Merge branch 'master' of https://github.com/lab11/socitrack

hardware/tottag/rev_n/README.md

@@ -2,3 +2,66 @@ Rev N
 =====
 
 Draft export, not yet finalized or fab'd
+
+
+Fabrication Notes
+-----------------
+
+> n.b., the .brd file is the authority, this is a convenience copy of the text
+> from the .brd file.
+
+### Stackup
+
+Designed for CircuitHub Std Fab: 4-Layer, 0.6mm
+
+    Order   Name    Matrl   Dscrpt  Dielec  Thk(mm) CuWgt(oz)
+      1:    Top     Copper  Signal          0.035   1oz
+                    2116    Prepreg 4.5     0.12
+      2:    Route2  Copper  Ground          0.035   1oz
+                    FR4     Core    4.6     0.23
+      3:    Route15 Copper  Pwr/Gnd         0.12    1oz
+                    2116    Prepreg 4.5     0.12
+      4:    Bottom  Copper  Sig/Gnd         0.035   1oz
+
+
+### Impedence Control
+
+50Ω for Ultra Wideband RF [5~8 GHz]
+ - Controlled traces run from U2-S2-{-U7-A1,-A2,-S4-A3}
+ — UWB traces are priority signals
+
+50Ω for Ultra Wideband XTal [38.4 MHz]
+ - Controlled traces run from U2-X4-{C3, C4}
+
+50Ω for Bluetooh RF [2.4 GHz]
+ - Controlled traces run from U1-L7-L8-A4
+
+All modeled as Coplanar waveguide.
+
+    SaturnPCB Calculator Configuration:
+     Conductor Width  = 0.22 mm (8.7 mil)
+     Conductor Height = 0.12 mm (4.7 mil)
+     Conductor Gap    = 0.15 mm (5.9 mil)
+     Er               = 4.5
+     [W/H=1.836 < 2, √]
+     Modeled Z        = 49.94 Ω
+
+
+### Panelization
+
+Any OK.
+OK to leave mouse bite tabs any edge.
+Designated tab areas are suggestions only, and have no parts or traces.
+
+
+### BGAs and Vias
+
+Parts U1 and U2 are BGAs with 4mm micro vias in pads.
+Okay to plug any/all vias in design.
+Okay to tent any/all vias in design [should already be tented].
+
+
+### Silkscreen
+
+Some legacy parts have silk outlines very close to copper.
+Okay to crop/cut silk aggressively as-needed.