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- December 28, 2022
- PCB knowledge
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- 13 mins
What is FPC and how to choose a FPC manufacturer
Flexible printed circuit boards, also known as “FPC boards”, are printed circuit boards made of flexible insulating substrates. FPC can provide excellent electrical performance, meet the needs of smaller and higher-density mounting designs, and also help reduce assembly processes and enhance reliability.
FPC is the only solution to meet the miniaturization and mobility requirements of electronic products. It can be bent, wound, and folded freely, and can withstand millions of dynamic bendings without damaging the wires. It can be arranged arbitrarily according to the spatial layout requirements, and can be moved and stretched in three-dimensional space, so as to achieve the integration of component assembly and wire connection.
FPC can greatly reduce the volume and weight of electronic products, and is suitable for the development of electronic products in the direction of high density, miniaturization and high reliability.
What is the difference between FPC and rigid PCB?
Regarding the FPC, it is actually a kind of printed circuit boards, but it is quite different from the traditional printed circuit board, so it is called flexible printed circuit board. FPC generally uses PI as the base material, which is a flexible material that can be bent and flexed arbitrarily. FPC are usually used in links that require repeated flexing and some small parts, but now it is more than that. At present, smart phones are being considered bendable, which requires the use of FPC as a key technology.
PCB is the so-called printed circuit board, usually called rigid PCB, which is the support body among electronic components and is a very important electronic component. Rigid PCBs usually use FR4 as the base material, also called FR4 circuit boards, which cannot be bent or flexed. Rigid PCBs are usually used in some places that do not need to be bent and have relatively strong strength, such as computer motherboards, mobile phone motherboards, etc.
In fact, the FPC is not only a flexible circuit board, but also an important design method for connecting a three-dimensional circuit structure. This structure can be combined with other electronic product designs to create a variety of different applications. Therefore, from this point of view, FPC and PCB are very different. Of course, the FPC can use the terminal connection method for line connection, but it can also use the flexible and rigid boards to avoid these connection mechanisms.
A single FPC can use the layout method to configure many rigid boards and connect them. This approach reduces the interference of connectors and terminals, which can improve signal quality and product reliability.
For PCB, unless the circuit is made into a three-dimensional form by filling film glue, the circuit board is generally flat. Therefore, to make full use of the three-dimensional space, FPC is a good solution. As far as rigid PCBs are concerned, the current common space extension solution is to use slots and add interface cards, but FPC can make a similar structure with a transfer design, and the directional design is also more flexible. Using a connecting FPC, two rigid boards can be connected into a parallel circuit system, and can also be turned into any angle to adapt to different product shape designs.
What is the difference between FPC and rigid-flex PCB?
What is FPC? Flexible circuit board, is a printed circuit board with high reliability and high flexibility made of polyimide or polyester film. FPC has the characteristics of high wiring density, light weight, and thin thickness. It is a highly reliable and excellent flexible printed circuit board. It can be freely bent, wound, and folded, and can be arranged arbitrarily according to the requirements of space layout, and can be moved and stretched arbitrarily in three-dimensional space, so as to achieve the integration of component assembly and wire connection.
What is a rigid-flex PCB? The rigid-flex PCB is a special circuit board made by pressing a rigid circuit board and a flexible circuit board. The board materials used are mainly FR4 and polyimide. The rigid-flex PCB combines the advantages of the rigid characteristics of the rigid PCBs and the bendable characteristics of the FPC, so that the PCB is no longer a flat layer of two-dimensional space, but a three-dimensional internal connection and arbitrary bending and folding.
It can replace the composite printed circuit board connected by multiple connectors, multiple cables and ribbon cables, and has the advantages of making the product stronger in performance, higher in stability, lighter in weight and smaller in size.
The biggest difference between the FPC and the rigid-flex PCB is that the FPC can be bent freely, while the rigid-flex PCB can be bent only in the flexible area, and the cost of the rigid-flex PCB is much higher than that of the FPC. The production process of rigid-flex PCB is much more complicated than that of FPC, and of course the manufacturing difficulty is also a little more difficult.
Rigid-flex PCB has both the characteristics of FPC and PCB. Therefore, it can be used in some products with special requirements. It has both a certain flexible area and a certain rigid area, which is of great help to save the internal space of the product, reduce the volume of the finished product and improve the performance of the product.
What are the constituent materials of FPC?
FPC is one of the popular circuit board types to meet the needs of flexible electronic circuits. Designed to replace traditional wire harnesses, FPC can meet a variety of complex electronic designs. Although the performance of FPC depends on many factors, the main material plays a key role in it. So, what are the constituent materials of the FPC? In the structure of the FPC, the constituent materials are composed of flexible copper clad laminate (FCCL), cover film, adhesive film and so on.
Flexible Copper Clad Laminate (FCCL): Common sheet films of flexible copper clad laminates include polyimide film (PI), polyester (PET), polyethylene naphthalate (PEN), liquid crystal display polymer ( LCP) and other polymer material plastic films. In FPC, the copper clad laminate mainly plays the role of three levels of conductivity, insulation layer and support point.
Cover film: It is composed of chemical plastic film and adhesive. The function of the cover film is to protect the conductive part of the flexible circuit that has been completed. It has different sheet film and adhesive types and thickness specifications.
Adhesive film: It is formed by pouring adhesive on both sides or one side of a substrate film. There are also adhesive films with a pure adhesive layer without a substrate. The adhesive film has different adhesive types and thickness specifications. Adhesive film is used for interlayer bonding and insulation of multilayer boards.
Ordinary FPC is mainly composed of two materials: base material + cover film. The base material is mainly composed of PI or PET + glue + copper. PI is a polyimide insulating resin material, which is characterized by high temperature resistance and good bending performance. PET is polyester insulating resin material, but its characteristics are just opposite to PI, so it is used by few FPC manufacturers.
What is the difference between the base material, cover film and PI reinforcement of FPC?
FPC is a highly reliable and excellent flexible printed circuit board made of PI polyimide or polyester film, with high wiring density, light weight, thin thickness and good bendability. As a special engineering material, PI has been widely used in aviation, aerospace, microelectronics, nanometer, liquid crystal, separation membrane, laser and other fields.
The long-term use temperature is -200℃~426℃. PI polyimide is very common in FPC, it exists in the base material, cover film, and even reinforcement. Some people may be confused about this, so today let’s discuss what is the difference among them?
The difference between the base material, cover film and PI reinforcement of FPC in function:
1. PI substrate: For FPC substrates, there are two types: adhesive substrates and non-adhesive substrates. Regardless of whether it is an adhesive substrate or an adhesive-free substrate, PI polyimide is essential.
2. PI cover film: its main function is for circuit insulation.
3. PI reinforcement: often applied to the area on the back of the FPC gold finger. The PI ribs are used to increase the thickness and hardness of the fingers for easy insertion and removal.
The difference between the base material and cover film of FPC in thickness:
1. PI substrate: For PI in the substrate, 1/2mil and 1mil are very common, and its thickness can even reach 4mil and 5mil (DuPont non-adhesive PI material).
2. PI cover film: There are two options for the thickness of PI on the cover film, 1/2mil or 1mil.
3. PI reinforcement: The thickness of PI reinforcement can be selected according to customer needs, such as 0.075mm, 0.1mm, 0.125mm, 0.15mm, 0.175mm, 0.2mm, 0.225mm, 0.25mm, etc.
The difference between the base material and cover film of FPC in color selection:
1. PI substrate: no color choice.
2. PI cover film: PI cover film has three colors of yellow, white and black.
3. PI reinforcement: It changes with the thickness, the thicker the darker the color. For example, 0.075mm PI reinforcement looks brown, and 0.25mm PI reinforcement is closer to black.
FPC is a printed circuit made of flexible insulating substrates, which has many advantages that rigid printed circuit boards do not have. It can be bent, wound, and folded freely, and can be arranged arbitrarily according to the requirements of the space layout, and can be moved and stretched arbitrarily in the three-dimensional space, so as to achieve the integration of component assembly and wire connection.
The use of FPC can greatly reduce the volume and weight of electronic products, and it is suitable for the development of electronic products in the direction of high density, miniaturization and high reliability.
Therefore, FPC has been widely used in aerospace, military, mobile communications, laptop computers, computer peripherals, PDA, digital cameras and other fields or products; FPC also has good heat dissipation and solderability, and is easy to assemble and connect.
Application advantages and development prospects of FPC
With the upgrading of electronic products, FPC caters to the development trend of light, thin, short and small electronic products by virtue of its unique advantages, and plays an important cornerstone role in the field of electronic information industry. FPC is mainly used in the connection of electronic products. It exists as a signal transmission medium and has high reliability and excellent flexibility. With the continuous advancement of informatization and intelligent construction, the market demand for FPC will also increase.
The demand for FPC in the electronics industry is on the rise. On the one hand, due to the excellent characteristics of FPC, FPC is very suitable for the ultra-thin requirements of electronic products. On the other hand, in the high-frequency and high-speed transmission of the circuit, the reliability requirements for the FPC are relatively high. Therefore, the market size of FPC in the electronics industry is constantly expanding. The advantages of the FPC are that the wiring and assembly density are high, and the connection of redundant cables can be omitted.
The application fields of FPC can be divided into three categories: smartphones, wearable devices, and automotive electronics. The application on smartphones covers battery modules, display modules, touch modules, camera FPCs, connection modules, etc. A smartphone needs to be equipped with 10-15 FPC. With the commercialization of 5G, the development of smart phones towards miniaturization and large screens, and the rise of folding screen mobile phones, etc., will increase the amount of FPC. The demand for FPC in the field of smartphones is on the rise.
In addition to mobile phones, the automotive electronics market is also the main battlefield of FPC. For automotive control systems, such as instrument panel display, air quality, audio, display, sensors, etc., the requirements for high signal transmission and high reliability make FPC begin to show its advantages. With the emergence of electronic products, the market and use of FPC have also expanded, and the upgrading of different types of electronic products will bring more considerable development prospects than the traditional market.
Considerations when choosing an FPC manufacturer
Once the FPC is designed, it needs to be manufactured. That means you need a professional FPC manufacturer. Choosing the right FPC manufacturer is critical to the long-term success of your project. A good choice can make your job easier, but a bad choice can lead to a lot of trouble. Before you start, you need to make sure you choose the right FPC manufacturer. So, what are the considerations you should pay attention to when choosing an FPC company?
Here are some questions you need to ask before choosing an FPC manufacturer:
1. What are the specifications of my FPC , can the manufacturer meet it?
2. Is the FPC manufacturer a professional proofing, small batch or batch processor?
3. Does the FPC quality meet my requirements?
4. Can I form a relationship with a supplier?
5. Can my FPC budget cost meet the manufacturer’s quotation?
6. How fast can the FPC manufacturer deliver the products?
When evaluating an FPC manufacturer, the first question you need to ask is can they meet the design and fabrication requirements of your product? This process will include some pretty standard questions such as:
1. Can their production process produce the FPC that I need?
2. Do they have the materials you need in stock?
3. Can they manufacture the products according to the required tolerances?
As for how to choose a suitable FPC company, you can click to learn more. If your FPC project involves some non-standard requirements, then you may need an experienced professional manufacturer to deal with similar specifications. Most FPC manufacturers will list the production process scope and technical capabilities on their websites. If you have any special requirements about FPC, you may wish to contact us directly.
What are the factors of FPC processing cost?
Although the PCB has some common basic processes, the most important thing is to determine different production processes according to the thickness and material of the substrate, the accuracy requirements of line width and line spacing, the design structure and production scale, and other special requirements specified by customers. The process and equipment lead to a great difference in the cost of making FPC.
FPC is a product with a high degree of customization, and there are many components that will affect the cost of FPC. For new buyers of electronics manufacturers, it is necessary to understand all factors about the cost of FPC before making samples.
The production process of FPC is relatively complicated, and usually has more than 40 processes such as circuit inner layer production, exposure, pressing, drilling, and electroplating. Although FPC has strong customization characteristics, these most basic processes are necessary.
In the cost structure of FPC, direct material costs usually account for about 60%, direct labor costs usually account for about 15%, and manufacturing costs usually account for about 25%. However, copper-clad laminate enterprises in the direct cost have a strong right to speak, so the cost reduction of FPC manufacturers is mainly achieved by reducing manufacturing and labor costs.
The reduction of manufacturing costs is mainly achieved through automation to improve production efficiency and yield, and reduce labor costs mainly through the transfer to the Midwest to achieve.
Based on the above factors, when we are prototyping FPC, it is not that the smaller the quantity, the cheaper the price. There are many factors that FPC manufacturers consider when quoting. Past experience shows that the higher the quality requirements for FPC, the higher the cost.
For details, you can click and contact us to have a better understanding.
Flexible printed circuit boards, also known as “FPC boards”, are printed circuit boards made of flexible insulating substrates.
In the structure of the FPC, the constituent materials are composed of flexible copper clad laminate (FCCL), cover film, adhesive film and so on.
The biggest difference between the FPC and the rigid-flex PCB is that the FPC can be bent freely, while the rigid-flex PCB can be bent only in the flexible area, and the cost of the rigid-flex PCB is much higher than that of the FPC.
