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TIDA-00364: TIDA-00364 metal clad PCB for the power board

Pallab Sarkar34
Prodigy 210 points
Part Number: TIDA-00364

Hello,

As per the design document, TIDA-00364-PB PCB is a IMS PCB with 3mm board thickness, 2oz Copper thickness with immersion Gold surface finish.

I would like to know whether the operation of the inverter be affected if we go for MCPCB with 1.6 mm board thickness, 1 oz finished Copper weight and lead free HASL as surface finish for the TIDA-00364 PB PCB?

Thanks,

Pallab

  • 0
    TI__Expert 3685 points
    The inverter board has a very high output current rating. I suggest to go for 2 oz or higher.

    Using 1.6mm board thickness can cause the board to bend a bit at the center and the metal may not contact properly with the heat sink. You need to either use a thicker board or provide more screw holes to connect it firmly to the heat sink.

    Using lead free HASL finish is fine

    Regards,
    Pawan
  • 0 in reply to Pawan Nayak
    Prodigy 210 points
    Hello Pawan,

    Thanks a lot for sharing your views. Actually, we got to know that MCPCB with only1.6mm thickness and 1 oz copper can be designed by the sources that we tried to contact. It would be of great help if you could please suggest some alternate sources, where the PCB with the required specifications can be obtained.

    Regards,
    Pallab
  • 0 in reply to Pallab Sarkar34
    TI__Expert 3685 points
    Hi Pallab,

    I can help you with queries regarding TI devices. I do not have a ready alternate PCB manufacturer information, try searching for IMS PCB vendors on the web.

    Regards,
    Pawan
  • 0 in reply to Pawan Nayak
    Prodigy 210 points
    Hello Pawan,

    Thanks for your suggestions. I wanted to ask about the current ratings. Actually,the MOSFET can take 200A peak; when 5 are connected in parallel as mentioned in the document, maximum current rating is 200*5=1000A through each leg.

    The requirement by the motor is 130A RMS, implying a peak of 130*1.44=183.84A. Taking a factor of safety of 200%, the maximum current rating is 367A. I guess that the PCB is designed to handle 1000A whereas, the actual maximum rating is 400A( assuming, as said earlier). In that case, can 1oz (35micron) copper be insufficient to meet the demand, assuming that the copper thickness is decided based upon the current rating.

    Please correct me if I am wrong.

    Regards,
    Pallab
  • 0 in reply to Pallab Sarkar34
    TI__Expert 3685 points
    The MOSFET's are selected based on the total power loss and the junction temperature rise.

    The below video helps explain more about MOSFET current ratings.

    training.ti.com/understanding-mosfet-datasheets-current-ratings
  • 0 in reply to Pawan Nayak
    Prodigy 210 points
    Hi Pawan,

    Thanks for the sharing the information about the MOSFET ratings. I would request you to share some information on how the thickness of copper layer for IMSPCB is decided . Which current rating is responsible for the choice of the Copper thickness? Is it the maximum current that the inverter is designed for (400A) or the maximum current that the combined set of 5 parallel MOSFETS can handle (1000A)?

    Thanks,
    Pallab
  • 0 in reply to Pallab Sarkar34
    TI__Expert 3685 points
    The copper thickness was selected for nominal continuous current rating of upto 130Arms which is what the inverter was designed for. Calculation of copper thickness for IMS PCB is not straight forward and you might have to do a thermal simulation with an electronics thermal analysis software. You need to find the power dissipated in your PCB tracks and the temperature rise in the tracks should be within limits for the heat sinking setup you are using. The tracks should not fuse.

    In TIDA-00364 we have used a larger heat sink and not optimized its size, the goal of the design being showing paralleling of FET's and gate drive for parallel FETs. So finally you have to ensure that the temperature rise in tracks in your PCB design is within limits of what the PCB can handle. Please check with your vendor the maximum temperature the PCB material can handle.

    Regards,
    Pawan
  • 0 in reply to Pawan Nayak
    Prodigy 210 points

    Hello Pawan,

    Thanks for giving the insights on thermal analysis.

    Regards,

    Pallab