There are various materials used to make PCBs depending upon the application requirement. These include fiberglass with epoxy resins, FR4, polyimide, Teflon, and so on. Polyimide and FR4 are widely used; however, polyimide offers many benefits. So, what is polyimide? It is a high-performing polymer made of imide monomers. They have good heat and electrical resistance and high mechanical strength, and hence find applications in PCBs, especially flexible boards. Certain properties of polyimide PCBs enable their usage in mission critical applications such as aerospace and defense.
An Overview of Polyimide Material
As mentioned, it is a polymer of imide monomers. Polyimide occurs naturally and it can also be made synthetically. Polyimides can be classified into three types— aliphatic, semi-aromatic, and aromatic compounds. They are most commonly produced by the reaction between dianhydride and a diamine. Synthetic polyimides find a wide application in flexible PCBs. Aside from PCBs, polyimide finds application in cables, displays, fuel cells, and insulation films. Kapton® is a common element used in thermal systems, which is a polyimide made from condensing pyromellitic dianhydride and 4,4′-oxydianiline. This polyimide was developed by DuPont in the 1960s.
Beneficial Features of Polyimide PCBs
Here are some peculiar features of polyimide, which make them beneficial for certain PCB applications:
- They have a high dielectric, as well as tensile strength, and this makes them flexible as well as durable.
- They have a high heat, chemical, and electricity resistance, and hence offer stability over a wide temperature range.
- They have an arc resistance of almost 143 seconds.
- Integration and mounting of components is easier on these boards compared to FR4 ones.
- Polyimide acts as a natural adhesive, and can withstand high temperatures and mechanical stresses.
- Being a natural adhesive, it offers a good bond strength even at high temperatures.
- They offer tight tolerances and have a high-quality surface with thin walls.
- With further advancements such as using oligomeric dianiline, polyimides can be made moisture resistant.
- Polyimides are not brittle like their other counterparts such as FR4.
- Polyimides have a specific gravity of up to 1.6 g/cm cube.
- At 1GHz, they have a dielectric constant of 4.2.
So, do you think polyimide PCBs would suit your application requirements? If you have any doubts, you can always consult a reliable PCB manufacturer and assembler to seek answers. Also, ensure the PCBs are RoHS compliant and meet the OSHA standards. Players such as Rigiflex would not only help you make the right decision but also offer customized end-to-end PCB solutions. Rigiflex is a known manufacturer of custom flex and rigid-flex PCBs with a market presence of over 20 years.