Rework of µLED Components

Finetech rework systems for R&D and production environments are capable of reworking smallest LED devices. A typical use case is reworking LED triplets (RGB) on modern displays. The Finetech rework cycle includes all required process steps, including de-soldering of the defect LED triplets and removal from the array, residual solder removal, applying new solder paste as well as the placement and soldering of the replacement LED triplets.

Main challenge is the safe removal of smallest components from the LED array without disturbing adjacent triplets due to misdirected thermal input. An approach is required that supports a balanced thermal input enabled by a quick and precise control of all process parameters.

 

 

Use Case - Rework of µLED Displays

Extremely small LEDs in large RGB arrays are typically found in big info screens or scoreboards. Ideally, RGB displays should be 100 % free from pixel errors. A total or partial failure of single color triplets can only be tolerated up to a certain degree. Multiple failures will result in visible picture errors which create viewer distraction. Large displays are comprised of several tens of millions of color triplets, however, because they are separated into relatively manageable modules, a rework process is possible.

A customer from Asia approached Finetech looking for a solution to replace partially or completely failed LED triplets with new ones. The task was to find a time-saving and operator-friendly method. Our recommended system was a manual FINEPLACER® pico rs rework system with hot air top and bottom heating. The LED modules were clamped into a flexible support and pre-heated up to a temperature limit below the melting point of the soldering joints. The actual energy impulse to melt the soldering joints was introduced using the system's hot air top heating.

Overview of rework steps

Complete removal of a LED triplet, including residual solder. A removal head is used that has been designed to pick up all three LED components at once.

After the process, only a thin layer of residual solder remains on the pads.

Fresh solder paste is applied onto the pads using a suitable transfer pin (stamping tool).

One by one, the single LED components are aligned to the pads and then placed into the solder paste.

Using the hot air top heating, all three LED components of the pixel are soldered simultaneously.

Recommended Systems

  • FINEPLACER® pico rs

For high-precision rework of µLED components, check out our FINEPLACER® pico rs. With exceptional thermal management capabilities, this system handles µLED devices, small passives down to 008004 as well as a wide range of SMD components (BGA, CSP, QFN etc.) in various shapes and dimensions.

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