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By roach
Hi All. I'm working on a surface mount project with a lot of tiny, 0603 components, and the solder paste I'm using is utter crap (for this purpose, at least). It comes out of the syringe with the consistency of cement, doesn't "stick" to pads, and I basically have to push it around with a pair of tweezers and a sewing needle. Does my paste have too much / not enough flux? Is the chemical composition wrong for this application? Can anyone recommend a better brand or type of solder paste (in a syringe. I don't need a tub of the stuff)?

Here's the paste I'm using, and it's really not working for me. ... MD291AX-ND.
By jthompso
Chipquik paste is a joke for all the reasons the OP's low cost and claims to have a 6 month room-temp shelf life, but in my opinion there is no way to may it work for serious smt assembly. Do yourself a favor and get something that will work! Besides Chipquik I've also used the following pastes:

Multicore 62/36/2 SN/PB/AG (Newark 18K6979) -- The first time I used this paste it printed beautifully and the soldered joints were impeccable...I handplace 0402 discretes on my boards and my criteria for good solder paste is no tombstoning or misalignment of these parts. With a 22 or 23 gauge needle the paste was difficult to extrude, but not impossible. The problem is that with every use this paste seemed to thicken to the point that it was no longer usable after only depleting half the syringe! (and yes this was with refrigeration and replacement needles)

Kester NO CLEAN 63/37 (Digikey KE1507-ND) -- This is all-around the best solder paste I've used. Even with a 23 gauge tip it flows easily, adheres to pads/components well, and doesn't bridge excessively. The shelf life is really good too. I go through cartridges every couple of months now, but I once used the same syringe for two years without any refrigeration. The paste still flowed as easily as when new, but it must have turned all of a sudden because I assembled about four boards where most of the discretes tombstoned before getting a new tube. All around, this seems like a perfect solder paste for either occasional use or moderate prototype work. It used to be you could only order this overnight but now digikey says "To ensure customer satisfaction and product integrity, air shipment is recommended" so maybe they relaxed this restriction.

Make sure to get plungers and syringe tips!