Proper nozzle size selection
The nozzle diameter should be slightly larger than the LED’s light-emitting surface (colloid) but not exceed the LED chip size.
This prevents the nozzle from squeezing or compressing the LED lens, which could damage internal wires or the die itself.
Material and Tip Design
Use a soft rubber tip, semi-rigid materials such as POM, for the nozzle tip to create a secure vacuum grip without applying excessive mechanical force.
Material characteristics
. Silicone LED Adhesion Issue:
- Silicone has high stickiness. Soft rubber nozzles may cause:
Sticking Risk: LEDs may cling to the nozzle and fail to release.
Contamination: Rubber may shed particles during contact, polluting LEDs or the nozzle.
POM Solution:
POM has a smooth, low-friction surface and does not bond with silicone. It ensures clean release.
. Durability & Wear Resistance
Rubber Limitation:
Rubber wears out quickly under high-speed use.
Short lifespan: Frequent replacements raise costs.
Reduced performance: Worn tips lose sealing ability.
POM Advantage:
Highly wear-resistant and fatigue-proof, POM lasts longer and lowers maintenance needs.
. ESD Control
LED Sensitivity:
Many LEDs are static-sensitive and need anti-ESD tools.
POM Adaptability:
POM can be modified with antistatic agents. Rubber is harder to control and may pose ESD risks.
Accurate Nozzle dimension, Hardness, and Positioning
The nozzle height should be set so it just touches the LED pad without pushing down on the LED surface. Excessive downward movement can deform or break internal wiring, causing LED failure or flickering
- Challenge with Tiny LEDs:
Small LEDs (e.g., 0201, 01005) demand high nozzle precision. Rubber nozzles, being soft, deform easily at high speed, causing:
. Positioning errors – Deformation shifts the contact point with the LED.
. Poor sealing – Rubber can’t maintain a stable vacuum in micro nozzles, leading to leakage.
- Why POM works better:
POM has high hardness and rigidity, ensuring tight tolerances, accurate LED alignment, and reliable vacuum holding.
Cleanliness and Maintenance
The nozzle tip must be kept clean and free of particles to maintain proper vacuum suction and avoid scratching or contaminating the LED surface
Rubber Nozzle Cleaning Issue:
Rubber attracts dust and oil, making it hard to clean and reducing suction performance.
POM’s Easy-Clean Advantage:
POM is oil- and water-repellent. Dirt is easy to remove—ideal for cleanroom applications.
Process Parameter Adjustment
Placement force should be controlled and minimized (e.g., less than 2.0 N) to reduce mechanical stress on the LED during placement
The pick-up position and vacuum strength should be carefully calibrated during initial setup to ensure reliable, damage-free handling
Tape Removal and Handling
The LED should be removed from the tape pocket close to the pick-up point to prevent the LED from tipping inside the tape and being damaged by the nozzle
