PCB vs PCBA: What’s the Difference?

PCB and PCBA are the two most common terms in the electronics industry. Although the difference between them is only one letter, they represent different things. The full name of PCB is Printed Circuit Board, which refers to a blank board without any electronic components assembled. PCBA stands for Printed Circuit Board Assembly, which refers to a board that is assembled with various components and can achieve certain functions. PCBA is built based on PCB. In this blog, we will introduce them separately and compare their differences in detail.

What Is a PCB?

PCB (printed circuit board) is a thin and flat board made of non-conductive materials that provide a base for the mechanical structure and electrical connectivity of electronic components. The non-conductive materials used for PCB substrates include fiberglass, epoxy resins, or other insulating materials, which allow the etching or printing of conductive copper pathways over their surface. These copper pathways are known as traces and they electrically link together various circuit board components that are soldered to the PCB. The key purpose of a printed circuit board is to act as a robust yet lightweight platform for organizing intricate circuitry by mounting electronic constituents in designated locations.

Types of Printed Circuit Boards

According to the number of conductive copper layers, it can be classified as:

Single-sided PCBs: As the name suggests, they have copper tracks on only one side of the insulating substrate. They are low cost and simple, used in basic circuits.

Double-sided PCBs: These have conductive tracks on both sides of the substrate. Allow for more complex interconnections between components versus single-sided.

Multilayer PCBs: Consist of multiple copper layers bonded together, allowing much denser and complex circuitry. Used in advanced electronics and allows high-speed signals.

Based on the different materials used, printed circuit boards can be categorized as metal PCB, fr4 PCB, ceramic PCB, and so on.

To know more knowledge about PCB types, further reading: How Many Types of PCB Are There

PCB Composition

PCB is composed of the following layers:

• Substrate Layer

It is often constructed from insulating materials such as FR-4 glass epoxy, ceramics, or composites, which serve as a structural foundation.

• Conductive Layer

The conductive layer consists of copper foil affixed to the substrate, which is then meticulously etched to create pathways and landing points for circuit interconnections.

• Solder Mask Layer

It is a protective epoxy-based coating that envelopes the surface of the PCB, leaving designated spots for attaching components and guarding against inadvertent short circuits.

• Silkscreen Layer

The silkscreen layer imparts essential component details, such as labels, logos, and board outlines, utilizing ink or paint, aiding in both assembly and the identification and resolution of issues.

What Is a PCBA?

A PCBA (printed circuit board assembly ) contains all the necessary electronic components that provide the functionality of the board. It consists of a printed circuit board, on which components like ICs, resistors, capacitors, transistors are soldered. Additional parts like connectors, buttons, LEDs may also be assembled. The leads of the electronic components are electrically and physically attached to the PCB’s contact pads and conductive tracks by melting solder to form a joint. Once all components are soldered to the board and it is tested for proper functionality, it is called a PCBA. PCBAs are an essential step in electronics manufacturing, designed and assembled by electronics manufacturing service companies before the final product is put together.

Different PCB Assembly Methods

Based on different assembly techniques, PCBA can be divided into 3 types:

• SMT PCBA

SMT (Surface Mount Technology) PCBA uses surface mount components that are soldered directly onto the surface of the PCB without any holes. Components are small, allow high density packing and make the board compact. This process is automated.

• THT PCBA

THT (Through Hole Technology) PCBAs use leaded components with pins that are inserted into holes drilled in the PCB. The protruding leads are soldered on the opposite side. Components with large sizes are assembled manually.

• Mixed-technology PCBAs

Mixed PCBAs use both SMT and THT components soldered onto the same PCB. Smaller surface mount parts are combined with larger through-hole parts needing mechanical strength. This takes advantage of both technologies on one board. Assembly involves both automated and manual soldering.

What’s the Difference between PCB and PCBA?

• Manufacturing Process

PCB fabrication revolves around crafting the bare circuit board itself, involving tasks like designing the board’s layout, etching copper traces, and adding insulating layers. This process is typically automated and marked by high precision. In contrast, PCBA takes the PCB as its starting point and proceeds to populate it with electronic components and connectors. PCBA can be a manual or automated assembly process, depending on the project’s scale and complexity.

• Components and Complexity

PCBs consist solely of the bare board with copper traces, without any electronic components populated on them. While PCBAs incorporate a range of electronic components assembled on the PCB through soldering. This transforms the bare board into a functional electronic system, with complexity ranging from simple assemblies to dense arrangements with many components and integrated circuits.

• Cost and Time Considerations

PCB fabrication is generally more cost-effective and time-efficient compared to PCB assembly. PCB costs are lower due to simpler design and material expenses. PCBA involves higher costs for components and labor-intensive assembly processes. Additionally, PCBA lead times are longer due to the component integration and extensive testing required.

Features	PCB	PCBA
Components	Bare board with copper traces	Includes various electronic components
Functionality	Provides a platform for components	Results in a functional electronic device
Manufacturing	Focus on creating the bare printed circuit board itself	takes the bare PCB foundation and builds upon it by adding electronic components.
Cost	Lower	Higher
Time	Short lead times	Longer lead times
Composition	substrate, conductive layer, drill holes, solder mask, silkscreen.	PCB, electronic components, solder connections

PCB vs PCBA: When to Use PCB? When to Use PCBA?

Determining whether to use a PCB or a fully assembled PCBA depends on your project needs and production approach. If you just need the foundational circuit board to build upon later, a bare PCB is likely suitable, allowing customization and component integration flexibility. However, if you want a ready-to-go electronic assembly without needing to source and solder components, a PCBA is preferable, as it saves development and assembly time. For simple DIY projects with few components that you want to choose yourself, bare PCBs offer prototyping flexibility. But for complex projects with tight timelines, PCBAs may be the best solution to accelerate development.

The decision also depends on production volume – PCBAs are ideal for mass production while bare PCBs make sense for low-volume prototyping. For DIY assembly of simple PCBAs, you can solder components onto custom designed PCBs. But for complex PCBAs, working with a professional PCBA manufacturer is recommended. If you’re seeking expert guidance on your next project or need assistance in choosing the right service between PCB and PCBA, don’t hesitate to contact us.