Flux - Page 1
Forum section: electronics / beginners

author: fixit7
author_rank: Regular Contributor
timestamp: June 11, 2019, 09:53:10 pm
content: I am researching flux. I see there are lead free, acid based, and no clean up ones.Which is best for circuit boards?I know every situation will be different.I returned some 12 gauge wire to an auto repair store because the copper strands were brittle and blackish gray.

author: Vtile
author_rank: Super Contributor
timestamp: June 11, 2019, 10:29:31 pm
content: As starting hobbyist I would say that go with Rosin activated types if you need extra flux.I'm heretic and have even some random Stannol brand copper pipe flux which is considered as big no for electronics, but I use it only for bigger electromechanical soldering jobs ... read: heavy old connectors ie. corroted battery clips and those stained old wires.99% of times my rosin core lead-tin alloy soldering wire is enough.

author: MarkF
author_rank: Super Contributor
timestamp: June 12, 2019, 12:21:26 am
content: NEVER use acid based flux for anything electric.Acid based flux is for plumbing.

author: perieanuo
author_rank: Frequent Contributor
timestamp: June 12, 2019, 05:48:35 am
content: Quote from: MarkF on June 12, 2019, 12:21:26 amThis can be discussed.you can use ANY flux type then clean the pcb, what about this approach?Acid does clean very good.I use rosin like everybody but for smd you have other options.So for me the answer is the fluxes that cleans best and doesn't boil easy forming bubbles and moving your smd around.usually some american types those in tubes like rma 223 .rosin is for through hole components.For pro smd work, you usually buy liquid ones but those are sold in 5-10 kg minimum quantities , I had one for testing for video chip changing in laptops rework.It was the best I used, liquid like water,I have to search for the code if necessary only.So if you want to economise some money go rosin and eventually dilute this nd add some after shave for good smell, if you want some quality in rework go rma223 and his cousins.acid or basic, doesn't matter, you clean the board after.Regards,pierreEnvoyé de mon iPad en utilisant Tapatalk

author: MarkF
author_rank: Super Contributor
timestamp: June 12, 2019, 07:49:19 am
content: Nothing to discuss.There are very aggressive rosin fluxes available if need be.NEVER USE ACID FLUXES ON ELECTRONICS.

author: Ian.M
author_rank: Super Contributor
timestamp: June 12, 2019, 08:55:33 am
content: If you *could* clean the board well enough acid flux would be tolerable, but you cant guarantee to get all traces of it out from under components and where its wicked up under wire insulation, or between wire strands and it only takes a small trace to wreck your board as its residue + atmospheric moisture & CO2 aggressively corrodes copper. The CO2 forms copper carbonate from the corrosion residue, freeing the original acid traces left by the flux to carry on corroding more copper.

author: Zero999
author_rank: Super Contributor
timestamp: June 12, 2019, 10:23:18 am
content: I understand why acid flux can be a problem, but why is it suitable for plumbing? How are the corrosion problems avoided when joining two pieces of copper piper together, yet are a problem on a PCB?Also note that lead free solder is not suitable for hobbyist usage. It's actually more dangerous, than leaded solder, because it requires a higher temperature iron and a more aggressive flux which is irritating to the lungs. Although lead is toxic, providing sensible precautions are taken, such as hand washing after use, the amount adsorbed into the body is well below the level which can cause adverse effects.Lead free solder was introduced because people often don't dispose of their old electronic equipment responsibly, resulting in lead leaching out into the environment and polluting the groundwater. It has nothing to do with health and safety.

author: No.Mad
author_rank: Regular Contributor
timestamp: June 12, 2019, 04:19:22 pm
content: Quote from: fixit7 on June 11, 2019, 09:53:10 pmI covered major types of fluxes with some pros and cons in this thread:https://www.eevblog.com/forum/repair/pcb-cleaning-methods-solvents-and-techniques/msg2478840/#msg2478840If you need more info, ask right away what specifically you are interested in. Asking which is best for PCB is somewhat wrong, cause you choose your solder, flux and cleaning solvent depending on work you do.Regards

author: Ian.M
author_rank: Super Contributor
timestamp: June 12, 2019, 04:39:11 pm
content: Quote from: Zero999 on June 12, 2019, 10:23:18 am15mm copper pipe has a wall thickness of 0.7mm. A 1oz copper PCB has traces 20 times thinner. Assuming pitting corrosion can cause a pipe leak after 50 years, then corrosion at the same rate can eat through a PCB trace in only 2.5 years. Also the grease component of acid plumbing flux is seldom solvent washed off the plumbing joint, so the grease residue partially protects the copper surface.The *WORST* thing you can do to a PCB contaminated by acid flux is only wash it with a non-polar solvent as that removes nearly all the resin and/or grease and leaves all the adhered acid metal salts behind.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: June 12, 2019, 04:41:50 pm
content: https://uk.rs-online.com/web/p/products/3217289/?grossPrice=Y&cm_mmc=UK-PLA-DS3A-_-google-_-CSS_UK_EN_Tools-_-Soldering_And_Desoldering_Tools%7CSolder_Flux_Removers_And_Cleaners-_-PRODUCT_GROUP&matchtype=&pla-393922589193&gclid=EAIaIQobChMIhtykkrHk4gIVoQvTCh3avgdxEAQYASABEgKiMPD_BwE&gclsrc=aw.ds

author: perieanuo
author_rank: Frequent Contributor
timestamp: June 13, 2019, 08:38:23 am
content: I must reply to acid haters:from wikipedia:QuoteI used colophane for years, it's basically acid, works without damage to pcb.ALL is in quality of work done, I must repeat, cleaning is a essential part after soldering.I saw basic fluxes that damage the boards, like those intended for copper plumbing.So for beginner use colophane flux or RMA223 or cousins.Cost is ok.What other people discuss for pro soldering is another matter.If the person asks, obviously it's not a pro, so let's discuss cheap fluxes.I can do me also a big article about pro's flux, who cares.But don't repeat like a monkey acid is bad.Maybe it's not the best.regards,Pierre

author: tooki
author_rank: Super Contributor
timestamp: June 13, 2019, 09:31:41 am
content: Quote from: Zero999 on June 12, 2019, 10:23:18 amWell, regardless of your opinions on the matter, since March 2018, leaded solder may no longer be sold to consumers in the EU (and other countries that follow the EU's rules, like Switzerland; the rule in question is REACH Annex XVII). Hobbyists here in Europe will have to work with lead-free, like it or not. Honestly, though it's not as easy as leaded, it's still fine, especially if you buy a more expensive alloy like SAC305, and not the cheap 99.7-100% tin kind. It's true that the flux fumes are a bit worse, but it's not as though the fumes from classic rosin flux are somehow good for us, either!Quote from: Zero999 on June 12, 2019, 10:23:18 amWell, RoHS was conceived back when CRT TVs contained several kilos of heavily leaded glass. But ultimately, it was a dumb policy enacted by do-gooder politicians without enough technical knowledge to understand the consequences.

author: tooki
author_rank: Super Contributor
timestamp: June 13, 2019, 09:41:34 am
content: Quote from: perieanuo on June 13, 2019, 08:38:23 amFYI, "colophane" is called "rosin" in English. (We also have the archaic word "colophony" for it, but this isn't used by native speakers any more.)Anyhow, while rosin does indeed consist of resin acids, it'snotan "acid flux" as such. The abietic acid in rosin isnotactive as an acid in any meaningful sense. It's only activated when hot, which is why it works so well as a flux. At room temperature it's so neutral that it can be used toprotectcopper from corrosion.I cannot state emphatically enough how irresponsible it is to say that acid plumbing flux is in any way acceptable for hobbyist electronics use. It's not. Even the acid fluxes made specifically for electronics (the "water soluble" fluxes) can only be used in VERY strictly controlled applications with strict cleaning processes, and are categorically unsuited for hobbyist use.

author: tooki
author_rank: Super Contributor
timestamp: June 13, 2019, 10:17:14 am
content: Quote from: fixit7 on June 11, 2019, 09:53:10 pmBasically, fluxes fall into a few categories (in terms of active ingredient, not the delivery method):1. Rosin2. No clean3. Alcohol4. Acid (water soluble)First off, acid/water soluble fluxes are categorically unsuited to hobby electronics. Do not even think about using them. (Any flux that says it uses ammonium chloride or zinc chloride is an acid flux and must not be used.)Rosin fluxesare made from the refined sap of pine trees, with activators added to improve the fluxing action. You can get rosin fluxes with varying concentrations of rosin and activators, making them more or less aggressive, and more or less hazardous. (Halogen activators are more effective, but bad for the lungs.)Highly activated fluxes, which are better for hard-to-solder things like old components, are labeled as RA, ROM1 (halogenated), or ROM0 (halogen free). The flux in my favorite solder, Kester 44, is RA.Slightly milder rosin fluxes are classified RMA, ROL1, and ROL0.No-clean fluxesare essentially a subtype of rosin fluxes, made from either extra-refined rosin, or even from synthetic rosin (sometimes labeled as resin instead), such that the flux residues are clear and look better. They also may contain much less of the active ingredients, especially in liquid and gel fluxes. They aren't usually as active as rosin fluxes. They may be classified RMA (rarely), ROL1, ROL0, REL1, or REL0. (Other classifications exist, I just listed what you're likely to see.)- Both rosin and no-clean fluxes exist as rosin core solder, paste and gel, and liquid flux forms. Note that despite the name, you can clean off no-clean flux, and that despite not saying so, rosin flux residue doesnotneed to be cleaned for most applications. For the kind of stuff you're doing, it's purely a matter of aesthetics.Alcohol fluxesare used in some gel fluxes and in solder paste.Lead-free fluxesare simply fluxes formulated to tolerate the higher temperatures of lead-free soldering. (Regular fluxes may degrade at those temperatures before having a chance to work.)In a nutshell, here's what I recommend:1. If you can, use rosin-core leaded solder as your everyday solder. It's the easiest to work with. (For example, my favorite solder, the Kester 24-6337-00xx series, which is 63/37 leaded alloy with 44 (RA) flux. I recommend either 0.031" or0.020" size.)2. A tacky gel or paste flux. I use the MG Chemicals8341 No-Clean Flux Paste. This is really good for heavily corroded surfaces, or for SMD components, where the tacky texture helps hold components in place. (MG also makes the 8342 RA flux paste, which should be even more aggressive, I just haven't had the chance to try it.)3. A liquid flux pen. The low solids content makes these not as effective as the paste, but it's easier to clean up, and works well for when you need to flux something that isn't heavily corroded. I use this often for tinning clean wire, for component legs and pads on through-hole soldering, etc. I'd suggest an MG Chemicals 835-P,Kester 186, orSRA 312.

author: Zero999
author_rank: Super Contributor
timestamp: June 13, 2019, 02:30:52 pm
content: Quote from: tooki on June 13, 2019, 09:31:41 amI doubt that will make much difference. I expect hobbyists will still have no problem getting leaded solder years to come. A quick search reveals it's widely available on-line and I doubt many places will check whether the buyer an individual or a business.

author: MarkF
author_rank: Super Contributor
timestamp: June 27, 2019, 08:27:36 pm
content: I just saw a new video relevant to this discussion:

author: fixit7
author_rank: Regular Contributor
timestamp: June 27, 2019, 11:47:01 pm
content: I have read thru the discussion.All those pens are kinda expensive for the quantity.What about a liquid flux?Surely, some of them are ok.I do not mind brushing it on.

author: sdt
author_rank: Newbie
timestamp: June 28, 2019, 05:56:13 am
content: Those syringe-style packs in the video look as though they need some kind of external plunger mechanism.Is there some hand-operated device you put those into? I haven't been able to find anything that looks suitable.

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: June 28, 2019, 06:45:59 am
content: AFAIK those Syringe Packs are used with a compressed air dosing unit. I have on of those at home, you connect it to your shop compressor, adjust the tim you want that thing to "push" on the plunger, connect a hose with a plunger to the syringe and activate it using a foot pedal to apply an exact amount of whatever is in the syringe onto whatever that stuff is supposed to cover.I got lucky to pick my device up from a closing of a hospital, but I have no idea where you could get such a thing, neither do I know how this device is actually called, I just know they exist and are pretty usefull for deploying solder paste.

author: sleemanj
author_rank: Super Contributor
timestamp: June 28, 2019, 09:24:23 am
content: The syringes are dispensing syringes same as for solder paste dispensing. If you have compressed air available, then glue dispenser is the the keyword for aliexpress they hook up to your compressed air source and provide the appropriate foot switch, timer, pressure adjustment and venturi pullback suction etc, typically about 70-80 USD.If you don't have compressed air available or don't want to spend that sort of money then there are various ways, but for flux the simplest way is probably the best, go get a 10CC syringe from your local chemist, and a plastic dispensing tip for it they come in various sizes, you can usually suck the flux out of the dispensing syringe into the normal syringe just like you would drawing up a medicine, or if it's a bit thick for that just pull out the plunger from the normal syringe and use a pokey thing to push the stopper on the dispensing syringe and squirt the goodness out into the normal one.

author: djnz
author_rank: Regular Contributor
timestamp: June 28, 2019, 09:40:13 am
content: For general hobby use, I like RMA fluxes, but hobby use is an application where it almost doesn't matter. For more serious use, there is no one answer. You need to consider the temperatures the product will see, and the product life you are targeting.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: June 29, 2019, 03:52:08 am
content: The "no clean" stuff can be a real bastard to clean. It makes your boards look dull if you cannot get it off.Also, I sent several days one time trying to figure out why my SPI programming header was so flaky. It has a thin coat of flux on it.

author: tooki
author_rank: Super Contributor
timestamp: June 29, 2019, 09:32:45 am
content: Quote from: MarkF on June 27, 2019, 08:27:36 pmYikes. The Weller flux there says “zinc chloride” right on the tub, meaning it’s an acid flux totally unsuited for electronics. That makes me wonder whether any of the other ones in tubs (that don’t expressly say “rosin” or “for BGA”) are acid fluxes.Moreover, while that video does show how easy the fluxes are to apply (or not), soldering all-new components onto new ENIG PCB is a very easy task. A much more illuminating comparison would be with old, tarnished parts.

author: tooki
author_rank: Super Contributor
timestamp: June 29, 2019, 09:38:24 am
content: Quote from: fixit7 on June 27, 2019, 11:47:01 pmYes, on a per-milliliter basis the pens are expensive, but about half the cost is the pen itself, not the contents. You can refill flux pens, so as long as the nib is still in decent shape, you can use the pen for a LONG time. (You can also go to an art supply store and buy replacement nibs, they sell them for certain kinds of graffiti markers.) But also, don’t underestimate how frugal flux pens are — they let you apply flux just where you need it, so you waste very little.As for liquid vs. paste: I go into this extensively in my earlier reply, and why you want both. (In other words, of course some are fine, I listed three... you can buy those fluxes in non-pen form if you want.)

author: fixit7
author_rank: Regular Contributor
timestamp: June 29, 2019, 10:46:17 pm
content: Much thanks for the video. I think he showed the better ones first.I found a 150 g for $13.15. Do not mind waiting a month for it.NT ZJ-18 150g Yellow paste Advance Quality Solder Flux Soldering Paste High

author: MarkF
author_rank: Super Contributor
timestamp: June 30, 2019, 12:20:53 pm
content: I am a little confused about the NT ZJ-18 Yellow paste.I saw several different sizes of ZJ-18 on Amazon.However, they were a darker yellow in the pictures.Making me think they contained a lot of rosin.Are all NT ZJ-18 fluxes created equal?(Amazon just because I have other things I want.)

author: fixit7
author_rank: Regular Contributor
timestamp: July 01, 2019, 02:19:37 am
content: I noticed that too.I try to go with whatever has the highest rating, even though many items have no ratings.Then I look at the sellers ratings next.