Fabrication of Printed Circuit Boards for Extreme Environments

circuit board

In the old days, electronics were considered to be fragile and precious. Practically everybody got scolded as a boy for putting their Coke cans on Dad’s hi-fi equipment. These days, however, new generations of consumers have grown up with much sturdier products and rapid advances in electronics are quickly changing people’s expectations about the kinds of environmental challenges that electronics should be able to stand up to. The explosive innovation in electronics has reached a kind of “tipping point” where the confluence of miniaturization, open-source software, AI and better methods of interface, and constant connection to the Internet are all contributing to a demand for a huge range of new devices that are being used in conditions unlike those that traditional electronics have typically confronted. Today’s PCB makers are being forced by market demand to produce boards that are ever tougher and can stand up to environmental challenges that would have been impossible even a few years ago.

circuit board

Conformal Coatings

One effective technique that board fabricators are using to better seal PCBs and thereby protect them from environmental stress is “conformal coating.” Conformal coating is sprayed onto the board as a liquid near the end of the fabrication process. Some types of conformal coatings cure out with solid, hard surfaces, and others cure out with a spongier surface. Conformal coating is useful as a non-electrically conductive protective layer, insulating the unit from environmental assaults. Using conformal coatings, a PCB can be protected from dust, corrosion, mold and fungus growth, moisture, salt spray, and other forms of contamination. Conformal coatings also provide a degree of thermal insulation, useful for boards that will be exposed to thermal extremes. The spongier forms of conformal coatings can also protect the board from the physical shocks arising from tough use, dropping, and mechanical vibration. Most conformal coatings include a kind of dye marker that is visible under UV light to enable inspectors to examine the uniformity of the coating during test procedures at the end of fabrication.

circuit boardLiquid Metal Capsules

One exciting new advancement in the fabrication of PCBs for extreme environments if the “self-healing” circuit board. Using liquid metal micro-capsules, engineers have successfully manufactured a PCB that can autonomously repair a rupture in its circuitry within microseconds, allowing uninterrupted operation. The microcapsules are placed all along the length of a circuit and are composed of a rigid exterior and a liquid metal interior which is made up of a gallium-iridium alloy.

circuit board

If there is a rupture anywhere along the circuit, the microcapsule is also ruptured and the liquid metal alloy flows into the gap in the circuit, restoring the connection. The engineers have so far achieve a 90% success rate. The developers of this technology have even figured out how to use it in multi-layer PCBs.

As the Internet of Things brings electronics to practically every device used by man, we can expect the demand for ever tougher circuit boards to keep increasing. Makers will be challenged like never before to keep up with the market demand for board that are as close to indestructible as possible.