Same total dose, more damage when delivered slowly
Many bipolar and BiCMOS linear and mixed-signal parts (op-amps, comparators, voltage references, regulators) show more degradation when a given total ionizing dose (TID) is delivered at a low dose rate than when it is delivered quickly. A part that passes a high-dose-rate test at 100 rad(Si)/s can drift out of specification when tested at low dose rate.
Condition D is a standardized test rate, not the orbital dose rate. Real dose rates in orbit are typically much lower still. Low-dose-rate testing is a practical compromise between space-like conditions and a usable schedule.
| Illustrative test target | Days at 10 mrad(Si)/s | Weeks |
|---|---|---|
| 10 krad(Si) | 11.6 | 1.7 |
| 20 krad(Si) | 23.1 | 3.3 |
| 30 krad(Si) | 34.7 | 5.0 |
| 50 krad(Si) | 57.9 | 8.3 |
| 100 krad(Si) | 115.7 | 16.5 |
Irradiation time only. The dose a program needs depends on orbit, mission duration, shielding and design margin.
Low-dose-rate tests decide schedules
Because a low-dose-rate exposure runs for weeks or months, a source position is tied up for the whole test. When capacity is short, lots wait for an opening and qualification dates slip. Planning the exposure window early, and reserving it, is often the difference between an on-time and a late parts list.
Guides and tools
TM 1019 Condition D explained
The low-dose-rate condition in MIL-STD-883 Test Method 1019: rate, filter box, bias and how it fits a qualification plan.
Read the guide →ELDRS test duration calculator
Exposure time, calendar time and completion date for any dose and dose rate.
Open the calculator →Radiation testing glossary
Plain definitions of TID, ELDRS, krad(Si), Condition D, filter box, rebound and more.
Browse the glossary →