Several PCB laminate material manufacturers offer halogen-free laminates and prepregs with varying performance, electrical, physical, and thermal properties.
A Printed Circuit Board material that does not contain halogen elements (Chlorine, Bromine, Fluorine) above a certain threshold is considered Halogen-free.
For many years, Brominated Flame Retardants (BFRs) have been used in electronic products to diminish the risk of fire-related injury and damage, however, a growing number of companies are selecting Halogen-free PCBs due to environmental, market and legislative factors.
Typically, the Coefficient of Thermal Expansion (CTE) of halogen-free PCB laminate materials is lower than regular PCBs. In addition, they generally have higher T-288 times and Td temperatures so they can withstand higher reflow temperatures and reflow cycles.
Find out the main differences between 5 of the most commonly used halogen-free printed circuit board laminates.
| EMC | Panasonic | Panasonic | NAN YA | NAN YA | |
| Product | EM-370(D) | R-1566W / R-1551W | Meg2 (R-1577 / R-1570) | NPG-150N | NPG-170N |
| Type | Halogen Free High Tg Epoxy | Halogen Free High Tg Epoxy | Halogen Free High Tg Epoxy | Halogen Free Mid Tg Epoxy | Halogen Free High Tg Epoxy |
| IPC-4101E | /127 /128 /130 | /127 /128 | /127 /128 /130 | /127 /128 | /127 /128 |
| Lead Free Process Compatible | Yes | Yes | Yes | Yes | Yes |
| Halogen Free | Yes | Yes | Yes | Yes | Yes |
| UL Approved | Yes | Yes | Yes | Yes | Yes |
| Flammability UL94 | V-0 | V-0 | V-0 | V-0 | V-0 |
| Tg – Glass Transition Temp ºC (DSC) |
175 | 148 | 170 | 150 | 170 |
| Td – Decomposition Temp ºC (TGA) | 385 | 350 | 380 | 350 | 360 |
| Dk 1 GHz | 4.10 | 4.60 | 4.14 | 3.8 – 4.0 | 4.1 – 4.3 |
| Dk 2-3 GHz | |||||
| Dk 10-12 GHz | 4 | ||||
| Df 1 GHz | 0.011 | 0.010 | 0.010 | 0.011-0.013 | 0.009-0.012 |
| Df 2-3 GHz | |||||
| Df 10-12 GHz | 0.015 | 0.013 | |||
| Moisture Absorption (%) | 0.10% | 0.14% | 0.14% | 0.20-0.30% | 0.20-0.30 % |
| CTE Z Axis (ppm/ºC) Pre Tg | 40 | 40 | 34 | 30 – 50 | 30-50 |
| % CTE Z Axis (50-200ºC) | 0.022 | ||||
| Highest of CTE X, Y Axis (PPM/ºC) Pre Tg | 15 | 15 | 16 | 13 | 13 |
| Number of Lamination Cycles | 7 | ||||
| Peel Strength – 1oz (35μm) | 0.788 kN/m | 1.8 kN/m | 1.3 kN/m | 1.40 kN/m | 1.23 kN/m – 1.57 kN/m |
| T288 (with copper) | 60 min. | 3 min. | 25 min. | 5 min. | 5 min. |
| Flexural modulus | 0.46 GPa – 0.50 GPa | 23 GPa | |||
| Volume Resistivity | 1×1010 MΩ – cm | 1×109 MΩ – cm | |||
| Surface Resistivity | 1×108 MΩ | ||||
| Dimensional stability X-Y axis | 0.01-0.03 % | 0.01-0.03 % |
In sum
The increasing demand for environmental-friendly PCBs is driving the need for halogen-free PCB laminate materials. With a variety of manufacturers and products to choose from, the evaluation and the selection process could be time-consuming. But in this article, you can quickly see a comparison of the key characteristics of a few of the most widely used halogen-free materials.