Fengkai He

A novel one-pot synthesized organosiloxane: synthesis and conversion to directly thermo-crosslinked polysiloxanes with low dielectric constants and excellent thermostability

A novel organosiloxane containing a thermally cross-linkable benzocyclobutene group was successfully synthesized through a one-pot Grignard reaction procedure. The organosiloxane can be easily polymerized or copolymerized to form the oligomers which can be directly converted to cross-linked network structures with excellent thermostability and low dielectric constants, implying that the organosiloxane has potential application in the electrical and microelectronics industry.

Postpolymerization of a Fluorinated and Reactive Poly(aryl ether): An Efficient Way To Balance the Solubility and Solvent Resistance of the Polymer

A new fluorinated poly(aryl ether) with reactive benzocyclobutene groups as the side chain was successfully synthesized. This polymer showed a number-average molecular weight (Mn) of 200,000 and had good solubility and film-forming ability. After being postpolymerized at high temperature (>200 °C), the polymer film converted to a cross-linked network structure, which was insoluble in the common organic solvents. Such results suggest that the postpolymerization is an efficient way to achive the balance between the solubility and the solvent resistance of the polymer. TGA data showed that the postpolymerized polymer had a 5 wt % loss temperature at 495 °C and a residual of 61% at 1000 °C under N2. The cross-linked film also exhibited good dielectric properties with an average dielectric constant of about 2.62 in a range of frequencies from 1 to 30 MHz. With regard to the mechanical properties, the cross-linked film had hardness, Youngs modulus, and bonding strength to a silicon wafer of 1.22, 8.8, and 0.89 GPa, respectively. These data imply that this new polymer may have potential applications in the electrical and microelectronics industry.

Benzocyclobutene resin with fluorene backbone: a novel thermosetting material with high thermostability and low dielectric constant

A fluorene-based monomer (FB) with thermally cross-linkable benzocyclobutene groups is reported here. This monomer showed good solubility in the common organic solvents and had a low melting point (128 °C). When being treated at high temperature (>200 °C), the monomer was converted to a cross-linked network structure (PFB). TGA data exhibited that PFB had high thermostability with a 5% weight loss temperature of 437 °C and 372 °C in N2 and air, respectively. Moreover, PFB showed a char yield of 47.6% at 1000 °C in N2. With regard to the electrical properties, PFB indicated an average of dielectric constants of about 2.7 ranging from 0.15 MHz to 30 MHz. All these results suggest that FB could be used as the varnish for insulating enameled wire in the electrical industry, and as encapsulation resins in the microelectronics industry.

A new low dielectric material with high thermostability based on a thermosetting trifluoromethyl substituted aromatic molecule

A thermally cross-linkable molecule composed of bis(trifluoromethyl)benzene and benzocyclobutene units (F1) was successfully prepared. Heating F1 (>200 °C) gave a cured resin, which showed a dielectric constant (k) of 2.47 at 30 MHz and an average k value of less than 2.51 in a range of frequencies from 0.15 MHz to 30 MHz. Such low k values are comparable to other polymeric low-k materials. For comparison, a perfluorobenzene with benzocyclobutene groups (F2) was also synthesized. The cured F2 exhibited an average k value of 2.98, indicating that the introduction of a trifluoromethyl group into the backbone of the molecules can efficiently decrease the dielectric constant of the molecules. The cured F1 also exhibited high thermostability (T5 = 429 °C, weight residual = 47.7% at 1000 °C under N2). These results suggest that F1 is suitable for the utilization in ultra large scale integration circuits.

A new polymer with low dielectric constant based on trifluoromethyl-substituted arene: preparation and properties

A new polymer with low dielectric constant is reported here. This polymer contains a trifluoromethyl-substituted phenyl unit and a binaphthyl unit, and shows high thermostability with a glass transition temperature of 244 degrees C and a 5 wt% loss at temperature 518 degrees C under nitrogen. The polymer also exhibits good film-forming ability, and the formed films exhibit high hydrophobicity with a contact angle of 103.6 degrees with water. In a range of frequencies from 1 to 25 MHz, the polymer reveals an average dielectric constants of about 2.56. In regard to the mechanical properties, the polymer film shows an average hardness of 0.37 GPa and a Youngs modulus of 15.07 GPa. These results indicate that the polymer could be used as a varnish for enameled wire, sizing agents for high-performance carbon fiber, and the matrix resin for the production of laminated composites utilized in the printed-circuit-board (PCB) industry.

Facile conversion of plant oil (anethole) to a high-performance material

Anethole, a naturally occurring aromatic compound which can be extracted abundantly from plants like star anise, fennel and basil, has been conveniently transformed to a functional monomer in an overall yield of 81% via a two-step procedure. The obtained monomer combines reactive benzocyclobutene and propylene groups, thus it can undergo thermo-polymerization to form a crosslinking network, showing a low dielectric constant (<2.64 in a range of frequencies varying from 0.1 to 30 MHz) and low water uptake (<0.20% in boiling water for 144 h). TGA and DSC data exhibit that the cross-linked network has a 5 wt% loss temperature of 455 °C in N2 and a Tg of 160 °C, respectively. These results indicate that the new polymer based on biorenewable anethole is comparable to the materials derived from petroleum. On the basis of the wide application of low dielectric constant materials in the microelectronic industry, this work would offer a new sustainable feedstock to organic low k materials. Moreover, this contribution also provides a new route to convert other aromatic natural products.