Disassembly

Disassembly of the Roccat Isku+ Force FX is fairly simple once you realize there are several screws hidden under the various rubber pads on the back in addition to those visible and exposed. All the screws have a Phillips head, and a precision driver bit will help here. Once done, the bottom case panel separates from the rest of the keyboard. Turn the top piece around and remove the internal USB connector to remove the keyboard's cable. We now still have a collection of individual parts in the top piece that can be removed layer by layer.


Some of the ribbon cables you see here are held in place by pieces of tape, so carefully pry the taped pieces out and unscrew the three larger bare metal head screws holding the white plastic layer at the top in place. It can now be removed, which reveals that it helps with the backlighting for the majority of the keyboard. Having many other layers in between might hurt the backlighting's intensity, however, so this is something we will take a look at in due time. This also means that the subsequent layers have to be transparent or translucent at most, as is the case with the next layer that is a clear plastic sheet with a cutout around the pressure sensitive zone (Q/W/E/A/S/D keys). Now, we get to the signal-generating PCB (plastic sheet) which is in turn connected to daughter PCBs (hard boards), and some more screws need to be removed to get these daughter boards out of the assembly.


The PCBs are still connected, and I left them as such here to make sure I can still study them as-is later on. As expected, what is left now is the rubber dome sheet that provides the "switches" with the tactile feedback when bottomed out. The individual keys exist merely to provide a hard structure to move up and down, one it mates with the keycap as with just about any other membrane keyboard.


Taking a look at the daughter PCBs, we see simple buttons that are present under the keys assigned a specific use only - the media-control row, for instance. Similarly, there are dedicated LEDs on other daughter PCBs where the LED sheet would not work, and these are used in the top row at the left and right corners. The picture above with six LEDs does, for instance, correspond to the top-left corner wherein the first set of five LEDs help visualize activity in the pressure-sensitive zone, and the sixth is for the macro-recording button. The keyboard is powered by an NXP LPC1752FBD80 32-bit ARM Cortex-M3 microcontroller with up to 64 KB of onboard flash memory and 8 KB of SRAM. This is in addition to a dedicated Macronix MX25L4006E 512 KB flash memory module.


Going back to the primary PCB now, we see that there are actually two layers in some parts, especially around the pressure sensitive area. One of these layers has six special pads, which explains how Roccat has achieved the analog/force response modes advertised here. For some context, the Wooting One or Aimpad both use infrared switches of a sort with a sensor to detect how much the switch has traveled by, with this travel then translating into an analog motion as with joysticks on a controller. But here, the keystroke is only actuated when bottomed out since these are membrane switches, so Roccat has used a polymer-piezoelectric composite under these six switches.

The video, adapted from a product trailer, helps visualize what is going on here. The composite material under each of these six switches converts applied pressure into an electrical charge. As such, the higher the pressure applied to these pads as a result of pressure applied on the key after bottoming out, the higher the signal's charge that is then used to generate a pressure-sensitive response. The higher the range of pressure applied, the higher the range of analog/force response, which means the software driver has to be able to support this well.

Before we take a look at the driver, be advised that disassembly will void the warranty and that TechPowerUp is not liable for any damages incurred if you decided to go ahead and do so anyway.