| USB Flash Drive Demonstration at 30KV |
ESD protection in flash drive memory modules and mini-MP3 players rely primarily on overall system architecture and on-chip surge protection. These products can be highly vulnerable to latent ESD damage that builds up over time. This exposure is of greater concern in higher end drives and comparable high value-add products such as MP3 players. Field failure not only reflects negatively upon the quality of the brand but can also cost the manufacturer revenue in returned and replacement products – as well as time and resources in analyzing and confirming the root cause of the failure.
Using air and contact discharge methods cited in the EN 61000-4-2 and IEC 1000-4-2 standards, we have found that many USB flash memory drives fail between 12KV-16.5KV when applied with a discharge mode to the LED (predominant failure point) or seam (secondary failure point). A PASS requires that the product can continue to read, write and operate in standby conditions as each discharge mode is applied. |
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| Air (left) and Contact (right) discharge modes applied to a USB flash drive on a grounded bench. |
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The considerable increase in the window of protection for a USB Flash Drive, and |
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The straightforward manufacturability and implementation of XStatic™ materials, |
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we modified a drive design that supported a 256MB through 4GB product line and enhanced it with our VSD™ polymer nano-composite material for proof-of-concept assessment. For this particular application, the material was specified to provide a 400 volt minimum clamping voltage across the product line.
The drives were tested in accordance with the aforementioned standards and were all found to read, write and operate in standby conditions after application of each discharge mode to the LED and seam areas (and tested under both polarities). |
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Figure of a 30KV air discharge mode applied to a USB flash drive enhanced with the XStatic™-100 formulation. XStatic™-100 is an example of a Voltage Switchable Dielectric™ material. This product has been redesigned to provide 100% global protection against ESD events for each component on the circuit board. |
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| Exploring Limits through a Non-Standard Test |
| In order to promote failure of the flash drive module, the casing was removed and the open drive was subjected to repeated 30KV air and contact discharges at each polarity pursuant to the EN 61000-4-2 standard. The enhanced drives continue to function. In fact, it is currently not known how high an applied voltage the product will withstand as we are presently constrained by the limits of our ESD gun! A large number of “enhanced” drives have been tested and not one failure has occurred to-date. Moreover, we have performed this test on our “demo” drive at least five times at 30KV and it continues to function properly, preserving and accessing all files. |
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Click on the video to the left to view a 30KV air discharge emitted directly onto the unprotected circuit board of a USB flash memory drive that contains the VSD™ polymer nano- composite material. The spark can be observed to travel from the ESD gun through the populated board and out the USB connector shield as the voltage discharges to the grounded copper bench. The drive continues to function after each test.
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