You have to tell DesignSpark PCB to use the newly created styles as the default ones. The next step took me awhile to figure out. I also created a via in the Pad Styles tab with a 1mm pad and a 0.4mm hole. I then went into the Spacings tab and set all the spacings I wanted: track to track, track to pad, track to via set to 0.2mm and the rest to 0.25mm. I went into Settings -> Design Technology and went to the Track Styles tab to create a style for my desired track width of 0.2mm.
The first thing I had to do before I started routing the relay board example was to configure the DesignSpark PCB file with the correct settings for my board. This works because the routing grid is applied to the center points of the trace, not the outer dimensions. That way when 2 traces touch, the track spacing is 0mm and when there’s a gap between traces the spacing is at least 0.2mm. For example, if the board design rules are 0.2mm tracks with 0.2mm spacing (10mil x 10mil) you would set the routing grid to 0.2mm. Generally you make this grid the same as the board clearance constraint. The trick to routing a board without an interactive autorouter is to route on a coarse enough grid that you can visually see then traces are the right spacing apart. I would not attempt to route complex BGA components with a package like DesignSparkPCB. It just takes longer and you have to use grids wisely, This is especially apparent with fine pitch surface mount components.
I really wish DesignSparkPCB included an interactive autorouter, but it’s still possible to do good layouts without one. I have learned the hard way that autorouters and I just don’t get along and I now route boards manually using interactive routing where possible. I have used a lot of autorouters in the past and I have never gotten satisfactory results with them. Today I will try and route the board without using the autorouter. Right now they only apply to this series, but they will be updated over time. My DesignSparkPCB libraries are now available on BitBucket. Previous installments of this series, First Day with DesignSpark PCB and Second Day with DesignSpark PCB where done with DesignSparkPCB version 1.03, I have since upgraded to version 2.00.
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