Digital Signal Processing Reference
In-Depth Information
AmaTech
AmaTech coil winding principle
with interconnection
of coil wire ends with IC Module
Coil winding tool
Heat & Force
LF & HF wound coil
Inlet sheet
DF / 18.Nov.1996
Figure 12.5
Production of a semi-finished transponder by winding and placing the semi-
finished transponder on an inlet sheet (reproduced by permission of AmaTech GmbH & Co.
KG, Pfronten)
open points and onto the chosen material. The screen is raised and the print is complete.
All structures have a raster pattern due to the screen mesh. The elasticity of the screen
guarantees extremely high accuracy.
This procedure is used to print a coil of any shape directly onto an inlet foil
(Figure 12.8). So-called
polymer thick film pastes
(PTF) are used as the 'printing ink'.
These consist of the powder of a conductive material (silver, copper, graphite), a light
solvent, and a resin as the fixing agent. After drying out, a conductive film is left
behind in the printed shape on the inlet. The
surface resistance R
A
1
of the film is
1
around 5-100
/
and falls back to around 50-80% after lamination, since the
1
The surface resistance
R
A
of a quadratic conductive layer is dependent only upon the specific conductivity
κ
and the thickness
d
of the conductive layer and is quoted in
/
:
R
A
=
ρ
d
To determine the conductive track resistance, the surface resistance is multiplied by the ratio of length
l
to breadth
b
of the conductive track:
R
=
R
A
·
1
κ
·
d
=
l
b
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