HASS

Once the HALT process has been completed, and the product has been ruggedized, we can develop a custom production screen to identify process defects. Running a HASS:

• Apply all stresses simultaneously. During vibration, continuously ramp temperature between brief dwells at extremes.
• HASS stress levels are based on HALT limits.
• Include any “critical” additional product stresses (as determined from HALT, e.g. product power).
• Conduct precipitation screen and evaluate product beyond operating limits, near destruct limits.
• Precipitate failures in product due to “latent” defects.
• Conduct detection screen and evaluate product near operating limits. Confirm and explore precipitation screen failures, and other hard and soft failures.

Test plan should be prepared for each test performed throughout the project and should have test related details like the number of units to be tested, the method of conducting the test, the stress conditions under which the test is to be run, the results to be recorded, etc.

Test plan need to have structure, illustrating the objective, resources provisioning for facilities, test equipment, time for tests, etc. The number of steps as given by Dimitri Kececioglu (1993) lists nine steps, which are

• Determine the test requirements and objectives.
• Review existing data to determine if any requirements can be met without testing.
• Review the list of tests to determine whether combining any tests would be economically feasible.
• Determine the necessary tests.
• Allocate the resources necessary to perform the tests.
• Develop test specifications, data handling and storage procedures. Review acceptance and qualification criteria. Establish procedures for making future changes in the test specifications.
• Assign the responsibility for conducting the tests, analyzing the results, and providing the overall integration of the testing program.
• Develop forms and procedures for reporting the test results.
• Develop procedures for maintaining the test status information throughout the entire testing program.