Cutting – Processes
Reexamination Certificate
2000-09-08
2001-08-14
Goodman, Charles (Department: 3724)
Cutting
Processes
C083S175000, C083S685000, C083S690000, C083S698910, C264S153000
Reexamination Certificate
active
06272957
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method for machining features in sheets of material, and more particularly, relates to an apparatus and method which are simple in use and flexible in operation.
In the current manufacture of multilayer ceramic (MLC) substrates for integrated circuit semiconductor package structures, a plurality of ceramic sheets is formed by doctor blading a slurry containing a resin binder, a particulate ceramic material, solvents, and a plasticizer, drying the doctor bladed sheet, and blanking it into appropriate sized greensheets. Via holes are then mechanically punched for forming electrical interconnections through the sheet. Holes may also be punched in the greensheets to form cavities which will eventually hold the integrated circuit semiconductor device. Electrically conductive paste is deposited in the holes, and in appropriate patterns on the surface of the greensheets, the greensheets stacked and laminated, and the assembly subsequently fired at an appropriate sintering temperature.
There are several methods of forming the cavities in the greensheets. One of these is custom machined punch and die sets. While this method is advantageous for manufacturing large numbers of parts, the machined punch and die sets are expensive and require long lead times. In addition, this method is inflexible for manufacturing new cavity designs or moderate numbers of parts.
Another method for forming cavities is an energy beam system such as the electron beam system disclosed in Booke et al. U.S. Pat. No. 5,124,522, the disclosure of which is incorporated by reference herein. Here an electron beam is utilized to machine features in a greensheet. These kinds of systems can easily handle design changes but they involve large capital expenses and long process times. Also of interest is the scanning laser drilling system disclosed in LaPlante et al. U.S. Pat. No. 5,168,454, the disclosure of which is incorporated by reference herein. Again, the laser drilling system has great flexibility but is expensive and throughput of the system is a concern.
It would be desirable to have a system that is more flexible, simpler and less expensive to form cavities.
Kumagai Japanese Published Patent Application JP02-139202, the disclosure of which is incorporated by reference herein, discloses a system for punching holes in a greensheet which consists of a bottom plate, die, silicone rubber platen and ram. When a greensheet is placed between the die and platen, and force is applied by the ram, the platen forces portions of the greensheet into the apertures of the die. The platen itself is eventually extruded into the apertures of the die, thereby displacing the portions of the greensheet and forming holes or apertures in the greensheet. While this system is effective, it is not without its problems. For example, rounding of the greensheets at the holes occurs, i.e., sharp holes are not formed. This rounding is made even worse when thicker greensheets are utilized.
Deshet U.S. Pat. No. 4,856,399, the disclosure of which is incorporated by reference herein, discloses an apparatus very similar to Kumagai above. Deshet, in addition, discloses that the surface of the platen facing the die is heterogeneous in nature, containing localized regions of higher hardness than surrounding areas of the platen. The localized regions of higher hardness aid in the forming of holes with sharper corners in thin sheets. The thin sheets may be metallic or nonmetallic. It is apparent that the sharpness of the holes would depend on the location of the localized regions of higher hardness. In addition, Deshet would still have problems with thicker sheets of material.
Thus, there still remains a need for a punching apparatus and method which are simple in use and flexible in operation that could produce sharp apertures in sheets of material.
Accordingly, it is a purpose of the present invention to have a punching apparatus and method which are simple in use and flexible in operation for making apertures in sheets of material.
It is another purpose of the invention to have a punching apparatus and method for making sharp-cornered apertures in sheets of material.
It is yet another purpose of the invention to have a punching apparatus and method for making sharp-cornered apertures in thin and thick sheets of materials.
These and other purposes of the invention will become more apparent after referring to the following description of the invention considered in conjunction with the accompanying drawings.
BRIEF SUMMARY OF THE INVENTION
The purposes of the invention have been achieved by providing, according to a first aspect of the invention, a flex die punching apparatus comprising:
a first plate;
a die having at least one aperture positioned adjacent to the first plate;
a flexible, extrudable platen positioned adjacent to the at least one aperture of the die and adjacent to at least a portion of the remainder of the die, the flexible, extrudable platen having at least one punch feature corresponding to the shape and position of the at least one aperture of the die; and
a second plate positioned adjacent to the flexible, extrudable platen;
wherein, in operation, when at least one sheet workpiece is interposed between the flexible, extrudable platen and the die and then the first and second plates are forced together, the at least one feature of the flexible, extrudable platen is caused to extrude a portion of the at least one sheet workpiece through the at least one aperture of the die, thereby forming at least one sheet workpiece having at least one aperture corresponding to the shape and position of the at least one aperture of the die.
According to a second aspect of the invention there is provided a flex die punching apparatus comprising:
a first plate;
a first die having at least one aperture positioned adjacent to the first plate;
a second die having at least one aperture positioned adjacent to the first die, the at least one aperture in the first and second dies being in alignment;
a flexible, extrudable platen positioned adjacent to the at least one aperture of the second die and adjacent to at least a portion of the remainder of the second die; and
a second plate positioned adjacent to the flexible, extrudable platen;
wherein, in operation, when at least one sheet workpiece is interposed between the first and second dies and then the first and second plates are forced together, the flexible, extrudable platen is caused to extrude a portion of the at least sheet workpiece through the at least one aperture of the first die, thereby forming at least sheet workpiece having at least one aperture corresponding to the shape and position of the at least one aperture of the first die.
According to a third aspect of the invention, there is provided a method of forming at least one aperture in at least one sheet of material utilizing a flex die punching apparatus, the apparatus having a first plate, a die having at least one aperture positioned adjacent to the first plate, a flexible, extrudable platen positioned adjacent to the at least one aperture of the die and adjacent to at least a portion of the remainder of the die, the flexible, extrudable platen having at least one punch feature corresponding to the shape and position of the at least one aperture of the die, and a second plate positioned adjacent to the flexible, extrudable platen, the method comprising the steps of:
placing at least one sheet of material between the flexible, extrudable platen and the die; and
forcing the first and second plates together, the at least one punch feature of the flexible, extrudable platen being caused by the step of forcing to extrude a portion of the at least one sheet of material through the at least one aperture of the die, thereby forming the at least one sheet of material having at least one aperture corresponding to the shape of the at least one aperture of the die.
According to a final aspect of the invention, there is provided a method of forming at least one aperture in at
Carbaugh, Jr. William Dale
Herron Lester Wynn
Kapfhammer Mark William
LaPlante Mark Joseph
Long David Clifford
Blecker Iran D.
Goodman Charles
International Business Machines - Corporation
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