I would like to get some SMD solder paste for the first time and try my hand at soldering with a hot plate. I thought I would get a well known brand of solder such as Kester and there is a seller on Amazon selling it in a syringe. Amazon.com
I checked with the seller if they though it would be compatible with a dispenser like this and they think not.
I would like to use a dispenser but how do I find a quality solder that will work with a dispenser of this type? I don’t really want to buy crud that I have to just throw in the trash, and it seems likely I will end up doing that if I don’t get advice from you guys who are experienced. How do I buy a good quality solder that I know would be compatible with a dispenser that pushes the plunger with precision or a quality solder paste that has a dispenser and refills? The choices online are a bit overwhelming.
Be advised that all solder paste ages. Gravity makes the solder separate from the flux and will be impossible to dispense. You want freshly made paste. Buy from a reputable vendor, not an unknown. Keep the solder paste in a cold refrigerator to limit the separation. Warm to room temp before using.
I found that syringes don't work for me.
As an infrequent user, they dry out too fast, ending up like concrete inside within weeks.
I now use tub of the stuff and a toothpick or similar metal stick to put a tiny dab on the board.
Room temperature while applying is critical, and so is viscosity.
I mix in a few drops of IPA when too thick.
For the bigger jobs I use a stencil.
Leo..
OK I will probably need to adjust my approach and do what you do, Leo. I predict I will use 10% of a syringe of solder and try to store it in the refrigerator and come back later just to find it does not survive infrequent use. I thought the dispenser idea sure looked neat-o. It may be fun to make a motorized 3 axis syringe turner to fight the separation by gravity…
I just used 4-year-old paste (I wrote the date that I opened the container on the lid) that was stored in the fridge. It worked but was far from optimal and I had to do a lot of cleanup.
I’ve never used a dispenser like that: I started out just using the syringes and plenty of flux and it worked pretty well but it was clearly wasting solder paste. These days, on the rare occasion that I make a PCB (hence the age of my paste), I use a stencil. OSH Park has mylar stencils very cheap and they work quite well. JLCPCB has metal stencils for about the same price if you don’t mind the wait/paying extra for express shipping from China.
@LarryD
You should of course put the part on top of the paste, and press it in a bit.
Not like the video where you put the paste next to the already fitted part.
Under the part will also likely use less paste, which helps against bridging to other pads.
Under the part also acts like glue, preventing the part from moving.
I usually paste the whole board first and then put the parts on with tweezers.
One trick I have found out is how to fit multi-pin chips.
I smear a thin layer of paste on a piece of blank circuit board (or any smooth surface) with a spatula (bank card). Then hold the chip top and bottom with tweezers, and use the chip like a hair comb on the paste. That leaves a tiny blob on each pin. Then just drop the chip on the pads.
Leo..
Finally, the flux in solder paste is an organic acid. It becomes active when heated to the solder melting point. Therefore, you need to thoroughly wash the board when all done with hot water and brush with a small paint brush or tooth brush.
I have a glue dispenser, connected to an air compressor, but it takes too much time to set up for a small job. I just bought this manual squeeze dispenser.
Will see how that goes.
Through Aliexpress, because I'm not in the US, so it might take some time to report back.
Leo..
LarryD has now made me interested in using 1 ml Borosilicate glass syringes. I would like a lever or trigger dispenser tool that would match the syringes, but I may just have to make a tool for that if I want one because I think the chances of finding something that will just work are about 0%. The modified food tong looks interesting.
