Tool changing – Process
Reexamination Certificate
2002-01-11
2003-05-20
Wellington, A. L. (Department: 3722)
Tool changing
Process
C483S029000, C083S549000
Reexamination Certificate
active
06565496
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the punching of holes in thin sheet materials such as greensheets used in the manufacture of integrated circuit semiconductor package structures and, more particularly, to a method and apparatus for loading punch pins into a gang-punch apparatus which apparatus is used to form holes in a desired pattern in the greensheet thin sheet material.
2. Description of Related Art
In the manufacture of multilayer ceramic (MLC) substrates for integrated circuit semiconductor package structures, a plurality of green ceramic sheets (commonly termed greensheets) are formed by doctor blading a slurry containing a resin binder, a particulate ceramic material, solvents and a plasticizer, drying the doctor bladed sheet and cutting it into appropriate size sheets. Holes, commonly termed vias, are then punched in each of the greensheets in desired circuitry patterns to facilitate forming electrical interconnections through the sheet. Electrically conductive paste is deposited in the holes and in appropriate circuitry patterns on the surface of the greensheets, each of the patterned sheets stacked and laminated, and the assembly subsequently fired at a sintering temperature to form a MLC substrate.
The vias are formed in the ceramic material when the material is in its green state. Prior to being fired, the greensheets are easily deformed and the precision with which the via holes are formed is greatly dependent upon the use of apparatus which minimize distortion or disruption to the structural integrity of the greensheet other than forming the via hole. With the size of electrical components constantly being reduced through technical improvement the positioning of the via holes in the ceramic greensheets is becoming ever more restrictive. Further, with the increase in the quantity of the electronic circuits needed to make the electronic component package, the requirement for a larger number of vias per unit area of substrate is evident.
Large numbers of holes must be punched into a greensheet with a high degree of precision in order to properly position the holes. At the same time, this punching operation must occur very rapidly in order to produce the large numbers of greensheets that are necessary in the mass production of multilayer ceramic electronic components.
One method for punching greensheets is using a gang-punch apparatus. A gang-punch is a punch/die set where all the punches for a particular ceramic greensheet layer are mounted in a rigid plate. The gang-punch is used to punch the entire greensheet (layer) with a single stroke. A gang-punch has very high throughput and is cost effective for very high volume products. Typically a separate gang-punch is used to punch each layer of the MLC package.
A number of attempts have been made to provide a universal “gang-punch” apparatus which will economically and efficiently provide the means to make via openings in each of the different greensheets used to make the MLC product. One type apparatus utilizes an interposer mask which contains hole openings where holes are desired to be punched. In these type apparatus, a plurality of punch elements are arranged in a grid arranged over the greensheet which is covered by the interposer mask. The greensheet is positioned on a die having through openings corresponding to all the punch elements in the punch head. When the punch elements contact the interposer mask as the punch head is moved downwardly, the hole will be punched where the openings occur since the punch element would pass through the openings in the interposer mask and through the ceramic greensheet. In other areas covered by the interposer mask, i.e., where holes are not desired, the interposer mask will stop the punch element and be retracted into the punch head. A progressive gang-punch utilizes steel balls at locations of punches to be punched on the surface of the punch head which when a roller traverses the top of the punch head vias are punched only where steel balls are located.
A particularly desirable low-cost high-density gang-punch is shown in U.S. Pat. No. 6,223,636 assigned to the assignee of the present invention. The disclosure of this patent is hereby incorporated by reference. In this patent, a gang-punch apparatus is provided for punching selected hole patterns in greensheets. The gang-punch apparatus uses a program plate in a punch head which holds punch pins and which program plate is positioned intermediate the non-punching end of the punch pins and a clearance plate wherein punch pins not used for punching a layer of a particular greensheet are retracted during punching. At the other punch pin locations, the punch pins upon activation of the punch apparatus are extended through the lower portion of the punch apparatus through a greensheet and die to form vias in the greensheet. A preferred punch pin used in the gang-punch apparatus comprises an elongated shank or stem having a ball at its upper end and an opposed squarely cut-off lower end. The diameter of the ball is slightly larger than the diameter of the stem and is supported by the upper surface of a guide plate in the gang-punch apparatus to hold the punch pins. The punch pin may be made from any suitable material such as tungsten, tungsten alloy, steel, beryllium, titanium and is preferably a tungsten carbide material.
In general, the gang-punch tools of the prior art, and in particular, the punch tool disclosed in U.S. Pat. No. 6,223,636, utilizes a punch head composed of thin plates loaded with many thousands of precision tungsten carbide punch pins. The typical punch head holds in excess of 40,000 individual punches that must be loaded into the drilled holes in the punch head plates. Due to the high number of punches used and their fragile nature and small size and close fit into the holes in the punch head, it is important that a precision automated device be provided to load each punch pin into the punch head with little or no intervention from an operator.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide an apparatus for loading punch pins into a punch apparatus such as a gang-punch apparatus used for punching vias in greensheets.
It is another object of the present invention to provide a method for loading punch pins into a punch apparatus such as a gang-punch apparatus for punching vias in greensheets.
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, an apparatus for loading punch pins into a punch apparatus, i.e., a gang-punch, wherein the punch pins have an elongated shank of a first diameter and a larger spherical, cylindrical or other type head having a second larger diameter which punch pins are positioned vertically in a grid in a punch pin supply plate. The punch pins are transferred preferably one at a time to a punch pin receiver device which is positioned above the surface of a movable jaw with the lower end of the receiver device proximate the surface of the jaw. The jaw, together with a mating jaw, are then positioned over an opening to be filled in a punch pin holding plate of the gang-punch apparatus. The receiver device is moved over the jaw opening and the punch pin in the device is forced into the punch pin holding plate opening. The above steps are repeated until the desired number of punch pins are transferred to the gang-punch punch pin holding plate.
In another aspect of the invention, a preferred apparatus for loading punch pins into a gang-punch apparatus comprises:
a punch pin supply plate containing a plurality of openings in a grid in which a plurality of punch pins are positioned vertically, the punch pins having an elongated shank of a first diameter and a second larger diameter head which head
LaPlante Mark J.
Long David C.
Weiss Thomas
Blecker Ira D.
Cadugan Erica E.
DeLio & Peterson LLC
International Business Machines - Corporation
Tomaszewski John J.
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