Usually my circuits are full of very fine-pitch SMD components. I solder the prototypes manually, which takes a lot of time. Good tools and high-quality solder can speed up the process.
I prefer using leaded solder, as it flows better at relatively low temperatures. This way I can prevent my components from overheating. Leaded solder is not allowed for commercial products, but is okay for prototyping.
There are several types of leaded solder wire on the market. I'm trying to find out which one is "best". Let's define "best" as follows:
Low melting temperature (prevents overheating components).
Good wetting of pads and pins.
Preferably contains some flux, so one doesn't have to apply it all the time externally.
Very fine diameter for soldering small components (like LFCSP package, 0402 or even 0201 resistors, ...)
Price is no issue.
I have several questions:
1. Tin - Lead alloys
I read on Wikipedia that the Sn60Pb40 solder is very popular for electronics (I agree, I have used this one so far). Wikipedia also mentions that Sn63Pb37 is slightly more expensive but also gives slightly better joints.
What do you think about Sn60Pb40 vs Sn63Pb37? What is actually the difference?
2. Exotic alloys
But these are not the only solder alloys. More exotic combinations - containing tin + lead + silver and even with gold exist.
Will these exotic combinations change the properties?
3. Bismuth and Indium alloys
Some of you made me aware of Bismuth- and Indium- based alloys. I've dedicated a new question to cover them: Bismuth or Indium solder - what would you choose?
NOTE: I use a solder-smoke extractor.