There are some points must be reviewed and considered before choosing a test chamber to buy.
Temperature range
A distinction between test chambers is the temperature ranges in which the chamber will operate. Most manufacturers have a standard high temperature range of 150˚C to 180˚C and low temperature range from 0 ˚C to -80 ˚C.
Humidity range
This is probably one of the most misunderstood topics when it comes to environmental test chambers. This is due to the fact that Relative Humidity percentage is temperature specific. For example, the amount of moisture in the air at 20˚C and 50% RH is not the same as 10˚C and 50% RH. As the temperature of air is reduced its ability to hold moisture is also reduced. Thus, for a given amount of water vapor in the air - the lower the temperature, the higher the RH
Temperature ramp rate
The requirements for temperature ramp rates (heating and cooling) continue to get faster and faster. By incorporating faster change rates, total tests time can be reduced. Products can also be thermally stressed at faster change rates which can identify reliability problems. However, be careful assuming the part temperature is changing at the same rate as the air.
