Performance Comparison of PBT vs. PPS for Film Capacitor Housings

1. Key Property Differences

(1) Thermal Resistance

PBT (Polybutylene Terephthalate): Melting point ~225℃, limited long-term use below 120℃.

PPS (Polyphenylene Sulfide): Melting point 290℃, HDT 260℃, suitable for 180–220℃ continuous service.

(2) Flame Retardancy

PBT: Slow-burning (UL94 HB).

PPS: Self-extinguishing (UL94 V-0), oxygen index 44%, ideal for fire-safe applications.

(3) Molding Performance

PBT: High shrinkage (1.5–2.2%), requires post-mold sizing.

PPS: Low shrinkage (0.2–0.8%), excellent dimensional stability.

(4) Water Absorption

PBT: 0.07–0.09%, needs pre-drying.

PPS: 0.03%, minimal humidity impact.

2. PBT Characteristics

Advantages:

Balanced mechanical strength, low friction, and wear resistance.

Good electrical insulation (except high-frequency loss).

Resistant to oils, alkalis, and weak acids.

Limitations:

Notch-sensitive, poor impact strength (requires FR-PBT).

Poor hydrolysis resistance.

3. PPS Characteristics

Advantages:

Extreme Heat Resistance: Stable at 200–240℃ long-term.

Chemical Inertness: Resists most solvents (except strong oxidizers).

High Stiffness: Tensile strength up to 137MPa (GF-reinforced).

Flame Retardant: Meets aerospace/automotive standards.

Limitations:

Brittleness (modified grades like R-4/G-6 are common).

High cost (~2–3× PBT).

4. Application Scenarios

PBT:

Low-cost electronics (connectors, switches).

Automotive non-critical parts.

PPS:

High-temperature capacitors, IC trays.

Aggressive chemical environments.

Conclusion:
PPS excels in high-end applications demanding heat/flame resistance, while PBT offers cost-effective solutions for general-purpose uses. Material selection depends on temperature, budget, and precision requirements.