substrate module#

Substrate definitions and fabrication constraints#

This module provides classes for defining substrates with routing structures and fabrication constraints for manufacturing.

class Substrate[source]#

Bases: Structural

Substrate definition with routing structures and fabrication constraints.

Substrates can be equipped with routing and differential routing structures which will be introspected when an attempt to lookup a particular impedance is made.

A substrate should also contain the permissible Via types as well as the FabricationConstraints.

>>> class MySubstrate(Substrate):
...     constraints = MyFabricationConstraints()
...
...     class THVia(Via):
...         start_layer = 0
...         stop_layer = 1
...         diameter = 0.45
...         hole_diameter = 0.3
...         type = ViaType.MechanicalDrill
...
...     RS_50 = RoutingStructure(symmetric_routing_layers(
...         name="RS_50",
...         impedance=50 * ohm,
...         layers=symmetric_routing_layers({
...             0: RoutingLayer(
...                 trace_width=0.1176,
...                 clearance=0.2,
...                 velocity=191335235228,
...                 insertion_loss=0.0178,
...             )
...         })
...     )

>>> MySubstrate().routing_structure(50 * ohm)
RoutingStructure(name="RS_50", impedance=50 Ω)

stackup: Stackup#

constraints: FabricationConstraints#

routing_structure(impedance)[source]#

Look up a routing structure for a given impedance. The default implementation introspects the substrate for RoutingStructure objects. Override this method if you need to implement a custom lookup mechanism.

Return type:: RoutingStructure
Parameters:: impedance (Toleranced | PlainQuantity | float)

differential_routing_structure(impedance)[source]#

Look up a differential routing structure for a given impedance. The default implementation introspects the substrate for RoutingStructure objects. Override this method if you need to implement a custom lookup mechanism.

Return type:: DifferentialRoutingStructure
Parameters:: impedance (Toleranced | float)

class SubstrateContext(substrate)[source]#

Bases: Context

Access the substrate of the current design. Note that for normal use there’s a jitx.Current.subtrate convenience property that can be used instead.

>>> class MyDesign(Design):
...     substrate = MySubstrate()
...     circuit = MyCircuit()

>>> class MyCircuit(Circuit):
...     def __init__(self):
...         assert isinstance(SubstrateContext.require().substrate, MySubstrate)
...         # or the preferred and equivalent
...         assert isinstance(jitx.current.substrate, MySubstrate)

Parameters:: substrate (Substrate)

substrate: Substrate#: The substrate in the current design context.

class FabricationConstraints[source]#

Bases: Critical

Fabrication constraints for a substrate. These constraints are used to ensure that the design is manufacturable. Unless otherwise specified, these constraints are not enforced by the jitx engine. They are used for documentation purposes and can be queried by user code to generate appropriate design elements.

min_copper_width: float#: Minimum permissible copper width. This constraint will be enforced by the engine for generated copper shapes and will take precedence over other constraints and rules, such as trace width.

min_copper_copper_space: float#: Minimum permissible copper-to-copper spacing. This constraint will be enforced by the engine for generated copper shapes and will take precedence over other constraints and rules, such as clearance.

min_copper_hole_space: float#: Minimum permissible copper-to-hole spacing. This constraint will be enforced by the engine for generated copper shapes and will take precedence over other constraints and rules, such as clearance.

min_copper_edge_space: float#: Minimum permissible copper-to-board-edge spacing. This constraint will be enforced by the engine for generated copper shapes and will take precedence over other constraints and rules, such as clearance.

min_annular_ring: float#: Minimum annular ring around a hole or via.

min_drill_diameter: float#: Minimum diameter of a hole either in a pad or a via.

min_pitch_leaded: float#: Minimum distance between pad centers for leaded packages.

min_pitch_bga: float#: Minimum distance between pad centers for BGA packages.

max_board_width: float#: Maximum width of a board.

max_board_height: float#: Maximum height of a board.

min_silkscreen_width: float#: Minimum width of silkscreen.

min_silk_solder_mask_space: float#: Minimum distance between silkscreen and soldermask features.

min_silkscreen_text_height: float#: Minimum height of silkscreen text.

solder_mask_registration: float#: Minimum distance between soldermask and the edge of a copper pad.

min_soldermask_opening: float#: Minimum size of a soldermask opening shape.

min_soldermask_bridge: float#: Minimum distance between two soldermask features.

min_th_pad_expand_outer: float#: Minimum through-hole pad expansion on outer layers.

min_hole_to_hole: float#: Minimum distance between two holes, such as through-hole pads or vias.

min_pth_pin_solder_clearance: float#: Minimum distance from the outer edge of a through-hole pad to the soldermask.