I'll try to make some sense out of your choices. Basically Solder has a solidus and liqudus point. 63/37 solder is cool because they are the same. So, for a process using lead this is almost mandatory for SMT work and it's really easy to work with. It tends not to form bridges like 60/40.
60/40, again a lead process; when you heat the joint, it stays liguid for a while. Remember c=soldering wires and having to hold it steady?
The other class is the Sn96.x variety. This significantly increased the temperature. Tin does have the tendency to form wiskers.
I'm a novice in SMT work, but my first removal was a 64 pin processor and I used 63/37. I used the cut and remove method and soldered it upside down. Meaning the chip was facing down while I was soldering with the iron effectively over my head.
My first SMT paste was the Bismuth alloys of Bi58/something and I like it. It's low temperature. It needs to be stored in the fridge and warmed up when you want to use it. I havn't done any stencil stuff yet. I would consider lifetime to be important to be if you are using it with a stencil.
Another reminder is that the paste is usuallly shipped in a cold pack and 2nd day or so, so don't make the package heavy.
You should look at www.chipquick.com. Digikey has the chipquick Bi58 allow, but I didn;t see it on chipquick's website.
I too have a solder/de-solder/hot air station from circuitspecialists.com and an over the head LED lighted magnified visor. I can see the advantage of a bifocal microscope with a 5" or so working distance since I used them at work.
Cleaning the flux residue has always been an issue. Water is easier than solvents.
On Monday, August 18, 2014 6:16 PM, "qz9090@... [Homebrew_PCBs]" <Homebrew_PCBs@yahoogroups.com> wrote:
As I continue to assemble my SMT tools, supplies and processes, I was looking at acquiring some solder paste. Unfortunately, there are several kinds of solder paste? What are the pros and cons? Should I consider water soluble paste? Does the tin vs lead vs copper mixture have a significant impact on my selection?It looks like shelf-life is limited, should that be a factor in my selection?Any input on this matter would be greatly appreciated.Thanks.FP