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Maybe OT: Routing too close to an edge cut [message #8213] Wed, 20 January 2021 06:48 Go to next message
rcini is currently offline  rcini
Messages: 64
Registered: October 2015
Location: Long Island, NY
Member
All --

I would like to tap into everyone's collective experience with using KiCad and Freerouting to help solve a board routing issue. I've designed 4 or 5 ECB boards, and I've never had an issue with traces being too close to the edge cuts. I have another retro board I'm doing -- it's larger and fairly dense -- and I can't seem to find a way to force the traces back from the edge. I had 5 prototypes made, and PCBWAY had no issue making the boards, but the traces are very close to the edge. My understanding is that there is no real way in KiCad to increase just the edge clearance. The track clearance is the standard 7.87 mils.

How are the designers on the list dealing with this? I thought about adding a small keep-out area on the two long edges. I already tried the trick with widening the edge cut line (Freerouting routed inside the edge cut), and that didn't work. Anything else I should consider trying? If not, I can post this to the KiCad list and see what I get.

Thanks!

Rich


Rich Cini
Re: Maybe OT: Routing too close to an edge cut [message #8214 is a reply to message #8213] Wed, 20 January 2021 07:32 Go to previous messageGo to next message
wsm is currently offline  wsm
Messages: 232
Registered: February 2017
Location: AB, Canada
Senior Member
I realize this doesn't answer your KiCad question but may be useful for Eagle users. In Eagle under DRC (i.e. Design Rule Check) there is a "Distance" parameter for "Copper/Dimension" which sets the minimum edge distance including for copper pours. Although each board house may have unique minimums, I've been using 15mil for PCBWay which allows for LIGHT sanding to remove the sharp edges and haven't had any issues. It's hard to find on their website but they reference the SparkFun design rules which specify a minimum of 8mil edge distance.
Re: Maybe OT: Routing too close to an edge cut [message #8215 is a reply to message #8214] Wed, 20 January 2021 07:37 Go to previous messageGo to next message
rcini is currently offline  rcini
Messages: 64
Registered: October 2015
Location: Long Island, NY
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That's helpful. The distance parameter defaults to (rounded) 8 mils, so that's good. It seems to be a "bug" (or at least a missing feature) in KiCad which doesn't have its own autorouter (I use the old standalone freerouter). Maybe it's buried there in one of the design rules.

Rich Cini
Re: Maybe OT: Routing too close to an edge cut [message #8216 is a reply to message #8215] Thu, 21 January 2021 09:59 Go to previous messageGo to next message
guus.assmann is currently offline  guus.assmann
Messages: 50
Registered: May 2018
Location: Netherlands
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Hello,
One trick I can suggest: Place a trace along the edge yourself.
If it's a closed loop, it will not be (re)moved by the auto-router.
BR/
Guus

[Updated on: Thu, 21 January 2021 10:00]

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Re: Maybe OT: Routing too close to an edge cut [message #8222 is a reply to message #8213] Thu, 21 January 2021 23:51 Go to previous messageGo to next message
b1ackmai1er is currently offline  b1ackmai1er
Messages: 396
Registered: November 2017
Senior Member
Hi Rich,

Maybe keepout zones flow are understood by freerouting now, have you tried them?

Edit: You can define a keepout zone in freerouting using the right click context menu I think.

Is this any help?

https://kicad-users.yahoogroups.narkive.com/nm05UAwm/how-do- i-use-kicad-and-freeroute-to-keep-aireas-free-of-routing-und er-chips

tuddypat
11 years ago
Permalink
Hi,
Here is how I do it, using Freeroute.

In Kicad, with a copper plane selected as the working plane, use filled zones to mark the protected areas.

The filled zones should be connected to <no net>.

Once the board is finished, export to DSN

Edit the DSN using notepad..look for entries similar to this:

(plane @:no_net_0 (polygon Copper 0 8822.8 -5578.7 8822.8 -2940.9 6618.1 -2940.9 6618.1 -3019.7
8783.5 -3019.7 8783.5 -5578.7))
(plane @:no_net_0 (polygon Component 0 8822.8 -5578.7 8822.8 -2940.9 6618.1 -2940.9 6618.1 -3019.7
8783.5 -3019.7 8783.5 -5578.7))

(The above defines areas on the copper and component side opposite each other, other planes may be defined, all planes are independent.)

Edit the line to change 'plane @:no_net_0'
to keepout, for example:

(keepout (polygon Copper 0 8822.8 -5578.7 8822.8 -2940.9 6618.1 -2940.9 6618.1 -3019.7
8783.5 -3019.7 8783.5 -5578.7))

When imported to freeroute the required areas are protected.

You can do it in Freeroute but every time you change the board you need to redefine the keepout areas, I find doing it in kicad is much easier.

regards John

[Updated on: Fri, 22 January 2021 08:26]

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Re: Maybe OT: Routing too close to an edge cut [message #8224 is a reply to message #8222] Sat, 23 January 2021 07:29 Go to previous message
rcini is currently offline  rcini
Messages: 64
Registered: October 2015
Location: Long Island, NY
Member
Thanks. I put a 15 mil keep-out zone along the two long edges of the board where it gets "pinched" between IC sockets and an edge connector. Freeroute did respect the keep-out, so that seems to be the easy solution. Putting a fake trace is a good idea too. I didn't think of that.



Rich Cini
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