Printed Circuit Boards 101 – Basic Terms
A printed circuit board is a core component of today’s technology. Without it, there will be no smartphones, tablets, entertainment systems, appliances, and even computers. It enables a large amount of components to fit into a small form factor. Therefore, it is important to understand what it really is. There are several terms pertaining to printed circuit boards that the average person will not understand. So, this article lists down some important terminologies that should jump start one’s search for knowledge about printed circuit boards.
First – what is a printed circuit board?
A printed circuit board is a module that houses several minute components, enabling them to interconnect with each other. The components are attached or soldered onto the board and make contact with the electrical circuit that’s either imprinted or etched.
These are devices or micro devices that each serve specific functions within the board. Electronic components are generally classified into two: active components and passive components.
Active components are devices that need a source of energy to carry out their function. Different definitions of active components may add that active components can amplify power and signals that pass through them. A common example of active components are transistors.
On the other hand, passive components are those that can only allow power and signals to pass through them and cannot introduce power completely into the electronic circuit. Examples of passive components are capacitors and resistors.
The long protruding metal endings of electronic components are called terminals. Terminals are made of conductive materials (usually metal) and make direct contact with the electronic circuit. There may be two or more terminals in each component. Electronic components are attached to the circuit by soldering the terminals into the vias in the printed circuit board.
There are holes that populate the entire printed circuit board. These holes are called vias. Vias allow connections to be made between both sides of the board. They also allow components to be soldered into the board. There are special types of vias that are called microvias.
Whilst vias are holes that are punched through the entire printed circuit board, microvias are minute holes that may or may not be physically accessible. There are some circuit boards that have two or more layers. Microvias can be placed to make connections between sandwiched layers. A blind via is a microvia that is only accessible on one side of the board. It doesn’t go through the board and ends in a sandwiched layer. On the other hand, a buried via is a microvia that is sandwiched between layers and cannot be physically accessed.
Soldering is the process of attaching two metals together by melting their interconnecting parts and then applying solder or metal filling to firmly bond them.
Soldermask is a thin coating or varnish that is applied on the surface of the board. This coating is to prevent short circuiting the board when components are being soldered. While there are different colors of soldermasks today, the most used color is still green. This is why most printed circuit boards are green.
Printed circuit boards usually have white markings printed on them. These markings are called silkscreen or overlays. These markings contain valuable information pertaining to the board like where specific components should be placed, what position the components should be in, where the test points are, or even configuration instructions.
The tracks that are characteristic to every printed circuit board isn’t just for design. The tracks are there to provide connections between the different components in the board. Power, electronic signals, and the like travel through the electronic tracks to get to the components that need them to function. While copper is the most commonly used material in making these tracks, other super conductive materials may also be used like conductive ink or silver paste.
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