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The use of AOI (automated optical inspection) systems with dual-lane configurations is increasing in high-speed PCB (printed-circuit board) assembly, due to the systems’ ability to double capacity in the same space without increasing the number of operators. Jean-Yves Gomez, CEO of Vi Technology, commented on how multilane AOI systems are helping to increase yields and speed in PCB inspection, and he explained that such systems are being considered for semiconductor applications as well.
Q: What does a dual-lane configuration in AOI machines bring to PCB inspection?
A: Today, PCB assembly is massively automated, and productivity is measured by the square meter. Dual-lane configurations have been used in SPI [solder-paste inspection] and pick-and-place inspection for a couple of years, although they are not yet widespread in PCB inspection.
Adding more lines to increase capacity would normally require more operators and more floor space. A dual-lane AOI configuration consists of two side-by-side, width-adjustable conveyors that can inspect PCB assemblies in each of the lanes. Aside from the extra lane, you may also add another camera. So, it requires the same floor space and the same number of operators as a single-lane AOI machine but doubles capacity. The other immediate benefit is an increase in speed of roughly 30%.
Dual-lane inspection also gives flexibility. Operators can work in parallel with two different products, each with a different set of inspection criteria. A large manufacturer could use both lanes to increase inspection volume for one product, while a small manufacturer could maximize space by using each lane for a different product.
Q: Is this technology also applicable to semiconductor inspection?
A: We’re getting requests from semiconductor companies for more complex inspection solutions. They are facing severe constraints in back-end inspection as IC package complexity rises. For example, the wire bonding in all of the multiple, stacked die in a cellphone baseband module must be verified. In some cellphone camera modules, the die contains actuators and lenses, so die cost can represent half of the module cost. It’s important to get 99% yield in the back end, so most of the time semiconductor companies use visual inspection. As many as 200 operators per shift may look at the die before it is packaged.
But defects are getting too small for the human eye to see accurately and quickly, even using microscopes. One semiconductor manufacturer has approached us about using a dual-lane configuration for inspecting two different camera modules, a 3-Mpixel module on one lane and a 5-Mpixel module on the other.
Q: What kinds of floor space constraints are manufacturers facing?
A: Especially in China, the cost of floor space is rising. All of those plants are clean rooms, and the cost per square meter is very high. One dual-lane AOI machine in 1 m² could replace 40 to 50 manual operators in 100 m² of a clean room.
Q: What other trends are affecting AOI throughput?
A: Multisegment conveyors can optimize dual-lane loading. For example, with very small boards, you can use them to pre-load a panel to save time. For very high-volume environments, we are investigating some quad-lane configurations created by placing dual-lane machines back to back.
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