Anyone knows what flux type FXM1 means? - Page 1
Forum section: electronics / projects

author: cybermaus
author_rank: Frequent Contributor
timestamp: September 20, 2025, 07:56:52 pm
content: So I was running low on 60/40 solder wire, seeing the plastic in the centre, and did not want to try China sources (not again anyway)So I bought some locally. I thought it was pretty "normal" solder, because hey, all I know is leaded or lead free, and 60% vs 63%.For what it is worth: 60/40 rosin core 0.5mmHowever, the stuff is giving me a headache. Pretty quickly. And takes all night to clear my head. Yes, I have air suction and filter, still I cannot stand the stuff.Normally I have no problem with soldering. Ok, simply not use it, easy decision. But still, I wonder what it is I boughtSome searching showed the stuff I normally use has "ROM1" flux, and I do not notice it, so fine.Most of the stuff I find in shops in NL (if they even list it) also have ROM1, seems to be the standard.But somehow I managed to buy "FXM1". Not even sure how I managed to get that, because currently I cannot find it anymore.Except this one store in Poland, see image, but also links belowI found this flux code reference, where flux types codes are explained, but FXM1 is not in therehttps://www.almit.de/export-reports/pdf-en/FLux_types_in_accordance_with_IPC-J-STD-004.pdfExtract below, it list several types, but not FXM1What kind of stuff did I buy (and will not use). Something really unhealthy, or is this just a personal sensitivity?Any ideas? The M1 probably means moderate strenght low halide, just like all the other codes with M1. But what is FX?Polish shop with image:https://allegrolokalnie.pl/oferta/cyna-05kg-spoiwo-lutownicze-sn60-fxm1-fondam-franceAnother polish link:https://sprzedajemy.pl/cyna-firmy-radiel-fondam-sn60pb40-fi-1-5-500g-france-jozefow-4-0010c9-nr67730427

author: aeg
author_rank: Regular Contributor
timestamp: September 21, 2025, 12:14:04 am
content: I found this document in Russian:https://delta-n.ru/Info/RADIEL.pdf"FXM – некоррозионный безотмывочный безгалогеновый флюс c кислотным числом 380;"Translation: "non-corrosive, no-clean, halogen-free flux with an acid number of 380"

author: tooki
author_rank: Super Contributor
timestamp: September 21, 2025, 12:49:00 pm
content: Quote from: cybermaus on September 20, 2025, 07:56:52 pmFXM1 isn’t a standard flux code. It’s a manufacturer-specific model designation.Googling“FXM1” fluxgot several hits that provide some insight:-http://www.eurosolder.com/en/fxm1-solder-wires-low-residues.php-https://bltcircuitservices.co.uk/wp-content/uploads/2016/02/BLT-Brochure.pdfpage 24These all indicate it is a rosin-based no-clean formulation.FONDAM (or at minimum, its products and formulations) wasacquired by MBO in 2008, so it is possible that MBO itself might be able to provide information:MBO (France, HQ):https://mbosolder.com/en/home/MBO UK:https://www.mbouk.co.uk/

author: cybermaus
author_rank: Frequent Contributor
timestamp: September 21, 2025, 03:34:18 pm
content: Quote from: tooki on September 21, 2025, 12:49:00 pmThanks for that MBO UK doc. It shows that the solder *should* be pretty standard Rosin core. But then why is it giving me such a weird headache-adjacent feeling?Anyway, I am a hobbyist with two of their 100 gram rolls. I do not think I shall be taken seriously when inquiring with them.

author: tooki
author_rank: Super Contributor
timestamp: September 21, 2025, 04:28:58 pm
content: Quote from: cybermaus on September 21, 2025, 03:34:18 pmI assume you mean the PDF from BLT Circuit Services. I didn’t link to an MBO PDF of product data.No, that is not what it shows. It’s a rosin-basedno-cleanflux, which means it is NOT a “traditional” rosin flux. To work with the much smaller amounts of flux used, no-clean fluxes tend to use different activators. They’re notorious for being much more aggressive to the nose.If it’s giving you a headache, then you definitely need to use it with fume extraction. Or just order some traditional rosin solder (for example, Kester 44) from Digikey or Mouser.Quote from: cybermaus on September 21, 2025, 03:34:18 pmWho knows? They’re not one of the bigger solder manufacturers (the UK subsidiary even less so), so they may be more responsive.