RF Electronics Chapter 11: Circuit Manufacture Page 366
2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0.
2.3 but this is not controlled and the loss tangent is not specified. An advantage of FR2/3
and similar, paper based substrates are that holes and slots can be punched. This laminate
is not recommended for RF designs. FR3 has a poor heat tolerance and scorches easily.
FR3 is normally light brown with a smooth texture.
Figure 11.2 shows a typical low cost AM/FM radio manufactures using FR3 circuit board.
The advantage of being able to punch out a particular shape can be seen.
Figure 11.2. FR2/3 Printed Circuit Board for a low cost AM / FM radio. (Unknown manufacturer).
Fibreglass and Epoxy Substrates; FR4, FR408, IS400
This is a substrate consisting of a mixture of fibreglass and epoxy. It is suitable for
professional quality PCBs and has the following properties:
Table 11.1. FR4 Properties.
Dielectric Constant 4.7 at DC decreasing to 4.4 at 10 GHz.
Dissipation factor (Tan())
0.014
Q at 50 MHz 95
Max Temperature
130 C
Figure 11.3. FR4 Multilayer Printed Circuit Board. (Nokia Mobile Phone).
At James Cook University, prototype boards are milled and as a result, we have been
using FR3 for prototype PCBs since the fibreglass used in FR4 and many other PBCs is
carcinogenic. Special precautions are required to ensure that the fine fibreglass particles
produced by the PCB milling process are not inhaled. FR3 is safer in that respect, however
RF Electronics: Design and Simulation
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