Synthesis and characterization of photosensitive benzocyclobutene‐functionalized siloxane thermosets

Abstract

Two methylphenylsiloxane monomers with crosslinkable benzocyclobutene functionalities at the terminal positions, 1,1,5,5‐dimethyldiphenyl‐1,1,5,5‐di[2′‐(4′‐benzocyclobutenyl)vinyl]‐3,3‐diphenyltrisiloxane (BCB‐1) and 1,1,3,3‐dimethyl‐diphenyl‐1,1,3,3‐di[2′‐(4′‐benzocyclobutenyl)vinyl]disiloxane (BCB‐2) were prepared and characterized. By heating the solution of BCB‐1 and BCB‐2 in mesitylene, two partially polymerized resins of BCB‐1B and BCB‐2B with high molecular weight were also achieved. The monomers and their oligomers fully cured at temperatures above 250 °C. Cured BCB‐1 and BCB‐2 exhibited high Tg (257 and 383 °C) and good thermal stability (T5% > 472 °C both in N2 and in air). They also demonstrated low dielectric constants (2.69 and 2.66), low dissipation factors (2.36 and 2.23), and low water absorptions (0.20% and 0.17%). Moreover, a negative photosensitive formulation derived from BCB‐1B in combination with 2,6‐bis(4‐azidobenzylidene)‐4‐methylcyclohexanone (BAC‐M) as a photosensitive agent has been developed. The photosensitive composition, BCB‐1B containing 5 wt % BAC‐M, showed a sensitivity of 550 mJ/cm2 and a contrast of 1.96 when it was exposed to a 365 nm light (i‐line) and developed with cyclohexanone at 25 °C. A fine negative image of 10 μm line‐and‐space pattern was also printed in a film which was exposed to 700 mJ/cm2 of i‐line by contact‐printing mode. The negative image can be maintained without any pattern deformation in the curing process. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6246–6258, 2009

Adamantyl-based benzocyclobutene low-k polymers with good physical properties and excellent planarity

“…27,28 Then the oligomer was spin-coated on the silicon wafer and heated at 250 1C for about 4 hours under vacuum. 27,28 Then the oligomer was spin-coated on the silicon wafer and heated at 250 1C for about 4 hours under vacuum.…”

Synthesis and properties of novel benzocyclobutene-functionalized siloxane thermosets

“…), the characteristic absorptions of the two monomers appeared at the same location because of their similar chemical structures. The characteristic absorption bands were assigned as follows (BCB‐(SiO) 1 ): 1771 and 1708 cm –1 , the asymmetric and symmetric stretching vibration of C = O of the imide structure; 1375 cm –1 , the stretching vibration of the C–N bond; 1062 cm –1 , the stretching vibration of Si–O–Si; 1474 cm –1 , the in‐plane vibration of C–H in the strained four‐membered ring on the BCB group . The 1 H NMR spectra of BCB‐(SiO) 1 and BCB‐(SiO) 7 are shown in Fig.…”

“…Generally, BCB‐based monomers are synthesized from 4‐aminoBCB, 4‐carboxylBCB or 4‐bromoBCB . Among them, bis/multi‐BCB‐functionalized monomers are receiving increased attention for their excellent mechanical properties and high glass transition temperature ( T g ) after cure .…”

“…it uses an expensive noble metal (palladium) as catalyst and toxic triphenylphosphine as ligand. In addition, purification of the product is tedious . Tan et al .…”

Directly patternable benzocyclobutene and methacrylate silsesquioxanes for microelectronics packaging

“…The Dow product, Cyclotene is a hybrid organicinorganic dielectric material that has been reported to have a dielectric constant of 2.65, a CTE ranging from 42 to 55 ppm/K 14) and there are some reports of direct patternability of Cyclotene down to 10¯m half pitch. 15),16) While these specifications do not quite meet the requirements for today's modern packaging standards, Cyclotene is an excellent example of the utility of BCB based thermosets. We have created two new photopatternable, BCB and POSS based resins which may be of interest to a variety of polymer and materials based applications, however we have evaluated their properties for a potential application in microelectronics packaging.…”