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

• • 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.

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/