CEM-3
CEM-3 is a composite epoxy laminate with a non-woven glass-mat core and woven-glass surface plies, giving FR-4-like appearance and drillability at lower cost.
Reference datasheet — CEM-3 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
CEM-3 grades and fills
CEM-3 is supplied in 3 conditions, soft to hard.
Compare all 3 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Halogen-free | Pick the phosphorus/ATH flame-retarded halogen-free version when EU export or customer specifications cap bromine and chlorine at 900 ppm each. | 155 | 1.4 | 106 HRM | |
High-CTI | Pick for AC mains boards and appliance control boards where CTI ≥ 600 V allows reduced creepage distance under IEC 60664 material group I; glass transition stays at 130 °C. | 155 | 1.5 | 104 HRM | |
High-Tg | Choose the Tg ≈150 °C epoxy system for lead-free reflow at 260 °C or higher operating temperature, where z-axis expansion must be kept under control. | 165 | 1.4 | 107 HRM |
Supply forms, finishes and certifications
Ways CEM-3 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
CCL | Copper-clad | Coating |
WHITE | White CEM-3 | Grade option |
STDDefault | Standard Tg (~130 °C), UL94 V-0 CEM-3 laminate/CCL | Standard supply |
What is CEM-3?
CEM-3 is a composite epoxy laminate with a non-woven glass-mat core and woven-glass surface plies, giving FR-4-like appearance and drillability at lower cost. It is used for double-sided PCBs and general insulating boards, and is available in high-Tg, halogen-free, white and CTI 600 versions as well as copper-clad stock. Maximum service temperature is 130 °C with a glass transition of 130 °C; mechanical strength and multilayer capability remain below FR-4, which is the direct alternative for demanding boards. CEM-3 has a density of 1.85 g/cm³ (0.0668 lb/in³), heavier than 67% of composite grades. Its glass-transition temperature is 130°C (266 °F). CEM-3 has a tensile strength of 160 MPa (23.2 ksi), weaker than 56% of composite grades. Elongation at break is 1.5% and the elastic modulus is 15 GPa (2.18 Msi).
What is CEM-3 used for?
- double-sided PCB substrates
- cost-sensitive electronic assemblies
- general insulating boards
Advantages
- Easy to machine — 65/100, better than 75% of composite grades
Limitations
- Hard to polish — 25/100, worse than 76% of composite grades
CEM-3 properties
Typical room-temperature values; bars are the position among composite grades.
Physical4
CEM-3 has a density of 1.85 g/cm³ (0.0668 lb/in³), heavier than 67% of composite grades. Its glass-transition temperature is 130°C (266 °F).
Mechanical11
CEM-3 has a tensile strength of 160 MPa (23.2 ksi), weaker than 56% of composite grades. Elongation at break is 1.5% and the elastic modulus is 15 GPa (2.18 Msi).
Thermal8
CEM-3 is rated for continuous service to 130°C (266 °F). It conducts heat at 0.35 W/m·K (0.202 BTU/hr·ft·°F), better than 50% of composite grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical7
CEM-3 is an electrical insulator with a dielectric strength of 32 kV/mm (812.8 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 65% of composite grades. UV resistance is fair.
Sustainability4
Producing a kilogram of CEM-3 takes about 110 MJ of energy and emits 6.5 kg of CO₂ — less than 60% of composite grades. Typical recycled content is 0%.
Manufacturability2
CEM-3's machinability is good (65/100, better than 75% of composite grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the composite family
Yield strength against density for every composite grade FabDigit runs. CEM-3 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with CEM-3
Is CEM-3 easy to machine?
Can be punched after preheating to 40–60 °C and drilled at high speed with lower drill wear than FR-4. Use carbide tooling with vacuum extraction to control glass dust and prevent delamination.
Can CEM-3 be welded?
Thermoset laminate — not weldable; join with epoxy adhesive or mechanical fasteners.
Can CEM-3 be formed, bent or molded?
Pressed from prepreg at 170–180 °C under 2–4 MPa. The cured board cannot be re-formed; only flat cutting operations apply.
CEM-3 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| epoxy resin (brominated/FR)Flame-retardant epoxy matrix with curing agent | 28 – 40 | 34 |
| non-woven E-glass mat (core)core glass mat | 30 – 45 | 38 |
| woven E-glass cloth (surface plies)top and bottom surface glass cloth | 12 – 25 | 18 |
| filler (ATH / silica / TiO2)Flame-retardant filler; white boards contain TiO2 | 2 – 15 | 8 |
| copper foil (clad grades only)18-70 um electrodeposited copper foil, clad laminates only | 0 – 12 | 0 |
What surface finishes work on CEM-3?
Standard PCB route: electroless copper and plating, screen-printed green solder mask, then HASL, OSP or ENIG. Bake boards at 105–120 °C before soldering to drive off moisture and prevent blistering.
How much does CEM-3 cost?
CEM-3 is a premium-cost composite ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
CEM-3 — frequently asked
What is CEM-3 used for?
CEM-3 is typically used for double-sided PCB substrates, cost-sensitive electronic assemblies and general insulating boards. In short: lower-cost FR-4 substitute; easier drilling than FR-4; glass-mat core composite.
What is the tensile strength of CEM-3?
CEM-3 has a typical tensile strength of 160 MPa (23.2 ksi) — weaker than 56% of composite grades. Strength varies by condition: see the 3 listed tempers.
Is CEM-3 easy to machine?
Reasonably — machinability is rated good (65/100, better than 75% of composite grades). Can be punched after preheating to 40–60 °C and drilled at high speed with lower drill wear than FR-4. Use carbide tooling with vacuum extraction to control glass dust and prevent delamination.
Can CEM-3 be welded?
Thermoset laminate — not weldable; join with epoxy adhesive or mechanical fasteners.
What surface finishes work on CEM-3?
Standard PCB route: electroless copper and plating, screen-printed green solder mask, then HASL, OSP or ENIG. Bake boards at 105–120 °C before soldering to drive off moisture and prevent blistering.
Can CEM-3 be formed, bent or molded?
Pressed from prepreg at 170–180 °C under 2–4 MPa. The cured board cannot be re-formed; only flat cutting operations apply.
What is the maximum service temperature of CEM-3?
CEM-3 is rated for continuous use to about 130°C (266 °F), and briefly to 260°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does CEM-3 cost?
CEM-3 is a premium-cost composite ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- IPC-4101 Specification for Base Materials for Rigid and Multilayer Printed Boards — IPC (2021)
- NEMA LI 1 Industrial Laminated Thermosetting Products — NEMA (1998)
- IEC 61249-2-21 (halogen-free base material requirements) — IEC (2003)
- Printed Circuits Handbook — base material properties — McGraw-Hill (2016)
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.