Environmental Reliability Test

Introduction

A well designed product should operate properly under a wide range of environmental conditions in terms of temperature and humidity for its long term product life cycle.

Background

Temperature: for consumer electronics, environmental condition range from -20 to 60 degrees C.

Humidity: a relative humidity (RH) is used.

Detailed Overview

High Temperature Storage - Non operational

• • This test simulate conditions when the products are packaged up and in the transit such as over the sea, land, and air shipments.

  • For example, an electronic product delivered on the top of the shipment container is constantly exposed under the sun, and its environmental temperature is very hot.

  • This test generally lasts hundred of hours.

  • The passing criteria is that there is no form of mechanical, cosmetic, electrical and functional damages to the device

Low Temperature Storage - Non operational

• • This test simulate conditions when the products are packaged up and in the transit such as over the sea, land, and air shipments.

  • For example, an electronic product on the airplane cargo, and it's environmental temperature is cold.

  • This test generally lasts hundred of hours.

  • The passing criteria is that there is no form of mechanical, cosmetic, electrical and functional damages to the device

Cycling Test - Non operational

• • The purpose of the high-temperature and high-humidity test is to subject the hardware PCB and component packages to thermal expansion, ensuring the device's ability to withstand a wide range of environmental conditions. This thermal expansion puts strain on the contacts between the IC package and the landing pads on the PCB, which may lead to cracks on the hardware component footing. 

  • Thermal: In this test, a short term thermal cycling duration done few 100s of cycles from lowest temperature to highest temperature conditions such as -20 C to 60 C which standard to consumer electronics.

  • Temperature and Humidity: In this test, a few cycles of thermal cycling with humidity control are used to test the electronic product under combination of humidity and temperature.

    • Generally, we expect dry and cold condition (-20 C @ 5% RH), room and normal humid condition (25 C@ 25% RH), and hot and humid condition (60 C@ 95% RH) to be the worst  boundary conditions and the room temperature as the initial state.

  • The passing criteria is that there is no form of mechanical, cosmetic, electrical and functional damages to the device

Thermal Shocks 

• • Rapid change of temperature at from lowest to highest temperature conditions allows one to see to capture mechanical and electrical component failures.  This is generally test with PCBA

  • The passing criteria is that there is PCBA passes all board level functional/circuit tests and it can be assembled into the original enclosure.

  • Application: 

    • This is generally used for portable devices in which the product sees rapid environment change (e.g. taking a call using a cordless phone from a heated house to outside in the winter.

Thermal Soak Test

• Purpose: Accelerate hardware aging and evaluate device longevity.

• Procedure: Device placed in controlled chamber, exposed to high temperatures for extended time.

• Regular functionality checks during the test.

• Principle: Based on Arrhenius equation - higher temperatures accelerate aging.

• Benefits: Reveals potential weaknesses, enables design improvements.

• Ensures devices withstand real-world conditions and maintain optimal performance.

• Key role in quality assurance for manufacturers and instills confidence in consumers.

Standards:

• IEC 60068-2 specifies the environmental test methods for electronic requirements.

Summary & Conclusion

• • Environmental Reliability is a test of electronic equipment under different temperature and humidity conditions

  • Temperature is specified from lowest and highest temperature conditions.

  • Humidity is specified as relative humidity (RH) at each temperature 

  • It's a test of non-operational state of the device under test under various harsh conditions.

  • Stress tests includes thermal and humidity cycling and thermal shock tests.

Environmental tests are essential for electronic equipment to operate under inhabitable regions in the world.  

Reference & Further Reading

"IEC 60068", https://en.wikipedia.org/wiki/IEC_60068 

"IEC 60068-2", https://www.desolutions.com/testing-services/test-standards/iec-60068-2/