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View Full Version : Dispensing solder paste, where to buy syringe etc?



Agent_24
13-02-2012, 10:54 AM
Now that I'm starting to get into working with SMD parts, I want to get a syringe and tips to get solder paste onto the PCB.

I bought a jar of solder paste a while back, and would rather use it than buying a whole new lot already in a syringe.


Apparently plastic tapered tips\needles are better than metal (less pressure needed): http://www.microbuilder.eu/Tutorials/SMTSoldering/SolderPasteByHand.aspx but I have no idea where to buy them, or even metal ones (at least, in small quantities\prices)


RS Components at least does seem to sell them, but only if you want to buy them in bulk for at least 100 for $100 or so - which is of course overkill.

eBay has better prices, but I'm not sure if that would work, I wouldn't be surprised if the NZ customs are paranoid about any kind of needle\syringe related items, and would throw them away.

Besides, I want to try different sizes, and most sellers seem to have them in packs of 50 or more which is again overkill.


Anyone here got any good ideas?

Zippity
13-02-2012, 11:42 AM
Try http://www.hobbiesplus.co.nz/paste-flux-wrightway-p-763.html :)

Agent_24
13-02-2012, 07:08 PM
Try http://www.hobbiesplus.co.nz/paste-flux-wrightway-p-763.html :)

Thanks but I want solder paste, not paste flux. Also, the tip of that looks a little big.

Some SMD component pads are <=1.0mm wide, and that looks like it would swamp them.

SP8's
13-02-2012, 07:21 PM
May sound silly ... but go ask a dentist. They use a disposable syringe with a twisted (like the tip of a corkscrew) tip to flush out abscesses (root canals) after drilling through the tooth ... I know from personal experience and have a couple of the syringes myself. They come in extremely handy for applying small amounts of grease, oil, pastes, etc into tight places.

forrest44
13-02-2012, 07:26 PM
As far as I know with a syringe it's hard to get the right amount to come out. If you're doing more than a few boards, just get a stencil made up. The way I've applied solder paste for prototype boards is to apply the paste using a very fine tip from a pair of tweezers, under a microscope. This has worked (for me at least, YMMV) for parts down to 0.5mm pad pitch.

Do let us know how you get on

somebody
13-02-2012, 07:29 PM
Pharmacies sell them - including the ones with a curved plastic tip.

Agent_24
14-02-2012, 11:34 AM
As far as I know with a syringe it's hard to get the right amount to come out. If you're doing more than a few boards, just get a stencil made up. The way I've applied solder paste for prototype boards is to apply the paste using a very fine tip from a pair of tweezers, under a microscope. This has worked (for me at least, YMMV) for parts down to 0.5mm pad pitch.

Do let us know how you get on

I've tried that method with a very small screwdriver etc and it just made a mess and was quite hard to do. Didn't think to try tweezers though.
At the moment I think stencils would be overkill, because I'm not even thinking about doing any sort of production run, just one-off boards and rework.


Anyway, to continue the story... I bought a syringe from the pharmacy yesterday (and now I'm thinking they probably think I'm a drug addict :lol:)

Came with a 26 gauge needle that I ground down with my Proxxon tool to make it flat on the end. I read on Wikipedia that 26 gauge = 0.26mm inner diameter which seemed to be what I wanted, but when it came to actually trying to squeeze the solder paste out, it was practically impossible.

I see now why the author of that site says: "Personally, though, I have a preference for the plastic tips because: I find it takes a lot less pressure to start the flow of paste with the 'conical' plastic tips" - This is a very accurate statement!

So until I find a good source for the plastic ones it looks like I'm a bit stuck for now...

kahawai chaser
14-02-2012, 03:06 PM
I use to use fine syringes and pipettes when working with micro samples of chemicals, inks, and adhseives. Their are plastic, metal, and glass including disposables, and come in different styles and size. Use to buy from chemical suppliers like lab supply (http://labsupply.co.nz/) or global science nz. (http://www.globalscience.co.nz/) May have what you want. You probably want a vacuum assisted set up, of which rubber bulb glass/plastic pipettes (purge air then easily squeeze the liquid out) were ideal for that. I'm sure I have seen some at chemists or a vet once.

pine-o-cleen
14-02-2012, 03:51 PM
Also any farm supplies place, or vet.

forrest44
14-02-2012, 09:07 PM
hmm you could try applying it using a (non-hollow) needle tip or pin... do you have a microscope?

Agent_24
15-02-2012, 12:18 PM
No, don't have a microscope (at least not one that would be suitable, anyway)

I had another, longer look on eBay today and found these: http://www.ebay.com/itm/Adhesive-Injecting-Pinheads-for-Electronic-DIY-6-Size-/370459994458 - which seem to be just what I need.

I guess we'll find out in two weeks or so if they work (should do though, otherwise that website I linked to earlier is a pot of lies!)

Zippity
17-02-2012, 12:58 PM
See Connect's latest catalogue Issue no 4 28 Jan - 27 April page 16 http://nz.element14.com or call them on 0800 90 80 80

Agent_24
17-02-2012, 02:28 PM
Thanks but I don't want a paste or gel flux by itself at the moment - I want to dispense solder paste, which is basically small (say around 30um) balls of solder suspended in a paste flux.

I don't really want to buy a $20+ syringe of flux and squeeze all the flux out either, then re-use it, and besides, the nozzle on that one is likely too large and thus I would still have the problem where I don't have the nozzle I want.

Now that I have finally found and ordered some cheap and suitable nozzles from eBay I think I am all ready to go as soon as they arrive, hopefully!

Agent_24
22-02-2012, 12:52 PM
I received the plastic tips from eBay today. Quite fast delivery (only 1 week) compared to the usual!

Will test them out soon...