WelcoTM LED101: No Clean Solder Paste with Unique Self-Alignment Properties for the next-generation mini and micro-LED die attach

mini and micro LED

Exciting future products such as micro-LED displays for Extended Reality (XR) headsets, mobile or smart wearable displays, or automotive dashboards demand the further miniaturization of LED dies to enable higher resolution and contrast. This puts tremendous challenges on the assembly process of mini and micro-LED dies, including solder paste printing onto extremely small substrate pads, effective mass transfer of millions of LED dies onto the substrate, and achieving zero defects after die attach and reflow. Specially designed material solutions possessing novel features are needed to overcome these challenges.

WelcoTM LED101 SAC305 T6 paste is a state-of-the-art no-clean printing paste engineered for mini-LED and micro-LED attach or SiP applications. The paste is designed to be printed through stencil openings covering 2 or more substrate pads each and self-align to the pads after reflow without bridging. The LED101 solder paste also possesses high tackiness to facilitate the effective transfer of mini and micro-LED dies. The LED101 series uses only Heraeus Electronics proprietary WelcoTM powders to achieve low voids and high yield solder joints for customers’ ultra-fine pitch applications.

Key Features

  • Uses high-quality Welco™ Type 6 powders
  • No clean and halogen free chemistry
  • Self-alignment during reflow
  • Best-in-class low-voids performance
  • Better solder joint reliability than using pure flux
  • Long stencil life (≥8hr) & staging life (≥8hr)
  • High tackiness for effective mini and micro-LED die transfer process