Designing and manufacturing PCBs is so complex that it’s easy to forget what happens to a fully-functioning and regulated board once it leaves the shop. After a hopefully long and uneventful service life, the board will naturally reach the end of its use or become obsolete due to the presence of a revision, upgrade, or entirely new product. The business world refers to this situation as an externality: an unintended consequence of industry.
Many end-users, especially in the case of Class 1 electronic devices, would simply toss the device. Perhaps unbeknownst to them is the fact that electronics waste is quickly piling up in global landfills, with PCBs creeping up to a double-digit percentage of the total electronic waste.
While individual consumer lifestyle choices are hard to curb, a manufacturer is held responsible to a higher standard. In the event of a large amount of electronic waste, perhaps due to an error in manufacturing or recall that results in scrapped boards, the shop will need to procure a solution to printed circuit board disposal, assuming a system is not already in place.
Responsible Disposal Protects the Environment
Thus far, the rapid pace of electronics production has far outstripped efforts at reclaiming and reducing electronic waste (or e-waste) in landfills. The dangers are especially pronounced with PCBs due to heavy metals and toxic organic compounds that can leach from the waste and enter nearby water sources. While Moore’s Law has seen diminishing returns in recent years, it was not so long ago that processors and memory were routinely doubling.
Combined with the falling cost of consumer electronics in a pre-pandemic world, many electronics were disposed of far before they came close to their expected service life cessation. Although this is not a solution for all electronics, donating outdated but functional devices such as laptops and computers solves issues of waste and access to technology in a single motion. Depending on if the point(s) of failure is readily discernible and easily sourceable, a repair could be an option depending on the value of the device and its level of irreplaceability.
The Steps of Printed Circuit Board Disposal
When electronics have exhausted their usable life cycle, efforts can still be made to reduce the ecological impact at the landfill. Electronics and electronic components are removed from the substrate to reduce overall waste and provide an economic benefit to facilities. Often, PCBs have only experienced a fraction of their rated lifecycle, so recovery of the items provides value while preventing the pollutants mentioned above from reaching the environment.
Historically, recovery of these valuable materials and devices utilized manual applicator methods that are inefficient at removal and form another vector for pollutants, primarily halogenated organic compounds created from the substrate being heated above rated temperatures. More sophisticated options for retrieval use heat provided by a more inert source (IR radiation, inert gasses or liquids, etc.) or chemical processing to more safely and effectively remove solder joints. One current challenge with heat treatment arises from solders that do not contain low-temperature high-melt tin. These alloys are the only solders that sit in the sweet spot where they will melt at temperatures below what would cause damage to the components.
After returning the PCB to the bare board stage of design, the board is ready for further processing to loosen the valuable copper metal that is trapped inside the substrate:
- Crushing: Of all methods to separate, crushing performs best at dislodging the materials and recovery rate. This process is often two steps, with a sequential coarse-to-fine progression to reduce the average size of debris.
- Separation: After the bare boards have been reduced to a particulate of appropriate size, sorting methods are employed to separate the proverbial wheat from the chaff. Primarily, there are two modes to accomplishing this: gravity or magnetic. Gravity sorting can accomplish the task with an oriented gas stream that diverts lighter epoxy and glass fiber remnants from the heavier metals. At the same time, magnetic separation uses the inherent properties of the metals to its advantage to filter substrate from the aggregate. A third process, corona electrostatic separation, combines attractive electrostatic forces with a centrifuge to provide the most effective resolution of metallic and nonmetallic fractions.
Efforts to Further Reduce Landfill Waste
At this point, the vast majority of the metals have been successfully recovered, but the total substrate waste remains. While metals are highly profitable for scrap houses as they can easily be cleaned, purified, and recast, the mixture of organic and inorganic materials that constitutes the substrate materials is not so lucky. Industries are searching for solutions that can use the material as both a means of generating a greater profit and avoiding further electronic waste environmental contributions.
One difficulty is the dominance of glass fiber pieces. At a ratio of 2:1 glass fiber to epoxy resin constituents, most materials that the waste product could feasibly form would develop high-stress points during manufacturing that represent likely failure vectors. Further, the toxic organic and inorganic compounds presently restrict the processing ability of the material and field usage. Therefore, substrate waste will likely see its most effective contributions as a filler material. Composites can not only save money by incorporating recycled substrate materials into their processing but also enhance some significant mechanical and thermal properties to craft a more rugged product.
Work With A CM Who Takes Disposal as Seriously as Production
Our lifeblood at VSE is designing and producing top-notch electronics designed for customers by our team of engineers. Between our partners and us, we take exceptional care of your board as if it were our own design. Whether it’s manufacturing or printed circuit board disposal, we provide services that fully encompass all of your relevant needs.