Designing an advanced packaging system for infrared scene projectors

Abstract

Over the past several years, our research group has created the world’s first infrared scene projector (IRSP) that uses infrared light emitting diodes (IRLEDs). This allows for the creation of higher brightness, resolution and framerate projectors to be used for infrared testing purposes. The new projectors are able to use larger hybrids containing more IRLEDs than ever before. However, adding more IRLEDs creates a heating issue. Each IRLED will create a set amount of heat by itself and even more when placed in an array with hundreds of thousands of other LEDs. The heat is generated by inefficiencies in the IRLEDs and compounded by the low thermal conductivity between the IRLEDs and the cold finger of the pour filled Dewar currently housing the IRLED array and flip-chip bonded Complimentary-Metal-Oxide-Semiconductor (CMOS) Read-In-Integrated-Circuit (RIIC). ☐ This heating issue led to the need for a new way of cooling the hybrid down to cryogenic temperatures by the use of a Dewar chamber. The chambers that are currently available on the market were no longer sufficient, creating the need for a custom redesign. This paper focuses on the thermal management problems created by the newest IRSPs and their resolutions through a custom Dewar chamber design and subsequent fabrication.