Circuit board PCBA and PCBs are vital components in electronic components today. Although at first glance they may seem similar, there are various key differences among the two. Read on to learn more.
Table of Contents
What is a PCB?
PCBs are physical structures that connect electrical components via pads, conductive tracks, and various other features.
Laminated onto non-conductive substrates, the layer of copper is etched chemically and then processed to make the pads and traces that connect all the components.
PCBs provide electrical connections and mechanical structures to mounted components for simple electronics such as toys and complex electronic devices such as computers and smartphones.
An excellent PCB design is important for electronic products’ manufacturability, performance, and reliability.
PCB Composition
- Copper layers – a thin copper foil is laminated onto a substrate, plated, and etched to create the conductive components of PCBs, including vias, pads, and traces. There can be multilayer, single, and double boards.
- Substrate – this is the base material supporting the copper layers. A laminate such as fiberglass (FR-4), Teflon, ceramic, or other materials is used for flexible or high-frequency circuits.
- Solder mask – an epoxy-based layer coating the PCB to prevent solder bridges between pads and protect the copper from oxidation.
- The finish is a coating like nickel, tin, or gold over traces and pads to prevent corrosion and accommodate soldering.
- Silkscreen – this is a printed layer for labeling components or connections.
- Drill holes are drilled through your PCB to enable mounting of components and vias in between layers.
- Edges may contain connections for putting into holes/slots or edge connectors for mounting.
- Vias – plated through holes providing connections between the copper layers.
The PCB Configuration
- Design – creating the circuit illustrations and layer via CAE/CAD software. Performs thermal and electrical simulation.
- Prototype – this is the initial production of the design boards for testing.
- Fabrication – the raw PCB substrates are copper coated, and the circuit configurations are moved onto them via photolithography. The copper that’s not wanted is carved away to leave just the wanted pads/traces.
- Soldering – the placed components and pads are applied with solder paste. The board passes through the reflow oven that melts the paste to solder components in position. Also, it may require automated assembly.
- Testing – perform quality testing, including ICT, functional testing, and visual inspection.
- Volume production – the circuit boards are produced in mass once engineers finalize the design and perform tests.
PCB Design Factors
- Routability of high-speed connections.
- Component placement accessibility.
- Number of layers to minimize crosstalk.
- Matching for traces and impedance control.
- Stiffness and mechanical mounting points.
- Thermal design to accommodate dissipation of heat.
What is a PCBA?
PCBAs take PCBs a notch higher by soldering electrical components onto your board. The PCB creates a connection and support structure while integrating real parts to create functional electronic circuits.
PCBAs Composition:
- PCB – the base circuit board mentioned previously, providing the base for assembling components.
- Components – all electronic and electrical components performing specific functions, including resistors, LEDs, capacitors, switches, connectors, and processors.
- Solder – the connections, solder paste, and joints that mechanically and electrically fasten the components to your PCB.
- Conformal coating – a protective insulation over the whole assembly.
- Enclosure – the case or box housing the PCBA and additional structural parts and hardware.
The PCBA bases its electrical personality on certain parts soldered onto it. You can populate the same design with various components for a number of applications.
PCBA Assembly Steps:
First, you are supposed to know that there are mainly two methods for assembling.
Surface mount – soldering of components onto the PCB surface without leads going through holes. It has a higher density, while assembly is more complicated.
Through hole – insertion of leads via holes in the PCB, then soldering on the opposite side to attach the components.
- Fabrication of PCB – produce the beginning PCB as previously described.
- Dispensing/Stencil – apply the solder paste at pad points on the board.
- Pick and position – a machine picks parts and then carefully positions them on appropriate pads.
- Reflow – here, the board passes in an oven that melts the solder paste to create joints and then permanently connect parts.
- Conformal coating – the whole assembly is covered with a thin layer in order to prevent shorting.
- Programming – programming of programmable components.
- Testing – functional, electrical, and burn-in testing.
- Final assembly – attaching hardware/heatsinks, mounting into enclosures, adding connectors, etc.
- Packaging – packaging and preparation for shipping.
PCBA Design Factors
- Selecting and sourcing of components.
- Cost optimization.
- Positioning for efficient assembly.
- Thermal design via heat shrinks.
- Coating coverage.
- Analysis of stress on solder joints.
Conclusion
There, you have all you need to know about the differences between PCB and PCBA, from the intended application in terms of functionality to design factors. In case you have any further queries, feel free to contact Cloom Tech.
