majiayu000 Capacitor Similarity Calculator Skill
Guidance for working with CapacitorSimilarityCalculator in the lib-electronic-components library.
For metadata-driven similarity architecture, see /similarity-metadata:
- SpecImportance levels (CRITICAL, HIGH, MEDIUM, LOW, OPTIONAL)
- ToleranceRule types (exactMatch, percentageTolerance, minimumRequired, etc.)
- SimilarityProfile contexts (DESIGN_PHASE, REPLACEMENT, COST_OPTIMIZATION, etc.)
- Calculator integration patterns and gotchas
Overview
The CapacitorSimilarityCalculator compares capacitors based on:
- Capacitance value - Must match for high similarity
- Package size - 0402, 0603, 0805, etc.
- Voltage rating - Should be compatible
- Dielectric type - X5R, X7R, C0G, etc.
Applicable Types
ComponentType.CAPACITOR
ComponentType.CAPACITOR_CERAMIC_MURATA
ComponentType.CAPACITOR_CERAMIC_TDK
ComponentType.CAPACITOR_CERAMIC_SAMSUNG
ComponentType.CAPACITOR_CERAMIC_YAGEO
ComponentType.CAPACITOR_ELECTROLYTIC_NICHICON
// Any type starting with "CAPACITOR_"
Returns false for null type.
Similarity Scoring
| Condition | Score |
|---|---|
| Same value, same package, same voltage | ~0.8+ |
| Same value, different package | ~0.5-0.7 |
| Same package, different value | ~0.3 |
| Different everything | ~0.0-0.3 |
Capacitance Value Extraction
| MPN Pattern | Value |
|---|---|
104 in MPN |
100nF (10×10⁴ pF) |
103 in MPN |
10nF (10×10³ pF) |
100N |
100nF |
10U |
10µF |
Common Manufacturers & Patterns
Murata GRM Series
GRM 188 R 71 H 104 K A01 D
│ │ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │ └── Packaging
│ │ │ │ │ │ │ └────── Termination
│ │ │ │ │ │ └──────── Tolerance (K=10%)
│ │ │ │ │ └──────────── Value (104=100nF)
│ │ │ │ └────────────── Voltage (H=50V)
│ │ │ └───────────────── Dielectric (71=X7R)
│ │ └──────────────────── Thickness
│ └──────────────────────── Size (188=0603)
└──────────────────────────── Series
Samsung CL Series
CL 10 B 104 K B8 NNNC
│ │ │ │ │ │ │
│ │ │ │ │ │ └── Packaging
│ │ │ │ │ └───── Voltage (B8=25V)
│ │ │ │ └─────── Tolerance (K=10%)
│ │ │ └─────────── Value (104=100nF)
│ │ └────────────── Dielectric (B=X7R)
│ └───────────────── Size (10=0603)
└──────────────────── Series
Yageo CC Series
CC 0603 KRX 7R 9 BB 104
│ │ │ │ │ │ │
│ │ │ │ │ │ └── Value (104=100nF)
│ │ │ │ │ └───── Voltage (BB=50V)
│ │ │ │ └─────── TCC code
│ │ │ └────────── Dielectric (7R=X7R)
│ │ └────────────── Tolerance (K=10%)
│ └─────────────────── Size (0603)
└────────────────────── Series
Cross-Manufacturer Matching
// Murata vs Samsung same value/size
calculator.calculateSimilarity("GRM188R71H104KA01D", "CL10B104KB8NNNC", registry);
// Returns >= 0.5 (both 100nF, 0603)
Dielectric Types
| Type | Characteristics | Temp Range |
|---|---|---|
| C0G/NP0 | Stable, low loss | -55 to +125°C |
| X5R | Higher capacity | -55 to +85°C |
| X7R | General purpose | -55 to +125°C |
| Y5V | High capacity, variable | -30 to +85°C |
Test Examples
// Same Murata capacitor
calculator.calculateSimilarity("GRM188R71H104KA01D", "GRM188R71H104KA01D", registry);
// Returns ~0.8
// Same value, different package
calculator.calculateSimilarity("GRM188R71H104KA01D", "GRM21BR71H104KA01D", registry);
// Returns ~0.5-0.7
// Different values
calculator.calculateSimilarity("GRM188R71H104KA01D", "GRM188R71H103KA01D", registry);
// Returns ~0.3 (100nF vs 10nF)
// Cross-manufacturer
calculator.calculateSimilarity("GRM188R71H104KA01D", "CL10B104KB8NNNC", registry);
// Returns >= 0.5
Learnings & Quirks
Value Notation
- E-series notation:
104= 10×10⁴ pF = 100nF - Last digit is multiplier (power of 10)
473= 47×10³ pF = 47nF
Package Size Mapping
| Imperial | Metric | Murata Code |
|---|---|---|
| 0402 | 1005 | 155 |
| 0603 | 1608 | 188 |
| 0805 | 2012 | 21 |
| 1206 | 3216 | 31 |
Voltage Code Variations
- Different manufacturers use different voltage codes
- Murata: H=50V, Samsung: B8=25V
- Always verify voltage compatibility
Dielectric Compatibility
- X7R and X5R are often interchangeable for general use
- C0G is preferred for precision applications
Unicode Gotcha: Micro Sign (Milestone 2, January 2026)
Critical Bug: The micro sign µ (U+00B5) becomes Greek capital MU Μ (U+039C) when uppercased:
"0.1µF".toUpperCase() // Returns "0.1ΜF" NOT "0.1µF"!
Impact: If parseCapacitanceValue() uses toUpperCase() before checking for "µF", the check fails silently, returning null. This causes capacitance comparison to be skipped, reducing similarity from ~1.0 to ~0.33 (package match only).
Solution: Replace µ→u and Μ→u before normalizing:
String normalized = value.replace("µ", "u").replace("Μ", "u");
normalized = normalizeValue(normalized); // Now safe to toUpperCase
if (normalized.contains("UF")) { // Matches both µF and plain UF
Lesson: Always handle Greek-origin SI prefixes (µ, Ω) carefully in string normalization logic.