Abstract: A method for densifying thermoplastics, particularly polyimides, for use in conjunction with electronic circuits while producing improved physical properties and a high degree of crystallinity, involves variable frequency microwave (VFM) processing at temperatures typically 100° C. below the glass transition temperature or lower, for times of about 50 to 100 minutes. It is particularly applicable to polymers based on BPDA-PPD, but may also be generally applied to other intentionally designed polyimide structures with the same features. The invention enables the creation of layered structures involving integrated circuits with small feature sizes and overcoatings of polymers with high Tg and other desirable properties.

Abstract: A multilayer structure comprises: a substrate; and, a plurality of polymerizable layers successively deposited on the substrate, with each successive layer having a greater dielectric polarizability than the preceding layer(s), so that each successive layer will absorb microwave energy preferentially to the preceding layer(s). In this way, successive layers can be cured without over-curing the preceding layers. The individual layers are preferably materials from a single chemical family (e.g., epoxies, polyimides, PBO, etc.) and have similar properties after curing. The dielectric polarizabilities may be adjusted by modifying such factors as chain endcap dipole strength, cross-linker dipole strength, promoter, solvent, and backbone type. The invention is particularly suitable for producing various polymer layers on silicon for electronic applications. An associated method is also disclosed.

Abstract: A method for densifying thermoplastics, particularly polyimides, for use in conjunction with electronic circuits while producing improved physical properties and a high degree of crystallinity, involves variable frequency microwave (VFM) processing at temperatures typically 100° C. below the glass transition temperature or lower, for times of about 50 to 100 minutes. It is particularly applicable to polymers based on BPDA-PPD, but may also be generally applied to other intentionally designed polyimide structures with the same features. The invention enables the creation of layered structures involving integrated circuits with small feature sizes and overcoatings of polymers with high Tg and other desirable properties.

Abstract: A method for densifying thermoplastics, particularly polyimides, for use in conjunction with electronic circuits while producing improved physical properties and a high degree of crystallinity, involves variable frequency microwave (VFM) processing at temperatures typically 100° C. below the glass transition temperature or lower, for times of about 50 to 100 minutes. It is particularly applicable to polymers based on BPDA-PPD, but may also be generally applied to other intentionally designed polyimide structures with the same features. The invention enables the creation of layered structures involving integrated circuits with small feature sizes and overcoatings of polymers with high Tg and other desirable properties.

Abstract: A method for curing photosensitive polyimide (PSPI) films includes the steps of: depositing a PSPI film on a selected substrate, and curing the film by microwave heating at a selected temperature from about 200 to 340° C. in a selected atmosphere containing an oxygen concentration from about 20 to 200,000 ppm. The process atmosphere may be static or flowing. The addition of oxygen improves the removal of acrylate residue and improves the Tg of the cured film, while the low processing temperature characteristic of the microwave process prevents the oxygen from damaging the polyimide backbone. The method may further include the steps of photopatterning and developing the PSPI film prior to curing. The process is particularly suitable for dielectric films on silicon for electronic applications.

Abstract: A method for curing photosensitive polyimide (PSPI) films includes the steps of: depositing a PSPI film on a selected substrate, and curing the film by microwave heating at a selected temperature from about 200 to 340° C. in a selected atmosphere containing an oxygen concentration from about 20 to 200,000 ppm. The process atmosphere may be static or flowing. The addition of oxygen improves the removal of acrylate residue and improves the Tg of the cured film, while the low processing temperature characteristic of the microwave process prevents the oxygen from damaging the polyimide backbone. The method may further include the steps of photopatterning and developing the PSPI film prior to curing. The process is particularly suitable for dielectric films on silicon for electronic applications.

Abstract: A method for curing photosensitive polyimide (PSPI) films includes the steps of: depositing a PSPI film on a selected substrate, and curing the film by microwave heating at a selected temperature from about 200 to 340° C. in a selected atmosphere containing an oxygen concentration from about 20 to 200,000 ppm. The process atmosphere may be static or flowing. The addition of oxygen improves the removal of acrylate residue and improves the Tg of the cured film, while the low processing temperature characteristic of the microwave process prevents the oxygen from damaging the polyimide backbone. The method may further include the steps of photopatterning and developing the PSPI film prior to curing. The process is particularly suitable for dielectric films on silicon for electronic applications.

Abstract: A method for forming a multilayer structure comprises the steps of: depositing a first polymerizable layer on a substrate; applying microwave energy to the polymerizable layer while monitoring at least one property of the layer; and, ending the application of microwave energy when the monitored property indicates that the polymerizable layer has reached a desired degree of cure. The property monitored may be optical, e.g., Raman spectrum, or electrical, e.g., dielectric loss. This process control strategy lowers the overall thermal budget, and is especially suitable for curing polymer films on silicon. The method may be used repetitively to cure multiple layers of polymeric material when a thicker film is needed.

Abstract: A method for curing photosensitive polyimide (PSPI) films includes the steps of: depositing a PSPI film on a selected substrate, and curing the film by microwave heating at a selected temperature from about 200 to 340° C. in a selected atmosphere containing an oxygen concentration from about 20 to 200,000 ppm. The process atmosphere may be static or flowing. The addition of oxygen improves the removal of acrylate residue and improves the Tg of the cured film, while the low processing temperature characteristic of the microwave process prevents the oxygen from damaging the polyimide backbone. The method may further include the steps of photopatterning and developing the PSPI film prior to curing. The process is particularly suitable for dielectric films on silicon for electronic applications.

Abstract: A method for densifying thermoplastics, particularly polyimides, for use in conjunction with electronic circuits while producing improved physical properties and a high degree of crystallinity, involves variable frequency microwave (VFM) processing at temperatures typically 100° C. below the glass transition temperature or lower, for times of about 50 to 100 minutes. It is particularly applicable to polymers based on BPDA-PPD, but may also be generally applied to other intentionally designed polyimide structures with the same features. The invention enables the creation of layered structures involving integrated circuits with small feature sizes and overcoatings of polymers with high Tg and other desirable properties.

Abstract: A multilayer structure comprises: a substrate; and, a plurality of polymerizable layers successively deposited on the substrate, with each successive layer having a greater dielectric polarizability than the preceding layer(s), so that each successive layer will absorb microwave energy preferentially to the preceding layer(s). In this way, successive layers can be cured without over-curing the preceding layers. The individual layers are preferably materials from a single chemical family (e.g., epoxies, polyimides, PBO, etc.) and have similar properties after curing. The dielectric polarizabilities may be adjusted by modifying such factors as chain endcap dipole strength, cross-linker dipole strength, promoter, solvent, and backbone type. The invention is particularly suitable for producing various polymer layers on silicon for electronic applications. An associated method is also disclosed.

Abstract: A stacked die package is formed by stiffening a flexible substrate, arranging a chip mounting pattern on one side of the substrate, and mounting chips according to the arranged pattern. A solder ball array on the opposite side of the substrate is routed to the chips, and the flexible substrate and stiffener are folded to align the chips in the stacked die package. The stiffener is removed by a single saw cut.

Abstract: A method for forming a high voltage component package, which includes providing a flexible non-conductive substrate, forming a conductive layer on the substrate, and forming a circuit trace from the conductive layer, the circuit trace having frangible leads. A first side of a component overlies at least a portion of the circuit trace, and the component is coupled to the circuit trace by breaking a frangible lead on the trace and bonding the lead to the component. The flexible substrate is then bent or folded such that another portion of the circuit trace is in proximity to a second side of the component. The trace is coupled to the second side of the component either with a conductive adhesive or by bonding with another frangible trace.

Abstract: A method for forming a high voltage component package, which includes providing a flexible non-conductive substrate, forming a conductive layer on the substrate, and forming a circuit trace from the conductive layer, the circuit trace having frangible leads. A first side of a component overlies at least a portion of the circuit trace, and the component is coupled to the circuit trace by breaking a frangible lead on the trace and bonding the lead to the component. The flexible substrate is then bent or folded such that another portion of the circuit trace is in proximity to a second side of the component. The trace is coupled to the second side of the component either with a conductive adhesive or by bonding with another frangible trace.

Abstract: A stacked die package is formed by stiffening a flexible substrate, arranging a chip mounting pattern on one side of the substrate, and mounting chips according to the arranged pattern. A solder ball array on the opposite side of the substrate is routed to the chips, and the flexible substrate and stiffener are folded to align the chips in the stacked die package. The stiffener is removed by a single saw cut.

Abstract: A stacked die package is formed by stiffening a flexible substrate, arranging a chip mounting pattern on one side of the substrate, and mounting chips according to the arranged pattern. A solder ball array on the opposite side of the substrate is routed to the chips, and the flexible substrate and stiffener are folded to align the chips in the stacked die package. The stiffener is removed by a single saw cut.

Abstract: A stacked semiconductor device is formed with a first mounting substrate, e.g., a single metal layer die tape, having a first semiconductor die attached thereto and a second mounting substrate, e.g., a double metal layer die tape having a second semiconductor die attached thereto. Substantially columnar solder connections, each formed from two solder balls are used to stack the first mounting substrate and the second mounting substrate such that the second semiconductor die is positioned between the mounting substrates. For example, identical memory dice may be stacked in this manner or different types of die such as a processor die and a memory die may be stacked in this manner for use in implantable medical apparatus.

Abstract: A stacked semiconductor device is formed with a first mounting substrate, e.g., a single metal layer die tape, having a first semiconductor die attached thereto and a second mounting substrate, e.g., a double metal layer die tape having a second semiconductor die attached thereto. Substantially columnar solder connections, each formed from two solder balls are used to stack the first mounting substrate and the second mounting substrate such that the second semiconductor die is positioned between the mounting substrates. For example, identical memory dice may be stacked in this manner or different types of die such as a processor die and a memory die may be stacked in this manner for use in implantable medical apparatus.

Abstract: A twisted nematic liquid crystal material used in a dual-frequency addressable liquid crystal cell is disclosed. Specific materials include an eutectic mixture of 2-5 monoester compounds having the formula R--X--Y--CO.sub.2 --Z--R', wherein R and R' is a straight alkyl having 2-7 carbon atoms and where each of X, Y and Z is a phenyl or trans-cyclohexyl and at least one of X, Y and Z is a trans-cyclohexyl. Also included are up to 25 weight percent of dopants to reduce viscosity and up to 10 weight percent of additives to lower the cross-over frequency, the additives being of the formula: ##STR1## wherein X is selected from the group consisting of: ##STR2## wherein R is a straight alkyl having 2-7 carbon atoms.