Datasheet

Solder Pad Design

Notes for Figure 2:

1. The drawing above shows the recommended solder pad layout on Printed Circuit Board (PCB).

2. Application Brief AB204 (to be released) provides extensive details for this layout. In addition, the .dwg les are available at www.lumileds.com.

Assembly Precautions

The LUXEON emitter package contains a silicone overcoat to protect the LED chip and extract the maximum amount

of light. As with most silicones used in LED optics, care must be taken to prevent any incompatible chemicals from

directly or indirectly reacting with the silicone.

The silicone overcoat used in the LUXEON emitter is gas permeable. Consequently, oxygen and volatile organic

compound (VOC) gas molecules can diuse into the silicone overcoat. VOCs may originate from adhesives, solder

uxes, conformal coating materials, potting materials and even some of the inks that are used to print the PCBs.

Some VOCs and chemicals react with silicone and produce discoloration and surface damage. Other VOCs do not

chemically react with the silicone material directly but diuse into the silicone and oxidize during the presence of

heat or light. Regardless of the physical mechanism, both cases may aect the total LED light output. Since silicone

permeability increases with temperature, more VOCs may diuse into and/or evaporate out from the silicone.

Please refer to AB203 for more details on VOCs and other incompatible chemicals.

Figure 2. Solder pad layout.