S-Bond Joining of High Brightness LEDs

S-Bond active solder joining is emerging as an effective method to bond heat sinks to the back of High Brightness Light Emitting Diodes (HBLEDs). Active solders can wet and adhere to many of the thermally conductive ceramics (AlN, BeO, etc.) that are being used in HBLED’s and enable effective and thermally stable and conductive joints.

Figure 1. Shcematic of HBLED with Heat Sink
Figure 1. Shcematic of HBLED with Heat Sink

Light-emitting diodes (LEDs) are semiconductor light sources used as indicator lamps in many devices and are increasingly used for lighting. LEDs were introduced as a practical electronic components in 1962 and now many versions are available across the visible, ultraviolet, and infrared wavelengths, and with very high brightness.

LEDs are created by depositing two thin layers of materials onto a substrate, one with an excess of electrons and the other having “holes” and needing electrons to achieve a more stable state. When a potential is applied across the device, the electrons and holes move in the opposite directions. This causes light to be emitted with a wavelength and color determined by the energy released when the electrons and holes combine.

High-brightness LEDs (HBLED) are a more recent development made possible by special deposition techniques. Such HBLEBs can be driven at currents from hundreds of mA to more than an ampere, compared with the tens of mA for regular LEDs. Some can emit over a thousand lumens. Since overheating is destructive, the HBLEDs must be mounted on heat sinks to allow for heat dissipation and to prevent device failure. See Figure 1 above that shows the elements on a HBLED.

Figure 2. Picture of HBLED
Figure 2. Picture of HBLED

One HBLED can now replace an incandescent bulb in a flashlight, or be set in an array to form a powerful LED lamp. This opens up many new applications such as backlighting for displays, automotive lighting and new consumer products like flash for camera phones or compact projectors.

With the growing application of HBLED’s, the need for effective heat sink to device bonding increases. S-Bond active soldering processes offer one step, fluxless joining of these components without the need to preplate the ceramic with Ti, Ni, and/or Au. S-Bond can join directly to ceramics such as AlN and BeO heat sink substrates and then bond these heat sinks to copper and aluminum heat spreaders as indicated in Figure 2.

Contact us to see how S-Bond can be a solution for your HBLED joining requirements