PCB-Knowledge.md

@@ -14,12 +14,12 @@ When ordering PCBs, review the stack layout, tolerances, and substrate material
 | Vendor |  Pros  |  Cons  | Resources |
 | ------ | ------ | ------ |  -------  |
 |[Oshpark](https://oshpark.com/)|USA, Trusted, quick, purple|Substrate spikes on the edges|[4-Layer Coplanar Waveguide](https://hackaday.io/project/162998-the-rise-and-fall-of-pulses/log/168604-osh-park-4-layer-coplanar-waveguide), [Layer Stackup](https://docs.oshpark.com/services/four-layer/)|
-|[Circuit Graphics (circuitboard.com)](https://www.circuitboard.com/)|USA (SLC), Quick, Cheap, Lets us use our own material|Difficult with *hard* substrates (Rogers)||
+|[Circuit Graphics (circuitboard.com)](https://www.circuitboard.com/)|USA (SLC), Quick, Cheap, Lets us use our own material|Unreliable with *hard* substrates (Rogers)||
 |[Aisler](https://aisler.net/)|Germany||[4-Layer Stackup](uploads/8677eae4d989433f8921fc0295f53705/aisler_4layer_stackup_20200128.png), [Analysis](uploads/0aa8ac5ac462819a7724b922543cc67f/aisler_analysis.pdf)|
 |[PCBWay](https://www.pcbway.com/)|Reasonable job with Rogers|China||
 |[Fast-PCB](https://www.fast-pcb.com/)||China||
 |[JLCPCB](https://jlcpcb.com/)||China||
-|[Advanced Circuits (4pcb)](https://www.4pcb.com/)|USA|||
+|[Advanced Circuits (4pcb)](https://www.4pcb.com/)|USA|Not very responsive||
 
 - Needs Review: [Custom Circuit Boards](https://www.customcircuitboards.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/), [Precision Technologies](https://www.eprotos.com/), [JetPCB](http://us.jetpcb.com/), [EuroCircuits](https://www.eurocircuits.com/)
 - DO NOT BUY: nextPCB