Hi.
There is few recognized brands that behave as we want. Which is your preferred :
- Brand ?
- Alloy 60/40 ; 63/37 ; other ?
- No core / single core /multicore ?
- Rosin / acid ?
- Do you use lead free / silver for hobby ?

When I was like 12, buying solder was not painful at all to my wimpy wallet. Now it is and my wallet is not wimpy. Abuse in price makes us try other brands, to find sheeet. We are forced to pay more for batteries with lead, and we pay again to recycle. And lead is supposed to have very little demand now that international regulations do not want it.
Someone is a lot richer from the price strategy. Ordering via mail makes it worse. The postal office champions of incompetence losing billions and increasing fees twice a year make everything more expensive.

 

Kester 44 63Sn/37Pb rosin core 610°F/320°C
Two sizes 0.015"/0.38mm for SMT and 0.031"/0.79mm for thru-hole.

https://www.raypcb.com/60_40-vs-63_37-solder/

Old Tektronix tube oscilloscopes came with a supply of silver solder inside each scope.
This is used when doing repairs on the ceramic strips. I have kept some of this for when silver solder is required.

 

These days, I use Alphametals Cleanline 7000 63Sn37Pb noclean, either 0.032" or 0.015" though I have a couple other diameters and half a dozen partial rolls of Kester.

I have a small roll of lead-free solder in case I ever need it. I bought some low temp paste from AliExpress just to have it on hand.

Solder prices are outrageously high these days. I bought a couple dozen 1 pound rolls of the Alphametals solder about 10 years ago from a company that sold surplus stock/liquidations that they bought by the pound on eBay. They offered local pickup and were close enough that I saved a lot on shipping. I stopped buying from them when they stopped offering local pickup.

 

Hi,

I use 63/37 because it melts at a lower temperature so makes soldering faster and it seems to flow better than 60/40.
I also use 'solder paste' which is amazing stuff. Not sure of the lead/tin ratio but it flows like water and 'finds' the pins by itself due to surface tension. It's amazing stuff. Probably the only way to solder very small multiple pin IC packages. Heat gun required normally.

 

Along with the Kester 44 eutectic solder I also use a dab of their liquid no-clean Kester 951 flux. Works great especially with older somewhat oxidized parts and only leaves a bit of white dust residue that can be removed with water if desired. It is much easier to clean up than rosin-based liquid or paste fluxes.

 

These days nobody should ever use acid flux for anything electronic.
Solder with rosin flux core 63/37 tin lead eutectic is the best for prototype, repair and lab work, lead free is just harder to work with, I don't like it.

 

These days nobody should ever use acid flux for anything electronic.
Solder with rosin flux core 63/37 tin lead eutectic is the best for prototype, repair and lab work, lead free is just harder to work with, I don't like it.

Hi,

Same here, I don't use lead free and probably never will unless I run out of the usual solder, which is very doubtful. I never use acid flux either. I do have some liquid rosin flux I use now and then for difficult solder jobs.

 

I begrudgingly changed to Lead Free when RoHS forced me to, and have kept with it. It's not so bad as it used to be. TSC with a decent flux is a just-about-OK solder to use. Its only favourable feature is that it is stiffer, so you can unspool a length from the reel and you don't need a "third hand".

I think it's more important to have a relationship with a supplier, who can advise on which solder to use, which flux, which solder paste and what temperature to set the iron.
I use these companies (which is no help to anyone at the other side of the world)
https://solderking.com/
https://www.warton-metals.co.uk/

Another few important points:

1. Use the right diameter solder. 1.3mm for big terminals and 0.8mm for boards. 1.3mm is cheaper - so keeping two reels in stock will save money in the long run.
2. If it needs more flux, put some flux on it, don't just add more solder and expect the flux core to do the job,
3. If you have to use lead-free don't use the very high tin content solders (99S and 99C) because they suffer from tin-pest.

 

The melting point of 63Sn/37Pb is 183°C/361°F.
The recommended soldering temperature is 315-343°C or 600-650°F.
My Weller WCPT soldering station tip is preset for 700°F.
I change to a 800°F tip when using lead-free solder.

 

The melting point of 63Sn/37Pb is 183°C/361°F.
The recommended soldering temperature is 315-343°C or 600-650°F.
My Weller WCPT soldering station tip is preset for 700°F.
I change to a 800°F tip when using lead-free solder.

I used to have a TCP, and I used to run it on 7 tips for leaded and 8 tips for lead-free, but I found it used to oxidise the tips badly with lead-free. I changed to a different Weller, and it doesn't seem to have the problem.

 

I currently use MG Chemicals 60/40
RA core Flux (no clean type)
The roll I'm looking at right now is 4896-227G

 

Hi.
There is few recognized brands that behave as we want. Which is your preferred :
- Brand ?
- Alloy 60/40 ; 63/37 ; other ?
- No core / single core /multicore ?
- Rosin / acid ?
- Do you use lead free / silver for hobby ?

When I was like 12, buying solder was not painful at all to my wimpy wallet. Now it is and my wallet is not wimpy. Abuse in price makes us try other brands, to find sheeet. We are forced to pay more for batteries with lead, and we pay again to recycle. And lead is supposed to have very little demand now that international regulations do not want it.
Someone is a lot richer from the price strategy. Ordering via mail makes it worse. The postal office champions of incompetence losing billions and increasing fees twice a year make everything more expensive.

Others have provided a lot of good information, here is my accumulated experience, for what it’s worth…

First, it is important to understand just what soldering is. One might think soldering is like “gluing with molten metal” but that’s not the case. Soldering connects the two metal things being soldered by alloying with their metals to created a shared layer of a third metal that bonds and electrically connects them.

This interface layer is the goal of soldering, and the robustness of it is the test of how good a solder joint is. Solder itself needs to meet this requirement and other practical ones. Like all things in engineering, this is an optimization problem that has to balance a variety of requirements including practical things like actually facilitating the soldering process, the time it takes, and the cost as well.

For hand soldering the alloy chosen has to make manually forming the solder joint as easy as practical. It also has to allow minimal heating of the components being soldered, and reduce the chances of spoiling the joint after it has been made. To this end, there are two alloys I use and recommend for general hand soldering.

First is 63Sn/37Pb alloy. This is a eutectic alloy and being so has two distinct advantages. Eutectic alloys have the lowest melting point for the metals involved. This can help reduce amount of heat that has to be transferred to the parts (leads, traces, etc.) being joined. This, in turn, reduces the temperature rise of the most vulnerable parts of the components, limiting actual or possible damage to them.

The second advantage of a eutectic alloy is that is has no plastic phase. When metals melt, the have three basic phases: liquid, plastic, and solid. The liquid is melted, and the solid is… solid. The plastic is a range of temperatures for non-eutectic alloys where it’s neither liquid nor completely solid, it is “pasty”, some solid, some liquid mixed. This is subject to plastic deformation.

Plastic deformation is when a stress is placed on a material that causes it do deform permanently. Unlike the liquid phase that just flows when stressed, and solid which is subject to plastic deformation but only under a very heavy stress, solder in the plastic phase is very easy to deform, and the result is a cold solder joint.

This is one of the most common defects in hand soldering, particularly for the neophyte. The inability for a 63Sn/37Pb alloy solder to make a cold joint is a big advantage, even for the experienced person. This makes 63Sn/37Pb my very first choice for hand soldering.

The second is 60Sn/40Pb alloy. If eutectic alloy is so wonderful, why choose some other? As I said, engineering is about optimization, and the optimal can only be tested against requirements. 60Sn/40Pb alloy can make cold joints, and it melts at a somewhat higher temperature—so when would I use it?

One of the characteristics of a solder alloy is wetting. That is, how readily does it form that interface layer. It turns out that 60Sn/40Pb alloy is considerably better at wetting than its eutectic counterpart. So, when tinning leads, wires, and PCB traces, where cold joints aren’t a concern, nor is heat likely to be a problem. 60Sn/40Pb alloy is the go-to for solder pots, for example.

Other alloys, such as lead-free and silver bearing solder also have optimal choices. Each formulation does have a eutectic alloy. For example, I have a spool of Chip Quik SMD3SW.020 62Sn/36Pb/2Ag alloy which is also a eutectic alloy. In fact it has a melting point about 4℃ lower than the 63Sn/37Pb alloy. There are some places where the silver is an advantage chemically, and it‘s a little mechanically stronger.

I do very little lead-free soldering, but I have a spool of Kester 257 in 96.5Sn/3Ag/.5Cu for cases where I need to. Both of these are no clean flux cored solder, with water soluble residue that doesn’t have to be removed but can be with volatile solvents.

On the subject of flux, it’s critical to use a good one. First, unless you have enough knowledge to do otherwise, buy flux cored solder for everything except solder pots. Even though I have only flux cored solder, I still have and use paste, sticky, and liquid fluxes for various things.

Today, very few people would have a reason to use any sort of corrosive flux on electronics. Even highly activated fluxes have little application with the availability of very effective no clean options. My go-to liquid flux is Kester 951 no clean. I have it both in bulk liquid and in a flux pen and I think everyone should have a flux pen. This is like a chisel point Sharpie that has the 951 instead of ink. It is the most convenient and efficient way to apply flux to pins, leads, pads, and traces.

I also use Chip Quick paste flux that comes in a puck shaped container making it excellent for dipping leads and stripped wires needing tinning. Once something is tinned, there is no need for flux. Flux is to deal with oxides. It removes oxides from the component leads and traces and so long as it is on the surface prevents re-oxidation. The joint is made under the flux protecting it from oxidation and promoting wetting.

But if you have tinned surfaces this is irrelevant. So, always tin leads and pads. The resulting joint will be much easier to make and much less likely to be electrically dodgy. Generally speaking, I would only buy solder from repeatable companies like Chip Quick, Kester, Multicore, and the like. This is not an exclusive list, but you can ask around about other brands. One clue is if the company has documentation on the solder like MSDS documents and datasheets.