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Reference design of CRD-30DD12N-K: the layer stackup of the main PCB

gkim
gkim Contributor Level 3
edited December 2022 in General

Hello,

With respect to the reference design of CRD-30DD12N-K, we are going to build the main board by using the PCB design file of MAIN-0816A.brd.

With respect to the reference layer stackup of the main PCB, I have found out that the prepreg thickneess is 22 mils (0.56mm) and the core thickness is also 22 mils (0.56mm).

Meanwhile our PCB manufacturer employs the prepreg thickness of 0.3mm and the core thickness of 1.1mm.

Would it be fine if the main PCB is manufactured with the the prepreg thickness of 0.3mm and the core thickness of 1.1mm?

Thank you for your consideration.

With regards,

GKIM

Comments

  • FrankWei
    FrankWei Wolfspeed Employee - Contributor Level 2

    Hi GKIM,

    with different thickness of the prepreg and core, the parasitic capacitance between the traces will be different. if you are going to have thickness of 0.3mm for prepreg and the core thickness of 1.1mm, that parasitic caps between layer 1 and 2, and the cap between layer 3 and 4 will increase while the cap between layer 2 and 3 will decrese.

    I think the converter will still work. but not sure on the impact on the performance. thanks

    Regards,

    Frank

  • gkim
    gkim Contributor Level 3

    Hi FrankWei,

    Thank you for your review.

    Let me address the four layer PCB stack recommended in the datasheet for the isolated gate driver UCC5350MC.

    In Section 13.3 PCB Material of the datasheet, the thickness for the top and bottom prepreg is 10 mils and the thickness for the core is 40 mils with respect to the recommended layer stack.

    Are there any reasons that the main PCB for this reference design uses 22 mils thickness for the prepreg and also 22mils thickness for the core differently from the recommended layer stack for UCC5350MC?

    Thank you for your consideration.

    With regards,

    GKIM

  • FrankWei
    FrankWei Wolfspeed Employee - Contributor Level 2

    Hi GKIM,

    Yes, there are many components and circuits on the PCB. it is a trade-off to make a overall solution. there are cons and pros with thick or thin prepreg. you can compare the parasitic capacitors in your design (between the two solutions) then make the judgement. thank you.

    Regards,

    Frank

This discussion has been closed.