Adhesive Detection on PCB Assembly

VS8 miniature photoelectric sensors ensure that adhesive dispensers create high-quality applications

The detection of the leading edge and glue during PCB assembly can be challenging due to limited space near the glue dispenser. Monitoring the fill level of the glue dispenser is not feasible, so any gaps or bubbles in the applied glue must be detected quickly to reduce wasted product and downtime. Learn how the VS8 miniature photoelectric sensor solves this challenge, ensuring quality even in the tightest spaces.

The electronics industry is composed of incredibly small products, and printed circuit boards (PCB) have numerous densely-populated components on them. These boards are typically assembled in areas with minimal space. Errors on PCBs are easy to miss if relying on manual assembly and inspections. There is also very little room on electronics applications for large automatic solutions. Systems with large sensors for inspection can quickly get in the way and slow down machine performance with excessive downtime.

Your Benefits

  • Reduced production downtime and enhanced quality assurance of PCBs due to sensor detection
  • Faster mounting of sensors in areas with restricted space
  • An indication of fill level errors in the glue dispenser without complex monitoring

  • VS8 miniature sensors detect both adhesives and trays

  • The VS8 is small enough to be installed on the head of the glue gun

  • Detecting the trays’ leading edges ensures that the PCBs are in the right position for glue application

For more complex components, soldering and adhesive can both be used to make the pieces sturdier. However, the adhesive station on PCB assembly presents unique challenges. 

Monitoring fill level in the glue dispenser is challenging because it is not realistic to install a sensor inside of the gun.  Still, proper glue application is essential, because bubbles or gaps in the adhesive can lead to significant problems when parts of the PCB are not secure or easily fall off during use. 

Small Height Changes Indicate Presence of Adhesive

The VS8 sensor is a background suppression photoelectric sensor that is small enough to be installed on the robotic arm directly above the power control boards. The VS8 sensors are positioned to aim at the boards on the line, where the robot applies the adhesive. The sensor is taught the original distance of each passing board and recognizes the very small distance change after the glue has been used, detecting the adhesive regardless of color. Any chattering on the sensor may indicate bubbles or gaps in the glue and may require a refill to perform correctly.

Adhesive detection of this nature is helpful because it allows solving issues immediately. In this scenario, an operator can minimize downtime by reapplying the glue or refilling the glue gun before the part moves onto a secondary station and the glue completely dries. Poorly placed glue could easily cause PCB components to fall apart and lead to an increase in scrapped product or recalls.

Simple Installation close to the Dispenser 

Printed circuit board assembly stations have limited space that can make mounting difficult. The VS8 is small enough to be installed on the head of the glue gun without sacrificing quality, and the sensor operates reliably at close range. The bracket is adjustable to 15 degrees in either direction to make mounting easy and versatile.

A pair of VS8 miniature sensors are also installed to detect the trays that hold the printed circuit boards. As the trays move on the conveyor, the VS8 sensors detect the leading edge to confirm that they are in the correct placement for glue application. This ensures that the glue is applied to the right areas on each PCB.

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