Temperature and humidity testing determines how components, subsystems and complete systems behave in severe environments that involve elevated temperatures and high or fluctuating relative humidity. The tests can be static with constant temperature and humidity, they can involve the cycling of both, they can be temperature-humidity bias tests (where the moisture is used to induce a failure in an electrical device) or some combination of all of these.
Among other things temperature/humidity tests study the effects of climatic changes on electronic components such as failures due to parameter shifts, mechanical failures (due to rapid water or frost formation), optical failures (fogging), water tightness (package) failures, material degradation (epoxy coatings, etc.) and much more. Temperature/humidity tests are a critical component of a complete qualification program. Many electrical components, while inexpensive to purchase, may be expensive to replace. For example, an LCD on an oil exploration device or a marine instrument can cause serious down time costs in a temperature/humidity related failure. Temperature and humidity combined testing extends to complete systems and finished products that extend beyond electronic components: copiers, computers, automobiles, satellites and even parachutes require temperature/humidity testing.
NTS has been performing climatic testing for over 50 years and we understand the wide breadth of temperature/humidity testing needs. Consequently our test chambers have been assembled and kept up to date to satisfy every conceivable requirement. Contact us today to learn more about how NTS can help you achieve your Temperature and Humidity Testing goals.
Thermal Cycling is the most common method of testing Solder Joint Reliability. Common test specifications include:
Thermal Cycling is usually performed at a transition rate of less than or equal to 20C per minute (usually 10 to 14C per minute) to avoid thermal shock with 1-3 cycles per hour. Per IPC-9701, temperature extremes are based on the product category with the low temperature usually 25C below the glass transition temperature (Tg) of the printed circuit board material. The electrical resistance is continuously monitored during testing using data loggers. Typically, the failure definition would be an increase of 20% above the nominal resistance. Testing is continued until 63% of failures occur to characterize the failure distribution. After failure detection, failure Analysis (including cross sections, SEM/EDS, X-RAY, dye and pry, etc.) is utilized to find the location and type of failure.