Isopropyl alcohol (IPA) is the standard choice for cleaning electronics. It dissolves oils, flux residue, and grime effectively, evaporates quickly, and leaves virtually no residue behind. The concentration you need depends on what you’re cleaning: 99% for internal components like circuit boards, 90%+ for thermal paste removal, and 70% for exterior surfaces like keyboard housings and laptop enclosures.
Why Isopropyl Alcohol Works Best
Isopropyl alcohol checks every box for electronics cleaning. It cuts through non-polar contaminants like oils, grease, fingerprints, and soldering flux. It evaporates faster than water or ethanol, which means less time for moisture to sit on metal contacts and cause corrosion. And at high concentrations, it leaves almost nothing behind on the surface.
Ethanol also works and is sometimes used in lab settings, but it’s slightly more expensive and often subject to denaturing regulations that add chemical additives you don’t necessarily want near sensitive components. For most people cleaning electronics at home or at a workbench, isopropyl alcohol is cheaper, easier to find, and the better default choice.
Concentration Matters More Than You Think
The percentage on the bottle tells you how much of the liquid is alcohol versus water. That water content makes a real difference when you’re working around circuits and metal contacts.
99% IPA is the gold standard for internal electronics. Use it on printed circuit boards, connectors, sockets, sensors, and anything with exposed circuitry. It penetrates tight spaces between components, dissolves contaminants, and evaporates fast enough that moisture never has time to cause problems. For PCB cleaning specifically, 99% is strongly recommended because lower grades can contain moisture, salts, or additives that leave conductive residues behind.
90-91% IPA is a solid middle ground. It works well for removing thermal paste from CPUs and heatsinks (Corsair recommends 90% or higher for this job), cleaning keyboard switches, and general component maintenance. The small amount of water content isn’t a concern for most tasks as long as you let parts dry fully before powering anything on.
70% IPA contains 30% water, which makes it a poor choice for circuit boards or connectors. That water can promote corrosion on metal contacts and leave moisture spots. However, 70% is perfectly fine for wiping down exterior surfaces, plastic housings, and cases. Apple explicitly approves 70% isopropyl alcohol wipes for cleaning the hard, nonporous surfaces of iPhones, MacBooks, iPads, keyboards, and other exterior surfaces.
What Not to Clean With Alcohol
Phone and laptop screens are the big exception. Most modern displays have an oleophobic coating, a thin layer that repels fingerprint oils and makes the screen feel smooth under your finger. Isopropyl alcohol is a powerful enough solvent to break down or completely strip this coating. Once it’s gone, your screen will smudge more easily and feel noticeably different.
Manufacturers typically recommend using only a soft, lint-free microfiber cloth dampened with water for screens, or a cleaning solution specifically designed for coated displays. Apple’s cleaning guidelines allow 70% IPA on exterior surfaces like the keyboard and enclosure but suggest a damp microfiber cloth for stubborn smudges on displays. Notably, Apple warns against using any alcohol-based cleaners on the Apple Vision Pro.
Also avoid products containing bleach or hydrogen peroxide on any electronics. These are too aggressive and will damage finishes and coatings.
How to Apply It Safely
Never pour or spray alcohol directly onto a device. Dampen your cleaning tool and apply it to the surface. This prevents liquid from seeping into ports, under buttons, or between display layers where it can pool and cause damage.
For most jobs, a lint-free microfiber cloth works well. For tight spaces around components on a circuit board, use lint-free foam swabs or cotton swabs. If you’re working around particularly sensitive components in a desktop build or repair, ESD-safe wipes are worth considering. These are made from materials that dissipate static electricity, reducing the risk of frying a component with an electrostatic discharge during cleaning. Standard lint-free wipes focus on minimizing fiber contamination but don’t offer static protection.
Always power off and unplug the device before cleaning. If you’re cleaning a circuit board or internal component, give the alcohol time to fully evaporate before reassembling or powering on. Under normal room conditions, 70% IPA evaporates in roughly 30 seconds to a minute. Higher concentrations dry even faster, but it’s good practice to wait a few minutes for internal components, especially in enclosed spaces where airflow is limited.
Thermal Paste Removal
Cleaning old thermal paste off a CPU or heatsink is one of the most common reasons people reach for isopropyl alcohol. Apply 90% or higher IPA to a lint-free cloth or coffee filter and gently wipe the surface. The alcohol dissolves the dried paste quickly. You may need a few passes for stubborn residue. Let the surface dry completely before applying fresh thermal compound.
Avoid using lower concentrations here. The extra water in 70% IPA makes the paste smear rather than dissolve cleanly, and you don’t want water sitting on the bare metal surface of your processor.
Storing Isopropyl Alcohol
High-concentration IPA is hygroscopic, meaning it actively absorbs moisture from the air. If you leave the cap off, your 99% bottle will gradually absorb water and become less effective. Recap it immediately after each use. Store it in a cool, dry, well-ventilated area between -4°F and 104°F. Don’t transfer it to squeezable wash bottles, as these allow humidity to contaminate the contents over time.
IPA is highly flammable, with a flash point of just 54°F (12°C). Keep it away from open flames, soldering irons that are still hot, heat guns, and any ignition source. Work in a ventilated area. The mild odor as it evaporates is a useful reminder: if the smell lingers, you need more airflow.