Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-03-30
2001-08-28
Mayes, Curtis (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S230000, C156S247000, C156S248000, C156S256000, C216S043000, C029S846000
Reexamination Certificate
active
06280555
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
Summary of the Present Invention
This invention relates to a method of forming a printed circuit board, and especially to a method that can be used to build printed circuit boards without special tooling or equipment. The invention is particularly applicable to the fabrication of prototype circuit boards or circuit boards for relatively low volume production (where tooling expense is a major factor).
Circuit boards produced by a mass production process, on a large volume scale, can be fabricated with special tools and dies configured to the particular circuit design that is to be used. However, in many experimental situations it may not be economically feasible to construct special tools and dies. The present invention is concerned with the situation where the circuit designer may want to produce limited numbers of printed circuit boards to meet low volume requirements, or for experimental or prototype purposes.
The present invention relates to a method of forming a printed circuit board, without the use of expensive dies or equipment, thereby minimizing the expense of circuit boards used on an experimental or prototype basis.
In practice of the invention, a circuit pattern is cut out of a flexible (or rigid) sheet of plastic material. Using an adhesive tape, the pattern is transferred to a circuit board having a conductive film thereon. After the tape is removed from the pattern, the exposed areas of the conductive film are removed, as by acid etching. The pattern is then removed form the remaining (unetched) areas of the conductive film, leaving a conductive film of.a desired configuration on the dielectric board.
The process can be performed without special skills or equipment, if desired. Alternately, special cutting equipment (e.g. a computer-controlled laser cutter) can be used to form the pattern. The process lends itself to a certain degree of versatility in the type of equipment that can be used.
Specific features and advantages of the invention will be apparent from the attached figures and description of a method embodying the invention.
In summary, and in accordance with the above discussion, the forgoing objectives are achieved in the following embodiment.
1. A method of forming a printed circuit on a board comprising:
a. providing a circuit pattern on a conductive film on a circuit board;
b. removing exposed areas of the conductive film so that the remaining portion of the conductive film has the same configuration as the pattern; and
c. removing the pattern from the conductive film.
2. The method, as described in paragraph 1, wherein the step removing exposed areas of the conductive film involves the application of an etching material to the conductive film.
3. The method, as described in paragraph 1, wherein the step of providing a circuit pattern on the conductive film involves cutting a circuit pattern out of a flexible sheet, and transferring the pattern onto the conductive film.
4. The method, as described in paragraph 3, wherein the step of transferring the pattern onto the conductive film involves pressing an adhesively-coated tape onto the pattern, transferring the tape and pattern into a position overlying the conductive film, pressing the tape and pattern against the conductive film, and removing the tape from the pattern.
5. A method of forming a printed circuit on a dielectric board comprising:
a. cutting a circuit pattern out of a flexible sheet, wherein said sheet has a first contact adhesive on a first major face thereof;
b. pressing a tape against a second major face of said pattern, wherein said tape has a second contact adhesive on the tape surface that is engaged with the pattern;
c. pressing the tape and pattern against a conductive film on a dielectric circuit board, whereby said first contact adhesive secures the pattern to the conductive film;
d. separating the tape from the pattern leaving the pattern on the conductive film;
e. etching exposed areas of the conductive film, to form a conductive layer underneath the pattern; and
f. removing the pattern from the conductive layer.
6. The method, as described in paragraph 5, wherein the first contact adhesive is stronger than the second adhesive.
7. The method, as described in paragraph 5, wherein said circuit board is formed out of a rigid plastic material, and said conductive film is copper.
8. A method of forming a printed circuit on a dielectric board, comprising:
a. applying a first contact adhesive to a first major surface of a flexible masking sheet;
b. temporarily attaching the masking sheet to a glossy surface by bringing the adhesive surface of the sheet into engagement with the glossy surface;
c. cutting a circuit pattern out of said masking sheet;
d. removing areas of said masking sheet, leaving a pattern on the glossy surface;
e. providing a tape having a second contact adhesive on one of the tape major surfaces;
f. bringing the tape into contact with the pattern so that the second contact adhesive is engaged with the exposed surface of the pattern;
g. lifting the tape and pattern off the glossy surface;
h. providing a dielectric circuit board with a conductive film on a major surface of the board;
i. transferring the tape and pattern to the circuit board by bringing the adhesive surface of the pattern into engagement with the conductive film;
j. removing the tape from the pattern, leaving the pattern adhesively attached to the conductive film;
k. etching the exposed areas of the conductive film, to form a conductive layer underneath the pattern; and
l. removing the pattern from the conductive layer.
9. The method, as described in paragraph 8, wherein the first contact adhesive is stronger than the second contact adhesive.
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Irving Skeist, editor, “Handbook of Adhesives” Third Edition, pp. 336, 641, 659-660, 1990.*
Encyclopedia Britannica, articles on contact adhesives and pressure-sensitive adhesives, britannica.com, 2001.
Cantor, Esq. Frederick R.
Mayes Curtis
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