Flexible circuit boards give you flexible solutions

We all know in business you need to be flexible – be just-in-time, use kanban etc etc, and this train of thought also needs to be applied to your PCB design process.

For the non techies reading this, The PCB (printed circuit board) you see today have really evolved over the years into very sophisticated circuit boards – they are not thick, stiff boards that you might have found after taking your old TV or computer apart! But thin printed substrates that are flexible and can bent onto themselves!

In our article “Libraries are the backbone of the PCB design – measure twice and design once” we discussed the flexibility that you will have by getting your PCB Libraries right first time, (i.e. a verified list of components you intend to use), and how it can save a lot of time if a printed circuit board design needs to be updated or, god forbid, redesigned. Flexible circuit boards also provide additional breathing space in a product’s design.

Currently, there are all kinds of PCB’s, here are just a few simple types – single layer, two layers, multiple layers (multi-layer), flexible, rigid, rigid-flex. With the advancement of technology, flexible PCBs are becoming more reliable and durable, such as PCBs that can withstand over 180,000 bending cycles without showing fatigue. Just look at the boom of foldable smartphones, which now typically incorporate flexible plastic OLED displays rather than glass. In order to meet consumer demands and product requirements, PCB design must be more innovative.

Again, review our previous article on wearable PCB technology, where we discussed an electronic glove that can translate sign language into speech, showing the need for more flexibility in technology. With the inclusion of 3D printing, in such industries as biomedical devices the PCB is not separated from the product, but printed directly onto it.

The initial “new tech” costs are now disappearing in new product designs, but when you consider the malleable nature of these circuit boards, the reduced number of boards connectors (which can be a major source of reliability issues), and their lightweight, these are all indirect advantages that reduce overall costs and add value to products.

Although we say leading edge, it’s interesting to read consumer PC magazines like PCMag discussing wearable fashion, or tattoos being future PCBs that interface with third-party digital devices, and could potentially provide benefits like expressing your inner emotions.
If you are interested in this you can read “You’re Never Fully Dressed Without a Tiny Printed Circuit Board” by S.C. Stuart Jul 27, 2021 about Cornell Professor Dr. Cindy Hsin-Liu Kao PCB design theory.

Felxible PCB, lets bring it down a notch so everyone can understand, what do we mean by this ?

Also known as flex circuits or flex prints, these printed circuit boards can be bent into the desired shape.

The flex PCB designs are composed of something like a polyimide plastic, (polyimides, PEEK) or a transparent conductive polyester film as a substrate material that is heat resistant so you can still traditionally solder components to it. The substrate comes as a flexible circuit when a conductive layer of copper is combined with a polyimide dielectric layer. To appropriately use these thin layers, a nesting technique is used to keep circuit boards close to each other without interfering with each other. The purpose of this article is not technical so we will not go into other terminology in regarding the flexible PCB such as: Looping, Etching, Routing, Ground Planes.

A skilled PCB designer can help you answer the brief using the latest technology, but you must also understand the traditional component providers and manufacturing process to manage new product setup, timelines, and costs.

Enhanced PCB durability

The adoption of flexible PCBs is also increasing due to factors like reliability and durability. Because these circuit boards have fewer connectors and are lightweight and malleable, they are able to absorb vibrations with minimal impact on any internal components. Some flexible PCBs are even durable enough to endure 200,000 bending cycles! Besides their resistance to vibration, flexible circuits can also withstand extreme temperatures, corrosion, and moisture exposure — making them ideal for use in harsh environments or challenging conditions commonly encountered in medical, automotive, industrial, and transportation industries.

Flexible printed circuit boards can also be reinforced with stiffening substrates if necessary to increase their reliability. Circuits subjected to continuous vibrations and mechanical stress, such as those in off-road vehicles and construction equipment, benefit from this process.

Reduced PCB component and assembly costs.

Although rigid printed circuit boards typically cost less to manufacture than flexible ones (which require more specialist processing equipment, such as vacuum lamination presses), flexible circuits do offer some cost savings, connectors can be a significant cost item.
Flex PCBs typically use fewer cables, connectors, wire harnesses, and overall parts, so they take less time to manufacture and install. Depending on the circumstances, this can be extremely cost-effective.
With the possibility of printing circuit boards on human skin, innovative PCB designers can really provide “flexibility” within your product design.

Wearable electronics are growing increasingly more comfortable and more powerful. A next step for such devices might include electronics printed directly onto the skin to better monitor and interface with the human body.

Photo Credit : ACS APPLIED MATERIALS & INTERFACES.
Read the full article “Print These Electronic Circuits Directly Onto Skin ” on Spectrum IEEE