Evaluation Engineering - 20

INSPECTION

ON A ROLL: NEW MANUFACTURING
PROCESSES INSPIRED BY FLEX
Orbotech © 2020

By Meny Gantz
Flexible printed circuits (FPCs) are making a profound impact on electronic design, ushering in smaller, lighter, and
increasingly functional devices that would otherwise be difficult,
if not impossible, to build. Now, the market demand for highly
innovative circuits has roll-to-roll (R2R) manufacturing emerging as a truly effective means for printing FPCs in high volumes,
with minimum handling damage, with high yield, and at high
speeds.
The benefits of FPCs are enormous: they can be folded, bent,
bonded in place, or free-flexing in many different configurations
and in extremely high densities. Designers across a wide range
of applications from commercial printers, implantable medical
devices, and digital cameras to smart phones, automotive electronics, and beyond, embrace flex circuits for systems requiring reliable connectivity between moving parts, for designing
products with smaller form factors and light weight, and for
optimizing their packaging. As R2R manufacturing gains in
popularity and its capabilities are refined, the ability to improve
the yield of FPCs is a reality.

Industries driving innovation
For the last decade, smartphone development has been driving
flex circuit innovation to meet demands for ultrahigh functionality and connectivity speed in a light and thin design. FPCs,
with their lightweight, thin profile and ability to support fineline features, and flexibility to be bent and folded, are natural
must-have alternatives to replace bulky, rigid PCBs, connectors,
and cables.
Inside today's smartphones, there are often 20 or more strong,
thin flex circuits. These innovative FPCs range from relatively
simple circuits to sophisticated folded flex circuits, all within
exceptionally small enclosures. These FPCs may be simple,

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EVALUATION ENGINEERING FEBRUARY 2020

connecting the mainboard to the microphone or battery, or
more complex, enabling the delivery of huge data volumes of
high-resolution RGB multimedia from the processor to the color
OLED display, driving a 13-megapixel display.
Beyond smartphones, FPCs are rapidly finding their way into
automotive electronics. Inside smart and autonomous vehicles,
flex circuits are replacing the legacy cables connecting hundreds
of electronic devices spanning the car's computer, motor and
brake controls, radars, cameras, mobile antennas, internet connectivity, and widescreen dashboard display. Manufacturers
need connections that are lighter, less expensive to manufacture,
and more reliable, and FPCs are frequently the answer. FPC
manufacturers are even creating longer, thinner flex PCB highdensity flat cables-as long as two meters-to replace outdated
cables and connectors.

Keeping production capability ahead
of new device designs
With high demand from smartphone manufacturers and automakers, and the introduction of 5G, which will necessitate new
materials and better transmission, designers are pushing flex
circuits to their technological limits. Simultaneously, innovative
new designs are pressuring flex circuit suppliers to accelerate
production processes and lower costs.
Demands for even higher density capabilities in flex circuits
require thinner layers and finer conductive lines. The inherent
physical fragility of flex circuits-thin materials are prone to
wrinkling and stretching-pose some key manufacturing challenges that can negatively affect yield and potentially impact
a design's viability.
These challenges are being addressed by flex-supporting
technologies that enable large-scale flex PCB production while
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