Pseudo 2-lead component that has a trace between pads

Making your own components and patterns, organizing and using libraries.
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tinker1
Posts: 126
Joined: 19 Jul 2010, 16:33

Pseudo 2-lead component that has a trace between pads

#1 Post by tinker1 » 19 Jul 2010, 16:48

I am getting pretty good with the component editor, but that is largely due to the cool pattern and component editors. I made the "component" I want, but it does not totally do what I want.

The part is a pseudo 2-lead component that just has a trace in the top signal layer that goes between two tiny pads. It represents a jumper that could be cut in the event I want to modify the board with a blade. I can get it to appear on the schematic, and also on the PCB. However the PCB Layout design rules worry that my spacings between nets are not acceptable. It will not autoroute, and keeps showing the error each time I check design rules.

I know I can hand -route the missing traces. I know I could make a part like a tiny surface mount resistor and hand-draw the trace to be potentially cut manually, or I could combine nets after making the placements.

I thought there might be another way. An inductor made with a spiral pattern on the board would have a similar need. I can imagine that joining digital and analog grounds at a single place on a board would have a similar need.

Thanks.

Alex
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Joined: 14 Jun 2010, 06:43

Re: Pseudo 2-lead component that has a trace between pads

#2 Post by Alex » 22 Jul 2010, 04:32

You can create component with internal connection between pads. When you attach pattern in Component editor, left click on first pad and click on second one. It will create internal connection.
If you use that component, blue connection lines between pads will appear on PCB Layout. Autorouter and DRC will work correct.

tinker1
Posts: 126
Joined: 19 Jul 2010, 16:33

Re: Pseudo 2-lead component that has a trace between pads

#3 Post by tinker1 » 22 Jul 2010, 14:36

I just tried that. On my first try on my "cuttable jumper", my two pads in the pattern were tiny, so I could not see what was going on. So I made a big pattern with two bigger pads one above the other. Using this pattern I could see that I had added a red line between the two pads. Cool.

I put that component into a schematic. Looked good. Each side of the cuttable jumper was on a separate net.

But when I made a board (convert to PCB) with that component connected across two pins of a connector component, both terminals of each cuttable jumper had been converted to be on the same net. PCB Layout showed a blue line between the two pins of my connector, a single blue line to one pad of the cuttable jumper component, and another blue line to the other pad of the cuttable jumper component. When routed, I similarly had a single trace to the cuttable jumper component that continued on to the other terminal of that component.

Alex
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Joined: 14 Jun 2010, 06:43

Re: Pseudo 2-lead component that has a trace between pads

#4 Post by Alex » 23 Jul 2010, 08:58

If two pads connected together on layout, they will be joined in the same net. This seems logically.

pin
Posts: 4
Joined: 14 Jun 2010, 08:01

Re: Pseudo 2-lead component that has a trace between pads

#5 Post by pin » 30 Jul 2010, 17:48

This seems logical as long as the two pads remain interconnected. If that connection is to be manually cut on the final board, two independent nets will arise. So, if I understand the question, heart of the matter is how to design routing of certain net, consisting of two strictly separated subnets and joined with a "jumper" component. ???

tinker1
Posts: 126
Joined: 19 Jul 2010, 16:33

Re: Pseudo 2-lead component that has a trace between pads

#6 Post by tinker1 » 30 Jul 2010, 18:02

pin wrote:This seems logical as long as the two pads remain interconnected. If that connection is to be manually cut on the final board, two independent nets will arise. So, if I understand the question, heart of the matter is how to design routing of certain net, consisting of two strictly separated subnets and joined with a "jumper" component. ???
Yes. I know how to accomplish it. One way is to use a not-connected component during intitial routing, and add a trace later. I was hoping that I could just make a component to do the job that would not require remembering to go back for a later pass.

A related question would be how to design a 2-lead component, such as an inductor, antenna, fusible link, etc, that is formed with circuit traces. See http://www.diptrace.com/forum/viewtopic.php?f=4&t=87 for an example.

pin
Posts: 4
Joined: 14 Jun 2010, 08:01

Re: Pseudo 2-lead component that has a trace between pads

#7 Post by pin » 05 Aug 2010, 07:12

tinker1 wrote:.....A related question would be how to design a 2-lead component, such as an inductor, antenna, fusible link, etc, ......
Probably it is hard to implement this feature into present design, in which any track is considered as zero impedance. A special class of components having attached PCB sub-layout (spiral, meander, ...) instead of a pattern could solve this problem in rather clean way. There has been a discussion on possibility to store small layouts as submodules for repeated applications. If this were solved, the only remaining feature would be allowing to assign a component symbol to such "layout component". Easy, isn't it? ;)

Alex
Technical Support
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Joined: 14 Jun 2010, 06:43

Re: Pseudo 2-lead component that has a trace between pads

#8 Post by Alex » 06 Aug 2010, 08:11

We understand that it is sometimes necessary to save patterns with tracks. This is in our feature list, but I don't know when it will be done because it requeres significant changes in library structure.

rick.curl
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Joined: 14 Jun 2010, 16:46

Re: Pseudo 2-lead component that has a trace between pads

#9 Post by rick.curl » 30 Dec 2010, 10:09

I just tried creating a pattern consisting of two through-hole pads with a long skinny surface mount pad connecting them. This seems to do what you want. The two pads will be electrically connected together on the pattern, but Diptrace does not realize that they are connected.
When you run a DRC you will get errors because of the touching pads.

-Rick

Alex
Technical Support
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Re: Pseudo 2-lead component that has a trace between pads

#10 Post by Alex » 05 Jan 2011, 07:34

DRC finds short circuits between pads, but it doesn't know it's correct or not. If you are sure that it's correct, just don't pay attention to these DRC errors.

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