See the Surface, Reveal Hidden Defects | Do3think PCB AVI Multiple Exposure Inspection Solution

What are the biggest challenges in PCB surface inspection?

Surface defects such as scratches, exposed copper, and contamination can often be detected under visible light. However, hidden defects such as substrate cracks and inner-layer trace anomalies lie below the surface and can easily go undetected with conventional imaging.

The challenge is becoming more pronounced as PCB traces become finer and board structures more complex, with diverse surface materials and a wider range of defect types. A single light source often struggles to detect both surface and subsurface defects.

At high production speeds, simultaneously detecting surface and subsurface defects remains one of the key challenges in PCB Automated Visual Inspection (AVI).

To address these challenges, Do3think has introduced a PCB AVI multiple exposure inspection solution that combines white-light and infrared (IR) illumination. The solution is built around the self-developed DXL16K12CT-H1NF 16K TDI true-color line scan camera. It integrates multiple exposure imaging technology to overcome the limitations of single-light-source inspection. This enables integrated detection of both surface and subsurface defects on PCBs.

White-Light and IR Multiple Exposure Imaging Expands Inspection Capabilities

Do3think’s PCB AVI inspection solution centers on a hardware-based multiple exposure imaging system. It combines high-brightness white-light and IR strobe light sources with a high-speed strobe controller. The system precisely controls alternating exposures under white and infrared light, capturing images under both light sources in real time.

The two light sources serve distinct roles, providing complementary inspection capabilities:

 ✅ White-Light Imaging: Focuses on the PCB surface to precisely detect defects such as scratches, exposed copper, uneven solder mask coverage, and incomplete markings.

 ✅ IR Imaging: Penetrates the PCB’s surface solder mask to reveal hidden defects, such as substrate cracks and inner-layer trace anomalies, that are difficult to detect with the naked eye or under white-light illumination.

(Actual Inspection Results)

Core Equipment Configuration

Industrial Camera: DXL16K12CT-H1NF Dual-Optical-Port 16K TDI True-Color Line Scan Camera

Lens: 0.7× High-Precision Line Scan Lens

Light: High-Intensity White Light and Infrared (IR) Light

Control System: High-Speed Strobe Controller

Motion Stage: Precision XY High-Speed Stage

Application Coverage: Visual Inspection of Multiple PCB Features and Defect Types

The solution enables imaging and inspection strategies for key PCB regions, including traces, pads, holes, solder mask, and characters, based on different defect characteristics.

Key inspection items include:

·  Trace Areas: Opens, shorts, nicks, burrs, and trace anomalies.

·  Pad Areas: Exposed copper, contamination, and other visual anomalies.

·  Hole Areas: Hole position deviations and visible defects.

·  Solder Mask Areas: Uneven solder mask coverage, scratches, and surface anomalies.

·  Character Areas: Incomplete or misaligned characters and other visible defects.

·  Material and Hidden Anomalies: Depending on IR imaging conditions, the solution helps identify defects such as certain substrate cracks and inner-layer trace anomalies.

Solution Benefits:

PCB technology is evolving rapidly, with high-density boards and thicker solder masks becoming increasingly common. Inspection using a single visible-light source alone is struggling to meet quality requirements.

Do3think’s PCB AVI multiple exposure inspection solution combines surface inspection and hidden subsurface defect detection in a single vision system. It eliminates the need for two separate camera systems, reducing equipment footprint and production line modification costs.

Combining the stable imaging performance of a 16K TDI true-color line scan camera with white-light and IR multiple exposure imaging technology, the solution balances inspection efficiency and defect detection rate. It helps PCB manufacturers reduce missed defects and customer complaints while delivering more comprehensive visual quality control.

See the Surface. Reveal Hidden Defects. PCB AVI Inspection, More Than One Way to See.