Loctite 1993881 Gray GC 10 Henkel Solder Paste, 500 g

This solder paste is thick and sticky! If you have a pick and place machine and issues with parts not staying on the board this is the one to use. Cleanup with Isoprop is not too bad if you don't let it get dry. Solder paste stays good on PCB for a couple of hours (@72F, 40% humidity) before it completely dries out.If you let this solder paste dry out on your stencil be prepared for difficult cleanup. I would not recommend this for hand soldering as it's way to thick for that. I would not use this solder paste for boards with parts smaller than 0402, the balls are too large for that.

I bought this expensive solder paste _from the manufacturer_ in March, 2020 because it is advertised as having a 1-year shelf life: "LOCTITE GC 10 is stable at 26.5°C for one year"Maybe it does, but 8 of those 12 months went by sitting in the manufacturer's warehouse. The item I received was manufactured in July 2019, and expires 4 months from now - if it was stored in temperature controlled environment! If not, and it was stored in an uncontrolled environment ("at temperatures of up to 40°C for one month"), who knows? It may already be out of spec, dumped on Amazon to keep it out of their other sales channels....I expected to get a new item with 12 months of usable life left. This feels like bait and switch being used to clear out old inventory that wouldn't otherwise be accepted by their regular high volume customers.

I've been using this paste for about six months now, and I feel like I know it pretty well.It's SPECTACULAR for prototyping work and anything else that doesn't involve a stencil. For example, if you're dispensing from a glue dropper (like this one:  Signswise Solder Paste Glue Dropper Liquid Auto Dispenser Controller For SMD PCB ), this stuff is hands-down the best paste on earth. So good that I've stopped using all other paste. I just leave a dispenser full of GC10 hooked up to the machine and always use that, even if the application allows for leaded paste -- not having to deal with refrigeration is worth it.Now, the bad stuff.First, some brief background: SMT stencil thickness is chosen based on the "area ratio" -- this is the area of the interior of the apertures divided by the area of the opening. Note that the numerator here is the perimeter of the hole multiplied by the thickness of the stencil. Divide that by the denominator (area of the opening) and you get the area ratio. IPC says this should be no larger than 0.66. Basically there's a "fight" between the board and the stencil when they separate -- which grabs the paste. You want the board to win, so you need the stencil sidewalls to have no more than 66% of the area of the board to ensure that the stencil "loses" the fight. With Kester EP256 (my favorite paste except for the fact that it needs refrigeration) I've found that metric works great.Unfortunately the GC10 paste is very, very, very sticky -- the stickiest paste I've ever seen. It's also high-viscosity, although not the worst. This means that if you've got a thick stencil (say, 0.2mm or thicker) or you're above 0.40 area ratio the first print will work great, but some paste (maybe 10%) will stay stuck to the aperture sidewalls. It's not enough to cause a bad FIRST print. The problem is the SECOND print. That paste on the sidewalls causes them to clog on the second print.So if you have an area ratio above 0.40 or so you need to clean the stencil after EVERY print. This is a deal-breaker for most people. But what makes it even worse is how darn hard this paste is to clean! Normal solvents don't seem to break the paste down (unlike EP256, which basically dissolves in acetone). You have to scrub it out of the apertures with some sort of mechanical action. Ugh. Pretty miserable. Loctite recommends a propanol-based solvent, but honestly it doesn't work much better than acetone or IPA, and it sure stinks a lot worse.We were trying to use this paste to reball BGA chips, and it was a total nightmare for that. But for ordinary SMT assembly with coarse-pitch parts it works great, just don't push the limits on pitch or area ratio.As a final note, Amazon seems to be in a bad habit of shipping paste that's only a month or two away from expiring (I got a jar with 45 days left). Not good. Amazon, please indicate the minimum shelf life remaining on the product you sell as "new". Thanks.Summary: if you're using a very very thin stencil (0.10mm or thinner) or have an area ratio of less than 0.40, this will work; otherwise, stay away. For prototyping or very thin stencils with plenty of area ratio headroom this stuff is great and delivers on all the promises.

GC10 works amazingly well.

Received product today and product was expired on July 10, 2020. Batch number OX9G003145