In simplest terms, flexible circuitry is a grid of conductive paths that connects on a flexible substrate. So, it is a solution for packaging your electronics projects. It is also known as flexible printed circuits, flex circuits, flexible circuits, and flexible PCBs.
You can also think of flexible circuitry as a printed circuit board that can bend. However, there are main differences between them while designing and fabricating them. You cannot use the same rules as you use while creating a PCB layout.
Inflexible circuitry, a dielectric layer, connects with a metallic coating of traces. Copper is a popular choice for conductive material. However, it can get oxidized easily, so solder or gold are often used to protect it. And, polyester or polyimide is mostly for the dielectric layer. Figure 1 shows the details on a flexible printed circuit board.
Why do You Need it?
It would help if you had it to fulfill your requirements for a flexible circuit board. You would need them when you are looking for reliability and durability. Don’t worry if you don’t know where you can use such boards. Let us help you with that.
You can use flexible circuitry in many different areas. You can use them in antennas, laptops, cell phones, and LCD televisions. You can even use them in the aviation field. That is not it; they are also popular in calculators, cameras, hearing aids, satellites, and printers.
In this section, we defined flexible circuitry and its usage. In the next section, we will tell you about the five basic types of flexible circuits.
Fundamental types of Flexible Circuitry
Flexible circuitry can be classified based on their size, configuration, and functionality. However, its circuits are known for one of the following classes.
Single-sided flexible printed circuit boards have a single layer of metal trace arranged on only one side of a dielectric layer. In other words, a flexible polyimide film bonds to a metallic copper sheet. After that, you would need to chemically etch the copper layer to develop your desired circuit pattern. Later, the polyimide dielectric layer bonds for environmental protection and insulation of the circuit.
Dual access Single-sided
Single-sided flexible circuitry with dual access manufactures in such a way that copper is accessible from both sides. Special laser techniques and processes skive open the dielectric layer to get dual access to the single conductive layer.
Double-sided flexible circuits have a single dielectric layer with metal layers on both of its sides. Conductive copper layers mostly affix to substrate film via metalized thru-holes. You can create trace patterns according to your requirements on both sides of the polyimide film. After that, you should connect it to two copper layers using plated through-holes.
Multi-layered flexible circuitry has many conductive layers that are encapsulated and separated by dielectric layers. Overall, it combines many complex double-sided or single-sided circuits in a multi-layer fashion. These multiple layers may or may not have laminations throughout its structure.
If you want to provide maximum flexibility to your design, continuous lamination may not be the best choice. If you are facing the following design challenges, then multi-layer circuits are your design solution.
1. Specific impedance requirements
2. Unavoidable crossovers
3. Elimination of crosstalk
4. High component density, and
5. Additional shielding.
‘We Go Where Others Will Not,’ you could think of multi-layer flexible circuitry like that.
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