The printed circuit board is one of the constructive elements of any modern electronic device. First of all it is intended for mechanical fixing and electrical connection of the components of electrical circuits of the electronic device.
Structurally, the printed circuit board is a plate made of dielectric material (in most cases, but it is also possible to use structures on an aluminum substrate to improve the heat dissipation) with electrical circuits formed on its surface and volume.
The development of printed circuit boards is a process of mechanical and electrical design. During the development of the printed circuit board, the electrical components are connected by conductive circuits, but the process of connecting the components is in fact one of the most recent stages of the board design and is usually denoted by the term PCB tracing.
Initially, it is required to conduct an analysis and the possibility of placing the components of the electrical circuit on the board surfaces in specified dimensions, which are usually determined by the design features of the entire product and in particular the product body.
At the end of the placement phase, the electrical elements are combined. In the process of connecting electrical components, it is necessary to take into account a number of parameters, such as the amperage, the impedance, the influence of neighboring electrical circuits, etc.
We live in an environment full of various electronic devices. But, usually, not everyone thinks about how they actually work. In fact, the heart of such a device is a combination of conductors installed on a plastic board(PCB). Thus, the PCB design and layout varies depending on what task it should perform. So let’s take a look at what it really is and how it makes all the devices work correctly.
The PCB is an abbreviation that stands for the Printed Circuit Board. The PCB is a piece of hardware: composite sheet which is made of layered textile fibers or fiberglass, which is a more durable, and polymeric bond topped by a thin layer of copper as a conductive material. The PCB serves as a base where the electronic and electrical components are securely set and connected. By the way, all those components are usually fastened by soldering them onto the board according to the printed circuit board layout design. For security purposes, the capacitors, transistors, and other relevant elements may be extended with the wire.
There exist three types of PCB depending on the number of available copper layers: single, double, and multi-sided boards. While single and double-sided obviously have one or two outer layers of conductive material, the multi-sided board means that it consists of not only outer covers but inner ones, too. However, the engineering specialists are not in favor of the latter type since there is a higher number of conductive tracks while it lacks space on the surface. In addition, the maintenance of such a board becomes more challenging or even almost impossible to perform.
The PCB design differs depending on the placement of vias that pass the connections between multiple copper layers. Moreover, it can be customized by etching the copper tracks or traces. It means that the conductive layer doesn’t necessarily fully stay. Still, the remaining copper traces are exposed to the air that may result in corrosion, consequently, malfunction. In order to prevent such an effect, the exposed areas are coated with the special solution that also serves as additional protection from solder shorts or unexpected electrical contact.
Any design process consists of a few or more stages of development. So the PCB board design is no exception. In particular, it starts with considering the purpose, what requirements it should fulfill, which components it will interfere with and the conditions it will work at. They help you to focus on the precise features and physical properties that influence the schematic. It must be highly accurate since the whole development process depends on it.
Materials that are used should guarantee that none of the incidents will appear since the peculiarity of such a device implies the dense allocation of electronics and current proximity. Thus, it’s important to analyze the voltage and current levels before the components are installed so it should be considered in the design of printed circuit boards. Besides, the selection of those components should be changed depending on their properties to resist a particular temperature, current, or others.
The copper layer thickness deserves special attention. It can be also specified in the printed circuit board design documentation as the total amount or its weight per area (usually, ounces per square foot). The most common is 1oz per 1sq.ft which is equal to 35 µm, or 2 oz per sq.ft which is equal to 70 µm. However, there exist other options that are less than 1 oz or more than 3 oz. The latter are called heavy copper and designed for a high level of current in order to dissipate the high temperature the conductor produces.
Documentation takes place, including the BOM(bill of materials), throughout the whole manufacturing process. All of them should contain all the necessary information for guiding and controlling the whole fabrication process. For example, there may be information about the batch volume, its value, contributors (designers and manufacturers), PCB design layout, its physical dimensions, reports, etc. Meanwhile, some of them should be flexible and can be adjusted according to the new input data.
The components selection is another quality influencer. Choosing important filling depends on almost the same variables as materials do. All the electronics should correspond to particular requirements of performance, temperature, and functions. And after installing them, each transistor, conductor, or whatever it is should be reviewed considering the neighboring components. If needed, some of them should be substituted or removed. In some cases, the printed circuit boards design may be absolutely changed. However, it appears quite rarely and often influences the final cost of the device significantly.
The particular assembly may require additional revision. For example, the kits that consume more than 10mW and are designed to conduct more than 10mA should have some upgrades in thermal or electrical insulation since they are treated as powerful ones.
Once all those variables are figured out, there starts the process of manufacturing the prototype with the custom PCB design. And it never ends until it successfully passes all the testing procedures. Otherwise, it is revised, reworked, and it’s subject to testing again. It is considered approved when it meets all the requirements that were defined right at the beginning.
So, as you might have noticed, there are slight differences in how PCB is designed and other products in the global scope.
The ready-to-go design of printed circuit board is not the only option. Of course, you can make the printed circuit board design by yourself. But if it is your first time, then you may need some recommendations. So here they are:
It’s highly likely that the first custom printed circuit board design will distantly resemble the product you wanted to achieve. It doesn’t mean that there’s something wrong with the design for manufacturing PCB, but you need more practice to make it more accurate.
Still, you may skip this step either. For example, if you are looking for a PCB design for manufacturing then you may need a PCB design service instead. Fortunately, Axonim is an expert PCB design company that can make it for you without any hustle.
Read in Russian: проектирование и конструирование электронных устройств