IEC 60068-2-1 & 60068-2-2 Temperature Testing

What do IEC 60068-2-1 and IEC 60068-2-2 test?

IEC 60068-2-1 and IEC 60068-2-2 are the two IEC 60068-2 environmental test methods that check whether equipment survives and keeps working across its rated temperature range. IEC 60068-2-1, commonly called Test A, is the cold test: low-temperature storage and operation. IEC 60068-2-2, Test B, is dry heat: high-temperature storage and operation. Both belong to the same IEC 60068-2 family of environmental test procedures, and together they cover the two ends of a product’s temperature spec.

Neither standard on its own tells you a product is “reliable.” What they tell you is narrower and more useful: whether a specific unit, built the way it’s actually built, holds its function and its physical integrity after being pushed to the cold and hot limits it’s rated for. That distinction matters because a lot of field failures trace back to a temperature extreme nobody tested for, not a design flaw that would have shown up at room temperature.

Why does temperature testing matter for product reliability?

Every material in a piece of electronic equipment expands and contracts differently as temperature changes. Solder joints, connectors, potting compounds, plastic housings, and printed circuit boards all move at their own rates. Cycle that enough times, or push it far enough in one direction, and the mismatch shows up as cracked joints, loosened connectors, warped enclosures, or seals that no longer seal.

Cold brings its own failure modes. Lubricants stiffen or gel. Battery capacity and output voltage drop. Plastics that are ductile at room temperature can turn brittle enough to crack under a load they’d normally shrug off. Electrical conductivity and semiconductor behavior shift as well, which is why a device that boots fine on the bench can behave unpredictably at minus 20.

Heat has the opposite but equally damaging set of effects. Components run closer to their thermal limits, insulation and adhesives degrade faster, and internal resistances change enough to push a circuit out of tolerance. Add condensation risk at the transition points, where a cold part suddenly meets warm humid air, and you get a second failure path that has nothing to do with the temperature extreme itself.

None of this shows up in a spreadsheet. It shows up as a warranty claim from a customer whose equipment sat in an unheated warehouse over a weekend, or a field return from an installation near a compressor that runs hot all summer. Temperature testing exists to catch those failure modes in a chamber, on a schedule the manufacturer controls, instead of finding out from a customer.

How does IEC 60068-2-1 (cold) work?

IEC 60068-2-1 covers low-temperature storage and operation. The specimen is conditioned at a controlled low temperature for a period long enough to reach thermal stability all the way through the unit, core included, and then evaluated against its performance criteria. The standard distinguishes between non-heat-dissipating specimens, which draw no power during conditioning, and heat-dissipating specimens, which may be powered either before or throughout the exposure depending on how the test is structured. That distinction exists because a powered device generates its own internal heat, which changes how it responds to a cold external environment compared with an identical unit sitting unpowered.

The point of running the cold test is to find out what actually changes in the product at low temperature, whether that’s a mechanical fit that shifts as materials contract, a battery that can’t deliver rated output, or a sensor reading that drifts outside spec. A pass means the unit met its defined criteria at the specified condition, not that it’s immune to cold in some general sense.

How does IEC 60068-2-2 (dry heat) work?

IEC 60068-2-2 mirrors that structure at the high end. The specimen is brought to and held at a controlled elevated temperature, again long enough to stabilize, and again with separate procedures depending on whether the unit dissipates its own heat and whether it needs to stay powered during the exposure. A component that runs hot under normal operation and also sits in a hot ambient environment faces a different thermal load than one that’s simply stored in a warm room, which is why the standard treats powered and unpowered conditioning differently.

Dry heat testing tends to surface a different category of problem than the cold test. Instead of brittleness and contraction, you’re looking for thermal runaway risk, insulation breakdown, drift in electrical parameters as components heat up, and mechanical distortion in housings or seals that were never designed to hold shape at the top of the rated range.

Why the powered vs. unpowered distinction matters

A heat-dissipating specimen tested unpowered only tells you how the materials themselves respond to the chamber temperature. Test the same unit powered, and you’re adding its own internal heat rise on top of the ambient exposure, which is closer to how it actually operates in the field. Choosing the wrong variant for a given product either understates the thermal stress it will see in service or wastes chamber time verifying a condition that never occurs in real use, so this is one of the first things to get right when scoping a test plan.

How should a manufacturer prepare for temperature testing?

A few things matter more than most people expect going in.

Test objectives need to be nailed down before the chamber is booked: what temperature range, what performance criteria define a pass, and whether the unit needs to be powered, unpowered, or both during exposure. Vague requirements produce vague results, and rerunning a test because the pass/fail criteria weren’t defined up front costs more time than defining them properly the first time.

Sample conditioning matters just as much as the test itself. A specimen that starts the test with residual heat or cold from shipping or storage won’t stabilize the way the standard assumes, which skews the result. Giving samples time to reach a genuine thermal baseline before the clock starts is not a formality.

Instrumentation and monitoring decisions belong in the test plan too. Where thermocouples get placed, how often data gets logged, and what counts as a functional check during or after exposure all need to be settled before the unit goes into the chamber, not improvised once it’s already conditioning.

What’s the difference between storage and operation testing?

This is a distinction worth getting right before a test plan is finalized. Storage testing evaluates whether a product survives being at a temperature extreme, unpowered, and then still functions normally once it’s returned to normal conditions. Operation testing evaluates whether the product actually works while it’s at that extreme. A product rated for wide storage temperatures but a narrower operating range needs both conditions defined separately, and conflating them is one of the more common ways a test plan ends up not matching what the product actually needs to demonstrate.

Getting temperature testing done right

IEC 60068-2-1 and IEC 60068-2-2 sound like a matched pair, and structurally they are, but the failure modes they catch are different enough that skipping one because the other passed is a mistake. Cold testing and dry heat testing answer different questions about the same product, and a design that handles one extreme cleanly can still fail the other.

Megalab is an ISO/IEC 17025 A2LA accredited test lab in Aurora, Ontario. Manufacturers working through temperature testing requirements for a new product, a redesign, or a customer spec that references IEC 60068-2 should build the test plan around the actual conditions the product will see in service, beyond the standard’s bare minimum requirements. That’s the difference between a chamber result that predicts field performance and one that just checks a compliance box.