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Printed Circuit Boards (PCB)

Printed Circuit BoardsEDCOR uses FR-4 PCB material for all of thier printed circuit boards.

Most printed circuit boards are manufactured using glass-reinforced epoxy laminate as the substrate. While there are a wide variety of laminates available on the market, FR-4 is both versatile and well-accepted as a standard material for PCB manufacture. FR-4 functions well as an electrical insulator, and has a good strength-to-weight ratio, and is flame resistant.

EDCOR uses single and double sided PC boards, ranging from 0.032" to 0.062" thickness. EDCOR's PC boards have a nickel solder flow. All materials are RoHS compliant.

Properties

Typical physical and electrical properties of FR-4 are as follows. LW (length wise, warp yarn direction) and CW (cross wise, fill yarn direction) refer to the fiber orientations in the plane of the board (in-plane) that are perpendicular to one another. The through-plane direction is also referred to as the z-axis.

ParameterValue
Speciļ¬c gravity/density 1.850 g/cm3 (3,118 lb/cu yd)
Water absorption −0.125 in < 0.10%
Temperature index 140 °C (284 °F)
Thermal conductivity, through-plane 0.29 W/m·K,[1] 0.343 W/m·K[2]
Thermal conductivity, in-plane 0.81 W/m·K,[1] 1.059 W/m·K[2]
Rockwell hardness 110 M scale
Bond strength > 1,000 kg (2,200 lb)
Flexural strength (A; 0.125 in) - LW > 440 MPa (64,000 psi)
Flexural strength (A; 0.125 in) - CW > 345 MPa (50,000 psi)
Tensile strength (0.125 in) LW > 310 MPa (45,000 psi)
Izod impact strength - LW > 54 J/m (10 ft·lb/in)
Izod impact strength - CW > 44 J/m (8 ft·lb/in)
Compressive strength - flatwise > 415 MPa (60,200 psi)
Dielectric breakdown (A) > 50 kV
Dielectric breakdown (D48/50) > 50 kV
Dielectric strength 20 MV/m
Relative permittivity (A) 4.8
Relative permittivity (D24/23) 4.8
Dissipation factor (A) 0.017
Dissipation factor (D24/23) 0.018
Dielectric constant permittivity 4.70 max., 4.35 @ 500 MHz, 4.34 @ 1 GHz
Glass transition temperature Can vary, but is over 120 °C
Young's modulus - LW 3.5×10^6 psi (24 GPa)
Young's modulus - CW 3.0×10^6 psi (21 GPa)
Coefficient of thermal expansion - x-axis 1.4×10−5 K−1
Coefficient of thermal expansion - y-axis 1.2×10−5 K−1
Coefficient of thermal expansion - z-axis 7.0×10−5 K−1
Poisson's ratio - LW 0.136
Poisson's ratio - CW 0.118
LW sound speed 3602 m/s
SW sound speed 3369 m/s
LW Acoustic impedance 6.64 MRayl

[1] Azar, K; Graebner J. E. (1996). "Experimental Determination of Thermal Conductivity of Printed Wiring Boards". Proceedings of the Twelfth IEEE SEMI-THERM Symposium: 169–182.
[2] Azar, K; Graebner J. E. (1996). "Experimental Determination of Thermal Conductivity of Printed Wiring Boards". Proceedings of the Twelfth IEEE SEMI-THERM Symposium: 169–182.