Newspapers and magazines are closing left and right, but
one form of printing is ready to take off.
It's the large-scale print-manufacturing of complex 3-D
structures using a new additive manufacturing technology called High-Volume
Print Forming invented by the scion of a Boston newspaper family.
Charles
S. Taylor, the grandson of Boston Globe publisher Charles H.
Taylor, developed manufacturing technology in which converted commercial
printing equipment produces tiny layers of materials that stack up to produce
complex designs with multiple functions.
That technology is now in the final qualification stage
for antennas used in cell phones and is on the verge of becoming a major player
in IC packages for portable electronics. Other potential applications include fluidic
parts, energy harvesters, fuel cell parts and sensors.
"The sweet spot for the technology is parts that are about
the size of paper clips," says Arthur L. Chait, president and CEO of EoPlex,
the company started by Taylor in 2001. "One thing that really differentiates
this technology from rapid prototyping is the ability to use many materials."
The process can use as many as six materials at a time,
and the range of those materials is almost limitless - another huge difference
from rapid prototyping.
The materials catalog for High-Volume Print Forming includes:
- Glass-ceramic composites;
- Piezoelectric materials (PZT);
- Oxides such as alumina (Al2O3), silica (SiO2), and zirconia (Zr2O3);
- Custom low-loss dielectrics;
- Structural metals such as nickel alloys, stainless steel, iron;
- Conductors such as palladium, silver, gold, platinum; and
- A wide variety of plastics with and without fillers.
Chait says plastics can have three different roles in the process: as a binder that permits flow, a structural material and/or as a sacrificial material.
The process starts with the development of "pastes" or "inks" that are highly loaded with materials such as metals or ceramics. These formulations are developed by chemists at EoPlex and are highly proprietary.
Photo Tooling
The printer works with a support system as a printing
platen to reassemble a CAD-created structure that has been horizontally sliced
into many thin layers. Files from any commercial 3-D CAD system are used to
create photo tooling and printing masks. Printing masks and photo tooling are
usually available in about two weeks.
The printing portion of the process is similar to
"two-dimensional" systems such as screen printing, flexo, gravure or
offset lithography. A screen-printer machine pushes material with a
squeegee-like device through a fine screen with a pattern of open spaces to
create a pattern. The screen functions as a stencil. A sacrificial material is
printed to form a temporary support around the positive ink. Many sheets are stacked
up like pages in a book and part of the magic is that each layer must cure
quickly to allow the next layer to begin.
Chait says the company is printing many tiny objects on a
given sheet so the process is suitable for mass production. Further processing
may involve sintering in an oven, much as in powder injection molding. "The
shrinkage may be as much as 15 or 20 percent," he says.
Charles Taylor originally invented the process as a way
to make superior medical devices, such as stents. But the technology is getting
significant traction for electronics components, such as cell phone antennas or
IC packages.
Cell Phone Takeoff
"Early antenna designs were easily manufactured by
conventional ceramic techniques," says Chait. But growth in cell phone
applications created demand for more complex, small antennas.
Existing manufacturing processes, such as green tape LTCC,
have limitations, such as materials inflexibility and three-dimensional design
constraints. With the EoPlex process, says Chait, "(design
engineers) get high efficiencies, wide bandwidths, low costs and small sizes."
Chait says EoPlex plans to co-locate factories with major
customers' manufacturing plants.
"This is a solution that OEMs have been waiting for," he
says. "And to top it off, it's green."
