 |
 |
RELIABILTY
Reliability is one of the key factors that our customers look for in our products. The success stories illustrates some situations where our products have been put under severe conditions and have successfully passed these tests, where even most quartz crystal based devices have a tough time surviving.
|
|
|
|
|
|
|
|
Discera products are fabricated using the same semiconductor manufacturing techniques used in high-volume IC fabrication. Discera has forged co-development, manufacturing, and distribution partnerships with market leaders. Its micromechanical resonator oscillators set new benchmarks for shock resistance capable of surviving the g-shock of an air gun without any performance degradation. Discera’s high volume production Silicon MEMS oscillators tested under random vibration ranges up to 50G have proven to be reliable with high frequency stability over temperature cycling, aging, and vibration operation.
|
Low-cost, CMOS oscillators with miniaturized
silicon-based MEMS resonators have been out of research
laboratories and moving towards for high volume production. Silicon resonators not only offer more aggressive size reduction roadmaps versus quartz crystals, but also lead to a fully-integrated oscillator solution in the near future. The major concerns about silicon resonators are their reliability, including frequency stability over temperature cycling, aging, vibration operation, and shock resistance.
The following case studies show the reliability testing results based on volume manufacturing silicon based oscillators.
|
SHOCK RESISTANCE
One of the areas in which micromechanical resonator oscillators perform better over quartz crystal is the shock resistance. MEMS resonator typically has mass as small as 10-14kg and its stiffness is usually as high as tens thousand of N for high frequency structures. Simulations show being able to achieve up to 100,000g shock. The resonator itself will survive the g-shock very well.
However, the impact of the g-shock for the packaging
could be severe since the packaging contains most of the
mass. In this particular evaluation, we flip-chip resonator on top of an oscillator ASIC with solder balls as show below in Figure 6, which probably represent a worse case package compared to ceramic
package or plastic over-mold package.
If the oscillator experience 30,000g shock along
x, y, and z-axis, the z-axis stress and two shear stresses are
listed in Table I. Therefore, this type of oscillator will
survive 30,000g of shock.
A recent test has shown that MEMS oscillators can survived
the g-shock of an air gun. All of the tested 125MHz MEMS oscillator tested, did not show any performance degradation.
|
|
|
 |
Table 1:
Stress generated due to 30,000g shock in a BGA assembled MEMS oscillator.
Click on image to enlarge.
Learn more about this study in our whitepapers, click here for white paper.
|
|
|
|
|
VIBRATION OPERATION
Silicon MEMS oscillators were tested under random
vibration ranging from 2.84G to 50G. The output spectral
out of the oven for a thermal cycle test, as shown below, the frequency deviation across the temperature did not
change with time.
Based on results of a previous test, we know that the packaged resonator
passed the Height Temperature Storage Life (HTSL), this data indicates that the
resonator/oscillator package did not degrade with high
temperature storage.
With all the reliability data shown in previous sections,
and with the fact these oscillators have met the XO
specification including jitter, power consumption, voltage
variation, and temperature stability, MEMS-based silicon
resonator oscillators are now ready for commercialized shipping in timing and frequency
reference applications.
|
|
 |
Vibration Operation:
High temperature storage life + thermal cycling. Click on image to enlarge.
Learn more about this study in our whitepapers, click here for white paper.
|
|
|
|
|
|
|
