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MIL-STD 883 Thermal Characteristics Testing

MIL-STD 883 thermal characteristics testing helps determine the thermal characteristics of microelectronic devices. This includes junction temperature, thermal resistance, case and mounting temperature and thermal response time of the microelectronic devices. The following information is extremely technical in nature as it provides a summary of MIL-883 thermal characteristics testing. Below is a list of definitions and symbols of terms derived from MIL-STD 883 temperature section.

The case temperature is the temperature at a specified accessible reference point on the package in which the microelectronic chip is mounted. The mounting surface temperature is the temperature of a specified point at the device-heat sink mounting interface. The junction temperature denotes the temperature of the semiconductor junction in the microcircuit in which the major part of the heat is generated.

The thermal resistance of the microcircuit is the temperature difference from the junction to a reference point on the package, divided by the power dissipation (PD). Power dissipation is the power dissipated in a single semiconductor test junction or in the total package.

Thermal response time is the time required to reach 90 percent of the final value of junction temperature change. This change is caused by the application of a step function in power dissipation when the device reference point temperature is held constant. Temperature sensitive parameter (TSP) is the temperature dependent electrical characteristic of the junction-under test. This can be calibrated with respect to temperature and subsequently used to detect the junction temperature of interest.

What is the Appropriate Procedure for the Best Thermal Characteristics Testing?

All MIL-883 temperature testing should take place in an equipped temperature testing lab. Keystone Compliance is one of the best temperature testing labs in the country. Our test engineers have an in-depth knowledge of the procedure for MIL-STD-883 temperature testing.

Direct measurement of reference point temperature, TC or TM is necessary for mesrug microelectronic device thermal resistance or thermal response time. The reference point temperature is measured at the package location of highest temperature which is accessible from outside the package. In general, that temperature is measured on the surface of the chip carrier directly below the chip.

The location should be as near the chip as possible and represent a temperature in the path of heat flow from the chip to the heat sink. The surface may be altered to facilitate this measurement. This alteration can not affect the thermal resistance within the package by more than a few percent.

Case temperature, TC requires the microelectronic device to be mounted on a temperature controlled heat sink. This is so that the case temperature can be held at the specified value. A thermocouple is attached as near as possible to the center of the bottom of the device case directly under the chip or substrate. A conducting epoxy may be used for this purpose.

In general, for ambient cooled devices, the case temperature should be measured at the spot with the highest temperature. The thermocouple leads should be electrically insulated up to the welded thermocouple bead. The thermocouple bead should be in direct mechanical contact with the case of the microelectronic device under test.

The mounting surface temperature (TM) is measured directly below the primary heat removal surface of the case. It is measured with a thermocouple at or near the mounting surface of the heat sink. The surface of the copper mounting base must be nickel plated and free of oxides.

What Details Should Be Recorded Following Temperature Compliance Testing?

Certain details should be specified in the applicable acquisition document. For example, record the description of a package. Include the number of chips, the location of case or chip carrier temperature measurement(s), and the heat sinking arrangement. Document the test condition(s) of the thermal characteristics laboratory including the test voltage(s), current(s) and power dissipation of each chip.

Include the recorded data for each test condition, as applicable in line with the thermal characteristics certification. Report the symbol(s) with subscript designation(s) of the thermal characteristics determined to verify the specified values of these characteristics. Finally, make note of the acceptance and rejection criteria for thermal characteristics compliance testing.

What Thermal Characteristics Testing lab Should I Trust?

Keystone Compliance has been recognized as one of the best thermal characteristics labs in the country. We employ expert test engineers and properly equip our temperature laboratory to provide the best testing for all products. Keystone Compliance is the best temperature lab to receive temperature certifications from for all 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.