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The Fundamental Reality of an AOI Seal
December 31, 1969 |Estimated reading time: 3 minutes
The trend toward smaller components in consumer and medical devices is creating a concern for accuracy and reliability. This potential for health and safety issues related to malfunctioning electronic devices may make a mandated AOI seal for electronics products a reality.
By Joseph Vilella
For many years, the SMT industry has had to deal with the need to deliver smaller components into very dense circuit boards. We have gone from placing 0805 and 0603 components, to placing 0402 and 0201 components in large quantities in less than a decade’s time. The future could bring even smaller components. This trend for smaller components and increasingly dense PCBs responds to the consumer’s need to have the maximum amount of power and performance in very compact electronic devices. Consumers enjoy the benefits of miniaturization in electronics products daily, such as cell phones with incredible operational performance, laptops that provide wireless connectivity and functionality, GPS in handheld devices and high-resolution images on compact flat-panel TVs. All of this intelligence and performance is packed into a very small piece of real estate.
There is no doubt that consumer products will continue to provide us with high functionality, efficiency, comfort and freedom. But that is not the extent of the impact of electronics on our lives. A large portion of these miniaturized electronic devices play a big role in our health and safety, such as electronics used in hospitals, by the armed forces, in space systems and by government agencies for their infrastructure and our public safety. Because health and safety are critical elements to consider when developing and producing a considerable segment of the electronic device market, it is essential to take all the steps necessary to build reliability and quality into their design and manufacturing. There is no doubt that design engineers are doing an outstanding job in relation to building the necessary performance into their designs. By and large, the products we use seem to work as advertised, when they work well. There are, however, many instances when the required product reliability and quality simply are not there because of bad designs and unavoidable inaccuracies related to placing miniature components onto PCBs during the SMT manufacturing process.
The physics of delivering 0402 and 0201 components into each site on the majority of PCBs accurately works against the process because of issues with weight and aerodynamics. The result is that about 80% of problems related to SMT placement occur before going into the oven, and depend on board complexity and speed of placement. Defects can occur in 6% to 10% of boards manufactured in an SMT line. I have witnessed cases where high-speed production lines making a single product could not achieve better than 65% first pass yield, even though they had top-of-the-line equipment. I have seen other cases where it was impossible to prevent at least one defect on every board due to extreme board complexities. Those poor first pass yields could have been prevented with the use of AOI, and future occurrences were prevented once AOI was implemented in these problem facilities.
Strategically placed AOI is powerful and will improve first pass yields and product quality dramatically in any SMT line. Modern AOI systems also have come a long way and can provide high performance if they are used as advertised, and their strengths and limitations clearly understood. The truth is that about 80% of SMT lines globally have not implemented AOI into their processes, and some of the products produced by those lines could create potential issues related to public health and safety.
Because of the possibility of potential health and safety issues related to malfunctioning electronic devices, a mandated AOI seal for electronics products may become a reality. The inaccuracies caused by the miniaturization of the SMT process will drive such regulations. The AOI seal must be reasonable and realistic, and if properly implemented, will ensure the consistent use of AOI to achieve the best reliability in SMT manufacturing. Several cases of poor product quality have hit the news in the last five years, and the public wants to insure that what they purchase works well most of the time - especially when it deals with their health and safety. An AOI seal would lead ultimately to an improvement in the quality of our lives.
Joseph Vilella, SMT process optimization consultant, may be contacted at (619) 884-8360; e-mail: joevilella@mac.com.