Two-Layer PCB Design Tips: Achieving the Optimal Layout

[@fedimakni1200]

Regarding the last part when you mentioned the PCB that will be mounted on the top of another one, if we use a switching regulator on one board, can the switching affect the other PCB on the top of it while operating? Topics for next videos: - PCB certifications and when we really need them - PCB design for underwater application - PCB design for harsh environment (very cold weather and if we can tolerate temperature rise in that case) - Creation of passive components (cap - res - inductors) from PCB trace and how to measure their electrical properties

[@jozo314]

I'd love to see this too

[@venom_ftw9316]

Definitely interested in these topics

[@venom_ftw9316]

Definitely interested in these topics

[@shuashuashua1]

Great video as allways! Next topic i'd love to see is, routing for high voltage high power, eg. mains source full/half bridge converters. For those applications switches are huge, and mostly installed on heatsink at PCB edge with quite high distance between each other, inductors are often installed via screw terminals, and decopuling capacitors have pitch in range of 15-27 mm, so acceptable loops are much bigger than for fast digital signals, also due to dielectric withstand voltage ground plane cannot be placed in close proximity like 0.1mm, to signal/power (that also may limit copper planes number?). These boards are much different than 90% of board designs covered in web, its relative easy to find how to route HV mosfet/igbt drivers guides, but power elements are mostly ommitted. There is also high frequency commutation noise, that shouldbe considered as EMI issue.

[@josephbaker9932]

What would be the benefits of having a large number of stitching vias between Ground pours on Top and Bottom layers? Would it reduce return paths if current could flow from one layer to the other layer to get the shortest path back?

[@fabianmuhlberger6153]

Nice format! TY Zach, good explained as always. Would love to see some mixed signal design. Maybe a small class d amp with I2S? best

[@mixersinside]

Thanks for this great video. Everything was explained clearly, but the thing i really missed was discussing the benefits of routed ground in audio circuits. Routed ground is as you said "the only way to control the return path". Does this approach can ever potentially win with a ground pour?

[@Zachariah-Peterson]

The reason routed ground is preferrable at audio frequencies is because the return current tends to spread out in the ground pour at those frequencies. Due to this spreading, there is more inductance and susceptibility when using the ground pour compared to the case of a fast digital signal routed over ground pour. For a fast edge rate digital signal, most of the power is confined at much higher frequencies and it tends to exist in the ground pour region just below the trace. Also many audio interfaces are differential, so you can have ground pour but the return current will primarily exist in the opposite polarity trace, not in the ground pour.

[@mixersinside]

@@Zachariah-Peterson thank you very much for explanation. I'm not sure i fully get this - video with simulations or graphic explanation would be a blessing. I don't get why ground pour is bad in this case - it has lower impedance and potential return currents cause very low, unnoticable voltage drops when there is enough copper area. Cheers!

[@qdatfr]

Hello Zach, @AltiumAcademy with the Arduino board, you talk about the risk of crosstalk between tracks on different layers but you don't talk about risk of crosstalk between two adjacent tracks on same layers which seems to be closer one to the other (around 1mm ) (and with a much longer parallelism) than the the tracks on different layers (1.6mm). Why?

[@higaski]

Because it's impossible to work around that on a 2-layer board?

[@Zachariah-Peterson]

Did I really need to mention crosstalk on the same layer? It's mentioned so much that I shouldn't need to restate the same old thing, the crosstalk between layers is what all the students designing 2-layer digital boards seem to ignore.

[@petersage5157]

High power audio design plz? Especially interested in a deep dive into Class D power amplifiers. Literally tired of lugging around massive heat sinks. "...even down to audio frequency" ...and then not a single example of an audio frequency board. I get it. My primary interest in electronics is audio, and I can't see audio either. :p

[@87Spectr]

I say thank you very much in advance... you're great!

[@marcdraco2189]

I really enjoy these Zach (I missed this one which is bad of me) and I'll say it again, thank you for that Tee-shirt. I can't afford the software (retired, poor: pick any two) and I won't pirate it, but it won't prevent me from sending people who ask over to Altium (Academy) otherwise I'd look like a damn shill! I learned more from Rick Hartley and Eric Bogatin (which I only found thanks to you, Phil's Lab and Robert Fenerac) in a matter of WEEKS than I did in several years of college! As Rick puts it, "The energy is in the fields". That lit up a lightbulb like a supernova! Fields - in the board. That makes way more sense, oddly mostly for capacitors, from the way we're taught. I try to route the fields now, not the electrons and I'm doing far better with noise. Fields made more sense for reflecting electrons in aerials too, oddly. Of course, when you see one , the other becomes more obvious I guess. But thank you again, from a damp, rainy day in England.

[@gustavrsh]

Let's say I have a bunch of digital signal traces going from south to north on the top layer. I need to route a DC power trace on the bottom layer, and the shortest path would "cross" underneath these signal traces. (East to west) I learned that doing this is really bad for crosstalk and EMI since I would "block" a return path that is the ground pour on the bottom layer. I have the option of evading this completely, but it would lengthen the DC trace significantly (from 80mm to 140mm), making it more prone to noise and rf interference. What would you suggest in this case?

[@WrittenForYou.5]

How to select tracewidths and airgap for differential pairs?

[@Zachariah-Peterson]

Trace width and spacing are selected in order to hit a differential impedance target, such as 100 Ohms differential. The trace width, distance to the ground plane and/or ground pour, and spacing between the pairs determine the differential impedance. There are several ways to size the trace width and spacing. Usually you start with a stackup, so you already have the dielectric constant and distance to ground plane fixed. One option to select the spacing is to use a spacing that matches pin spacing on a component, you would then calculate the trace width required to reach the required differential impedance. To learn more, watch this video: kzbin.info/www/bejne/jqOsfWSFo6mZpqs

[@frankbauerful]

4+ layer boards are a lot more expensive. That alone is reason enough to use 2 layers whenever you can.

[@muhammadowaismalik3451]

4+ boards are but 4 layers are only slightly more costly then 2 layers boards. Well worth the hassle of routing for power especially in small qualities.

[@milindsharma8106]

Doesn't puttinh ground pour on noth layers cause ground loops?

[@milindsharma8106]

I mean if a component on top connects to the bottom layer ground pour with a via, as well as directly to the top layer ground pour? Or in this case should the via just not be there?

[@Zachariah-Peterson]

​@@milindsharma8106 A ground loop arises when two portions of the conductors on the same ground net have different potential. This can occur if the loop of conductor receives a changing magnetic field (which will induce an EMF in the conductor loop) or when a there is some natural potential variation between two points on the loop, such as in an earth connection shared between two different AC circuits. The first is really negligible in PCBs unless you are working at very low current levels. The 2nd case is less important because the inductance in those regions is so small that a strong magnetic field or high frequency magnetic field is needed to induce an EMF.

[@panduwilantara3070]

good

[@leeslevin7602]

👏👏👏👍