Everest CORE - Product Manual |
Application Guide
INGENIA | 08/01/2019
56
Power tracks can go through
any layer from Mid 1 to Bottom is fine to exit the Everest CORE, but respecting the
intended layer stack usage is advised (see below): GND_P will be better fitted through a layer dedicated to ground
planes, as Mid 1, and POW_SUP will be better fitted in a layer dedicated to power supplies, as Mid 3 in this example.
Motor phases, however, can go through any of these, but it is of special interest to
not travel along an adjacent
path to a ground plane
, as this may cause an unwanted capacitive coupling between the motor phase and the
voltage reference of sensitive circuits. This is why the motor phases are traced along Mid 1 in the given snippet.
Proposed Layer Stack
Although many other options may be valid, here this 6-layer stack is proposed considering that is pretty standard,
and targets the lowest PCB manufacturing cost to allow routing the Everest CORE comfortably. The resulting PCB
should be around 1.6 mm thick.
Note that internal layers are defined as 70 µm copper thickness. When targeting the nominal phase current of
Everest CORE this would help minimising the number of layers required to carry the phase currents without causing
considerable losses due to self-heating. However, this might entail jumping from PCB Class 6 to Class 7 in some
cases. Consult your PCB manufacturer. Also, in very small designs where the phases copper self-heating cannot be
easily evacuated, consider selecting FR-4 dielectrics with higher glass transition temperatures: Tg = 150 ºC or even
Tg = 180 ºC.
As for the example provided, the following usage of each layer is suggested:
Layer
Purpose
Top
Components, signal tracks, GND
Mid 1
GND_D copper plane
Area in contact with the Chassis
The chassis of Everest CORE will be in direct contact with the Interface PCB surface. As the thin layer of
soldermask does not provide a sufficient isolation, it is mandatory to
keep the contact area free of
copper
. No tracks, vias, pads or (obviously) components are allowed in the contact area, which means the
signal tracks must exit the Everest Core along internal layers or Bottom layer. It is recommended to use
Mid layer 2 for the signal tracks and keep mid layer 1 as a mostly uniform ground plane connected to
GND_D.
Layer MEchanical 15 of the provided Everest CORE component indicate the minimum recommended
clearances around the contact area of the chassis.
