AB161 LUXEON N Application Brief 20170315 ©2017 Lumileds Holding B.V. All rights reserved.

21

In some instances, the new peeling location is not wide enough. In such cases, the peeling location needs to be widened so

that the cover tape can be peeled off without any obstruction (see Figure 25).

Figure 25. The cover tape peeling location in this feeder needs to be widened so that

the cover tape can be peeled off without any obstruction.

To minimize the jerking of components in pneumatic feeders during indexing, it may be necessary to install an air pressure

control valve. In some pneumatic feeder designs, such a control valve is already integrated by the machine supplier; in

others, an external control valve may have to be installed (see Figure 26).

Figure 26. Pneumatic feeder with integrated air pressure control valve (left) and pneumatic feeder with

air pressure control valve installed afterwards (right).

4.4 Reflow

A standard SMT lead-free reflow profile can be used to reflow LUXEON emitter onto a PCB.

Things to watch for after reflow include:

1. Solder voids (see Figure 27) — perform x-ray inspection. It is desirable to keep the solder void to less than 25%

coverage of the pad area.

2. Any visible damage, tilt or misplacement of LUXEON emitters.

3. Change in color and/or reflectivity (i.e. dull appearance) of the solder mask. This may impact the light output

extraction or cause color shift.

4. Functional test (open/short).