from collections.abc import Iterable
from typing import override
from jitx._structural import Structurable
from jitx.landpattern import Pad
from jitx.shapes import Shape
from jitx.shapes.composites import rectangle
from jitx.toleranced import Toleranced
from jitx.transform import Transform
from .. import LandpatternGenerator
from ..courtyard import ExcessCourtyard, OriginMarkerMixin
from ..grid_layout import GridLayoutInterface, GridPosition, LinearNumbering
from ..ipc import DensityLevelMixin, IPCRequirements, compute_ipc
from ..leads import LeadProfile, LeadProfileMixin, SMDLead
from ..leads.protrusions import BigRectangularLeads, SmallRectangularLeads
from ..package import PackageBodyMixin, RectanglePackage
from ..pads import GridPadShapeGeneratorMixin, SMDPadConfig
from ..silkscreen.marker import Pad1Marker
from ..silkscreen.outlines import (
InterstitialOutline,
SilkscreenLine,
SilkscreenOutline,
SoldermaskBased,
)
from .SMT_table import SMT_CHIP_DEFS, SMTChipDef
SMT_DEFAULT_HEIGHT = Toleranced(0.4, 0.1)
[docs]
def chip_lead_profile(chip: SMTChipDef) -> LeadProfile:
"""Build the IPC lead profile for a two-pin SMT chip case size.
The protrusion type selects between the two IPC-7351B fillet tables for
rectangular end components: Table 3-5 covers chips "Equal to or Larger than
1608 (0603)" and Table 3-6 those smaller. 1608 is the *metric* code -- imperial
0603 at 1.6 x 0.8 mm -- and the boundary is inclusive, so 0603 uses Table 3-5
(:data:`BigRectangularLeads`). Testing the body length as well as the width keeps
the sub-1608 reverse-geometry sizes (0204, 0306, 0505, 0508) in Table 3-6, where
their metric codes put them. Rev B gives no explicit rule for reverse geometry,
so that part is a judgement call rather than a citation.
Args:
chip: the case size definition
Returns:
the lead profile for this case size
"""
return LeadProfile(
pitch=3.14159, # not used
span=chip.length,
type=SMDLead(
length=chip.lead_length,
width=chip.lead_width,
lead_type=BigRectangularLeads
if chip.length.typ >= 1.6 and chip.width.typ >= 0.8
else SmallRectangularLeads,
),
)
[docs]
class SMTBase(
PackageBodyMixin,
LeadProfileMixin,
DensityLevelMixin,
GridPadShapeGeneratorMixin,
GridLayoutInterface,
LandpatternGenerator,
):
_num_rows: int = 2
_num_cols: int = 1
__side_fillet: float = 0
# cached value, cleared on build
__computed_ipc: IPCRequirements | None = None
def __init__(
self,
case_name: str,
*,
side_fillet: float | None = None,
height: Toleranced | None = None,
):
super().__init__()
self._case_name = case_name
chip = SMT_CHIP_DEFS[case_name]
# not used outside the constructor at the moment
# self.__chip_def = chip
self.lead_profile(chip_lead_profile(chip))
if side_fillet is not None:
self.__side_fillet = side_fillet
self.package_body(
RectanglePackage(
width=chip.width,
length=chip.length,
height=height or SMT_DEFAULT_HEIGHT,
)
)
def __base_init__(self):
super().__base_init__()
self.pad_config(SMDPadConfig())
@override
def _build(self):
self.__computed_ipc = None
super()._build()
@property
def _lead_spacing(self) -> float:
ipc = self.__compute_ipc()
return ipc.Gmin + ipc.pad_size()[0]
@override
def _pad_shape(self, pos: GridPosition) -> Shape:
pad_y, pad_x = self.__compute_ipc().pad_size()
return rectangle(pad_x, pad_y)
def _generate_layout(self) -> Iterable[GridPosition]:
half = self._lead_spacing / 2.0
return (
GridPosition(0, 0, Transform.translate(0.0, half)),
GridPosition(1, 0, Transform.translate(0.0, -half)),
)
def __compute_ipc(self):
if self.__computed_ipc is not None:
return self.__computed_ipc
density_level = self._density_level
lprofile = self._lead_profiles()[0]
lead_span = lprofile.span
lead_width = lprofile.type.width + 2.0 * self.__side_fillet
lead_protrusion = lprofile.type.lead_type
lead_fillets = lead_protrusion.fillets[density_level]
self.__computed_ipc = compute_ipc(
lead_span,
lprofile.type.length,
lead_width,
lead_fillets,
)
return self.__computed_ipc
[docs]
class SMTDecorated(SilkscreenOutline, OriginMarkerMixin, ExcessCourtyard, SMTBase):
def __base_init__(self):
super().__base_init__()
self.silkscreen_outline(
InterstitialOutline(horizontal=True).silkscreen_line(
SilkscreenLine.Vertical
),
SoldermaskBased().silkscreen_line(SilkscreenLine.XAxis),
)
[docs]
class CathodeAnodeNumbering(GridLayoutInterface):
a: Pad | None = None
c: Pad | None = None
@override
def _build(self):
for p in (self.a, self.c):
if p is not None:
Structurable._dispose(p)
self.a = None
self.c = None
super()._build()
@override
def _assign_pad(self, r: int, c: int, pad: Pad):
if r not in (0, 1) or c != 0:
raise ValueError("CathodeAnodeNumbering only supports 2 rows and 1 column")
if r == 0: # anode
self.a = pad
else: # cathode
self.c = pad
[docs]
class PolarizedSMT(CathodeAnodeNumbering, Pad1Marker, SMTDecorated):
pass
[docs]
class SMT(LinearNumbering, SMTDecorated):
pass
[docs]
class O4O2(SMT):
def __init__(self):
super().__init__(case_name="0402")
