Flexible PCB, Meet Flexible Dispensing

5 Tips for Successful Flexible PCB Dispensing

The following guide includes essential factors that our applications engineers consider when setting up a flexible PCB application. Together, they add up to higher UPH.

1.   Limit part movement. Apply vacuum and clamp tooling to secure thin, flexible PCBs in place, minimizing movement and ensuring they lie flat throughout the dispensing process. If needed, localized vacuum or mechanical clamp fixturing can be applied to adjust for gaps or spacing between parts. If mechanical clamp fixturing is used, ensure that there is sufficient access to components.

   
   

2. Accurately identify and capture the fiducials. Accurate fiducials are critical for every dispensing application, but they are paramount in flexible PCB applications. If parts or Kapton tape are shiny, adjust the lighting to prevent glare and emphasize contrast areas when finding fiducials. Ensure that the vision system accurately locates fiducials on non-standard shapes or in situations where there is excessive part rotation. If parts are not laid out in the same orientation in the carrier, and you're considering using dual valve dispensing to improve UPH, put careful thought into this step to retain efficiencies. Varied part orientation will require more dual-axis and stop-and-go moves as the dispense heads adjust pitch and direction and move from part to part.
   

3. Use jetting as the dispensing method. Jetting and height sensing capabilities can overcome common flexible PCB dispensing challenges, including tight keep-out zones (KOZ), highly populated carriers with skewed parts, varied component height, and inconsistent part flatness. The added ability to tilt the jet in the x or y-axis can improve accuracy and yield by reducing wet out and allowing direct access to tight corners in and around small, densely packed components.
   

4. Select the optimal jet and hardware combination. Verify the maximum jetting frequency, accuracy, and actuator reliability when selecting a jet. From there, configure the jet with the ideal nozzle, seat, and poppet size to specify the shot size for your application and avoid KOZ encroachment. Each of these aspects has a significant impact on UPH and reliability outcomes.
   

5. Select the ideal fluid type and viscosity. Work with a fluid supplier to ensure the fluid you select results in the desired thickness and coverage for your underfill, stiffener reinforcement, or encapsulation (also called precise coating) process. In some cases, inconsistent coverage can occur if the fluid viscosity is too low.

Flexible PCB Dispensing Product Guide

The Vantage® and Forte® Series dispensing platforms offer excellent UPH advantages for flexible PCB applications, including patented* real-time skew correction, Canvas® fluid dispensing software with enhanced fiducial finding capabilities, dual IntelliJet® jetting, and high-jerk acceleration.

Real-Time Skew Correction

With real-time skew correction, shifted parts and varied component height won’t slow you down. The Vantage and Forte Series offer a dual-valve system equipped with patented real-time correction to automatically adjust for skewed parts and component height variation in the x, y, and z-axis. 

New Canvas Dispensing Software

The new and improved Fids-on-the-Fly software feature in ASYMTEK Canvas software uses an enhanced method to accurately capture fiducials when dual-axis diagonal and curved moves are necessary, common in flexible PCB applications. Older dispensing software technologies, in comparison, find fiducials based on the programming sequence, which is not ideal for flexible PCB applications. 

Dual IntelliJet Jetting

Vantage Series with dual-head IntelliJet jetting can easily dispense to parts that are laid out in varied orientations. How? Through dynamic pitch adjustment and the ability to move both dispense valves independently while employing patented real-time skew correction. Independent dual heads also make the Vantage an excellent choice for applications where parts become skewed to a greater extent.Forte Series with Forte MAX dual-valve hardware also lets you run two high-frequency IntelliJet Jetting Systems simultaneously with patented real-time skew correction. If you’re currently running an ASYMTEK Spectrum® ll dispensing platform, the Forte Series is a powerful step up to achieving improved flexible PCB dispensing UPH.If mechanical clamp fixturing is applied to manage gaps between parts, as mentioned above, we offer specially designed stinger nozzles for the IntelliJet jetting system to ensure access to components. 

High-Jerk Acceleration

The Vantage and Forte Series also offer high-jerk acceleration. How does this help improve UPH? Because flexible PCBs have irregular dispense patterns, and parts can move around, you’ll typically see more stop-and-go and acceleration and deceleration between the dispense and non-dispense moves. The higher jerk capability efficiently manages these motions to deliver more significant UPH gain.