Plunger, needle tip & cap for flux & solder paste syringe - where / which to buy

[Rooster Cogburn]

When you buy solder and/or flux paste, it generally comes in a 10/30cc syringe like this:




In their infinite wisdom, (most) manufacturers decided to save a few cents and not include a needle tip, cap for the tip & plunger . I'm a bit lost on how to get these syringes into a usable state.

Searching a bit on eBay / AliExpress, I see a lot of options:

https://www.aliexpress.com/wholesale?site=glo&g=y&SearchText=syringe+needle

Getting a needle tip seems to be easy enough, lots of good looking options. But they never seem to come with caps. I of course don't want flux to smear all over my soldering consumables drawer or have my solder paste dry out. I don't see individual plungers on sale much, and it's not clear if they'd actually fit. There seem to be different mechanism to attach them. You can buy complete kits, but transferring a syringe of solder paste seems super messy. Why would they even bother putting it into a syringe if the first thing you have to do is transfer it to another.

Seeing as this decidedly not-ready-to-use packaging the industry standard I'm sure somebody here has solved this issue and can hopefully point me at the right set of affordable Chinese parts to make 10cc / 30cc flux & solder paste syringes actually work. Thanks

[Ian.M]

Pros use motorised or pneumatic syringe drivers, and use up a syringe of paste before it can dry out, and the needle dimensions are application and syringe driver specific (and temperature dependent) so all the extras that are nice for the hobbyist or occasional user would just end up in the bin as soon as the pack was opened, so the volume market wont pay for them.

There was a thread on this a few years back.  Try https://www.eevblog.com/forum/reviews/solder-pasteflux-manual-syringe-applicator/

Affordable + Chinese + working is a low odds combo

You can always cap straight needles with a slice of foam plastic wine cork you've bored a fractionally undersized hole in (so the needle doesn't plug itself with compressed foam).  Conical 'needles' are more problematic - try bluetack for short term storage leaving a tiny bit of paste/flux on the tip so it doesn't block it.   Long term, all are best removed, the syringe capped off and if you aren't going to thoroughly clean and flush the needles for dry storage, stored in a small sealed vial with a little IPA in the bottom to keep the flux/paste moist + a disk of plastic with legs folded down to keep them out of the IPA so it doesn't wash the flux out of the paste.

[Rooster Cogburn]

I really just want a proper, working syringe.

For instance, if you buy flux from MG Chemicals they do the right thing and give you a working tool, a full syringe with a plunger, needle and a cap. That's all I want. These solder paste applicators are complete overkill for me for the few times I need paste and I've never seen them used for flux gel. No need for a bulky contraption to squirt a glob of flux on your PCB. I guess I could poke my syringe into a piece of cork or whatever, but that seems sooooo janky. I want a cap like the one that comes with MG Chemicals flux. I also don't see why any of this would be expensive or should not be sourced from China. We're talking about a few really simple pieces of plastic & metal to complete a syringe (that 99.999% sure been manufactured in China for 5c anyway), that doesn't need to be sourced from some domestic specialty artisanal syringe store.

I want to buy this:



Minus the syringe of vaseline

[Ian.M]

Its not expensive, but the Chinese market is extremely competitive and the manufacturers are trying to squeeze the last fen (cent) out of the unit cost.  Kitting the syringes with prototyping accessories is an extra expense and time cost for resellers breaking case lots, and there's obviously not enough demand to make it commonplace, so it isn't going to happen unless you pay a considerable premium. 

Also 99% of the resellers have probably never spent an hour soldering in their entire lives so you can bet that if they did kit them with accessories you'd be complaining about the crappy plunger, needle and cap.

[Psi]

search aliexpress for dispensing needle syringe kit
You'll find lots of them for cheap.
if you've never used aliexpress before, just make sure you pick a seller with lots of previous sales and a feedback percentage over 95%.  The free cheap/shipping usually takes 2-4 weeks.  EMS 1-2

etc https://www.aliexpress.com/item/SMT-Solder-Paste-Adhesive-Glue-Liquid-Dispenser-kits-pack-glue-dispensing-syringe-dispensing-tips-dispensing-needle/32618261912.html
Those are the smaller syringes though, depends what you want.

[Ian.M]

You'll probably also want a strong female-female Luer lock coupler and an appropriate diameter dowel set in a block of wood as you can bet the dispensing syringe kit plunger wont fit the piston of your flux or paste syringe properly so you'll need to transfer product to a working syringe, which will also help with paste shelf life as you wont need to warm up the bulk syringe to use it, so can keep it sealed and refrigerated >99% of the time. 

A small diameter (low CC) syringe is *MUCH* easier to dispense from controllably manually without special tools so you may be better off transferring to 1ml or 2.5ml sryinges (size depending on your daily usage) anyway.

[Rooster Cogburn]

This is not about cheap Chinese no-name solder paste / flux. Frustratingly, more often than not the cheap Chinese stuff actually includes the proper accessories (see the picture I just posted).

When you buy Amtech Flux from Louis Rossman's store, there's an option to just include a needle tip and a plunger:

https://store.rossmanngroup.com/amtech-nc-559-v2-30-cc-16160.html

It's perfectly usable in its 30cc syringe. Amtech doesn't sell their flux with the 'accessories' included, and I doubt Louis transfers it to a different Syringe and prints a new Amtech label on them. So clearly you can buy those accessories somewhere. I'd really like to avoid transferring flux / solder paste between syringes, that just seems like a messy PITA. I see a lot of needles that I could buy, but I don't see plungers or needle caps.

Sure, I could buy this thing:

https://www.aliexpress.com/item/Free-Shipping-5pcs-syringe-metal-dispensing-connector-dispensing-needle-connector/32822151182.html

and then a bunch of those:

https://www.aliexpress.com/item/10ml-Syringes-with-14Ga-1-5-Blunt-Tip-Needle-and-Storage-Caps-Great-for-Glue-Applicator/32859419087.html

(hey look, they even have caps!)

and then hope I can get my flux and solder paste into them without making a mess. But wouldn't it be much easier to just screw a needle tip & plunger into the syringe the stuff's already in? I don't run a repair shop, I don't solder 8h a day, don't need any fancy dispensers. I'd be 100% happy if I could use solder paste or Amtech flux the same, comfortable, simply way I use the MG Chemicals flux that comes in a complete syringe with needle, cap & plunger.

So far the best option I can think of is to buy cheap Chinese flux with all the parts included and just throw the flux away

[nanofrog]

You can buy plungers quite inexpensively (you may have to cut the cone bit off to make it flat).  Lots of sources to find them, such as eBay, Aliexpress, DX, Banggood, ... And as mentioned, Louis sells them in his store as well. 



If you have a 3D printer, there's an Injection Plunger for Soldering Flux Syringe project on Thingverse you could reproduce (files are available). 



Another consideration would be a syringe gun (they come in 10 & 30ml sizes).

Here's a 30ml Manual Syringe Gun you'd need for your Amtech flux. 



As per needles, I'd suggest getting an assortment kit to see what you like. Do note that the plastic cone versions are actually easier to get the material to move out of the syringe (particularly with solder paste; flux is easier to push).

Some examples:

• 140PCS assorted 1/2-inch luer lock End S.S. Needle dispensing Tips|(14G,15G,16G,18G,19G,20G,21G)*20| Dispense Tip set with case
• 120PCS TT assorted Plastic Conical Smoothflow Tapered Needle/Tips(14G,16G,18G,20G,22G,25G)*20 | Dispense Tips set with case

As per capping them off, a bit of white plastic pencil eraser does nicely IME. 

[Skashkash]

In general, I find the smaller 1cc syringes easier to work with on the bench for both fluxes and solder paste. Less pressure to dispense, and very easy to fill from the reverse end from a larger "bulk source" syringe. I also prefer to keep the bulk of the pastes in the fridge to extend shelf life.. 

I buy the 1ccs  in quantity, I don't re-fill them, just discard when empty or messy. 
https://www.ebay.com/itm/100-1ml-Syringe-Only-with-Luer-Slip-Tip-Sterile-Disposable-Latex-Free-1cc-NEW/282457225813 

And everyone has a different preferred tip style and size.

Dispensing tips clog and and need cleaning. Easier to just toss in the trash and stick on a new one on. Cheap enough.

I got in some sample assortments and then just bought a large quantity of the ones i found worked best for me. 

https://www.ebay.com/itm/35Pcs-Dispensing-Needle-Tip-For-Liquid-Dispenser-Adhesive-Glue-Syringe-Kit/322443595096
 





 

[Rooster Cogburn]

You can buy plungers quite inexpensively (you may have to cut the cone bit off to make it flat).  Lots of sources to find them, such as eBay, Aliexpress, DX, Banggood, ... And as mentioned, Louis sells them in his store as well. 

I had absolutely no luck finding any plungers even though I spend quite a while searching on BG, AliExpress, eBay. On eBay there was a seller that wanted >10EUR for shipping a single plunger, didn't find any on BG, AliExpress had a 500pcs lot or something impractical like this. Buying from Rossmann and other US sellers is unattractive for me due to shipping & customs. I didn't find a single plunger on sale that wasn't massively more expensive than just buying cheap flux/paste with the plunger included

Another consideration would be a syringe gun (they come in 10 & 30ml sizes).

Here's a 30ml Manual Syringe Gun you'd need for your Amtech flux. 

Mostly attractive because then I wouldn't need a plunger ;-)

As per needles, I'd suggest getting an assortment kit to see what you like. Do note that the plastic cone versions are actually easier to get the material to move out of the syringe (particularly with solder paste; flux is easier to push).

Some examples:

• 140PCS assorted 1/2-inch luer lock End S.S. Needle dispensing Tips|(14G,15G,16G,18G,19G,20G,21G)*20| Dispense Tip set with case
• 120PCS TT assorted Plastic Conical Smoothflow Tapered Needle/Tips(14G,16G,18G,20G,22G,25G)*20 | Dispense Tips set with case

As per capping them off, a bit of white plastic pencil eraser does nicely IME. 

There's a ton of options regarding needles. Good idea buying a kit so I can try out all sizes!

[Ian.M]

Unless things have changed a lot in the last decade or so, I think you'll find that captive plungers are often  not compatible between different brands of syringe as the plunger to piston seal interface isn't well standardised.   The plungerless syringes intended for use with automatic dispensing and compact syringe driver systems will have fairly good standardisation of the plunger/piston interface because compatibility is an obvious requirement, but your wun-hun-lo syringe of vaseline's plunger is quite likely not to fit the plungerless syringe from Amtech or other reputable source's piston well enough.  That leads to the plunger coming loose when the syringe is part used, usually when you pull back on it to stop drool, then when you attempt to re-engage it with the piston, there's a fair chance the piston will capsize, at which point you have a FUBARED mess that you can either trash, or attempt to remove the capsized piston with forceps so you can scrape the product out with a spatula and transfer it to a jar.

   Been there, done that and got the (stains on my) teeshirt! 

Nanofrog's suggestion of cutting the mushroom end off to make it non-captive may work well enough if you are careful and lucky and if you've got a 3D printer that suggestion  looks like its worth a try , but decanting into a smaller syringe isn't really that much hassle and with any common sense is nearly mess free.   The Luer lock coupler holds the two syringes nozzle to nozzle and the dowel in the block of wood sits on your bench so you can easily push the pistonless syringe down on it with one hand till the small syringe is 2/3 full, while your other hand eases back the small syringe plunger. Take it off the dowel and pull a slight vacuum with the small syringe, before disconnecting the coupler, plungerless side first and you'll get minimal mess with only the coupler to clean unless you are decanting ridiculously runny flux   

Unless its *very* runny I don't like filling syringes from the back as its very difficult to avoid air bubbles and even a small bubble results in poor control and a tendency to drool when you stop pushing.

[nanofrog]

I had absolutely no luck finding any plungers even though I spend quite a while searching on BG, AliExpress, eBay.

I found one on eBay for $4.99, but shipping to Germany was just shy of $16. 

I also searched using the term piston, and didn't have any luck that way either. So you may end up having to buy an entire 30ml syringe to get the part you need. 

...[re Manual Syringe Gun]...Mostly attractive because then I wouldn't need a plunger ;-)

I'll eventually break down and buy one of these someday. 

There's a ton of options regarding needles. Good idea buying a kit so I can try out all sizes!

Best way to find what works best for you IMHO. 

[nanofrog]

Nanofrog's suggestion of cutting the mushroom end off to make it non-captive may work well enough if you are careful...[snip]

Unless its *very* runny I don't like filling syringes from the back as its very difficult to avoid air bubbles and even a small bubble results in poor control and a tendency to drool when you stop pushing.

FWIW, the cone/mushroom end isn't compatible with the piston seals used for dispensing products IME, so something flat works much better. A razor knife with a fresh blade should do nicely.

I also like the idea of filling smaller syringes, but I'm with you on the air bubbles issue from filling them from the back end. Fortunately there is a Female Luer Lock to Female Luer Lock adapter/coupler, so that should solve the problem. BTW, I checked and this seller does ship to Germany if you're interested.

Stainless:


Disposable type:


I'll be buying one of the stainless couplers I linked. 

[Skashkash]

I've not had too much trouble with air bubbles from filling from rear filling small syringes, but the amounts i'm using are small.

I've been using one of this style re-usable plungers for years. It came in a paste sample kit from an old job, and has been pretty universal.  I could certainly use a few more in different sizes. 

http://www.adhesivedispensers.co.uk/handplungers.htm 

I wish I could find a cheap source of them.   

[nanofrog]

I'd seen those before, but I couldn't recall the terminology. So thanks. 

I found a 3pk. of the 30ml size on Grainger, and they they want $133.00 for it (here).  The 10ml come in a 2pk. that goes for ~$73. Their sister site, Zoro, is better on pricing, but still not what I'd call reasonable ($86.99, here). The 10ml 2pk. goes for $51.95. 

Buy once, cry once I guess, but the syringe gun is looking even better at those prices ^. 

[Rooster Cogburn]

This is just a such a stupid problem

I think a very good point made by Ian.M is that there's no standard way to attach the plunger to the piston. So there'll be no way to actually pull back on the plunger, and in my experience that's pretty useful with any syringe dispensing viscous gel. And harvesting plungers from existing syringes is also probably nasty because they generally don't just come out, and as Ian.M said, pushing onto the piston with some kind of cut-off plunger might wedge/flip the piston. And it seems you can't easily buy plungers, except by buying Chinese flux with plungers and throwing the flux away Like this:

https://www.ebay.de/itm/Mechaniker-UV-Hartbare-Lotmaske-Loten-PCB-Reparatur-Grune-Farbe-10cc-Plunger/192437551673?hash=item2cce2c0239:g:QN0AAOSweLBaacbo

Also, why are these female-female couplers so expensive? ;-)

The Amtech business strategy: "Let's make our product very hard to buy and then ship it in a container that requires hours of hunting down accessories on AliExpress to actually get something out"

I'm beginning to think the best strategy here is to buy a selection of tips, a few syringes and a luer lock coupler. Probably quite OK for the flux but I'm a bit worries about the thicker solder paste.

[nanofrog]

Also, why are these female-female couplers so expensive? ;-)

The Amtech business strategy: "Let's make our product very hard to buy and then ship it in a container that requires hours of hunting down accessories on AliExpress to actually get something out"

I'm beginning to think the best strategy here is to buy a selection of tips, a few syringes and a luer lock coupler. Probably quite OK for the flux but I'm a bit worries about the thicker solder paste.

Regarding the couplers, my guess is that they're not all that common, so no small quantities are available (sold by the case = too expensive for our purposes). And although the stainless steel model is expensive initially (~$9 shipped to you), it's not disposable so you only have to purchase the one. It does require cleaning though (bit of a PITA, but livable IMHO).

Not sure why genuine Amtech products are so hard to find, but I've always avoided them due to this issue (almost certain I'd get a fake).  As a result, I've stuck with Kester RF741 flux (good stuff). Given your location, I'd think Henkel/Loctite products should be readily available to you.

The steel needles would be fine with the flux, but are much more difficult to use with solder paste. This is where the plastic conical tips come in handy as they're a LOT easier to push solder paste out (you don't have the bottleneck right at the Luer Lock tip you do with the metal ones).

So if you can get some 30ml syringes at a reasonable price, go for it. Just be sure to get the plastic conical tips for solder paste, and you'll be fine.

As per a dispenser, the Manual Syringe Gun seems to be the way to go (nice balance of cost/performance @ $30 shipped).

[Rooster Cogburn]

Those http://www.adhesivedispensers.co.uk/handplungers.htm things look fantastic, but WTF prices...

I've been using alcohol no-clean with low solids so far as it's reasonably effective and leaves very little residue that's trivial to clean, but I wanted to give gel flux a shot. I bought some of this:

https://www.amazon.de/MG-Chemicals-No-Clean-Flussmittelpaste-Spritze/dp/B00425FUW2

It's fantastic. Comes it a syringe, ready to use, even has a cap (mind-blowing!). I love how I don't constantly have to re-apply flux. When working out solder bridges or when working on a board that's heated from a hot air station etc. the alcohol based no-clean is just gone after seconds.

The downside of the MG Chemicals stuff is that it's pretty much the stickiest substance one earth. I feel I have to wipe down the PCB with alcohol 5x and then it's still sticky. It gets on your fingers, makes parts stick to your tweezers, your ESD mat gets gunky. Supposedly the Amtech stuff is better. I'd like to buy some Amtech from the European distributor and compare, but first I have solve the 'syringe issue'.

[nanofrog]

Do you know someone with a 3D printer?

Maybe bring a 12pk of beer you can share while waiting on it to finish. 

[Rooster Cogburn]

So I bought an assortment of syringes, needles & a f-to-f coupler. I'll report back in a month if this worked out

Thanks a lot for your suggestions!

[nanofrog]

So I bought an assortment of syringes, needles & a f-to-f coupler. I'll report back in a month if this worked out

Thanks a lot for your suggestions!

You're welcome.