Pattern editor: How to cut out portion of a pad?

Making your own components and patterns, organizing and using libraries.
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bird
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Pattern editor: How to cut out portion of a pad?

#1 Post by bird » 17 Oct 2017, 21:51

When clearance needed by cutting out a portion of the pad - how to do that? If I get it right all the shapes tools in the pattern editor are for the silk layer, not to be used on the copper layer...
Attached is a picture of the oval pads which need clearance between them. How to make that cutout?
oval-pad-undercut.JPG
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Tomg
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Re: Pattern editor: How to cut out portion of a pad?

#2 Post by Tomg » 18 Oct 2017, 08:34

1) Create a drawing of the desired shape (units in millimeters) using your favorite 2D CAD program, making sure to add a narrow rectangular bump (1mm wide or less) extending 0.5mm horizontally from the center of the trimmed side. Include the bump's horizontal extension in your calculations when making the drawing symmetric about the (0,0) origin on the X-axis (see figure 1).
2) Save the new drawing as a DXF file to a convenient location (e.g. desktop).
3) In the Pattern Editor insert a new (blank) pattern into the desired pattern library, select Pattern in the Main Menu and choose Import from DXF... in the drop-down menu.
4) In the Open dialog window locate and select/highlight the new DXF file and click on the [Open] button.
5) In the Import DXF dialog window set DXF Units: Millimeters, Import Mode: Add, select the appropriate DXF layer and set Convert to: Top Signal, enable only the [x]Fill Closed Areas option and click on the [Import] button.
6) Back in the Design Area right-click on the outline of the imported object and choose Convert to Pad in the pop-up menu (see figure 2).
7) Double-click on the newly-created pad, select the [Type/Dimensions] tab in the Pad dialog window and set Type: to Through-Hole.
8) In the Hole section near the bottom of the Pad dialog window, set Shape: to Oval, Width: to 6 mm, Height: to 2 mm and select [OK]. You should now see something resembling figure 3.
9) Double-click on the pad again, select the [Type/Dimensions] tab in the Pad dialog window and click on the [Points...] button.
10) In the Polygon Points dialog window delete both of the bump's outside extents and select OK (see figure 4).
11) When the Pad dialog window returns to view, click on OK. The result should be a pad resembling figure 5.

I have included a DXF file named "pad_cutout.dxf" (inside the zip folder below) which was used in this example...
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Tom

bird
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Re: Pattern editor: How to cut out portion of a pad?

#3 Post by bird » 18 Oct 2017, 15:44

Thank you Tom, this is quite elaborate extensive process you've done to cut out a rectangular chunk from the pad (this task DT does rather simple in PCB layout when creating polygonal copper pour... why don't they do the same in a pattern making?). I appreciate learning from you about import of CAD-made DXF file into a new pattern.
But following your sequence failed at step #6 though. It did convert to a pad but without sticking out tab (you call it a bump) whence later while making a through-hole, it gets positioned shifted to the left from the center. The reason failing at step 6 is that outer two points of the tab are not highlighted showing that tab is not part of the newly converted pad and DT positioned a hole in the center between truncated outline (I think you made that tab only for the purpose to position a center hole - so without tab the hole is shifted). May be sticking out tab, when it was saved in CAD , was not saved in DXF as a part of outline? Or did not get imported as a complete outline?

I wish DT would make it simple to cut out rectangular piece from copper or , another approach, allow making elaborate polygonal copper pattern as they already have done in PCB layout... without need to use another large tool such as CAD....

On the second thought about using DXF file from CAD - can't we also make perforated plated holes (vias in PCB terms) in the pad using DXF file and choosing "convert to hole" when importing? 'cause this is another pain in the butt - currently I make fake pads to get those manually added plated holes for large pad cooling (see my image in the first post)... 36 fake "through-hole" pads to later deal with DCR errors! It is not clear though whether those "convert to holes" get plated or they are mounting holes (not plated)...
unfortunately currently there is no choice to make additional plated holes through the same pad ... a fast growing trend in PCB these days is metal substrate PCBs with many cooling perforated pads for power components ...
Thanks again
Vladimir

-- 18 Oct 2017, 15:50 --

Just when I clicked submit button , a thought came to me that it might be easy to add vias to a large pad like that in PCB layout instead of making those holes into a component pattern? ... (sorry , this is a side topic to this post necessitated by the same component pattern)

-- 18 Oct 2017, 15:57 --

no good - adding vias to a large pad in PCB layout is no good - moving a component around will leave it's holes in the old location ...oops:)

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KevinA
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Re: Pattern editor: How to cut out portion of a pad?

#4 Post by KevinA » 18 Oct 2017, 16:04

The TOMG file just got bigger:
edge.JPG
I was waiting on this answer since I couldn't figure out the inside hole dimensions with the information provided, the via thing stopped me too.
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Tomg
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Re: Pattern editor: How to cut out portion of a pad?

#5 Post by Tomg » 18 Oct 2017, 16:35

It works with the downloaded DXF file for me. Maybe I'm too close to it to see any errors I may have made. Yes, you can add vias in the PCB Layout editor, but not the Pattern Editor. Everyone has been asking for some sort of thermal via function to be added to the Pattern Editor, but so far nothing has come of it. Attached is a short video that demonstrates the procedure I outlined above...
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Tom

bird
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Re: Pattern editor: How to cut out portion of a pad?

#6 Post by bird » 18 Oct 2017, 19:59

I followed exactly your video - after conversion to TOP SIGNAL , right click does not select the tab part, whence it is not converted to a pad.
I understand how you do this, I can just make my DXF file like that in solidworks, but I still want to make it simpler ... with such a complex way implementing such a simple task, I'll never finish my project in this lifetime :)
We need to make a feature suggestion for simple copper cut in a pattern design and also for pattern of plated holes in a pad....
Thank you Tom for help

Tomg
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Re: Pattern editor: How to cut out portion of a pad?

#7 Post by Tomg » 18 Oct 2017, 20:13

bird wrote:"...right click does not select the tab part..."
Are you right-clicking on its outline (perimeter)?
Tom

bird
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Re: Pattern editor: How to cut out portion of a pad?

#8 Post by bird » 19 Oct 2017, 09:26

Yes, the outline, and it selects the main part without tab

-- 19 Oct 2017, 09:28 --

it is strange that zoom-in shows that the two points at the base of the tab are not joined so the closed area suppose to include the tab to be completely closed, but it does not

Tomg
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Re: Pattern editor: How to cut out portion of a pad?

#9 Post by Tomg » 19 Oct 2017, 11:27

Which version of DipTrace are you using? (I'm doing this in v3.1.0.1.) Did you enable the [X]Fill Closed Areas option? The imported object should be filled.
Tom

bird
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Re: Pattern editor: How to cut out portion of a pad?

#10 Post by bird » 20 Oct 2017, 22:31

Hi Tom, I am using 3.1.0.1 , Fill Closed Areas enabled, but the tab is not filled , only main area filled (though it is not enclosed without tab according to my inspection).
Something different is in the setup I guess... but peculiar thing about DT is that ... there is no usual setup :)

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