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MIL-STD 883 Moisture Resistance Testing

The moisture resistance test is used to evaluate the resistance of component parts and materials to deterioration. This deterioration results from the high-humidity and heat conditions of tropical environments. Most tropical degradation results from absorption of moisture vapor and films, and from surface wetting of metals and insulation. These phenomena produce many types of deterioration, including corrosion of metals, constituents of materials, and detrimental changes in electrical properties.

This test differs from the steady-state humidity test. It is effective in its employment of temperature cycling, to provide alternate periods of condensation and drying. This is essential to the development of the corrosion processes. It also produces a “breathing” action of moisture into partially sealed containers.

Increased effectiveness is obtained by use of a higher temperature, which intensifies the effects of humidity. Stresses caused by freezing moisture tend to widen cracks and fissures. Therefore this test includes a low-temperature sub cycle that helps to reveal otherwise indiscernible evidence of deterioration. Deterioration can be detected by the measurement of electrical characteristics or by performance of a test for sealing.

This test also provides for electrical loading of certain components, if desired. This is to determine the resistance of current-carrying components, especially fine wires and contacts, to electrochemical corrosion. Results obtained with this test are reproducible and have been confirmed by investigations of field failures. This test has proved reliable for indicating those parts which are unsuited for tropical field use.

What Test Equipment is Needed in the Ingress Protection Lab?

The apparatus needed for moisture testing is a temperature-humidity chamber capable of maintaining the cycles and tolerance necessary. Electrical test equipment capable of performing the appropriate measurements is also needed for ingress protection testing.

Keystone Compliance is a fully equipped  enclosure testing lab with significant experience in Method 1004.7 of MIL-883 moisture resistance testing. The following information is extremely technical in nature. Even though the language is from MIL-STD 883K, it applies previous versions of the standard. This includes MIL-STD 883G moisture resistance and MIL-STD 883H moisture resistance.

What is the Proper Procedure for Enclosure Ingress Testing?

Initial Conditioning

Before mounting specimens for water enclosure testing, the device leads should be subjected to a bending stress, initial conditioning. Devices in the moisture resistance testing lab may be subjected to initial conditioning as part of another test. In this case, the lead bend does not need to be repeated.

Initial Measurements

Prior to step 1 of the first cycle, the specified initial measurements should be made at room ambient conditions. When specified, the initial conditioning in a dry oven precedes initial measurements. The initial measurements should be completed within 8 hours of removal from the drying oven.

Number of Cycles

Specimens are subjected to 10 continuous cycles. Interruptions like equipment failure, or power interruptions may occur during IP code testing. When only one accidental test interruption occurs before completion of the cycle, the cycle is repeated and the test continues.

Accidental interruptions during the last cycle require a repeat of the cycle plus an additional uninterrupted cycle. Any intentional interruption, or any accidental interruption of greater than 24 hours requires a complete retest.

Sub cycle of Step 7

During at least 5 of the 10 cycles a low temperature sub cycle is performed. At least 1 hour, not more than 4 hours after step 7 begins, the specimens are removed from the humidity chamber. Or, the temperature of the chamber is reduced, for performance of the sub cycle. Specimens during the sub cycle are conditioned at -10°C +2°C, -5°C, with humidity not controlled, for 3 hours minimum.

The specimens should be held at -10°C, +2°C, -5°C, for the full period. After the sub cycle, the specimens should be returned to 25°C at 80 percent relative humidity (RH) minimum. This should continue until the next cycle begins.

Applied Voltage

During the moisture resistance test, the device should be biased in accordance with the specified bias configuration. This configuration maximizes the voltage differential between chip metallization runs or external terminals. It also minimizes power dissipation and utilizes as many terminals as possible to enhance test results.

Conditions

Specimens should not be subject to the radiant heat from the chamber conditioning processes. Circulation of air in the chamber is at a minimum cubic rate per minute 5x’s the volume of the chamber. The steady-state temperature tolerance is ±2°C of the specified temperature. Specimens weighing 25 pounds or less shall be transferred between temperature chambers in less than 2 minutes.

Final Measurements

Following step 6 of the final cycle, devices are conditioned for 24 hours at room ambient conditions.  Afterwards, either an insulation resistance test, or the specified 25°C electrical end-point measurements should occur. Electrical measurements may be made during the 24 hour conditioning period. However, any failures resulting from this testing are counted.

Retesting later in the 24 hour period to obtain an acceptable result is prohibited. No other test should be performed during the 24 hour conditioning period. Insulation resistance testing or 25°C electrical end-point measurements should occur within 48 hours of device removal from the chamber. When the insulation resistance test is performed, the measured resistance should be no less than 10 megohms.

If the package case is electrically connected to the die substrate by design, the insulation resistance test is omitted. The specified 25°C electrical end-point measurements should occur within 48 hours after removal of the device from the chamber. A visual examination and any other specified end-point electrical parameter measurements should also be performed.

What is the Failure Criteria of IP Code Certification?

Devices that undergo water ingress testing fail when:

  • Specified markings wholly or partly missing, faded, smeared, blurred, shifted, or dislodged to the extent that they are not legible. This examination is conducted with normal room lighting and with a magnification of 1X to 3X.
  • There is evidence of corrosion over more than 5 percent of the finish or base metal of any package element. Any corrosion that completely crosses the element when viewed with a magnification of 10X to 20X is considered a device failure.
  • Leads are found to be missing, broken, or partially separated.
  • Corrosion formations cause a bridge between leads or between leads and metal case.
  • When there is electrical end-point or insulation resistance test failure.

What Moisture Resistant Laboratory Should You Trust for Liquid Ingress Testing?

Keystone Compliance has been recognized as one of the best moisture resistance labs in the country. We employ experienced test engineers, knowledgeable in MIL-883G moisture resistance and MIL-883H moisture resistance. This combined with our fully equipped testing facilities ensure the best moisture resistance testing for your product.

Are you looking to get a moisture resistance certification for your product? Our test engineers understand moisture resistance compliance testing for commercial, military, and aerospace products. Contact us to learn why so many manufacturers rely on Keystone Compliance to meet their compliance testing needs.

MIL-STD-883 testing contains several test methods. For more information about these test methods, please click on one of the links below.