Introduction
When selecting materials for printed circuit boards (PCBs), one of the most important considerations is surface energy. This refers to the degree to which the surface of the board interacts with other substances, such as adhesives and inks. A PCB with high surface energy will bond more readily with other materials than one with low surface energy.
High Surface Energy PCBs
PCBs with high surface energy are often preferred for applications that involve bonding, such as surface mount technology (SMT) assembly. These boards exhibit a greater affinity for adhesives and inks, which means they will form stronger and more reliable bonds with these materials. As a result, high surface energy PCBs are often favored in applications where high performance and durability are essential, such as in the aerospace and medical industries.
A typical example of a PCB with high surface energy is copper. Copper's high surface energy makes it an excellent choice for PCBs, as it will bond readily with other materials, such as epoxies and solder masks. The high surface energy of copper also makes it easy to print specific patterns onto the board, as the ink will adhere readily to the surface.
Low Surface Energy PCBs
In contrast, PCBs with low surface energy exhibit weaker bonds with adhesives and inks. These materials may not adhere as well to the surface of the board, which could lead to poor performance and reliability over time. In general, low surface energy PCBs are best suited for applications where bonding is not a primary concern, such as in the production of single-sided, through-hole boards.
Materials with low surface energy include polymers, such as PTFE (polytetrafluoroethylene) and polyester. These materials are often used in low surface energy PCBs, as they resist bonding with adhesives and inks. While this can be an advantage in some applications, it can also make it more difficult to print patterns onto the surface of the board.
Conclusion
In summary, the surface energy of printed circuit boards is an important consideration when selecting materials for a particular application. PCBs with high surface energy are preferred for applications that involve bonding, while low surface energy PCBs are better suited for applications where bonding is not a primary concern. Understanding the properties of different materials and their relative surface energies is key to selecting the right PCB for your needs.
References
- Horowitz, P., & Hill, W. (2015). The Art of Electronics. Cambridge: Cambridge University Press.
- Laminates Overview - Rogers Corp. (2022). Retrieved 6 May 2022, from https://rogerscorp.com/-/media/Files/PDFs/QMI/Laminates-overview.pdf.