A touch sensor panel is disclosed. In some examples, the touch sensor panel includes a substrate including a first side and a second side, a passivation layer, a first plurality of touch electrodes formed on the first side of the substrate, and a second plurality of touch electrodes formed on the second side of the substrate. In some examples, a component of the touch sensor panel, other than the first plurality of touch electrodes and the second plurality of touch electrodes, is configured to prevent light configured to activate the passivation layer during fabrication of the touch sensor panel from being transmitted from the first side of the substrate to the second side of the substrate.