Verifying a mould’s dimensions
for a RF tag printed by inkjet

When using functional inks withinkjet technologies to create
microelectronic devices, there’s
a need to verify any differences
between the desired design
and what’s actually printed; theheight and shape of the printed
layers is integral to optimal device
configuration and functionality.

The Barcelona Microelectronics
Institute (IMB) is the National
Microelectronics Centre (CNM)’s
Barcelona location and amember of the Spanish ResearchCouncil. IMB-CNM focuses onbasic and applied research anddevelopment, in addition toeducation and training in micro andnanotechnologies, components
and systems. Our mission is toexpand the knowledge available
in this field and to contribute to
the implementation of solutions
and new products based in thesetechnologies in order to resolve thechallenges faced by society today.
Project currently being undertaken
by Mr. Roger Escudé.

Figure [1] Antenna mould.

CASE STUDY VERIFYING A MOULD’S DIMENSIONS FOR A RF TAG PRINTED BY INKJET

1

■ Measurements
The antenna’s mould has 4 tracks that create 5 valleys that are filled withsilver ink. Each mould track is 600 µm wide and 15 µm high.

Figure [2]Detailof theantenna
mouldfilled silver
ink to build
up theantenna.

Figure [3]Detail of themould andantenna
tracks.

The device’s purpose is measuring e-coli bacteria on a hand-paper dispenser
where the tag is printed on the paper. The antenna is connected to aninterdigitated capacitor that behaves like a bacterial sensor, when there arechanges the capacitor’s value affects the antenna resonance’s frequency;
these variables are easy to measure with a RF transceiver.
Currently, these kinds of devices tend to use contact profilometers thatprovide measures that aren’t as precise as we need them to be.
With Sensofar’s 3D optical profiler we are able to check the mould heightand calculate if there will be a sufficient layer of silver bulk to achieve thedesired conductivity for good performance.

2CASE STUDY VERIFYING A MOULD’S DIMENSIONS FOR A RF TAG PRINTED BY INKJET

Figure [4] (a) 3D topoghraphy of the antenna’s mould printed on PEN substrate.
(b) Profile of the antenna’s mould.

■ Conclusions
By verifying with a Sensofar Plμ neox using the confocal technique with a20X brightfield objective that the RF antenna’s shape was as desired andpossessed an adequate silver layer, good conductivity was ensured.
The Sensofar equipment provided non-contact 3D surface profilers based on
three technologies: Confocal, Interferometry and Focus Variation techniques
and allowed us to obtain high-resolution measurements in a fast and nondestructive way, with user-friendly software for technical support.

Figure [6] 3D topography

showing mould trackdetail.

CASE STUDY VERIFYING A MOULD’S DIMENSIONS FOR A RF TAG PRINTED BY INKJET

3SENSOFAR is a leading-edge technology
company that has the highest quality standards
within the field of surface metrology
Sensofar Metrology provides high-accuracy optical profilers
based on confocal, interferometry and focus variation
techniques, from standard setups for R&D and quality
inspection laboratories to complete non-contact metrology
solutions for in-line production processes. The Sensofar Grouphas its headquarters in Barcelona, also known as a technology
and innovation hub in Europe. The Group is represented in over
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