The complete guide to understanding printed circuit board assembly

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Printed circuit board assembly is a board with a host of assembled electronic components.  The electronic components are often assembled to the board through the soldering process. The printed circuit board's existence isn’t natural. Rather, it’s often done by PCB Assembly Manufacturer through two major processes – PCB designing and prototype creation. The arrangement of either passive or active electronics thus takes place shortly after the board has been manufactured.


Printed Circuit Board Assembly is the backbone of several modern electronics gadgets. They often feature the assembly of two major classes of electronics namely:

Active electronic components

A board can’t work without electricity supply. To control the supply of electricity, active components are thus needed. This implies that active board electronic components are elements on the board that regulates the flow of electricity onboard. Notable examples of active electronic components are diodes, transistors, vacuum tubes and lots more.

Diodes are electrical devices that transmit electric current in one direction. They are composed of a semi-conductive material between two terminals. Also, transistors are three-terminal devices that regulate current or voltage flow and also act as a switch for signals of the electronic variety. One pertinent thing to note in the description of those two active components is that they both deal with an electric current. That’s an evident description of active electronic components description. If they are found missing on a printed circuit board, powering the board may be unrealistic.

Passive Electronic Components

Passive components are described as printed circuit board elements that lower the power of an input waveform. They ensure that output waves emanating from a circuit has lower power than the inputs.  In other words, these components have no power to control electric current by means of another electric signal. Basically , they perform a series of important functions ranging from energy storage, voltage changing, to current flow resistance and lots more.

Typical examples of these components include resistors, capacitors, inductors, transformer, and sensors. While both resistors and inductors create resistance in electricity flow and resist changes in current flows respectively, capacitors help the printed circuit board to store energy. Also, transformer and sensors are good for changing power voltage and converting stimuli such as heat, light, sound and electrical signals. All these elements are often integrated to help boards carry out their functions.


Before the passive and active electric components can be assembled on a printed circuit board, the following are needed.

  1. Printed Circuit Board
  2. Soldering materials including solder wire, solder paste, solder bar, solder balls for BGA, solder preforms (depending on the type of soldering to be done)
  3. Soldering flux
  4. Soldering equipment including a soldering station, wave soldering machine, SMT equipment, inspection, and testing equipment, etc.


These assembly methods include :

  • Surface mount technology
  • Plated through-hole technology
  • Electro-mechanical assembly

Surface Mount Assembly (SMT): This technique of PCBA has been in existence since the 1960s. It made its way through the 1980s until this current age. It’s a popular PCB assembly method. Surface Mount PCB Assembly is the industry norm for electronic assemblies and it’s rapidly growing in use with an ever-expanding electronics market. This method offers higher circuit densities with the electronic components become fixed at both sides through standard soldering techniques.

The surface-mount assembly technique focuses on three main areas which include the surface mount component, the printed circuit board, and the solder joint. This method is best deployed for components that neither have leads nor legs.

Plated through-hole technology (PTH): This technology was extensively used in PCB Assembly during the 70s and early 80s as a substitute for Point-To-Point constructions. Although the Surface Mount Technology has surpassed the THT as the leading technology for PCB Assembly, THT is still in use nowadays.

Components that have leads are much assembled through this method. Most times, the printed circuit boards assembled through PTH often come with drilled holes. The technology allows the inserted of leads into the drilled holes.

Electro-mechanical assembly: This method is also known as the box-build assembly method. Manufacturers using this assembly method often use looms, molded plastics, cable assembly, custom metalwork and lots more to assemble circuit boards with the electronic components.


There is no constant thing as change. Change is inevitable in human life and career. In the field of electrical and electronics, change is that one thing that keeps shaping the quality of electronic material and processes of their production. As research keeps increasing and electronics keeps evolving, the size of electronics also began to decrease and electronic items started to be compact.

Printed circuit boards are mostly responsible for such compactness. They are characterized by lines and pads which links various points to one another. This board type permits the routing of signals and power between physical devices. The solder on the board does various functions. which include the :

  • Creation of electrical connections between electronic components and PCB surface.
  • Working as a durable mechanical adhesive.

This board type is much like a layer of cake. It has interchanging layers of various materials. To make the layers a single object, they get laminated together with adhesives and heat.  Since the focus of this topic is to describe PCBA, such details won’t be given on the composition of PCB.

Earlier before the printed circuit board dominates the electronics manufacturing industry, relevant electronic components are arranged through point to point wiring techniques. As the boards are coupled into products and the product usages ages, short circuits and frequent failures at wire junctions become evident. That circumstance forms a major challenge on point-point wiring style on the circuit board. Hence, the printed circuit boards emerge.


PCBs continue to be an essential part of the electronics industry and are expected to see long term growth and long term demand will continue to increase market size. If you don’t have the time and resources to get your PCB assembly done, then you will  need the turnkey PCB assembly services

Any engineer intending to assemble electronic component on such board must be aware of some factors which are :

  • Type of Printed Circuit Board
  • type of electronic components
  • purpose of the circuit board.

Taking cognizance of those factors is a surefire way of putting the right peg in the right hole. Perhaps you need to further information about HDI rigid-flex, don’t hesitate to contact Hemeixin at This email address is being protected from spambots. You need JavaScript enabled to view it.. Do you need to know the market price for the product? Get a quote here:

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