Freescale Semiconductor, Inc.
Typical Test Conditions: Temperature per specified
Typical Test Conditions: Steam aging = 8 hours, Flux= R,
storage maximum and minimum, no bias, test time = up to
1000 hours.
Solder = Sn63, Pb37.
Potential Failure Modes: Pin holes, non–wetting,
Potential Failure Modes: Parametric shift in offset and/or
dewetting.
sensitivity.
Potential Failure Mechanisms: Poor plating, contamination.
Potential Failure Mechanisms: Bulk die or diffusion
defects, mechanical creep in packaging components due to
thermal mismatch.
OVER PRESSURE
This test is performed to measure the ability of the
pressure sensor to withstand excessive pressures that may
be encountered in the application. The test is performed from
either the front or back side depending on the application.
TEMPERATURE CYCLING (TC)
This is an environmental test in which the pressure sensor
is alternatively subjected to hot and cold temperature
extremes with a short stabilization time at each temperature
in an air medium. The test will stress the devices by
generating thermal mismatches between materials.
Typical Test Conditions: Pressure increase to failure,
record value.
Potential Failure Modes: Open.
Typical Test Conditions: Temperature per specified
storage maximum and minimum (i.e., –40 to +125°C for
automotive applications). Dwell time ≥ 15 minutes, transfer
time ≤ 5 minutes, no bias. Test time up to 1000 cycles.
Potential Failure Mechanisms: Diaphragm fracture,
adhesive or cohesive failure of die attach.
A pressure sensor may be placed in an application where
it will be exposed to various media that may chemically
attack the active circuitry, silicon, interconnections and/or
packaging material. The focus of media compatibility is to
understand the chemical impact with the other environmental
factors such as temperature and bias and determine the
impact on the device lifetime. The primary driving mecha-
nism to consider is permeation which quantifies the time for a
chemical to permeate across a membrane or encapsulant
corrosion can result.
Potential Failure Modes: Open, parametric shift in offset
and/or sensitivity.
Potential Failure Mechanisms: Wire bond fatigue, die
bond fatigue, port adhesive failure, volumetric gel changes
resulting in excessive package stress. Mechanical creep of
packaging material.
MECHANICAL SHOCK
Media related product testing is generally very specific to
the application since the factors that relate to the product
lifetime are very numerous and varied. An example is
solution pH where the further from neutral will drive the
chemical reaction, generally to a power rule relationship. The
pH alone does not always drive the reaction either, the
non–desired products in the media such as strong acids in
fuels as a result of acid rain can directly influence the lifetime.
It is recommended the customer and/or vendor perform
application specific testing that best represents the environ-
ment. This testing should be performed utilizing in situ
monitoring of the critical device parameter to insure the
device survives while exposed to the chemical. The Sensor
Products Division within Motorola has a wide range of media
specific test capabilities and under certain circumstances will
perform application specific media testing.
This is an environmental test where the sensor device is
evaluated to determine its ability to withstand a sudden
change in mechanical stress due to an abrupt change in
motion. This test simulates motion that may be seen in
handling, shipping or actual use. MIL STD 750, Method 2016
Reference.
Typical Test Conditions: Acceleration = 1500 g’s, orienta-
tion = X, Y, Z planes, time = 0.5 milliseconds, 5 blows.
Potential Failure Modes: Open, parametric shift in offset
and/or sensitivity.
Potential Failure Mechanisms: Diaphragm fracture,
mechanical failure of wire bonds or package.
VARIABLE FREQUENCY VIBRATION
A sufficient sample size manufactured over a pre-defined
time interval to maximize process and time variability is
tested based on the guidelines of the matrix shown above.
This test methodology is employed on all new product
introductions and process changes on current products.
A silicon pressure sensor has a typical usage environ-
ment of pressure, temperature, and voltage. Unlike the
typical bipolar transistor life tests which incorporate current
density and temperature to accelerate failures, a silicon
pressure sensor’s acceleration of its lifetime performance is
primarily based on the pressure and temperature interac-
tion with a presence of bias. This rationale was incorporated
into the development of the Pulsed Pressure Temperature
Cycling with Bias (PPTCB) test where the major accelera-
tion factor is the pressure and temperature component. It is
also why PPTCB is considered the standard sensor
operational life test.
A test to examine the ability of the pressure sensor device
to withstand deterioration due to mechanical resonance. MIL
STD 750, Method 2056 Reference.
Typical Test Conditions: Frequency – 10 Hz to 2 kHz, 6.0
G’s max, orientation = X, Y, Z planes, 8 cycles each axis, 2
hrs. per cycle.
Potential Failure Modes: Open, parametric shift in offset
and/or sensitivity.
Potential Failure Mechanisms: Diaphragm fracture,
mechanical failure of wire bonds or package.
SOLDERABILITY
In this reliability test, the lead/terminals are evaluated for
their ability to solder after an extended time period of storage
(shelf life). MIL STD 750, Method 2026 Reference.
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