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 Post subject: Annular ring pad with drill hole
PostPosted: 10 Jun 2017, 15:57 
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Joined: 10 Jun 2017, 15:44
Posts: 8
I'd like to create a pattern for the SMD microphone:

Invensense ICS-43434

Which has the footprint shown in the attached image (taken from the PDF above).

That footprint shows I need a ground pad that annular ring with a hole drilled through the center. This is different from a standard though hole pad, which has a copper plated hole. For the pad I need, the annular ring is bigger than the hole drilled through the center, and the hole to be unplated.

Is there a way to do this in DipTrace?

Brian


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 Post subject: Re: Annular ring pad with drill hole
PostPosted: 11 Jun 2017, 07:00 
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Joined: 20 Jun 2015, 14:39
Posts: 946
1) Create a drawing with the two needed concentric circles for the pad in your favorite 2D CAD program (or use the DipTrace PCB Layout editor) and save as a DXF file.
2) Import the DXF file into the Pattern Editor using the following settings: DXF Units: (same as DXF file units), Import Mode: Add, Convert to: Top Signal, enable the [X] Fill Closed Areas and [X] Embedded Polygons options.
3) Right-click on the outline of the imported donut shape and select Convert to Pad in the pop-up menu.
4) Renumber the new donut-shaped SMD pad if necessary.
5) Place a mounting hole of the desired diameter inside the donut-shaped SMD pad.
When creating the hole, note that page 17 of the datasheet states "...A minimum diameter of 0.5mm is recommended...". If you don't mind a plated through hole, you could use a normal through-hole pad with the proper hole and ring size instead of making the donut-shaped SMD pad.

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Tom


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 Post subject: Re: Annular ring pad with drill hole
PostPosted: 12 Jun 2017, 09:08 
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Joined: 10 Jun 2017, 15:44
Posts: 8
Thanks!

I tried this - and I can see that this would work - however, I have a few issues...

1) I use Inkscape, and using my defaults, exporting to a DXF and then importing showed no image on any layer. I tried a random DXF icon I found on the web, and it works fine - so it's clearly a Inkscape problem that I can look into.

2) The connection point of the pad appears to always be in the center of the pad based on the pad's maximum width and height. This is an issue when their is a void in the center of the pad, because layout will still try to connect copper to the voided center. Can I move the connection point?

3) Better yet, can I have multiple connection points?

Any thoughts (in particular on 2 & 3)?

Thanks again!

Brian


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 Post subject: Re: Annular ring pad with drill hole
PostPosted: 12 Jun 2017, 10:34 
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Joined: 20 Jun 2015, 14:39
Posts: 946
bri wrote:
"...I use Inkscape, and using my defaults, exporting to a DXF and then importing showed no image on any layer. I tried a random DXF icon I found on the web, and it works fine - so it's clearly a Inkscape problem that I can look into..."
If you don't feel like messing around with other programs right away, try drawing two empty, concentric circles in the PCB Layout editor and export the drawing as a DXF file.

bri wrote:
"...The connection point of the pad appears to always be in the center of the pad based on the pad's maximum width and height..."
Actually, it should be on an edge of the donut pad somewhere. Select the largest grid size (make sure there are no grid points inside or on the donut pad) and route a trace starting on the donut pad's perimeter to see where it attaches itself (i.e. the "origin"). For me it was on the right edge near the 3 o'clock position. It may be different for you.

bri wrote:
"...Can I move the connection point?..."
I think it is possible for polygonal pads, but the method is a little involved. Give the following a try...
1) Open the pattern in the Pattern Editor, right-click on the donut pad, choose Properties... in the drop-down menu, select the [Type/Dimensions] tab and click on the [Points...] button.
2) In the Polygon Points dialog window, click on the first set of coordinates (#1) in the points list and watch the donut pad in the dialog window's display. A red "X" will show the physical location of the coordinates. I believe the first point (#1) is always the "origin" for a polygonal pad (could be wrong, of course). Try editing the points list to see if you can move the "origin" to a location that suits you (e.g. inside the fill). Once moved, two more points will need to be added to the list (with coordinates identical to the original point #1) to keep the drawing shape intact; one at the very bottom and the other inserted right after point #1.

bri wrote:
"... Better yet, can I have multiple connection points?..."
Not to my knowledge.

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Tom


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 Post subject: Re: Annular ring pad with drill hole
PostPosted: 12 Jun 2017, 16:39 
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Joined: 10 Jun 2017, 15:44
Posts: 8
Okay, yes - I am seeing that (the connection point is on the side). I thought it was in the center because I routed a trace across the whole part, and the trace disappeared in the center where there's a drill hole.

Thanks agin,

Brian


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