AB178 LUXEON UV U Line Application Brief 20170620 ©2017 Lumileds Holding B.V. All rights reserved.

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b. Evaluate pick and place machine with electric controlled feeder rather than pneumatic controlled feeder for

better controllability.

c. Evaluate indexing with smaller pitch (for e.g. 2mm versus 4mm pitch) in pneumatic based feeder to minimize

poor pick-up process, as shown in Figure 11.

Figure 11. An example of Samsung SM421 feeder with 2mm (preferred) and 4mm indexing pitches.

3.5 Reflow Accuracy

Using the solder resist and stencil pattern layout as shown in Figure 5, LUXEON UV U Line’s compact and lightweight

construction can self-align during reflow as long as the two pads are in contact with their respective solder paste.

4. Packaging Considerations—Chemical Compatibility

The LUXEON UV U Line package does not have any silicone overcoat or overmold unlike most other LED packages.

However due to the nature of the short wavelength emission spectrum (violet and UV), it emits high-energy light which

can cause photo-thermal chemical degradation of polymeric materials. It is a good practice to keep the LED chip surface

clean of any foreign contaminants. For example, if there is a solder flux residue on top of the LED chip, it may leave a burnt

(brown/black) mark on the chip which can affect the total light output of the LUXEON UV U Line emitter and increase the

LED chip temperature.

RoHS

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