Photodefinable polymers containing perfluorocyclobutane groups

DETAILED DESCRIPTION OF THE INVENTION Polymers of the invention have at least one photoactive site, that is a grouping of atoms capable of absorbing energy from incident photonic radiation such that the polymer becomes less soluble or dispersible in at least one solvent or dispersing medium than it was before exposure to the incident photonic radiation.
Compounds of the invention also have such photoactive sites or photoactive precursors; in which case, a polymer made at least partially from such compounds containing photoactive sites becomes less soluble or dispersible upon photonic irradiation.
Decreasing solubility or dispersibility is also evidenced by differential solubility between exposed and unexposed polymer, for example in a layer, a first portion of which is exposed to incident photonic radiation and second portion of which remains unexposed.
The term "incident photonic radiation" or "actinic radiation" refers to energy in the form of electromagnetic waves of a wavelength capable of exciting bonding or non-bonding electrons in certain functional groups referred to herein as photoactive sites or the active portion of such sites to produce a chemical reaction.
The term polymer is used herein to include any compound or compounds comprised of two or more like or different monomer units.
Thus the term polymer includes prepolymers, dimers, trimers, tetramers and other oligomers.
Determining reduced solubility or dispersibility is within the skill in the art.
For instances a solid, gels or organic phase separates from a liquid medium; more solvent is required to dissolve or disperse the same weight of polymer; latex particles coalesce; an emulsion separates or requires additional stirring.
The polymer is optionally dissolved or dispersed in any medium effective therefor.
For instance, polymers of the invention are advantageously dissolved in solvents such as ethers, ketones, aromatic hydrocarbons, polar aprotic solvents, halocarbon solvents and the like.
Among these solvents, mesitylene, diglyme, n-methylpyrrolidinone, and dimethylformamide are advantageously used in electronic applications such as depositing a layer of polymer on a substrate such as a metal (e