Making a 4-layer PCB but Encounterining Routing Issues

Question

Hello,

I am trying to make a 4-layer pcb with the following layers: TOP, BOTTOM, GND, and VCC. I made GND and VCC layers, and made polygons covering the GND and VCC layers that are assigned to each respective layer and named GND and VCC respectively (See the FIG 1 & 2). However when I use autorouter, it is evident that the components on my board are not connecting to the VCC layer. The first image shows a top layer image with VCC lines routed across the surface. Shouldn't the components just connect to the VCC layer directly by passing through to that layer on the board directly?

Thank you in advance for your help!

FIGURE 1

FIGURE 2

FIGURE 3

rachaelp · Answer

autodeskguest wrote: This polygon looks awafully tiny to me.. from (0 0) to (0 1.4)? Its 0mm wide and 1.4mm tall? It needs to fill the whole pcb. I think that's just the co-ordinates of one vertex of the polygon. Also, looking at the trace width specified of 0.006 I would assume that the units are set to inches so the length of that vertex is 1.4 inches rather than 1.4mm. But you are right, he needs to ensure it covers the entire board area. Hi Nicholas, So, I think part of the issue here is expectations of what you will get from running the autorouter. Unfortunately there are very few boards where you can just press go on the autorouter and it will just work, and that's not just EAGLE, that's any tool at any price. Autorouters just aren't that good that they can replace the skills and experience of a PCB designer. You should think of the autorouter more like an assistance tool, you need to set things up and guide it to route what you want it to route. So, personally I never use is because I know I can do a far better job that it will do anyway, but I would probably just manually breakout your VCC/GND pins to vias so they connect the the power and ground planes directly and then autoroute the rest. Make sure you tell the autorouter it's not allowed to use your inner plane layers. Then route your highest priority signals first and keep telling it groups of signals in priority until all your important stuff is done, tidy up anything it's not routed to your satisfaction manually as you go and then let it route the remaining nets. You'll likely need to do a lot of tidying up afterwards still. Best Regards, Rachael