Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
2001-11-13
2002-11-12
Lam, Cathy (Department: 1775)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S1170FF, C174S1170FF, C174S254000
Reexamination Certificate
active
06479762
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printed circuit board that is preferably used for electronic devices such as video cameras.
2. Description of the Related Art
The structure of a prior-art printed circuit board is described below with reference to
FIGS. 4 and 5
. In the figures, an insulating board
21
formed of a flexible material has a rectangular base portion
22
comprising stationary contacts (not shown in any figures) and a leading portion
23
formed generally in the shape of a letter “L” in its entirety.
The leading portion
23
may be formed generally in the shape of a letter “L” in order to avoid contacting with electric parts (not shown in any figures) provided in the electric device, mounting members (not shown in any figures) or the like. The leading portion
23
is provided with a curved portion
23
a
bent in the shape of a letter “L”, cable portions
23
b
connected to both sides of the curved portion
23
a
and formed to be the same as the curved portion
23
a
in width, and a delivery portion
23
c
provided at an end of the cable portion
23
b.
A plurality of trace patterns
24
formed of silver each have a bent portion
24
a
bent in the shape of a letter “L”, straight trace portions
24
b
connected to both ends of the bent portion
24
a
and having the same pattern width as that of the bent portion
24
a,
and a straight connecting portion
24
c
provided at an end of the trace portion
24
b.
The trace patterns
24
are formed on the leading portion
23
by screen-printing in parallel to each other, with the bent portion
24
a
disposed at the curved portion
23
a
of the leading portion
23
of the insulating board
21
, the trace portion
24
b
disposed at the cable portion
23
b
and the base portion
22
, and the connecting portion
24
c
disposed at the delivery portion
23
c,
respectively.
The trace portion
24
b
formed on the base portion
22
is connected to the stationary contacts (not shown in any figures) formed on the base portion
22
as an electrically conductive pattern.
The printed circuit board fabricated as such allows the connecting portion
24
c
provided at the delivery portion
23
c
to be connected with a connector (not shown in any figures), being adapted that an external current flows into the printed circuit board through the connecting portion
24
c
or a current from the printed circuit board is delivered outwardly through the connecting portion
24
c.
To this end, the connecting portion
24
c
is a critical one and therefore a high accuracy is required of the screen-printing at the connecting portion
24
c.
A prior-art method for fabricating a printed circuit board by means of screen-printing is implemented as shown in FIG.
6
. That is, the insulating board
21
is placed and held on a mounting stage
25
, and thereafter a meshed print mask
26
is placed on the insulating board
21
.
Then, silver paste
27
is applied to the print mask
26
, and thereafter a squeezer
28
is moved in the direction indicated by arrow A to form a plurality of trace patterns
24
by printing on the insulating board
21
.
That is, in
FIGS. 4 and 5
, the squeezer
28
is to move along the arrow A.
At this time, the connecting portion
24
c
is first formed by means of printing, then the trace portion
24
b
is printed, and thereafter the bent portion
24
a
is formed by means of printing.
On the other hand, at the time of this printing, the delivery portion
23
c
of the leading portion
23
is located closer to the initial position of the squeezer
28
. In addition to this, the connecting portion
24
c
or part of the trace pattern
24
, formed in the shape of a straight pattern, is printed in a manner such that the squeezer
28
is to move in the direction of this straight pattern.
In other words, the squeezer
28
is moved in the direction of the straight pattern. This makes it possible to considerably reduce patchy portions of the silver paste
27
and thereby provide highly accurate printing at the connecting portion
24
c.
In addition, the bent portion
24
a
or part of the trace pattern
24
is printed in a manner such that the squeezer
28
is moved in a direction generally perpendicular to the direction of the pattern.
At this time, patchy portions
29
(refer to
FIG. 5
) of the silver paste
27
are likely to occur at the bent portion
24
a
due to air bubbles or the like that are produced at the corners of ink-penetrating portions of the print mask
26
for forming the bent portion
24
a.
As the electronic devices are reduced in size, it is required to reduce the size of the printed circuit board. This has lead to a narrower spacing between the trace patterns
24
and a smaller pattern width thereof, which has in turn presented the possibility of causing a break in a narrowed bent portion
24
a
due to the presence of a patchy portion
29
or the like.
The prior-art printed circuit board is provided with the trace pattern
24
having the same pattern reduced in width at both the bent portion
24
a
and the trace portion
24
b.
This presents a problem of causing a break at the bent portion
24
a
due to the presence of a patchy portion
29
or the like upon forming the trace pattern
24
by printing.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a highly reliable printed circuit board that provides reduced breaks at the bent portion of the trace pattern.
As first means for solving the aforementioned problems, the present invention provides a printed circuit board which comprises an insulating substrate and a trace pattern formed by means of screen-printing on the insulating substrate and provided with a bent portion and trace portions connected thereto. The printed circuit board is adapted that the pattern width of the bent portion is wider than that of the trace portions located near both sides of the bent portion.
As second means, the present invention provides the printed circuit board adapted that the trace pattern is formed by means of screen-printing in such a direction as to firstly form the trace portions connected to the bent portion and thereafter to form the bent portion by printing.
Furthermore, as third means, the present invention provides the printed circuit board with the insulating substrate comprising a curved portion and cable portions connected to both ends of the curved portion. The insulating substrate is provided with a plurality of the trace patterns, with the width of the curved portion made wider than that of the cable portion and the bent portion located at the curved portion as well as the trace portion located at the cable portion.
Furthermore, as fourth means, the present invention provides the printed circuit board adapted that a connecting portion having the shape of a straight pattern is provided at one end of the trace portion connected to the bent portion, and the trace pattern is formed by means of screen-printing along the longitudinal direction of the straight pattern.
REFERENCES:
patent: 4880943 (1989-11-01), Kuzuno et al.
patent: 5005105 (1991-04-01), Onodera
patent: 5598627 (1997-02-01), Saka et al.
patent: 5777855 (1998-07-01), Yokajty
patent: 5834704 (1998-11-01), Tanaka
patent: 6001489 (1999-12-01), Miyaake et al.
Alps Electric Co. ,Ltd.
Beyer Weaver & Thomas
Lam Cathy
LandOfFree
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