What are the different stages of PCB design, testing, and manufacturing?

A printed circuit board (PCB) provides the mechanical foundation, electrical interconnections, and signal routing for electronic devices and systems (Figure 1). By enabling compact, reliable, and high-performance circuit integration, PCBs support various industrial, medical, and consumer applications in data centers and at the intelligent edge.

Figure 1. A PCB with multiple integrated circuits (ICs), passive components, and interconnections that enable high-performance electronic systems. (Image: Sonic Manufacturing Technologies)

This article discusses the three pillars of effective PCB design and production, exploring the initial design phase and explaining how fabrication transforms PCB designs into physical boards. It also highlights the placing and soldering of components in PCB assembly, the verification of functionality and reliability during PCB testing, and key design and manufacturing considerations that span the entire process.

Three pillars of efficient PCB design and production

As shown in Figure 2, electronic engineers typically focus on three key priorities throughout the PCB design and production stages.

Figure 2. Electronic engineers must balance three key priorities to achieve optimized PCB design and production. (Image: Siemens EDA)

Layout solvability: addresses complex packaging challenges, confirming components are optimally placed and routed within design parameters.
Performance: ensures signal integrity, power distribution, and thermal management meet electrical and reliability requirements.
Manufacturability: integrates design for manufacturability (DFM), design for assembly (DFA), and design for testability (DFT) processes to maximize PCB manufacturing yields and minimize production costs.

Notably, checklists play a critical role in verifying compliance throughout PCB design and assembly. The checklist’s contents span internal guidelines to industry standards such as Institute for Printed Circuits (IPC) specifications, supplier-provided requirements, and customer-defined criteria.

Exploring the PCB design phase

The PCB design phase defines customer requirements, establishes a foundation for reliability, and forms the basis of an initial checklist. Engineers assess key system-level electrical parameters, such as current limits, operating voltages, signal types, and capacitance constraints. Additional considerations cover impedance characteristics, shielding requirements, and major circuit component selection.

The mechanical input stage defines physical features, such as board outlines, mounting and tooling holes, slots, cavities, and component locations. Engineers also identify keep-ins, keep-outs, and height restrictions to ensure mechanical compatibility. Afterward, as shown in Figure 3, they perform schematic verification to confirm that the circuit design matches the intended functionality and logic.

Figure 3. A PCB schematic created using EDA tools, representing circuit components and interconnections essential for logical design. (Image: EMA Design Automation)

A design rule check (DRC) then uses EDA tools to validate trace widths, spacing, clearances, and other critical constraints against design requirements.

Subsequent design stage checks include:

Component placement: optimizes layout for signal integrity, thermal performance, and manufacturability. Proper placement reduces noise, improves heat dissipation, and simplifies assembly.
Signal integrity analysis: simulates high-speed and RF signals to mitigate crosstalk, reflections, and electromagnetic interference (EMI). Proper signal routing ensures all traces reference a continuous ground plane to minimize noise.
Power distribution network (PDN): verifies power and ground layer coupling, decoupling capacitor placement, and low-impedance power delivery. Balancing power integrity with signal routing involves tradeoffs, requiring thorough analysis to maintain design intent.
DFM analysis: verifies compliance with industry standards and best practices to maximize yield and minimize production costs. Key manufacturability constraints include minimum trace widths via structures and solder mask clearances.

How fabrication transforms PCB designs into physical boards

The fabrication stage transforms PCB designs into physical boards. Engineers first verify Gerber file accuracy, ensuring proper layer alignment, drill file integrity, and overall design consistency. They then document specifications to ensure the manufacturing process matches design intent and requirements.

Additional fabrication stage checks span:

Layer registration: confirms precise alignment of multilayer stacks to prevent misregistration, which can lead to connectivity failures or impedance inconsistencies.
Material quality: ensures the PCB substrate meets required thermal and electrical performance specifications, such as dielectric constant, loss tangent, and coefficient of thermal expansion.
Solder mask and surface finish: verifies uniform solder mask application and consistent surface finish, including hot air solder leveling (HASL) and electroless nickel immersion gold (ENIG). This protects exposed copper, prevents oxidation, and confirms reliable solderability.
Via quality: checks that vias are properly plated and, if required, filled to maintain robust interlayer electrical connections and mechanical reliability, reducing the risk of open circuits or premature failure.

Placing and soldering components during PCB assembly

As shown in Figure 4, one of the first steps in PCB assembly is solder paste deposition, where automated machinery applies solder paste onto designated pads before component placement and soldering.

Figure 4. Automated machinery deposits solder paste onto the PCB. (Image: Hillaman Curtis)

Once this stage is complete, engineers place and solder components onto the fabricated board, verifying orientation and ensuring proper alignment of polarized components such as diodes, capacitors, and ICs. They also inspect solder joint integrity, confirming joints are smooth, shiny, and free of cracks, voids, or bridging.

Additional assembly stage checks cover:

Pick-and-place accuracy: ensures automated assembly machines precisely position components on designated pads, preventing misalignment that could impact electrical performance or manufacturability.
Thermal profiling: optimizes the reflow soldering process to prevent thermal damage to components while ensuring strong, reliable solder joints.
Cleaning and coating: removes flux residues, and if required, a conformal coating is applied to protect the board from moisture, dust, and environmental contaminants that could degrade performance.

Verifying functionality and reliability with PCB testing

Testing confirms the assembled PCB meets all functional and reliability requirements, whether using flying probe or bed-of-nails methodologies. Electrical testing evaluates continuity and isolation, verifying proper connections and the absence of shorts to prevent unintended signal paths. Functional testing then confirms the PCB operates as intended under normal conditions, assessing power distribution, signal integrity, and component interactions.

Additional testing protocols include:

Boundary scan testing: uses the Joint Test Action Group (JTAG) standard to diagnose connectivity issues in inaccessible pins and verify IC functionality without physical test probes.
Environmental testing: subjects the PCB to temperature cycling, vibration, and humidity exposure to evaluate durability and long-term reliability under real-world conditions.
In-circuit testing (ICT): analyzes individual components and their electrical connections within the assembled board, identifying faulty solder joints, missing components, or incorrect values.

Additional design and manufacturing pointers

Comprehensive documentation and close collaboration with external suppliers are essential throughout PCB design and production. Documentation encompasses schematics, bills of materials (BOMs), fabrication drawings, assembly instructions, and test procedures. Each document must be accurate, up-to-date, and aligned with the intended design. Compliance with industry standards — such as IPC-2221 for design, IPC-A-600 for fabrication, and IPC-A-610 for assembly — ensures quality and consistency across the PCB lifecycle.

Summary

PCBs provide electronic systems’ mechanical foundation, electrical interconnections, and signal routing backbone. They support consumer, medical, and industrial applications across data centers and the intelligent edge. To optimize design and production, engineers prioritize layout solvability, performance, and manufacturability at every stage.