Salvage: Inside a Synaptics Touchpad

Passing by my regular salvage dump site, I managed to come across another laptop that was broken and thrown against a wall. The laptop in question was a Clevo T2V – not a glorious brand, as I’ve had heaps of trouble with them in the past, but was a resistive touch tablet-laptop hybrid machine.

So I lost most of the laptop – but I got to take the touchpad yet again! This time, it’s a Synaptics touchpad – and surprisingly, it looks different to the Alps Electric touchpad I took apart earlier.

SynapticsTP-Front

It took a bit to remove the plastic layer over the board (the grey plastic which your finger slides across). Then I had to contend with a heap of adhesive – which took a lot of time to rub-off. This touchpad is configured for a 4:3 aspect ratio as per the screen. The pitch between vertical sense lines are the same as for the Alps Electric touchpad, which is a bit of a surprise. Interestingly, the vertical sense lines seem to have been painted over to prevent any chance of shorting but this isn’t strictly necessary. The horizontal sense lines – as you can guess – run between the vias.

To confirm this, I shone a LED torch through the back of the touchpad PCB while scanning it underneath. Note how the black circled areas where there is a clearing of the diamond pattern with a dark line through it, implying the horizontal sense trace passes through in a layer inside the PCB. The yellow circled areas serve as reference where there is no horizontal sense trace in the area in a diamond pattern clearing.

Synaptics TP - HSense

SynapticsTP-Rear

And there’s the rear of the touchpad. Unfortunately, it’s a bit blurry due to the use of the CIS based LiDE scanner with a tiny depth of field.

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