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MIL-STD 883 Temperature Cycling Testing

MIL-STD 883 temperature cycling helps determine the resistance of a part to extremes of low and high temperatures. Temperature cycling tests also determine the effect of alternate exposures to those extremes. All testing should be performed in a temperature cycling testing lab.

Keystone Compliance is one of the best thermal cycling labs, with significant MIL-STD 883 thermal cycling testing experience. Our test engineers understand the requirements of MIL-883 temperature cycling compliance testing. The following information is technical in nature, as it provides a summary of MIL-STD-883 thermal cycling. Below are some terms and definitions that will be used throughout.

Load refers to the specimens subject to thermal cycling testing and the fixtures that hold them. Maximum load is determined by using the worst-case load temperature with specific specimen loading. The maximum loading must meet the specified conditions. Monolithic or single block loads, may not be appropriate to use when load configuration reduces air circulation.

The monitoring sensor is located within the oven’s working zone. It is used, in conjunction with the Profile Data, to ensure testing is performed in accordance with temperature requirements. A temperature monitoring sensor ensures that systems meet the worst case load temperature periodic profiling/characterization. Thermal cycling compliance permits users to locate the monitoring sensor in any location within the profile area.

The worst case load temperature is the temperature of specific specimens or equivalent mass as indicated by thermocouples embedded in their bodies. A specimen as the individual piece or device that is being tested. These indicator specimens are located at the center and at each corner of the load. The worst case load temperature (point which reaches temperature last) is determined at periodic intervals.

Maximum load is the largest load for which the worst case load temperature meets the timing requirements. The working zone in the thermal cycling testing lab, is the volume in the chamber(s) where the temperature of the load is controlled within the specified limits.

Transfer time is the time that has passed between the initiation of the load transition from one temperature extreme and introduction to another. Dwell time is the time from the load of one extreme environment temperature until there is a transfer to the temperature environment.

What is the Appropriate Procedure for the Best Thermal Cycling Testing?

 In the thermal cycling lab, the test chambers used must be able to provide and control the specified temperatures in the working zone when loaded with a maximum load. The thermal capacity and air circulation must enable the working zone and loads to meet the specified conditions and timing. Worst case load temperature shall be continually monitored during tests by indicators or recorders. Direct heat conduction to specimens shall be minimized.

Specimens are placed in a position in the chamber so that there is no obstruction to the flow of air across and around the specimen. When special mounting is required, it will be specified. The specimen is then subjected to the specified condition for the specified number of cycles performed continuously. This test is conducted for a minimum of 10 cycles using test condition C in the table below.

One cycle consists of steps 1 and 2 or the applicable test condition and must be completed without interruption. Completion of the total number of cycles specified for the test may be interrupted for loading or unloading of device lots or because of power or equipment failure. However, if the number of interruptions for any reason exceeds 10 percent of the total number of cycles, the test must be restarted.

For the best temperature cycling testing, the total transfer time from hot to cold or from cold to hot must not exceed one minute. The load may be transferred when the worst case load temperature is within the limits specified in the table below. However, the dwell time may not be less than 10 minutes and the load must reach the specified temperature within 15 minutes (16 minutes for a single chamber).

  Test condition temperature
StepMinutesABCDEF
1
Cold
>10
-55 +0
       -10
-55 + 0
       -10
-65 + 0
       -10
-65 +0 -10
-65 +0 -10
-65 + 0
      -10
2
Hot
>10
85 + 10
         -0
150 + 15
           -0
150 +15
          -0
300 + 15
          -0
300 + 15
          -0
175 + 15
          -0

How Should Material Be Analyzed After Temperature Cycling Certification Testing?

After completion of the final cycle, an external visual examination of the marking is performed without magnification or with a magnification no greater than 3X. A visual examination of the case, leads, or seals is performed at a magnification between 10X and 20X. However, when this method is used for 100 percent the magnification for examination is 1.5X minimum. This examination and any other measurements or examinations are made after the final cycle, or after a group, sequence, or subgroup of tests.

Evidence of defects or damage to the case leads, or seals, illegitimate markings, examinations or failure of any specified end-point measurements is a failure. Damage to marking caused by handling during tests or fixturing is not a reason to reject the device.

After subjection to the test, failure of one or more specified end-point measurements or examinations constitutes a failure. Evidence of defects or damage to the case, leads, or seals or illegible markings will be considered a failure. However, damage to the marking caused by fixturing or handling during tests is not cause for device rejection.

What Thermal Cycling Laboratory Should I Trust?

Keystone Compliance has been recognized as one of the best temperature cycling labs in the country. Our experts are able to provide thermal cycling certifications for commercial, military, and aerospace products. Our temperature cycling laboratory is fully equipped to perform the best compliance testing for your product. Contact us to learn why so many manufacturers rely on Keystone Compliance’s compliance testing services.

MIL-STD-883 testing contains several test methods. For more information about these test methods, please click on one of the links below.