Silicon and Ceramic Submounts for High Brightness Light Emitting Diodes

A global leader in Integrated Passive Devices (IPD), OnChip announced the ability to provide Silicon and Ceramic Carriers or Submounts for HB LED (High Brightness Light Emitting Diode) manufacturers. With major advantages of power savings, increased life expectancy and faster response time over traditional bulbs, HB LEDs are rapidly taking over many applications such as LCD backlighting, traffic lights, automotive lighting, camera flash and even standard lighting. HB LEDs are more efficient and longer lasting than both incandescent and CFLs.

HB LEDs are predominantly built with Indium Gallium Nitride (InGaN) technology. LEDs using InGaN come with several design challenges such as electrostatic discharge (ESD) sensitivity and package thermal coefficient of expansion (TCE) issues. InGaN chips are generally considered Class 1 devices and in many cases, a discharge of only 10 Volts can destroy such sensitive components. In comparison, static charge of up to 30,000 Volts is not uncommon and can be generated quite easily. Studies indicate that ESD damage to electronics and associated equipment is estimated at over $10 billion annually.

ESD-damaged LEDs can appear dim, dead, shorted, or have low Vf or Vr. TCE mismatch between the LED chip and the lead-frame or package is another significant reliability threat. OnChip addresses both problems with these new submount offerings. OnChip produces silicon and ceramic submount that serves as an inter-poser between the InGaN chip and the lead-frame. Submounts reduce the TCE mismatch, while providing ESD protection via integrated zener diodes. Ceramics are ideal for High Power LEDs and OnChip offers both Aluminum Oxide and Aluminum Nitride materials. The Company also provides miniature silicon ESD diodes that can be mounted alongside the LED chips. These ESD diodes are available both as flip chips - ESD0201 and as single-wire bond chips - ESD8x8. Submounts offer optical benefits as well. These devices contain solder bumps, enabling flip chip assembly of the LED chip. This approach eliminates shadows caused by wire-bonding. Furthermore, submounts offer a reflective metal surface which help direct the light in the desired direction.