Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-12-28
2003-12-02
Mayes, Curtis (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S242000, C156S250000, C338S0220SD
Reexamination Certificate
active
06656304
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing PTC elements suited for surface mounting.
2. Description of the Related Art
PTC (Positive Temperature Coefficient) elements are known as protective elements for controlling the current which flows through circuits to be protected since their resistance value increases as they give off heat in overcurrent conditions.
PTC elements essentially possess a structure in which the upper and lower surfaces of a flat-plate-shaped PTC material are sandwiched by electrodes; however, in order for these elements to be used in surface mounting, the terminals of the upper and lower electrode need to be together on one surface.
A conventional method for manufacturing such surface mount-type PTC elements involves, as depicted in
FIGS. 4A
to
4
E, sandwiching a PTC material
1
between an upper electrode foil
2
a
and a lower electrode foil
2
b
(FIG.
4
A), forming through-holes
3
, establishing connection between the upper electrode foil
2
a
and the lower electrode foil
2
b
by filling the through-holes
3
with a plating layer
4
(FIG.
4
B), patterning the electrode foils
2
a,
2
b
of the upper and lower surfaces as well as the plating layer
4
(FIG.
4
C), applying an insulating material
5
to the assembly except those portions which are to serve as the electrode terminals on the plating layer
4
(FIG.
4
D), then cutting the assembly along cutting lines L which pass through the through-holes
3
(FIG.
4
E).
This allows an electrode terminal
6
a
of the upper electrode foil
2
a
and an electrode terminal
6
b
of the lower electrode foil
2
b
to be formed on the bottom surface of the PTC material
1
, an electrode terminal
6
a
′ of the upper electrode foil
2
a
and an electrode terminal
6
b
′ of the lower electrode foil
2
b
to be formed on the upper surface of the PTC material
1
, and thereby a PTC element
10
X to be obtained, on which surface mounting can be performed at the upper or lower surfaces of the PTC material
1
(FIG.
4
E).
However, the steps for manufacturing the PTC element
10
X as shown in
FIGS. 4A
to
4
E are complex, and the manufacture costs high. Moreover, the PTC element
10
X is not moulded, which results in poor moisture resistance as well as the risk of ignition when the PTC element gives off more heat than normal.
In response to these defects, proposed is the injection mould method of manufacture, as shown in
FIG. 5
, in which a surface mount-type PTC element
10
Y is manufactured by sandwiching the upper and lower surfaces of the PTC material
1
between the electrode foils
2
a
,
2
b
, forming leads
7
,
8
to allow the electrode terminals
6
a
,
6
b
of the electrode foils to be accessible on one surface of the PTC material
1
, and moulding the whole assembly with a moulding material
9
so as to leave only the electrode terminals
6
a
,
6
b
exposed.
However, even in the procedure for manufacturing of the PTC element
10
Y, once the PTC material
1
has been sandwiched between the electrode foils
2
a
,
2
b,
the leads
7
,
8
need to be laminated thereon, which necessitates a costly increase in the number of manufacturing steps and components. A further problem is that the thickness of the element will increase. For example, if the thickness of the PTC material t
1
is 0.4 mm, the thickness t
2
of each electrode foil
2
a
,
2
b
0.05 mm, the thickness t
3
of each lead
7
,
8
0.2 mm and the thicknesses t
4a
, t
4b
of the mould material
9
on the upper and lower surfaces 0.3 and 0.6 mm respectively, the thickness of the whole PTC element assembly t
0
will be 1.8 mm.
SUMMARY OF THE INVENTION
In an attempt to resolve the aforedescribed problems with the prior art, it is an object of the present invention to reduce the thickness of surface mount-type PTC elements and enable them to be manufactured at lower cost.
The present inventors perfected the present invention as a result of discovering that surface mount-type PTC elements of reduced thickness can be obtained using a streamlined manufacturing process that is economically advantageous, by forming an electrode layer using an electrode foil or the like so as to wrap a flat-plate-shaped PTC material, partially removing the electrode layer to form upper and lower electrodes, then having the electrode terminals thereof be formed on either the upper or lower surface of the PTC material.
In other words, the present invention provides a method for manufacturing a PTC element, comprising the steps of:
forming an electrode layer on a surface of a flat-plate-shaped PTC material, such that it extends over the upper and lower surfaces and at least one side surface thereof; and
removing a portion of the electrode layer to segment it into a region where it is present on either of the upper or lower surfaces of the PTC material and a region where it extends over the upper and lower surfaces as well as a side surface, to form an upper surface electrode and a lower surface electrode of which the terminals are positioned on one of the surfaces of the PTC material.
REFERENCES:
patent: 5488348 (1996-01-01), Asida et al.
patent: 5852397 (1998-12-01), Chan et al.
patent: 6023403 (2000-02-01), McGuire et al.
patent: 6040755 (2000-03-01), Abe et al.
patent: 6223423 (2001-05-01), Hogge
patent: 6242997 (2001-06-01), Barrett et al.
patent: 6311390 (2001-11-01), Abe et al.
patent: 1 041 586 (2000-10-01), None
patent: 60-158602 (1985-08-01), None
patent: 6-275408 (1994-09-01), None
patent: 9-219302 (1997-08-01), None
patent: 10-12404 (1998-01-01), None
patent: A-10-261505 (1998-09-01), None
patent: 10-289806 (1998-10-01), None
Furuta Kazutaka
Iwasaki Norikazu
Mayes Curtis
Oliff & Berridge
Sony Chemicals Corp.
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