+ Post New Thread
Results 1 to 4 of 4
  1. #1
    Newbie level 3
    Points: 46, Level: 1

    Join Date
    Jul 2018
    Posts
    3
    Helped
    0 / 0
    Points
    46
    Level
    1

    Dimension Thermal Relief Pad

    Hi all,
    I'm wrinting this post because I'm a bit confuse about dimension Thermal Relief Pad.
    I saw IPC 2221 and IPC 2222. I read Thermal Relief in Conductor Planes paragraph but I didn't understand some thinks.

    In the IPC thare is the calculation about total thermal width. (I think it is the total width of spokes ) but this number depends of the corrente max. And I dimension its as a tracks. What's the difference?
    I need to calculate air gap between pad and plane. How can I to get it?
    Thanks.
    Bye

    •   AltAdvertisment

        
       

  2. #2
    Advanced Member level 5
    Points: 12,264, Level: 26
    Achievements:
    7 years registered

    Join Date
    Feb 2010
    Location
    UNITED KINGDOM
    Posts
    1,938
    Helped
    606 / 606
    Points
    12,264
    Level
    26

    Re: Dimension Thermal Relief Pad

    Make it up....
    The width of the individual spokes theoretically should equal the required trace length to carry the current divided by the number of spokes...
    There is no air gap, only on the outer layers, just leave a spacing that is sensible (usually between 0.15mm and 0.35mm depending on the geometry of the components used and the board technology. Its just a thermal break, with the spokes carrying the current...

    •   AltAdvertisment

        
       

  3. #3
    Newbie level 3
    Points: 46, Level: 1

    Join Date
    Jul 2018
    Posts
    3
    Helped
    0 / 0
    Points
    46
    Level
    1

    Re: Dimension Thermal Relief Pad

    Thanks for your reply. I agree with you. I have to dimension the total width spokes in based the current.So the method In the IPC for me It is not complete. Normally i use an air gap of 0,5 mm for all. Why do you tell there is not air gap in inner layer ? For me there should be.

    •   AltAdvertisment

        
       

  4. #4
    Advanced Member level 5
    Points: 12,264, Level: 26
    Achievements:
    7 years registered

    Join Date
    Feb 2010
    Location
    UNITED KINGDOM
    Posts
    1,938
    Helped
    606 / 606
    Points
    12,264
    Level
    26

    Re: Dimension Thermal Relief Pad

    All inner layers are flooded with epoxy, therefore there is no air gap.... It is a gap between the pad and the copper of the power plane.

--[[ ]]--