With many types of Printed Circuit Boards (PCBs) existing, it makes a lot of sense to understand how each of these boards work. Today, it is possible for a PCB to have multiple use cases, such as circuit boards being used in the communications and the aerospace industries.
When it comes to the optimization of the boards, one key factor is to make sure that the performance is not affected by the design. Today, PCB consumers have to choose from a wide range of options, including but not limited to flexible, rigid, rigid-flexible and double-sided PCBs. One type of circuit board that is often overlooked is the stretchable PCB.
What Does a Stretchable PCB Mean?
From the “surface meaning,” you can define it to be a type of Printed Circuit Board (PCB) that can be stretched or have the length extended considerably.
However, there is more to the stretchable type of circuit boards. Here are some of the additional key points you need to know about it:
Based off Stretchable Electronics
Let us start by saying that the stretchable PCB is one of the core components of the broader stretchable electronics. According to Wikipedia, stretchable electronics (which are also called elastic circuits), are a “group of technologies for building electronic circuits by depositing or embedding electronic devices and circuits onto stretchable substrates.” Examples of the stretchable substrates are polyurethanes and silicones.
The Importance of Stretchable PCBs
Printed Circuit Boards (PCBs) with a stretchable design are made in line with the success of the conformable electronics, which have to do with the modifications of electronic products to fit into different use cases.
Thus, the birthing of stretchable PCBs helped to further that cause, especially when you consider that these circuit boards are now used in some real-world applications, such as wearable electronics, intelligent bandages and smart textiles.
Best Practices for Making Stretchable PCBs
As stretchable PCBs are not so popular as the others, it is not surprising that some PCB manufacturers don’t give it a shot. However, you can rely on professional stretchable PCB manufacturers to give you value for your money.
Now, these boards are manufactured with utmost focus on certain factors. Here are some of the best practices and design guidelines for the stretchable circuit boards:
1. Stretch-Rigid Technology
Sometimes, the stretchable PCB is mistaken for the flexible circuit board, especially because of the flexibility the two offers. However, they are not the same.
Now, when it comes to the technology used, the stretchable PCB is better off manufactured with a technological process called the stretch-rigid technology. It is a combination of stretching and rigid process technologies – a better concept when compared to the traditional rigid-flex process technology.
2. The Concept of the “Horseshoe Shape” Design
Besides the flexibility it offers, the stretchable PCB is subject to some critical design iterations that take time and can be complicated.
Ideally, it is common for the PCB to be prone to “straight marks,” but this can be avoided by the use of the horseshoe shape design. The idea behind this design is to make the copper traces into the horseshoe shape. This way, it becomes possible to prevent damage done to the copper found on the substrate flex.
Another reason for using the horseshoe shape design is to enable the accommodation of the extension and the change of the length of the circuit board, especially when it is stretched (to the limits).
Stretchable PCB Material and Properties
The base material, which serves as the primary material, is one important consideration when evaluating the potential performance or functionality of a circuit board. The idea is that if the base material is excellent, then the PCB’s performance will follow a similar approach.
Therefore, we want to talk about the base material used for the stretchable PCB and how it influences the performance.
TPU-Foil Basis
The first point to note is that the base material used for stretchable PCB is based on the Thermoplastic Polyurethane (TPU)-Foil. In addition, the material is highly-elastic and helps solidify the lamination of the copper foils.
Varied Designs
The base material is available in different forms and modifications. For example, you can find both the hard and the soft modifications.
One unique thing about stretchable PCB’s base material is the versatile usage, as it can be used with the following:
- Building materials, such as leather imitation for (home and office) furniture.
- Mattresses
- Gaskets
- Shoe soles and;
- Pipes
Base Material Properties
The base material used for the stretchable PCB typically has the following physical and electrical properties or features:
- Excellent thermoformability and weldability
- Chemical Stability: stretchable PCB’s base material can potentially fight against overt chemical exposure to the following: dilute acids, oils, solvents, ozone and tar.
- The material has a higher UV and weather resistance.
- Biocompatible
- Resistant to both hydrolysis and microbial
Stretchable PCB & Non-Flat Devices
The design of Printed Circuit Boards (PCBs) is to allow for flexibility in design. For that purpose, different circuit boards have been developed to meet the different and increasing requirements of newer devices.
Now that the likes of wearable devices (wearables) and a wide range of other devices having non-flattened surfaces is on the increase, the stretchable PCB can help fill that void.
What this circuit board’s design does is to allow for the foldability and bendability of the non-flat devices. This way, it becomes easier to “tilt” or “bend” these devices in whichever direction.
With that being said, the typical applications of the stretchable PCBs include:
- Biomedical applications
- Plastics with pressure sensors
- Smart textiles
- Consumer clothing and;
- Complex positioning devices
Benefits of the Stretchable Circuit Boards
If you finally decide to settle for the stretchable PCBs, here are some of the potential advantages that it offers:
- It offers an excellent low dielectric constant, which helps to bolster the electrical transmission of signals.
- Excellent thermal management capabilities.
- Stretchable PCBs reduce both the space and weight of the circuit board.
- The connections are uniform, especially those of the electrical properties of high-speed applications.
Final Words
Away from the rigid and the flexible Printed Circuit Boards (PCBs) – it is time to try something new. With the characteristics of this circuit board, you will, among many other things, benefit from the flexible adaptations to changing flexing requirements, as well as the reduction of the costs of assembling the board.
