Lead Free Epoxy Laminate and Prepreg

IS420 is a high performance 170°C glass transition temperature (Tg) FR-4 system for multilayer Printed Wiring Board (PWB) applications where maximum thermal performance and reliability are required.

Thermal Performance

Tg: 170°C
Td: 350°C

Electrical Performance

Dk: 4.04
Df: 0.021

Industry Approvals

IPC-4101 /98 /99 /101 /126
UL - File Number E41625

IS420 laminate and prepreg products are manufactured with a unique high performance multifunctional epoxy resin, reinforced with electrical grade (E-glass) glass fabric. This system provides improved thermal performance and low expansion rates in comparison to traditional FR-4 while retaining FR-4 processability.

In addition to this superior thermal performance, the mechanical, chemical and moisture resistance properties all equal or exceed the performance of traditional FR-4 materials. The IS420 system is also laser fluorescing and UV blocking for maximum compatibility with Automated Optical Inspection (AOI) systems, optical positioning systems and photoimagable solder mask imaging.


Product Features

  • Industry Recognition
    • UL File Number: E41625
    • Qualified to UL’s MCIL Program
    • RoHS Compliant
  • Performance Attributes
    • Lead-free assembly compatible
  • Processing Advantages
    • FR-4 process compatible
    • UV blocking and AOI fluorescence

Production & Manufacturing

Currently manufactured in Asia, Europe

Product Availability

  • Standard Material Offering: Laminate
    • 2 to 93 mil (0.05 to 2.4 mm)
    • Available in full size sheet or panel form
  • Copper Foil Type
    • HTE Grade 3
    • RTF (Reverse Treat Foil)
  • Copper Weight
    • ½ to 2 oz (18 to 70 µm) available
    • Heavier copper available
    • Thinner copper foil available
  • Standard Material Offering: Prepreg
    • Roll or panel form
    • Tooling of prepreg panels
  • Glass Fabric Availability
    • E-glass
    • Square weave glass
Property Typical Value Units Test Method
Metric (English) IPC-TM-650 (or as noted)
Glass Transition Temperature (Tg) by DSC 170 °C 2.4.25C
Decomposition Temperature (Td) by TGA @ 5% weight loss 350 °C
Time to Delaminate by TMA (Copper removed)
A. T260
B. T288
Z-Axis CTE
A. Pre-Tg
B. Post-Tg
C. 50 to 260°C, (Total Expansion)
X/Y-Axis CTE Pre-Tg 13/14 ppm/°C 2.4.24C
Thermal Conductivity 0.4 W/m·K ASTM E1952
Thermal Stress 10 sec @ 288ºC (550.4ºF)
A. Unetched
B. Etched
Pass Pass Visual
Dk, Permittivity
A. @ 100 MHz
B. @ 1 GHz
C. @ 2 GHz
D. @ 5 GHz
E. @ 10 GHz
Bereskin Stripline
Bereskin Stripline
Bereskin Stripline
Df, Loss Tangent
A. @ 100 MHz
B. @ 1 GHz
C. @ 2 GHz
D. @ 5 GHz
E. @ 10 GHz
Bereskin Stripline
Bereskin Stripline
Bereskin Stripline
Volume Resistivity
A. After moisture resistance
B. At elevated temperature
3.0 x 108
7.0 x 108
Surface Resistivity
A. C-96/35/90
B. After moisture resistance
C. At elevated temperature
3.0 x 106
2.0 x 108
Dielectric Breakdown >50 kV 2.5.6B
Arc Resistance 115 Seconds 2.5.1B
Electric Strength (Laminate & laminated prepreg) 54 (1350) kV/mm (V/mil)
Comparative Tracking Index (CTI) 3 (175-249) Class (Volts) UL 746A
ASTM D3638
Peel Strength
A. Low profile copper foil and very low profile copper foil all copper foil >17 μm [0.669 mil]
B. Standard profile copper
    1. After thermal stress
    2. At 125ºC (257ºF)
    3. After process solutions

1.14 (6.5)

1.25 (7.0)
1.25 (7.0)
1.14 (6.5)
N/mm (lb/inch)
Flexural Strength
A. Length direction
B. Cross direction
ksi 2.4.4B
Moisture Absorption 0.15 %
Flammability (Laminate & laminated prepreg) V-0 Rating UL 94
Relative Thermal Index (RTI) 130 °C UL 796
The data, while believed to be accurate and based on analytical methods considered to be reliable, is for information purposes only. Any sales of these products will be governed by the terms and conditions of the agreement under which they are sold.


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A: Initial release - 4/17
B: Corrected units for Flexural and Tensile Strength - 8/18
C: Change MOT to RTI 5/19
D: Added /126 slash sheet 02/20

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Laminate & Prepreg Manufacturing

This presentation describes the process of laminate and prepreg manufacturing.

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Laminates, Prepreg, & PCB Materials
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