Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
2001-07-02
2003-02-04
Bell, Bruce F. (Department: 1741)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S199000, C204S202000, C204S206000, C204S212000
Reexamination Certificate
active
06514392
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a conducting roller for an electroplating apparatus, more particularly to a two-input type conducting roller which has two ends that accept simultaneously electric current so as to form a uniform-diameter metal coating on a circuit board.
2. Description of the Related Art
Referring to
FIG. 1
, a conventional electroplating apparatus is shown to include pairs of conducting rollers
7
disposed at upstream and downstream sides of an electroplating bath
9
, which contains an electrolyte. A plurality of spray tubes
91
,
92
and roller units
93
are provided inside the electroplating bath
9
. The spray tubes
91
,
92
not only function as anodes as they are connected electrically to a power source, but also spray an electrolyte onto a horizontal circuit board
8
. Each of the roller units
93
includes a plurality of upper rollers
931
and a lower roller
932
to advance the board
8
through the electroplating bath
9
. The upper rollers
932
are arranged such that they will move downward by gravity to place the lowermost upper roller
931
in contact with the corresponding lower roller
932
as soon as the board
8
moves past the inlet
94
and outlet
94
of the electroplating bath
9
, thereby sealing the inlet
94
and the outlet
94
and preventing the electrolyte from leaking and from staining the conducting rollers
7
provided outwardly of the electroplating bath
9
.
FIG. 2
shows one conducting roller
7
, which includes a rotatable conductive roller body
71
that presses against a side surface of the board
8
(see FIG.
1
), and a stationary conducting rod
72
that is inserted into a chamber
711
in a left end portion of the roller body
71
. The chamber
711
has two ends
712
,
713
, which are provided with a pair of bearing members
714
, on which the conducting rod
72
is journalled. The roller body
71
is rotated by means of a gear unit
715
. An annular seal
73
is sleeved on the conducting rod
72
so as to seal the chamber
711
. A conductive liquid
74
is filled in the chamber
711
between the roller body
71
and the conducting rod
72
. As such, electric current can be transmitted from the conducting rod
72
to the roller body
71
via the conductive liquid
74
. The disadvantages of the conducting roller
7
are as follows:
(1) A resistance loss is incurred on the roller body
71
, and increases gradually from the left end to the right end in view of the condition that only a single cathode current input is provided to the left end of the roller body
71
, thereby resulting in an uneven thickness of metal coating on the board
8
.
(2) The conductive liquid
74
is normally made of mercury, which is highly poisonous, thereby resulting in serious environmental protection problems caused during filling and throwing-away thereof. Thus, it is desirable to reduce the amount of the conductive liquid
74
used in the roller body
71
. However, because the conducting rod
72
is relatively long, a substantial amount of the conductive liquid
74
needed to fill in the chamber
711
.
SUMMARY OF THE INVENTION
An object of this invention is to provide a two-input type conducting roller for an electroplating apparatus, which has a constant voltage value at all of the axial positions thereof so as to maintain an even distribution of cathode current to an electrolyte, thereby forming effectively a uniform-diameter metal coating on a circuit board.
Another object of this invention is to provide a two-input type conducting roller for an electroplating apparatus, which needs only a small amount of conductive liquid to be used therein.
According to this invention, a conducting roller is used in an electroplating apparatus, and includes a conductive roller body, which has two diameter-reduced end portions that are journalled within two stationary conductive sleeve units. A conductive liquid is filled within two sealed gaps between the end portions of the roller body and the sleeve units, thereby transmitting cathode current from the conducting sleeve units to the end portions of the roller body.
Because cathode current is input simultaneously to the end portions of the roller body, the voltage value of the roller body is constant at all of the axial positions thereof such that a uniform-diameter of metal coating can be formed on a circuit board.
Furthermore, the sealed gaps are relatively small such that the amount of the conductive liquid required to be used in the conducting roller can be reduced.
REFERENCES:
patent: 2652461 (1953-09-01), Klein
patent: 2921893 (1960-01-01), Smith
patent: 3374165 (1968-03-01), O'brien et al.
patent: 3541083 (1970-11-01), Beemer et al.
patent: 3549506 (1970-12-01), Willingham
patent: 3839606 (1974-10-01), Paradine
patent: 3887776 (1975-06-01), Kanbayashi et al.
patent: 4036337 (1977-07-01), Arjalies et al.
patent: 4199426 (1980-04-01), Voegelin
patent: 5083353 (1992-01-01), Jacques
patent: 5164059 (1992-11-01), Geiermann et al.
patent: 5939677 (1999-08-01), Ko
patent: 6024849 (2000-02-01), Ko
patent: 6309517 (2001-10-01), Condra et al.
Bell Bruce F.
Merchant & Gould P.C.
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