MIL- STD-883F 2004 TEST METHOD STANDARD MICROCIRCUITS - 第72页

MIL-STD-883F METHOD 1012.1 4 November 1980 8 3.4 Calc ulati ons of R θ JR and t JR . 3.4.1 Cal culat ions of package t hermal r esis tance . The ther mal res ist ance of a mi croel ectr onic devi ce can be c alcul ated w…

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MIL-STD-883F
METHOD 1012.1
4 November 1980
7
3.3 Thermal response time, junction to specified reference point, t
JR
.
3.3.1 General considerations
. When a step function of power dissipation is applied to a semiconductor device, the
junction temperature does not rise as a step function, but rather as a complex exponential curve. An infrared
microradiometer or the electrical technique, in which a precalibrated temperature sensitive device parameter is used to
sense the junction temperature, shall be used to generate the microelectronic device thermal response time.
When using electrical techniques, in which the device heating power is removed before the TSP is sensed for measuring the
thermal response time, the cooling curve technique shall be used. The measurement of the cooling curve is performed by
heating the device to steady state, switching the power off, and monitoring the junction temperature as the device cools.
The cooling curve technique is based upon the assumption that the cooling response of a device is the conjugate of the
heating response.
3.3.2 Measurement of junction temperature as a function of time for the determination of t
JR
. The change in junction
temperature as a function of time resulting from the application or removal of a step function of heating power dissipation in
the junction(s) shall be observed using an infrared microradiometer with a response time of less than 100 µs, or electrical
equipment with a response time of less than 100 µs and sufficient sensitivity to read a precalibrated temperature sensitive
electrical parameter of the junction. During this test the device reference point temperature, as specified, shall be held
constant, the step function of power dissipation shall be applied or removed, and the waveform of the junction temperature
response versus time shall be recorded from the time of power application or removal to the time when the junction
temperature reaches a stable value.
The following data shall be recorded for this test condition:
a. Temperature sensitive electrical parameter (see section 3.2.3).
b. Infrared microscope spatial resolution (see section 3.2.2).
c. Peak, average, or region junction temperature as a function of time (see section 3.2.2 or 3.2.3 for details).
d. Case or mounting surface temperature T
C
or T
M
(usually 60°C ±0.5°C).
e. Power dissipation, P
D(Package)
or P
D(Element)
m in the package.
f. Reference temperature measuring point.
g. Mounting arrangement.
3.3.3 Typical test circuits for measurement of junction temperature as a function of time
. The circuits depicted in section
3.2.3 are also used for the measurement of junction temperature as a function of time. The clock pulse is varied to give the
required step of heating power and the TSP is monitored on a cathode ray oscilloscope. When an infrared microradiometer
is used, the measuring current and TSP sensing circuitry is disconnected.
MIL-STD-883F
METHOD 1012.1
4 November 1980
8
3.4 Calculations of R
θJR
and t
JR
.
3.4.1 Calculations of package thermal resistance
. The thermal resistance of a microelectronic device can be calculated
when the peak junction, average junction, or region junction temperature, T
J(Peak)
, T
J(Avg)
, or T
J(Region)
, respectively, has been
measured in accordance with procedures outlined in sections 3.1 and 3.2. If the total package capability is to be assessed,
then rated power P
D(Packages)
should be applied to the device under test. For quality control purposes the power dissipation in
the single test junction P
H(Element)
can be used in the calculation of thermal resistance.
With the data recorded from each test, the thermal resistance shall be determined from:
R
θJC(PEAK)
= T
J(PEAK)
- T
C
, junction peak-to-case;
P
D(Package)
R
θJC(Avg)
= T
J(Avg)
- T
C
, junction average-to-case; or
P
D(Package)
R
θJC(Region)
= T
J(Region)
- T
C
, junction region-to-case;
P
D(Package)
For calculations of the junction element thermal resistance, P
D(Element)
should be used in the previous equations. Note that
these thermal resistance values are independent of the heat sinking technique for the package. This is possible because
the case or chip carrier (reference) temperature is measured on the package itself in an accessible location which provides
a representative temperature in the major path of heat flow from the chip to the heat sink via the package.
3.4.2 Calculation of package thermal response time
. The thermal response time of a microelectronic device can be
calculated when the peak junction, average junction, or region junction temperature, T
J(Peak)
, T
J(Avg)
, or T
J(Region)
, respectively,
has been measured as a function of time in accordance with procedures outlined in section 3.3. If the total package
capability is to be assessed, then rated power P
D(Package)
should be applied to the device under test. For quality control
purposes the power dissipation in the single test junction P
D(Element)
can be used in the calculation of thermal response time.
With the data recorded from each test, the thermal response time shall be determined from a curve of junction temperature
versus time from the time of application or removal of the heating power to the time when the junction temperature reaches a
stable value. The thermal response time is 0.9 of this difference.
4. SUMMARY
. The following details shall be specified in the applicable acquisition document:
a. Description of package; including number of chips, location of case or chip carrier temperature measurement(s),
and heat sinking arrangement.
b. Test condition(s), as applicable (see section 3).
c. Test voltage(s), current(s) and power dissipation of each chip.
d. Recorded data for each test condition, as applicable.
e. Symbol(s) with subscript designation(s) of the thermal characteristics determined to verify specified values of
these characteristics, as applicable.
f. Accept or reject criteria.
MIL-STD-883F
METHOD 1012.1
4 November 1980
9
FIGURE 1012-1. Temperature controlled heat sink
.