Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2000-04-27
2001-08-07
Paik, Sang (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C118S724000, C269S021000
Reexamination Certificate
active
06271503
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vacuum fixture incorporating a vacuum suctioning device which may be employed in the manufacture of preferably thin film chip carriers through the intermediary of retaining parts which are to be processed on the surface of a suction plate in a dimensionally compensating operative mode. Moreover, the invention is directed to a process which may be employed in the manufacture of preferably thin film chip carriers which is adhered in a dimensionally compensating manner to the surface of an interposer plate which is supported on a suction plate of a vacuum fixture.
The utilization of vacuum suction devices for the retention components such as workpieces or webs through the intermediary of applying a suctioning force or a vacuum the components which are to be processed, while positioned on a surface, such as while being ground or treated; for instance, semiconductor wafers or the like, is well-known in the technology. In essence, a glass plate which may have apertures of via holes provided therein is positioned on a porous plate, which is constituted of a suitable rigid material, and a vacuum is then applied thereto for retaining the workpieces on the glass plate wherein the vias in the glass plate enable the suctioning effect created by the vacuum to be imparted to the workpieces.
A previous process which was employed in the manufacture of thin film chip carriers resided in the punching of via holes in a continuous polyimide web. Subsequent processes required two high-temperature operations; in effect, sputtering copper and laminating photoresist on the web, prior to exposing circuitry present on the perforated web. The high temperatures created dimensional inconsistencies or distortions in the spacings of the holes in the web, such spacing between the holes generally being employed to orient a glass master utilized for the purpose of exposing a circuit pattern on the polyimide web. Heretofore, one approach which has been employed in order to be able to correct this problem has been through the use of glass masters for circuitry provided with dimensionally compensated artwork to offset terminal distortions caused by the high-temperature operations involved. However, the provision of glass master generation may readily entail expenditures of up to about $2,000.00 for each glass master. Inasmuch as a single thin film chip carrier production facility may require the provision of a few hundred glass masters in a thin film chip carrier production line, this can readily result in overall equipment costs of potentially hundreds of thousands of dollars.
2. Discussion of the Prior Art
Various types of vacuum devices and installations are currently known and employed in industry and in the technology for retaining workpieces or webs in position during various manufacturing processes.
Rohde, et al., U.S. Pat. No. 5,667,128 relates to a work station for processing a flexible membrane through the employment of a platform which supports and heats the flexible membrane during the processing cycle. The platform is equipped with a vacuum arrangement for retaining a workpiece in position, but does not provide for any dimensional compensating relative to the membrane.
Ueda, U.S. Pat. No. 5,417,408 discloses a wafer holding apparatus incorporating a plate member having through-extending bores which communicate with a vacuum source. The drawing of a vacuum is adapted to create a suction effect intended to retain a workpiece consisting of the wafer immobile against the perforated surface of the plate member so as to enable the wafer to be treated while inhibiting any movement relative to the wafer holding apparatus.
Hardy, et al., U.S. Pat. No. 5,343,012 discloses an arrangement for supporting a substrate on a heater block. The heater block is equipped with a vacuum-generating system adapted to be regulated so as to support the substrate on the heater block in a fixed position to facilitate temperature control over a thin film structure which is to be fabricated on the substrate.
Pending, U.S. Pat. No. 5,141,212 discloses a vacuum chuck having a foam surface structure which has a vacuum applied thereto for retaining a workpiece thereon in a fixed position clamped to a metal plate while being processed.
Koyama, et al., U.S. Pat. No. 4,597,228 discloses a porous material plate having a flat surface adapted to have a workpiece positioned thereon, and with a supporting structure for a vacuum suction plate adapted to impart a vacuum to a plurality of suction grooves to impart a retentive suctioning force to the workpiece.
Sekiya, U.S. Pat. No. 4,521,995 discloses a wafer attracting and fixing device, including a porous plate structure communicating with a vacuum source and wherein an upper plate has a workpiece adapted to be positioned thereon and retained in place due to the application of the suctioning effect of the vacuum. A water injecting hole may be employed for injecting water to soak the attracting surface, and wherein the surface tension of the water transfers the wafer constituting the workpiece to the center of the attracting surface, where it then retained by the vacuum.
Although the foregoing U.S. patents are each directed to respectively various types of vacuum apparatus and methods of positioning workpieces for processing; for example, such as wafers or thin film webs on a work or treating surface which is adapted to be in communication with a source of vacuum, there is no provision for compensating for dimensional distortions or inconsistencies and displacement of a hole or pattern spacing of the workpiece or a thin film web or chip carrier caused by high temperature processing cycles.
SUMMARY OF THE INVENTION
Accordingly, pursuant to the present invention, a workpiece constituted of a continuous thin film chip carrier or web; for example, which constituted of polyimide having via holes therein and which has a circuit pattern exposed by a blanket expose machine, is retained in a stationary or fixed position by the inventive vacuum fixture during the pattern exposure cycle. A perforated interposer structure in the form of a perforated plate having an upper surface forming the top surface of the vacuum fixture and which has the polyimide web located thereon, provides for thermal insulation in forming an insulator, as well as processing a thermal expansion rate or coefficient of thermal expansion which is equivalent to that of a porous sintered metal plate of the vacuum fixture, providing a support for the interposer structure. In effect, the interposer is adapted to insulate the thin film chip carrier or polyimide web from temperature rises and serves as an inexpensive and readily disposable component adapted to maintain product cleanliness within a clean or sterile room environment.
A vacuum generating device circulates suctioning air through the porous plate supporting the interposer structure, wherein the porous plate, selectively expands and contracts while a flow of air passes thereto creating the vacuum for retaining the polyimide web on the interposer structure. In order to regulate or essentially drive the expansion and contraction of the porous plate, individual bars which, respectively, extend in an X-direction and a Y-direction and which may also be vertically controllable in a Z-direction are arranged below the porous plate within the framework of the vacuum apparatus, wherein expansions and contractions of the bars due to thermal changes imparted thereto by a temperature controller, transferred to the porous plate, and the resultant displacements due to thermal changes conveyed to the web through the adherence of the vacuum fixture to the web. This will offset any dimensional inconsistencies or distortions in hole patterns in the web and provide for an accurate processing which is not subject to vagaries in the temperature conditions.
Accordingly, it is an object of the present invention to provide a novel vacuum fixture for supporting a workpiece under the effect of a vacuum or sub-atmosphe
Hall Richard Ronald
Marconi Francesco
Nichols Peter Michael
International Business Machines - Corporation
Paik Sang
Schiesser, Esq. William E.
Scully Scott Murphy & Presser
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