Small leaded solder <0.25mm where to purchase?

[Jester]

When soldering really fine pitch components I find my smallest solder (0.3mm) is on the large side. Looking at Digi-Key anything smaller is not available in leaded form.

[rhb]

The smallest lead/tin solder I could find is 0.38 mm from Multicore.  Where did you find 0.30 mm?

[malagas_on_fire]

I've found some 0.3mm leaded solder on Ebay with 63% Sn and 37% Pb  :

http://www.ebay.co.uk/itm/Solid-Solder-0-3mm-Flux-Core-63-Tin-37-Lead-Long-Wire-Reel-Y5-/273033925901?roken=cUgayN

[calexanian]

Kester makes .01 in their line. I think that’s .245 mm or something like that. I have used the 44 type flux core for smt rework. They also have it in no clean, but I have that in .015 size

[Smokey]

Looks like you can only get the really small stuff in huge quantities. 
It would take me a thousand years of rework to use a 1lb spool of 0.010in solder!

[mikeselectricstuff]

The thin leaded I've had from Ebay has been universally crap.
 
0.3mm is about the smallest that's reasonably available - I've never felt the need for smaller - tend to use paste for tiny stuff

I have some Stannol 535235 0.3mm which is excellent. Sn60 Cu39 Cu1
 

[SiliconWizard]

I use a 96SC 0.23mm from Multicore (it's lead-free) and it works fairly well. I've found larger soldering wire (obviously for larger components) to be more annoying to deal with as lead-free than as leaded, but for the smaller jobs it's fine for hand soldering IME. And it's better for your health.

[mikeselectricstuff]

And it's better for your health.

Nastier fluxes in leadfree are a bigger immediate health issue than the metal.

[SiliconWizard]

And it's better for your health.

Nastier fluxes in leadfree are a bigger immediate health issue than the metal.

Maybe for some. This particular one has a rosin-based flux (refer to safety sheet) just as most of leaded solder wires, so I'm not sure there's a big difference here, except you're bound to use a slightly higher temperature? And using a fume extractor is always a good idea.

[nctnico]

When soldering really fine pitch components I find my smallest solder (0.3mm) is on the large side. Looking at Digi-Key anything smaller is not available in leaded form.

You are doing it the wrong way. Buy good flux and use a big tip. You'll see you can solder multiple pins in one go without making a short. The flux takes care of that.

[Smokey]

When soldering really fine pitch components I find my smallest solder (0.3mm) is on the large side. Looking at Digi-Key anything smaller is not available in leaded form.

You are doing it the wrong way. Buy good flux and use a big tip. You'll see you can solder multiple pins in one go without making a short. The flux takes care of that.

This is the sledge hammer approach.  It may work if you are in the middle of an empty warehouse, but I woulnd't be swinging that thing in the middle of the kitchen next to all the flatware.  Any sort of high density layout will end up knocking off parts with the flood and wipe method. 
Just go pin to pin with a good quality iron (Metcal!) and a good quality fine pitch solder with a good quality flux core under a good quality microscope. 

[rhb]

Get a drawplate from a jewelers supply and just draw the solder down.  This one will get you to 0.20 mm.  That's  smaller than the 1st string on my guitar. I doubt that tin-lead solder could be drawn finer except in very short pieces.

https://www.seattlefindings.com/Draw-Plate-Round-10-32-Gauge_p_4067.html

I *should* have thought to mention this long ago.

[Smokey]

Get a drawplate from a jewelers supply and just draw the solder down.  This one will get you to 0.20 mm.  That's  smaller than the 1st string on my guitar. I doubt that tin-lead solder could be drawn finer except in very short pieces.

https://www.seattlefindings.com/Draw-Plate-Round-10-32-Gauge_p_4067.html

I *should* have thought to mention this long ago.

The flux is in little channels in the core.  Not sure how well it will appreciate being drawn through a die.

[wraper]

TME
Although shipping to US may seem a bit expensive if you want to order only a small spool.

[rhb]

Get a drawplate from a jewelers supply and just draw the solder down.  This one will get you to 0.20 mm.  That's  smaller than the 1st string on my guitar. I doubt that tin-lead solder could be drawn finer except in very short pieces.

https://www.seattlefindings.com/Draw-Plate-Round-10-32-Gauge_p_4067.html

I *should* have thought to mention this long ago.

The flux is in little channels in the core.  Not sure how well it will appreciate being drawn through a die.

I take it you are not familiar with how flux core solder is made.  They do *not* make 0.3mm wire with holes in it and fill them with flux. They make big fat wires and then draw them to size.  This is how *all* wire is made whether flux cored or not.  And always has been since humans started making wire.

The round candies with the patterns in them are made the same way, except that they roll them as sugar doesn't have any tensile strength.  Same thing for the glass equivalent.

The real problem is a 0.2 mm lead/tin wire is about as stiff as a wet noodle.

[Smokey]

Get a drawplate from a jewelers supply and just draw the solder down.  This one will get you to 0.20 mm.  That's  smaller than the 1st string on my guitar. I doubt that tin-lead solder could be drawn finer except in very short pieces.

https://www.seattlefindings.com/Draw-Plate-Round-10-32-Gauge_p_4067.html

I *should* have thought to mention this long ago.

The flux is in little channels in the core.  Not sure how well it will appreciate being drawn through a die.

I take it you are not familiar with how flux core solder is made.  They do *not* make 0.3mm wire with holes in it and fill them with flux. They make big fat wires and then draw them to size.  This is how *all* wire is made whether flux cored or not.  And always has been since humans started making wire.

The round candies with the patterns in them are made the same way, except that they roll them as sugar doesn't have any tensile strength.  Same thing for the glass equivalent.

The real problem is a 0.2 mm lead/tin wire is about as stiff as a wet noodle.

You are correct.  I have no idea really. 
So here is a picture from Henkel of their Multicore cross section:

http://stores.acrosales.com/multicore-rosin-core-solder-sn60-pb40-063-wrap-3-370-flux-one-pound-spool-mm00994-idh-386832/

Two questions:
1) if they were to draw that down through a die, how do they keep the internal structure intact and not just get crushed?
2) When do they put the flux in?  At full diameter before being drawn, or at final dimensions?

[Rerouter]

The flux would be added early on, as volume is preserved.

The structure is maintained so long as you do not selectively work harder a side of the drawn material.

The same is done for copper clad aluminium wire, get a 3 inch piece of stock with the desired ratio and pattern and just draw to size,

There is both hot and cold drawing, but soft materials like this can be cold drawn without too much issues.

[rhb]

Those are likely to be the starting point for the draw.    There are two ways to make them.  By casting or by extrusion.  For volume production, extrusion would be more likely as it provides a more even grain structure.

It's  probably cut to a convenient length and then the flux forced through the holes by hydraulic pressure to ensure a complete fill.  An air bubble in the flux would cause the wire to break during the draw.  The drawing machine would have multiple carbide or diamond dies in series.  For certain metals, there would be an annealing furnace between the dies to counteract the work hardening of most metals.  Copper and silver are particularly prone to work hardening.

The final ratio of flux to metal would change depending upon the relative bulk moduli (incompressibilities) of the metal and flux.

I don't know how hypodermic tubing is made, but I'd guess that it is drawn with liquid sealed inside.  If tubing is being bent in complex shapes it is common to fill it with sand to prevent it collapsing.

At high school physics level, students are told that water and other liquids are incompressible, but that is only relative to gases.  I was involved at the research level with the relative compressibilities of porous media when I was working in the oil industry.  The changes in the bulk modulus of the fluids from oil to water to gas produce distinctive changes in the reflections.  Gas filled formations produce very large reflections relative to oil or water.  Just to keep things interesting,  the moduli vary with temperature and pressure and the reflection amplitude varies with angle of incidence.

I have a roll of 0.35 mm Multicore and find it is quite difficult to keep it from bending when I touch it to the joint.  Eventually I plan to make a dispenser that looks like a pen with a roller to feed the solder from a small spool.  The flint wheel from a disposable lighter for the feed roller, a piece of fine hypodermic tubing and an old ball point pen.  I shudder to think what 0.2 mm will be like, but I ordered draw plate along with half round and square plates and drawing tongs.

[Smokey]

Looks like you can only get the really small stuff in huge quantities. 
It would take me a thousand years of rework to use a 1lb spool of 0.010in solder!

Well being unable to find a smaller quantity of this stuff right now, I'm now the proud owner of a thousand years worth of 0.010in solder in a 1lb spool.