Solder 60/40 or 63/37

This is a topic that has been discussed for many times on Internet. Solder 60/40 and 63/37, no matter cost wise or property wise, these two types of solder are quite similar to each other. The solder 63/37 is eutectic solder alloy which has no pasty range, it's melting point is 183℃, while solder 60/40 still have a small pasty range at 183 to 190℃.

Let's see how the experienced solderer comment on this:

Comment 1: 

In my opinion and yours may be different. 63/37 has a very limited plastic range. I find it questionably better on a printed PCB were you want to get in and out in minimal time. Only then and only rarely I find it better than 60/40.
I like the 60/40 in all most every application. It flows better and becomes a solid during cooling more consistently . As I said it is just my opinion but I have 1 role of 63/37 on the back of the bench and several roles of 60/40 in reach. 
Joe

Comment 2:

 I think the eutectic is over-blown. I've used both for many years and have not noticed any difference.

Just don't get the lead-free junk.

TOM K8ERV Montrose Colo

Comment 3: 

Contrary to the others,

I would stick with the eutectic 63/37.

The idea behind the 63/37 is that it goes directly from liquid

to solid. The plastic state is virtually non-existant.

I use ONLY 63/37.

KB3LIX

Comment 4:

The 63 / 37 is the Eutectic (lowest melting point) for Tin / Lead alloy.

With the Tin?Lead eutectic there is NO plastic state/phase between solid and liquid. 

SO, cold solder joints are less likely for the begineer.

The 60/40 is standard formulation used for decades (strength versus melting temperature),

has a slightly shiny solid state -- when compared to 63/37 alloy. 

It does have a "Plastic state" range of about 10 degrees -- if joint is moved during this phase - a cold solder joint results.

There are advantages to some solder alloys (Tin, Lead, Silver, etc.) for higher melting temperatures, strengths, etc.

IF you are using QUALITY soldering stations (Weller EC, TECP, WS series; Hakko 936 or new 888) you will likely not see

many differences in usage. 

However, IF you are using bargain bin stick irons (NO temeprature control of tip) -- then soldering is very depedent on your skills and experience. 

This is where the novices and apprentices in electronics fail in the repair work that I have examined / reviewed.

The R/C hobby; audiophiles/guitar amplifier hobby were full of bad examples and techniques -- however the Internet is slowly educating those markets

and they are moving to crimp connectors to avoid the education / "learn skills" time.

w9gb