Electrical Contact Cleaning

Some cleaners, like WD40, contain oils that are left behind. That can be a good way to prevent oxidation, but it depends on your application and equipment. In some cases, it could be considered a contamination -- especially silicone oil, which tends to migrate.

Automotive cleaners like brake and carb cleaners are not ideal for cleaning contacts. Generally speaking, they are often very toxic, harsh on sensitive plastics and gasketing materials common in electronical devices, and are very flammable.

We recommend choosing a solvent engineered specifically for contact cleaning. Other solvent cleaners an be used, but be aware or the following factors:

• Spray force - Aerosol cleaners are generally used to penetrate into the tight areas around the contact and provide agitation.
• Dielectric strength - If you are cleaning energized (powered) equipment, use a cleaning solvent with a dielectric strength of 30 kV (30,000V) or higher. This prevents shorting the equipment. Dielectric strength is defined as the maximum electric field that the material can withstand under ideal conditions without breaking down. Breaking down in this sense is described as a failure of insulating properties, where the electricity breaks free of the conductors and burns a path through the weakest area of the insulating materials.
• Solvency / cleaning strength - The solvent cleaner needs to be strong enough to dissolve oil and other contamination.
• Flammability - If there is risk of flames or sparks, a nonflammable solvent is recommended.
• Evaporation rate - Since there isn't opportunity to wipe the solvent off the inner parts of the electrical device, fast evaporation is very helpful.
• Plastic compatibility - Electrical devices often contain plastics and gasketing material that can be damaged by harsh solvents.
• Additives - Some cleaners, like WD40, contain oils that are left behind. That can be a good way to prevent oxidation, but it depends on your application and equipment. In some cases, it could be considered a contamination -- especially silicone oil, which tends to migrate.

Check out "Ultimate Guide to Contact Cleaners".

Every organization using hazardous chemicals within their facility has the responsibility to equip their facility and personnel to maintain exposure levels below the TLV. Personal monitoring badges can be used to measure exposure of a specific material. Then, depending on the threshold limit and the application, exposure can be controlled with PPE like masks, face shields, respirators, and even coveralls. If they don’t reduce exposure below the recommended limit, you will need to consider a special ventilation hood or even containment booth. As you can see, as the exposure limit gets down to a certain level, the equipment required to safely use the solvent can get impractical. At that point, your best option is to consider a safer alternative.

The personal hazard associated with a solvent is often defined using Threshold Limit Value (TLV), which is the recommended average exposure in an 8-hour day, 40 hour work week. The lower the TLV of a particular substance, the less a worker can be exposed to without harmful effects. TLV is stated on the SDS of chemical products, in additional to recommended personal protection equipment (or PPE). The threshold limit value of a solvent is generally set by the American Conference of Governmental Industrial Hygienists (ACGIH). The unit of measure is Parts Per Million (PPM). 

Most contact cleaners are safe to use on printed circuit boards (PCBs) in electronic devices. Make sure the contact cleaner solvent is compatible with all components, connectors, and packaging by testing on a scrap part or inconspicuous area.

Hold object to be cleaned in vertical position so the solvent and soil can run off. Spray 4 - 6 inches (10-15 cm) from surface. Wash from top to bottom, allowing the liquid to flush away contaminants. For precision application, use with extension tube. Allow solvent to fully evaporate and dry before turning on the power to the device.

To improve the connection quality of an electrical contact or switch, you can remove oxidation or rust either mechanically and/or chemically. A brass or steel brush is the most common method of scrubbing off oxidation, although for sensitive contacts nylon is also used. With this method, take care to avoid damaging contacts and other components. It can be difficult to directly clean all the tight areas of electrical connectors and switches, so you may need to use some kind of chemical method. On the mild side, a mild acid like vinegar can be used, and other agents are offered for battery terminal cleaning, such as baking soda. Regardless of the cleaning material, care should be taken to rinse it off. A cleaner strong enough to remove rust could continue to work on unintended metal surfaces.

A contact cleaner (also called electrical cleaner, switch cleaner, electrical contact cleaner, and specific for automotive repair, battery terminal cleaner) is a solvent cleaner designed to remove contamination from electrical contacts, the conductive surfaces of connectors, switches and other electrical and electronic components with moving surface contacts. The goal is to quickly remove insulative contamination as quickly as possible, avoiding a lot of wiping and scrubbing if possible. Contact cleaning solvents are usually come in pressurized aerosol packaging for convenience and to provide a forceful spray that creates agitation and reaches into all the crevices of the connectors.

Generally, contact cleaners contain 100% solvent, which dissolves grease, carbon deposits, and other contamination, and allows it to run off. The solvent then evaporates, leaving a clean, conductive surface behind. Aerosol lubricants, like WD-40, have some cleaning ability, since the oil in the can has to be dissolved in a solvent. In this case, the solvent dissolves the contamination and a light oil is left behind. This oil can provide lubrication, allowing a connector to be inserted easily. It can also provide some hydrophobicity, preventing moisture from collecting in the connector and either causing a short circuit or corrosion. Chemtronics offers CircuitWorks Gold Guard Pen for this type of application. One problem with adding oil to a connector is it can collect dust and other contamination from the air around it.