How 3D Printed EMI Shielding Vents Solve Overheating and Electromagnetic Interference in Electronics

Through a novel method of manufacturing EMI vents using Additive Manufacturing (AM), we can address all these challenges by creating a single homogeneous part. By removing secondary operations, increasing vent performance, eliminating FOD risk, and facilitating design freedom, we can deliver a superior product with a shorter lead time.

Parker Chomerics is exploring manufacturing of vents through Additive Manufacturing and completed a preliminary performance comparison to traditionally manufactured vents. The vents were designed using a honeycomb cell size of 1/8” and thickness of 0.5”, with outer dimensions of 5” x 7”, which is representative of many parts that Parker Chomerics manufactures. Benchmark vents were manufactured from aluminum with electroless nickel plating and brass with tin-lead plating.

Our comparison between traditional and AM vents is focused on shielding effectiveness and air flow data, specifically between traditionally manufactured and Additively Manufactured aluminum vents, as well as between traditionally manufactured brass vents and Additively Manufactured Inconel vents.

Shielding effectiveness data was collected using the ASTM D4935 Standard over a frequency range of 800 MHz to 50 GHz (Figure 1a, b). Data was primarily analyzed in the “horizontal” orientations, which is the best-case shielding orientation. It was evident from the data that for both Inconel and Aluminum, vents maintained a high shielding effectiveness through 24 GHz. This is a significantly higher frequency than traditionally manufactured Brass and Aluminum vents, which drop off around 4 GHz (Figure 2a). It is also worth noting that, as hypothesized, shielding effectiveness of the AM vents behaved consistently regardless of directionality, whereas the traditional vents’ shielding effectiveness in the “vertical” orientation (worst case) dropped off around 2 GHz.

Air flow was also tested using a tabletop air flow tunnel (Figure 1c, d). AM vents performed better than traditionally manufactured vents, as indicated by a lower pressure drop across the vent for all wind speeds tested (Figure 2b). It is unclear how air flow may be affected at higher wind speeds, but with our ability to customize the cell sizes based on the required signal attenuation, we anticipate that cell sizes will be able to increase and air flow can be maximized.

An additional physical characteristic that will be relevant to the performance of the air vents is the weight, especially for enclosures on applications such as airplanes and helicopters. All 3D printed Inconel samples were significantly lighter than our benchmark brass vent, with the top performing Inconel vents ranging between 57.9% and 72.3% of the total weight of the brass benchmark. Aluminum AM vents were somewhat heavier than benchmark aluminum, weighing in approximately 16.5% heavier (Figure 2c). The AM parts were not fully optimized for SLS printing, and we believe that with further Design for Additive Manufacturing (DfAM) we can see even more reduction in weight.

This exploration into additively manufactured EMI vents lays the groundwork for the wide adoption of this processing capability in industries with stringent performance requirements. It is evident from the shielding and air flow testing that direct swapping of traditionally manufactured vents with AM vents leads to stronger functional performance. Combined with the reduction of FOD and weight, engineers who utilize EMI vents will experience significantly better product outcomes via AM. Additionally, they will have significantly greater opportunities for design iteration due to the reduced lead time.

Furthermore, AM opens significant design freedom for engineers. Since we no longer need to worry about those standard material sizes with Additive Manufacturing, we can better attenuate the cells to the precise shielding performance required. For example, in some cases we are able to utilize larger cells and increase air flow. We can also better serve our customers in designing custom sizes and shapes of vents to their enclosures, including non-flat parts and larger vent assemblies that require honeycomb in multiple areas.