Does the lack of feedthrough capacitors in the high-frequency filter capacitors of the BMS control board lead to a decrease in shielding effectiveness?

Yes, when filter capacitors are needed on shielded enclosures to filter high-frequency noise from conductors passing through them, using ordinary capacitors instead of feedthrough capacitors will severely degrade shielding effectiveness. The lead inductance of ordinary capacitors will resonate with the capacitor at high frequencies, causing it to lose its filtering function. Furthermore, these leads can disrupt the integrity of the shielding, becoming antennas for radiating or receiving high-frequency signals. Feedthrough capacitors, due to their unique structure, have their ground terminal directly connected to the shielding shell, with almost no lead inductance. They can effectively filter GHz-level high-frequency noise while maintaining the continuity of the shielding. Therefore, feedthrough capacitors are the preferred choice for filtering incoming and outgoing wires within shielded enclosures.