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Preserve printed circuits

There is multiple factor who can reduce the lifespan of a printed circuit:

  • Moisture
  • Vapor
  • Corrosive solutions
  • Sand and dust
  • Mechanical and thermal stress from vibration, impact and temperature extremes

You can extend the lifespan of your printed circuits for many years depending on how you store and use them.

Corrosion

Printed circuits are susceptible to corrosion, which can be brought on by moisture, chemicals, or contaminants. To safeguard printed circuits from corrosion, it's essential to store them in a dry, clean environment.

It's also important to avoid exposing printed circuits to direct sunlight, as prolonged exposure can damage sensitive components.

Moisture

Have you ever opened a box with an electronic device, and you find that the box contains a small packet of silica gel beads? That silica gel is a desiccant. Its job is to prevent moisture adsorption on electronics by directly absorbing water from humid air that might infiltrate the device package. Desiccant packets can be included in device packaging during storage or during shipping to the end destination. Those same silica gel packets are placed in vacuum-sealed packages of chips to prevent moisture adsorption, particularly if those chips are moisture-sensitive.

Storage conditions

Store PCBs in a temperature-controlled environment between 20°C to 25°C. Avoid extreme temperature fluctuations.

Maintain low humidity levels, ideally below 65%. High humidity can lead to corrosion and damage to PCB components.

Wearing coton glove

Touching the pcb by hand may bring serious consequences, which may cause bad scrap of the PCB and end user reliability. Only the good habit of wearing gloves can still reduce or cure the "skin contact" on the PCB board.

Fingerprints are hand sweat stains. Its main components are as follows:

  • Water
  • Inorganic salts (such as Nacl, etc.)
  • Fatty oils (non-minerals)
  • Cosmetics and skin care products
  • Various types of dirt touched by bare hands (or dirty gloves)

Also your body can generate static electricity, which can discharge onto the PCB and damage its sensitive components. If you must touch a PCB with your bare hands, make sure your hands are clean and dry. You should also avoid touching the board's components directly. Instead, grip the board by its edges.

The best option, if you must handle them, it's to wear anti-static gloves, also known as electrostatic dissipative (ESD) gloves designed to prevent electrostatic discharge (ESD) damage to electronic components. ESD gloves are made from materials that either dissipate or conduct static electricity. Dissipative gloves allow static electricity to slowly flow away from the hand, while conductive gloves allow static electricity to flow away quickly. Both types of gloves can help to protect electronic components from ESD damage.

Howewer, not all gloves are suitable. For instance, rubber gloves can provide some protection against contamination and static discharge when handling PCBs, but they are not as effective as ESD-specific gloves.

Static is due to a potential difference between two parts, and the 'zap' is the potential evening itself out. The best way to avoid static discharge into your printed circuits is to make sure everything is at the same potential. The best way to do that is to make sure you and your parts are electrically connected to a common ground. i.e. touch your case while it's plugged in, before touching your parts. You can also ground yourself and wear an anti-static wrist strap to discharge static electricity, which can damage sensitive components.

Avoid handling printed circuits with dirty hands. If you must handle them, wear cotton gloves.

Restore oxidized circuit

In the event that a printed circuit board is already oxidized, it may be possible to restore it using alcohol. The method can be effective in removing corrosion from metals, flux residue, and other contaminants. However, it's crucial to use the right type of alcohol and follow proper procedures to avoid damaging the delicate components on the board.

For this, you need Isopropyl alcohol (91% or higher concentration) with cotton swabs or lint-free cloth to gently clean the affected areas of the PCB.

Isopropyl alcohol is generally compatible with most materials used in electronics. Isopropyl alcohol removes oils, adhesives, fingerprints, soldering flux and other contaminants, making it ideal for cleaning electronics. However, it is important to note that only alcohol with a grade of 90% or more should be employed on circuit boards and other internal electronics. Lower-grade alcohol contains too much water to be safe. It also evaporates too slowly and may leave behind unwanted residue.

Focus on removing corrosion, flux residue, and other visible contaminants but avoid excessive scrubbing, as this could damage delicate components.

For stubborn contaminants, use a slightly higher concentration of isopropyl alcohol (99% or higher) and allow the alcohol to soak in for a few seconds to loosen the contaminants. Don't forget to gently wipe away the dissolved contaminants with a clean, dry swab or cloth.

Use a magnifying glass to closely inspect the cleaned areas for any remaining contaminants necessary, repeat the cleaning process until the board is clean and free of visible contaminants.

Furthemore, before reassembling or using the device, it is also important to allow the PCB to dry completely.

Liquid exposure

If a circuit board has been exposed to water or other liquids, you need to disassemble it first to remove and prevent corrosion damage. Then, submerge it in Isopropyl alcohol (91% or higher concentration), clean with a soft-bristled tool and leave it to dry.

pH is a measure of the acidity or alkalinity of a solution. It is represented on a scale that ranges from 0 to 14, with 7 being neutral. Solutions with a pH value lower than 7 are considered acidic, while those with a pH value higher than 7 are considered alkaline or basic. The pH scale is logarithmic, which means that each whole number change in pH represents a tenfold change in acidity or alkalinity.

Either way, it's not good for electronic components, for instance you must avoid: lemon juice, sodas, fruit juice, bleach.

Also, even if the water has a neutral pH of 7, it's better to use Isopropyl alcohol. Isopropyl alcohol leaves no residue. It will dry much quicker and limit the corrosion after-effect. Water takes a lot longer to evaporate and depending on temperature and humidity may not completely evaporate at all. Additionally, undistilled water can contaminate the circuits with minerals.

Furthemore, neither rice nor any other so-called absorbent product will be effective! In the long term, they may even make the situation worse, because they have no effect on dirt.

Long term storage

If you plan to store electronics for an extended period, it's recommended to wrap printed circuits in protective material in a place without sunlight. You can also include some silica gel beads desiccant packs within the bags to absorb any moisture that may be present.

You can use bubble wrap, cardboard, or a plastic bag or even better an anti-static bag. Anti-static shielding bags are used to store, transport and protect electronic components and printed circuitry boards. The bags will protect electronic items from damage when electrostatic discharge occurs. Static electricity occurs more often when there are low amounts of moisture in the air.