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Polygon and Thermals issue

nikoly

Good Morning,

I have a 2 Layers PCB and I have to design a polygon (as the datasheet suggest) which surrounds three devices pad as you can see in the attached file (red rectangle).

 

I wonder if I can  set on the thermals without losing the benefits of polygon (as you can see the attached file ).

 

Setting on the thermals will give me an help for hand soldering but my fear is that I should lose the benefits of the polygon.

 

Sorry for this dummy question but I'm not an HW expert.

 

Hope you can help

Thanks a lotù

Nico

image

  • On 3/10/2016 7:34 p.m., nikk kik wrote:

    Good Morning,

    I have a 2 Layers PCB and I have to design a polygon (as the datasheet suggest) which surrounds three devices pad as you can see in the attached file (red rectangle).

     

    I wonder if I can  set on the thermals without losing the benefits of polygon (as you can see the attached file ).

     

    Setting on the thermals will give me an help for hand soldering but my fear is that I should lose the benefits of the polygon.

     

    Sorry for this dummy question but I'm not an HW expert.

     

    Hope you can help

    Thanks a lotù

    Nico

     

     

     

    How about providing a link to the data sheet so we can know what you are

    dealing with.

     

  • On 03.10.2016 08:34, nikk kik wrote:

    Good Morning,

    I have a 2 Layers PCB and I have to design a polygon (as the datasheet suggest) which surrounds three devices pad as you can see in the attached file (red rectangle).

     

    I wonder if I can  set on the thermals without losing the benefits of polygon (as you can see the attached file ).

     

    Yes thermals has some impact, but the effect is most likely negible. The

    resistance in the short thermal stubs are a small fraction compared to

    the full polygon. If there are 100's of amps peak, a few nanoohm may

    cause a non critical difference. Make sure the polygon wire is wide

    enough (looks ok on the img). You don't want very thin wires there.

     

    Note:This looks like a switch mode power supply circuit, and it looks

    like pin 5,6,7 should be connected with pin8? They seem to be missing.

    Make sure the pin to pad mapping in the device is the type that must

    connect all pins. Using only one of the pins will make a huge impact!

     

    Setting on the thermals will give me an help for hand soldering but my fear is that I should lose the benefits of the polygon.

     

    Wild guess, but you will probably get 99 of the 100% effect by doing

    this, wich is fine.

     

     

  • Ok Guys,

    Thanks a lot for the quick answer .This is the device http://cds.linear.com/docs/en/datasheet/3759fc.pdf .

    I should leave thermals on in order to solder it by hand.

    Morten thanks for the advice about all disconnected pad (there are surely some mistakes) but it was just for example.

    Thanks a lot