PCB-Knowledge.md

@@ -9,11 +9,19 @@ Knowledge gleaned from failure.
 
 ## Vendors
 
+When ordering PCBs, review the [stack layout](https://docs.oshpark.com/services/four-layer/), tolerances, and the substrate material (FR-4 or [Rogers](https://morepcb.com/rogers-pcb-material/)) for the vendor.
+
 - [Oshpark](https://oshpark.com/)
-  - Pros: Trusted, quick, purple, USA
+  - Pros: Trusted, quick, purple, USA, [Design Resources](https://hackaday.io/project/162998-the-rise-and-fall-of-pulses/log/168604-osh-park-4-layer-coplanar-waveguide)
   - Cons: substrate spikes on the edges
-- Trusted Chinese vendors [Fast-PCB](https://www.fast-pcb.com/), [JLCPCB](https://jlcpcb.com/), [PCBWay](https://www.pcbway.com/)
-- Needs Review: [Advanced Circuits](https://www.4pcb.com/), [PCBgogo](https://www.pcbgogo.com/), [Sunstone](https://www.sunstone.com/), [Avanti Circuits](https://www.avanticircuits.com/), [PCBcart](https://www.pcbcart.com/), [ACE PCB](https://ace-pcb.com/), [Circuit Graphics](https://www.circuitboard.com/)
+- [Circuit Graphics](https://www.circuitboard.com/)
+  - Pros: Quick, USA (SLC), Cheap, Lets us use our material
+  - Cons: Difficult with *hard* substrates like Rogers
+- [PCBWay](https://www.pcbway.com/)
+  - Pros: Reasonable job with Rogers materials
+  - Cons: China
+- Other Chinese vendors [Fast-PCB](https://www.fast-pcb.com/), [JLCPCB](https://jlcpcb.com/)
+- Needs Review: [Advanced Circuits (4pcb)](https://www.4pcb.com/), [PCBgogo](https://www.pcbgogo.com/), [Sunstone](https://www.sunstone.com/), [Avanti Circuits](https://www.avanticircuits.com/), [PCBcart](https://www.pcbcart.com/), [ACE PCB](https://ace-pcb.com/)
 - DO NOT BUY: Aisler, nextPCB
 - [PCBShopper](https://pcbshopper.com/) to compare prices