Applying minute amounts of two-component adhesive to speaker components with high precision

As smartphones and wearable devices become smaller and more functional, the mounting space for acoustic components such as speakers and microphones is becoming increasingly narrow. However, the precision application of two-component adhesives used for vibration prevention and fixing applications poses the following challenges when using conventional dispensing technology:

• The application area is narrow and minute, making it difficult for the nozzle to reach
  The mounting area around the speaker has many curved surfaces and unevenness, making it difficult to approach the nozzle at the correct angle and position, which makes it easy for the coating to misalign or become uneven.
• The mixing ratio of the base agent and hardener is prone to variation.
  When the two liquids are supplied manually or by external mixing, slight fluctuations in temperature and discharge pressure can cause the mixing ratio to shift, leading to problems such as poor curing and insufficient adhesive strength.
• Mixed liquid was wasted
  Because the liquid was mixed in advance and then applied, excess liquid was produced and discarded, resulting in waste.
• The amount of coating is extremely small, making quantitative control difficult
  When the liquid amount reached the level of several milligrams, existing equipment showed large variations at the start of discharge, making it impossible to ensure coating stability and reproducibility.
• Defects are often discovered late, resulting in high rework costs.
  Poor adhesion was often discovered during post-assembly processes, leading to a decrease in overall yield and a significant increase in rework.

To address this issue, we introduced the eco-DUO series, a high-precision dispenser that can mix and dispense two liquids in real time, resulting in the following clear improvements:

• Enables precise application of minute amounts even in narrow areas
  The combination of a positive displacement dispenser and a precision control nozzle allows for continuous, stable application in the minimum range of a few milligrams. Pinpoint dispensing around the speaker is possible without being restricted by angle or posture.
• Highly accurate mixture ratio control within ±1%
  By controlling the volume of the two liquids separately and mixing them at a fixed ratio just before the nozzle, it is now possible to maintain the ideal mixture ratio without being affected by temperature or pressure.
• Improved coating stability and adhesive reliability
  The incidence of poor curing was significantly reduced, and the variation in adhesive strength and adhesive position was improved. Stable results were also obtained in strength tests after bonding.
• Improved yield and optimized manufacturing costs
  This eliminates the need for re-application and correction work, improving overall productivity, and also contributes to reducing quality control man-hours, leading to cost optimization.