When soldering circuit boards, I always try to keep the soldering iron temperature below 260°C to avoid flux carbonization. I use leaded solder to make the process easier and try to minimize the use of extra flux through proper soldering techniques. As a result, the finished boards are usually very clean, often requiring no cleaning at all.
I strive to avoid additional flux as much as possible. Even when I do use flux, I prefer rosin-based flux. This means that the boards are not only clean and look like they don’t need cleaning, but also safe from a functional standpoint: the residual rosin flux is non-conductive. So, unless you’re extremely particular about cleanliness, you really don’t need to clean the board afterward.
However, there are still times when excessive rosin flux is used, leaving visible stains on the board after soldering — sometimes so dirty that it becomes unacceptable. In such cases, I use isopropyl alcohol (IPA) to clean the board. Using isopropyl alcohol instead of commercial PCB cleaner (aka “board wash”) is, in my opinion, a better and more economical option. Here’s my take and some experience to share.
Common “Lead-Free PCB Cleaners” on the Market
You may find products labeled “lead-free PCB cleaner” online, but this labeling is quite misleading. PCB cleaning solutions never contain lead in the first place. So why are they labeled “lead-free”?
What these products actually mean is that they can clean circuit boards assembled with Lead-Free Solder. In other words, “lead-free PCB cleaner” means it is suitable for cleaning boards produced using lead-free soldering processes, not that the cleaner itself is lead-free.
This label might be intended to highlight the product’s cleaning ability, or perhaps to mislead consumers into associating it with environmental friendliness.
Compared to “regular PCB cleaner,” these “lead-free” versions typically contain stronger solvents and surfactants, aimed at removing the more stubborn flux residues left behind by lead-free solder (which usually operates at higher temperatures and uses tougher flux). But if you’re not using lead-free solder in the first place, why pay extra for “lead-free” cleaner?
All I Really Need Is Regular PCB Cleaner
As a regular electronics hobbyist who uses leaded solder, I don’t need to spend extra money on “lead-free PCB cleaner.” Regular, cheaper cleaners work just fine for me.
In fact, most regular PCB cleaners consist mainly of ethanol and isopropyl alcohol. So rather than buying even the regular commercial cleaner, you can go a step further and mix your own cleaner — with just a bit of high-school chemistry knowledge.
Ethanol Is Not the Best Component for PCB Cleaning
Among the typical ingredients in common PCB cleaners, ethanol and isopropyl alcohol are the most prominent. However, only isopropyl alcohol is the truly effective ingredient.
Many people mistakenly believe that ethanol is the main cleaning agent. It’s true that ethanol is a decent organic solvent — but isopropyl alcohol is a much better one. Ethanol is mainly added for better fluidity, faster evaporation, and cost reduction.
What’s more, ethanol can actually have negative effects: it has a certain level of corrosiveness, and even so-called “high-purity” ethanol (like 95% alcohol from a pharmacy) still contains water, which can introduce conductivity and possibly damage your board.
Some hobbyists substitute 95% ethanol or even 60% medical alcohol from drugstores in place of PCB cleaner. Not only is this less effective at cleaning, but the water content may also lead to short-term or long-term reliability issues.
Isopropyl Alcohol: The Smarter Alternative
If you don’t want to buy commercial PCB cleaner, then don’t use ethanol either. Go for isopropyl alcohol instead — it’s the smart choice. You can easily purchase analytical-grade isopropyl alcohol from chemical supply stores.
You’ll be pleasantly surprised by how cheap it is. Isopropyl alcohol is the real active ingredient in most PCB cleaners. It effectively dissolves and removes rosin residues. It’s safe, gentle, odor-free, non-conductive, and won’t damage IC components, even those with plastic housings.
Interestingly, isopropyl alcohol is already part of your daily life — it’s the key ingredient in most waterless hand sanitizers you carry around when traveling.[1]
Before You Go
If you’re convinced and ready to switch to isopropyl alcohol as your go-to PCB cleaner, here are two final tips:
- Like all alcohols, isopropyl alcohol is flammable, so make sure to store it away from heat sources or open flames.
- When buying from a chemical supplier, distinguish between industrial-grade and analytical-grade isopropyl alcohol. The former may contain impurities and is meant for general-purpose cleaning; the latter is lab-grade and contains no contaminants, making it the better option for electronics cleaning.
References
- WHO. Guide to Local Production: WHO-recommended Handrub Formulations. World Health Organization. https://iris.who.int/bitstream/handle/10665/332005/WHO-IER-PSP-2010.5-eng.pdf?sequence=1