Testing is essential for ensuring high-quality PCBs. By employing well-established protocols, testers can effectively identify design flaws and malfunctions. Even the absence of testability can reveal errors, although this poses its own challenges. Inability to debug boards and understand design intent limits the extent to which PCB quality can be confirmed.
At this stage, visual inspection becomes invaluable for process control engineers in troubleshooting manufacturing defects during production. Fabrication and assembly are complex multi-stage processes that offer numerous opportunities for deviations from acceptable board criteria. A contract manufacturer with extensive experience can leverage their expertise to identify and address poor outcomes in product development, thereby preventing such issues from occurring in the first place. An engineering-oriented CM will have robust systems and procedures to ensure the highest quality assembly for a design, while effectively mitigating common PCB quality issues.
Common PCB Manufacturing Issues and Solutions
|Not laid out for DFM
Incorrect land patterns
|Call with the manufacturer to set design rules and best practices for performance
|Poor, incorrect, or missing documentation
Legacy documentation where translation may or may not be available
|Draft new documentation from design files (revision)
Correct documentation to latest changes
Via barrel breakage
|Review all relevant design rules and layout to identify potential design rule conflicts
Review processes to ensure best practices are being followed
|Misplaced or misaligned components
Poor solder joints
|Observe solder profile for automated processes including pre-heat/cool down segments
|Untestable or unstable/unforeseen test results
|Calibrate test equipment
Check test procedures
PCB Quality Issues That Can Cause Headaches During Production
The production of electronics involves multiple stages that are interconnected but can be treated as separate disciplines. Inadequate organizational structure or communication can result in substandard outcomes, leading to various issues:
- Unapproved part substitutions: Shortages or long lead times may necessitate part substitutions. However, it is crucial to pre-approve and document these engineering change orders (ECOs) in relevant documentation such as the bill of materials (BOM) and schematic. Failing to obtain proper notification can lead to two scenarios: either the substituted part works without detection of the change, or the substitution performs inadequately. Testers may observe discrepancies in device speed, timing, and value tolerances, which can have unpredictable effects on PCB performance. Correcting, revising, and documenting these substitutions at a later stage requires significant time and financial resources.
- Solder defects: The quality of solder joints on the finished printed circuit board assembly (PCBA) is vital for system continuity and long-term reliability. Solder issues often arise with complex component package types, but insufficient control and monitoring of solder processes can also contribute. Quality testing and inspection processes are fundamental for assembly performance in any contract manufacturer. Therefore, poor solder quality may only be the visible manifestation of underlying issues.
- PCBA system integration: Proper handling and protective equipment are essential when integrating the PCBA with mechanical enclosures or other system assemblies. Failure to follow guidelines during integration can introduce functional problems to the board. Since these errors are typically associated with the system assembly, they cannot be diagnosed by the contract manufacturer or detected during manufacturing. Identifying and resolving these issues may involve navigating through multiple shops, resulting in lengthy delays.
- Cables and connectors: Mechanical interconnects between boards and other system components are prone to intermittent failures. Cables must adhere to minimum bend radii requirements to avoid wire stress or issues with plug-receptacle interfaces.
- Mechanical assembly: Several mechanical components cannot be adequately examined using standard electrical test processes. These include heatsinks, faceplates, standoffs, and connectors that may be incorrectly installed and undetected during standard testing and inspection procedures.
These oversights consume valuable time and budgets, potentially leading to production delays. However, contract manufacturers with established processes in place to mitigate PCB quality issues and implement thorough testing can offer higher levels of quality assurance.
Best Practices for Manufacturing Processes and Standards
Before entering into a production contract, design teams must have a comprehensive understanding of the capabilities and competencies of their chosen contract manufacturer (CM). The following list outlines the services that a high-quality PCB manufacturer should offer to avoid PCB quality issues:
- Component testing: A well-trained technical staff should be capable of validating component functionality through rigorous testing. Documented processes that outline the procedures for component substitutions, as well as guidelines for customer notifications and approvals, are essential to maintain design integrity.
- State-of-the-art soldering quality control (QC): Testing should be conducted both before and after the critical soldering step in PCB assembly. This includes utilizing automated optical testing and employing certified inspectors for electrical testing.
- Engineering expertise: A dedicated engineering staff should thoroughly review all design documents to create a specialized production plan. This expertise also extends to documenting work orders comprehensively and tracking all changes in a customer database to ensure alignment between manufacturing and documentation processes.
- Enclosure design and box build: A CM capable of integrating full system assembly possesses complete control over all assembly processes. By providing turnkey electronics assembly, they can avoid common issues associated with multi-supplier assemblies, such as electrostatic discharge resulting from moisture, dust, or debris.
Your CM Exemplifies Quality to Perfection
While each PCB production project is unique and unexpected challenges are inherent in iterative design, an experienced contract manufacturer possesses the expertise to effectively navigate and prevent common PCB quality issues. Through well-structured processes and stringent standards, the detection of defects becomes ingrained, ensuring the highest quality and reliability of printed circuit board assemblies (PCBAs) within the shortest possible timeframe.
Here at VSE, we are deeply committed to manufacturing electronics for our valued customers, and this commitment drives us to continually improve every aspect of our production. From fostering strong relationships with component manufacturers to upholding best practices for design reviews and handling engineering change requests, our reputation in the field of life-saving and life-changing devices has been built over four decades through our unwavering pursuit of unparalleled excellence in PCB assembly.