Epoxy PCB

A Unified Guide to FR-1, FR-2, FR-3 & High-Tg FR-4 Laminates (Epoxy PCB)

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Epoxy PCB Family at a Glance

Laminate	IPC Slash Sheet	Core Reinforcement	Resin System	Typical Tg	Punch-ability	Pb-Free Reflow	Relative Cost (to FR-4 = 1.0)
FR-1	/21, /22	Paper	Phenolic*	125 – 135 °C	★★★	✖	0.40
FR-2	/10, /11	Paper	Phenolic*	100 – 110 °C	★★★	✖	0.35
FR-3	/12	Paper	Epoxy	120 – 135 °C	★★☆	Borderline (<245 °C)	0.55
FR-4 (High-Tg)	/126, /130	Woven Glass	Epoxy (enhanced)	170 – 200 °C	☆	✔ (260 °C)	1.00

* Although FR-1/FR-2 use phenolic resin, their production route and epoxy compatibility place them inside the “epoxy-class” supply chain.

Epoxy PCB Fabrication

HIGHPCB is one of the largest Rigid PCB manufacturing factories in China, click on the link to see more.

Why Epoxy-Class Laminates?

Cost tiers for every budget

from throw-away toys (FR-1) to automotive radar boards (FR-4 Tg 190 °C).

Scalable processing

steel-rule punch for paper cores, CNC/laser for glass-epoxy multilayers.

Better solder-mask adhesion

than pure phenolic; lower moisture uptake than CEM-1.

RoHS & REACH-ready

all grades available in halogen-free or V-0 flame-retardant versions.

highpcb is one of the largest PCB assembly factories in China, click here to see more.

Application Matrix

Market Segment	FR-1	FR-2	FR-3	High-Tg FR-4
Battery toys / promotional gadgets	● ● ●	● ● ●	● ●	–
Wall chargers ≤ 15 W	● ●	● ● ●	● ● ●	–
Appliance controllers	–	● ● ●	● ● ●	● ● ●
LED drivers (≤ 40 W)	–	●	● ● ●	● ● ●
Industrial & automotive Pb-free	–	–	–	● ● ●
High-speed (> 100 MHz)	–	–	♦ (80 MHz max)	● ● ●

= Recommended ♦ = Feasible with care – = Not recommended

Design & Fabrication Essentials

Parameter	FR-1 / FR-2	FR-3	High-Tg FR-4
Min. trace / gap	0.25 / 0.25 mm	0.20 / 0.20 mm	0.10 / 0.10 mm
Recommended copper	35 µm (50 µm ≥ 2 A)	35 – 70 µm	35 – 105 µm
Board thickness	1.2 / 1.6 mm	1.0 – 1.6 mm	1.0 – 3.2 mm, multilayer
Via plating	Not economical; use jumpers	Optional PTH	Blind / buried / filled µ-vias
Surface finish	OSP / Sn-Pb HASL	OSP / Sn / ENIG	ENIG, ENEPIG, ImAg, OSP
Max panel (punch)	350 × 450 mm	350 × 450 mm	510 × 610 mm (routed)

Grade-by-Grade Deep Dive

1. FR-1 – Ultra-Economy Paper-Phenolic

Target price: ≈ 40 % of FR-4.
Electrical: εr ≈ 5.1; suitable to ~30 MHz.
Thermal: Tg 130 °C → Sn-Pb wave only.
Ideal for: Greeting-card sound boards, LED nightlights, disposable med-strips.
Tip: Keep continuous tracks ≤ 1 A per 2 mm; add Al slug under TO-220 parts.

2. FR-2 – Low-Cost with Slightly Lower Tg

Tg 105 °C, cost ~5 % lower than FR-1.
Punchability identical to FR-1; CTI ≈ 125 V.
Great for: Budget AM/FM radios, IR remotes, 15 W chargers.
Caution: No Pb-free reflow; avoid heavy transformers.

3. FR-3 – Paper-Epoxy Bridge Grade

Epoxy resin improves bond strength & mask adhesion.
Tg 120 – 135 °C, still punch-friendly.
Selective Pb-free (≤ 245 °C) possible for light SMT.
Use-cases: 40 W LED drivers, smart plugs, appliance keypads.
Design rule: 0.20 / 0.20 mm trace/space; optional PTH if cost allows.

4. High-Tg FR-4 – Glass-Epoxy for Reflow & Multilayer

Tg 170 – 200 °C, Z-CTE 45–55 ppm /°C → robust at 260 °C reflow.
Electrical: εr 4.2@1 GHz, tan δ 0.015.
Supports: 1–16+ layers, µ-vias, controlled impedance to 28 Gb/s.
Industries: Automotive ADAS, servers, telecom, high-power lighting.
Pro-tip: Simulate thermal expansion stack-up to avoid CAF in >8-layer boards.

Quick Selection Cheat-Sheet

If you need…	Choose …	Because
Lowest possible BOM for a throw-away gadget	FR-1	Cheapest laminate; punch in one hit
Ultra-low price plus slightly more thermal margin	FR-2	Tg ≈ 105 °C; identical processing
Punchability + better solder-mask adhesion	FR-3	Epoxy resin; survives selective Pb-free
Lead-free reflow, multilayer, high-speed	High-Tg FR-4	Glass-epoxy, Tg ≥ 170 °C, µ-vias

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Everything About PCB Fabrication in HIGHPCB

Why Partner with HighPCB for Epoxy Boards?

Laminate breadth – FR-1, FR-2, FR-3, CEM-3, standard & high-Tg FR-4 in stock.
Dual tooling lines – steel-rule punch for paper cores; laser/CNC for glass-epoxy multilayers.
48-h DFM and impedance modelling for every order.
Rapid lead-times: 3-day FR-3 prototypes, 7-day FR-4 multilayers.
One-stop service: stencil, assembly, conformal coat, ICT & functional test.

Need to balance cost, thermal performance and reliability?
Request an instant epoxy PCB quote from HighPCB today—our engineers will match the perfect laminate to your design goals.