Optics: measuring and testing – Sample – specimen – or standard holder or support
Reexamination Certificate
1999-07-20
2001-10-30
Rosenberger, Richard A. (Department: 2877)
Optics: measuring and testing
Sample, specimen, or standard holder or support
C356S237200
Reexamination Certificate
active
06310685
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention generally relates to a system and method for inspecting a sheet, and more specifically relates to a system and method for inspecting a pattern on a green sheet.
2. Background Art
Chip carriers typically include several layered sheets, and each sheet includes a ceramic having a pattern formed thereon. In one example, the ceramic is silicate and the pattern material is molybdenum. A method of forming such a sheet typically includes forming the silicate; applying, or screening, a molybdenum paste to the silicate, thereby forming the pattern on the silicate; and allowing the sheet to cure. Before the sheet cures, it is typically called a green sheet.
The pattern is often formed on only one side of the sheet. However, the ceramic often includes holes punched therein with the pattern material filling the punched holes. In this way, when the chip carrier is formed, the pattern on one sheet is connected to the pattern on another sheet via the pattern material in one or more punched holes extending between the patterns.
Patterns formed on green sheets sometimes have flaws. For example, the pattern may include a gap, or it may be smeared. Accordingly, after applying the pattern to the green sheet, it is often desirable to inspect the pattern. In fact, the pattern may be inspected several times during the process of applying it. In prior inspection systems, the green sheet was supported on a wire mesh while the pattern was inspected. However, the wire mesh support was problematic because it often damaged the green sheet, such as by smearing the pattern.
DISCLOSURE OF INVENTION
Accordingly, there is a need for a green sheet holding apparatus that will hold a green sheet without harming it, but that will produce sufficient flatness in the green sheet so that it can be inspected. The present invention includes a green sheet holding apparatus for holding a green sheet having a first edge and an opposing second edge. The holding apparatus includes a first member secured to the first edge of the green sheet, and a second member that is secured to the second edge of the green sheet and is moveable relative to the first member. A forcing mechanism connected to the first and second members forces the second member away from the first member such that the first edge and the second edge of the green sheet are forced away from each other and the green sheet is flattened.
In one embodiment, the forcing mechanism includes a housing secured to the first member and a lever arm that forces the second member relative to the housing. The forcing mechanism may also include a cam member rotatably connected to the housing, wherein the cam member has a cam surface connected to the second member such that rotation of the cam member forces the second member away from the first member.
The first member and the second member may each include a porous surface for securing the first edge of the green sheet to the first member and the second edge of the green sheet to the second member. In this embodiment, each porous surface is fluidly connected to a vacuum source, and the first edge of the green sheet is in contact with the porous surface on the first member and the second edge of the green sheet is in contact with the porous surface on the second member. The pressure differential created by the vacuum source secures the first edge of the green sheet to the first member and secures the second edge of the green sheet to the second member.
The green sheet may also include a third edge secured to a third member and an opposing fourth edge secured to a fourth member. In this embodiment, the fourth member is moveable relative to the third member, and the forcing mechanism forces the fourth member away from the third member, such that the third edge and the fourth edge of the green sheet are forced away from each other and the green sheet is further flattened.
The holding apparatus may be included in a green sheet inspection system, wherein the inspection system further includes a light source directing a light onto the green sheet and a camera detecting light from the green sheet.
The invention also includes a method of holding a green sheet, which includes securing the first edge of the green sheet to a first member, securing the second edge of the green sheet to a second member, and forcing the second member away from the first member. This method pulls the first edge and the second edge of the green sheet outwardly, thereby flattening the green sheet. The method may also include securing a third edge of the green sheet to a third member, securing a fourth edge of the green sheet to a fourth member, and forcing the fourth member away from the third member to further flatten the green sheet. Moreover, the method may be part of a method of inspecting a screened pattern on a green sheet, which further includes directing a light onto the green sheet and detecting the light as it emerges from or is reflected from the green sheet.
The foregoing and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.
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Baan Robert L.
Goring James O.
Graboski David Scott
Lankard, Jr. John R.
Muller Kurt R.
Capella Steven
International Business Machines - Corporation
Rosenberger Richard A.
Schmeiser Olsen & Watts
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