Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1999-07-30
2001-02-06
Arbes, Carl J. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S840000, C029S846000
Reexamination Certificate
active
06182359
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to a manufacturing process for printed circuits that includes a machining step for shaping a design for the printed circuit with maximum safety and efficiency. More specifically, the invention refers to a technology change in the manufacture of printed circuits that is most useful in making the type to be integrated into service boxes within vehicles.
Manufacturing processes, such as the ones disclosed in the Spanish Patent No. P9200325, which has common ownership with this application, are known. The increase in performances and therefore in the functions offered to a vehicle user requires a continuous improvement in quality, cost-effectiveness and size of the service boxes that contain the printed circuits. The size of the service box must be increased if there is a desire to follow with the practice of integrating the entirety of the printed circuits, plus the functions entrusted to the same, within a single service box.
All that has as a consequence that the space problem is most relevant. Even if the advancement in the integration of printed circuits as is disclosed in Spanish Patent No. P9501610 (having common ownership with this application) are important, the functions and performances mentioned above are still growing, since manufacturers are increasingly offering, even in compact cars or relatively lower-cost vehicles, performances and functions that were previously offered only in top class models.
Conventional procedures for manufacturing printed circuits start basically with a dielectric support, made of epoxy resins and glass fibers or the like. A copper plate is adhered to the dielectric support and the copper plate surface is covered with an anti-acid substance. The covered copper surface is then subjected to a chemical attack. The design of the cover ensures that the desired zones form a series of conductive tracks in the copper plate. Subsequently corresponding mechanizing with inserting machines introduces the chemically treated plates between the printed circuit thus forming components of any type and, in certain cases, forming an architecture on the bases of folding the plates by methods known as shown for example in Spanish Patent No. P9200325, and/or sewing with pins, either short and/or long as is known in the art.
The improvement degree on such circuits has arrived, no doubt and in some technical aspects from the use of increasingly greater copper plate thicknesses in order to be able to support in a smaller space equal or greater intensities. That way, the same surface of the printed circuit can integrate a greater number of elements, and therefore functions, all with the above-mentioned goal of being able to keep all the printed circuits in a reduced space (i.e., the service box).
The manufacturing of the tracks and therefore that of the inter-tracks and the space formed between two conductive tracks on the basis of the conventional technique (i.e., that of the chemical attack) produces certain grooves, formed by vertical walls that are not perpendicular to the top surface of the copper plate. This shortcoming of the prior art is that the inter-tracks form inclined planes on the side walls producing a loss of about three percent to four percent of the conductive surface. The percentage of loss tends to increase when further copper thicknesses are used in such circuits, as disclosed for example, in Spanish Patent No. P501610 (having common ownership with this application).
As can be seen in
FIG. 6
, with conventional methods of printed circuit manufacturing, a copper plate is adhered over a dielectric support
116
. The copper plate is covered in the areas where the chemical attack is not desired. Producing the chemical attack over the copper plate results in the corresponding tracks
115
and the grooves or inter-tracks
113
having walls in the shape of inclined planes. The distance between tracks in the lower part of the grooves, where there is the interface between the copper plate with the dielectric substrate, has a smaller width than in the upper part of the same.
The result of the production of the grooves
113
with inclined walls, as shown in
FIG. 6
, is better seen in
FIG. 7
, which illustrates how a volume
118
of the conductive track
115
is lost. The amount of volume that is lost results from the loss of material coming from the simple product of the height “d” of the material by the width “c” by the length of the track
115
.
It is therefore desirable to provide a printed circuit manufacturing process that meets the needs of modern systems while avoiding the shortcomings and drawbacks of the prior art described above.
SUMMARY OF THE INVENTION
In general terms, this invention is a manufacturing process for making printed circuit boards. The process begins with taking a copper plate and machining grooves into the plate in accordance with the desired design of the printed circuit. A dielectric material is then injection molded onto the conductive plate so that the dielectric material fills the grooves that have been machined. This results in a two layer assembly of the dielectric on one side and the conductive material on the other side. The exposed conductive material is then subjected to one of three processes to form grooves that coincide with the grooves that were previously machined. The three processes can include a conventional chemical attack, chemical machining or cutting. The process results in tracks and grooves having better geometric characteristics than those accomplished with the prior art.
The object of the present invention is that of introducing a new way of manufacturing printed circuits, in order to be able to absorb the losses of the three percent or four percent that happen when manufacturing printed circuits with traditional methods. Further, this invention simplifies the manufacturing of printed circuits on the base of grouping a series of operations in a single assembly. This allows some of the manufacturing operations to be performed in the plant of the printed circuit manufacturer itself. Further, this invention eliminates the need for the techniques of forming a negative of the desired configuration and the later, chemical attack used in the prior art. Therefore, this invention provides a gain in manufacturing speed and utilizes processes with no adverse consequences for the environment.
Other details and characteristics of the invention will be manifest through the reading of the detailed description given below, in which reference is made to the figures attached to the description. These details are given as an example, referring to a case of a practical embodiment, that is not limited to the details outlined. Therefore the following description must be considered from an illustrative point of view and with no limitations whatsoever.
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International Preliminary Examination Report.
Arbes Carl J.
Brooks & Kushman P.C.
Lear Automotive Dearborn Inc.
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