Needle and plunger for flux syringe - Page 1
Forum section: electronics / general

author: Axk
author_rank: Regular Contributor
timestamp: February 21, 2019, 07:00:15 pm
content: Where do you get these if they don't come with the flux?Just bought what is presumably Flux Plus NC flux and realized it has no plunger and needle with it.Can probably retrofit a regular disposable syringe needle cut with a knife and a plunger from the same source.

author: GreyWoolfe
author_rank: Unknown
timestamp: February 21, 2019, 10:54:02 pm
content: I buy cheap small squeeze bottles with syringe needles on them off of evilBay. I have used regular syringes in the past and I have much more control with the bottles. I also put a bit of a crimp in the end of the needle to reduce the amount that comes out so I have better control on how much I dispense.

author: wraper
author_rank: Unknown
timestamp: February 21, 2019, 11:13:16 pm
content: Quote from: GreyWoolfe on February 21, 2019, 10:54:02 pmDo you talk about liquid flux? It is rather stupid to put it into syringe. On the other hand OP asks about gel flux. Not only it comes within a syringe to begin with, you won't be able to squeeze it out from the bottle.

author: Axk
author_rank: Regular Contributor
timestamp: February 22, 2019, 08:45:00 am
content: Doh!Just notice a typo. It is in a syringe. Just no needle with it.*has no plunger and **needle** with it.

author: GreyWoolfe
author_rank: Unknown
timestamp: February 23, 2019, 03:02:36 am
content: Oops, I should have checked what you had. I use liquid flux not gel.

author: sleemanj
author_rank: Super Contributor
timestamp: February 23, 2019, 07:03:28 am
content: The syringe flux comes in (and paste) is typically for air-dispensing so it doesn't have a manual plunger.I just transfer it to a normal 10cc syringe with a plastic "dispensing needle" tip. You can get such a syringe from your local pharmacy probably for a couple bucks, or online.

author: KL27x
author_rank: Super Contributor
timestamp: February 23, 2019, 09:04:10 am
content: QuoteI have suggested syringes to some of the people I do work for. They have all voiced a preference for the squeeze bottles. But whenever I am down there and try to do any soldering, it's guaranteed the needle on the flux bottle is clogged. So I don't get it. When I mention this to the same guy who said he preferred bottles, he admits he pretty much never uses flux.The crimp you put on there to slow the flow is a good idea. I stuff the wad of cotton from a Q tip into the plastic needle to regulate the flow with the syringe. The tip won't dry out if the syringe is hanging point down, and I usually keep it clipped to the side of my microscope that way. Even if the tip dries out because I left it lying around for a week or three, a good push gets some solvent in there and gets it working, again, in just a few seconds. I've used the same tip for probably up to about 10 syringes, or so. It only ever dies because the plastic eventually gets mangled unscrewing it from the empties with pliers!I cut the tapered needle back to produce a good wide flow to flood pads. That's my main modus of operation with a factory PCB. But if neatness counts, say on a homespun board without soldermask, I clip the syringe in its home and depress the plunger to produce a bead of flux. Then I touch the sharpened point of a Q tip or other pointed implement to it.OP, I buy syringes in boxes of 100. Costs like 20 cents per, here. FWIW, I have transferred solder paste into syringes, so gel flux should be much easier. Pop the plunger out the back. Screw the cap on. Then squirt the flux in from the back, using a stick or whatnot in lieu of the regular plunger. Then smack the capped nose of the syringe on a hard surface to get the air bubbles to rise to the surface and escape. If you put a small wire in when you reinsert the plunger, you can avoid making an air bubble back there. Just lower the plunger until about all the air is gone, then withdraw the wire. Any air back there introduces some sponginess in the dispensing.

author: Axk
author_rank: Regular Contributor
timestamp: February 23, 2019, 07:50:40 pm
content: I ended up transferring to a regular 10cc syringe. Connected the front of regular syringe to front of the flux syringe with a short piece of drop counter tubing and sucked with the regular syringe and it sucked it all out of the flux syringe.The same with the needle. Took the needle from the regular syringe, marked a groove with wire cutters and then it easily snapped, finished off the end with a file.