The traditional circuit board is challenging to recycle. It also takes a long time to decompose, contributing to the e-waste menace of over 60 million tons annually. Enter biodegradable PCBs, which disintegrate if you compost them, and things take a new twist. Here’s more about this PCB type, including how we expect it to transform the electronics industry.
What are Biodegradable PCBs?
Biodegradable PCBs are circuit boards that naturally break down into non-toxic elements. This property makes them safer to handle and environmentally friendly. Unlike the traditional type, it also means you can easily recycle the circuit board.
In contrast, the traditional FR4 PCB laminate is a glass fabric impregnated with a hazardous binder like epoxy resin. The resin is toxic and non-degradable in the natural environment.
Other additives that make the board toxic include flame retardants containing halogens, lead, and other elements. The newer compostable PCB takes safety a step higher by using materials that break down quickly.
Demo boards available today show water-soluble PCBs that disintegrate at higher temperatures. Let’s learn more about their production below, including the materials used to make them.
Resource: https://www.semanticscholar.org
How are Biodegradable PCBs Made?
Their fabrication partly resembles traditional glass fiber and epoxy resin or paper-based boards. To clarify the process, we divided its structure and production into the following: making the dielectric base and conductive layer, via drilling, and component assembly.
Dielectric Base
The insulating base is an organic polymer, such as polylactic acid (PLA) or sodium carboxymethyl cellulose (Na-CMC). This polymer replaces the thermosetting resin used in conventional boards.
PLA and CMC are plant-based plastics manufactured using materials extracted from agricultural waste like banana stems and wheat gluten. This source makes them harmless and biodegradable.
For mechanical strength and other characteristics, it has fiber reinforcements. The fibers can be natural cellulose or inorganic materials like glass. Modifying them alters properties like thermal performance, dielectric strength, and flammability.
Conductive Layer
The conductive layer above the dielectric layer is usually copper or polymer mixed with a conductive material, such as silver, and produced in two main ways:
One is laminating the base with copper and etching it the usual way. Another method involves printing the traces with a polymer infused with an electrically conductive material.
Via drilling and Assembly
Multilayer boards require vias. Filling the vias with a conductive paste electrically links the sheets in the stack-up. During assembly, components are attached to the board using solder or adhesive.
Resource: https://www.sciencedirect.com
Biodegradable PCB Benefits
The emergence of biodegradable PCBs brought significant changes in the electronics industry, given its many advantages. Some notable benefits are waste reduction, safety, and reduced carbon footprint. It also offers long-term cost savings.
Reduced Electronic Waste
The biodegradable PCB material quickly breaks down in controlled conditions, allowing a straightforward recycling process. The steps involved are stripping the board of its components, composting it, and removing the conductive metals for reuse.
Chemical Safety
It creates an eco-friendly PCB that uses non-toxic materials and does not form hazardous waste when disposed of. The conventional board contains toxic flame retardants and other materials that contaminate landfills and water bodies or produce toxic fumes if incarcerated.
Reduced Footprint
The materials used have a much lower carbon footprint than the traditional fiberglass and epoxy resin types. Estimates indicate a 60% reduction. In simpler terms, the reduction translates to 10.5 kg carbon savings for every square meter of the biodegradable circuit board manufactured.
Long-term Cost Savings
The biodegradation of PCB boards allows recycling to recover non-renewable materials. For instance, you can reclaim their metals for reuse. You only need to compost the board and recover the metals in the traces and vias.
Resource: https://www.sciencedirect.com
Biodegradable PCB Challenges and Limitations
Despite its various advantages, using degradable polymers to fabricate printed circuit boards has several limitations, such as low performance and durability. It’s also a growing technology that’s just gaining ground, with developers still working to better it.
Performance
Most biodegradable circuit board characteristics are comparable to that of the FR4 board, save for a few ones, like glass transition temperature (Tg) and tensile strength. Researchers are currently working to elevate them.
Durability
They are less durable in certain conditions. The reduced lifespan is mainly evident if you expose the board to harsh conditions or environments, such as temperature and humidity extremes.
Growing Technology
The technology is still in its infancy, and researchers are finding better materials to manufacture biodegradable electronic circuit boards. We expect the boards to have better characteristics in the coming days.
What are the Applications of Biodegradable PCBs?
The biodegradable circuit board has many characteristics comparable to standard PCBs like FR4. This property makes it available for prototyping and real-application needs.
For instance, it’s currently usable in both consumer and non-consumer applications. Examples include (but are not limited to) the following:
- Home appliances
- Medical gadgets
- Everyday consumer electronics
- Toys
- Agricultural devices like sensors
- Single use event technologies
- Research devices
- Educational electronics
Resource: https://www.sciencedirect.com
The Future of Biodegradable Printed Circuit Boards
With the world moving toward sustainability, recyclable circuit boards made using non-toxic, organic materials are preferable, whether wholly or partially recyclable.
Research is also building up, with more companies entering the race. We expect more to come with all these efforts, such as discovering better materials and manufacturing methods.
The efforts will also lead to cost reductions in the materials used to make them and the manufacturing process. In other words, it’s a promising future for the biodegradable, recyclable PCB and its use.
Conclusion
E-waste is becoming a significant problem in the world we live in today, making biodegradable PCBs a welcome alternative to solve the problem. These circuit boards are non-toxic and recyclable, offering benefits that range from safety to environmental conservation. With the ongoing research, we will likely see them become better than today, with better characteristics and be usable in most applications and industries.
