Environmental Reliability Test

Created: 06/09/2020Last Updated: 06/09/2020

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.

Overview

High Temperature Operational

    • This test examines the device proper operation under high temperature environment. This test is done generally as a few long duration thermal cycles from room temperature to the highest environmental temperature condition.
    • The passing criteria is that there is no form of mechanical, cosmetic, electrical and functional damages to the device

Low Temperature Operational

    • This test examines the device proper operation under low temperature environment. This test is done generally as a few long duration thermal cycles from room temperature to the lowest environmental temperature condition.
    • The passing criteria is that there is no form of mechanical, cosmetic, electrical and functional damages to the device

High Temperature Storage

    • 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

    • 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

    • Temperature: In this test, a short term thermal cycling duration done from 10s to 100s of cycles from lowest temperature to highest temperature conditions.
    • 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, room and normal humid condition, and hot and humid condition 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.
    • The passing criteria is that there is no form of mechanical, cosmetic, electrical and functional damages to the device.
    • 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.

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
    • Operational and Storage and two standards tests for temperatures
    • 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/