Technical Success Stories: Delkin Matches Product & Testing to Unique Environmental Requirements
CompactFlash as a form factor has been a stable, industrial, storage medium used by many embedded product OEM’s for more than 20 years. The standard uses a simple, 50 pin connector designed to mimic a HDD in its interface. The ruggedness and simplicity of the design, and ease of product testing has made it one of the most popular choices for rugged storage. The combination of allowing four physical chips, and encasing the memory in a rugged container, made it fast, high capacity and able to be used in environments challenged by dirt and extended temperatures.
When MLC (Multi level Cell) flash was introduced, it looked like a promising development for CF cards. Finally there was a way to enjoy all the benefits of CF, with a less expensive technology flash. MLC CF cards became the standard in Consumer products, and even a few embedded customers began to consider the technology, despite the reduced temperature range and less Program/Erase cycles inherent to the new MLC flash.
“We looked for ways to make our Dashboard cameras more rugged when we first introduced them. We knew this market segment that used our product was both cost and budget time-frame sensitive, and we wanted to have a reliable product that has high endurance, and could be used across a customer’s entire fleet. We discussed the quoted temp specifications for the cards when using MLC, but our thinking was the product was in an environment where the temperature in the vehicles could not exceed what humans would consider comfortable, by using either Air Conditioning or heat, the environment would not exceed 0-70°C”
“When the failures started to appear, we were sure it was a CF card design issue or flaw, we investigated what state the card was in on start-up, and were not able to determine what was causing the failure. When our supplier could not find any issues with the CF cards, one of our Engineers called Delkin”
The Camera maker called a Delkin Sales Specialist and described the problem. The salesperson discussed the issue with her supervisor and agreed there might be a chance to work with the customer in the future, and decided to at least discuss the issue with the technical team at Delkin. If they were able to suggest some product testing or alternate diagnosis ideas, it would at least help the camera maker out of a bind, and may lead to some business down the road.
The Delkin Customer Applications team often gets calls from people using other brands of cards with problems. Usually the conversation needs to be limited, as it is difficult to diagnose a problem with a card not of our design and manufacture. We can and do often at least give some ideas or theorize on possible things to test in order to find the root cause.
During a brief discussion about the host, Operating System, environment, and the details around the failed units, it was discovered the failed units were all from extreme heat environments. Yuma AZ, Palm Springs CA and Phoenix AZ. Despite nationwide sales of this camera, no failures were encountered in areas of moderate or cold environments. A theory around temperature developed.
Delkin MLC CF cards were tested in temperature chambers at the Poway facility. Rapid temperature changes were used in our HALT and HASS equipment to determine the operating margin while the card was being used in a host. While the flash was rated for 0-70°C, it was able to start up and operate at temperatures 5-7° warmer than rated. This sort of slight margin is often the case when using new, major brand flash, and in some cases exceeding the specifications by more than 10% is normal. It was noted that once over 80°C the card would no longer operate.
HALT and HASS tests (Highly Accelerated Life Test and Highly Accelerated Stress Screen) are great methods of product testing to determine failure modes and root causes, functional operating limits and functional destruct limits of embedded storage cards. This “Failure to improve Reliability” allows a manufacturer to determine operating margins of products, and even better, to find the first link in the chain to break. For example a connector, CPU, flash chip or even some underlying component may be the first component to fail. This information helps manufacturers like Delkin to maximize ruggedness by replacing the “weakest link” as far as possible to increase the operating margin of its designs.
The problem with the Dashboard cameras was not the operating temperature, it was the storage temperatures. Storage temperatures are usually higher than operating temps, and justly so, as the circuit is not energized. In this case the host was soaking in a vehicle in the sun with the windows up for hours, failing product testing. The temperature inside that camera case was over 100°C (212°F) and the temperature would take some hours to reduce to the adjusted temperature in the car due to the AC being turned on by the occupants. The 100°C startup temperature was beyond the specifications of the MLC flash and it was unable to operate. The solution would need to be a better ventilated box, or switch to SLC flash. Another solution was some period of cooling off prior to powering up the dashboard camera.
You have to choose carefully when designing in an industrial storage solution for your embedded device. Besides finding one which meets your requirements for physical size, capacity, temperature, cost, functionality, and your usage model, you need to choose a standard that will still be supported for the lifetime of your product. Consumer-based standards come and go, so consult with Delkin to help you with product testing and make the right choice on an industrial embedded storage solution that will exceed the extreme requirements of your host device.
Lean on Delkin’s Technical Team
Have you had a problem with your host storage? The Delkin Customer Applications team stands at the ready to be your trusted advisor for your host critical storage. We have solved hundreds of complicated host failures and look forward to understanding your usage model for flash based Rugged Controlled Storage.
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