PCB isolation for SiC Modules

Fertmann

Hello,

I would like to find out what the specifications are for PCBs that are mounted on, for example, DC+, DC- and DC-Link.

I am particularly interested in the min. thickness of the insulation between the layers. According to IPC 2221B, the insulation should be 1.5mm at 1000V, for example.

I would be very pleased to receive an answer.

Forum_Moderator

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ChrisN

Hello Fertmann,

Thank you for your question. When possible, we always suggest adhering to published standards such as IPC 2221B for determining recommended creepage and clearance requirements. Following these standards will produce the highest success rate for reliable system operation. However, at elevated voltages (>500 V) these rating are often anecdotally considered conservative. For systems in laboratories and controlled environments (with proper safety precautions in place), we have successfully adopted the 300 V/mil layer-to-layer recommendation in FR4 material from the following reference:

R. Tarzwell and K. Bahl, "Design of High Voltage Printed Circuit Boards," in High Voltage Printed Circuit Design & Manufacturing, 1st ed. Sunnyvale, CA, USA: Sierra Proto Express, 2004, ch. 3, pp. 7-15.

Note that this approach results in ratings that are significantly less than the IPC ratings. These ratings should be considered an absolute minimum and may depend on the quality of the board manufacturer that you employ. Therefore these ratings should be evaluated on a case-by-case basis by the end user. In our applications, we typically adopt 3.2 mm thick circuit boards for our >2 layer PCBs in order to increase this thickness, even when the 300V/mil rating would be satisfied with a standard 1.6 mm thick board. This generally results in layer-to-layer spacings that are closer to the IPC rating.

Thanks,

Chris N.

TBhatia

Hi, I hope that this answered your question. I will close this discussion for now but if you have a follow up question, please "Start a New Discussion" and we would be glad to support you further.