Electrical Insulation Composite · Glass Fiber Reinforced Polymer
FR-4
FR-4 is an electrical insulation composite composite — bullet-proof glass alternative. Typical values: 275 MPa yield, 1.85 g/cm³, rated to 130 °C. Available for CNC machining, Sheet metal at FabDigit.
Properties
Typical room-temperature values in the Epoxy Matrix condition. Metric first, imperial in gray. The bars show where FR-4 sits against the other 12 composite grades in the catalog.
Datasheet
| Yield strength | 275 MPa40 ksi |
|---|---|
| Tensile strength | 310 MPa45 ksi |
| Hardness | 110 HRM |
| Density | 1.85 g/cm³0.067 lb/in³ |
| Specific strength (yield ÷ density) | 149 |
| Min service temp | -40 °C-40 °F |
| Max service temp | 130 °C266 °F |
| Electrical conductivity | < 0.001 % IACSinsulator |
| Machinability | Poor20 / 100 |
| Weldability | Not recommended1 / 100 |
| Formability | Not recommended1 / 100 |
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Against other composite grades
Strength versus weight in the composite family
Yield strength against density for every composite grade FabDigit runs. FR-4 is highlighted; hover a dot for its name, or open the interactive family chart.
Manufacturability
The process limits FabDigit's quote engine applies to FR-4. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Poor20 / 100 |
|---|---|
| Cutting speed (rough / finish) | — / — |
| Minimum wall | — |
| Minimum internal radius | — |
| Drill depth limit | — |
| Best surface (machined / polished) | Ra — / — |
| Hardenable after machining | — |
Sheet metal
| Formability | Not Recommend1 / 100 |
|---|---|
| Weldability | Not Recommend1 / 100 |
Conditions and tempers
How FR-4 is supplied and what each state is for. The default is what FabDigit quotes unless your drawing says otherwise.
| Condition | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Epoxy MatrixDefault Matrix | Strongest laminate (G-10/FR-4) — structural + electrical parts | — | — | — | — |
Heat treatment and post-processing
Operations FabDigit's suppliers routinely run on FR-4, ranked by how often they make sense for this grade.
Post-processing
| Manual Deburr | Deburrstandard |
|---|---|
| Edge Break (0.5mm) | Deburr |
| CMM Inspection | Inspection |
| FAI Report | Inspection |
| Individual Bag | Packaging |
Surface finishes for FR-4
Coatings and treatments compatible with composite on the processes FR-4 runs on. Pick them in the quote configurator or call them out on the drawing.
Organic Coating
- Painting
Marking / Decoration
- Chemical Etching
- Dot Peen Marking
- Electro-chemical Etching
- Embossing / Debossing
- Ink Stamping
- Laser Marking
- Mechanical Engraving
- Vibro Engraving / Scribing
Equivalent designations
Standards and trade names that resolve to FR-4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Other
- G10 Flame RetardantGarolite FR-4
Stock forms
Raw-material forms FabDigit sources FR-4 in.
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.