FR-4


FR-4 refers to a grade of epoxy fiberglass material where the FR stands for "flame retarding". The TG130 refers to the glass transition temperature and indicates that this material will begin to deform at 130 ℃. FR-4 is the most common substrate material for rigid PCBs, particularly prototypes. In the PCB, the pre-preg and core will be made of this material.


FR-4 materials with higher glass transition temperatures are available for multi-layer boards. High TG FR-4 (TG155) boards can withstand deformation at higher temperatures of up to 155 ℃ and are suitable for extreme temperature applications.




Aluminium


Aluminum-backed PCBs can consistently increase durability and long-term reliability of a final product through temperature control and associated reductions in failure rates. Aluminum designs also deliver better mechanical stability and lower thermal expansion levels than FR-4.


Aluminum-backed PCBs have gained popularity in LED applications, including traffic lights, automotive lighting and general lighting.