When we see the word "PCBA" in different websites, it more represents the concept of rigid PCBA. However, PCBA can refer to both rigid boards, flexible boards, and even HID PCBs. Facing the increasingly obvious characteristics of miniaturization of electronic products, FS Technology flexible PCBAs have gained huge popularity, because they can be shaped, bent, twisted and folded, which makes your electronic projects infinite possibilities. In the final purpose, we believe that whether it is rigid, flexible, or rigid-flex PCBA, they have the same effect on electronic products, that is, connecting various electrical and mechanical components together. In order to know which type of board we should use for our electronics project, we need to understand the steps in which they are made.
https://www.fs-pcba.com/
How to judge the use of rigid and flexible PCBA
In terms of the cost of electronic projects, the price of rigid PCBAs is usually lower than that of flexible circuit boards. What FS Technologies refers to as "usually" is when all the factors that make up the cost of a PCBA are the same. There are times when it is cheaper to use a flex board than a rigid PCBA. To get a really accurate picture of the total cost of ownership for turnkey assembly, there are many factors to consider. Flexible circuits can eliminate the need for components such as connectors, wire harnesses and other circuit boards. By removing these components from the design, material costs, labor and assembly costs, and scrap costs are reduced.
Laptops and desktop computers, audio keyboards, solid state drives, flat panel TVs and monitors, children's toys and other devices used in our lives usually use FS Technology rigid boards instead of flexible ones to meet reliability requirements. But don't think that flexible PCBAs are less valuable, they are widely used in GPS units, tablets, smart phones, cameras and wearable devices.
For more complex circuits, choosing a flexible PCBA is the wisest choice. Its control of three-dimensional space is unmatched by any other type of PCB. Of course, this does not affect its use in low-tech applications. Flexible boards are used in LED lights at shopping mall counters, which in some cases makes installation easier.
Some similarities and differences between rigid PCBA and flex circuit
When designing rigid PCBA projects, FS Technology will follow certain design rules that are required, such as minimum hole size, minimum space and trace width, minimum distance to board edge, copper and overall design thickness. The design requirements for rigid and flexible circuits actually have a lot in common. These common processes include:
Drilling of holes and through holes
plating
Optical Imaging and Development
Etching of copper traces, pads, contours and planes
By baking, to remove moisture from the PCB
Flexible circuit overlay
As the most professional turnkey PCBA assembly company in China, FS Technology uses circuit overlay or overlay process to encapsulate and protect the external circuits of flexible circuits. Cover films for flex circuits are similar to solder masks for rigid PCBs, but with one essence: cover films are more flexible. According to fs-pcba.com, "cover films are usually polyimide films coated with a thermoset adhesive. Film thickness Ranges from .0005" to .005", with .001" and .002" being the most common.
The polyimide and adhesive overlays are laminated using pressure and heat, where the heat helps the adhesive flow easily and fill any gaps between traces and pads; this prevents air entrapment between the layers. Again from fs-pcba.com: "Adhesive flow is necessary as it helps ensure complete surface contact and encapsulation. The adhesive will tend to bleed slightly around the opening shown in the image below. This bleed Extrusion is often referred to as "binder extrusion" and is actually an ideal phenomenon.
https://www.fs-pcba.com/manufacturing-pcb/
After the overlay lamination process is complete, use drilling, routing or laser cutting to make any component and/or feature openings. Etching cannot be used.
IPC Standards for Rigid and Flexible PCBs
IPC-2221A, Generic Standard for Printed Circuit Board Design
IPC-2223, Standard for Partitioned Design of Flexible Printed Circuit Boards
IPC-4101, Specification for Base Materials for Rigid and Multilayer Printed Circuit Boards
IPC-4202, Flexible Base Dielectrics for Flexible Printed Circuits
IPC-4203, Adhesive Coated Dielectric Films for Use as Covers for Flexible Printed Circuits and Flexible Adhesive Bonding Films
IPC-4204, Flexible Metal-Clad Dielectrics for Fabrication of Flexible Printed Circuits
IPC-6013, Qualification and Performance Specification for Flexible Printed Circuits
FS Technology's summary of rigid and flexible circuit boards
Although rigid PCBA and flexible PCBA have the same effect on electronic products, they only play the role of linking electronic components, but circuit boards are still an important part of electronic manufacturing. While most engineers use rigid and flex PCBs for the same electronics project, flex PCBA requires some extra rules due to its extra manufacturing process steps. Although rigid PCBAs appear to be lower cost, the total cost rather than the cost of a single board should be considered before evaluating the price of a circuit board.