was five, I think tinning wire ends was the first thing he showed me. To this day I tend to tin a wire or cable as soon as I cut it to length or even strip an end. It just doesn't seem right to let bright copper turn dull in the atmosphere.

I know that some audio connectors should not be used with solder, but I solve that by using predominately spade lugs, the largest that will fit.

Clark

Ian Mackenzie
10-31-2006, 02:59 AM
You would be surprised at the insertion losses mutiple crimp/spade connections introduce. Why you digest that ask yourself what is the male and female spade made out of and how is it finished??

Clean and tin both surfaces and apply liberal heat to the joint. Wire wap if desired.

doyall
10-31-2006, 07:19 AM
OK, if I can use solder to "tin" before crimping and silver solder is preferrable, does one use silver solder paste or silver solder wire? If wire, 4% or 2% silver content?

And relative to the material from which spade and ring terminals are constructed, I take it tinned copper might be acceptable. Is there any "best" brand and if so, where can I find them. The only ones I can find with the construction components listed as such are sold for marine use. I can't help but think that the everyday ones I get at the hardware store (http://www.partsexpress.com/images/095-230t.jpg (http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=095-230)) are aluminum. Would gold plated ones sold for automotive use be better?

Ducatista47
10-31-2006, 07:33 AM
I use a high purity (or oxygen "free") copper lugs. My hi-fi shop has a variety of sizes loose in a plastic tray organizer, I'll have to ask what brand. It makes sense to me to use lugs as good as the wire you connect them to, so that might inform your decision.

For solder, again I use what they carry in the shop - what I can buy here! I've seen it on the web, but for more money. It is WBT, 4% fine silver, from Essen, Germany. You generally can't go wrong with German technology and craftsmanship. It is a slim wire, 0.8mm, that disappears with frightening speed when being applied to a joint.

Sometimes I wonder if 4% silver can make any difference to conductivity. Perhaps I had more money than brains the day I bought it. ;)

Edit: Ever notice how much you can pay for an RCA connector? The designs and materials keep coming, all to overcome the fact that RCA plugs were never designed for critical audio use. In two words, they stink. That's why I use lugs. Large contact area, great materials available, easy to clean the surfaces, indestructible, tighten to your heart's content. The contact does not rely on the complex yet dubious design and execution of the RCA's circular crimp design, which crimps less with time and use anyway. RCA's are also inherently weak mechanically, as there are insulators between the metal parts. It is a lot cheaper to manufacture a great lug than a more complex design of termination, which is to say all the other systems.

The one good thing about the 5235 xover is the use of terminal strips instead of RCA inputs. Too bad there is probably steel in the line somewhere. Even high end gear seems to have RCA inputs.

Clark in Peoria

Robh3606
10-31-2006, 07:41 AM
The "Tin before crimping," first of my quotes, comes from experiencing stranded wires falling out of crimp-on connectors, a clear indication of a marginal connection.

Hello Zilch

That's why you need the correct tooling. I have tried crimps using the inexpensive tools and they simply are not that reliable. They don't fixture the spades so you crimp the correct areas and there is no stop to prevent over crimping where you actually cut the wires. You really are not supposed to tin wires that are crimped. Done correctly it's gas tight connection. Me I solder no issues at all that way.

Rob:)

Ducatista47
10-31-2006, 07:51 AM
Hello Zilch

Done correctly it's gas tight connection.
Rob:)
For better or worse, I use Kimber wire. When you are finished joining all the strands I doubt the bundle is a perfect standard gauge. I can assure you that forming it into a perfectly round entity is usually beyond me! Don't the lug and crimp tool have to be an exact match with the wire gauge to form a gas tight connection?

Clark

Zilch
10-31-2006, 10:08 AM
The gas-tight connection occurs at the point of contact between the connector and the individual strands, where the pressure between them is high.

Ever see a wirewrap connection appear to be "welded" at the post corners? That's a gas-tignt connection.

I'm with Rob. I just can't do it to my satisfaction with simple crimp tools, and end up soldering typically. The tinning makes THAT an easy go.... :D

Robh3606
10-31-2006, 10:25 AM
Hello Clark

If you look at most crimped connectors the barrels that accept the stranded wire are set-up to use a predetermined wire gage range of say 18-22 gage as an example. That way when you use the crimping tool for that barrel size it compresses the connector around the wire and you end up with a gas tight connection. Most crimping tools only compress the middle portion of the barrel so the wire is crimped only in this area. Most of the wire gage ranges for the crimped barrels are only a couple of gages. We may end up using 2-3 barrel sizes and multiple crimping tools in a single connector depending on the wire gages used in the harness where I work. We actually do destruct pull test samples of crimps and the wire is the what fails. When done right they make a very strong and reliable connection.

Rob:)

Thom
10-31-2006, 12:39 PM
OK this must be simular to what some people paint on the joining sections of copper buss only that is usually silver. As to solder or crimp. Theoreticly you can get the best connection with a crimp,( but I like to solder, unless you're on the clock.) However the wire, connector and tool should all be made to be used together. How often does that happen? As soon as your conector says wire gage xx to xx your sunk. If you can actualy get the strands tinned that probably makes for a better crimp. We have already given up on that ideal crimp. If you open an expensive piece of gear and find crimps,in the manufacturing enviroment they may very well be using what it takes to make ideal (thats ideal with a small i)crimps. Tinning the entire group of strands before crimping is a bad idea. It keeps the conductor from flowing properly into the crimp. Thomas & Betts and Panduit are a couple of the better brands but they make different levels of quality also. It used to be that if the insulator was nylon as opposed to pvc that was a quality connector. Not anymore. Solid wire is very difficult to make good crimps to and tinning a lead is definitly in that direction. If you have to be careful when crimping to make sure the conmnector krimps correctly insted of rolling in the tool and one part overlapping the other that is a junk terminal. Reps from most of the better companys have sampler crimped connections that have been cut across and you can't see the individual strands. But most field crimp connections are not like that. Probably your best connection would be to crimp with a hi temp connector and then solder. If you dont use a hi temp connector there is some chance that when you are through soldering the crimp will have lost it's strength, but you will still have a solder connection. If your going to solder, make note of the temperature. Don't solder in light fixtures, to power resisters, etc. I would keep anything with a water base away from stranded wire. The principle has to be that the tin is extremly fine and when the water goes away you still have tin. Well with capillary action you will probably get water places you don't get tin.

The really good connections are more often refered to as compression than crimp.

In summation: don't use anything that has water or any thing else that may damage copper near the end of stranded wire. Capillary action will carry the liquid well up into the wire where it will not dry but will damage the wire.

Unless you're using a lot of them, are in a bad enviroment (I don't mean high crime) or your current to voltage ratio is high a pretty good crimp is probably good enough.

Ducatista47
10-31-2006, 07:28 PM
Thom, I guess I follow your wisdom here. The lugs I use have a long, thick wire channel. They can be crimped along a quarter inch or better length, but it ends up shaped like the Everest DD66000 from above, not a tube. My hi-fi shop guys told me not to tin before crimping to the copper lugs, so I crimp and then use the mentioned capillary action to flow silver solder through the entire crimp, wire, lug tube and all. Since these lugs have separate insulator sleves, as much heat as is necessary can be applied. Result: a solid blend of copper wire, copper lug and silver solder. Mechanically tough, solid in fact, and all great conductor with nill voids. The Fluke meter confirms it has the properties of a solid wire.:)

Clark

Thom
10-31-2006, 08:12 PM
What you end up with is a joint electricaly as good as your soldering and the crimp takes care of always have a mechanical connection befor you solder. Important:stranded wire totally inactive flux otherwise someday the flux that helped make the job so nice will destroy it.

Steve Schell
11-01-2006, 02:23 AM
It has been a while since I did much soldering, but I recall reading that a good practice is to make a secure mechanical joint first, then flow in solder second to seal it from the atmosphere. Neither tin nor lead would seem to be very good conductors on their own, but they do flow and stick to non oxidized surfaces easily and keep oxygen away from surfaces that are already in good contact. If the leads are tinned before they are joined, then it is likely that the base metals of the parts will not make direct contact. This may or may not matter a tinker's dam, but some audio gurus could probably write many paragraphs about the potentially horrendous effects.

Seems to me that 4% silver in the presence of tin and lead might make a sizable difference in conductivity. With the copper clad aluminum wire often used in voice coils, the copper is only about 10% of the total cross section yet the conductivity zooms up close to that of pure copper wire.

http://www.randomhouse.com/wotd/index.pperl?date=20000114

moldyoldy
11-01-2006, 04:26 AM
A soldered braid crimp is fine unless the wire is subject to vibration. Inevitably, the solder wicks up the wire beyond the end of the crimp, rendering that portion inflexible. Vibration of the remaining stranded wire will soon break the wire at the point it becomes rigid.

Consider this; The element in your electric oven draws about 2,000 watts at temperatures up to 500 degrees. Not only is it connected with unsoldered crimp-ons, all the other connections in the oven are too. Most of these connections are push-on spade lugs too. If ANY of those connections presented a signifigant resistance given the relatively high currents, THEY would become an element so to speak, and quickly burn up.

Tinned stranded wire resists oxidation, remains flexible, and solders easily. Soldering the end of braided wire solid is not the same thing. Whether you're a crimper, a solderer, or a hybrid, treat yourself to a roll or two of tinned wire and you'll never go back.

Thom
11-01-2006, 11:23 AM
Can't argue with most of that. When looking for the conductivity of these alloys (which probably doesn't matter) one must look up each alloy. The individual percentages won't tell, any more than it will tell there melting points. The solder wicking will contribute to fatigue breakage in high vibration, but so will just crimping. Normally when stranded wire is (someone mentioned braided but the uses for that are much fewer) flexed the individual strands slide past each other in the flex area as each strand is traveling or defining or whatever, a different radius. Some are running different distances than others, so just crimping causes wire to be more likely to break from fatigue (I think this thread may break from fatigue, not sure if we crimped it or not) if it flexes. If you are concerned about that you need some sort of flexible strain relief to cause the flexing to take place over a greater length and away from the connection. Also those crimps in your oven or on your hotplate are hi temp. If the connection dropped .5 volts and it was 10 amps that would be 5 watts. That amount of heat could be easily handled in that situation and the .5 v would never be missed. On the other hand if you were running 10 amps through an equal connection in different circumstances 5 wats might be a lot of heat to get rid of and if you only had 5 volts you might really miss the .5 v. This throws a lot of people when they compair 110- 220 stuff to low voltage stuff. All the rules are the same but a 10% voltage drop is perfectly acceptible in house wiring. In audio maybe yes maybe no pick your authority

moldyoldy
11-01-2006, 01:50 PM
".....(I think this thread may break from fatigue, not sure if we crimped it or not)"...........

I'll second that Thom, those of us with dislexia and extra appendages from breathing lead fumes for decades aren't about to change our personal habits, and the rest are convinced we huff fumes for kicks, and left for ebay.

Maybe by the time I finish off the 4-5 lbs of Kester 44 I've got left they'll have a better solution. After all, if everyone's connections were perfect, what would those of us that fix stuff do for beer money when the SS dries up?

Ducatista47
11-01-2006, 07:34 PM
Before this is an officially dead thread, I want to say how much I appreciate all the knowledge given here. I learned a lot! This thread is a wonderful example of how nice it is to belong to LH, and to hang out here.

Unfortunately, it is also an example of semi off topic. Precious little was found about the original question so far. At least Thom was able to generalize about water and copper conductors.

I freely admit "topic creep" (think mission creep) is one of my favorite elements of the forums. I'm not complaining. :)

Clark in Peoria

doyall
11-02-2006, 07:18 AM
Unfortunately, it is also an example of semi off topic. Precious little was found about the original question so far.

To the contrary, I think that the direction the thread went was tremendously valuable in addressing the underlying premis of my question. The responses are most appreciated.

Ducatista47
11-02-2006, 07:32 AM
Doyall, mark that up to my apparently substandard brain functions. I forgot about the tinning wire part of your question. So I too wonder, can this product be used for tinning wire?

Clark

Thom
11-02-2006, 03:40 PM
Find out if it has any ingredients that are active to copper, or whatever material your wire is made of. If not you can try it, I would think.

audition
11-02-2006, 03:46 PM
As I was taught, the benefits of stranded wire go well beyond flexability, stranded wire can carry more current then that of a solid wire of the same diameter- why- because electrons flow only "around" the wire... not through it. Solid wire only has so much surface area, where stranded wire has alot more surface area for the electrons to flow- also I was taught after stripping stranded wire never to twist it if you are to use it in a compression connection or you will reduce the amount of strands touching at the "outer" surface of the bundle of strands within the compression connector- as well as you reduce the surface to surface connection of the strands "inside" of the bundle... if you reduce the amount of contact within the bundle of wires you reduce the overall amount of current the bundle will carry. Connectors are only as reliable as the outer metal on the connector - gold will not oxidize.....silver will.... etc. on down the line

Rudy Kleimann
11-04-2006, 01:38 PM
This throws a lot of people when they compair 110- 220 stuff to low voltage stuff

True, Thom. This is where high-quality, clean, tight connections are of paramount importance. Compression connections with clean wire and connectors, especially with low voltage such as audio signals at line or even more, mic level or high-current as in amp to loudspeaker wiring. Whether you use crimp-type compression fittings and follow-up with solder or screw-tight compression connections, no oxidation crossing the electrical path is the key. Oxidized metal acts as an insulator of sorts, reeking havoc at low voltages. Sealing a good, tight, gas-free joint with solder is a good idea if you don't need to take the joint apart again. Grease or liquid neoprene rubber dip (available in colors in small 3-4 oz. applicator-brush cans at The Home Depot) is good to put over screws and the like, since they are removable without much fuss.

In the electrical trades, there is a conductive grease (NoAlOx is one brand name) used to curb oxidation between the dissimilar metals of the wire and terminal (lug) and achieve a gas-free connection, as well as protect the joint from oxidation creeping in from the bared wire below the lug. For small wire, you rub it onto/through the strands before inserting into a terminal. For BIG wire, most large crimp-on lugs are pre-filled with this in the wire socket, which is only open on one end. When you shove the bare wire into it, the grease is forced into and around the wire. When the crimping tool (a high-pressure hydralic ram-driven crimper with matching dies for the lug) is applied, the excess will squeeze out around the wire. You're done.

Tin is an excellent metal for plating conductive surfaces due to its' very slow oxidation rate. Gold or Rhodium is best for this, but expensive. Gold wears off pretty easily too, since it is so soft. Tin is considerably harder than gold, so it lasts on connectors that are connected and disconnected a lot. Tin is commonly used on copper buss bars in electrical equipment, as well as terminals. Remember tin cans?;) 50 years from now, those buss bars will still be shiny, with no oxidation between them where they bolt together, along with no resistance causing voltage drop or heat build-up.

About the only place I think silver is used as a surface coating is on switch and relay contacts, where the contacts have a small contact area.

Someone else here expressed concerns about Marine-type or automotive-type crimp-on terminals being aluminum. I highly doubt it. Electricity and water will quickly corrode aluminum. Salt water would eat it away in no time. It's usually tin-plated copper, although some are brass. If in doubt, cut, file, sand, or grind one. You will see copper inside, even though diagonal-cutters will pinch the the tin coating over the cut most of the way. Considering how short the electrical path through the terminal is, it doesn't matter what it's made of, as long as the surface is clean.


...a 10% voltage drop is perfectly acceptible in house wiring.

Not true. The National Electric Code (NEC, Produced by the National Fire Protection Agency) limits this to 5% maximum. A voltage-drop calculation factors in the current requirements of the driven load, the length of the wire run supplying power, the conductivity of the metal used for the wire, and the wires' cross-sectional area (in AWG or circular mils). More than 5% voltage drop under load requires upsizing the wire.

Silver is the best conductor for wire, but is expensive, too soft for connections, breaks if pulled very hard, and oxidizes quickly. It has a conductivity rating of 106%, relative to copper at 100% and somewhere around 65% for gold and 59% for aluminum. Everybody thinks gold is the best conductor, but it isn't -not by a long shot. It's an excellent coating, as it takes forever to oxidize and become a poorly conducting contact surface (insulator). Try this question on your beer drinkin' buddies. Almost certainly, they'll all owe you a beer.

Bottom line
For all practical purposes, copper makes the best wire, and tin the best protector of connections. Anything better (Silver and Gold) is just too damn expensive for too little improvement and a lot more care in handling.

Ducatista47
11-04-2006, 06:13 PM
I use a high purity (or oxygen "free") copper lugs. My hi-fi shop has a variety of sizes loose in a plastic tray organizer, I'll have to ask what brand. It makes sense to me to use lugs as good as the wire you connect them to, so that might inform your decision.


You know, this has become a pretty useful thread. It could go to a technical reference secton.

An update. I did my homework as promised, and the lugs I use are Audio Magic brand, gold plated copper. I can't find these on their website. Perhaps only dealers can get them.

I saw an even better device in the tray, a large lug with a hole on the flat spade instead of a notch. The contact areas in the crimp tube and especially on the spade are huge. Also gold plated copper. Also expensive. Not Audio Magic.

Clark

Thom
11-04-2006, 07:05 PM
The skin effect refered to earlier is a high frequency phenamena. When really worried about it litz wire, which has each strand insulatedcan be had. The really big advantage to silver in contacts is that silver oxide is a very good conductor. actually there is a second advantage in some circumstances and that is that it is nearly impossible for silver contacts to weld together. I guess which is a better conductor would depend on how you measure it. By wire gage copper is quite a better conductor than aluminum. By weight it's the other way around.

Rudy Kleimann
11-04-2006, 07:13 PM
Excellent post, Thom. I knew there were other advantages to Silver plated contacts in switches and relays, but didn't know off the top of my head. I wonder why silver isn't used on RCA connectors, binding posts, etc? Could it be... shiny Gold looks better than oxidized (tarnished) Silver? Actually, I think Gold is better because it takes practically forever to begin to tarnish.

Copper would never be practical for long, high-voltage electrical power lines, due to weight and cost. Support poles and towers would have to be much closer together or copper would stretch to the point of breaking.

Thom
11-04-2006, 08:19 PM
I think most transmission line is made of either hardened copper or hardened aluminum and the aluminum is now much more common due to weight and cost and I believe even cooling, the aluminum is larger in diameter and has more surface to give off heat. A disadvantage to aluminum is it's rate of expansion it grows much more with heat so it gets longer and that has to be compensated for and connections both because aluminum oxide is an insulator, which can be handled as mentioned earlier and because it expands differently than copper connecting to copper is a bit trickey. Lots of other lines that are strung have a steel cable in them called a messenger, something to know about if you have a nice pair of cable cutters not designed to cut steel. It can hurt as much as the first scratch on a brand new car.

JBLnsince1959
11-06-2006, 05:45 PM
I think most transmission line is made of either hardened copper or hardened aluminum and the aluminum is now much more common due to weight and cost and I believe even cooling, the aluminum is larger in diameter and has more surface to give off heat. .

They use a composite of copper and steel. If you ever get a chance to be around electrial transmission wires you will see that a magnet will stick to the wires.

moldyoldy
11-10-2006, 04:52 AM
This thread has rambled, yet raised many valid points as well as a few yet-unanswered questions. It also made me realize that even though soldering is like second nature to me, I hadn’t done anything to advance my knowledge of the science of the art since…..let’s just say it was SNLs first season and leave it at that….So, I spent some time sifting the bits, snagging enough objective data for a refresher for myself, as well a decent foundation for a beginner. The following material is copied text compiled from several non-retail, industry sources, so there’s no smoke or mirrors. I focused only on data applicable to electronics, so we’re not talking oven elements or 7KV lines (no one mentioned underground transmission lines yet) Oh yeah, the answer to one of the original questions is in there too.:


"Soldering filler materials are available in many different alloys for differing applications. Traditionally, the eutectic alloy of 63% tin and 37% lead (or 60/40, which is almost identical in performance to the eutectic) has been the alloy of choice for most copper-joining applications. A eutectic formulation has several advantages for soldering; chief among these is the coincidence of the liquidus and solidus temperatures, i.e. the absence of a plastic phase. This allows for quicker wetting out as the solder heats up, and quicker setup as the solder cools. A non-eutectic formulation must remain still as the temperature drops through the liquidus and solidus temperatures. Any differential movement during the plastic phase may result in cracks, giving an unreliable joint. Additionally, a eutectic formulation has the lowest possible melting point, which minimizes stress on components during the soldering process.For environmental reasons, 'no-lead' solders are becoming more widely used. Unfortunately most 'no-lead' solders are not eutectic formulations, making it more difficult to create reliable joints with them.

Though the base material is not melted in a soldering process, some of the base material's atoms do dissolve into the liquid solder. This dissolution process enhances the soldered joint's mechanical and electrical characteristics. Lead and tin form a simple eutectic system with a small solid solubility of lead in tin and a rather larger solubility of tin in lead. In consequence, a solder surface may display reactions of either metal with some tendency, not always quite sharp, for the properties of the metal present in the higher proportion to predominate. Both metals are attacked by acids and alkalis but the presence of lead, which forms many more insoluble compounds than does tin, creates further possibilities for the formation of protective layers in near-neutral aqueous media.

The Tin/Lead Process

The tin/lead process is what is currently being done for the majority of electronic assembly in the US and throughout North America and Europe. What happens when lead-free components are put in place in assembly of this current technology?
Fortunately for assemblers the news here is good. Studies indicate that there are no reliability or processing issues when lead-free plating and finishes are used on components. In fact, lead-free components finishes have been used in electronic assembly for many years. The addition of extra tin does not raise the reflow temperature of the alloy. While more tin may dilute the amount of tin/lead intermetallics present, the tin/lead intermetallics do not go away and so the reflow temperature of the resulting alloy does not change.

The Lead-free Process

When assemblers move to lead-free connection materials the same question arises concerning using components with tin-lead finishes. The news here isn’t so good. The addition of small amounts of lead to lead-free connections can have a dramatic affect on the alloy integrity. When lead is added to a lead-free system the lead reacts with the tin forming the same low temperature intermetallics that are present in tin/lead systems. Even small amounts of tin/lead intermetallics will lower the reflow temperature of the alloy. The solder alloy temperature is usually described in terms of liquidus and solidus. Liquidus is the temperature at which the alloy changes from a plastic state to a liquid. Solidus is the temperature at which the material changes from a plastic state to a solid. The addition of lead does not affect the liquidus but it does change the solidus of the resulting alloy. An example of how much the reflow temperature can be affected by the addition of as little as 1% lead is shown below:

1% lead will drop the solidus by 40-50C. SnCu0.7; 227C to 183C
SnAg3.0Cu0.5; 220C to 179C
SnAg3.5; 221C to 179C
SnBi57; 138C to 96C

When mixing tin/lead and lead-free technologies it is important to note which technology you are trying to achieve. For a tin/lead technology adding lead-free components will not change the reflow temperature. For lead-free technology adding leaded components will lower the reflow temperature.

TIN

Tin (Sn) is a member of Group IV of the Periodic Table, along with carbon, silicon, germanium and lead. As a metal, the most important properties of tin are its low melting point, its non-toxicity, its resistance to corrosion, its' attractive appearance and the ability to readily form alloys with most metals to create useful materials.

Property
Atomic mass 118.69

Atomic number 50
Melting point 232C
Boiling point 2625C
Density 7.28g/cm3
Electrical resistivity at 20C 12.6 μΩ cm
Young’s Modulus at 20C 49.9GPa

SILVER

Silver is a very ductile and malleable (slightly harder than gold) univalent coinage metal with a brilliant white metallic luster that can take a high degree of polish. It has the highest electrical conductivity of all metals, even higher than copper, but its greater cost and tarnishability has prevented it from being widely used in place of copper for electrical purposes.

Phase solid
Physical properties
Density (near r.t.) 10.49 gcm−3
Liquid density at m.p. 9.320 gcm−3
Melting point 1234.93 K (961.78 C, 1763.2 F)
Boiling point 2435 K (2162 C, 3924 F)
Heat of fusion 11.28 kJmol−1 Heat of vaporization 258 kJmol−1
Heat capacity (25 C) 25.350 Jmol−1K−1


Applications


Q; Sn60 vs. Sn63; When is the use of one of these two alloys more appropriate than the other?


The Sn60Pb40 has a plastic range and puts down a slightly thicker coating of solder. Sn60 is often preferred for lead tinning and other solder coating applications. Sn63Pb37 is eutectic and as such has no plastic range. Generally it flows better than the Sn60 and is the preferred alloy for wave soldering and surface mount applications.


Q We are soldering to gold and we heard that we need a silver solder. Is this true?


This is a common misconception. You need a small amount of silver in your solder only if you are soldering to silver or silver plated components/leads. The small percent of silver in the solder prevents the silver on the leads from migrating into the solder resulting in a weak or brittle solder connection. The two most common situations are silver plating on component leads and silver palladium substrates. In both these cases the Sn62 alloy should be used. The high melting point of silver should also be considered when soldering temperature-sensitive electronic components.


When soldering to a gold plated surface the thickness of the gold is important. If the gold is thicker than 40-50 micro-inches, the solder most likely may not dissolve all the gold and bond to it. The solder will be dull looking and, if the gold content in the solder exceeds about 5%, the solder joint will be brittle. If the gold is thin, less than 20 micro-inches, it easily dissolves into the solder, making the solder joint look grainy. If the metal that was under the gold is not oxidized, the gold-contaminated solder will bond to it. However, as gold plates usually in a columnar structure, the gold should be at least 10 micro-inches thick to protect the base metal (in most cases nickel) from oxidation.


Q; What Does No Clean flux Mean?


Many fluxes fall into this category because the flux residues are not harmful to assemblies. It does not mean there will be no residues. All fluxes leave residues (the solids are the active portion of the flux that does all the work). Some flux residues are conductive or corrosive and must be removed. Other fluxes like the no-clean fluxes leave residues that do not need to be removed."

Ian Mackenzie
11-10-2006, 02:44 PM
That was an interesting post.

The lead free thing is also interesting. In many applications the pcbs holes are now plated through (tin) and aften surface mount technologies.

Nothing beats of course knowing how to make a good solder joint.

http://www.passdiy.com/howto/soldering.htm

I notice there is also Quad - Eutectic solder available now.

http://www.soniccraft.com/products/connections/solder/cardas.htm