What’s Really Inside Your MicroSD Card?

Ever bought an item from a retailer, opened it up and thought something suspicious was going on? Well, in the case of some microSD cards, that something was possibly the result of Ghost Shift Workers, running machines after hours and flogging the parts on to distributors. Some of these cards found themselves in the hands of Andrew Huang, co-creator of the do-all multifunction device, Chumby. As Huang put on his investigative hat, he went down the rabbit hole into the shady world of corner-shop re-branding and OEM’s.

After noting that production yields of their Chumby One device had fallen sharply, some investigation brought to light that a batch of microSD cards from Kingston with similar lot codes seemed to be at fault. Normally they would be returned under RMA with replacements sent, however, since the cards had been programmed, Kingston refused. Due to the number of defective units being in the thousands, Huang decided to dig deeper. After a comparison between the faulty cards to his working stock, a few discrepancies were found.

Digging further with some help from Linux, the ID data was read and then compared. The two noteworthy points were that the irregular card were dated to 00/2000, so it had no date set, and its serial number decimal conversion was in the thousands, not the usual millions of units, both of which are tell-tale signs of ghost shift production (Workers do short runs ‘out of hours’, usually with inferior quality items). Huang then confronted Kingston with this evidence to which they replied that the items were not fakes but decided to offer an exchange on the programmed cards for new ones.

Intrigued by this, Huang delved even further into the issue and went around some of the gray markets, purchasing a variety of real and fake cards for comparison. Some of the sellers go insofar as to re-brand the cards right there and then in front of you, packaging, holograms, certificates and all.

To say this is isolated to Kingston would be unfair, companies like Sandisk and others would be at just as much risk as well. These out of hour’s production runs find their way to distributors and then into both consumer products and hands, with people being none the wiser to the fact that they could indeed be of an inferior quality, but marked as the real deal, damaging the companies reputation. If I dug through some of my own memory cards, maybe I’ll be in for a surprise. It would be interesting to see how many of these have ended up in people’s hands.

Overall, the MicroSD card market is a fascinating one, a discussion perhaps worth a blog post on its own. I’d like to point out to casual readers that the spot price of MicroSD cards is nearly identical to the spot price of the very same NAND FLASH chips used on the inside. In other words, the extra controller IC inside the microSD card is sold to you “for free”.