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Click on images for details |
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Wavenumber Spiral FSAT: sensor fabrication PVDF is an ideal
substrate for the realization of FSATs suitable for sensing operation, due to
its flexibility, light weight and ease of processing. Several prototype
transducers have been fabricated, using various techniques. The most
convenient approach was found to be inkjet printing of the electrodes’
geometry on a metalized PVDF sheet using a polymeric ink that can act as a
mask for a subsequent etching step. The fabrication flow is described below. Step 1:
inkjet printing A black and white bitmap
representation of the electrodes’ pattern is produced and given as an input
to a Microfab Jetlab II
printing system. The polymeric ink is an ultraviolet (UV) curable optical
epoxy (Norland 89). The image is printed on one
side of an 110μm-thick
PVDF film featuring Copper/Nickel metallization on both sides. Fig. 1 shows a cross-sectional sketch of the process
step, while the printing progress can be viewed by playing Movie
1. |
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Fig.
1: Cross-sectional sketch of
process step 1. |
Movie
1: Printing in progress. |
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Step 2: UV curing After
printing is complete, the ink needs to be cured under UV light. An exposure
time of about 5 minutes was found to be adequate for this application. The
process step is illustrated in Fig. 2 and produces the result in Fig. 3. |
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Fig.
2: Cross-sectional sketch of
process step 2. |
Fig.
3: Sample after printing and UV
curing. |
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Step 3: metal
etching The obtained polymeric pattern provides sufficient coverage of underlying regions for wet etching of the metal, which is performed through a 15% solution of Ferric Chloride (FeCl3) in distilled water. The back side of the sample is protected to preserve its metallization, as illustrated in Fig. 4. After etching, the sample appears as shown in Fig. 5. |
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Fig.
4: Cross-sectional sketch of
process step 3. |
Fig.
5: Sample after metal etching. |
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Step 4: ink stripping Finally, the polymer ink
used as a mask for etching is stripped away with methylene
chloride and the sample is cleaned with methanol and isopropanol.
Details of this step are shown in Fig. 6 and Fig. 7. |
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Fig.
6: Cross-sectional sketch of
process step 4. |
Fig.
7: Sample after ink stripping. |
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Georgia
Institute of Technology – Contact Us: |
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Massimo Ruzzane Emanuele Baravelli Matteo
Senesi |
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