Chapter 11: Packaging (click on figure for full-size image)

Fig. 11.1. Typical packages; (a) LED with hemi- spherical encapsulant; (b) LEDs with cylindrical and rectangular encapsu- lant. Fig. 11.2. Cross section through high-power package. The heatsink slug can be soldered to a printed circuit board for efficient heat removal. This package is called Barracuda package which was introduced by Lumileds Corp. (adopted from Krames, 2003).
Fig. 11.3. (a) High-power package; (b) LED die in package; (c) package on printed circuit board with high thermal conductivity. ((a) after Krames, 2003; (b), (c) after after LED Museum, 2003). Fig. 11.4. (a) Electrostatic discharge (ESD) protection circuits using multiple pn junctions or Zener diodes. (b) ESD protection incorporated in Si submount.
Fig. 11.5. Thermal resistance of LED packages: (a) 5mm (b) low-profile (c) low-profile with extended lead frame (d) heatsink slug (e) heatsink slug mounted on printed circuit board (PCB). (adopted from Arik et al., 2002). Fig. 11.6. Chemical structures of polymers. Epoxy resins, silicone polymers, and poly methyl methacrylate (PMMA) are used as LED encapsulants. In the silicone structure, X and Y represent atoms or molecules such as H, CH3 (methyl), C6H5 (phenyl).