a good solder paste

[broly]

believe me, no one is a bigger fan of MG Chemicals, The National Treasure Loserville Doesn't Deserve But Gets (like many things the motherland has gifted us in spite of our hapless belligerence), but i don't like the 4900P SAC305

it's too hard to get out of the syringe. i don't refrigerate it, but i don't think that's the problem. it's just a tough product to get out of the syringe and i don't want to clutter my toolbox with needles or plungers to unstick the syringe, because the syringe really isn't the issue.

the stuff is good once you get it wet, but it's like a thick pasty sand that doesn't flow out easily.

any recommendations? gotta put my order in soon here.

[GilbouFR]

When you say "paste" you mean the flux ?
I use a little bottle with a kind of needle : Beeyuihf "no clean liquid solder flow" #923
I got two of those for 10 euro each. Bottle is not huge so it's easy to use :
https://www.amazon.fr/-/en/BEEYUIHF-Clean-Liquid-Solder-Electronics/dp/B0G2GTRDBG

I did try to find one of those seringes of MG Chemicals flux but seems to be easier to find in the USA.

[paulca]

Try warming the syringe on a hot plate or... a cup of hot water.

I put mine on the hot plate with the board at 40C while I get stuff sorted.  When Im about to paste, I put the needle flush against the hot plate to heat it.

The warmer paste flows easier.  Just as long as you don't get it too hot and activate the flux.

[Laval]

There are Flux syringe dispensers that help. They are made with 3D printers and can be bought on Amazon or AliExpress. I think you can get the model files on the net and print them yourself if you have a printer.

https://www.amazon.ca/Dispenser-Portable-Soldering-Extruder-Electronics/dp/B0C8B62FL4/ref=sr_1_10?sr=8-10

Like Paulca said, warming up the syringe using hot water works great.

[broly]

thanks for the tips guys, but just to be clear: it's not flux.

i have one of the tubes that dispenses flux through a syringe, and that one is OK. sometimes it can get a little tough, but it won't break the included plunger.

this is the paste i'm talking about: https://mgchemicals.com/products/soldering-supplies/solder-paste/sac305-solder/

it's a solder paste that is dispensed through a syringe. breaking the included plunger apparently is nothing new, because it is hard to get out.

i haven't tried to warm it because i didn't think that would be helpful since the compound itself is viscous and coarse. but maybe one of these gizmos you're recommending can do the trick

jeez 20 loserbux for one, when aliexpress is asking 10? dayum lol

[paulca]

If you are applying it to pads by hand, you don't need it to be fast and it wont be through a needle.  The technique is not to expect the plunger to move and solder to "squirt out" the end.  The technique is to apply a good amount of force, wait a little, then begin "extruding" a slow "slug" or solder.

It has momentum too.   When you stop pushing on the plunger it will continue to flow for a while.

Different needle sizes impact things too.  I think I use a 0.8mm needle, but you can buy a bag of needles on Amazon for a couple of dollars.  Short ones, long ones, big ones small ones etc.

Heating it up does help.  Im fairly sure the last datasheet I read for solder paste said it's application temperature was 30-35C and to warm it in water before use especially if refridgerated.

If you are dispensing it for use with a stencil... don't bother with the needle, take it off and use the bare syringe to dispense a liberal blob.

EDIT:  YOu mention you don't refridgerate it.... what does the solders datasheet say?  Usually  it will give you an "Unopened" and an "Opened" shelf life.  With/without refridgeration.  This is because the flux breaks down and effectively dries up over months.  Usually the syringes only have a 6 month to a year shelf life when opened.

If you still feel it's too thick to work with, you can dillute it with flux.  Search on YouTube you will find people who swear by this method.  No needle.  Just squeeze out a blob, squirt a good amount of fresh flux into it and mix.  Then apply it with a pick or other point.  You could also put the dillute stuff into a new syringe and it might flow faster for you.

[tooki]

When you say "paste" you mean the flux ?

No.

“Solder paste” (also called “solder cream”, mostly in the past) is solder powder (around 80-90% by weight) mixed into tacky flux.
“Soldering paste” is a traditional name for the flux paste used by e.g. plumbers and sheet metal workers. It is not a term traditionally used in electronics.
“Flux paste” is the name for traditional electronics fluxes in a stiff paste.
“Tacky flux” is the name of more modern electronics fluxes that are thinner, sticky pastes.

[tooki]

it's too hard to get out of the syringe. i don't refrigerate it, but i don't think that's the problem. it's just a tough product to get out of the syringe and i don't want to clutter my toolbox with needles or plungers to unstick the syringe, because the syringe really isn't the issue.

the stuff is good once you get it wet, but it's like a thick pasty sand that doesn't flow out easily.

any recommendations? gotta put my order in soon here.

”Thick pasty sand” sounds like dried-up paste. You really should store paste refrigerated to extend its life; most pastes have only a 6-12 month official shelf life even refrigerated, and unrefrigerated reduces it further. (Refrigerated, they usually last a lot longer than the 6-12 month guarantee.)

However, what I really urge you to do is to buy conical (aka tapered) dispensing needles. They reduce the force needed massively. The extra-long, straight needle MG includes is really rather suboptimal, as the friction loss (loss of pressure due to friction along the inside of the needle) is significant.

Dispensing needles are very inexpensively bought from AliExpress. I bought an assortment of conical tips a while back, and I like 22ga (blue) best for solder paste and flux. You can always snip the tip a bit if you need it bigger. Make sure they are luer-lock, since luer-slip will just pop off under the pressure of a thick paste. (Almost all conical tips are luer-lock, but just make sure.)

With no needle attached to the syringe, the paste should flow out easily with only modest force. If it requires significant force, it’s dried out.