The printed circuit board, PCB, plays a very important role in technology; in fact, it is the hardware part of many automatic and computer systems that also involve a wide variety of industries, from medical to aerospace to military. Therefore, it is essential to know at least the ABC’s or rather the PCB, whether you work in the electronics and/or related fields or are a student or hobbyist.
What is a printed circuit board? Let’s start
Definition:
A printed circuit board, in English “printed circuit board” (PCB) is that component, usually rigid (but flexible ones also exist) on which electrical and electronic components are mounted. The functions of a printed circuit board are to provide a mechanical type of support on which the components will rest and to allow the electrical connection between the various components by means of tracks or traces Of conductive material.
All the acronyms of the Printed
Let us begin by first starting our learning column by providing you with all the acronyms by which the PCBS, so you will never find yourself unprepared when faced with the myriad of terms you will encounter during everyday supplies:
- CS: is used to quickly indicate the circuit board, we usually find it as an abbreviation through e-mail or messages.
- PCB: as already explained in the definition, it is the international acronym and therefore the best known and most widely used in speech as well.
- PWB: “Printed Wiring Board“ which is the least known and used, emphasizes the subtle difference between the terms, in fact PCB emphasizes circuits made on a PCB, while PWB refers more to the board itself.
- PCBA: “Printed Circuit Board Assembly“ indicating a complete electronic circuit board, that is, consisting of a printed circuit board in which the electronic components are already soldered. As an end result you will have a ready-to-use final board also known as a postcard, which is certainly a less common name.
- MCPCB: “Metal Core Printed Circuit Board“ which identifies a new type of printed circuit board created to dissipate the considerable heat produced by power LEDs. Characterized by a main core made of aluminum or copper, metals with good thermal conductivity.
What does a printout consist of?
We will now point out the basic parts that, once designed and machined, form our PCBS, from the simplest to the most sophisticated.
In fact in the figure, as an example, we can see a very simple circuit in which two resistors are mounted in series, but even from such a simple design we have elements that it is essential to know, including:
- In light green the solder mask or also called solder mask. It is a thin layer of lacquer-like polymer that is usually applied to the copper traces of the printed circuit board for protection against oxidation and to prevent bridging between the pads of closely spaced solder during soldering using wave or reflow soldering processes, typical for most PCBs.
- In dark green represented the insulating substrate, which gives mechanical strength to the whole, can be made of bakelite (SRBP) or vetronite (FR4). Bakelite is a yellow/brown phenolic resin, while vetronite is a greenish, translucent epoxy glass. Bakelite was widely used in the past because of its low cost, while today it is increasingly being replaced by vetronite, which has excellent mechanical, thermal, and electrical properties.
- In brunocopper which is the conductor par excellence and is used to make electrical connections between various components.
- In gray the solder between the resistor rheophores (in the drawing in black) and the copper leads. Soldering is in fact the joining of two conductors by means of a third conductor, in this case tin, which is melted between the two conductors to be joined so that a junction is formed.
The different types of circuits
Again, as mentioned earlier, there are first of all rigid, flexible or rigid-flexible printed circuit boards-the differences lie in the compound and thickness of the insulating material from which the board is made.
Also, depending on the number of layers they can conduct, printed circuit boards are divided into single-sided, double-sided, and the multi-layers, starting from 4 layers, 6 layers, and even up to 30 or more layers, but adding 2 layers from time to time.
The layers, referred to earlier, are called layers. The two layers, on the other hand, that are on the outer faces of the pcb are called top and bottom layers.
For completeness, the inner layers that are not visible are called inner layers. In a rigid printed circuit board, the substrate, which is flat and of constant thickness, is characterized by the presence of solid insulation, composed of materials called base materials, which have flame-retardant characteristics.
Single-sided or Single Layer
Let us proceed by analyzing the least complex type of circuit board, which is the printed circuit board that is also used to be called single-sided (or single layer). A single-sided printed circuit board is identified when the copper tracks are arranged on only one side of the insulating base .
The figure above is precisely an example of a single-sided circuit, as you can see in fact the copper tracks are placed on the bottom face of the board which is called the “Bottom.” In it the soldering is done and for that reason it is also called “Solder Side” or more often referred to succinctly as “LS.”
Instead, the top face of the baseplate is called the “Top,” and because the components are located there, it is also called the “Component Side” or more quickly the “LC.“
Dual-face or Dual Layer
The second type we analyze is the printed circuit board, which is said to be double-sided (or dual layer) when copper tracks are placed on both faces of the insulating substrate:
As can be seen in the figure:
- Welds can be made in the Top, Bottom, or both.
- Metallized Holes are used to connect two tracks placed in the Top and Bottom, respectively.
In particular:
- Industrial ones are made by drilling holes in the substrate where the connection is to be made and depositing copper.
Multilayer or Multilayer
Finally, when two faces are not enough, 1, 2 or even more intermediate copper layers, invisible from the outside, can be added.
The printed circuit board made in this way is called multilayer.
That said, multilayer circuits allow the construction of very complex circuits, with the added advantage of being able to mount components with many pins, such as integrated circuits, very close together, which benefits miniaturization.
The connections between layers are made through metallized holes, shown in the figure at the end of the paragraph, sometimes blind, inside which rivets are inserted to make the inner tracks reachable from the outer surface. In fact, below you will find a miniaturization of the sectioned multilayer, in which the hole wall metallization on the three hole types is highlighted to indicate complexity, blind hole (1), buried hole (2) e through-hole (3):
They are PCBs that can only be made industrially, and the production costs usually dictate large series production. That is why we at Tekube are here to advise you, accompanying you from feasibility study through industrialization to delivery to your warehouse.
One printout at a time…
But let’s proceed one step at a time, even the most solid houses were built brick by brick.
In fact, now that we have laid the foundation as well as the groundwork on the basics of printed circuit boards, all that remains is to wish you an electrifying initial learning. Initial… Precisely because from this article onward one will be released weekly to delve deeper into the world of PCBs, and feed not only our thirst for knowledge but also the content of our #PCBlog.
In fact, we will delve into the stages of industrial fabrication through the technical characteristics of PCBs to assembly.
Don’t miss any information pill, follow our official page LinkedIn, you will then be part of our upcoming appointments to discover the many nuances of printed circuit boards.
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