Ask the Experts
September 27, 2017 - Updated
December 14, 2008 - Originally Posted

IPA Cleaning Precautions

What safety precautions need to be taken when cleaning boards or electronic components with of IPA (isopropyl alcohol or isopropanol) cleaning solutions?


Expert Panel Responses

A) Precautions for Safe Handling and Use Steps If Matl Released/Spill: Wear proper protective clothing. Eliminate all sources of ignition. Stop leak if can be done at no risk. Use water spray to reduce vapaors. Absorb with sand or other non-combustible absorbent and place in container for disposal. Flush area w/water. Waste Disposal Method: Dispose of in accordance with applicable local, state and federal regulations. EPA/RCRA hazardous waste number d001 (ignitable waste) may apply to unused/uncontaminated product. Precautions-Handling/Storing: Keep container tightly closed. Store in a cool, dry, well-ventilated, flammable liquid storage area. Do not store near oxidizing materials. Other Precautions: Bond & Ground Containers When Transferring Liquid. B) Control Measures Respiratory Protection: Respiratory protection required if airborne concentration exceeds TLV. At concentrations above 1000 ppm, a chemical respirator with organic vapor cartridge is recommended. Above this level, SCBA is recommended. Use IAW 29 CFR 1910.134. Ventilation: Use general or local exhaust ventilation to meet TLV requirements. Protective Gloves: Neoprene Gloves. Eye Protection: Chemical Splash Goggles and/or Faceshield Other Protective Equipment: Uniform, apron. DLA-HMIS: eye wash station & safety shower. Work Hygienic Practices: Wash hands before eating, drinking, smoking, or using toilet facilities. Wash contaminated clothing before reuse.

Umut Tosun
Application Technology Manager
Zestron America
Mr. Tosun has published numerous technical articles. As an active member of the SMTA and IPC organizations, Mr. Tosun has presented a variety of papers and studies on topics such as "Lead-Free Cleaning" and "Climatic Reliability".

I assume you are speaking of cleaning PCBs with a brush and a small bottle of alcohol, or sometimes in an open top cleaning machine of some sort. In that case, you will find there are at three main problems with alcohol: First, alcohol is "hygroscopic." This means it absorbs water from the air, which dilutes the alcohol and weakens its ability to clean. Alcohol also is often diluted commercially by 20% or more, to keep the price down. This dramatically reduces its cleaning strength. Using weak, water-filled alcohol is a bad process that can lead to labor-intensive cleaning. Make sure you specify the purest, most water-free alcohol you can find. Secondly, alcohol is a very weak cleaner. It has a low Kb value and it saturates with flux residues at 2% by weight. So it takes a lot of solvent to successfully clean a typical circuit board. It's not the cost of the solvent that is the issue -- it's the cost of time lost cleaning inefficiently. So here are some steps you can take that will help cleaning work better:
  • Use clean bottles and clean brushes, and make sure your techs clean both items daily.
  • Make the techs clean with the board held at an angle, so the excess solvent runs off the board and doesn't stay and redeposit the contamination. If the solvent stays on the board, you're going to have dirty boards no matter how much the techs scrub.
  • Provide the techs with clean, lint-free wipes to absorb alcohol and flux residues. Make sure they use them, and dispose of them, rather than re-using them.
  • Consider upgrading to a more powerful solvent, a more sophisticated dispensing system and/or even an automated cleaner for faster, more reliable cleaning.
Special Note: In Circuits Assembly Magazine in Dec. 2007, Mr. Terry Munson published a detailed cleanliness study using SIR benchmarks. He found that cleaning using the "dip-and-brush" process actually made the boards dirtier and more prone to premature failure. So if this is your plan, well, maybe you should re-think it. Most people using alcohol develop problems with white residues, especially when cleaning lead-free materials. If these residues are streaky lines across the board, your techs are not rinsing thoroughly. Have them re-clean the board. But if the residues are an even, smooth layer of white film across a large area this usually indicates you have the wrong solvent for that flux. You will need to upgrade to a stronger solvent and the problem will go away. Now, about worker safety. This is the third weakness of alcohol cleaners. Alcohol has a flashpoint of about 15 degrees C -- around room temperature. In the U.S., anything with a flashpoint below 55 degrtees F / 15 degrees C is considered "extremely flammable" and a significant safety hazard. Do not use these cleaners in open-topped degreasers. Do not use them in uncontrolled aerosol sprays. Do not use them in open trays where they might spill. Do use them with good ventilation and keep fire extinguishers available in every area where they are used. Remember, alcohol burns with an invisible flame! You can walk right into a alcohol fire and never see the flames. This makes it, in my mind, an extremely poor choice when so many other, stronger and safer options are available.

Mike Jones
Vice President
Micro Care
Mr. Jones is an electronics cleaning and stencil printing specialist. Averaging over one hundred days a year on the road, Mike visits SMT production sites and circuit board repair facilities in every corner of the globe, helping engineers and technicians work through the complex trade-offs today's demanding electronics require.

The best advice I can offer is "don't use IPA". There are many other chemistries available that clean better, are much safer and environmentally friendly. First of all, IPA is a volatile organic compound (VOC) and is therefore a smog producer. Many areas have regulations prohibiting or limiting the use of VOCs and regulations are frequently changing so the appropriate regulating agencies should be consulted on an ongoing basis especially before incorporating an IPA cleaning process. IPA has a low flashpoint and warrants all surrounding electrical equipment and outlets to be explosion / fire proof. Appropriate equipment to provide vapor containment or safe exhaust should also be employed. At Smart Sonic, we make aqueous-based stencil cleaners. Over the years, we have replaced two IPA stencil cleaners that exploded. Many people feel the IPA machines are safe because the machines are pneumatic and the electrical controls are remotely located to prevent an ignition spark. However, the first IPA machine we replaced experienced an ignition spark due to a static discharge as the machine and operator were not properly grounded. The other machine experienced a mechanical spark because the stencil dislodged from its fixture and the revolving stainless steel spray nozzles hit against the metal stencil. Boom! Manufacturers of equipment using low flashpoint solvents such as IPA incorporate a fire extinguishing system within the machine. That alone should tell you something. These fire extinguishing systems usually work well - if they survive the explosion. On top of all of this, IPA requires personal protective equipment including: skin protection, eye & face protection, and respiratory protection, special storage, special transportation, and the empty containers are considered hazardous by RCRA. Your insurance carrier for fire and workers comp should also be advised of the use of flammable liquids.

Bill Schreiber
Smart Sonic Corporation
Mr. Schreiber developed the original ultrasonic stencil cleaning process in 1989. Obtained the only EPA Verification for specific parameters of Environmental Safety, User Safety and Cleaning Efficiency for a stencil cleaning process.

Firstly, IPA is a flammable solvent so you will have to ensure the area where the substrates are to be cleaned is safe. Also, if using an ultrasonic tank or any other electrical equipment, to assist the cleaning process, it should be flame proofed. As IPA is a volatile solvent there are workplace exposure limits for the chemical. These can be found on most safety data sheets. IPA should be used in a well-ventilated/extraction equipped area. A lot of useful information regarding safe use can be found on any standard health and safety data sheet for IPA.

Jade Bridges
European Technical Support Specialist
Electrolube Ltd
Jade Bridges is the European Technical Support Specialist for Electrolube. She is responsible for technical support within Europe, offering assistance to customers with product selection, implementation and after sales support across the range of Electrolube products. Her expertise is carried over from her position as R&D Manager for Electrolube, where she was responsible for the new product development and technical support across an array of chemical products for the electronics industry, including conformal coatings, encapsulation resins, thermal management products, contact lubrication and electronic cleaning solutions.

I recommend following the standard precautions for IPA. It is flammable, so keep heat and spark sources away from it. It dries the skin and is moderately hazardous to your body. IPA is a carrier which helps allow dissolved substances to penetrate into the body. Gloves, goggles, etc. should be worn. Do not breathe the fumes. Good ventillation is recommended. As far as the board and components go, it will wet and penetrate everywhere. The board should be rinsed and dried thoroughly when finished. When drying, the heat source chosen should be safe.

Mike Scimeca
FCT Assembly
Mike Scimeca created FCT Assembly after the purchase of Fine Line Stencil, Inc., and consists of two major operations: stencil manufacturing and the manufacturing of electronic assembly products such as solder paste, flux and solder bar.

IPA is a very stale cleaning agent. For personnel, eye protection should be worn at all times. IPA can cause dry skin where ever it comes in contact with the operator's skin. If the operator is sensitive to IPA, protective gloves can be worn. As always, have a working, inspected fire extinguisher available. IPA has a relatively low flash point and can easily cause a fire. Finally, make sure that IPA is chemically compatible with all other chemicals used in the assembly process. Chemical reactions can occur with certain substances. Check your MSDS for full compatibility and safety protocols.

Kris Roberson
Manager of Assembly Technology
Kris Roberson has experience as a machine operator, machine and engineering technician and process engineer for companies including Motorola, and US Robotics. Kris is certified as an Master Instructor in IPC-7711 / 7721, IPC A-610 and IPC J-STD 001.
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