Physical Dimensions and Marking Permanency

Over the past few years, NJMET’s testing has encountered new techniques of blacktop marking that could easily pass the MIL Handbook resistance to solvents criteria. We have researched methods to test for these new techniques as well.

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Physical Dimensions
The height, length, width, and depth as well as arc angle, curvature measure, and pin-count of the devices are checked. This ensures all data meets the manufacturer’s specification and that there is no evidence that the components have been altered.
Marking Permanency
The purpose of this test is to verify that the markings will not become illegible on the component parts when subjected to solvents. (See picture.) Various military standard procedures are used that incorporate several chemicals mixed appropriately and in detail in accordance with the specifications. These chemicals consist of aliphatic alcohol, mineral spirits, ethyl-benzene, organic solvents, deionized water, propylene glycol monomethyl ether, or monoethanolamine.

Once the chemicals are mixed, the components are submerged in a three-phase process and analyzed in accordance with MIL-HBK-130 to uncover evidence of damage to the device and any specified markings. The analysis includes missing markings in whole or in part or those that appear, faded, smeared, blurred, or shifted to the extent that they cannot be readily identified from a distance of at least 6 inches with normal room lighting and without the aid of magnification.

NJMET: Mission Imposter electronic component with suspect markings
NJMET's Mission Imposter testing finds components with suspect markings.

In some cases, a strategic acetone wash is used to reveal sanding marks and facets of previous markings. Over the past few years, new techniques of blacktop marking have been discovered that could easily pass the MIL Handbook resistance to solvents criteria.  We have researched methods to test for these new techniques as well.

Author: josephfedericonj

Joseph Federico is Vice President and Director of Operations for NJ MET, Inc., located in Clifton, NJ. He speaks world-wide on current issues in Electronic Component Testing. Among his responsibilities at NJMET, Inc. is heading up its charity programs.