good solder paste and flux pen - Page 1
Forum section: electronics / beginners

author: WhiteFireDragon
author_rank: Regular Contributor
timestamp: October 26, 2012, 04:04:18 am
content: I need some recommendations on which solder paste and flux to purchase because I'm a bit overwhelmed with the selections. If I need a syringe and needle to apply the paste, then recommendation on that would be nice also (I have no idea what size to select). I did some searches, and here's what I've came up with. Please let me know if this is a bad selection or if there are better choices:MCN-300 Soldering Solder Paste 63/37Kester 951 flux pen1cc Leur Lock syringe25gauge dispense needleEDIT:I ended up going with this "Fusion"MBC-360-880 (60/40)from SRA for only $4, but I realized after reading the package, it's for brazing and soldering machines. Can I use this for SMD hot air rework? Then I noticed SRA hasseparate paste for electronics. What distinguishes brazing paste from electronics paste if they're both lead-based types? Electronics paste is 3 times the cost of this fusion brazing paste. Can I use this cheaper brazing paste for electronics, or is this whole tube a waste?

author: Colfaxmingo
author_rank: Contributor
timestamp: October 26, 2012, 09:05:38 pm
content: Are you using a stencil or applying paste free hand?Unless you are doing a batch of boards and have a stencil made, use a syringe. Loading a syringe with paste from a tub is a mess.I would recommend buying the paste already in the syringe, I've had some good stuff from Kester but your mileage may vary.Most syringes I have seen are made to go into dispensing machines. I like using a plunger style hand syringe instead.http://www.zeph.com/plungers.htmAs far as needles, 22 gauge is pretty good except for really, really tiny stuff. Too small and its hard to control the paste flow.Flux pens all suck. They are better than nothing but they are just not that great in my opinion.tl;drKester Paste 63/37 syringeskip the penzeph hand plunger22 gauge /18 gauge tips

author: Spikee
author_rank: Frequent Contributor
timestamp: October 26, 2012, 10:14:11 pm
content: A few days ago i had the same problem as you. But after alot of research i know what is the best (for me) .Solder paste: Lodestar 50gr :http://www.ebay.com/itm/50G-Soldering-Repair-Solder-Paste-Cream-Welding-Paste-/160904412705?pt=LH_DefaultDomain_0&hash=item2576a67e21Water soluble flux (have to clean with warm water / distilled (demineralized) water : i got Chip Quik SMD4300TF10CC syringe : somewhere on ebay / amazonPinheads:http://www.ebay.com/itm/370459994458

author: ptricks
author_rank: Frequent Contributor
timestamp: October 26, 2012, 11:21:25 pm
content: Not a fan of the kester flux pen. I was using it one day and suddenly a whole bunch of flux came out, then the whole pen dumped its contents onto the work surface. Apparently they don't glue the end with the tip onto the marker, it is just a press fit.Be careful where you buy paste solder , it has a very short shelf life and you can easily end up with something that doesn't work well at all.If it is cheap, it is cheap for a reason , and it isn't because they want to save you moneyI like SRA for my soldering products, they go through stock quick so what you get is new, all the stuff has lot and expiration dates clearly printed.http://sra-solder.com/section.php/10/1/soft_solder_paste

author: T4P
author_rank: Super Contributor
timestamp: October 27, 2012, 05:18:51 pm
content: The lodestar ones are not particularly cheap, they are just lower mass. they will perfectly well on the 3buck one i bought from DX but 1buck with S&H sounds suspiciousOH, STAY AWAY FROM WATER SOLUBLE FLUX PLEASE!!! Unless you want to clean it immediately all the time after soldering, go ahead.And don't clean using deionized water or any distilled water, it will ascerbate the problems of water soluble flux, use IPAUse NoClean flux or RMA flux (NoClean is better, i don't know what it's made of but it smells a little pleasant, i like rosin's smell too but getting close to it can give you inflamed eyes. Great if you want to walk out of your lab sometimes with a swollen eye and meeting somebody at the door and well scaring the heck out of them)And don't forget another thing on two, NoClean flux is not really no clean all the time. You can get some residue but it doesn't really matter, although cleaning them off is easier

author: Amarbir[Lynx-India]
author_rank: Frequent Contributor
timestamp: October 27, 2012, 07:03:31 pm
content: Well,Kester 951 Soldering Flux "Piece of Garbage " .Ordered 5 Units To My USA Office ,Once I Carted the material from there i find just like my friends up said all flux had leaked .My idea was to use 1 unit and sell 4 lol .In my case 1 was totally empty and 4 were partial filled lol .the flux itself is also not that great my idea was to use it on the ic and smd that i rework when i do data recovery .But alas is a garbage pile . Flux Paste should be better there are so many types .

author: nanofrog
author_rank: Super Contributor
timestamp: October 27, 2012, 07:39:59 pm
content: Quote from: Amarbir[Lynx-India] on October 27, 2012, 07:03:31 pmPerhaps you recieved fake goods.Where did you source it from?

author: Amarbir[Lynx-India]
author_rank: Frequent Contributor
timestamp: October 27, 2012, 08:07:39 pm
content: Quotehttp://www.ebay.in/itm/200775672716?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

author: mariush
author_rank: Super Contributor
timestamp: October 27, 2012, 09:07:19 pm
content: Hahahaha .... and you're surprised they were shit?These kind of pastes have to be kept relatively cool and sealed.. who knows how long this guy had them in stock and how well they were shipped to you from US.You might revive the paste with a few ml of isopropyl alcohol, mixing it well with the paste you still have.What's wrong with farnell/element14/newark or digikey, don't they send to India? Shipping fees too much?

author: nanofrog
author_rank: Super Contributor
timestamp: October 28, 2012, 01:05:32 am
content: Quote from: Amarbir[Lynx-India] on October 27, 2012, 08:07:39 pmI'd stay away from eBay or similar sites for Kester products, as this definitely isn't the first time there's been an issue from there (fake, past the expiration date, got too hot). Far better to get it from an authorized distributor IMHO. Bit more expensive, but as the old saying goes, you get what you pay for.

author: ablacon64
author_rank: Frequent Contributor
timestamp: October 28, 2012, 01:10:22 am
content: Quote from: Amarbir[Lynx-India] on October 27, 2012, 08:07:39 pmCan't see the link, it's blocked for my country. That is strange, Kester 951 has been very recommended in another topic.

author: T4P
author_rank: Super Contributor
timestamp: October 28, 2012, 04:46:34 am
content: He got a fake. It's a great flux pen

author: andete
author_rank: Contributor
timestamp: October 28, 2012, 05:15:33 am
content: I use this lead free solder paste in syringe from farnell:http://be.farnell.com/edsyn/cr-88/solder-paste-lead-free-5ml-10g/dp/1521898and this flux pen from RS:https://be02.rs-online.com/web/p/flux-cored-solder/2513637/Both do the job just fine.

author: T4P
author_rank: Super Contributor
timestamp: October 28, 2012, 06:00:40 am
content: That edsyn solder paste is really pricey and hell forbid it, LEAD FREE WTF!Just like their products. Not even digital loop in a few hundred dollar station!

author: Amarbir[Lynx-India]
author_rank: Frequent Contributor
timestamp: October 28, 2012, 06:13:59 am
content: Quote from: T4P on October 28, 2012, 04:46:34 amWell,i do not think so ,the seller is from US of A .The Store Is ->http://stores.ebay.com/tgsolar

author: ptricks
author_rank: Frequent Contributor
timestamp: October 28, 2012, 04:56:31 pm
content: Quote from: T4P on October 28, 2012, 04:46:34 amIt would be fine if they didn't come apart. Mine wasn't fake, I bought it from Mouser.I switched to using these, they are refillable.http://sra-solder.com/product.php/7040/141/sra_312_no_clean_flux_pen_refillable

author: free_electron
author_rank: Super Contributor
timestamp: October 29, 2012, 10:08:19 pm
content: Never had trouble with the kester pens. We run through 5 or 6 a month and buy them in 12-packs. I believe from Techni-tool or Mouser.951 is a very good flux. We either use that, or the 2231 water soluble.Are you sure you are handling them right ? they need to be kept laying flat at all times. DO NOT KEEP THEM UPRIGHT ONCE YOU START USING THEM !The pen comes out of the factory with a dry tip ( no flux on it ) you need to pump the pen to prime the tip and get the flux going.if you keep the pen upright once primed the flux will settle in the pump mechanism and it will jam the mechanism. result :leaking (stuck open) or no flux comes out (stuck closed)Laying the pen flat keeps the mechanism 'wet' and prevets it jamming up.note that these flues are NOT for reflow. for that you need a tacky or gel flux. the alcohol based pens are for manual rework only.one thing we do frequently is , after all parts have been soldered by hand : go quickly over the board with the 951 or 2231 pen so it is nicely wetted with flux and then go over it with the Leister ( hot air gun) . this re-melts all solder , the flux does its work and all the parts nicely auto align. you cannot tell the difference between a board made like that and a machine made.oh, and NEVER EVER mix flux types ! don;t use water soluble flux with rosin core solder and vice versa. you are asking for trouble. Not only is it a mess to clean up , the fluxes react with each other as well.

author: WhiteFireDragon
author_rank: Regular Contributor
timestamp: November 09, 2012, 12:55:53 am
content: Quote from: ptricks on October 26, 2012, 11:21:25 pmThanks for the link, I bought some from SRA and received it already. I ended up going with this "Fusion"MBC-360-880 (60/40)from SRA for only $4, but I realized after reading the package, it's for brazing and soldering machines. Can I use this for SMD hot air rework? Then I noticed SRA hasseparate paste for electronics. What distinguishes brazing paste from electronics paste if they're both lead-based types? Electronics paste is 3 times the cost of this fusion brazing paste. Can I use this cheaper brazing paste for electronics, or is this whole tube a waste?I also got this#312 No-Clean flux penfrom SRA. I'll put this post in the OP.

author: nanofrog
author_rank: Super Contributor
timestamp: November 09, 2012, 05:46:47 pm
content: Quote from: WhiteFireDragon on November 09, 2012, 12:55:53 amFirst two links are the same link (MBC-360-880). Quick look states it's using Rosin as the flux material, so it will work with electronics.BTW, didn't see anything on mesh/particulate size, and even if that's good, the flux may not be that great. That said, at $4.00 it's not worth sending it back IMHO, so go ahead and experiment with it and see how it goes.

author: ptricks
author_rank: Frequent Contributor
timestamp: November 12, 2012, 10:20:40 pm
content: I think the paste bought will work fine. If you have questions be sure to ask them , I have used them for quite some time now and they seem knowledgeable about what they sell,. Not many electronics places you can call and ask about the solder and get a good reply, most places just tell you something like 'its solder, says for electronics"The paste they use are manufactured by fusion inc.http://www.fusion-inc.com/

author: bitwelder
author_rank: Super Contributor
timestamp: January 01, 2013, 11:34:22 am
content: I attach my questions to this old thread, as anyway they are related: how long does flux pens/bottles last before they expire, and what's best way to keep them stored? Is the usual 'cool and dark' place ok or would it be better a colder place (let's say, a fridge not used for foodstuff)?And finally: what about the flux in the solder wick, does it has same shelf life as the liquid flux?

author: cwalex
author_rank: Frequent Contributor
timestamp: January 02, 2013, 01:55:21 pm
content: Quote from: Amarbir[Lynx-India] on October 28, 2012, 06:13:59 amThe liquid flux inside may be authentic but the pens look like all the other cheap pens I've seen on ebay. That is probably the problem you had with the leakage.

author: katjap
author_rank: Newbie
timestamp: January 03, 2013, 08:12:52 am
content: I bought a syringe of Kester 256 off ebay. It was the first tube of solder paste i'd ever bought. I stuck it right in the fridge and then a few days later my pcb was ready and i let it sit out to warm up for a few hours. I struggled to squeeze the play-doh'y stuff out the end of it.It was the first time i'd used it so i thought all paste was like that. I don't think i'll ever buy solder paste off ebay again.

author: marshallh
author_rank: Unknown
timestamp: January 03, 2013, 08:25:25 am
content: Stay away from water soluble or no-clean fluxes.Here's the work of Kester water soluble: (bought legit from sparkfun a long time ago)Keep in mind this happened in about 1 week. I had cleaned with distilled water. No matter, my plated vias were completely toast. This is just one particular example from quite a while ago.I have lost hundreds of dollars in incidents related to this flux. You can wash it all you want, you will never get it *all* off, and 3 months down the road, you will have nice low-ohm shorts between your fine pitch QFPs with a few heat cycles.Now I only use regular rosin flux.. MG Chemicals makes a good rosin flux pen, it is not going to eat your lunch like the previous one.http://www.mouser.com/ProductDetail/MG-Chemicals/835-P/?qs=sGAEpiMZZMvcAs5GUBtMdQwLF%252bU3Jn6E

author: Unknown
author_rank: Unknown
timestamp: January 03, 2013, 12:02:10 pm
content: Water soluble is known to be corrosive, so the boards have to be washed throughly immediately after assembly. No-clean fluxes are very different: they are safe and can be left on the boards without damaging traces or creating shorts. The only reason to clean the boards is very high impedance circuits, some harsh environmental conditions and looks.

author: kanurys
author_rank: Contributor
timestamp: January 25, 2014, 10:16:50 pm
content: To continue this discussion...Solder Paste: I'm also interested in learning about what type of solder paste to use and not starting a new thread on this topic. Can members suggest a list of desirable paste compositions as well as brands/part numbers?It looks like this is pretty middle of the road stuff:http://sra-solder.com/product.php?xProd=6063WC-360-830 SOLDER PASTETin/Lead: 60/40Flux: IntermediateCharacteristics: Restrictive - What does this mean?As for flux: I've had good luck with a Chemtronics CW8100 No Clean Flux Dispensing Pen. That's a quality company and it's worked well over aged applications for me.

author: kanurys
author_rank: Contributor
timestamp: February 08, 2014, 05:02:04 am
content: Quote from: kanurys on January 25, 2014, 10:16:50 pmIt turns out that the stuff I quoted, above, is not electronics grade paste. SRA told me that for electronics they sell and recommend Chip Quik.