Linear application of silicone resin to flexible substrates achieves stable application in high-density areas

Small electronic devices such as smartphones and tablets require highly accurate liquid application to flexible printed circuit boards (FPCs). As these devices become smaller, the space between circuits on these boards becomes extremely narrow and they have a high-density mounting structure, which posed the following challenges to conventional equipment:

• It is difficult to control application in narrow spaces, and the line width is unstable.
  The nozzle was unable to fit into the gaps between the components, resulting in variations in line width, which led to poor insulation and reduced reliability of the contact points.
• Bleeding or dripping at the coating edge, uneven film thickness
  Even with low-viscosity silicone resin, if the discharge control is not stable, problems such as swelling at the end of the line or the liquid leaking into adjacent parts can easily occur.
• Increased burden of manual correction and inspection processes
  The high defect rate requires stronger inspections and re-coating, which leads toTakt delays, increased man-hours, and increased worker burdenA vicious cycle was born.
• Variability in product quality and reduced yield
  Variations in the coating state resulted in differences in performance even within the same product, raising concerns about the impact on reliability and user satisfaction.

By introducing the high-precision positive displacement dispenser “eco-PEN series” into this process, the above issues were greatly improved.

• Highly accurate discharge within ±1% ensures uniform line width and coating amount
  Volume control enables constant discharge, and sharp, stable coating lines can be formed without bulging or thinning at the start or end of the coating.
• Achieves stable, continuous application even in narrow areas
  The thin-diameter nozzle can be accurately inserted into the gaps between high-density components, enabling smooth, continuous application, which reduces spillage onto leads and wiring.
  When I tried using a jet dispenser, splashing occurred and caused problems. However, since I can apply it directly with a nozzle, the problem is gone.
• Reduced rework frequency and shorter takt time
  Eliminating coating variations has made re-coating almost unnecessary, reducing the burden on the inspection process and significantly improving the efficiency of the entire process.
• •Improved product reliability and appearance quality
  By ensuring uniformity in linearity and film thickness, stable electrical insulation and a uniform finished appearance were achieved, enabling a smooth transition to mass production.