How to Correctly Choose Insulating Materials for Circuit Boards?
The panel must use insulating materials, which can be glass, polystyrene, polyvinyl chloride (PVC), nylon, resin glass, etc.
In the production process, to keep the material and thickness of the panel unchanged, the surface of the panel must be sprayed with insulating paint.
The thickness and material of the panel determine the sensitivity of the printed circuit board with the same electrodes.
For example, 3.2mm thick nylon (Nylon) is equivalent to 2.8mm thick Plexiglas.
Generally, when the thickness and area are the same, the greater the dielectric constant, the higher the sensitivity.
However, in normal applications, it is recommended to use materials with moderate dielectric constants, such as Plexiglas.
If the dielectric constant is too small, the sensitivity will be poor; if the dielectric constant is too large, the probability of malfunction will increase.
Layout: Place the CIN capacitors as close as possible to the IC, and the CIN capacitors of each channel must be grounded.
The induction plate should be as close as possible to the IC so that the connection between the induction plate and the IC will be the shortest. The layout should try to ensure that the distance from the touch IC to the sensor plate is basically balanced.
Printed Circuit Board Wiring
- The wiring from the sensor pad to the touch chip should be as short and thin as possible. If the PCB process allows it to use a line width of 5MIL.
- Do not cross other signal lines from the sensor panel to the touch IC. Especially can not cross strong interference, high-frequency signal line.
- Do not run other signal lines around 0.5mm from the sensor panel to the touch IC.
- If the copper foil pattern on which PCB is used as the touch sensor pad, try to use a double-sided PCB. The connection between the touch chip and the sensor pad to the IC pins should be placed on the back of the sensor pad copper foil (BOTTOM). The induction plate should be close to the touch panel.
- The touch IC and its related peripheral circuits should be laid with a 45° grid, and the copper area in the grid should not exceed 40% of the total area. Do not pave the ground 0.5MM around the connection. There must be a distance of at least 10mm between the induction plate and the floor. The backside of the sensor plate is not allowed to lay the ground, nor is there any large area of copper foil and other signal lines.