Accelerated Life Testing is used to screen for early defects or model long-term failures. This technique is common in the semiconductor industry to verify the longevity of integrated circuits.
This model works well for that technology because electromigration is a common cause of device failure at end of life. Semiconductor companies have decades of data that has been used to refine their ALT and ensure it matches the actual performance of the device.
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The Challenges of Applying an Accelerated Life Testing
Applying accelerated life testing to a larger system comprised of several different mechanical and electrical technologies is much more challenging. For example, an automated machine like a pump skid contains semiconductors, PCBs, large passive electronics (capacitors, inductors and resistors), mechanical systems, as well as multiple lubrication and cooling technologies.
Creating an accurate ALT for this system may be impossible. Common strategies include high ambient temp testing and extreme vibration testing. In some cases it may be impossible to operate the system while the extreme conditions are applied. As a result, ALT is commonly performed in conjunction with ORT.
ORT typically involves operating a machine under more typical conditions for long periods of time well after production product is introduced to the market. It can be expensive to allocate machines for this type of testing. Testing units from every batch or build are too costly to even consider.
Collecting data post-production opens the door to verifying the pre-production stress results and identifying tests that should be added or eliminated from pre-production test. Executing Ongoing Reliability Testing (ORT) at the customer site is an option to any vendor that sells a machine with the intelligence to collect data.
Enabling ORT Testing
Enabling ORT testing in the field requires a communications back-haul solution and path to extract data sensor and status data from the system commonly done by extracting data from the local control unit or adding additional discrete sensors and connecting them to a test control unit.
The test control unit can be combined with the back-haul solution. This is commonly referred to as an edge gateway. Integrating these technologies together lowers cost and improves the reliability of the system by reducing the number of components.
The contract with the customer must state that telemetry data will be pulled off the machine. A cellular connection can be used to eliminate the need to leverage the end customers network connection, but our experience has shown that most customers will allow outgoing status messages if the solution is secure and provided by a reputable vendor.
HMS can support end customer meetings and provide certifications to ensure that the end customer has a clear understanding of the encryption and access control technology built into our remote data solutions.
These system topics should be considered when defining an in the field ORT solution:
1. How does the system respond to network outages?
a. Local data storage.
b. Multiple back-haul solutions
c. Can a service person download the data locally as an alternative to using the internet?
2. Is the system fixed one-way data collection?
a. End customers may accept fixed one-way solutions more readily
b. Bi-direction systems may need a local lockout feature
3. Reselling data
a. Can the data collected be used by the customer?
b. Is the data valuable to one of the component suppliers?
c. Would the data be valuable to a material supplier for the production system?
d. Is there a path to an additional revenue stream?
4. Reducing data bandwidth
a. Total data bandwidth can be reduced with careful planning
b. Direct impact on cellular costs
5. Is the system real-time or can the data be batch uploaded
6. Security
a. Device and Server verification
b. Data Encryption
c. User access and management
d. Logs