Question: what are the different pcbs?
Answer: Single Sided PCBs. Single sided PCBs are the basic type of circuit boards, which contain only one layer of substrate or base material. ... 
Double Sided PCBs. ... 
Multi-layer PCBs. ... 
Rigid PCBs. ... 
Flexible PCBs. ... 
Rigid-Flex-PCBs. ... 
High-Frequency PCBs. ... 
Aluminum backed PCBs.