Solder Types and Uses

FrankB wrote:

You can use alcohol , in limited amounts, indoors, but Acetone will harm you without proper ventilation much quicker.

That is why I normally have only one use for acetone, and use it only with a lot of ventilation - I use it to remove the soot from the inside walls of a transmitter cavity where a component has burned and deposited a lot of soot. I know of nothing else which removes soot from an unpolished aluminum surface as well.

I have had acetone discolor or dissolve some plastics in electronics. NEVER use it around plastic meter faces!

 (If you mix it with stryrofoam, (as will gasoline) it will dissolve the styrofoam to the point you can make castings with, but takes a long time to set.)

Acetone also causes kidney failure. I met one SFX tech who had his kidneys failing from Acetone exposure, and many of his co-workers were or had died from it.

You can use alcohol , in limited amounts, indoors, but Acetone will harm you without proper ventilation much quicker.

I used to use Freon TF as my go to cleaner, but the EPA banned it, like they did to so many actually effective products.  (It would also knock a mad hornet coming at you dead in half a heart beat).

Cliff Jones wrote:

A number of web pages say that lacquer thinner will eat plastics.

That is true, but almost any solvent used as a flux remover has the capability to damage some electronic components (even if only removing the printing from some capacitors). That is a major reason why I recommend 91% isopropyl alcohol to those new to electronic service - it is not as strong at removing flux as some chemicals but is less likely to cause damage. In my youth I was a chemistry major in college, and I likely understand more about the chemical properties of flux solvents than most restorers. I know when to use powerful solvents such as lacquer thinner and acetone (which is also in my shop) and when to use a less powerful chemical.

A number of web pages say that lacquer thinner will eat plastics.
Go online and look at a MSDS for its chemical makeup, it has toluene and a lot of other not so friendly to plastics chemical makeup.
So I would avoid it myself, but there are better web pages to search about cleaning circuit cards.

At tektronix we used Freon baths, but that is now band. The military requires the use Of Isopropyl alcohol, at least when I was working.

Take a look at this link. A lot of good info.

[You must be registered and logged in to see this link.]

FrankB wrote:

The best flux remover I have found is denatured alcohol.

I carry a commercial flux spray can for work, but in the shop I normally use lacquer thinner when I am sure it won't attack anything such as solder resist. If I decide I need something milder I use 91% isopropyl alcohol.

Many compounds contain ingredients which should be avoided. "Rubbing alcohol" can indeed contain other ingredients which should be avoided, but its active ingredient is isopropyl alcohol and 91% isopropyl alcohol is readily available, so I suggest using that. In any case one needs to use only enough solvent to do the job, and I apply it with cotton tipped swabs.

There are many types of solder for varied uses.

I will mainly cover typical common types you will run into, and not the exotic types, based on my experience. You will find solder sold in many different gauges, like wire is. The smaller the gauge, is generally the best for PC boards, while the larger gauges are better for old radio work, as you will use up a lot of fine solder making a connection to the heavier parts in a point to point radio or TV set. I typically use 20 or 22 gauge rosin core myself for PC work and the 18-16 gauge for the old radios & TV sets. It is a matter of your preference.

Of note: Using the PROPER temperature soldering iron/gun is CRITICAL. Too low an iron temperature means you have to stay on the connection much longer, often damaging the part or lifting the traces.  My experience is an 800 degree F tip lets me get on and off quickly, while making a good repair. A good joint should be shiny, not dull. "Lead Free" always seems to make dull joints though.
 Be sure the tip of your gun or iron is properly tinned and clean.

The most common is lead/tin solder. It comes with flux core in it and the most common types used are 60/40 and 63/37. IMO, 63/37 is superior to the 60/40 mix. (40 % Lead and 60% Tin).

The "Newest and greatest" per the EPA is "Lead free solder. My experience is it leads to a vast number of "ring cracks" around parts and has minimal structural integrity compared to the regular types above.  High failure on soldered connections compared to lead/tin types of solder. (My personal opinion is its pure garbage based on many years of having to repair broken connections made with it). Look up how much RCA lost on warranty work and lost repeat sales from using the "Lead Free" solder on the CTC 176, 177, 178 and 179 chassis. They were a cash cow for the repair industry due to all the bad solder connections and damaged parts caused by the bad connections. 

Next is Silver Solder. Great stuff. Harder than the lead based solders, but much more durable. Drawbacks are it costs more and requires a higher temperature to melt. Used in the space program, per one tech who used to work on electronics for it.  Also fantastic for jewelry and eye glasses..

Acid core solder: DEATH ON ANY ELECTRONICS- Great for sheet metal and brass radiators. The acid core just eats up the copper traces  and components and is a nightmare to completely remove from equipment that a DIY used it on.

Bar Solder & Solid Solder:  Great for plumbing and soldering sheet metal when used with the proper flux. I have used it to solder up some chassis I made, but really requires a blow torch. 

(Gold Solder is used for specific types of jewelry and eyeglasses. I never have used it myself, but oh my! it really fixed my broken glasses. I have never found it in consumer electronics. I mention it here because you can buy it from various sources, and it might turn up at a garage sale).


Flux- Used to allow the solder to flow. Rosin liquid is my favorite, but NoKorode (Or as we call it "Noke") is OK for electronics. Be sure what ever flux you get is suitable for the solder you are using, and not an Acid Base flux or Soldering Acid liquid flux. There are several brands out there that are fine. One thing I found is" NoKorode" brand flux seems to work fine even after 80+ years sitting in the original can!  My preference is liquid rosin flux, but for heavy duty soldering or "dirty" metal. good old "Noke" seems to be unbeatable. 

On old solder, the flux sometimes fails to work like it should. I often buy garage sale & Ham Fair lots of solder and some is 60+ years old and solder doesn't properly flow so adding "external flux" can make it work properly again. Often people toss all the solder in a box at the sales, so look before you use solder. My most recent box had 10 lbs. of Word is Censored rolls and coils of solders in it and a Weller 2 heat gun.
 Most rolls were marked but odds & ends I put in the recycle pile if I could not ID them. There were rolls of flux core, acid core, solid core, bar solder and silver solder too!

Using an old soldering tip and a bit of experience you can ID most of the solder types. Acid core smells acrid and sharp. Rosin smells like, well rosin. plumbing, solid solder will melt very slowly and not flow well without flux. Silver solder will require more heat to melt and look very shiny.

The best flux remover I have found is denatured alcohol. Rubbing alcohol, per a chemistry major who became an MD told me it leaves a bit of oil on what you clean with it, so it is not good to use. (We were commercially building computer boards at the time and I caught heck for using rubbing alcohol!). Some special solders have a water soluble flux in them also.