How can the ventilation holes of an HMI (Human Machine Interface) also provide shielding and heat dissipation?

When designing HMI heat dissipation holes, it is necessary to balance electromagnetic shielding and heat dissipation efficiency. Waveguide arrays or honeycomb arrays are commonly used. Waveguide arrays consist of a dense arrangement of many hexagonal or circular holes, each hole acting as a cutoff waveguide, effectively attenuating electromagnetic waves with frequencies higher than its cutoff frequency. During design, the size of a single hole is determined by the highest frequency to be shielded; smaller hole diameters result in higher cutoff frequencies and better shielding effectiveness, but at the cost of reduced ventilation. Honeycomb arrays, composed of many continuous hexagonal holes resembling a honeycomb, offer superior shielding effectiveness compared to circular arrays of the same diameter.

Another approach is to use metal mesh to cover larger heat dissipation holes; higher mesh counts result in better shielding but also increase airflow resistance. In actual products, heat dissipation holes are often placed on the sides of the equipment or in non-primary radiation/interference directions. Shielded heat sinks can also be used, with internal tortuous ventilation channels to increase electromagnetic wave attenuation. The design must balance shielding effectiveness, ventilation, and cost, and be verified through simulation or testing. Eintech offers standard or custom shielded ventilation window assemblies that integrate waveguides or cellular structures for easy integration into HMI products, achieving the optimal balance between shielding and heat dissipation.