4 ms·

The most basic design rules will be provided by your PCB fab so they can vary quite a bit depending on the quality of the manufacturer and the cost you're targe

The most basic design rules will be provided by your PCB fab so they can vary quite a bit depending on the quality of the manufacturer and the cost you're targeting. Some other design rules (i.e. differential pairs) need to be computed using an engineering calculator using some data from the fab and some choices you have to make. Unless you're pushing the analog-high speed digital boundary you don't need to worry much about them, just choose arbitrary values that result in values within your fab's specs. However, most other design rules are experimentally derived by the manufacturer of each part. Look for documents called routing or layout guidelines which should be on the same page you find a part's datasheet. The manufacturer of your CPU, RAM, sensors, connectors, PMICs, and so on will usually make them and they'll often include really basic info like how many caps and how far they should be away from some pins, how to route signals to minimize reflections, and so on. But focus on the two most important words in EE: REFERENCE DESIGNS. Until you're doing mixed signal stuff, you can usually just copy reference designs wholesale and strip out the stuff you don't need. The only hard part is making sure the layers and copper weights compatible. Even professional engineers base their work on manufacturer reference designs when they can.

willis936 3y ago
I don't know the full depth of the trade space of stackup parameters. I go with what the fabs provide. While trying to do some 200 V routing recently I found out something interesting. Higher weight copper layers have thicker prepreg. This is interesting to me because the rule of thumb for 200 V clearance is "0.4 mm in outer layers and 0.2 mm in inner layers". Most prepreg is 0.1 mm, but going to 2 oz copper means 0.22 mm prepreg. This lets me route 200 V without having to worry about arcing through prepreg, specifying a more expensive board material, or going to more layers.
MrBuddyCasino 3y ago
> But focus on the two most important words in EE: REFERENCE DESIGNS. „I avoid application notes as if they were the plague, because frankly, more than 95% of them are incorrect.“ https://youtu.be/QG0Apol-oj0?si=KTdYlKAlRhGVEDfB https://youtu.be/QG0Apol-oj0?si=KTdYlKAlRhGVEDfB
- throwup238 3y ago
  Those are not the same things.

willis936 3y ago

I don't know the full depth of the trade space of stackup parameters. I go with what the fabs provide. While trying to do some 200 V routing recently I found out something interesting. Higher weight copper layers have thicker prepreg. This is interesting to me because the rule of thumb for 200 V clearance is "0.4 mm in outer layers and 0.2 mm in inner layers". Most prepreg is 0.1 mm, but going to 2 oz copper means 0.22 mm prepreg. This lets me route 200 V without having to worry about arcing through prepreg, specifying a more expensive board material, or going to more layers.

MrBuddyCasino 3y ago

> But focus on the two most important words in EE: REFERENCE DESIGNS. „I avoid application notes as if they were the plague, because frankly, more than 95% of them are incorrect.“ https://youtu.be/QG0Apol-oj0?si=KTdYlKAlRhGVEDfB https://youtu.be/QG0Apol-oj0?si=KTdYlKAlRhGVEDfB

throwup238 3y ago
Those are not the same things.