DocID025706 Rev 1

5/18

AN4428

Quality assurance

18

1.1.7

THB: temperature humidity bias

The device is biased in static configuration minimizing its internal power dissipation, and

stored at controlled conditions (ambient temperature and relative humidity). This test is

aimed to investigate the failure mechanisms activated in the die-package environment

caused by electrical field and wet conditions. It is mainly oriented to highlight typical failure

mechanisms of IC in these conditions like electro-chemical corrosion.

1.1.8

LTS: low-temperature storage

The device is stored in an unbiased condition at the minimum temperature allowed by the

package materials, sometimes lower than the min. op. temp. This is useful for investigating

the failure mechanisms activated by extremely cold conditions for prolonged time.

1.1.9

Repeated free-fall

The device is subjected to repeated mechanical drops. This test is performed in order to

check the robustness of the MEMS microphone when subjected to repetitive mechanical

stress.

1.1.10

MS: mechanical shocks

The device is subjected to 10000 g / 0.1 ms, 5 shocks for each axis. It is intended to

determine the compatibility of the component(s) to withstand moderately severe shocks as a

result of suddenly applied forces or abrupt change in motion produced by handling,

transportation or field operation.

1.1.11

VVF: vibration variable frequency

The device is subjected to a vibration with peak acceleration 20 g, 20 Hz to 2000 Hz where

three perpendicular directions have been applied. The vibration variable frequency test is

performed to determine the effect of vibration, within a specified frequency range, on the

internal structural elements.

1.1.12

MTC: moisture and temperature cycling

The device is subjected to cycled temperature and moisture exposure. The test serves to

investigate device robustness against the combined stress of moisture and temperature

cycles.