I have designed many two layer PCBs using Altium Designer. Customer has asked me to design a 4 layer board. I have searched the internet but I can't find any appropriate guide for switching from a 2 layer to a multi-layer board. Are there any recommendations, guides, or tutorials that I could use?
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1\$\begingroup\$ Most tools have a stack-up editor where you set the layer count and so forth. \$\endgroup\$– Peter SmithJun 12, 2016 at 13:28
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3 Answers
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Four-layer design with power and ground planes is refreshingly easy compared to two-layer! You'll want to familiarize yourself with the stackup editor in your tool, first off -- as to layer stackup selection, the "canonical", if nothing else because it's the simplest to lay out, stackup for a four layer board is signal - power - ground - signal, assuming your board runs at a single voltage.
When laying out, the signal traces stick to the two signal layers, and power and ground are accessed simply by dropping vias down where appropriate instead of having to run traces for them -- the lack of traces for power and ground running all over the board makes routing far easier. (Even though it's not great for signal integrity, even the most basic of four-layer stackups is still much better than a two-layer board.)
answered Jun 12, 2016 at 16:34
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Everything that @ThreePhaseEel has said is correct. In addition, I'd like to point out that Altium is a great tool to use for generating the designs.
Also, be sure to contact your PCB fab shop to determine what their preferred stack-up is for impedance calculations etc. They may have other limitations that you may not be aware of.
answered Jun 12, 2016 at 22:15
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1\$\begingroup\$ I would disagree with this. While they can calculate the impedance for you (they do for me), I do not rely on them to give me the stackup. I've done so in the past, and they balance the work so its easier for them rather than a more suitable stackup. Always design the stackup yourself - and let them tell what trace widths need to be. \$\endgroup\$– efox29Jun 13, 2016 at 15:03
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A digital design using a 4 layer PCB with two signal layers and two layers for GND and VCC is easier to do than a 2 layer board, the signal traces will not interfere with power traces anymore. You will need those thermal insulation pads for the power layers. A board with no thermal insulation pads might be unsolderable because the power plane layers sucks too much heat from the soldering iron. A SMD board requires vias for GND and VCC connection to the pads, these vias must be outside the pads with a short trace between via and pad for thermal insulation.
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\$\begingroup\$ Good tip regarding via placements. That answered one of my questions. \$\endgroup\$– hadezJun 13, 2016 at 17:57