Thermal Shock Test: How It Works and What It's Used For

In summary: The thermal shock test subjects a component to rapid changes between extreme temperatures (e.g. -40°C ↔ +125°C) in times less than 30 seconds, to simulate the effect of abrupt environmental transitions. It is one of the most severe environmental tests and is used to qualify electronic, automotive, aerospace and battery. The reference standards are IEC 60068-2-14, MIL-STD-810 Method 503, JEDEC JESD22-A104 and ISO 16750-4. It requires a double-compartment chamber (two-zone or three-zone) or a rapid specimen handling system.

What is Thermal Shock?

Thermal shock is the physical phenomenon whereby a material, subjected to a very rapid temperature change, experiences internal mechanical stresses due to the differential expansion coefficient between its components. These stresses can cause cracks, delamination, weld fractures, metal detachment, and the failure of sealed joints.

Laboratory thermal shock testing reproduces these extreme transitions in an accelerated manner to test a product's resistance. The crucial difference compared to a simple thermal cycle is the speed of transition : in traditional thermal cycles, controlled ramps (1-15°C/min) are used in a single chamber, whereas in thermal shock, the transition from hot to cold occurs in less than 30 seconds , typically via two separate chambers and movement of the specimen.

Thermal Shock vs. Thermal Cycling: The Key Difference

Types of Thermal Shock

The standards mainly distinguish three test configurations:

• Air-to-Air (A/A) — the specimen is moved between two air chambers at different temperatures. This is the most common configuration for electronic components and automotive modules. Typical transfer time is 10–30 s.
• Liquid-to-Liquid (L/L) — the specimen is alternately immersed in two liquid baths (typically Galden or inert fluids) at opposite temperatures. Transition < 10 s. More severe, used for semiconductors, BGA soldering, ceramics.
• Three-Zone — three-zone system (hot / chamber / cold) to run complex profiles in sequence with differentiated dwell time.

Materials and Components Subject to Thermal Shock

• Electronic components: BGA solder joints, multilayer ceramic capacitors (MLCCs), plastic packages (mold compound cracking), flip-chip interconnects
• Automotive modules: ECUs, sensors, connectors — exposed to temperature changes between the engine hood (+85/+125°C) and the external environment (-40°C)
• Lithium batteries: separators, electrolytes, seals — tested according to UN 38.3 T2 (thermal test)
• Aerospace components: atmospheric transitions during takeoff/landing, shadow/sun transitions in orbit
• Ceramics and composites: cracks due to internal stresses caused by differential expansion
• Technical glass: laminated glass, LCD/OLED screens

Typical Thermal Shock Test Parameters

Thermal Shock Reference Standards

• IEC 60068-2-14 Na — Environmental testing: Change of temperature (rapid rate)
• MIL-STD-810 Method 503 — Temperature Shock, US military standard
• JEDEC JESD22-A104 — Temperature Cycling (Semiconductor Industry)
• JEDEC JESD22-A106 — Thermal Shock (Rapid Transition for Semiconductors)
• ISO 16750-4 — Climatic loads for automotive electrical/electronic components
• RTCA DO-160 Section 5 — Temperature Variation for avionics
• AEC-Q100 Grade 0/1/2/3 — Qualification of Automotive Integrated Circuits
• UN 38.3 Test T2 — Thermal test for lithium batteries for transport

How a Thermal Shock Chamber Works

A thermal shock chamber is typically configured with two superimposed compartments: a hot compartment and a cold compartment, constantly maintained at their respective test temperatures. The specimen is placed in a moving basket that, via a pneumatic piston or electric motor, moves between the two compartments in a matter of seconds.

The compartments maintain the target temperature even during transfer (recovery times are almost zero), unlike a single-compartment chamber that must cool or heat the entire cavity. This is why a shock chamber requires a larger refrigeration system than an equivalent climatic chamber, with cascading compressors (typically R507 + R23) to reach -70°C under significant thermal loads.

Liquid configurations (L/L) use two tanks of thermostated fluid and are more severe but less widespread, for reasons of fluid safety and specimen management.

Application Sectors

• Automotive: ECU, sensor, and LED headlight qualification according to ISO 16750-4 and AEC-Q100
• Aerospace and Defense: RTCA DO-160 and MIL-STD-810 tests for avionics
• Consumer Electronics: PCB Qualification, Connectors, and Displays for Outdoor Devices
• Batteries: UN 38.3 T2 test for lithium battery transport certification
• Semiconductors: JEDEC JESD22-A104/A106 for ICs and Packages
• Railway: Component qualification according to EN 50155 Class T3

The FDM Thermal Shock Chamber

FDM Environment Makers designs two- and three-chamber thermal shock chambers with an extended range of -80°C to +220°C and transfer times of <15 seconds. The models integrate:

• Pneumatically operated basket with capacity up to 500 kg
• revoFACE programmer with multi-step cycles and 21 CFR Part 11 compliant recording
• Independent control of the two compartments with uniformity ±1 °C
• Security system active in case of unauthorized opening

For custom needs (compartments with volume > 1,000 L, L/L shock, three-zone configurations), FDM creates customized chambers.

Discover FDM Environmental Chambers or contact us for technical advice.

For lithium battery safety testing according to UN 38.3, FDM builds battery test chambers dedicated to thermal cycling and abuse testing.

Frequently Asked Questions about Thermal Shock

What is the difference between thermal shock and thermal cycling?

The difference is the transition speed. Thermal cycling uses a single chamber with controlled temperature ramps (typically 1-15°C/min). Thermal shock , the transition occurs in less than 30 seconds, via two separate chambers. Thermal shock induces much more severe mechanical stress due to the instantaneous differential expansion between materials with different coefficients.

How many thermal shock cycles are needed to qualify a component?

It depends on the standard and the required degree of severity. IEC 60068-2-14 Na typically requires 5-100 cycles for standard tests, up to 1,000 for extended qualification. AEC-Q100 Grade 1 (automotive -40/+125°C) requires 500-1,000 cycles. MIL-STD-810 Method 503 defines three profiles with 3-100 shocks. For UN 38.3 T2 10 cycles are sufficient.

Air-to-Air or Liquid-to-Liquid Thermal Shock: Which One to Choose?

Air-to-Air is the standard for electronic components, automotive modules, batteries, and avionics—referenced by most standards (IEC, MIL, ISO). Liquid-to-Liquid is more stringent (transition < 10 s, instantaneous thermal shock) and is used for bare semiconductors, ceramics, and critical components for failure analysis. The JEDEC JESD22-A106 standards accept both, with distinct parameters.

Can a normal climatic chamber cause thermal shock?

No, not correctly. A single-well chamber, even with fast ramps (15°C/min), takes minutes to go from +125°C to -40°C—so it doesn't produce thermal shock stress. For IEC 60068-2-14 Na compliant testing, a two- or three-well chamber with transfer times < 30 seconds is required. Some high-end chambers have 20-30°C/min ramps with the option of "near shock" profiles, but they are no substitute for a true shock chamber for stringent qualifications.

Authoritative Sources

• IEC – International Electrotechnical Commission. International electrotechnical standards body, responsible for the IEC 60068 series for environmental testing.
• JEDEC Solid State Technology Associationpublishes JESD22-A104 and A106, the global benchmark for semiconductor thermal testing.
• DoD (MIL-STD-810), available on EverySpec. US military standard for environmental qualifications of defense and aerospace equipment.
• Automotive Electronics Council (AEC)issues AEC-Q100, which calls for thermal shock as a mandatory qualification test for automotive ICs.
• RTCA. American avionics standards body, publishes DO-160 Section 5 on temperature variations for aircraft equipment.

Other Frequently Asked Questions about Thermal Shock

How is “transfer time” defined according to IEC 60068-2-14?

IEC 60068-2-14 defines the transfer time t₁ as the interval between the instant the specimen leaves the first compartment and the instant it reaches the second compartment at the target temperature with a tolerance of ± 3 °C (Na method). For severe thermal shock tests, t₁ must be less than 30 seconds, ideally ≤ 10 seconds for air-to-air configurations. The dwell time t₂ (permanence in each compartment) must allow the core of the specimen to reach thermal equilibrium: typically 15-30 minutes for discrete electronic components, 1-3 hours for large modules or those with high thermal mass. The verification is carried out with thermocouples inserted into the reference specimen, and the cycle is validated only when the temperature measured in the core falls within ± 3 °C of the target. The shock chamber must guarantee a recovery time < 5 minutes after transfer to avoid extending the cycle.

What failure mechanisms does thermal shock accelerate?

Thermal shock mainly amplifies differential expansion failure modes: cracking of BGA and CSP solder joints due to CTE mismatch between package (17 ppm/°C) and PCB (18 ppm/°C FR4 in-plane, 65 ppm/°C out-of-plane); delamination of the mold compound from the silicon die; bond wire failure in plastic packages; fractures in multilayer ceramic capacitors (MLCC) due to mechanical stresses on the dielectric body. In ceramics and technical glasses, thermal shock induces thermal cracking due to exceeding the fracture toughness (K_IC). On lithium batteries, thermal shock accelerates the degradation of SEIs and polymer separators. The Coffin-Manson model (N_f ∝ Δε_p^(-c)) quantifies fatigue life, with exponent c typically 1.9-2.5 for SnAgCu solder joints. A typical acceleration factor between shock and thermal cycling is 5-15x for the same ΔT.

What are the differences between IEC 60068-2-14 Na and Nb?

IEC 60068-2-14 method Na is the rapid temperature change test with two chambers and specimen movement (or equivalent), transfer times < 30 seconds. It is used for the qualification of electronic, automotive (AEC-Q100), and aerospace (RTCA DO-160) components. The Nb method is the thermal cycle with a controlled ramp in a single chamber, with a variation rate of 1, 3, 5, or 10 °C/min (typically 3-5 °C/min). It is suitable for general aging tests where the focus is on simulating realistic transitions rather than shocks. The choice between Na and Nb depends on the expected operating condition: for automotive components exposed to sudden changes (engine hood), Na is required; for consumer or office equipment, Nb is sufficient. The less commonly used Nc (temperature gradient) method evaluates components with large thermal masses.

How is a thermal shock chamber qualified according to IEC 60068-3-5?

The metrological qualification of a shock chamber requires some extensions compared to a standard thermal chamber. Mapping according to IEC 60068-3-5 is performed separately on both chambers (hot and cold) under steady-state conditions, with 9 points for volumes < 2 m³. Additionally, the transfer profile with a reference thermocouple attached to the basket or specimen: the time taken for the specimen temperature to leave the tolerance range of the starting chamber and return to that of the destination chamber is recorded. Typical acceptance parameters are: transfer time < 30 s (more severe ≤ 10 s), recovery time < 5 min, temperature gradient between center and periphery < 3 °C. Annual calibration includes chamber probes, an electronic chronometer for the handling system, and a pneumatic pressure gauge if the basket is pneumatically operated. Certificates must be ACCREDIA traceable.