Ryan Malloy
bc0f3db97c
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Add intelligent analysis and recommendation tools for KiCad designs: ## New AI Tools (kicad_mcp/tools/ai_tools.py) - suggest_components_for_circuit: Smart component suggestions based on circuit analysis - recommend_design_rules: Automated design rule recommendations for different technologies - optimize_pcb_layout: PCB layout optimization for signal integrity, thermal, and cost - analyze_design_completeness: Comprehensive design completeness analysis ## Enhanced Utilities - component_utils.py: Add ComponentType enum and component classification functions - pattern_recognition.py: Enhanced circuit pattern analysis and recommendations - netlist_parser.py: Implement missing parse_netlist_file function for AI tools ## Key Features - Circuit pattern recognition for power supplies, amplifiers, microcontrollers - Technology-specific design rules (standard, HDI, RF, automotive) - Layout optimization suggestions with implementation steps - Component suggestion system with standard values and examples - Design completeness scoring with actionable recommendations ## Server Integration - Register AI tools in FastMCP server - Integrate with existing KiCad utilities and file parsers - Error handling and graceful fallbacks for missing data Fixes ImportError that prevented server startup and enables advanced AI-powered design assistance for KiCad projects. 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>
559 lines
23 KiB
Python
559 lines
23 KiB
Python
"""
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PCB Layer Stack-up Analysis utilities for KiCad.
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Provides functionality to analyze PCB layer configurations, impedance calculations,
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manufacturing constraints, and design rule validation for multi-layer boards.
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"""
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from dataclasses import dataclass
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import logging
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import math
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import re
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from typing import Any
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logger = logging.getLogger(__name__)
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@dataclass
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class LayerDefinition:
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"""Represents a single layer in the PCB stack-up."""
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name: str
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layer_type: str # "signal", "power", "ground", "dielectric", "soldermask", "silkscreen"
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thickness: float # in mm
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material: str
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dielectric_constant: float | None = None
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loss_tangent: float | None = None
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copper_weight: float | None = None # in oz (for copper layers)
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layer_number: int | None = None
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kicad_layer_id: str | None = None
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@dataclass
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class ImpedanceCalculation:
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"""Impedance calculation results for a trace configuration."""
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trace_width: float
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trace_spacing: float | None # For differential pairs
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impedance_single: float | None
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impedance_differential: float | None
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layer_name: str
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reference_layers: list[str]
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calculation_method: str
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@dataclass
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class StackupConstraints:
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"""Manufacturing and design constraints for the stack-up."""
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min_trace_width: float
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min_via_drill: float
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min_annular_ring: float
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aspect_ratio_limit: float
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dielectric_thickness_limits: tuple[float, float]
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copper_weight_options: list[float]
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layer_count_limit: int
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@dataclass
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class LayerStackup:
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"""Complete PCB layer stack-up definition."""
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name: str
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layers: list[LayerDefinition]
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total_thickness: float
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layer_count: int
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impedance_calculations: list[ImpedanceCalculation]
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constraints: StackupConstraints
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manufacturing_notes: list[str]
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class LayerStackupAnalyzer:
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"""Analyzer for PCB layer stack-up configurations."""
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def __init__(self):
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"""Initialize the layer stack-up analyzer."""
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self.standard_materials = self._load_standard_materials()
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self.impedance_calculator = ImpedanceCalculator()
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def _load_standard_materials(self) -> dict[str, dict[str, Any]]:
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"""Load standard PCB materials database."""
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return {
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"FR4_Standard": {
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"dielectric_constant": 4.35,
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"loss_tangent": 0.02,
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"description": "Standard FR4 epoxy fiberglass"
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},
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"FR4_High_Tg": {
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"dielectric_constant": 4.2,
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"loss_tangent": 0.015,
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"description": "High Tg FR4 for lead-free soldering"
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},
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"Rogers_4003C": {
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"dielectric_constant": 3.38,
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"loss_tangent": 0.0027,
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"description": "Rogers low-loss hydrocarbon ceramic"
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},
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"Rogers_4350B": {
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"dielectric_constant": 3.48,
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"loss_tangent": 0.0037,
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"description": "Rogers woven glass reinforced hydrocarbon"
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},
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"Polyimide": {
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"dielectric_constant": 3.5,
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"loss_tangent": 0.002,
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"description": "Flexible polyimide substrate"
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},
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"Prepreg_106": {
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"dielectric_constant": 4.2,
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"loss_tangent": 0.02,
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"description": "Standard prepreg 106 glass style"
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},
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"Prepreg_1080": {
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"dielectric_constant": 4.4,
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"loss_tangent": 0.02,
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"description": "Thick prepreg 1080 glass style"
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}
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}
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def analyze_pcb_stackup(self, pcb_file_path: str) -> LayerStackup:
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"""Analyze PCB file and extract layer stack-up information."""
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try:
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with open(pcb_file_path, encoding='utf-8') as f:
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content = f.read()
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# Extract layer definitions
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layers = self._parse_layers(content)
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# Calculate total thickness
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total_thickness = sum(layer.thickness for layer in layers if layer.thickness)
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# Extract manufacturing constraints
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constraints = self._extract_constraints(content)
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# Perform impedance calculations
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impedance_calcs = self._calculate_impedances(layers, content)
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# Generate manufacturing notes
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notes = self._generate_manufacturing_notes(layers, total_thickness)
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stackup = LayerStackup(
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name=f"PCB_Stackup_{len(layers)}_layers",
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layers=layers,
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total_thickness=total_thickness,
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layer_count=len([l for l in layers if l.layer_type in ["signal", "power", "ground"]]),
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impedance_calculations=impedance_calcs,
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constraints=constraints,
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manufacturing_notes=notes
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)
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logger.info(f"Analyzed {len(layers)}-layer stack-up with {total_thickness:.3f}mm total thickness")
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return stackup
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except Exception as e:
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logger.error(f"Failed to analyze PCB stack-up from {pcb_file_path}: {e}")
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raise
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def _parse_layers(self, content: str) -> list[LayerDefinition]:
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"""Parse layer definitions from PCB content."""
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layers = []
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# Extract layer setup section
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setup_match = re.search(r'\(setup[^)]*\(stackup[^)]*\)', content, re.DOTALL)
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if not setup_match:
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# Fallback to basic layer extraction
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return self._parse_basic_layers(content)
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stackup_content = setup_match.group(0)
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# Parse individual layers
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layer_pattern = r'\(layer\s+"([^"]+)"\s+\(type\s+(\w+)\)\s*(?:\(thickness\s+([\d.]+)\))?\s*(?:\(material\s+"([^"]+)"\))?'
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for match in re.finditer(layer_pattern, stackup_content):
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layer_name = match.group(1)
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layer_type = match.group(2)
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thickness = float(match.group(3)) if match.group(3) else None
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material = match.group(4) or "Unknown"
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# Get material properties
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material_props = self.standard_materials.get(material, {})
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layer = LayerDefinition(
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name=layer_name,
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layer_type=layer_type,
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thickness=thickness or 0.0,
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material=material,
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dielectric_constant=material_props.get("dielectric_constant"),
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loss_tangent=material_props.get("loss_tangent"),
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copper_weight=1.0 if layer_type in ["signal", "power", "ground"] else None
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)
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layers.append(layer)
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# If no stack-up found, create standard layers
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if not layers:
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layers = self._create_standard_stackup(content)
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return layers
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def _parse_basic_layers(self, content: str) -> list[LayerDefinition]:
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"""Parse basic layer information when detailed stack-up is not available."""
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layers = []
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# Find layer definitions in PCB
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layer_pattern = r'\((\d+)\s+"([^"]+)"\s+(signal|power|user)\)'
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found_layers = []
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for match in re.finditer(layer_pattern, content):
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layer_num = int(match.group(1))
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layer_name = match.group(2)
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layer_type = match.group(3)
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found_layers.append((layer_num, layer_name, layer_type))
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found_layers.sort(key=lambda x: x[0]) # Sort by layer number
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# Create layer definitions with estimated properties
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for i, (layer_num, layer_name, layer_type) in enumerate(found_layers):
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# Estimate thickness based on layer type and position
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if i == 0 or i == len(found_layers) - 1: # Top/bottom layers
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thickness = 0.035 # 35μm copper
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else:
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thickness = 0.017 # 17μm inner layers
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layer = LayerDefinition(
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name=layer_name,
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layer_type="signal" if layer_type == "signal" else layer_type,
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thickness=thickness,
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material="Copper",
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copper_weight=1.0,
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layer_number=layer_num,
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kicad_layer_id=str(layer_num)
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)
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layers.append(layer)
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# Add dielectric layer between copper layers (except after last layer)
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if i < len(found_layers) - 1:
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dielectric_thickness = 0.2 if len(found_layers) <= 4 else 0.1
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dielectric = LayerDefinition(
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name=f"Dielectric_{i+1}",
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layer_type="dielectric",
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thickness=dielectric_thickness,
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material="FR4_Standard",
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dielectric_constant=4.35,
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loss_tangent=0.02
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)
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layers.append(dielectric)
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return layers
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def _create_standard_stackup(self, content: str) -> list[LayerDefinition]:
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"""Create a standard 4-layer stack-up when no stack-up is defined."""
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return [
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LayerDefinition("Top", "signal", 0.035, "Copper", copper_weight=1.0),
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LayerDefinition("Prepreg_1", "dielectric", 0.2, "Prepreg_106",
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dielectric_constant=4.2, loss_tangent=0.02),
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LayerDefinition("Inner1", "power", 0.017, "Copper", copper_weight=0.5),
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LayerDefinition("Core", "dielectric", 1.2, "FR4_Standard",
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dielectric_constant=4.35, loss_tangent=0.02),
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LayerDefinition("Inner2", "ground", 0.017, "Copper", copper_weight=0.5),
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LayerDefinition("Prepreg_2", "dielectric", 0.2, "Prepreg_106",
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dielectric_constant=4.2, loss_tangent=0.02),
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LayerDefinition("Bottom", "signal", 0.035, "Copper", copper_weight=1.0)
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]
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def _extract_constraints(self, content: str) -> StackupConstraints:
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"""Extract manufacturing constraints from PCB."""
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# Default constraints - could be extracted from design rules
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return StackupConstraints(
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min_trace_width=0.1, # 100μm
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min_via_drill=0.2, # 200μm
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min_annular_ring=0.05, # 50μm
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aspect_ratio_limit=8.0, # 8:1 drill depth to diameter
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dielectric_thickness_limits=(0.05, 3.0), # 50μm to 3mm
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copper_weight_options=[0.5, 1.0, 2.0], # oz
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layer_count_limit=16
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)
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def _calculate_impedances(self, layers: list[LayerDefinition],
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content: str) -> list[ImpedanceCalculation]:
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"""Calculate characteristic impedances for signal layers."""
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impedance_calcs = []
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signal_layers = [l for l in layers if l.layer_type == "signal"]
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for signal_layer in signal_layers:
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# Find reference layers (adjacent power/ground planes)
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ref_layers = self._find_reference_layers(signal_layer, layers)
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# Calculate for standard trace widths
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for trace_width in [0.1, 0.15, 0.2, 0.25]: # mm
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single_ended = self.impedance_calculator.calculate_microstrip_impedance(
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trace_width, signal_layer, layers
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)
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differential = self.impedance_calculator.calculate_differential_impedance(
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trace_width, 0.15, signal_layer, layers # 0.15mm spacing
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)
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impedance_calcs.append(ImpedanceCalculation(
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trace_width=trace_width,
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trace_spacing=0.15,
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impedance_single=single_ended,
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impedance_differential=differential,
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layer_name=signal_layer.name,
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reference_layers=ref_layers,
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calculation_method="microstrip"
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))
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return impedance_calcs
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def _find_reference_layers(self, signal_layer: LayerDefinition,
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layers: list[LayerDefinition]) -> list[str]:
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"""Find reference planes for a signal layer."""
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ref_layers = []
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signal_idx = layers.index(signal_layer)
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# Look for adjacent power/ground layers
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for i in range(max(0, signal_idx - 2), min(len(layers), signal_idx + 3)):
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if i != signal_idx and layers[i].layer_type in ["power", "ground"]:
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ref_layers.append(layers[i].name)
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return ref_layers
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def _generate_manufacturing_notes(self, layers: list[LayerDefinition],
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total_thickness: float) -> list[str]:
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"""Generate manufacturing and assembly notes."""
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notes = []
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copper_layers = len([l for l in layers if l.layer_type in ["signal", "power", "ground"]])
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if copper_layers > 8:
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notes.append("High layer count may require specialized manufacturing")
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if total_thickness > 3.0:
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notes.append("Thick board may require extended drill programs")
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elif total_thickness < 0.8:
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notes.append("Thin board requires careful handling during assembly")
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# Check for impedance control requirements
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signal_layers = len([l for l in layers if l.layer_type == "signal"])
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if signal_layers > 2:
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notes.append("Multi-layer design - impedance control recommended")
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# Material considerations
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materials = set(l.material for l in layers if l.layer_type == "dielectric")
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if len(materials) > 1:
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notes.append("Mixed dielectric materials - verify thermal expansion compatibility")
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return notes
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def validate_stackup(self, stackup: LayerStackup) -> list[str]:
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"""Validate stack-up for manufacturability and design rules."""
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issues = []
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# Check layer count
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if stackup.layer_count > stackup.constraints.layer_count_limit:
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issues.append(f"Layer count {stackup.layer_count} exceeds limit of {stackup.constraints.layer_count_limit}")
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# Check total thickness
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if stackup.total_thickness > 6.0:
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issues.append(f"Total thickness {stackup.total_thickness:.2f}mm may be difficult to manufacture")
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# Check for proper reference planes
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signal_layers = [l for l in stackup.layers if l.layer_type == "signal"]
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power_ground_layers = [l for l in stackup.layers if l.layer_type in ["power", "ground"]]
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if len(signal_layers) > 2 and len(power_ground_layers) < 2:
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issues.append("Multi-layer design should have dedicated power and ground planes")
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# Check dielectric thickness
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for layer in stackup.layers:
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if layer.layer_type == "dielectric":
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if layer.thickness < stackup.constraints.dielectric_thickness_limits[0]:
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issues.append(f"Dielectric layer '{layer.name}' thickness {layer.thickness:.3f}mm is too thin")
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elif layer.thickness > stackup.constraints.dielectric_thickness_limits[1]:
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issues.append(f"Dielectric layer '{layer.name}' thickness {layer.thickness:.3f}mm is too thick")
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# Check copper balance
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top_copper = sum(l.thickness for l in stackup.layers[:len(stackup.layers)//2] if l.copper_weight)
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bottom_copper = sum(l.thickness for l in stackup.layers[len(stackup.layers)//2:] if l.copper_weight)
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if abs(top_copper - bottom_copper) / max(top_copper, bottom_copper) > 0.3:
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issues.append("Copper distribution is unbalanced - may cause warpage")
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return issues
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def generate_stackup_report(self, stackup: LayerStackup) -> dict[str, Any]:
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"""Generate comprehensive stack-up analysis report."""
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validation_issues = self.validate_stackup(stackup)
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# Calculate electrical properties
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electrical_props = self._calculate_electrical_properties(stackup)
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# Generate recommendations
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recommendations = self._generate_stackup_recommendations(stackup, validation_issues)
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return {
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"stackup_info": {
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"name": stackup.name,
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"layer_count": stackup.layer_count,
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"total_thickness_mm": stackup.total_thickness,
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"copper_layers": len([l for l in stackup.layers if l.copper_weight]),
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"dielectric_layers": len([l for l in stackup.layers if l.layer_type == "dielectric"])
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},
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"layer_details": [
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{
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"name": layer.name,
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"type": layer.layer_type,
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"thickness_mm": layer.thickness,
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"material": layer.material,
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"dielectric_constant": layer.dielectric_constant,
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"loss_tangent": layer.loss_tangent,
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"copper_weight_oz": layer.copper_weight
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}
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for layer in stackup.layers
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],
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"impedance_analysis": [
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{
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"layer": imp.layer_name,
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"trace_width_mm": imp.trace_width,
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"single_ended_ohm": imp.impedance_single,
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"differential_ohm": imp.impedance_differential,
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"reference_layers": imp.reference_layers
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}
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for imp in stackup.impedance_calculations
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],
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"electrical_properties": electrical_props,
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"manufacturing": {
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"constraints": {
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"min_trace_width_mm": stackup.constraints.min_trace_width,
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"min_via_drill_mm": stackup.constraints.min_via_drill,
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"aspect_ratio_limit": stackup.constraints.aspect_ratio_limit
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},
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"notes": stackup.manufacturing_notes
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},
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"validation": {
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"issues": validation_issues,
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"passed": len(validation_issues) == 0
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},
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"recommendations": recommendations
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}
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def _calculate_electrical_properties(self, stackup: LayerStackup) -> dict[str, Any]:
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"""Calculate overall electrical properties of the stack-up."""
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# Calculate effective dielectric constant
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dielectric_layers = [l for l in stackup.layers if l.layer_type == "dielectric" and l.dielectric_constant]
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if dielectric_layers:
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weighted_dk = sum(l.dielectric_constant * l.thickness for l in dielectric_layers) / sum(l.thickness for l in dielectric_layers)
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avg_loss_tangent = sum(l.loss_tangent or 0 for l in dielectric_layers) / len(dielectric_layers)
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else:
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weighted_dk = 4.35 # Default FR4
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avg_loss_tangent = 0.02
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return {
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"effective_dielectric_constant": weighted_dk,
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"average_loss_tangent": avg_loss_tangent,
|
|
"total_copper_thickness_mm": sum(l.thickness for l in stackup.layers if l.copper_weight),
|
|
"total_dielectric_thickness_mm": sum(l.thickness for l in stackup.layers if l.layer_type == "dielectric")
|
|
}
|
|
|
|
def _generate_stackup_recommendations(self, stackup: LayerStackup,
|
|
issues: list[str]) -> list[str]:
|
|
"""Generate recommendations for stack-up optimization."""
|
|
recommendations = []
|
|
|
|
if issues:
|
|
recommendations.append("Address validation issues before manufacturing")
|
|
|
|
# Impedance recommendations
|
|
impedance_50ohm = [imp for imp in stackup.impedance_calculations if imp.impedance_single and abs(imp.impedance_single - 50) < 5]
|
|
if not impedance_50ohm and stackup.impedance_calculations:
|
|
recommendations.append("Consider adjusting trace widths to achieve 50Ω characteristic impedance")
|
|
|
|
# Layer count recommendations
|
|
if stackup.layer_count == 2:
|
|
recommendations.append("Consider 4-layer stack-up for better signal integrity and power distribution")
|
|
elif stackup.layer_count > 8:
|
|
recommendations.append("High layer count - ensure proper via management and signal routing")
|
|
|
|
# Material recommendations
|
|
materials = set(l.material for l in stackup.layers if l.layer_type == "dielectric")
|
|
if "Rogers" in str(materials) and "FR4" in str(materials):
|
|
recommendations.append("Mixed materials detected - verify thermal expansion compatibility")
|
|
|
|
return recommendations
|
|
|
|
|
|
class ImpedanceCalculator:
|
|
"""Calculator for transmission line impedance."""
|
|
|
|
def calculate_microstrip_impedance(self, trace_width: float, signal_layer: LayerDefinition,
|
|
layers: list[LayerDefinition]) -> float | None:
|
|
"""Calculate microstrip impedance for a trace."""
|
|
try:
|
|
# Find the dielectric layer below the signal layer
|
|
signal_idx = layers.index(signal_layer)
|
|
dielectric = None
|
|
|
|
for i in range(signal_idx + 1, len(layers)):
|
|
if layers[i].layer_type == "dielectric":
|
|
dielectric = layers[i]
|
|
break
|
|
|
|
if not dielectric or not dielectric.dielectric_constant:
|
|
return None
|
|
|
|
# Microstrip impedance calculation (simplified)
|
|
h = dielectric.thickness # dielectric height
|
|
w = trace_width # trace width
|
|
er = dielectric.dielectric_constant
|
|
|
|
# Wheeler's formula for microstrip impedance
|
|
if w/h > 1:
|
|
z0 = (120 * math.pi) / (math.sqrt(er) * (w/h + 1.393 + 0.667 * math.log(w/h + 1.444)))
|
|
else:
|
|
z0 = (60 * math.log(8*h/w + w/(4*h))) / math.sqrt(er)
|
|
|
|
return round(z0, 1)
|
|
|
|
except (ValueError, ZeroDivisionError, IndexError):
|
|
return None
|
|
|
|
def calculate_differential_impedance(self, trace_width: float, trace_spacing: float,
|
|
signal_layer: LayerDefinition,
|
|
layers: list[LayerDefinition]) -> float | None:
|
|
"""Calculate differential impedance for a trace pair."""
|
|
try:
|
|
single_ended = self.calculate_microstrip_impedance(trace_width, signal_layer, layers)
|
|
if not single_ended:
|
|
return None
|
|
|
|
# Find the dielectric layer below the signal layer
|
|
signal_idx = layers.index(signal_layer)
|
|
dielectric = None
|
|
|
|
for i in range(signal_idx + 1, len(layers)):
|
|
if layers[i].layer_type == "dielectric":
|
|
dielectric = layers[i]
|
|
break
|
|
|
|
if not dielectric:
|
|
return None
|
|
|
|
# Approximate differential impedance calculation
|
|
h = dielectric.thickness
|
|
w = trace_width
|
|
s = trace_spacing
|
|
|
|
# Coupling factor (simplified)
|
|
k = s / (s + 2*w)
|
|
|
|
# Differential impedance approximation
|
|
z_diff = 2 * single_ended * (1 - k)
|
|
|
|
return round(z_diff, 1)
|
|
|
|
except (ValueError, ZeroDivisionError):
|
|
return None
|
|
|
|
|
|
def create_stackup_analyzer() -> LayerStackupAnalyzer:
|
|
"""Create and initialize a layer stack-up analyzer."""
|
|
return LayerStackupAnalyzer()
|