Many companies that use printed circuit boards are fine using the standard FR4 material for their boards, and this can be a fine option. FR4 boards are affordable and effective for many applications. However, FR4 boards are not the only type of printed circuit board material out there, and some other boards may be better-suited to other applications.
One type of board material you may consider is polyimide. There may be some polyimide PCB material properties that will fit well with the board applications for your industry. If you’re just starting to use printed circuit boards, it will be useful to know which material is best before you start ordering them.
If you’re not sure whether or not polyimide/polyamide PCBs may be right for you, read on to learn about the properties of these boards and how they can affect your applications.
What Is Polyimide/Polyamide PCB Material?
A polyamide is a substance that occurs in nature, but can also be created synthetically. Examples of natural polyamides include silk and wool. Synthetic polyamides are used in a wide range of applications because of their flexibility, strength and durability. You may find polyamides in automotive applications, clothing and, of course, printed circuit boards. Polyimides, also found in flexible printed circuit boards, are imide monomer polyimides.
In addition to their flexibility, polyimide products are in high-demand due to their tremendous heat resistance, which results in their being used in everything from fuel cells to military applications, as well as printed circuit boards.
What Is FR4 PCB Material?
In fact, not all FR4 printed circuit boards are made out of the same material. The FR4 designation simply indicates the material grade and some general physical and electrical characteristics of the material.
Thus, the values for a particular FR4 circuit board may vary from manufacturer to manufacturer depending on the type of material they use. Characteristics like thermal conductivity water absorption, bond strength, Rockwell hardness, dielectric breakdown, flexural strength and other important values will not be the same for every FR4 board, but they will fall within a certain expected range so you can make your calculations accordingly.
FR4 boards generally have good durability and thermal conductivity, although if you are using your printed circuit boards for applications that generate a very high amount of heat, FR4 boards are probably not the best choice, as they can have trouble dissipating the heat away and damaging hot spots can occur. For these applications, some materials are much better at dissipating heat, including ceramic boards and other metal core printed circuit boards.
Why Choose Polyimide/Polyamide Over FR4?
The main reason you would choose polyimide/polyamide over FR4 boards is flexibility. If you are ordering flexible circuit boards, you are generally ordering circuit boards made out of polyimide/polyamide. FR4 boards are made by laminating a copper sheet to a glass epoxy panel. This creates a durable, very rigid board.
If you need to get your circuit boards into products that don’t easily admit components and will not take a rigid circuit board, your best approach will usually be to forego the FR4 PCB and go with a polyimide PCB. The disadvantage is that flexible circuit boards have less dimensional stability and different thermal properties.
Although more expensive than FR4 boards, polyimide PCB boards can potentially solve so many of your printed circuit board integration problems that many companies find it to easily be worth it. Polyimide PCB material is lightweight and flexible and great at resisting heat and chemicals. This material is widely used in a range of electronics, not just printed circuit boards, including cables and insulating film. It serves as an adhesive that resists high temperatures as well mechanical stresses.