The incorporation of capacitive touch technology into every day devices such as Apple’s iPhone and iPad has created an expectation for all other devices to follow suit. This new expectation is driving engineers and designers to integrate capacitive touch into their products. A great example of this is the exercise equipment manufactured by this client of ours.
Purchasing a capacitive touch design kits from IC manufacturers and trying to prototype your own design based on application notes is a large investment of time and money. Not only do you have to design the touch interface, but it needs to successfully pass ESD testing, radiated noise immunity test and conductive noise immunity tests required for consumer electronics such as a treadmill. This client quickly realized this and turned to us to help them give a modern look and feel to their product.
Not only did we help them design the prototypes for this client, but we were we were able to beat the foreign pricing and keep this a MADE IN AMERICA product.
One of the design recommendations is to let us characterize and configure the touch interface at its final resting place. This lets us identify issues outside the touch interface PCB that may impact the performance of the keyboard. This allows us to then strengthen the software filters, modify the layer stack up of our PCB or suggest modifications to the client PCB. In this particular example, the power section on the client’s main PCB was causing an extremely noisy environment for the 3 buttons directly above it. The noise being created by this power section was too much for our software filtering to handle by itself. So, we suggested a few modification to the customer’s main PCB.
There is a big difference between prototypes and production parts. These differences need to be addressed to ensure large manufacturing runs such as one required for this product is successful.
One of the differences is that we have to deal with variance in the overlay materials / stackup. Our custom touch firmware has tolerances built into it to deal with such changes.
Another difference is caused by the inks used to make the graphic overlay. We have tight process control checks in place to ensure that these inks do not contain conductive compounds/elements in them.
Last but not the least, the parasitics associated with a touch button itself may change from one PCB to the next. Depending on the method of capacitive touch used, there could be IC to IC variations that may affect the overall performance of the touch interface. Our firmware has the ability to calibrate itself from PCB to PCB to deal with such variances.
Also, by testing the assembled graphic overlay and the electronics together, we ensure a successful manufacturing run.
We are indeed a one stop capacitive touch design and manufacturing service.