Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
1998-01-09
2001-04-10
Griffin, Steven P. (Department: 1754)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S330000, C264S646000, C264S603000, C277S943000, C427S554000, C427S555000
Reexamination Certificate
active
06214523
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for forming a pattern on ceramic parts. In particular, the invention relates to a method in which radiation is used to form identifying characters by removing unwanted paste material from an unfired ceramic substrate.
BACKGROUND OF THE INVENTION
Because of their excellent mechanical, thermal, and dielectric properties, ceramic materials are widely used as substrates for the production of integrated circuits. A pattern of conductive paste material, corresponding to the desired pattern of conductive pathways, is placed on the surface of a ceramic substrate or module in its green, or unfired, state. The resulting composite is fired to produce conductive pathways on the surface of a sintered ceramic substrate, known as a ceramic module, having high hardness and high mechanical strength. Various electronic devices are added to the module to form an integrated circuit on the surface of the ceramic substrate.
For tracking and quality control reasons, it is necessary to be able to identify and follow an individual ceramic module as it moves through the production process. This requires that each part be “serialized,” that is, each ceramic module must be marked with an identifying characteristic, such as a unique sequence of alphanumeric characters.
The current method of part identification is difficult to use and produces characters that vary in size and shape. A sheet of unfired ceramic, known as a green sheet, is moved on a programmed x-y stage under a pressurized pen assembly mounted on a fixed z-axis. As the x-y table is moved, paste material is forced under pressure through a 1×10
−2
cm (0.004 inch) carbide tip on the pen to write the identifying characters on the green sheet. Because the flow of paste material is hard to control, the identifying characters vary in size and shape and are difficult to read. Thus, a need exists for a method for the serizalation of ceramic substrates that produces uniform identifying characters that are easy to read and which is compatible with the process used for the manufacture of ceramic modules.
SUMMARY OF THE INVENTION
To meet this and other needs, and in view of its purposes, the present invention provides a method comprising:
a) positioning a pad of unfired paste material on an unfired ceramic substrate;
b) removing a portion of the pad of unfired paste material by exposing unwanted regions of the pad of unfired paste material with a beam of radiation, whereby a pattern of unfired paste material is formed; and
c) applying sufficient energy to the unfired ceramic substrate and pattern of unfired paste material to produce a sintered ceramic substrate comprising a pattern of sintered paste material.
In a preferred embodiment of the invention the paste material is conductive paste material. In another preferred embodiment, the pattern of unfired paste material forms identifying characters. Identifying characters formed by the method of the invention have greater clarity and uniformity than characters formed by previous methods. The method is compatible with the process used for the manufacture of ceramic modules.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention.
REFERENCES:
patent: 4345955 (1982-08-01), Bakemans et al.
patent: 4578329 (1986-03-01), Holsappel
patent: 4931323 (1990-06-01), Manitt et al.
patent: 5262614 (1993-11-01), Katayama et al.
patent: 5294754 (1994-03-01), Wu
patent: 5403650 (1995-04-01), Baudrand et al.
patent: 5552574 (1996-09-01), Merlin et al.
patent: 5580473 (1996-12-01), Shinohara et al.
IBM Technical Disclosure Bulletin, vol. 29, No. Dec. 7, 1986.
Kapogiannis Chris T.
Lankard, Jr. John R.
Leino Gerald H.
Vanduynhoven Thomas J.
Blecker, Esq. Ira D.
Griffin Steven P.
International Business Machines - Corporation
Ratner & Prestia
Strickland Jonas N.
LandOfFree
Pattern formation by removal of paste material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pattern formation by removal of paste material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pattern formation by removal of paste material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2500001