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How to create library part with thermal pad?

Former Member

Hi there,

 

I was hoping someone could give me the recommended flow for creating a

library package with a thermal pad.  I'm using an LME49600TS/NOPBLME49600TS/NOPB which has 5

pins and a thermal pad.  The pad is electrically connected internally

to Vee.

 

I initially tried just marking a tStop region in the shape of the pad

hoping that if I just drew a polygon over it in the layout editor and

hit ratsnest, all would work out.  All I got was a polygon around the

pad not connected to it.

 

I then tried to draw a polygon in the package and name it something but

I discovered you can't name polygons.  A square pad would work I guess

but this isn't the shape of the pad which is in the shape of a 'T'.

 

Any pointers on the correct way of doing this?  The demo board doesn't

have the pad polygon connected to the Vee pin so that shouldn't be an

issue.

 

Thanks, Shareef.

 

 

Parents

  • I am also having this problem. I cannot name my polygon to the name I want!

    If I try to do this, the end result is the dialog window where you write

    the name just dissappears after you click on the polygon edge, and the

    polygon remains the same. It's very strange in the layout editor, I can

    name my polygo whatever I need, but in the component editor, it simply

    ignores my NAME request!

     

    In modern lingo : What's up with that y'all?

     

    or eighties version: Bummer dude, this polygon is having, like, an identity

    crisis, or like, identiphobia?

    --

    Web access to CadSoft support forums at www.eaglecentral.ca.  Where the CadSoft EAGLE community meets.

     

Reply

  • I am also having this problem. I cannot name my polygon to the name I want!

    If I try to do this, the end result is the dialog window where you write

    the name just dissappears after you click on the polygon edge, and the

    polygon remains the same. It's very strange in the layout editor, I can

    name my polygo whatever I need, but in the component editor, it simply

    ignores my NAME request!

     

    In modern lingo : What's up with that y'all?

     

    or eighties version: Bummer dude, this polygon is having, like, an identity

    crisis, or like, identiphobia?

    --

    Web access to CadSoft support forums at www.eaglecentral.ca.  Where the CadSoft EAGLE community meets.

     

Children
  • in reply to Former Member

    Redcutlass wrote on Tue, 29 March 2011 13:13

    but in the component editor, it simply ignores my NAME request!

     

    I think you mean the package editor?

     

    It would be nice if you could draw arbitrary stuff and have that be part of

    a pad such that the DRC doesn't create a flood of errors.  However, you

    can't.  Any time you want a connection point you have to start with a pad.

    You can then add copper to it as you like.  That will result in the right

    copper, but the DRC will give you lots of overlap errors.

    --

    Web access to CadSoft support forums at www.eaglecentral.ca.  Where the CadSoft EAGLE community meets.

     

  • in reply to Former Member

    Olin wrote on Tue, 29 March 2011 13:46

    Redcutlass wrote on Tue, 29 March 2011 13:13

    but in the component editor, it simply ignores my NAME request!

     

    I think you mean the package editor?

     

    That will result in the right copper, but the DRC will give you lots

    of overlap errors.

     

     

     

    Yes, sorry, I meant package editor.

     

    Actually that seems to be exactly the problem: Even if I place a pad, the

    copper ploygon I place around it, to mold to the shape I desire, does not

    "connect" to the polygon. I wish I could explain it better... When I fill

    my layout with ratsnest, it just goes all over the GND area, totally

    ignoring the tStop layer I made for it. IsnT' that what the tStop (or

    bStop) layer does? At least, that's how the SMD pads are treated...

     

    thanks!

    --

    Web access to CadSoft support forums at www.eaglecentral.ca.  Where the CadSoft EAGLE community meets.

     

  • in reply to Former Member

    Redcutlass wrote on Tue, 29 March 2011 15:42

    Actually that seems to be exactly the problem: Even if I place a pad,

    the copper ploygon I place around it,

     

    That makes no sense.  If you place another copper polygon completely over a

    pad, of course you won't get thermals.  The pad itself will generate copper

    gaps for the thermals, but your explicit polygon will put copper there

    anyway.

     

    Quote:

    IsnT' that what the tStop (or bStop) layer does?

     

    It's not clear what you think they are supposed to do.  The layers are well

    documented in the help.  Things drawn in the tStop and bStop layers make

    holes in the top and bottom solder mask, respectively.  I can't even guess

    why you think this has anything to do with thermals.  You really need to

    read the help for layers.

     

    --

    Web access to CadSoft support forums at www.eaglecentral.ca.  Where the CadSoft EAGLE community meets.

     

  • in reply to Former Member

    Actually I don't understand why you say it generates holes...

    I might need to read the help section on tStop, but I know that there were

    no holes generated in our boards on the tStop layer...

     

    I looked in the pdf Manual and they donT' mention much detail about the t

    and b Stop layers...

    --

    Web access to CadSoft support forums at www.eaglecentral.ca.  Where the CadSoft EAGLE community meets.

     

  • in reply to Former Member

    On 3/29/2011 3:10 PM, Owen wrote:

    Actually I don't understand why you say it generates holes...

    I might need to read the help section on tStop, but I know that there were

    no holes generated in our boards on the tStop layer...

     

    I looked in the pdf Manual and they donT' mention much detail about the t

    and b Stop layers...

    maybe you are confusing *Stop ( negative solder mask) with *Restrict (

    negative copper in fills) ???

     

  • in reply to Former Member

    On Tue, 29 Mar 2011, Owen wrote to us saying :

    >Actually I don't understand why you say it generates holes...

    >I might need to read the help section on tStop, but I know that there were

    >no holes generated in our boards on the tStop layer...

     

    Try reading what he said:

     

    >Things drawn in the tStop and bStop layers make

    >holes in the top and bottom solder mask, respectively.

     

    So there's no mention of holes in the board, nor of holes "generated in

    the tStop layer". It's quite simple, so let's try fewer syllables:

     

    The tStop and bStop layers define where the SOLDER MASK is NOT present.

    That is, they define the HOLES in the SOLDER MASK. Please note that this

    is the SOLDER MASK. It has ABSOLUTELY NOTHING to do with board holes or

    copper traces.

     

    If you want to keep a polygon (or the autorouter) away from somewhere,

    you need the tRestrict layer. This is all explained in the help, so

    perhaps you should read it.

    --

    Rob Pearce                       http://www.bdt-home.demon.co.uk

     

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