Hobson Engineering’s hot-dip galvanised range of products assists in corrosion resistance
Zinc whiskers can pose significant problems if not addressed. Despite their innocuous name, they can cause considerable disruption in data centres. While monitoring temperature and having an effective layout can mitigate risks, it’s crucial to remain vigilant about this concealed threat.
Zinc whiskers are tiny filaments that form on steel surfaces electroplated with zinc. Zinc protects against corrosion, but the molecular stress from the electroplating process causes it to expand and crystallise to relieve the pressure. They start at only a few microns but can grow to several millimetres. It’s important to note that various surfaces develop whiskers at different rates and densities. Zinc whisker growth is unpredictable, but it is believed to be influenced by the conditions during the electroplating process itself.
The tiny shards can lead to catastrophic consequences for data centres. They can remain undisturbed for years on floor tiles and other structural supports. While they are more prevalent in older data centres that used electroplated zinc, they can form on this material anywhere, regardless of environmental conditions.
Hazards
Unchecked zinc whiskers can lead to everything from a short circuit to a complete system reset, resulting in downtime, repairs, and data loss. Even a gentle air current can be sufficient for them to detach from the surface. Given their microscopic size, they can easily evade filters and settle in sensitive hardware.
Zinc is a highly conductive metal created through electroplating, producing whiskers that function both as tiny wires and low-capacity fuses. When in contact with microcircuits, these whiskers can either connect currents or cause malfunctions by introducing their own charge. They also possess a DC fusing current, which is the amount of current required to melt the fuse. This is measured in milliamps (mA) and ranges from 10mA to 30mA.
Currents from short circuits can potentially vaporise the whisker, erasing all evidence and making it harder to identify the culprit. However, if the issue isn’t addressed, the electrical failures will only escalate.
Warning signs
The clearest sign of zinc whiskers is the equipment’s behaviour. If a particular piece of equipment continues to malfunction while the rest function perfectly, it’s likely an individual problem. However, if the equipment behaves erratically, zinc crystals may be the cause. Pay close attention to any changes in equipment performance following maintenance work or after a significant disturbance in the data centre, as this could indicate that many zinc filaments were dislodged.
Identification
Collect several samples from various spots in the room, particularly from areas that haven’t been disturbed or moved for a considerable time. Carry out the assessment away from equipment sensitive to the zinc filaments, and be cautious not to snap off any whiskers inadvertently. It may be useful to direct a light or laser onto the surface and tilt the material for a better examination. Use a magnifying glass to look for a dull, slightly shiny silver or dust-like texture.
Select a sample likely to exhibit zinc whisker growth. Trim a small section and use double-sided conductive tape or a similar material to secure it under the microscope. Tilt it vertically and direct light down onto the surface to look for any filaments emerging from the metal.
Removal
Cleaning or coating strategies unfortunately won’t resolve the issue. Cleaning is only a temporary fix since it doesn’t prevent future growth, and there’s no assurance it was done thoroughly. Additionally, the cleaning process can cause the whiskers to break loose, meaning they will ultimately end up back in the equipment. Coating merely applies a short-term solution to the problem, as the whiskers will continue to grow underneath. This can even cause the coating to chip, further contaminating the air.
The only way to resolve the issue is to address the root cause. Replace all zinc-electroplated materials with alternatives to minimise risk. Consider collaborating with an installation company and ensure that any zinc whiskers that break off during the replacement process cannot access the equipment. While working, wear high-efficiency particulate air (HEPA) masks to avoid inhaling pollutants. Use a HEPA vacuum to clean up any remaining particles and install HEPA filters throughout the data centre to prevent even the smallest particles from entering.
The data centre should be able to keep running throughout the process, and the time and resources spent replacing the zinc elements is more than worth it.
Prevention
Avoid using zinc electroplated materials, as that’s where the trouble begins. Find another method to protect susceptible steel and aluminium in data centres from corrosion, as rust brings problems. Hot dip galvanising is one of the best solutions, as it provides a corrosion-resistant layer of zinc by submerging the steel in molten zinc instead of electroplating, eliminating the risk of whiskers. Powder coatings are a less effective but cheaper alternative that suits applications requiring only light protection against rust.
Hobson’s hot-dip galvanised range is perfect for applications needing a high level of corrosion resistance. No evidence of zinc whiskers has ever been found on these products, making them suitable for sensitive applications.