for some reason copper pour always misses placing some thermal spokes to pads. I had these pads named ground and they show up on net check as ground. What causes the miss??
Have you looked in the text report which lists any issues found?
The usual reason for a copper spoke being missing is that it physically cannot be placed, i.e. the spoke track plus the rounded end will not fit without breaking a design rule. An example is when the copper pour area that spoke connects to is too narrow and the spoke will protrude into a clearance area.
Post a picture of the pad and surrounding copper pour area.
Thanks for that Boss. I do get a list of "missed thermal spokes" and the coordinates of them. But this is not helpful as it does not suggest any remedy.
I will try to insert a picture of the bottom layer only. The thin yellow lines show which pads are on the ground net. Is there anywhere I can read the design rules regarding thermal spokes (with examples if possible?
Hi Klaus. The missed thermal spokes list does not suggest a remedy, but it shows areas to investigate.
First run "Optimise" nets from Tools or CTRL+D short cut, this performs a thorough check and removes the air wires (yellow lines) that have been successfully tracked/completed.
I have tried to enlarge part of your image and have placed some comments on it below
The purple boxes show thermal connections that will be consider OK as they have two or more spokes.
The red box cannot be connected by two spokes, ie just one so that does not get connected as it is considered something for you to connect manually as one spoke is considered to be inadequate. You can correct this by clearing the pour and placing a short stub of track which should connect when you repeat the pour. In some cases involving high current work a component may have to be moved to achieve two or three spokes if the single spoke is not enough.
The two shown with blue boxes appear to be errors which I cannot explain as there appears to be plenty of room for the spokes. I suggest clearing the copper pour, performing the CTRL+D, then making the stub of track at the 1 K resistor and redoing the copper pour followed by CTRL+D again to see the outcome.
If as I suspect the error remains send your PRJ, SCH and PCB files to support using "submit a request" button at the top of the page. Post another picture here as well so we can see the final errors.
I couldn't see a description of spokes and copper pours so I can only assume help has changed or I learnt and read about this in the old web site. I have message support to suggest it is considered for a future FAQ.
Regarding the spoke size the whole length must be able to be placed on the board without encroaching on another pad, i.e. the spoke is only placed if the Design Rules can be obeyed. Here is part of a little test design I did.
I selected multiple spokes to highlight their size. The rounded end of the track as said must not encroach into any restricted space i.e. clearance settings, hence why some are placed at 45 degrees to achieve a successful pour.
After generating this I realised the air wires could add to the confusion (sorry). I had not done CTRL+D hence some remain that are completed. The pad pointed to by the purple arrow is not connected to the copper pour but the net pointed to (which I had not routed), so the air wire that appears to go through three pads pointed to by the green arrows actually only goes to the bottom and top of the three pads. Hence the importance of doing an "optime nets" which will remove this air wire and avoid confusion. Hope this helps a bit.
I went back to my test design to show the view after optimis nets, but left the above in the post to clarify the outcome..
Thanks Boss, excellent explanation. Yes, I was adding short track stumps to replace missing thermal spokes here and there on another board but wondered why that was required.
Also your explanation of 'air wires' is very timely, these had me forever confused. (I'm still on L plates with this program).
How did you manage the diagonal thermals? I had not thought about this solution. I have yet to figure out how to run tracks diagonally as well, I'm sure its just a simple trick?
Hi Klaus you are welcome, I've been using the program since V3 professionally and for personal use so have learnt a few bits!
I still don't know why the pad in the blue box didn't route correctly though and haven't managed to repeat that.
The diagonal thermals were automatically generated I don't think you can choose to generate them. The copper pour seems to be quite intelligent and works correctly most of the time. What seems to happen is it tries to put vertical and horizontal spokes in, if it can't place 4 it tries again with the diagonal spokes and leave in place the most it can position. The pad on R3 in my test design prevents the vertical spokes, but does not obstruct the diagonal ones so it leaves them in place.
One final snippet of info is the copper pour is 'painted' into the area as a continuous build of copper lines/tracks to fill the area and meet the design rules. This is why it should be done as the last operation. The line width used for the fill is the same as the line width of the boundary, so don't go too thin as you may get narrow lines of copper between pads and the manufacturer will charge a premium to reproduce those. Your copper fill looks OK though so this is just for information.
Regarding placing diagonal tracks when placing track you can select the "Segment Mode" by a right click. It remembers the last mode set, but you can change it whenever you want while placing the copper, look at "Segment Mode" in the help index.
I tend to use Orthogonal and Mitre for most of my designs.
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