Freescale Semiconductor, Inc.
One could thus imply that the reliability performance
PULSED PRESSURE TEMPERATURE CYCLING WITH
indicates that vendor B has an order of magnitude improve-
ment in performance over vendor A with neither one seeing
an occurrence of failure during their performance.
BIAS (PPTCB)
This test is an environmental stress test combined with
cyclic pressure loading in which the devices are alternately
subjected to a low and high temperature while operating under
bias under a cyclical pressure load. This test simulates the
extremes in the operational life of a pressure sensor. PPTCB
evaluates the sensor’s overall performance as well as
evaluating the die, die bond, wire bond and package integrity.
The incorrect assumption of a constant failure rate over
time can potentially result in a less reliable device being
designed into an application. The reliability testing assump-
tions and test methodology between the various vendors
needs to be critiqued to insure a full understanding of the
product performance over the intended lifetime, especially in
the case of a new product. Testing to failure and determina-
tion of the lifetime statistics is beyond the scope of this paper
and presented elsewhere [2].
Typical Test Conditions: Temperature per specified
operating limits (i.e., Ta = –40 to 125°C for an automotive
application). Dwell time ≥ 15 minutes, transfer time ≤ 5
minutes, bias = 100% rated voltage. Pressure = 0 to full
scale, pressure frequency = 0.05 Hz, test time = up to 1000
hours.
INDUSTRY RELIABILITY STANDARDS
Reliability standards for large market segments are often
developed by “cross-corporation” committees that evaluate
the requirements for the particular application of interest. It is
the role of these committees to generate documents
intended as guides for technical personnel of the end users
and suppliers, to assist with the following functions: speci-
fying, developing, demonstrating, calibrating, and testing the
performance characteristics for the specific application.
One such committee which has developed a standard for a
particular application is the Blood Pressure Monitoring
Committee of the Association for the Advancement of
Medical Instrumentation (AAMI) [3]. Their document, the
“American National Standard for Interchangeability and
Performance of Resistive Bridge Type Blood Pressure
Transducers”, has an objective to provide performance
requirements, test methodology, and terminology that will
help insure that safe, accurate blood pressure transducers
are supplied to the marketplace.
Potential Failure Modes: Open, short, parametric shift.
Potential Failure Mechanisms: Die defects, wire bond
fatigue, die bond fatigue, port adhesive failure, volumetric
gel changes resulting in excessive package stress.
Mechanical creep of packaging material.
HIGH HUMIDITY, HIGH TEMPERATURE WITH BIAS
3
(H TB)
A combined environmental/electrical stress test in which
devices are subjected to an elevated ambient temperature
and humidity while under bias. The test is useful for
evaluating package integrity as well as detecting surface
contamination and processing flaws.
Typical Test Conditions: Temperature between 60 and
85°C, relative humidity between 85 and 90%, rated voltage,
test time = up to 1000 hours.
In the automotive arena, the Society of Automotive
Engineers (SAE) develops standards for various pressure
sensor applications such as SAE document J1346, “Guide to
Manifold Absolute Pressure Transducer Representative Test
Method” [4].
Potential Failure Modes: Open, short, parametric shift.
Potential Failure Mechanisms: Shift from ionic affect,
parametric instability, moisture ingress resulting in exces-
sive package stress, corrosion.
While these two very distinct groups have successfully
developed the requirements for their solid-state silicon
pressure sensor needs, no real standard has been set for the
general industrial marketplace to insure products being
offered have been tested to insure reliability under industrial
conditions. Motorola has utilized MIL-STD-750 as a refer-
ence document in establishing reliability testing practices for
the silicon pressure sensor, but the differences in the
technology between a discrete semiconductor and a silicon
pressure sensor varies dramatically. The additional tests that
are utilized in semiconductor sensor reliability testing are
based on the worst case operational conditions that the
device might encounter in actual usage.
HIGH TEMPERATURE WITH BIAS (HTB)
This operational test exposes the pressure sensor to a
high temperature ambient environment in which the device is
biased to the rated voltage. The test is useful for evaluating
the integrity of the interfaces on the die and thin film stability.
Typical Test Conditions: Temperature per specified
operational maximum, bias = 100% rated voltage, test time
= up to 1000 hours.
Potential Failure Modes: Parametric shift in offset and/or
sensitivity.
Potential Failure Mechanisms: Bulk die or diffusion
defects, film stability and ionic contamination.
ESTABLISHED SENSOR TESTING
HIGH AND LOW TEMPERATURE STORAGE LIFE
(HTSL, LTSL)
Motorola has established semiconductor sensor reliability
testing based on exercising to detect failures by the
presence of the environmental stress. Potential failure
modes and causes are developed by allowing tests to run
beyond the normal test times, thus stressing to destruction.
The typical reliability test matrix used to insure conformance
to customers end usage is as follows [5]:
High and low temperature storage life testing is performed
to simulate the potential shipping and storage conditions that
the pressure sensor might encounter in actual usage. The
test also evaluates the devices thermal integrity at worst
case temperatures.
Motorola Sensor Device Data
www.motorola.com/semiconductors
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