Owing to the increasingly complex designs of today’s technology, printed circuit boards have evolved into increasingly complex electronic structures. A printed circuit board today may consist of multiple layers or substrates.
This article will simplify a PCB into three types.
The simplest of printed circuit board designs is the single-sided board. This type of circuit board has only one layer of substrate. This means the design of the printed circuit board is simplified into two sides. The first side is where the printed circuit boards’ components are soldered on. The components are connected to the circuit board through their terminals which are soldered onto the substrate. This is to provide permanent connection between the transistors and the copper tracks of the circuit board. But in a single-sided board, the copper tracks are printed on the other side. To establish a connection with the transistors on the other side, there are vias or holes that are drilled through the circuit board. The vias allow the transistors to pass through the board and make direct contact with the copper tracks.
Another design type of printed circuit board is the double-sided board. This design still only has a single layer of substrate. However, instead of having a component side and copper track side, both sides of the single substrate are printed with copper tracks. Both sides can also house different components. The copper tracks printed on each side may or may not be connected to each other, depending on the intended design of the electronic circuit. Should the design require electric current to flow on both sides of the single substrate, vias can be integrated into the design of the circuit board.
Finally, the third type of printed circuit board is the multi-sided board. These circuit boards are used for more advanced and complex circuit designs wherein a number of electronic components are required. Because it is multi-layered, this design can accommodate a significantly higher component density. A multi-sided board has three or more sides with printed copper tracks. To achieve this, double-sided board designs are usually connected together to form multiple substrates. If the design requires the different sides of copper tracks to be connected together, vias may be integrated into the design. However, since some substrates and layers are not readily accessible because they are sandwiched between other substrates, microvias are used to form electronic connections.
Typical vias form a straight hole through all of the substrates. Microvias are not full vias though they allow connections between substrates. A blind via is a microvia that is accessible to the outermost substrate but terminates in-between substrates. On the other hand, a buried via is not accessible and cannot be seen as it is embedded between substrates and allows sandwiched copper sides to connect with each other.
Flexible and Flexi-Rigid Boards
Common printed circuit boards are usually made of glass with reinforced plastic or FR-4 glass epoxy. However, innovations in design and development have led to the creation of flexible and semi-flexible boards to suit a wide range of applications, like non-traditional and non-conventional product designs.
Basically, instead of being made with the rigid FR-4 glass epoxy, these new variations of printed circuit boards are made of conductor layers printed on dielectric film and or coverlay’s/semi flexible liquid photo imageable solder resist.
Without a doubt, these types of boards hold many advantages over rigid designs like lighter construction, smaller space, and reduced interconnecting problems. In addition, flexible and flexi-rigid designs are also cheaper to produce and can be molded to suit all sorts of designs.