Designing Electronics for Harsh Conditions

Estimated reading time: 5 minutes

We expect a lot from our products, especially our electronic products. Think about it: cellphones, wearables, medical devices—for some reason we think they should still work after being immersed in liquid, left outdoors in freezing temperatures or dropped on concrete from a standing position.

Sometimes that's the case. We drop a smartphone in the bathtub then stick it in a bag of rice and hope for the best. Many times, though, not even Uncle Ben's can save your poor, ill-treated phone. But that wasn't because the designer didn't anticipate your fumble.

Any product designer worth their salt is going to design products to protect the electronics to withstand any abuse you can think of—and much more. Take that smartphone or laptop computer for example. The product has to work whether the user is at a desk in Atlanta, a warehouse in California or a factory floor in Vietnam.

The Swedish company Handheld makes everything from rugged handheld devices to high-performance rugged tablets. The products usually look and operate like their everyday counterparts, but you might find them a little heavier or bulkier. The differences typically rest on tweaks in design and adjustments in materials used to make the product. 

The Handheld website is chock full of great information on how they create rugged products. Here are some of the ways they build computers for rugged use:

• Rather than using rotating hard drives, their computers have solid-state drives that are resistant to physical shock.
• Their computers contain stiffeners, often made from aluminum, to prevent interior components and boards from flexing on impact. The outer case and bumpers are designed to absorb the energy from a drop, minimizing internal damage. 
• Rugged computers displays use chemically strengthened glass to prevent scratches or cracks. The display is backlit to improve readability when outdoors. 
• Some computers include internal heaters for operation in extremely cold temperatures. The heater is able to get rid of condensation that can happen during a temperature change. 

Designing electronics for harsh conditions requires understanding the environment in which the product will operate, the customer's requirements, and common industry standards or specifications.

Examples of Harsh Conditions

• Extreme temperatures, both hot and cold
• Temperature variations
• Dust and other particulates
• Combustible conditions
• Moisture, humidity or submersion
• Regular or irregular vibration
• Sudden or continuous impact
• Power surges, either natural (i.e. lightning) or man-made

Questions to Ask

1. What is the product used for?
2. Where will it be used?
3. Are there temperature extremes?
4. How wide are temperature fluctuations?
5. Does this product need to be watertight or airtight?
6. How tight do those seals need to be?
7. What sort of physical pressure does it need to withstand?
8. How hard does the case need to be?
9. How light does it need to be?
10. Does the product need to be built to specific standards, i.e. Ingress Protection (IP), National Electrical Manufacturers Association (NEMA), Potentially Explosive Atmosphere (ATEX)?

Spec Standards

Products designed for harsh environments might have to meet the following standards:

Ingress Protection (IP) covers both moisture and particulates.

IP ratings are displayed using two digits. The first digit signifies the rating for dust/particulates, the second digit signifies the rating for liquids.

MIL STD 810g is a standard used by the U.S. military to test equipment in a variety of extreme conditions or shocks.

What is Required by MIL STD 810G?

The MIL STD 810g standard includes 28 different testing methods in scenarios that include:

• High temperature
• Low Temperature
• Rain
• Humidity
• Sand/Dust
• Immersion
• Vibration 
• Shock

Although this standard was initially created for products designed for military applications, MIL STD 810g has made its way into commercial application as well. However, no commercial organizations or agencies actually certify for MIL STD 810g. Chassis Plans, a producer of rugged computers and LCD displays for the military, produced an interesting white paper explaining MIL STD 810g, and how it has been applied (and misapplied) in commercial settings.

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