Laser marking of LEDs for back-light applications

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Rofin has revealed details of tests in the application area of LED back-lighting using its PowerLine E-12 SHG IC laser source (532nm wavelength) configured with twin marking heads. The LEDs used for LCD back-lighting are very small, and must be produced quickly in order to be cost-effective. The company states that the laser marking process for this application is extremely demanding, requiring a 0.080mm character height, 0.035mm line widths, exact positioning and marking speeds of more than 1000 characters per second. Engraving is performed within a tiny area, and often on white plastic housings. Rofin claims that its strengths include real-time compensation of position tolerances, which is an indispensable part of a reliable production process. The PowerLine E series lasers are said to offer efficient operation and ease of integration.

The markings produced by Rofin's systems are in response to increasing market demand for product traceability. High-power LED production usually requires traceability markings on GaN, sapphire, SiC or GaAs wafers with OCR or T7 data matrix codes. Rofin’s Waferlase systems are designed to meet requirements for wafer marking, assuring traceability of the manufacturing process for fault analysis of semiconductor devices. The systems all produce marks that are machine-readable, have no negative influence on subsequent manufacturing operations and still permit clear identification at the end of the process chain.

The PowerLine E-12 SHG IC laser is used to engrave tiny 2D matrix codes, made up of spots which are just 0.043mm diameter, on lead-frames during the LED production process. Rofin‘s PowerLine E-30 SHG IC laser marks the white ceramics used as a substrate for LEDs, with characters just 0.15mm high and line widths of 0.020mm and ECC200 data matrix codes which have a 1mm edge length.