The foundation of contemporary electronic
gadgets is made up of printed circuit boards (PCBs), which allow different
electronic components to integrate and function. PCBs are an essential
component of practically all contemporary electronics, including smartphones,
medical equipment, cars, and space exploration systems. The importance of PCBs,
their varieties, components, manufacturing processes, and their crucial
function in electrical devices will all be covered in this article.
Getting the Fundamentals of a PCB Right
Electronic components are supported mechanically and connected electrically by
a printed circuit board, or PCB. The PCB is soldered to the components, which
include resistors, capacitors, transistors, and microchips. Conductive traces
are used to provide the electrical connections between the components.
An electronic device's PCB ensures that every component functions as a whole by
acting as both a structural support and a channel for signal transfer. The PCB
plays a crucial function in every practical electronic device since it is
nearly impossible to manage the complex network of circuits and connections
without it.
PCB components
The following are the main parts that comprise a PCB:
Base Layer Substrate: Fibreglass, epoxy, and other insulating materials are
commonly used to make the substrate. It serves as the PCB's structural base.
PCBs are often made of FR4, a flame-resistant epoxy fibreglass laminate. The
board is made stronger and more stable by this material.
Conductive Traces (Copper Layer): Electrical signals are guided by conductive
traces, which are thin copper layers. Usually, a chemical procedure is used to
etch these traces into the copper layer. They establish connections between the
several PCB-mounted components.
Solder Mask: To avoid undesired solder
connections, a protective covering known as the solder mask is put to the PCB.
In addition to its usual green colour, this coating can also be red, blue, or
black. The copper traces are shielded from unintentional bridges during
soldering by the solder mask. Additionally, it shields the traces from external
elements like dust and moisture.
The silkscreen layer is a printed layer that typically has the PCB's component
identification, labels, and markings. These indications facilitate maintenance,
troubleshooting, and assembly. The silkscreen, which is placed over the solder
mask, usually employs white ink to indicate the positions of pins, components,
and other crucial details.
Different PCB types
Different types of PCBs are available based on the requirements and complexity
of the electronic application. Several of the most prevalent kinds are as
follows:
PCB with a single layer of conductive material (often copper) on one side of
the substrate is known as a single-sided PCB. The most basic kind of PCB is
this one, which is usually utilised in inexpensive applications such simple
consumer electronics. Because only one layer of components can be joined, it
works well with simpler designs.
A double-sided printed circuit board (PCB) features copper lines on both
substrate surfaces. The traces on the two sides are connected by vias, and
components can be installed on either side.
3. Multilayer PCB: Conductive copper is
layered in more than two layers on multilayer PCBs. These boards are made by
stacking copper foil and substrate layers one after the other, with insulating
layers in between. Vias that travel across the strata connect them. More
sophisticated gadgets like computers, cellphones, and medical equipment
frequently employ multilayer PCBs.
4. Flexible PCB: Because of their ability to bend or flex, flexible PCBs are
perfect for applications requiring the PCB to be folded into intricate forms or
where space is limited. Typically, flexible PCBs are constructed from materials
like polyimide, which preserves the board's electrical integrity while allowing
for flexibility.
Methods Used in PCB Manufacturing
Several phases are involved in the sometimes complicated PCB manufacturing process.
The general PCB manufacturing process is summarised as follows:
Step 1: Create
The schematic, which shows the electronic circuit and its connections, is where
PCB design starts. After the schematic is finished, the board design is made
using PCB layout software (such as Eagle, KiCad, or Altium Designer). The
design entails arranging components, specifying the PCB's layers, and routing
lines.
Step 2: Copper foil printing of the design
Following design completion, the PCB layout is moved onto a substrate covered
in copper. In order to expose the copper traces and create the pattern, a
photolithographic method is used, in which a UV light is shone over a
photosensitive material.
Etching in Step Three
Only the desired copper traces remain when the exposed copper is chemically
etched away. The electrical pathways that will link the components are made
using the remaining copper. The size and accuracy of the conductive traces are
determined by the etching procedure, which is crucial.
Step 4: Hole Drilling
The PCB is then drilled with holes to accept through-hole components and vias
(for multi-layer boards). High-speed drills are used for drilling, and the size
of the hole is dictated by the type of via needed or the lead size of the
component.
Plating is the fifth step.
To provide electrical connections between the various layers in multi-layer
PCBs, copper is plated into the vias.
Using the Solder Mask in Step Six
To shield the traces from corrosion and avoid solder bridges during assembly, a
layer of solder mask is placed to the PCB after it has been etched. A
photolithographic technique is used to apply the solder mask, leaving just the
areas where the components will be soldered exposed.
Step 7: The Silk Screening Process
Printing of the silkscreen layer comes after the solder mask. To facilitate
assembly and troubleshooting, component labels, reference designators, and
other marks are positioned here.
Step 8: Examination and Verification
The PCB is put through a number of tests after manufacturing to guarantee its
functioning and quality. Visual inspections, electrical tests, and occasionally
automated optical inspection (AOI) systems that search for flaws are all
included in this. Functional testing is carried out to make certain
Last Assembly
Electronic components are soldered onto the PCB following fabrication and
testing. Components are positioned on the surface and soldered using reflow
furnaces in the case of surface-mount technology (SMT). Leads are soldered on
the opposite side of the PCB after being inserted through it for through-hole
components.
PCB applications
PCBs are utilised in many different industries for a wide range of purposes.
PCBs are crucial in the following typical areas:
Consumer Electronics: Almost all consumer electronics, such as computers, game
consoles, televisions, tablets, cellphones, and household appliances, contain
PCBs.
vehicle: PCBs are utilised in sensors, control units, navigation systems, and
safety features like airbags and anti-lock brake systems (ABS) in the vehicle
sector.
Medical Devices: PCBs are found in devices such as pacemakers, diagnostic
tools, ultrasound machines, and hearing aids.
Telecommunications: PCBs are essential to the communication and signal processing
of telecommunications devices, ranging from base stations to cell phones.
PCBs are utilised in satellites, avionics, navigation systems, and military
communication equipment in the aerospace and defence industries.
Industrial Equipment: In the manufacturing and process industries, PCBs are
utilised in robotics, automation controls, and machinery.