5 Basic Steps to a Successful PCB Layout - Part 3
Be careful with layer count: Additional layers can speed routing, but if your end product will need fewer layers use caution. A working 6 layer prototype may not easily translate into a 4 layer design.
- Look carefully at connector and HDI escape routes to see if you have leveraged layers that will not be there in the reduced layer count design. If you have is there space on a different layer? Will you have to modify planes to accommodate these traces?
- On high speed designs the layer reductions can have dramatic effects on return paths. Added length, added ground or power splits, …
Here at Screaming Circuits, we see everything from single layer and up. I think the highest layer count has to have been 24 or something. In addition to the notes from the Stilwell Baker folks above, lots of layers make the fab more expensive and the assembly more of a challenge. The board will be more sensitive to the thermal reflow profile and will have a lower tolerance for rework.
Next week: Know your PCb fabricator