LAT Tests and Piece Part Screening

Radiation effects are normally tested on piece parts because of the great expense involved in testing complete units. The piece parts tested are those that are known from experience to be most susceptible to radiation. In addition, since relatively few facilities can perform tests such as SEU resistance, long lead times and high costs for testing are common.

After the piece parts have been documented, qualified and built, the parts may be subjected to a further screening known as Destructive Physical Analysis (DPA). DPA is a process wherein representative parts from a lot are dissected to verify construction meets detailed requirements. If the samples from the lot pass the DPA, the entire lot is accepted. If they fail, the entire lot is rejected or otherwise dispositioned. Many piece part specifications have specific DPA requirements. However, it is not unusual to impose other specifications, such as MIL-STD-1580, which have other DPA requirements. Sometimes, the specific requirements differ and a part that meets its detail requirement will not meet an overall DPA specification. Resolving these specification conflicts is a usual recurrence.

The economic and schedule result in requiring QCI and DPAs on discrete components often results in a full hybrid construction being less expensive and more readily available than discrete construction since element evaluation is a quicker process than QCI on many discrete items.