What is the difference between PCB and PCBA

PCB and PCBA are commonly used terms in the electronics manufacturing industry. Although the two abbreviations differ only by one letter, their meanings are worlds apart, and practitioners not in the electronics industry may be ridiculed for improper use. What are the definitions of PCB & PCBA and what is the difference between PCBA and PCB? First, let’s take a quick look at their relationship by watching the YouTube video below.

Is it PCB or PCBA in electronic equipment?

This article uses a mobile phone as an example. We can first disassemble a mobile phone to reveal its different parts and its internal composition, which mainly includes the following accessories: an earpiece, speaker, microphone, battery, screen, keyboard, printed circuit board and various chips. These parts can be roughly divided into three categories based on their functions:

  • Transmitter: Chip
  • Transport Carrier: PCB
  • Releaser: Shell
Disassembled mobile phone picture

From the perspective of many electronic consumers, electronic products mainly rely on the internal chip to function, which is correct, but they mistakenly think that the entire green board is a chip. In many electronic products, the green board is one of the protagonists of this article: PCBA board. After disassembling the PCBA board, the PCB bare board and electronic components can be obtained. An integrated circuit (IC) or chip is a type of electronic PCBA component. Presumably, the reason we may confuse chips with PCB and PCBA is that chips are also called integrated circuits.

PCBA chip

Breaking down the PCBA assembly process may help you distinguish the three relationships. Engineers program the required functionality into the chip and then commission a PCBA company to manufacture and assemble the PCB. The circuit board obtained after the assembly is completed is the PCBA board. Therefore, the circuit boards in the electronic equipment sold on the market are called PCBA boards.

PCB vs PCBA: Comprehensive Comparison

After reading the above article, I believe that most people can now distinguish between PCB and PCBA. Below, we will give a comprehensive analysis and introduction of the two terms from a more professional perspective, so that you can better understand the difference between the two.

What is PCB?

PCB without components

Concept

As depicted in the diagram provided, PCB is an essential component of electronic circuits, devoid of any integrated electronic elements. It comprises several key elements, including the substrate, silk screen, solder mask, conductive layer, pads, and vias. These elements collectively contribute to the functionality and integrity of the PCB.

At the beginning of its invention, PCB was known as printed wiring board (PWB). To avoid unnecessary confusion/panic, PWB was renamed to printed circuit board, or PCB, because of their namesake with a toxic chemical.

Working Principle

PCB is the foundation of modern electronic devices as they are important electronic parts since they may serve as a support body for electronic components, and a carrier for the electrical connection of electronic parts. Almost all electronic devices contain PCBs, from electronic watches and calculators to computers, communication electronics and military weapon systems.

The bare PCB, in its standalone state, does not inherently possess any functional capabilities or roles. However, once electronic components are meticulously assembled onto the board, the intricate wiring within the PCB serves as a crucial foundation, acting as a carrier for the components and integrated circuits. It facilitates the essential electrical interconnections between these components, enabling the seamless operation of the overall electronic system.

Main Type

There are different types of circuit boards according to different classification situations. The following are five conventional ways of distinguishing PCBs:

  • Number of layers: Single-layer (Single-sided), Double-layer (Double-sided), Multi-layer PCB etc.
  • Flexibility: Flexible PCB, Rigid PCB, Rigid-flex PCB, etc.
  • Substrate material: Rogers, Aluminum, Ceramic, FR-4, etc.
  • Function: High Speed, HDI, High-Frequency, etc.
  • Application: Military Electronics, Aerospace, Consumer Electronics, Medical, etc.

The picture above shows the different types of bare PCBs produced by FS Technology. At this point, this concludes the content of “what is a PCB”. If you want to know more about what a PCB is, you can go to its dedicated page to view it.

What is PCBA?

Optical Fiber PCB Assembly

Concept

PCBA, an acronym for Printed Circuit Board Assembly, represents the meticulous process of integrating electronic components onto a bare PCB board through advanced assembly technologies such as SMT and THT. Consequently, the term PCBA board denotes a fully assembled circuit board that encompasses the integrated electronic components.

As the brain of many electronic products, the CPU undertakes all the signal transmission work, but it is inseparable from the control of the PCB because it cannot work independently. It is different from PCBs in that if the bare board is our body, then the PCBA circuit board is more like the neural network of the human body. As a practitioner in the PCBA industry, we have always believed that is the core of electronic equipment and the bearer of future technological development. This is due to the lifespan, operating speed, reliability and stability of consumer electronic products having the most direct relationship with the printed circuit.

Assembly Process

After the bare board is manufactured, it will enter the assembly workshop, and the PCB assembly process will be completed after SMT and THT processing.

  • SMT Assembly Process: Incoming Inspection → Silk Screen Solder Paste → Patch → Drying → Reflow Soldering → Cleaning → Inspection → Rework
  • THT Assembly Process: Incoming Inspection → Manual Insertion → Wave Soldering → Trim Pins → Repair Soldering → Cleaning → Functional Test → Rework

Price Drivers for PCBA

Compared with the cost of finished products, the cost of PCB assembly is more transparent and open. PCB Assembly Cost Driver = Material Sourcing (parts and bare boards) + Bare Board Manufacturing + PCB Assembly (SMT and THT) + PCB Test + Shipping Costs.

Comparison of PCBA and PCB

ComparisonPCBPCBA
ConceptualBare board without componentsProduct with both PCB and components
MissionsProvides the base for a program to run independently in a multiprogramming environmentCost-saving, good circuit performance, and heat dissipation for electronic products
Manufacturing ProcessFocuses on board manufacturingPrimarily focuses on board assembly
Manufacturing CostsRelatively simpler and lower in costInvolves various parts and processes, resulting in higher manufacturing costs
Packaging MethodsTypically vacuum packaging for bare boardsPackaging with compartments or anti-static packaging for PCBA boards

Combination of PCB and PCBA

pcb TO PCBA

After understanding the relationship between PCB and PCBA, we will take a double-layer PCB as a case example to help you understand the process from PCB to PCBA.

There are many electronic components in electronic products and these components are mounted on a circuit board. In order to make the circuit design more compact, electronic engineers usually use double-layer or multi-layer structures, that is, use more components in a smaller space. For this purpose, a designer may use as many SMD packages as he/she can so that a lot of components can be placed on both sides. If the designer faces any difficulty in routing, then he/she can cater to this problem using vias and/or shift to another available layer. This makes the designing process easier and more compact. 

Double-sided PCBs have clear plated holes for DIP components and plated pads for SMD packages, along with a component layout on both sides of the PCB. For soldering components with a DIP package, flux flows through the conductive-plated hole and fills it, holding the component pin which passes through that hole. For SMD PCBA, flux simply forms a conductive layer on the pin of the SMD component and conductive pad in the layout on the PCB and creates a path for current flow to create a circuit. After a tedious assembly process, the work from a double-layer PCB to a double-layer PCBA is over.

Double-sided and multilayer PCBA have many advantages and allow designers to build very complex circuits. It’s up to the circuit designer which components and packages he chooses for the circuit. It is most frequently prescribed to use at least a double-sided PCBA in designs to remain as simple and as compact as possible.

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