Product Reliability

MEMSIC thermal accelerometer uses heated gas molecules as "proof mass" to detect motion and gravity. Since there is no moving parts used, MEMSIC thermal accelerometer could achieve ultra-high reliability, which has already been proved by mass volume market applications. MEMSIC thermal accelerometer is AEC-Q100 qualified.

MEMSIC has formal requirements for the development and implementation of reliability techniques that are to be applied to the research, design manufacture, test, application and service of all MEMSIC products. Our designs are guided by the following principles:

• Simplifying designs and reducing circuit components to the extent possible that is consistent with performance goals
• Re-using proven circuit components
• Making sure that appropriate end of life, fatigue and degradation of circuit components have been characterized for the use environment
• Performing DFMEA/FTA in the process of product development.

In production, product reliability can be degraded by handling processing, assembling and testing operations. The Quality Assurance Department is assigned the responsibility of preventing the degradation of reliability by process audits, QC inspections, mistake-proofing and other countermeasures.

Also performed are:

• Process FMEA
• Failure mode/effect determination on rejects from Pareto Analysis
• Product Reliability Monitoring tests including High Temperature Operating Life, High Temperature Storage, Temperature Cycling, Solderability, Solder Heat Resistance and Mechanical Tests

Product field data is gathered and evaluated to provide feedback on the reliability of MEMSIC products at customer sites and to maintain a data base to support continuous improvement.

• Field returns are electrically tested and opened to identify the failure mode and failure mechanism. Based on Pareto Analysis, Root Cause Analysis is performed on leading contributors by Engineering and Quality
• If needed, containment actions are taken as a preliminary action to reduce the frequency or severity of the problem prior to the full root cause investigation.
• As the result of Root Cause Analysis, improvement actions are planned and implemented.
• Improvement actions are verified through analysis and test.

In addition to field data, product reliability is also demonstrated through life testing. There are many long term reliability testing depending on the particular failure mechanism to be detected. MEMSIC uses the temperature acceleration based on the Arrhenius equation. In practice, life testing is conducted at an elevated temperature,the device's life at use temperature is calculated as:



where:

• tuse and ttest are Mean Time to Failure at test and use
• Ttest and Tuse are test and use temperatures in Kelvin (K)
• K is the Boltzmann¡¯s constant (8.617*10-5 eV/K) and
• Ea is the thermal activation energy for the specific failure mechanism (eV)

Because of the variety of products being tested, MEMSIC applies a standard activation energy of 0.7 eV in its calculation based on the process characterization and its knowledge of the process.