I agree with the others and suggest a lead based solder like this one:
.020" dia. Sn63/Pb37 Water Soluble Wire Solder (1 lb. Spool). You won't have any issues with the tin whiskers or with the joint cracking later.
I do know lead based solder is illegal in different areas around the globe though so you may want to check it out.
.020" dia. Sn63/Pb37 Water Soluble Wire Solder (1 lb. Spool). You won't have any issues with the tin whiskers or with the joint cracking later.
I do know lead based solder is illegal in different areas around the globe though so you may want to check it out.
Lead solder is primarily intended for electronics. Anyone who has used lead free solder for electronic works knows that it is crap. You would not use lead for anything that would be in constant contact with people/animals or food & drink for said creatures. Lead in metallic form is not very bio-absorbable. That being said, I always wash my hands after working with 60/40 solder and I would not wear a lead bracelet. 
"OOOoooooo lead! Toxic!" is what you hear from the uninformed. These are the folks who believe shooting lead bullets into the ground will contaminate the water table.
When metallic lead is exposed to the elements it forms a layer of lead oxide on the surface making a barrier so the lead inside of the bullet doesn't leach out, sort of like a cyst inside of your body. American Civil War bullets are pulled out of the ground all the time, completely intacked. It takes a PH other than 7 to dissolve exposed lead into the water. Unfortunately water systems do not distribute distilled water. Also this is a good reason to not throw old electronics into the landfill, where biological de-composition can acidify the soil dissolving the lead alloys. To believe until recently they actually put tetraethyl lead in gasoline!
Frankly there are much worse common things out there than lead solder. One that comes to mind is all those Mercury vapor 'energy saver' damn flickering light bulbs, manufactured in China because most countries have high restrictions on manufacturing Hg products. This is all a hoax to corner a market. If you want to really save energy, turn down the thermostat in your home a few degrees in winter and up a few degrees in summer. Leave my incandescence light bulbs alone or I will start using oil lamps again! BTW, oil lamps with a proper lamp shade do produce quite pleasing light.
"OOOoooooo lead! Toxic!" is what you hear from the uninformed. These are the folks who believe shooting lead bullets into the ground will contaminate the water table. When metallic lead is exposed to the elements it forms a layer of lead oxide on the surface making a barrier so the lead inside of the bullet doesn't leach out, sort of like a cyst inside of your body. American Civil War bullets are pulled out of the ground all the time, completely intacked. It takes a PH other than 7 to dissolve exposed lead into the water. Unfortunately water systems do not distribute distilled water. Also this is a good reason to not throw old electronics into the landfill, where biological de-composition can acidify the soil dissolving the lead alloys. To believe until recently they actually put tetraethyl lead in gasoline!Frankly there are much worse common things out there than lead solder. One that comes to mind is all those Mercury vapor 'energy saver' damn flickering light bulbs, manufactured in China because most countries have high restrictions on manufacturing Hg products. This is all a hoax to corner a market. If you want to really save energy, turn down the thermostat in your home a few degrees in winter and up a few degrees in summer. Leave my incandescence light bulbs alone or I will start using oil lamps again! BTW, oil lamps with a proper lamp shade do produce quite pleasing light.
Actually, it's not that bad. For a while, I was one of the world's largest consumers of tin/silver solder, which I used exclusively for electronics. CERN took that mantle over during the LHC build.
It takes a little bit more knowledge, a good understanding of flux, and a good understanding of visual inspection criteria for non eutectic joints.
To me, there are two primary issues. First, most of the components are manufactured with pure tin plating, either as plated, or fused. If you don't consume that pure tin with either tin/lead or tin/silver, you setup for whiskers.
Second, the higher temp requires a bit more understanding in how to heat the joints correctly. Tin/silver temperatures are less forgiving of a marginal process.
But I certainly agree with you on the mercury CFL's..
jn
Yeah, takes a lot of flux or you get a grainy suface tension and poor flow.
The extra heat can damage small IC's and the pin connections inside the package. It is harder to focus the extra heat in a small area to repair SMD parts. You are less likely to damage the PCB with leaded solder and a smaller, cooler iron.
Poor flow, definitely agree. Surface tension can be affected as well.Yeah, takes a lot of flux or you get a grainy suface tension and poor flow.
Grainy surface can be a result of several things. Copper dissolves into the melt, and the copper tin crystals freeze out 2 degrees above the eutectic, so as the freeze occurs, the crystals form first, giving a grainy texture. Gold will also do this if the plating is too thick. As an added bonus, the gold can make the joint brittle.
For most encapsulated components, the wirebonds aren't really at risk. If the package has gold wires on aluminum, overheating could start purple plague. But most commercial uses aluminum wires.
The bulk of the overheat problems are popcorn and pullback on the leads. The encapsulation may be pushed past the transition temperature, and when it goes soft it expands at a faster rate. This pushed the plastic into compression at the leads, deforms it, and during cooldown it can retract from the lead metal. Flux will most certainly wick into it there, and depending on the packaging design, may allow the flux to attack the wirebonds or even the chip itself.
Definitely agree there. Many are impatient, so turn up tip temp too far. It causes a very narrow window for the actual work before the work temp climbs too high. For me, components which I cannot see with the naked eye also cause problems. Unfortunately, that category is consistently becoming larger..
Absolutely agree with you on that..
jn
Quick question here:
We can use whatever solder we want for home-built stuff, but what about mending a commercially made piece of equipment?
How do you tell what sort of solder was originally used, and how bad is it if you guess wrong, and end up mixing e.g. leaded and lead-free solder?
This isn't limited to audio equipment, could be anything from a lamp dimmer to an ATX power supply.
We can use whatever solder we want for home-built stuff, but what about mending a commercially made piece of equipment?
How do you tell what sort of solder was originally used, and how bad is it if you guess wrong, and end up mixing e.g. leaded and lead-free solder?
This isn't limited to audio equipment, could be anything from a lamp dimmer to an ATX power supply.
Technically, yes. Legally, I assume so.
Tin/lead solder will have a shiny appearance. The normal criteria for a good tin/lead solder joint included look for shiny. No shiny.... bad joint.
All other solders, you generally see a frosty look to the joint. To really inspect, you have to look for the meniscus where the solder meets the leads or pads, or even small cracking indicative of a cold solder joint.
There really is no problem with mixing lead and lead free I'm aware of. The combo will have an additional eutectic at 179C due to the silver, but that shouldn't be an issue.
jn
There can be, we have to have all our BGA's re-balled with balls containing lead (lead in your pencil
). Problem is different temps, tin/lead will reflow before the Pb free, can lead to bad joints as the intermetalics don't always form properly. Again for home use lots of flux helps.Commercial equipment made after 2006 will be lead free, as that was the deadline, though many firms used it well before that date, it was a good marketing point, how green they were (even though the carbon footprint goes up due to elevated temperatures).
Pencil lead is carbon on this side of the pond. As well as some kind of polymer.There can be, we have to have all our BGA's re-balled with balls containing lead (lead in your pencil
You'll have to explain how intermetallics don't form properly, I believe you are perhaps mixing melt/eutectic temps with the formation of intermetallics. I posted a phase diagram earlier, but it doesn't have the trinary nor it's eutectic on the chart, but it is close to tin/lead in percentage but 4 degrees lower.
If you have replaced BGA balls with tin/lead, I assume you've done so with other components? Or are you trying to mix tin/lead BGA soldering with external component lead free through the same wave or IR?
I've not seen nor heard of normal board processing consuming all the tin in the mix by the copper to create both copper/tin intermetallics to the exclusion of all tin/lead.
Yah, the decision made no technical sense, just political.
jn
Um, I speak from experience.
The hardest part is getting a flux which activates below 150C and remains unburned above 260 C.
I've production line experience with darn near every solder alloy known to man. Didn't like most of em, but still did it. Lead indium at 125C up to 95/5 lead/tin (at 325 IIRC), gold silicon, gold germanium..
Hydrogen belt furnace, nitrogen belt, dap, focussed IR, hot air, vapor phase reflow, resistance heating, induction heating, a little wave and belt IR, heck....even a soldering iron.
So as I stated, I am unaware of any issues surrounding the mix. And again state that it's always a flux issue.
jn
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