A while back, I posted a gripe article about how I disliked some aspects of the Secure Digital memory card format, one of the issues being the fragility of the plastic shell. Through no fault of my own, it seems it has happened to one of my largest cards. Damn.
My Kingston 128Gb card is the largest that I own today, and I tend to keep it safe and away from harm. This includes preferentially using smaller capacity cards to do the frequent back and forth dumps, as well as using plastic flash card cases to hold it.
As it turns out, the plastic case I was using was a little tight, and was “squeezing” the card along its ends. After a few inserts and removals, the halves of the case began to separate … and so we end up at this unintentional teardown.
The disassembly part of the teardown was taken care of by the tight plastic card “case”. Its pushing against the ends of the card led to the halves of the case separating – the case itself is only secured by a bead of adhesive around the perimeter. The positive of this is that the thin plastic casing was undamaged, unlike when such issues are caught too late, and thus a full repair is feasible.
The card itself mainly consists of three chips – two flash memory chips marked FA64B08UCT1-7C S1339-2603773. This marking seems to be only used on flash drive products from a Google search, and doesn’t reveal who the manufacturer of the flash is. As a result, it could even be lower quality flash, and or TLC flash from unknown parties. It seems it is likely manufactured week 39 of 2013 based on the laser-etch code. The third chip is a PS8035-0 controller from Phison.
The rear of the PCB, as expected, contains no components. The mould code can be seen in the rear segment.
A repair of a broken SD card is conceptually simple, but some care is required. For one, we shall be using superglue (aka cyanoacrylate). The key is to not apply too much, and to apply it precisely. You wouldn’t want to have to toss a card because you chose a bad $2 bottle of glue. For that reason, I did make a trip this week to Bunnings and picked up a Loctite branded “precision” 5g bottle of Superglue. This would be handy for other repairs as well.
I began first by applying four small drops of glue to the rear mold plastic so that the PCB can also form part of the “assembly” and hold the unit together. Then, I placed the PCB on top, and carefully pushed down evenly to spread the glue.
Then for the top-side, I decided to apply a thin bead of glue around 80% of the perimeter of the top side lid, and then apply a drop of glue on top of each of the flash chips so they can also participate in strengthening the card itself.
Carefully, I picked up the top lid by the edges, aligned it and then squeezed both parts together. It was satisfying that my fingers weren’t glued together, and only a tiny excess of glue can be seen at the seams. Some time was allowed for the glue to set, and then the repair is complete.
One relatively expensive card is fixed by a few dabs of glue from a premium bottle of superglue. The key is not to put too much glue, and to put it in the right places. Another big tip is to repair it as soon as it seems like it’s falling apart, so the case doesn’t break any further, otherwise a full repair could become impossible.