PCB Inspection2023-09-21T08:31:12+00:00

A Complete Guide to PCB Inspection and Quality Control

Printed circuit boards (PCBs) are the foundation of electronics. They provide the interconnections between components that allow devices to function. With electronics becoming more complex and PCBs more densely packed, quality control is crucial. This article will explore PCB inspection methods, stages, and best practices to ensure your boards meet the highest standards.

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    Automated Optical Inspection

    The automated optical inspection (AOI) ElectronicsTalk introduced has two types: in-line and off-line. The off-line AOI uses 5 million pix digital high-speed industrial camera and multiple light sources optional, ensure the quality of image shooting and high resolution. Besides, the minimum inspection chip can be 0201mm with customized PCB dimension. Using convenient offline programming software, ensure PCB picture taken in real-time and stored efficiently.

    pcb inspection page aoi machine pcb in line

    Solder Paste Inspection – SPI Machine

    The solder paste inspection (SPI) is a 3D ultra-high precision type of inspection machine. The accuracy in the X&Y axis is less than 10 microns and equal to 0.37 microns in the y-axis.

    Owning professional GPU image processing, the inspection speed is 0.35 second/FOV and the mark detection time is 1.3 seconds per piece, which massively improve the production capacity.

    Also, using the latest RGB and D-lighting technology, ensure the quality of image shooting. Equipped with dynamic and static warpage compensation systems, maximally reduce the PCB warpage.

    pcb inspection page spi machine 3d in line

     PCB X-ray

    Thanks to the imported high-quality hardware from Japan and Korea, the PCB X-ray owns a first-class inspection performance. First, the X-ray source is imported from the best company in the world, owning 5 microns of Focal spot size with a lifetime of 10000 hours.

    Second, equipped with the latest model of the detector, with a high resolution of 50 microns, fast readout, and no image lag, which is capable of producing a clear X-ray image. Additionally, the automatic calculation function of software, and speed adjustment with 5 axis linkage system, provide image-central support while tilting.

    PCB X-ray inspection Machine

    X-ray Counter

    The X-ray counter is used for counting the number of components by the X-ray penetration method. The X-ray tube used is the closed type with a focal spot size of 30 microns and a long-serving lift, maintenance-free. Also equipped with a high-resolution flat panel detector, a pixel size of 139 microns, and an effective area of 427x427mm. What’s more, an average reel counting speed of 10 seconds per tray with a 99.99% repeat accuracy.

    It owns AI deep learning algorithm, fully automatic and intelligent identity components, and applies algorithms. Lastly, with a cloud database used, all of the x-ray counters can be interconnected to the unique cloud database, easy for daily data upgrading and machine operation.

    X-ray component counter Machine

    What is PCB Inspection?

    PCB inspection is the process of verifying that printed circuit boards meet design specifications and are free of defects.

    It involves using automated and manual techniques to examine boards at multiple stages of production. The goals are early detection of flaws, process control, and confirming that assembled boards are ready for shipment.

    Investing in robust inspection protects product quality and reliability down the line.

    Why is PCB Inspection Important?

    Modern PCBs contain thousands of solder joints connecting hundreds of components. A single flawed joint or missing component can lead to field failures. PCB inspection finds these issues before products ship. Other reasons inspection is critical:

    • Catches assembly errors early when fixes are easier.
    • Provides quality feedback to improve fabrication and assembly processes.
    • Helps maintain customer satisfaction and brand reputation.
    • Reduces costs compared to discovering defects later in the product life-cycle.

    Overall, inspection gives confidence in the quality of completed boards before they are integrated into products. It is an essential part of risk reduction and operational excellence in electronics manufacturing.

    PCB Inspection Techniques and Methods

    There are a variety of manual and automated inspection techniques used at different production stages:

    Visual Inspection Manual visual inspection involves operators carefully examining boards and checking them against a list of common defects.

    It relies on the inspector’s eyesight and meticulousness. Visual inspection can catch flaws missed by automated systems. But it is labor-intensive and subject to human error.

    Automated Optical Inspection (AOI) AOI systems use cameras, lighting, and software to scan PCBs. They compare images to an electronic CAD file to identify any discrepancies or defects.

    AOI provides rapid, consistent, and comprehensive inspection superior to manual methods. It excels at finding tiny component flaws and deviations from design. Large production runs are where AOI provides the most value with throughput up to thousands of boards per hour.

    PCB X-Ray Inspection X-ray imaging penetrates boards to reveal defects like opens, shorts, missing components, or reversed polarity that optical systems cannot detect.

    It is especially useful for verifying multilayer boards where interior features are otherwise inaccessible. High-resolution X-ray images allow inspection of board sections such as dense component clusters or ball grid arrays (BGAs).

    Flying Probe Testing Flying probes use 4-12 movable test heads to make contact at various test points on bare boards.

    They check electrical connectivity, isolate shorts and opens, and validate component values. Flying probe testing verifies the electrical function of boards prior to population.

    Tests can include continuity between nodes, identifying incorrect resistances, and detecting insufficient isolation between circuits.

    When Should PCB Inspection be Performed?

    To ensure quality, inspection, and testing should be performed at multiple stages:

    Bare Board Inspection – On raw blank PCBs following fabrication to catch any manufacturing defects before components are mounted.

    Solder Paste Inspection – After solder paste is applied but prior to component placement. Verifies the paste deposition meets requirements to avoid soldering issues.

    Post-Solder Inspection – Done after components are mounted and soldered to the board. Confirms proper placement, solder joints, and polarity, and identifies any assembly defects.

    Each stage builds quality assurance. Bare board and solder paste inspection allow early process corrections. Post-solder inspection gives final approval before shipping populated boards.

    Key Factors for Effective PCB Inspection

    To make PCB inspection maximally effective, manufacturers should:

    • You can use automated and manual techniques. Automated techniques include optical, x-ray, and probe inspection, which are fast and thorough. On the other hand, we use manual visual methods to find small flaws that people might overlook.
    • Inspect early and often – Implementing inspection at multiple stages provides better process control compared to just the final inspection.
    • Focus on proactive prevention – Use inspection data to continuously improve fabrication and assembly rather than just reacting to defects.
    • Partner with experienced vendors – Trusted partners offer the right inspection equipment, software analytics, training, and support.
    • Make it a quality culture – Inspection should be built into the mindset of all employees, not just done right before shipping.

    Following these best practices allows PCB inspection to be a value-adding process rather than a bottleneck. Working closely with inspection experts and equipment partners ensures you have the capabilities to meet your quality goals.

    F.A.Qs About PCB Inspection

    What are some typical defects found during PCB inspection?2023-07-14T10:02:57+00:00
    Common defects include missing/misaligned components, insufficient solder, shorts, spills, solder balls/splashes, pad damage, nicks, improper polarity, and holes/cracks in boards.
    What is the difference between a visual inspection and AOI?2023-07-14T10:05:18+00:00
    Visual inspection relies on manual examination while AOI uses automated camera systems for scanning. AOI is much faster, more consistent, and can detect smaller defects. But visual inspection can sometimes catch flaws that automation misses.
    Can AOI detect defects on boards with conformal coating?2023-07-14T10:06:03+00:00
    Yes, the latest AOI systems can inspect coated boards. Advanced algorithms compensate for the coating material and still find defects under it.
    Does PCB inspection require special storage and handling?2023-07-14T10:06:41+00:00
    Boards should be protected from moisture, shock, and contamination which could later appear as defects. Handle boards by the edges and avoid touching component surfaces.
    What training or certifications should inspection personnel have?2023-07-14T10:07:40+00:00
    Inspectors should meet IPC certification requirements covering acceptance criteria, inspection methods, and common PCB flaws. Ongoing training ensures personnel keep pace with the latest standards.
    Does every PCB need to go through a full inspection process?2023-07-14T10:08:25+00:00
    For low-volume prototype runs, a sample-based approach may suffice. But for production boards, 100% inspection is advised to guarantee every board meets specifications.

    Learning Has No Limits

    ElectronicsTalk aware of this philosophy all the time, like the over 2 decades we are still serving countless individual for their PCB assebly business, check the guide we prepared here for PCB Inspection.

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    We help you avoid the pitfalls to deliver the quality and value your PCBA solutions, on-time and on-budget.

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