Which solder fluxes must *absolutely* be cleaned?

[Matir]

Which solder fluxes must *absolutely* be cleaned? Most of the datasheets for the wire solder (I suppose paste is different, as are add-on fluxes) I have seen indicate cleaning is not generally required.  This includes MG chemicals RA (4884 series), Multicore 502, Kester 44, etc.  On digikey, looking at 63/37, 64/40, and SAC305 I have yet to find a datasheet that says "if you don't clean this flux, here be demons!"

[helius]

Water-soluble ("organic") fluxes, and those with added halides over a very small level, must be cleaned. This includes some RA fluxes if the chemistry leaves active halides in contact with the board. Certain fluxes that contain phosphates must also be cleaned: these are normally found in "tip tinner" products rather than solder wire.
63/37, 60/40, and SAC305 are alloys. They do not specify the flux type.

[Matir]

Yeah, I should've just clarified that I was mentioning the alloys to indicate I was looking at a variety of different products.

So for prototypes/one-offs, it seems that most solders are fine without special cleaning.

[mariush]

I have yet to find a datasheet that says "if you don't clean this flux, here be demons!"

97SC HYDRO-X 2% .064DIA/16SWG    Lead Free Water Soluble Wire Solder Sn96.5Ag3.0Cu0.5 (96.5/3/0.5) 14 AWG, 16 SWG Spool, 454g (1 lb)
https://www.digikey.com/product-detail/en/multicore/732977/82-135-ND/2498933

Stranded wire should not be used. Strip any insulation back so that flux residues are not trapped during the washing process.
CLEANING
It is essential that the residues from soldering with Multicore Hydro-X cored solder wires be removed as soon as possible after soldering.
The residues from Multicore Hydro-X cored solder wires may be readily cleaned in conventional equipment using water. It is important that the
cleanliness of boards and components is thoroughly checked after soldering and cleaning. The usual procedure is to continuously check the co
nductivity of the final rinse water as a measure of ionic contamination. Samples of cleaned boards should be subjected to a laboratory corrosion test, insulation
resistance test, or ionic contamination assessment.

should be enough warnings and precautions for you.

[P90]

Solder labels should replace the phrase "water soluble" with "death," since too many novices seem to think it's water related so it must be safe...  LOL

[Mechatrommer]

Solder labels should replace the phrase "water soluble" with "death," since too many novices seem to think it's water related so it must be safe...  LOL

maybe its just you. most of easily accessible poison on earth are water soluble.

btw, i commonly use ZnCl3 flux (besides the Zephflux no clean flux from Zephyrtronics).. because its the easiest flux i have here. at one point i bought a no clean flux from china its just look like water, but its a crap i let it vaporized to air for good on purpose. ZnCl3 is a bit conductive, it must be cleaned. yeah i know ZnCl3 is for plumber flux, one hundred people have advised me on that, but until i find the easier to use flux, i stick with ZnCl3 for general purpose. i use Zephflux for difficult to clean or small pitch chip only since Zephflux is rare earth element around here (difficult to order). afaicr i dont have problem with Zephflux if i leave it on the pcb. but usually i clean them all so my board will looks neater.

[Matir]

I have yet to find a datasheet that says "if you don't clean this flux, here be demons!"

97SC HYDRO-X 2% .064DIA/16SWG    Lead Free Water Soluble Wire Solder Sn96.5Ag3.0Cu0.5 (96.5/3/0.5) 14 AWG, 16 SWG Spool, 454g (1 lb)
https://www.digikey.com/product-detail/en/multicore/732977/82-135-ND/2498933

Stranded wire should not be used. Strip any insulation back so that flux residues are not trapped during the washing process.
CLEANING
It is essential that the residues from soldering with Multicore Hydro-X cored solder wires be removed as soon as possible after soldering.
The residues from Multicore Hydro-X cored solder wires may be readily cleaned in conventional equipment using water. It is important that the
cleanliness of boards and components is thoroughly checked after soldering and cleaning. The usual procedure is to continuously check the co
nductivity of the final rinse water as a measure of ionic contamination. Samples of cleaned boards should be subjected to a laboratory corrosion test, insulation
resistance test, or ionic contamination assessment.

should be enough warnings and precautions for you.

Yup, that's a good warning

[wraper]

ZnCl3 is a bit conductive, it must be cleaned. yeah i know ZnCl3 is for plumber flux, one hundred people have advised me on that, but until i find the easier to use flux, i stick with ZnCl3 for general purpose. i use Zephflux for difficult to clean or small pitch chip only since Zephflux is rare earth element around here (difficult to order). afaicr i dont have problem with Zephflux if i leave it on the pcb. but usually i clean them all so my board will looks neater.

Please tell how you clean it. Because unless you ultrasonic it like hell, that crap will be left on the board regardless how hard you rub it with a brush, wadding or whatever. And especially in the holes.

because its the easiest flux i have here.

Like if you are living in North Korea. Also I guess you should hate your soldering iron tips and your lungs.

[Mechatrommer]

with thinner/alcohol, brush and tissue, lots of them if necessary. yeah i do agree the "neck" my older soldering tip is in bad shape. in xchange to easy soldering. the new tip is waiting for operation. i dont use excessive amount usually i just dip the soldering tip into it, just a small area to the tip. except for really big area that needs big heat.

[wraper]

i dont use excessive amount usually i just dip the soldering tip into it, just a small area to the tip. except for really big area that needs big heat.

Whoa? You dip the tip into the flux? 

[P90]

[Mechatrommer]

damned didnt i mention 100 people have adviced me on this? btw. my 1st hakko tip is gone, the tip was totally disintegrated from the main body... now i used $5 iron, modded with the hakko heater inside, the tip? well, attached pictures is worth a 1000 words, hilarious as it is, i dont mind it so long it works a treat. hakko heat element is a tank for many years now... i have my 2nd hakko bought rarely used still looks like new, but its for standby part in case i need soldering in emergency... next time i buy new $5 iron and put the 1st hakko heater inside again. no worry i'm yet to see any serious corrosiveness on my pcb and components, so i guess i'll stick with it. about the lung, i blow them away the flux fumes, i dont inhale smoke other than tobacco's... tobacco is several 1000s more dangerous imho.

For all the good things ZnC12 has done for the world, and ZnC12 fluxes have done for radiator repair, the hazards seem relatively minor and are easily dealt with. Shop exhaust, personal protective equipment and good personal hygiene will go a long way to keeping the zinc chloride on the work piece, off the shop floor, and out of your hair, lungs and skin

from http://www.johnsonmfg.com/temp/HWhtml/ZCFS3p~1.htm ...

[wraper]

LOL

[wraper]

damned didnt i mention 100 people have adviced me on this?

Sure they were idiots who don't understand anything in how soldering should be done  .

[P90]

you've been sniffing too much flux fumes...    LOL

[KL27x]

Please tell how you clean it. Because unless you ultrasonic it like hell, that crap will be left on the board regardless how hard you rub it with a brush, wadding or whatever. And especially in the holes.

IME, you can sufficiently wash this flux off of copper/tin with hot water and a brush. It's ferrous metals where this embeds and promotes corrosion... like no matter what. It is used to solder copper pipe, and the joints don't corrode.

The only way I have found to stop zinc chloride from corroding ferrous metal in the long run is to physically remove it by abrasion or by etching the metal with a different acid to remove the contamination. Phosphoric or acetic acid work. At one point I used plumbers flux for soldering to stubborn (iron) battery terminals... years later, not such a good idea, afterall. But all my copper/tin circuit boards fluxed with same are fine.

[wraper]

IME, you can sufficiently wash this flux off of copper/tin with hot water and a brush. It's ferrous metals where this embeds and promotes corrosion... like no matter what. It is used to solder copper pipe, and the joints don't corrode.

IIRC it also embeds (and stays conductive) into FR-4 in the areas without solder mask. You won't see it with cheap multimeter on manually cleaned board, but if it can measure to something like 50 M , then likely you will be able to measure it. Not to say there is zero chance to clean it from under any SMD.

[Mechatrommer]

IIRC it also embeds (and stays conductive) into FR-4 in the areas without solder mask. You won't see it with cheap multimeter on manually cleaned board, but if it can measure to something like 50 M , then likely you will be able to measure it. Not to say there is zero chance to clean it from under any SMD.

confirmed. i usually measured 1-10 Mohm of conductivity betwen nodes/traces. well my circuit usually a one-off and not sensitive circuit or as prototype purpose i just treat them as parasitics or "worst condition" testing. recently i tested 60V circuit and the FR4 gap between power and gnd rail start to spark like a very small firework, i suspect its the flux. but they went away in time. something to be learnt. for highly sensitive circuit and to avoid cross talk, unsuitable flux like this is highly not recommended, well any type of flux must be cleaned away on some circuit for maximum performance, even if they are advertised as no clean flux. imho fwiw..

[Ian.M]

Glad to see you eventually agree with the 90 years of industry experience of 'killed spirits of salt' (acid Zinc Chloride) flux damaging components, circuits and wiring. 

Take your ZnCl flux and put it in your plumbing toolbox - it has no place on an electronics bench. 

[Mechatrommer]

nothing beats by experiencing it first hand the hard way... i find it not so bad as most people talked in the net. i take your advice as a basic guideline to beginners. maybe i can keep this one to myself. its a good toothpaste and some skin cancer epidemic treatment, nonetheless.

[macboy]

It seems that Zinc Chloride is not too terrible for copper. After all, it is used with copper pipes all the time, and we don't have houses flooding all the time due to that.  The warning about ferrous metals should not be taken lightly. The stuff will destroy iron and steel. Consider that many (maybe most) component leads are made of soft steel, not solid copper! This is done because copper is expensive and steel is very very inexpensive by comparison. And of course your soldering iron tip is plain jane iron plated.  There are very good reasons that people warn strongly against using this type of flux.

BTW, it's been a long time since I've laughed as hard as I have when I saw that soldering iron tip. I have tips that are literally 15 years old that look and work like new. I almost exclusively use solder with Kester 44 RA (activated Rosin) flux core.

[WaveyDipole]

nothing beats by experiencing it first hand the hard way... i find it not so bad as most people talked in the net. i take your advice as a basic guideline to beginners.

False reasoning. Following sound proven advice from those who know is always better than blundering about and 'experiencing it firsthand the hard way'. Although a lesson might eventually be learned 'the hard way', this should always be the least desirable option. Research and application of tried and tested methods along with a consideration of appropriate safety considerations, should be the learning method of choice.

[helius]

Following sound proven advice from those who know is always better than blundering about and 'experiencing it firsthand the hard way'. Although a lesson might eventually be learned 'the hard way', this should always be the least desirable option.

There's an expression I heard at school, "Experience is a dear teacher, but a fool will learn at no other".

[mmagin]

its a good toothpaste and some skin cancer epidemic treatment, nonetheless.

You're thinking of zinc oxide

[yada]

Organic flux. R and RA don't or at least R should but doesn't have to be.
"MrCalsonslab" on you tube explains how they work.

[Ian.M]

Organic flux. R and RA don't or at least R should but doesn't have to be.
"MrCalsonslab" on you tube explains how they work.

That's a bit backwards.  R and RMA fluxes usually don't have to be cleaned, RA fluxes should be.