Solder paste tubes and plungers - Page 1
Forum section: electronics / beginners

author: Wolfie
author_rank: Contributor
timestamp: November 11, 2016, 09:05:34 pm
content: I am just starting with SMD and as such solder paste (syringe style) is new to me.I picked up a pair of tubes if Indium. Surprisingly to me, they came without plungers. Ok, I found a site that has plungers and I find the pluger costs as much or more than the solder! And, I got to thinking, being a DIYr, I can make my own. I should have no problem designing and printing a plunger. But I need some info first.The tubes came with a rear cap:Inside there is a white plug:So, before I go and do something stupid, is this white plug supposed to be the tip of the plunger or is it supposed to be removed and replaced by a plunger? I just don't want to rip it out if its not supposed to be removed. And if not to be removed then I presume the plunger snaps into it somehow.And while on this about paste...would anyone kindly decrypt these symbols:And I lastly, anyone have a good inexpensive source for dispensing tips? What diameter do yall suggest as a good starting place?I am keeping them double bagged (and inside the packing envelope in the back of the fridge until I am to to the point of using them. It seems recommended that you keep unused paste chilled when not being used to extend the shelf life.

author: Floyo
author_rank: Regular Contributor
timestamp: November 11, 2016, 09:17:40 pm
content: Normally these syringes are used on an air dispensing system, the air is the "plunger" and pushes the white bit down. This is done so you don't have to put the (considerable) force on the syringe by hand causing it to jitter all over the place and making a mess of the board, you just press a foot pedal and out comes the paste. You can of course make a standard plunger, which will work but probably be kind of hard to hold comfortably, or you could figure out some kind of mechanical leverage like a caulking gun.As for the symbols, have a look here.It basically comes down to "don't eat, inhale, or dispose of improperly", simply put.Needles can be readily found on ebay in all shapes and sizes, queries like "dispensing needle" and "dispensing needle bent" will give you all the usual suspects.Edit: The terms "glue gun single" and "glue gun manual" also seem to bring up some affordable pistol-style syringe plungers. As usual with cheap ebay stuff, quality may vary

author: tautech
author_rank: Super Contributor
timestamp: November 11, 2016, 09:32:36 pm
content: A trip to your local nurse, doctor or vet with the paste tube in hand and a pretty please should get you a used plunger from a disposed used syringe and a large gauge needle too.Shorten the needle with a cut off blade, deburr and you should be good to go.Paste consistency can be a problem with hand (manual) dispensing, be sure paste is to room temp first.

author: Wolfie
author_rank: Contributor
timestamp: November 12, 2016, 03:07:56 am
content: Appreciate the chart icon chart and the other info you two!I was completely aware it was not something I wanted to put on mashed potatoes or lick my fingers after handling. I am a reloader and avid shooter so I know about lead safety and all that and I had assumed paste based solder was likely more hazardous than wire solder due to its physical nature. But always a good idea to check symbols you aren't familiar with.I know there are needles all over to be had. Problem they come in lots of diameters. I was asking what is an appropriate diameter for solder paste? At least for someone starting out.What is the proper disposal methods for consumed tubes? I would have to assume the toxins (lead mainly I assume) would still be present. What do yall do with them?So reading yall's replies it seems like these may not be the best choice for hand dispensing and probably not the best choice for a SMD first timer? They were only $12 so its not a critical loss if thats the case. And if it is the case do yall have a good recommendation for a good beginning solder paste?

author: tautech
author_rank: Super Contributor
timestamp: November 12, 2016, 04:32:15 am
content: Quote from: Wolfie on November 12, 2016, 03:07:56 amGreetings gunny, me too.QuoteIt's not so much for newbie needs, it's about being large enough to have the paste flow with the little real pressure you can apply by hand. A fiddle I had with the stuff (was given a 500g tub ex production (date expired)) I found the small bore syringes worked best by hand as you can get more pressure relative to diameter by hand.OTOH, Paste is best reserved for reflow ovens and the like, even with hot air you can shift components from their pads if great care is not taken.For one off PCB's and prototyping AFAIK most here are drag and hand soldering their SMD stuff, me too.QuoteLead has been used by humans with little care for millennia, for the little that you might contribute, burn it or bury them, just like you do with projectiles.QuoteLook, the stuff has a place but if it's of the lead free muck type....in production. No need to make hobbyist projects any trickier than necessary. If you've not had eperience with paste before, clean application only on the pads is preferable if you want a tidy job.....not one that you have to chase the little solder balls that are between pins.There's been mention of a good one from Loctite in the forum, a search will find it and there's some product #'s for it too. Just be sure to use the Search button here, not the useless search box.

author: mjkuwp
author_rank: Unknown
timestamp: November 12, 2016, 01:35:05 pm
content: This is where I got my syringe paste and plunger from. They have economy ones but I got the nice one. I think it is best to get the good plunger because you need fine control.http://www.zeph.com/plungers.htmI just looked at the needle and it is red so I guess I have the 24 Gauge one. I bought it several years ago so... I don't have a record of what it is.The paste in a syringe is only good for rework or relatively sloppy one-off soldering imo. For best paste results you should use paste from a jar - from Digikey and stencils from ohararp.com or oshstencils.com

author: Wolfie
author_rank: Contributor
timestamp: November 12, 2016, 11:52:41 pm
content: Ya, I just found out about the stencils from oshstencils. I hadn't considered stencils before. As I said, very new at this. I thought that SMD folks used paste most of the time. The only SMD work I have done was assembling some WiFi modules used for christmas lighting and had a bugger of a time with them. I was using an old and cheap soldering station thats not very temp controlled. It has a knob but no sort of digital control that I can tell.Since then I purchased a cheap chinese (Yihua) rework station with both air and an iron. So far I am liking it way better.This solder paste is not lead free, its 62/36/2 silver bearing.Re zeph.com, yea, I had found them through google. I just thought $30 for a plunger seemed excessive. Figured I could print one for about 10c worth of ABS filament.Yall think it might be better to re-dispense this into a .5cc or other small syringe rather than try to use direct?