FR1 PCB

FR1 PCB Board is Ultra-Economical Paper-Phenolic Boards for High-Volume, Low-Voltage Electronics

What Exactly Is FR-1?

FR-1 is an IPC-4101 /21 & /22 laminate based on paper reinforcement (cellulose fibres) impregnated with phenol-formaldehyde resin. A thin copper foil is bonded to one side, creating a rigid yet extremely punch-friendly PCB core.

Property	Typical Value*	Design Significance
Dielectric constant ε<sub>r</sub> (1 MHz)	≈ 5.1	Acceptable to ≈ 30 MHz analog or ≤10 MHz digital
Loss tangent (1 MHz)	0.03	Low-frequency power & control circuits
Glass-transition temp T<sub>g</sub>	125 – 135 °C	Survives Sn-Pb wave; Pb-free reflow NOT permitted
Z-axis CTE (below T<sub>g</sub>)	75–90 ppm / °C	Keep aspect ratio ≤ 6 : 1 to avoid via cracks
Thermal conductivity	0.25 W / m·K	Derate high-current traces; add jumpers if >1 A
UL-94 flame class	HB (V-0 grades available on request)	Define if appliance safety is mandatory

* Confirm the exact datasheet grade for production.

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

Why Pick Single-Layer FR-1?

Lowest raw-laminate cost

~60 % of FR-4 → unbeatable BOM for toys, chargers, give-away gadgets

Light weight

Paper core ~15 % lighter than FR-4 of the same thickness

One-shot punching

Entire outline, I/O slots & keyholes die-cut in milliseconds

Sufficient insulation

CTI ≥ 150 V – suitable for 120/230 V appliances with correct creepage

Easy V-scoring & singulation

Minimal burr, no fibre pull-out

Key limitations

Cannot withstand Pb-free reflow (≥ 245 °C).
Lower mechanical strength – avoid heavy transformers or press-fit stakes.
Higher dielectric constant – not recommended above ~30 MHz.

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

Typical FR-1 Applications

Battery-powered toys, greeting-card sound modules
Wall-plug chargers and small SMPS primary boards ≤ 15 W
IR remote controls, RF key fobs (AM ≤ 27 MHz)
LED night-lights, novelty lamps
Disposable medical strips, glucose-meter test cards

FR-1 Manufacturing Flow

Step	Process Detail	Critical Parameter
CAM & tooling	Punch map, panel utilisation	Clearance ≥ 0.25 mm
Punch / drill	Steel-rule die for outline, carbide bits < 1 mm	≤ 200 hits per bit
Copper imaging & etch	Dry-film or screen resist + alkaline etch	Min trace/space 0.25 / 0.25 mm
Solder mask	Epoxy LPI (green) or blue peelable	Mask opening ≥ 0.10 mm
Surface finish	OSP (low cost) or Sn-Pb hot air; tin ≥ 8 µm	Ensure dwell < 6 s @ 245 °C
Depanelisation	Hydraulic punch	Burr ≤ 0.05 mm
Electrical test	Flying-probe + 250 V HiPot	Isolation ≥ 10 MΩ

Design Guidelines (Engineer’s Quick Sheet)

Board thickness: 1.2 mm or 1.6 mm; thinner boards may warp.
Copper weight: 35 µm standard; 50 µm for ≤ 2 A traces, add 2 mm width per amp.
Pads & annular rings: ≥ 0.30 mm; square pads resist peel-off.
No plated through-holes: Use wire jumpers, rivets or solder bridges for cross-overs.
Thermal relief: 4-spoke, spoke ≥ 0.30 mm to prevent cold solder joints.
Creepage / clearance: 2.5 mm for 250 V basic insulation (IEC 60335-1).

Power tip: add a thick-copper jumper or external Al heat-slug under TO-220 devices, as FR-1’s 0.25 W/m·K conductivity limits heat spreading.

FR-1 vs. FR-2 vs. CEM-1 vs. FR-4 (Single Layer)

Metric	FR-1	FR-2	CEM-1	FR-4
Relative cost	0.4	0.45	0.7	1.0
Punchability	Excellent	Excellent	Excellent	Moderate
Pb-free reflow	✖	✖	Borderline	✔
Wave solder (Sn-Pb)	Good	Good	Good	Excellent
Mechanical strength	Low	Low-Medium	Medium	High
Flame rating	HB (V-0 opt.)	HB	V-0	V-0

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Why Order FR-1 PCBs from HighPCB?

Dedicated steel-rule punch lines → burr-free edges, perfect datum repeatability.
Process-controlled Sn-Pb wave profiling – no blistering, no delamination.
3-day prototypes, 7–10 day mass production at Asia pricing.
Full service: stencil, SMT/through-hole assembly, in-circuit & functional test.

Slash PCB cost for your next low-voltage gadget.
Get an instant FR-1 quotation from HighPCB and launch your product faster—without breaking the budget!