Polyimides (PI's) with low-dielectric constant and excellent organic solubility have broad application prospects in the electronic field. Herein, this study designed a series of novel, low dielectric, organic soluble PI films by creatively introducing fluorene and pyridine ring into diamine monomers. Because of the noncoplanar structure of fluorenyl and the polarization of pyridine ring, PI films achieved a low-dielectric constant (2.22–3.09 at 10 MHz) and excellent organic solubility. Even in some organic solvents with low-boiling points, these PI films still exhibited outstanding solubility. In addition, all the films possessed high-tensile strength (≈120 MPa) and excellent optical transparency (>70%, 450 nm). It was worth noting that the glass transition temperature of films was all above 280°C and 5% weight loss temperature ( T 5% ) was at 486–553°C. In general, the novel high-performance low-dielectric PI films are expected to be used in the field of microelectronics. Graphical A series of novel, low dielectric, organic soluble PI films are synthesized by creatively introducing fluorene and pyridine ring into diamine monomers. Compared with traditional Kapton film, these new polyimides containing fluorenyl and pyridine heterocycles in the main chain have low-dielectric constants.
Benzocyclobutene resins play an important role in microelectronic industry owing to their excellent physical and chemical properties. In our work, three novel benzocyclobutene-terminated imide monomers were synthesized via the reaction of 1-aminomethyl benzocyclobutene with various aromatic dianhydrides. The monomers exhibited good processability with superior solubility and low melting points (<163.5 °C), and they showed similar curing behaviors under N 2 with an exothermic peak in differential scanning calorimetry (DSC) curves ranging from 217.3 °C to 287.7 °C. Highly crosslinked resins obtained at 150–300 °C exhibited superior tensile strength (>74.3 MPa), outstanding thermal stability (T d > 466 °C in N 2 ), high glass transition temperature (>278 °C), high storage modulus (>3.25 GPa at 30 °C), low dielectric constant (<3.07 at 1 MHz) and good water resistance (the water absorption was below 0.81% after immersed in water for 24 h and the water contact angle was higher than 86.6°). Atomic force microscopy demonstrated the perfect uniformity and planarity of the cured films.
Two different aromatic diamines monomers (3, 5-diamino-N-(4'-phenyl-4''-triphenylamino)-N-(4''-benzyl-4'''-triphenylamino)benzamide (DPTBTB) and 3, 5-diamino-N-(4'-3'', 4'', 5''-trifluorobiphenyl)-N-(4''-benzyl-3''', 4''', 5'''-trifluorophenyl)benzamide (DTBTB)) containing flexible linkages were designed and synthesized, respectively. Four organo-solubility polyimides (PI-a, PI-b, PI-c, and PI-d) were prepared via a two-step procedure with pyromellitic dianhydride (PMDA) and 3, 3', 4, 4'-biphenyltetracarboxylic dianhydride (BPDA), respectively. The four PIs performed excellent thermal stability with the temperature of 5% weight loss in range of 370–420 ℃ at N 2 atmosphere. The Al/PI-a/ITO and Al/PI-b/ITO memory devices exhibited binary write-once-many-read (WORM) and rewritable (Flash) behavior, respectively. But the Al/PI-c/ITO and Al/PI-d/ITO memory devices showed ternary WORM and Flash behavior due to the deeper charge traps came from the fluorinated groups in the structure of PI-c and PI-d, respectively. The memory switching mechanism could be demonstrated through molecular simulation. The results gave an effective strategy that adjusting the structure of PI to achieve different memory effects.
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