Chemistry Reference
In-Depth Information
Table 3.
Dielectric constant anisotropy data for 50/50 6FPBO-OH-co-12FPBO polymer
Waveguide results
λ (nm)
n
x, y
n
z
∆n
ε
x, y
ε
z
∆ε
632.8
1.5965
1.5523
0.044
2.549
2.410
0.139
1152
1.5613
1.5230
0.038
2.438
2.320
0.118
Electrical measurements
(10
5
Hz) ε
z
= 2.19
Transverse dielectric constant
∆ε = 0.14
(10
5
Hz) ε
x, y
= 2.33
Longitudinal dielectric constant
was also investigated by
comparing the dielectric constant from transverse impedance measurements with
that from interdigitated electrode measurements. The results at 10
5
Hz are also
listed in Table 3, this frequency being the upper frequency limit of the interdigi-
tated electrode method. It is seen that the anisotropy from the electrical method is
0.14, which is consistent with the optical anisotropy values. These values are
within acceptable standards for integrated circuit packaging [3, 15, 16].
A number of polymers and copolymers with very low, practical dielectric con-
stants have been synthesized and characterized. A likely candidate for the high
temperature processing of high-speed integrated circuits would be polymer
The anisotropy of the dielectric constant of polymer
6
6
,
50/50 6FPBO-OH-co-12FPBO. The T
g
is 362
°
C, T
d
is 532
°
C, moisture uptake is
<
0.2% and the coefficient of thermal expansion is 53 ppm from -127
°
C to
323
C. The dielectric constant is 2.15 at 1 MHz, low enough to be considered
suitable for microelectronic devices. The dielectric anisotropy of 0.14 is also
within acceptable limits for such an application. If a higher T
g
is required, the
candidate would be the homopolymer
°
3
with a T
g
of 426
°
C, but with a somewhat
higher dielectric constant at 1 MHz of 2.35.
3.4. Post-polymer reactions via O-allylation of monohydroxy-6F-benzoxazole
polymers
Aromatic benzoxazole homo- and copolymers containing allyl ether pendent
groups were synthesized in quantitative yields and with high molecular weights as
evidenced by their intrinsic viscosities (Table 4) and the tenacity of the films fab-
ricated from chloroform or THF. The allylation of the hydroxyl pendants in the
polymers was generally very extensive as indicated by IR spectra and elemental
analysis. Corroboratively, it was found that model O-allylated compounds in this
study were pure materials obtained in moderate to good yields, characterized by
sharp melting points, mass spectra, and elemental analysis.
The proof of the concept for achieving enhancement of the T
g
of O-allylated
6F-benzoxazole polymers via Claisen rearrangement and imparting solvent resis-
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