Cutting – Two tool pairs – driver for one pair moves relative to driver... – Punch and shear
Reexamination Certificate
2000-02-01
2001-01-30
Rachuba, M. (Department: 3724)
Cutting
Two tool pairs, driver for one pair moves relative to driver...
Punch and shear
C083S531000, C083S556000, C083S098000, C156S250000, C156S510000
Reexamination Certificate
active
06178861
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to a cutting apparatus for separating semiconductor packages, such as ball grid arrays (BGAs) from a substrate wherein the apparatus makes a dual cut at a single station through multiple material layers without creating slivers of material.
BACKGROUND
Certain types of semiconductor packages are fabricated in pre-determined arrays on a substrate, preferably a polyimide tape or film and wherein the packages are encapsulated by an elastomer sealant also deposited on the tape or film. The arrays of semiconductor packages, including the polyimide tape or film substrate structure is secured to a metal frame having a central opening therein such that the packages may be subjected to a cutting operation to cut through the polyimide tape and also through the elastomer sealant layer. Typically, the operation is conducted in two cutting steps at two different stations to completely separate each semiconductor package from the substrate.
The aforementioned prior art method of separating semiconductor packages, particularly micro ball grid arrays (&mgr;BGAs), often introduces errors in the cutting operation due to misalignment of the packages when moved from one cutting station to the next. This action produces slivers or partially cut portions of the package supporting substrate along one or more edges thereof, resulting in costly rework or modification of the packages before they can be further processed. The present invention overcomes the problems associated with prior art cutting methods for separating semiconductor packages from their support structure, as will be described further herein.
SUMMARY OF THE INVENTION
The present invention provides an apparatus and method for cutting semiconductor packages from a substrate support structure for said packages and wherein the cutting operation includes cutting through multiple layers of material at a single station to more accurately define the package edges and to substantially prevent improperly cut edges or slivers of substrate material remaining partially connected to the packages.
In accordance with one important aspect of the present invention an apparatus is provided which includes support structure for supporting an array of semiconductor packages, particularly micro ball grid arrays, wherein multiple packages on the array may be separated from the array substrate film and sealant layers with an accurate cutting action which cuts through the elastomer sealant material as well as the substrate film or tape structure to define the package outline. The array of packages is preferably supported on a carrier frame which is adapted to be supported on a lower die assembly. An upper die assembly is provided with a cutting knife which cuts a rectangular outline of one or more packages by cutting through the elastomer sealant which encapsulates the packages and at least partially cuts through the substrate film or tape in a first part of the operation. A second part of the operation is carried out without removing the array of packages from the lower die assembly by moving a punch part of the lower die assembly upwardly relative to the knife edges to complete the cutting operation. The singulated or separated packages may then be ejected from the upper die assembly for further processing of the packages. The single station cutting method avoids inaccurate cutting of the edges of the semiconductor packages resulting from poor registration of the package arrays in multiple station cutting operations.
In accordance with another aspect of the present invention, a single station semiconductor package cutting or singulation apparatus is provided which includes a punch member which is movable relative to a package support surface and a cutter blade assembly in such a way as to assure that a cut is made completely through multiple layers of material including an elastomer sealant layer and a polymer tape or film layer supporting one or more semiconductor packages. In this way an accurate and complete cut is made to separate or singulate the packages with respect to an array of packages and knife edges of the cutter blades are not required to impact a hard surface during the cutting operation.
The present invention further provides an apparatus for cutting or singulating semiconductor packages and the like wherein an improved arrangement of support structure for a semiconductor package carrier frame is provided and wherein upper and lower die assemblies of the apparatus are advantageously constructed and operated in a manner not appreciated by the prior art.
Those skilled in the art will further appreciate the abovementioned features and advantages of the apparatus and method of the present invention together with other important aspects thereof upon reading the detailed description which follows in conjunction with the drawings.
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Akin Gump Strauss Hauer & Feld L.L.P.
Pryor Sean
Rachuba M.
Semiconductor Technologies & Instruments, Inc.
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