color on the Molex connector of the LED # 2 near by the edge (Figure 3). The brownish color suggested the high
thermal existed within the LED Arrays.
Figure 3: Observation
Following in the analysis was an x-ray image taken on the LED array. The x-ray imaging is a part of the root
cause analysis mainly to understand the visual condition of the bonded wires that interconnects the LEDs from
chip-to-chip and chip-to-substrate. Any damage to these bond wires can cause a light output failure.
The following x-ray and decapsulation images show below reveal broken wires existed within the LED arrays. The
damage to the wire has caused an open circuit that interrupted the flow of current and resulted to no light output.
Note: Due to over etching the silicone during the decapsulation process, the chemical impacted the chips’
adhesion to the substrate causing the chips to be removed.