High Bright Light Emitting Diodes (HB LEDs) are one of the fastest growing technologies in the world. Industrial, aerospace, utilities and commercial organizations with needs for highly dependable lighting contribute a large part of the HB LED market growth. High reliability and high efficiency are top characteristics to meet when producing high yields of LED applications.
HB LED designs today require maximum thermal transfer to achieve performance specifications. Typically, gold/tin eutectic is assumed for component attach; however, due to the reflow times needed, this process can be more expensive when compared to more traditional conductive epoxy. A second disadvantage with gold/tin is an inability to perform rework. Recently, adhesive paste manufacturers have designed silver epoxies tailored specifically to replace gold/tin. These pastes tend to have thermal conductivity (W/m°K @25°C) of 20 to 40 compared to ~57 for Au/Sn. Traditional silver epoxies are generally 2-4.
Reaching performance and cost targets requires continuous improvements in LED devices and packaging to extract every possible lumen per watt. Both throughput and repeatability are key factors in high-yield production processes.
Since the introduction of automated die and wire bonders in the 1980s, equipment manufacturers and process engineers have been challenged to balance speed with repeatability. Today, automated die bonders can perform epoxy die attach at a rate of 1.5 to 4 thousand die per hour; and automated wire bonders can interconnect complex packages at speeds of more than 10 wires per second. The advantage of automation is speed and consistency. However, a major concern with high-speed automated microelectronic packaging is that if something in the assembly process is wrong, everything will be wrong. Having a tightly regulated process flow helps avoid the risk of building a large batch of rejected product in a short period of time.
To ensure time-to-market success in high-volume production, specific methods to achieve throughput and quality are required. Click here to learn more about strategies and methods 
necessary to achieve the ultimate goal of automated precision HB LED assembly—to blend the requirements of high-reliability and high-throughput to support high-volume commercial production.
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Jessica Sylvester
Marketing Communications
Palomar Technologies