FR-4 (Glass Epoxy Laminate) vs PBT (unfilled): 0% composition overlap. Significantly different materials serving different application areas.
FR-4 (Glass Epoxy Laminate) vs PBT (unfilled)
Side-by-side chemical composition and mechanical property comparison.
Overview
FR-4 (Glass Epoxy Laminate)
Flame retardant woven fiberglass cloth with epoxy resin binder — the worldwide standard substrate material for printed circuit boards (PCBs). Designated NEMA grade FR-4 and IPC-4101. Good mechanical strength, dimensional stability and electrical insulation up to 130°C (Tg). Dielectric constant 4.2–4.7 at 1 MHz. Self-extinguishing (UL94 V-0). Used for single/multilayer PCBs, electrical insulation boards, structural composites in electronics, test fixtures and jigs. Available in thicknesses 0.1–50 mm.
PBT (unfilled)
Polybutylene Terephthalate — semi-crystalline polyester with fast crystallization (short cycle times), very low moisture absorption (0.15%), excellent dimensional stability, and good electrical properties. Key advantage over PA: properties nearly independent of humidity. Trade names include Ultradur (BASF), Celanex/Crastin (Celanese/DuPont), Valox (SABIC), Arnite T (DSM). Used for electrical connectors, relay housings, automotive sensors, and any precision part in humid environments.
| FR-4 (Glass Epoxy Laminate) | PBT (unfilled) | |
|---|---|---|
| Material Number | — | — |
| Category | Polymers | Polymers |
| Standard | IPC-4101 | ISO 10350 |
Chemical composition (wt%) — Pro
| Element | FR-4 (Glass Epoxy Laminate) | PBT (unfilled) | Overlap |
|---|---|---|---|
| Epoxy Resin Matrix | 35–45% | — | — |
| Glass Fiber (E-Glass) Cloth | 55–65% | — | — |
| Base Polymer (Polybutylene Terephthalate) | — | 99–99.9% | — |
Mechanical properties — Pro
| Property | FR-4 (Glass Epoxy Laminate) | PBT (unfilled) | Unit |
|---|---|---|---|
| Flexural Strength | 380–480 | — | MPa |
| Tensile Strength | 280–340 | 55–60 | MPa |
| Compressive Strength | 350–420 | — | MPa |
| Density | |||
| Glass Transition Temp (Tg) | |||
| Dielectric Constant (1MHz) | |||
| Dielectric Strength | |||
| UL94 Flammability | |||
| Water Absorption (24h) | |||
| Tensile Strength | |||
| Yield Strength | |||
| Elongation | |||
| Elastic Modulus | |||
| Density | |||
| Melting Point | |||
| Glass Transition Temp (Tg) | |||
| Water Absorption (24h) | |||
| Tensile Modulus | |||
| Elongation at Break | |||
| Charpy Impact (notched) | |||
| Melting Point | |||
| HDT/A (1.8 MPa) |
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FR-4 (Glass Epoxy Laminate) and PBT (unfilled) have significantly different compositions (0% overlap). These materials are not interchangeable and serve different application areas.
Automated assessment based on composition analysis
Frequently Asked Questions
Is FR-4 (Glass Epoxy Laminate) the same as PBT (unfilled)?
FR-4 (Glass Epoxy Laminate) and PBT (unfilled) have a 0% composition overlap. They are generally not directly interchangeable.
Can I replace FR-4 (Glass Epoxy Laminate) with PBT (unfilled)?
Generally not recommended. The compositions differ significantly (0% overlap). These materials have different alloying concepts and are intended for different applications.
What is the difference between FR-4 (Glass Epoxy Laminate) and PBT (unfilled)?
The main differences are in the following elements: overall alloying content. FR-4 (Glass Epoxy Laminate) is a Polymers grade, while PBT (unfilled) is a Polymers grade.
Related Comparisons
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