Authored By:
Joshua J. Markle
Cree, Inc.
Transcript
The rapid growth of LEDs has created a shift in the Lighting Industry that has carried over to the SMT assembly line. With increased demand for the assembly of LED fixtures there has been an increase in the number of companies that have started their own SMT lines, as well as a significant number of contract manufacturers to meet this new demand.
The high-power LED, with its soft molded silicone or glass dome has been in use for only about 5 years and there is still a significant amount of pick and place process refinement required to ensure these components can be placed at high speed, accurately, repeatably, and with no damage.
This paper discusses some issues in the pick and place process for LEDs and presents a method to troubleshoot and resolve them. Most placement problems result from mis-picks.
Based upon current experience with LEDs, 4 problem areas are defined in a pyramid structure with the most significant and frequent causes on the bottom, to be addressed first. Starting with the most significant these are.
- Proper nozzle setup
- Feeder units
- Backside support to PCB
- Fine tuning
Detailed descriptions and suggested corrections and optimizations are presented for each of these problem areas. Based on the author's experiences the suggestions covered in this presentation should assist anyone experiencing issues with picking and placing LEDs on an automatic high-speed production line.
Summary
For the past few years there has been a shift in the Lighting Industry that has carried over to the surface mount technology assembly line. What is this shift you may ask? Well it is the LED revolution. This revolution or change in lighting has some very promising results already in practice and many more companies looking to implement the LED technology into their product portfolio's.
With a number of companies looking to expand their portfolio to include LED fixtures there has been an increase in the number of companies that have started their own SMT lines, as well as a significant number of contract manufacturers to meet this new industries demands. With this surge in the new style of lighting the manufacturers need the automated pick and place process to achieve the throughputs that are being forecasted; there has been a sudden increase of companies that have faced issues around the pick and place process with less than desirable results.
The automated pick and place systems have been used for high-speed, highly accurate placement of a wide range of electronic components. A major factor in the automated pick and place manufacturing for surface mount devices (SMDs) is that most of the components previously being placed have been in use since the1980s. These process parameters and speeds specified have been focused on a solid or hard epoxy molded, flat topside packages, like capacitors, resistors and integrated circuits.
Over the multitude of years since the inception of the automated pick and place system, the parameters used to control the equipment have been refined. Now that there is a new product in the industry; it may require some adjustments, Especially when LEDs with a glass or soft silicone molded dome are introduced. This presentation will discuss some issues in the pick and place process for LEDs and presents a method to troubleshoot and resolve these issues.
Conclusions
The suggestions covered in this presentation should assist anyone experiencing issues with picking and placing LEDs on an automated high-speed production line. The recommendations presented here have shown significant reductions in mis-picks as well as other component handling issues with automated systems. From my travels and multiple visits to contract manufacturers around the world, I have found that using the pyramid troubleshooting method helps reduce errors and operator interaction during the pick and place process.
The proper nozzle, feeding adjustments, backside support, and settings have been demonstrated in numerous situations to assist in making pick and place equipment perform at a high level with low attrition rates. The steps of the pyramid are not the only items that can cause errors, but the suggestions in this application note provide direction for use in the correction of some of the concerns with placing LEDs. Millions of LEDs are processed daily resulting in a wealth of knowledge being gained, so if you have questions please contact your pick and place manufacturer or visit www.Cree.com and search Pick and Place applications note for more information.
Initially Published in the IPC Proceedings
|
