A simple understanding of PCB and its composition
In the electronics industry, there is a key component called PCB (printed circuit board). This is a very basic component, which makes it difficult for many people to explain what a PCB is. This article will provide a detailed explanation of the composition of PCBs and some commonly used terms in the field of PCBs.
PCB (Printed circuit board) is the most common term, also known as “printed wiring boards” or “printed wiring cards”. Before the emergence of PCBs, circuits were composed of point-to-point wiring. The reliability of this method is very low because as the circuit ages, the rupture of the circuit can lead to an open circuit or short circuit at the circuit nodes.
Wire winding technology is a significant advancement in circuit technology, which improves the durability and replaceability of circuits by wrapping small diameter wires around pillars at connection points.
As the electronics industry evolves from vacuum tubes and relays to silicon semiconductors and integrated circuits, the size and price of electronic components are also decreasing. Electronic products are increasingly appearing in the consumer field, prompting manufacturers to search for smaller and more cost-effective solutions. So, PCB was born.
ComposiTIon
The PCB looks like a Dobos torte or Lasagna – layers of different materials are pressed together by heat and adhesive during fabrication.
Let’s start from the middle layer.
FR4
The substrate of PCBs is generally glass fiber. In most cases, the glass fiber substrate for PCBs generally refers to the material “FR4”. The solid material “FR4″ gives PCB hardness and thickness. In addition to FR4, there are flexible circuit boards produced on flexible high-temperature plastics (polyimide or similar).
You may find PCBs with different thicknesses; However, the thickness of most PCBs is 1.6mm (0.063 ”). Some products also use other thicknesses, such as using a plate thickness of 0.8mm.
Cheap PCBs and hole boards are made of materials such as epoxy resin or phenol, lacking the durability of FR4, but they are much cheaper. When welding things on this type of board, a strong odor will be smelled. This type of substrate is often used in low-end consumer goods. Phenolic substances have a lower thermal decomposition temperature, and excessive welding time can lead to their decomposition and carbonization, and emit unpleasant odors.
Copper foil
Next, we will introduce the thin copper foil layer, which is pressed onto the substrate by heat and Adhesive during production. On double-sided boards, copper foil is pressed onto both sides of the substrate. In some low-cost situations, copper foil may only be pressed on one side of the substrate. When we refer to “double-sided board” or “two-layer board”, we mean that there are two layers of copper foil on our Lasagna. Of course, in different PCB designs, the number of copper foil layers may be as small as one layer, or
