Types of PCBs

There are different types of printed circuit boards, they are classified into various types based on manufacturing processes, design specifications, application and project requirements such as medical, automotive, defense, and space. More complex designs based on consumers’ needs and requirements pave the way for manufacturing different types of PCBs. Before you pick a PCB, you must look for a few considerations like space required, stress handling, and mechanical and electrical stability. 

Types of PCBs.

1. Single sided PCBs
2. Double sided PCBs
3. Multilayer PCBs
4. Rigid PCBs
5. Flexible PCBs.

1. A single-sided PCB.

It is the most common type of printed circuit board. It has a single conductive copper layer above the substrate. The electrical components are soldered or placed on one side of the board, and the entire etched circuit is visible on the other. Since these boards only have one conducting layer, the conductive paths cannot intersect or overlap and hence take up a lot of space. As a result, these PCBs are suitable for low-density design requirements. Single-sided printed circuit boards (PCBs) are used for basic and low-cost electrical/electronic instruments such as calculators, power supplies, LED lighting boards, FM radios, timing circuits, and so on. Advantages of Single-Sided PCBs Cost-effective Easy to manufacture Suitable for low-density designs Easy to repair if in case something goes wrong Easy to design 

 

2. Double-Sided PCBs.   

A thin layer of conducting material, such as copper, is added to both the top and bottom sides of the board in a double-sided PCB. Holes in the circuit board allow metal parts to be connected from one side to the other. These PCBs connect the circuits on either side using one of two mounting methods, through-hole technology or surface mount technology.Through-hole technology entails installing lead components into pre-drilled holes on the circuit board, which are then soldered to pads on opposite sides. Surface mount technology entails the precise placement of electrical components on the surface of circuit boards. Double-sided PCBs are used in a variety of applications such as cell phone systems, power monitoring, test equipment, amplifiers, HVAC application, UPS system, and many more. Advantages of Double-Sided PCBs Reduced size which makes circuit compact Relatively lower cost More flexible Increased circuit density Suitable for advanced electronic systems.

3. Multi-Layer PCBs.

Multilayer PCBs have more than two copper layers. In general, any board featuring at least three conductive layers is included in this category. Multilayer PCBs are designed in a ‘sandwich’ fashion, with several double-sided conductive layers divided by an equal number of insulating material sheets. All of these must be bonded and laminated together under high pressures and temperatures to ensure that no air gaps exist and that the final PCB assembly is properly stable. Multi-layer PCBs are used in computers, laptops, mobile phones, tablets, medical equipment, GPS trackers, and many other more complex circuits and devices. 

4. Rigid PCBs.

As the name implies, a rigid PCB is a circuit board that cannot be twisted or folded. The board’s base material is a rigid substrate, which gives the board rigidity and strength. They are composed of multiple layers including a substrate layer, a copper layer, a solder mask layer, and a silk screen layer which are adhered together with adhesive and heat.Although some circuit boards are either single-sided, double-sided, or multi-layered, rigid PCBs may be any of these depending on the needs. However, once made, they cannot be modified or changed. Rigid PCBs are used in GPS equipment, computer, laptops, tablets, mobile phones, X-rays, heart monitors, CAT scans, MRI systems, temperature sensors, control tower instrumentation, etc. 

5. Flexible PCB.

Flexible printed circuits, also known as flex circuits, are sometimes regarded as a printed circuit board (PCB) that can bend, when in reality there are significant differences between PCB’s and flex circuits when it comes to design, fabrication and functionality. One common mistake that designers make is to design a flexible circuit using the same rules as a PCB. 

The word “printed” is somewhat of a misnomer as many of the manufacturing processes today use photo imaging or laser imaging as the pattern definition method rather than printing. A flexible printed circuit consists of a metallic layer of traces, usually copper, bonded to a dielectric layer, usually polyimide. Thickness of the metal layer can be very thin (<.0001″) to very thick (> .010″) and the dielectric thickness can vary from .0005″ to .010″. Often an adhesive is used to bond the metal to the substrate, but other types of bonding such as vapor deposition can be used to attach the metal. Because copper tends to readily oxidize, the exposed surfaces are often covered with a protective layer, gold or solder are the two most common materials because of their conductivity and environmental durability. 

For non-contact areas a dielectric material is used to protect the circuitry from oxidation or electrical shorting. The number of material combinations that could go into a flexible printed circuit are nearly endless; current, capacitance, chemical and mechanical resistance, temperature extremes and type of flexing are just some of the criteria that impacts the material selections that best meet the functional needs. An experienced All Flex design engineer takes the critical requirements into consideration when designing a circuit to meet your needs.