Evaluation Engineering - 21

ensuring high yield and quality output. More flex circuit suppliers are adopting these advanced flex manufacturing processing
techniques to enhance manufacturing efficiency and improve
yield while maintaining cost and market competitiveness. That's
where R2R manufacturing is making significant inroads.

R2R manufacturing can handle highly sophisticated flex PCB designs and offers inherent advantages by eliminating damage and
increasing the volume production of flex PCBs. Whereas sheetto-sheet processes are hindered by multistep batch-handling
procedures and small substrate sizes, R2R processing enables
the high-speed, continuous processing of a long flexible web,
producing tens of thousands of small FPCs in one long continuous production web. R2R can accommodate single- and
double-sided flex circuits, as well as the processing of the inner
layers of a multilayer flex circuit.
R2R is cost-effective because it eliminates the high potential
handling-damage risk of working with super-fine sheet substrates in manual or with automatic flex sheet handling mode,
resulting in higher quality and higher yields. It's estimated that
20 to 30% of flex circuits are produced with R2R processing today, and the majority are flex circuits targeted for smartphones.
Manufacturers that work with advanced designs see the great
benefits of moving to R2R direct imaging (DI) for two main
reasons. Firstly, the move from traditional exposure R2R to DI
R2R is estimated to improve yield by 10 to 15%, thus making DI
R2R an enabling process and critical to high-volume, high-yield
manufacturing. Secondly, the yield improvement gained from
moving from sheet-by-sheet manufacturing to R2R manufacturing is expected to be between 2 and 4 percent.

enabling the FPC to be scanned to ensure improved detection
with fewer false overcalls from the bottom pattern layers.
Until now, AOI has typically involved manually handling
panel sheets during the inspection and verification stages.
The manual method often results in handling damage for the
delicate and thin FPC sheets, creating a substantial increase
in scrap. Recently developed advanced AOI technologies
enable remote classification, which eliminates the need to
review the entire roll online or move up and down the roll to
find specific panels. This not only saves a great deal of time
as the verification process occurs simultaneously but also
ensures higher throughput and yield as it does away with
further manual handling with all its implications.
The various attributes of R2R help manufacturers increase
their precision and quality, while improving their production
throughput and yield and ultimately improving profits. Both
direct imaging and UV laser drilling, when used with R2R manufacturing equipment, reduce the handling and risk of damaging
the delicate flex PCBs.
Other recent advancements in R2R include increasing the
width of the flex materials it can process by up to 520 mm, a
welcome development for manufacturers and designers that
opens up a number of design improvements. So while direct
imaging with R2R is very fast, with a 260-mm roll printing at
20 mm/s X 260 mm, the output is approximately 19 m 2 per
hour. That output doubles with the wider 520 mm roll-in the
same timeframe.
And one of the more exciting developments in R2R manufacturing is the ability to change rolls more quickly on the manufacturing floor, streamlining the changeover and increasing
overall production.

Advancements in roll-to-roll

Conclusion

The R2R manufacturing market is quickly advancing, with new
capabilities for direct imaging, UV laser drilling, and automated
optical inspection (AOI). These advances dramatically boost
yields and make it more affordable for manufacturers to invest
in the R2R manufacturing process:
* Direct imaging-DI helps decrease overall cost of ownership while maintaining quality at high speeds. It provides
greater flexibility on a wide range of flex materials and
applications. Direct imaging, a staple in sheet-to-sheet flex
PCB manufacturing, is now available for R2R processing
and offers high depth-of-focus (DoF), enabling better defect
detection. In addition, DI enables the ability to image and
register, compensating for flex distortions.
* Flex laser drilling-Advanced UV laser drilling systems
can be employed to drill small vias through a wide range
of materials of varying thinness and strength, including
polyimide, LCP, coppers, and others, with limited or no
residue or damage to the bottom of the via, no undercut,
and with advanced registration accuracy.
* Flex AOI-With the transparency of polyimide-based material comes significant inspection challenges. New AOI tools
have been developed with triple-vision imaging capabilities,

Flexible printed circuits are invaluable for a wide range of applications, but producing these ultrathin, flexible, and fragile
interconnects comes with many challenges. Extra care must
be taken throughout the production process to ensure that the
technology benefits that these circuits enable aren't compromised by low yield rates and manufacturing inefficiencies that
ultimately drive up the cost of end devices.
Leveraging highly efficient R2R processing with advanced AOI,
direct imaging, and UV laser drilling capabilities is providing
designers with many more options for creating cutting-edge
electronics in the smallest form factors, and even in shapes yet
to be imagined.

The move to roll-to-roll manufacturing

Meny Gantz is the VP of marketing in Orbotech's Printed
Circuit Board (PCB) division, where he is responsible for
guiding the division's overall marketing and go-to-market
product strategies and product roadmaps. Meny joined
Orbotech in 2000 and has served in a number of product
management and marketing positions within the PCB division, both at
the company's HQ in Israel and in Asia Pacific. Meny is a graduate of
MIT's Artificial Intelligence: Implications for Business Strategy executive
program and has an executive MBA from Tel Aviv University.
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Evaluation Engineering

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