PCB-integrated flow sensors — How good is state of the art technology?

Printed circuit board technology is today well established and inexpensive, but achieves also remarkably high precision. This makes this technology interesting for the fabrication of sensors, especially when cost-effectiveness is a concern. However, since PCB technology is not actually optimized for this purpose, the question arises how reliable and repeatable the production processes are when it comes to producing acceptable quality. In this paper, we investigate calorimetric flow sensors for air conditioning monitoring, implemented by state of the art PCB technology. After demonstrating that such sensors can indeed work as expected, we examine the influence of process variations on the electrical parameters of the sensor. Using data from two different fabrication runs, we find that standard processes can yield sensor devices within a 10% tolerance range, which is sufficient for the target application.