Mechanical Shock Test - Mil-Std-883 Method 2002
The Mechanical Shock Test is a test performed to determine the ability of semiconductor devices to withstand moderately severe shocks resulting from suddenly applied forces or abrupt changes in motion encountered during mishandling, improper transportation, or field operation. Shocks of this type can cause devices to degrade in performance, or to even get damaged permanently. Shock pulses that are repetitive can also cause damage that is similar to those caused by extreme vibration. Mil-Std-883 Method 2002 is the most widely-used industry standard for performing this test.
Mechanical shock testing requires an apparatus that is capable of providing shock pulses of 500 to 30,000 g (peak), with the pulse width or duration ranging from 0.1 to 1 millisecond, to the body of the device package. The acceleration pulse shall be a half sine wave with a distortion not exceeding +/-20% of the specified peak acceleration. It shall be measured by a transducer and optional electronic filter whose cut-off frequency is at least 5 times the fundamental frequency of the shock pulse. The pulse width shall be measured between the 10% point of the peak acceleration during rise time and the 10% point during decay time. The pulse width shall have a tolerance of whichever is greater between +/-0.1 millisecond or +/-30% of the specified width.
The mechanical shock testing machine must be mounted on a sturdy and leveled surface. During testing, the device must be rigidly mounted or restrained by its case or body, with ample protection for the leads. Unless otherwise specified, the samples shall be subjected to 5 shock pulses, with the peak intensity and duration of the pulses complying with those defined by the specified test condition, in each of the following orientations: X1, X2, Y2, Y1, Z1, Z2. For devices with internal elements mounted with the major seating plane perpendicular to the Y axis, the Y1 orientation is defined as the one that tends to displace the elements from their mount. Unless otherwise stated, the test condition to be applied is Test Condition B.
Table 1 shows the various test conditions for mechanical shock testing as defined by Mil-Std-883 Method 2002. Test condition B shall apply, unless otherwise stated.
Table 1. Test Conditions for Mechanical Shock Testing
per Mil-Std-883 Method 2002
| Test Condition | g Level (peak) | Pulse Duration (ms) |
| A | 500 | 1 |
| B | 1,500 | 0.5 |
| C | 3,000 | 0.3 |
| D | 5,000 | 0.3 |
| E | 10,000 | 0.2 |
| F | 20,000 | 0.2 |
| G | 30,000 | 0.12 |
After the mechanical shock test has been completed, external visual inspection of the case, leads, and seals shall be performed at 10 X to 20 X. The marking shall also be inspected with or without magnification, but with the magnification no greater than 3 X. An illegible mark and/or any evidence of damage to the case, leads, or seals after the stress test shall be considered a failure. Additional specified measurements may also be done after this test.
The following shall be indicated in the acquisition document: 1) test condition applied if other than test condition B; 2) number and direction of pulses if other than specified; 3) electrical load conditions (if any); 4) measurements made after the stress test; and 5) measurements during test, if required.
Reference: Mil-Std-883 Method 2002
Reliability Tests: Autoclave Test or PCT; Temperature Cycling; Thermal Shock; THB; HAST; HTOL; LTOL; HTS; Solder Heat Resistance Test (SHRT); Other Reliability Tests
See Also: Reliability Engineering; Reliability Modeling; Qualification Process; Failure Analysis; Package Failures; Die Failures
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