Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
2002-01-22
2004-01-27
Huff, Mark F. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S270100, C430S905000, C430S913000, C428S424700, C428S424800, C428S522000
Reexamination Certificate
active
06682872
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to radiation-curable compositions based on a mixture of organic constituents or organic-inorganic hybrid systems for use in the fabrication of electronic components, and, in particular, as multi-purpose coatings, such as passivation coatings; for defect repair in ceramic and thin film products by micropassivation in high circuit density electronic modules to allow product recovery; as a solder mask in electronic assembly processes; for use as protective coatings on printed circuit board (PCB) circuitry and electronic devices against mechanical damage and corrosion from exposure to the environment.
2. Description of Related Art
A number of uv-curable compositions for use as protective coatings and PCB solder mask applications in low temperature soldering processes for component attachment have been described in the literature and many of such uv-curable materials are commercially available. In the solder mask application, for example, the solder mask composition covers the selected areas of the printed wiring board (PWB) circuitry allowing selective soldering of the areas which are not covered by the mask and prevents solder bridges. The solder mask is typically kept permanently in place to provide long term insulation and protection against mechanical and environmental damage.
U.S. Pat. No. 4,533,445 (Orio et. al.) describes a uv-curable solder mask composition with good adhesion to copper and Pb—Sn solder, comprising an epoxy resin, an acrylated monomer/oligomer, a photoinitiator, and an inorganic filler. These compositions are screen printed onto circuit boards.
U.S. Pat. No. 4,544,623 (Audykowski et al.) discloses photosensitive coating compositions and use thereof for protective purposes such as a solder mask on a PWB. These compositions contain organic solvents and are based on a photosensitive epoxide resin carrying an ethylenically unsaturated group bound as a side chain or a molecular chain as chalcone group, a customary curing agent, a cure accelerator and an organic or inorganic filler.
U.S. Pat. No. 4,614,704 (Hung et.al.) describes a uv-curable composition comprising triphenyl phosphite for forming solder mask coatings of high cure depth.
The uv-curable compositions described in the art are generally based on epoxide resin, epoxide/acrylic resins or epoxide/acrylated urethanes, which also carry organic solvents in some cases. The problem with epoxy based crosslinked thermoset materials as protective coatings on organic, inorganic, and metal surfaces is that these are high stress, high modulus and generally brittle materials which also have the problem of high moisture uptake. The presence of organic solvents in uv-curable formulations also has several problems, for example, solvent outgassing during cure, flammability, chemical safety, and health hazard when using low boiling solvents. In addition, some of the solvents are classified as VOC (Volatile Organic Compounds) or HAPs (Hazardous Air Pollutants), which are subject to environmental regulations requiring strict control of volatile emissions using special emission control devices and which in some cases require record keeping and regular reporting of emissions.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide solvent-less, radiation-curable, particularly uv-curable, compositions, which contain all organic components and, which compositions are for use in the fabrication of electronic components such as for use as passivation coatings on electronic components, for micropassivation to repair defects and carry out engineering changes in assembled high circuit density electronic modules, and thereby allowing product recovery and cost reduction by preventing yield loss.
It is another object of the present invention to provide solvent-free, radiation-curable, particularly uv-curable, organic-inorganic hybrid compositions to form filler-reinforced polymer composites for use in the fabrication of electronic components such as for defect repair and carry out engineering changes in ceramic and thin film structures of assembled high cost high circuit density electronic modules to provide recovery of finished product which otherwise would be discarded adding to the overall product cost and increasing the product waste.
Another object of this invention is to provide a method of use of these compositions in the fabrication of electronic components such as passivation and protective coatings on PWB circuitry and for protection of electronic devices against mechanical damage and corrosion from exposure to the environment.
Yet another object of this invention is to provide solvent-free, radiation-curable, particularly uv-curable, nanocomposite compositions, using organically modified inorganic nano-fillers in a uv-curable organic binder system and use of these nanocomposite compositions in the fabrication of electronic components such as for micropassivation and to repair defects or imperfections in ceramic and thin film products in high circuit density ceramic modules to provide waste reduction and cost reduction by product recovery and recycle.
A further object of the present invention is to provide solvent-free, radiation-curable, particularly uv-curable, polymer-filler composite compositions using conventional inorganic and/or organic fillers, polymer-nanofiller nanocomposites and use thereof in microelectronics fabrication, such as, solder mask in electronic component assembly processes; uv-curable passivation and protective coatings for device protection against mechanical damage and detrimental effects of environmental exposure, and for defect repair in assembled high circuit density electronic modules.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
SUMMARY OF THE INVENTION
The above and other objects and advantages, which will be apparent to one of skill in the art, are achieved in the present invention which is directed to, in a first aspect, solvent-free, radiation-curable, preferably uv-curable, compositions formed by blending a polymer binder, which is a pre-formed thermoplastic or elastomeric polymer/oligomer, a monofunctional and/or bifunctional acrylic monomer, a multifunctional (more than 2 reactive groups) acrylated/methacrylated monomer, and a photoinitiator, where all the constituents are mutually miscible forming a homogeneous viscous blend without the addition of an organic solvent.
In another aspect of the invention radiation-curable, preferably uv-curable organic-inorganic hybrid compositions, are provided that are formed by dispersing an inorganic filler in the above compositions to provide polymer-filler composite compositions and nanocomposite compositions depending on the type of filler used.
These compositions may also contain other additives, for example, surfactants, coloring agents, adhesion promoters, antioxidants, and corrosion inhibitors.
In a further aspect, these compositions are applied on the desired area by standard methods of syringe dispensing, spraying, roller coating, or screen printing, and subjected to curing by exposure to uv according to conventional methods, which can optionally be followed by a thermal cure for crosslinking any residual reactive species, e.g., monomeric and/or oligomeric species.
In a further aspect of the invention, a method is provided for repairing defects in high circuit density electronic modules for product recovery so as to provide product cost reduction by preventing yield loss and reduce waste. For thin film repair in advanced high circuit density ceramic modules, the uv curable composition is selectively dispensed on the defect site of the electronic module, cured by exposure to uv-radiation, subjected to laser ablation to expose the embedded defect region through the uv cured material, and repairing the underlying defect by making engineering changes for product recovery.
In another aspect of the invention, t
Berger Michael
Gorrell Rebecca Y.
Monjeau Gregg B.
Perry Bernadette H.
Sachdev Krishna G.
Chacko-Davis Daborah
Cioffi James J.
DeLio & Peterson LLC
Huff Mark F.
International Business Machines - Corporation
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