Problem doing thermals. They get swallowed by the Cu pour.

On 13/01/17 16:20, Benjamin Spenger wrote:

Dear Mr. Garcia

 

Today I gave my first ever Gerber files to print. I made those files with EAGLE. However my PCB has no copper pour as I failed to do the thermals right.

I can show my problem in a simple example work flow:

1. In eagle I choose New/Board

2. I make a via somewhere

3. With the “Name tool” I call it GND

4. I surround it with the “Polygon tool” (thermals enabled, width 0.016 mm)

5. With the “Name tool” I call the polygon GND

6. With “Ratsnest” I fill the polygon

This will swallow the via into the copper pour. However I would have expected to have the via somewhat thermally isolated with “thermals”.

Do you know what I am doing wrong? Googling it didn’t solve my issue. I read that it might have something to do with the pin tool. However the pin tool is supposed to be only in the schematic view and not in the board view…

 

(Not Jorge here - E14's "ask an expert" simply posts to a forum)

Actually the behaviour you see is correct. Thermals are required so that

the pad you are attempting to solder a component lead to can get hot

without all the heat escaping to the ground plane. Vias are not pads,

they are not expected to have component leads in them, and should never

need to be soldered. Therefore, they don't get thermals.

Are you attempting to use the via for something other than a via? Should

you be using a pad instead? Or is your concern over the lack of thermals

around it misplaced?

Cheers,

Rob

On 14/01/2017 5:20 a.m., Benjamin Spenger wrote:

Dear Mr. Garcia

 

Today I gave my first ever Gerber files to print. I made those files with EAGLE. However my PCB has no copper pour as I failed to do the thermals right.

I can show my problem in a simple example work flow:

1. In eagle I choose New/Board

2. I make a via somewhere

3. With the “Name tool” I call it GND

4. I surround it with the “Polygon tool” (thermals enabled, width 0.016 mm)

5. With the “Name tool” I call the polygon GND

6. With “Ratsnest” I fill the polygon

This will swallow the via into the copper pour. However I would have expected to have the via somewhat thermally isolated with “thermals”.

Do you know what I am doing wrong? Googling it didn’t solve my issue. I read that it might have something to do with the pin tool. However the pin tool is supposed to be only in the schematic view and not in the board view…

 

With kind regards

Benjamin

 

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Hi Benjamin

Thanks for a good description of your steps.

You can get what you expect. There is a setting in the DRC settings that

will give you thermals at vias.

DRC > Supply > Generate thermals for vias

Normally, for commercially made boards, you would not need thermals for

vias as there is no soldering at a via. For home made boards where you

are soldering a wire through the board of the non plated holes they

could be useful.

Forget Google as your first point of call. Use the HELP

Had you opened HELP and entered 'thermal' you would have discovered the

above  information.

Had you opened the user manual in the 'documentation folder and

entered 'thermal' you would have discovered the above  information.

HTH

Warren

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Dear Rob

Thanks a lot for your explenations. Yes, you are correct. I should have used pads instead. I will see how the PCBs turned out when they come. Probably I will do them over with pad now that I know :-)

Dear Warren

Thanks for showing me how to to use thermals on vias. But you and Rob are right: I should have used pads. But thanks to your description I could still use thermals on vias if I would need to do so in the future. For now I redesign the board with pads instead :-)

With kind regards

Benjamin