Electrolysis: processes – compositions used therein – and methods – Electrolytic coating – Coating moving substrate
Reexamination Certificate
2001-03-22
2003-05-06
Nguyen, Nam (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Electrolytic coating
Coating moving substrate
C204S213000, C204S212000
Reexamination Certificate
active
06558524
ABSTRACT:
This application claims priority under 35 U.S.C. §§ 119 and/or 365 to Japanese Patent Application No. 2000-093878 filed in Japan on Mar. 30, 2000; the entire content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to plating equipment, and more specifically relates to a plating barrel for plating objects such as electronic devices, etc., by immersing a barrel containing the objects into a plating solution and by applying a current.
2. Description of the Related Art
A plating barrel is used for plating a metal layer onto objects such as electric components.
FIG. 4
is a schematic view of an example of a plating barrel of the conventional type.
This plating equipment comprises a barrel
21
which includes a part constructed of a mesh screen, etc., for allowing a plating solution to pass through, and cathodes
22
are placed in the interior of the barrel
21
. First, a quantity of objects (not shown) such as multilayer ceramic capacitors and conducting media (not shown) such as steel balls are placed in the barrel
21
. Then the barrel
21
is immersed into a plating solution
24
contained in a plating bath
23
. Then, a current is applied between an anode
25
which is placed into the plating solution
24
and the cathodes
22
, which are placed inside the barrel
21
, while the barrel
21
is rotated in the plating solution
24
. Accordingly, the objects are brought into contact with the plating solution
24
and the cathodes
22
via the conductive media, and are plated.
In the above-described plating barrel of the conventional type, the objects and the conductive media tumble inside the barrel
21
due to the rotation of the barrel
21
. However, since the end surfaces
21
a
of the barrel
21
are flat and are vertical, the objects tend to accumulate at the end surfaces
21
a
so that the objects are no longer in contact with the conductive media. Thus, there is a problem where the thickness of the plating layers on the objects has a large variation.
In addition, cathode-lead connections
26
for connecting to the cathodes
22
in the barrel
21
have generally horizontal portions, which allows the objects to piled up on top of the cathode-lead connections
26
. This causes another problem where the objects on the cathode-lead connections
26
may not be plated at all, and plating defects may occur.
SUMMARY OF THE INVENTION
The present invention aims to solve the above-mentioned problems. Accordingly, an object of the present invention is to provide a plating barrel which prevents the objects from piling up or stopping in order to avoid the occurrence of plating defects, and which reliably forms a plated layer having uniform thickness on each of the objects.
To attain the above-described object, a plating barrel according to one aspect of the present invention comprises a barrel which is rotatable, has an approximately cylindrical shape, and contains objects inside it, at least one cathode-lead connection which penetrates through the end surface of the barrel along the rotational axis of the barrel and which is supported in a manner such that the cathode-lead connection is rotatable relative to the barrel, at least one cathode which is placed inside the barrel and which is connected to the end of the cathode-lead connection, and at least one either conical or pyramidal attachment which is attached to the cathode-lead connection, in a manner such that the central axis of the attachments are the same as the rotational axis of the barrel, the vertices of the attachments point to the center of the barrel, and peripheral portions of the bases of the attachments at the opposite ends relative to the vertices are in proximity to the inside end surfaces of the barrel, so that the objects do not pass through the gaps between the bases and the inside end surfaces of the barrel. Thus, the piling up or stopping of the objects is avoided or prevented, so that a layer having a uniform thickness is reliably formed on each of the objects and plating defects are prevented.
In order to avoid and prevent the objects from piling up, the conical or pyramidal attachments preferably have vertices having an angle q (see
FIG. 1
) which is larger than 90°, so as to be an obtuse angle.
In the present invention, there are no restrictions regarding the actual shape of the attachments. The attachments may be exactly conical or pyramidal; or, the shape of the attachments may be modified somewhat. For example, the vertices of the attachments may be rounded, or they may be flattened to form a trapezoidal cross-section cone.
A plating barrel according to another aspect of the present invention comprises a barrel which is rotatable, has an approximately cylindrical shape, and contains objects inside it, at least one cathode-lead connection which penetrates through the end surface of the barrel along the rotational axis of the barrel and which is supported in a manner such that the cathode-lead connection is rotatable relative to the barrel, at least one cathode which is placed inside the barrel and which is connected to the end of the cathode-lead connection, and at least one either conical or pyramidal attachment which is attached to the barrel in a manner such that the central axes of the attachments are the same as the rotational axis of the barrel, the vertices of the attachments point toward the center of the barrel, and peripheral portions of the bases of the attachments at the opposite ends relative to the vertices are in contact with or in proximity to the inside end surfaces of the barrel, so that the objects do not pass through the gaps between the bases and the inside end surfaces of the barrel. Thus, from piling up or stopping of the objects is avoided or prevented, so that a layer having a uniform thickness is reliably formed on each of the objects and plating defects are prevented.
Since the conical or pyramidal attachment is attached to the barrel, the attachment rotates along with the barrel, so that the piling up or stopping of the objects is more effectively avoided or prevented.
A major part of the cathode-lead connection is preferably placed in the lower section of the barrel, i.e., below the rotational axis of the barrel.
When the major part of the cathode-lead connection is placed at a lower section of the barrel relative to the rotational axis of the barrel, the objects which pile up in the lower section of the barrel effectively contact the cathodes, which enhances the effectiveness of the present invention.
The conical or pyramidal attachment preferably covers nearly all of the horizontal portion of the cathode-lead connection so as not to expose the generally horizontal portion inside the barrel.
Since the conical or pyramidal attachment covers the generally horizontal portion of the cathode-lead connection so as not to expose the esentially horizontal portion inside the barrel, the objects cannot pile up on the generally horizontal portions of the cathode-lead connections. Accordingly, plating defects in which the objects are not completely plated with uniform thickness layers are effectively prevented.
REFERENCES:
patent: 1563041 (1925-11-01), Puriton
patent: 3099275 (1963-07-01), Pianowski
patent: 4378274 (1983-03-01), Childs
patent: 5698081 (1997-12-01), Lashmore et al.
patent: 195 41 231 (1997-05-01), None
patent: 790006 (1958-01-01), None
patent: 55085697 (1980-06-01), None
patent: 63134420 (1986-07-01), None
patent: 09137296 (1997-05-01), None
Hayashi Ken-ichi
Sanada Yukio
Burns Doane , Swecker, Mathis LLP
Nguyen Nam
Smith-Hicks Erica
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