Etching device

Details Etching device Etching device

1999-09-14

2001-08-07

Mills, Gregory (Department: 1763)

Adhesive bonding and miscellaneous chemical manufacture

Differential fluid etching apparatus

With microwave gas energizing means

C134S12200P, C134S06400P, C015S077000

Reexamination Certificate

active

06270620

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to an etching device. More particularly, the present invention relates to an etching device capable of forming an uniform etchant film.
2. Description of Related Art
Typically, the laminate substrate used to manufacture a printed circuit board is formed by pressing together several doable-sided boards. The double-sided board comprises alternating layers of an insulating layer and two circuit layers. The method of respectively forming the circuit layers on each side of the insulating layer comprises the steps of forming a copper layer on each side of the insulating layer, and then patterning the copper layers by a photolithography process and an etching process to form a circuit layer on each side of the insulating layer, respectively.
FIG. 1A
is a schematic, top view of a double-sided board when copper layers on both sides of the insulating layer are converted into circuit layers by using a conventional etching device.
FIG. 1B
is a cross-sectional view along a line I—I in FIG.
1
A.
As shown in
FIG. 1A
together with
FIG. 1B
, a double-sided board
104
constituting alternating layers of an insulating layer
100
and copper layers
102
a
and
102
b
is provided. After performing a photolithography process, a wet etching process is performed to pattern the copper layers
102
a
and
102
b
. In the wet etching process, the double-sided board
104
is supported by several hollow sheet-type rollers
106
b
and contacts the hollow sheet-type rollers
106
b
through the copper layer
102
b
(as shown in FIG.
1
A). While the wet etching process is performed, the hollow sheet-type rollers
106
b
are driven to roll by axles
106
a
and the double-sided board
104
levelly moves in a direction indicated by an arrow
110
. Additionally, nozzles
114
spray etchant
108
a
onto the copper layers
102
a
and
102
b
. The etchant
108
a
is conically sprayed from the nozzles
114
in a swing fashion at a fixed point or in a to-and-fro horizontally fashion onto the copper layers
102
a
and
102
b
. Aternatively, the etchant
108
a
is sprayed from angled nozzles (not shown) in a swing fashion at a fixed point or in a to-and-fro horizontally fashion onto the copper layers
102
a
and
102
b
. Therefore, a lot of liquid
108
b
corresponding to the nozzles
114
is formed on the copper layer
102
a
to perform the wet etching process.
However, the etchant easily agglomerates to form a nonuniform etchant film
112
on the copper layer
102
a
, such that the thickness of the nonuniform etchant film
112
on the margin of the double-sided board
104
is larger than that in the center of the double-sided board
104
. The appearance is called a fountain effect. Since thickness of the etchant film is nonuniform, the etching rate in the margin region of the double-sided board
104
is different from that of the central region of the double-sided board
104
.
FIG. 2
is a contour diagram of the copper layer
102
a
after the etching process is performed. Obviously, the etchant film
112
in the central region of the double-sided board
104
is relatively thick, so that the etchant used in the central region of the double-sided board is not easily refreshed. Therefore, the etching result in the central region of the double-sided board
104
is relatively poor. Nevertheless, the etchant film
112
in the margin region of the double-sided board
104
is relatively thin, so that the etchant in the margin region of the double-sided board is often fresh. Hence, the etching result in the margin region of the double-sided board
104
is relatively good. Altogether, the thickness of the copper layer
102
a
in the central region of the double-sided board
104
is larger than that in the margin region of the double-sided board
104
.
Conventionally, in order to move the double-sided board
104
along the direction indicated by arrow
110
more easily, several hollow sheet-type rollers
120
(as shown in
FIG. 3
) are disposed on the copper layer
102
a
. But the relative motion between the hollow sheet-type rollers
120
and the double-sided board
104
disrupts the flux of the etchant. Therefore, the etchant film is still nonuniform and the etching result of the copper layer
102
a
is still poor.
Additionally, in order to overcome the problem due to the fountain effect, another conventional etching device is provided, where the etchant is sectorially sprayed with a particular angle onto the double-sided board. Therefore, the etchant on the copper layer agglomerates to form an etchant flax. Moreover, several hollow sheet-type rollers are disposed on the double-sided board to assist the motion of the double-sided board (the cross-section of the device described above is similar to FIG.
3
). However, the relative motion between the hollow sheet-type rollers and the double-sided board disrupts the flux of the etchant. Hence, the thickness of the etchant film is still nonuniform.
SUMMARY OF THE INVENTION
The invention provides an etching device capable of forming a uniform etchant film. The etching device is disposed on a plurality of parallel and coplanar hollow sheet-type rollers used to support a double-sided board, wherein a plurality of first etchant nozzles is disposed under the hollow sheet-type rollers. The device comprises several solid rollers, several rows of second etchant nozzles and several rows of air nozzles. The solid rollers are coplanarly disposed over the hollow sheet-type rollers and are parallel to each other. The adjacent solid rollers comprise an interval, and the intervals are divided into several first intervals and several second intervals. The solid rollers touch the double-sided board to make an etchant film covering the double-sided board more uniform. The rows of second etchant nozzles are disposed over the first intervals and parallel to axes of the solid rollers. The rows of air nozzles are disposed over the second intervals and parallel to the axes of the solid rollers.
As embodied and broadly described herein, the first and the second intervals are alternatively disposed. Additionally, every row of the second etchant nozzles comprises several etchant nozzles and the etchant nozzles spray an etchant with an angle in the corresponding first intervals to form an etchant flux parallel to the axes of the solid rollers. The etchant flux flows from one end of the first interval corresponding to the axis of the solid roller to the other end of the first interval corresponding to the axis of the solid roller. Alternatively, the etchant flux flows from a central portion of the first interval corresponding to the axis of the solid roller to the margin of the first interval corresponding to the axis of the solid roller. Moreover, the the etchant flux in the adjacent first intervals flows in different directions.
Since the solid rollers touch the double-sided board, the etchant sprayed from the rows of the etchant nozzles can uniformly cover the double-sided board. Incidentally, the flux in the adjacent etchant spraying regions flows in different directions, so that the etchant may not agglomerate to manifest the fountain effect. Hence, the thickness of the etchant film on the double-sided board can be effectively decreased and the etching result of the double-sided board can be greatly improved.
Additionally, in some first intervals, the etchant flux flows from the central part to the margin of the first interval corresponding to the solid rollers, so that the thickness of the etchant film in the central part is decreased and the fountain effect can be avoided. Moreover, because air is puffed from the air nozzles sweeping over the double-sided board in the second intervals, the used etchant can be quickly removed. Therefore, the reaction probability between a conductive layer of the double-sided board and the fresh etchant is greatly increased. By sweeping away the etchant, the fountain effect can be avoided and the etching uniformity of the conductive layer is improved.
It is to be understood that bot

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