PFA-Based Prepregs and Their Potential in PCB Applications
As a composite material supplier always looking for better ways to do things, being able to design and implement biobased prepreg solutions is a priority. That being the case, our team researched the possibility of producing biobased printed circuit boards (PCBs) using a poly (furfuryl alcohol) PFA resin.
If you’re interested in knowing the details of our research and its results, you can check out the white paper here. In the end, our team determined that PFA-based prepregs do have potential in PCB applications. However, there are some hurdles to overcome first.
Making PCBs More Environmentally Friendly
PCBs have historically been made exclusively with synthetic materials. Like most other tech companies, we understand that synthetic materials come with their own environmental concerns. If there are bio-based alternatives, they are worth exploring. That was exactly the point of our research into PFA-based prepregs for PCBs.
We engineered PCB prototypes using a PFA resin. We then put the prototypes through their paces. The good news is that they proved successful during electrical tests. The bad news is that they also exhibited a high void content. Until that particular issue is worked out, PFA-based prepregs aren’t quite ready to be the de facto standard for PCB applications.
More About the Test Results
Although our PFA-based prepregs did not pass every test, we still consider them a success. They point the way to creating future prepregs that could become drop-in replacements for PCBs. With that said, let us look at some of the test results in more detail:
1. Physical Properties
We tested a variety of prototypes for their physical properties. For example, one prepreg with a zero-tack level did not perform well. Poor bonding between the plies suggested a PCB that could easily peel apart. On the other hand, another prepreg with a medium-tack level showed much better adhesion. This suggests that a higher flow during the curing process creates a better end product.
2. Thermal Properties
The thermal properties of a prepreg play a role in material processing. Without getting into all the details, our team learned that curing temperature matters here. If temperature is such that it facilitates condensation generation, greater void formation becomes a problem.
3. Flammability
We tested our prototypes according to the UL-94 standard. Each specimen was oriented vertically and exposed to flame for 10 seconds. Once the flame was removed, each specimen extinguished instantly. This test proved that our material was worthy of a V-0 rating for flammability.
Challenges With PFA Resins
PFA resins have been investigated for quite some time. Our recent research allowed us to overcome many of the challenges other projects have identified. But there is still more to overcome before PFA prepregs are appropriate for large scale PCB manufacturing. The biggest among them is the condensation reaction during curing.
High condensation is the chief mechanism behind void formation and content. In turn, condensation also influences many of the material characteristics that are crucial to PCBs. If moisture content is too high, you end up with lower resistivity, higher permittivity, and higher loss tangent values.
As a composite material supplier and a company that focuses heavily on specialized composites, we are firmly committed to the future of PFA-based prepregs and their potential in PCB applications. Biobased prepregs could very well be the future of advanced composites.
In the meantime, more research is necessary. There are ways around the challenges our research project identified. And when those challenges are overcome, we will be left with a more environmentally sustainable way to produce the PCBs so critical to modern technology.