thermal-vias¶

Package name: jsl/landpatterns/thermal-vias

Thermal Via Grid Generator

This package contains the interface definition for the thermal via grid generator. The idea is that this code is used to construct a via pattern inside a QFN or QFP style package with a thermal lead on the bottom that typically ties to ground. Many times the datasheet may suggest a particular grid pattern or you want need to specify your own pattern to meet your application's requirments.

Grid Example¶

  public inst netsw : ethernet_io_lib/components/KSZ9563/module

  val tv-g = GridThermalVias(
    via-def = therm-via,
    grid-def = GridPlanner(
      pitch = 1.2,
      columns = 6,
      rows = 6
    )
  )

  make-via-grid(tv-g, netsw.C.PAD, GND)

TODO -- Add image here showing the constructed planner.

The therm-via is a reference to a pcb-via definition. Typically these vias will need to have via-in-pad = true. Depending on your fabrication technology, you may need filled = true as well.

Summary¶

Data Types¶

ThermalVias ¶

Thermal Via Interface

Multis¶

Function	Description
active?	Check if this via grid location is active.
make-thermal-vias	Generator for creating the thermal vias
via-def	Via Definition for Populating the Thermal Via Grid.

Functions¶

Function	Description
create-via-grid-module	Construct a module Instantiable to encapsulate the a thermal via grid.
make-via-grid	Generate the Via Grid Instance and place it relative to the Component

GridThermalVias ¶

Manual Grid of Thermal Vias

Constructors¶

Function	Description
GridThermalVias (+ 1)	Constructor for `defstruct GridThermalVias`

Definitions¶

ThermalVias¶

Thermal Via Interface

public deftype ThermalVias

This interface outlines the functions needed to create a thermal via grid. The idea is that the make-thermal-vias function gets called as a generator inside a pcb-module definition and targets one of the pads of a component instantiated in that module.

Multis¶

active?¶

Check if this via grid location is active.

public defmulti active? (x:ThermalVias, row:Int, column:Int) -> True|False

x: ThermalVias - ThermaVias (self)
row: Int - Zero-based Index into the grid of a via positions.
column: Int - Zero-based Index into the grid of a via positions.
Returns True|False - Thermal Via location is Active.

In this context, active means that there should be a via at this location. inactive means that no via should be placed at this location.

make-thermal-vias¶

Generator for creating the thermal vias

public defmulti make-thermal-vias (tv:ThermalVias, pt:PortInfo -- via-net?:JITXObject = ?) -> False

tv: ThermalVias - The Thermal Via type
pt: PortInfo - PortInfo for a port on a pcb-component which we will inspect for net and pad features. This cannot be a pcb-module port. Note that this a distillation of the port JITXObject into features of that port because of limitations on how / where JITXObject port objects can be used. For example, you can't use the port from component A defined in module B in the creation of a new module C.
via-net?: JITXObject - Optional Net argument that we can use to manually set the net that the created vias will be part of. This is primarily to work around issues with module and component hierarchy. It is the user's responsibility to verify that this net and the net of the port will resolve to the same net when flattened.
Returns False

This function is intended to be called from a pcb-module context.

via-def¶

Via Definition for Populating the Thermal Via Grid.

public defmulti via-def (tv:ThermalVias) -> Via

Returns Via

Functions¶

create-via-grid-module¶

Construct a module Instantiable to encapsulate the a thermal via grid.

public defn create-via-grid-module (tv:ThermalVias, pt-info:PortInfo) -> Instantiable

tv: ThermalVias - Thermal Via definition
pt-info: PortInfo - PortInfo for a port of the component that contains the pad that the via grid will be applied to. Note that, we explicitly do not pass the JITXObject here to prevent a misuse of the pcb-module construction.
Returns Instantiable - pcb-module definition with a single port via-conn that must be connected to the same net as the originating port that constructed the pt PortInfo.

This is a useful tool for construct a via grid inside a module. This module can then be instantiated and placed with respect to a component. This is a convenient way to lock the via grid relative to a component position without needing to use place on the component instance.

make-via-grid¶

Generate the Via Grid Instance and place it relative to the Component

public defn make-via-grid (tv:ThermalVias, pt:JITXObject -- offset:Pose = ?)

tv: ThermalVias - Thermal Via Definition
pt: JITXObject - Port on a component whose pad the thermal via grid will live on.
offset: Pose - Optional offset to place the grid with respect to the component

GridThermalVias¶

Manual Grid of Thermal Vias

public defstruct GridThermalVias <: ThermalVias
    grid-def: GridPlanner

grid-def: GridPlanner - Grid Generator This type defines the shape and construction of the grid and provides the pose locations for each via.

This type is used to manually construct a grid of vias for a component. It does not leverage the pad shape for optimization.

Example Grid¶

pcb-module circuit:
  ...
  val tv-g = GridThermalVias(
    via-def = therm-via,
    grid-def = GridPlanner(
      pitch = 1.2,
      columns = 6,
      rows = 6
    )
  )

  make-thermal-vias(tv-g, netsw.C.PAD)

Note that these functions must be called within a pcb-module
This generates a geom statement with child via statements

for the grid.

Constructors¶

GridThermalVias¶

Constructor for defstruct GridThermalVias

public defn GridThermalVias (via-def:Via, grid-def:GridPlanner)

GridThermalVias¶

Constructor for defstruct GridThermalVias

public defn GridThermalVias ( -- via-def:Via, grid-def:GridPlanner)