The physical construction of printed circuit boards has changed drastically over the years, not just because of how they look. Photolithography is a process that uses ultraviolet light to etch the pattern on the surface of silicon wafers. We can only do this by using a specific combination of chemicals, making it expensive and challenging to create large-scale PCBs at scale. Keeping their size small allows electronic components like semi rigid PCBs to move through water and air without impedance or damage easily.
Electronics are becoming increasingly small and powerful. Yes, they are even miniaturizing batteries and using less power. And technology continues to change the way we live as well as work. However, there is a concern that we can no longer trust electronics without a PCB. But what is a PCB? A PCB or Printed Circuit Board stands for the electronic circuit board. It can build circuits in gadgets such as smartphones, watches, airplanes, and cars, among other things. We can see it as the brain of a device from which we can connect all its components. The PCB is best for being rigid and gives precisely what’s needed to build gadgets in a uniform and stable manner.
The good thing about this circular layout is that we can use the internal structure of the PCB to build other components like LCDs and speakers. It makes it easier for electronic device manufacturers to create products for electronic users. So, with the development and improvement of bendable circuit boards, there’s no more room for other devices. The belief is that these devices are relatively inexpensive compared to older gadgets and much simpler to use. It’s now becoming popular among people. This is because electronics manufacturing can become more budget-friendly when making PCBs. We can also use electronics in a wider range of products. Therefore, electronics companies are now also investing in this field as well.
PCBs are boards with conductive wires in a single layer, the single most crucial component of your entire device. We will connect all other components to this PCB. This makes it easier to bring all your components together because of the PCB’s good layout and design. It is also lightweight and easy to carry. With the use of a PCB, there is also less problem setting it up.
PCBs are now being helpful as flexible as well. Electronic manufacturers can now use the same materials to build bendable circuit board. It also makes it more pliable, light, and effective for solar cells, batteries, and touch screens, used more often in newer devices. This will allow users to achieve quicker performance and make electronics slimmer. Thus, it makes it harder to build with other parts of the gadgets.
What is a semi rigid-Flex PCB?
A semi rigid-Flex PCB is a flexible PCB with the flexibility and rigidity of a rigid PCB but has an external look, feel, and function of a rigid PCB. Manufacturers make the semi-rigid layer of polyethylene terephthalate (PET). It is one of the most common materials used to build flexible PCBs. PET’s main advantages are its flexibility, transparency, and toughness. They separate the semi-rigid layer with a rigid core of either FR4 or Rogers RO4003. FR4 is a glass fiber laminated circuit board material used for the PCB core. Rogers RO4003 is the other commonly used PCB in producing semi rigid-Flex PCBs.
There are two types of semi rigid-flex: High Touch and Low Touch
High Touch Semi Rigid-Flex PCBs
They are flexible, transparent, and challenging. This semi rigid-flex PCB displays the LCDs and touch screens on most gadgets. It’s made of PET laminated to a rigid surface using either FR4 or Rogers RO4003. We commonly use it in devices that require flexibility and lightweight, such as tablets, smartphones, etc.
Low Touch Semi Rigid-Flex PCBs
They are flexible and tough but not transparent. We prepare it the same way as the High Touch Semi Rigid-Flex, but instead of being transparent, it is black. We use this type in devices that require less flexibility but durability, such as home appliances, smartphones, etc.
Both semi flex PCBs are durable and easily soldered together. This is especially with a low-temperature soldering iron. Solderability is one of the main factors that make these two durable and long-lasting electronics devices.
Most of the time, we use semi rigid-flex PCBs to build a device with the same function as a rigid PCB but with a different external look. Therefore, electronics need semi rigid-flex PCBs for their devices. The use of this kind of PCB will allow companies to create products and gadgets that we can use for almost any electronic device.
Advantages of semi rigid-Flex PCBs
It offers a plethora of advantages. First is the user-friendliness of the PCB. They are always lightweight, flexible, tough, and pliable, making them a lot easier to carry around and use. They also have an easy time setting them up on a board because of their lightweight, thinness, and flexibility. We can also use Flexible PCBs in building flexible devices such as solar cells, touch screens, and batteries. These are the main reasons electronics need semi rigid-flex PCBs for their products.
1. Reduced Packaging Size
When using semi rigid-flex PCBs, we will reduce the overall size of the finished product. Because of its greater versatility in its application. Since they’re flexible, they will allow electronics manufacturers to reduce their packaging sizes without compromising on the quality of the final product. When it comes to pricing, it’s cheaper compared with rigid PCBs while providing the same function. Semi rigid-flex PCBs are also easier to work with, making them more cost-effective for electronic manufacturers.
2. Weight Reduction
Semi rigid-flex PCB is best to be lighter compared with rigid PCBs. This is a great advantage for manufacturers because it allows them to reduce the weight and size of their products. With less weight and size, the product will also cost less. We can pass this on to their customers. Also, since it’s more lightweight and flexible, it will make using the finished products easier.
3. Improved Flexibility
Flexibility is one of the main benefits of using semi rigid-flex PCBs in products. Because it’s flexible, we can use it in many different applications. This means that manufacturers will have more jobs. They can use their products because it’s both flexible and tough, allowing them to develop devices with a lot more functionality.
4. Unique Dynamic Stability
By using semi rigid-flex PCBs, devices can have more dynamic stability. This will allow manufacturers and developers to build many more versatile products that provide high-quality performance. The PCB can also stretch, which means we can use it in many different applications.
5. Thin Profile
When it comes to performance, a thin profile is one of the essential things in devices today. We are building most of them smaller and smaller to fit inside pockets. The semi rigid-flex PCB is a lot thinner compared with rigid PCBs. This makes it easier to fit into devices, making them very light. Manufacturers need to keep their products as light and small as possible to minimize their overall weight. It will lower the cost of the finished product. We can use it in devices of extremely small size, such as smartphones, PDAs, digital cameras, etc.
For electronics manufacturers, semi rigid-flex PCBs are cheaper than the rigid type. Manufacturers can then pass on this affordable price to end-users. This will make semi rigid-flex PCBs more popular among buyers because they provide better value for their money. Semi rigid-flex PCBs will also save them from developing extra work due to their lightweight and flexibility.
7. Environmental Friendly
Semi rigid-flex PCBs are environment friendly. Because it’s so lightweight, the products containing semi rigid-flex PCBs will be a lot lighter than other electronic devices that use rigid PCBs. This means it won’t require a lot of energy to carry, install and transport them. Also, semi rigid-flex PCBs are flexible, making them easier to recycle and repair. This is a great benefit for manufacturers because they can keep their products clean and pollution-free, helping the environment.
8. Ease of Use
Semi rigid-flex PCBs are a lot easier to use than rigid PCBs. Because they are flexible, there will be fewer cases of damages. This is because they’re pliable so that they can easily bend or twist due to accidental drops or bumps. They will also be easier to install and set up in devices since they can easily fit into tight corners because of their flexibility and thinness.
9. Impact resistance
Being flexible, semi rigid-flex PCBs are immensely impacting resistant. Even if it gets stuck, dropped, or bumped, it can still keep its original shape. This is unlike rigid PCBs, which are more prone to breaking when accidentally damaged. Since we hold the microchips and components in semi rigid-flex PCBs together by flexible solder bumps, they can be bendable PCB. The PCB will remain intact even when dropped or bumped because of this stronghold.
PCB Design for Flex Electronics Manufacturing
Nowadays, flexible PCBs are being used a lot in fabricating flexible electronics. We use them so much because they can be extremely tiny and thin, making them easy to incorporate into a wide range of applications. Today there are numerous types of semi rigid-flex PCBs that you can choose from to meet the needs and requirements of your application. However, before designing these semi rigid-flex PCBs, you must consider several factors that will affect the design process, such as:
Stiffeners can provide a lot of strength and support to your semi rigid-flex PCBs. The stiffeners are usually copper or steel, which you will use to create your design. You can also use different materials like a crosshatch for the stiffener. It will help minimize the amount of deflection that occurs when there is an impact on your semi rigid-flex PCB.
2. Bending Requirements
Before designing your semi rigid-flex PCBs, it’s essential to consider the bending requirements that are helpful in the industry. The bending requirements can be a great help when designing your semi rigid-flex PCB. This will allow you to determine how the semi rigid-flex PCBs will bend. You can either use an inspection machine for this or use bend test equipment to check out how much deflection occurs in your design.
3. Mechanical Design
This can be an essential factor you must consider when designing your semi rigid-flex PCBs. It will help determine how your semi rigid-flex PCBs will bend. If you are using the conventional mechanical design procedure, you need to design the semi rigid-flex PCB to bend in a controlled manner. You must also consider the amount of deflection when bent and how much bending resistance occurs.
The soldering process is an essential factor that you must consider when designing your semi rigid-flex PCBs. You will need to make sure that the solderability of your semi rigid-flex PCBs is not affected in any way. Also, when placing the components on the board, you must solder them to not interfere with the bending and flexing of the semi rigid-flex PCB.
5. Electronic Design
This can be an essential step you must take when designing your semi rigid-flex PCBs. You must make sure that the electronic design for the semi rigid-flex PCBs is correctly designed and not misdesigned. It will enable you to achieve your desired result. It would be best to consider how much power the semi rigid-flex PCB components require and their operating temperature range.
Design Tips for Rigid-Flex PCBs
Below are a few tips that can help you in the design and creation of rigid-flex PCBs:
There are a lot of factors that will determine which semi rigid-flex PCBs you will choose. These include the level of flexibility, compatibility, material, and finish. The best way is to determine the application you will use to determine what you need.
1. Evade Pads & Vias at the Bend Zones
The semi rigid-flex PCBs will be more vulnerable to damage if they have excessively large and deep via holes. A good tip is to avoid these areas as much as possible in the design of semi rigid-flex PCBs. This will ensure that there are no excessive cuts or holes. It will also help improve the bond strength on their microchips and components. This prevents them from violation when bending the semi rigid-flex PCB and making it weak.
2. Make Use of Glass Passives
There are a lot of advantages that we can derive when using glass passives when designing semi rigid-flex PCBs. This is because it is an excellent insulator. It will also help protect the semi rigid-flex PCB from damage when accidentally dropped or bumped. There are a lot of advantages that we can gain from using glass passives in semi rigid-flex PCBs. These include:
It helps to keep the semi rigid-flex PCB cool even when used in devices with a high-power demand. This allows the microchips and components to remain stable. Also, it will enable them to be more flexible, reliable, and durable.
It prevents the semi rigid-flex PCB from bending too much when accidentally impacted or damaged.
3. Avoid Putting Too Many Connectors
It is best to leave a minimum number of connectors on semi rigid-flex boards with passive components. This will help reduce their weight and improve their flexibility and ease of installation. It would be best to place the connectors in areas where the board can easily access the flexing. This will avoid the need to solder them at a future date, allowing you to have more flexibility with the design.
Also, it would be best if you placed your connectors in a position where they will not interfere with the bending of the boards.
4. Use the Hatched Polygon when it comes to Copper Planes
If you are using copper pads for the semi rigid-flex PCB design, it is best to place them on a very large and broad EPP surface. This will help to improve their solderability when soldering. This will increase the bond strength and help ensure no cuts in the semi rigid-flex PCB during bending.
5. Ensure Empty Regions are full with Unwanted Copper Traces
If you are using semi rigid-flex PCBs in mobile and consumer electronics, the need for small passives may affect the board’s overall weight. In this case, it is best to fill up all empty spaces with additional copper traces and vias. So, there will be a minimum amount of space for the semi rigid-flex PCB, which will give it a more stable structure and make it easier to bend.
6. Use Oblique Angle for Connectors
The use of oblique angles is an excellent way to reduce the resistance by half. This is because they are not perfectly perpendicular, so they will avoid selling them later. After designing your semi rigid-flex PCB, you can now design the rigid parts using Altium Designer. When designing the rigid parts, you must make sure they fit with your semi rigid-flex PCB.
Types of Flex Electronics PCBs
Most companies manufacture all PCBs to be flexible. To state this differently, they engineer the PCBs to withstand certain levels of bending and twisting. They do not design the boards for extreme flexibility or extreme rigidity. The classification depends on the end-use of your PCB. Besides its primary use, one can engineer a flex PCB to fold or roll.
In general, flex PCBs classification includes:
1. Class 1
These are single-sided boards that are either plain or may contain special layers. They can bend just slightly, but we cannot roll them.
2. Class 2
These are double-sided boards with a rigid core surrounded by a thin layer of copper and laminate layers on both sides. Generally, we design this PCB for bending in one specific plane, like bending around the corners of a box, for example. We can roll flexible PCBs under this category but not folded because the rigid core bends when rolled.
3. class 3
We refer to multilayer flexible PCBs with special layers as “flip-chip” PCBs. These single-sided boards have one rigid layer and a flexible laminate layer on the other side. They can bend straight or roll but not fold.
4. class 4
We refer to specialized flex PCBs such as cards, backplane, and customized designs as “flexible” PCBs. They can bend in multiple directions to fit many applications like flip-chip, saddle, and half-layers
5. class 5 and 6
These are flexible laminate PCBs that are “half sheets” or “double-sided.” They contain rigid and flexible layers processed together. The degree of bending is greatly restricted and can bend in only one direction so that the maximum bending radius is about 8 mm.
6. class 7, 8, 9
These are special types of flex PCBs designed for specific applications like drones, military aircraft, and automotive electronics. Most manufacturers design them to withstand very high bending or twisting, and they do not intend to use them as flexible PCBs.
Flexible PCBs require special attention when designing rigid components. There are two reasons for this:
(1) The components like connectors can easily bend out of shape,
(2) Most connectors, pins, vias, etc., have thin walls that can easily break or bent during the design process.
Applications for need semi rigid Flex PCB
There are many applications where companies use semi rigid PCBs to fit in space constraints and be very flexible. These include automotive electronics, medical devices, wearable electronics, and cell phones. Most of these use the flip-chip method to create the individually designed semi rigid board.
To manufacture a semi rigid PCB flex, the PCB component manufacturer must follow some steps like:
1. Making a small custom board
2. Making this small custom flexible PCB component
3. Mating these two together
In this way, we can have a nonflexible (rigid) part in semi rigid (flexible) PCB.
Below is a detailed diagram of semi rigid PCB process.
We make all semi rigid PCBs of three parts: solid core, laminate, and laminate on both sides. The laminated sheet only provides the lay-flat feature. They can make these components from FR4 or FR5 material by adding several layers of copper to the board. This makes the board stiffer and more resilient to bending. We make the core of the semi rigid flex PCB using a rigid material like epoxy, glass-reinforced thermoplastics, glass-filled nylon, or metal-filled nylon.
Semi Rigid flex PCBs are so versatile that we can use them in different automotive electronics, medical devices, wearable electronics, and many others. They can also be easily processed on a standard manufacturing line or a design service provider and are significantly cost-effective when the time to market.
Flexible PCBs are essential in various applications such as automotive electronics, medical electronics, wearables, and many others.
They can also be easily processed on a standard manufacturing line or a design service provider and are significantly cost-effective when the time to market.
Though flexible PCBs are helpful in almost every electronic device, they are still not perfect. This is because semi flex PCBs will surely be better versions of both the rigid and flexible PCBs in the future and thus more widely used. Since electronics are becoming more powerful, less expensive, and futuristic, allowing them to become more common for a wider range of products, there will be no doubt that the electronics industry will use semi rigid-flex PCBs. It seems like they are here to stay. So, with the development of semi rigid-flex PCBs, there is no doubt that electronic devices will become more powerful and better.