Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1999-12-21
2002-05-28
Young, Lee (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S832000, C029S852000, C428S137000
Reexamination Certificate
active
06393696
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing a printed circuit board. Particularly, the present invention relates to a method for manufacturing a packaging type multi-layer printed circuit board, in which in a multi-layer printed circuit having a window region for installing a semiconductor chip, when a metal is plated on an upper board to form a circuit, bonding fingers for being bonded with the semiconductor chip are prevented from being electroplated with a metal.
2. Description of the Prior Art
Recently, according as the high density integrated circuit chips are made to have a high speed and a high function, the circuit board for installing the semiconductor chips has to have a high speed and a high function. Therefore, for the sake of a high speed and a high function, packaging type circuit boards (to directly install the semiconductor chips) are being proposed. Among these packaging type circuit boards, the chip-on-board type circuit board consisting of a plurality of can form a particularly high density circuit, and therefore, this board is calling for a particular attention.
FIG. 1
illustrates a conventional packaging type multi-layer printed circuit board for installing semiconductor chips. As shown in this drawing, this printed circuit board consists of a plurality of, with circuits formed thereon. Except a first copper clad lamina
1
a
which forms the bottom of the circuit board, other
1
b,
1
c
and
1
d
form a window
4
into which a semiconductor chip
7
is to be installed.
In the above described printed circuit board, there are used both-side copper clad laminates(CCL). Accordingly, the copper cladding of the both faces of the CCLs
1
a,
1
b,
1
c
and
1
d
are etched to form circuits. Further, the CCLs
1
a,
1
b,
1
c
and
1
d
are coupled together by adhesive layers
2
a,
2
b
and
2
c
which consist of prepreg. The CCLs
1
a,
1
b,
1
c
and
1
d
are different in their lengths. That is, the window for installing the semiconductor chip is different in its width at different CCLs, and therefore, when the CCLs
1
a,
1
b,
1
c
and
1
d
are coupled together, the window is formed in a multi-step shape.
Generally, the above described multi-layer printed circuit board is manufactured in the following manner. That is, the respective CCLs
1
a,
1
c,
1
c
and
1
d
are prepaid separately, and window regions are formed. Then the CCLs are coupled together by using the prepreg. Therefore, if the window
4
as shown in the drawings is to be formed, the window regions of the respective CCLs have to have different sizes.
In this manner, the window
4
is formed in a multi-step shape. Accordingly, parts of the second CCL
1
b
and the third CCL
1
c
are exposed to the outside. On the exposed portions of the second and third CCLs
1
b
and
1
c,
there are disposed copper or other metal layers
3
a
and
3
b.
These metal layers
3
a
and
3
b
are wire-bonded through a wire
10
to a pad
9
of the semiconductor chip
7
, and therefore, the metal layers
3
a
and
3
b
are called “bond fingers”.
The above described printed circuit board has an advantage such that the wire bonding between the circuit board and the semiconductor chip is done within the window. Therefore, the wire bonding is not exposed to the outside, and therefore, damages are not caused by external impacts or the like.
In the printed circuit board, there are formed through-holes
11
. These through holes
11
are for electrically connecting the upper layers to the lowermost layer, and the insides of the through holes
11
are electroplated with a metal. Further, a metal is electroplated on the upper face of the lowermost layer, i.e., the fourth CCL
1
d,
thereby forming a circuit. Accordingly, when a metal is electroplated on the inside of the through hole
11
and on the upper face of the fourth CCL
1
d,
the metal is also plated within the window. Particularly, the metal is plated on the bonding fingers
3
a
and
3
b,
and therefore, the circuit is liable to be short-circuited so as to cause defects.
In order to prevent the short-circuiting upon plating the bonding fingers
3
a
and
3
b,
when plating a metal on the upper face of the fourth CCL
1
d
to form a circuit, the window has to be blocked, so that the metal cannot intrude into the window
4
.
A method for preventing the intrusion of the metal into the window is illustrated in FIG.
2
. As shown in
FIG. 2
, a dry film
15
is spread on the fourth CCL
1
d
before plating the metal. Accordingly, the metal is plated in a state with the window blocked, and therefore, the bonding fingers are not plated with the metal. However, the dry film
15
has a certain mass, and therefore, in the case where the dry film having a size of 16.7 mm×16.7 mm is spread on the window, the dry film is pulled downward due to its self gravity, with the result that the dry film is ruptured. In order to prevent this rupture, if the dry film is made thicker, then the formation of fine patterns becomes impossible due to the thick thickness.
In another proposal, there is a method of attaching a copper foil on the fourth CCL
1
d
to block the window. In this case, however, the overall treatment cost is increased due to the complication of the copper foil treatment and the etching treatment, thereby leading to the increase of the manufacturing cost.
SUMMARY OF THE INVENTION
The present invention is intended to overcome the above described disadvantages of the conventional techniques.
Therefore it is an object of the present invention to provide a method for manufacturing a printed circuit board, in which a plurality of boards are first worked to form a slot in each of them, then an ink layer is formed within the slot, then a metal is plated, and then, the boards are subjected to a second working, thereby preventing the plating of the metal on the semiconductor installing region.
In achieving the above object, the method for manufacturing a printed circuit board according to the present invention includes the steps of: forming a circuit on each of a plurality of boards; forming a slot in each of the plurality of the boards so as to form window regions having different sizes; filling an ink into the slots to form ink layers; coupling the plurality of the boards together to form a multi-layer circuit board; forming through-holes through the multi-layer circuit board, plating a metal, and etching it; treating the ink layer with a treatment solution such as sodium hydroxide to remove the ink layer; and removing the regions of the plurality of the boards where the slots are not formed, so as to form a multi-step window in the multi-layer printed circuit board.
A semiconductor chip is installed into the multi-step window, and bonding fingers are formed on the board to be wire-bonded to the semiconductor chip.
REFERENCES:
patent: 4465727 (1984-08-01), Fuji et al.
patent: 5106461 (1992-04-01), Volfson
patent: 5695859 (1997-12-01), Burgess
patent: 5886615 (1999-03-01), Burgess
patent: 6090468 (2000-07-01), Shimada et al.
patent: 0412323 (1990-07-01), None
patent: 0552984 (1993-01-01), None
patent: 59-172295 (1984-09-01), None
patent: 60-257196 (1995-12-01), None
Park Keon-Yang
Sun Byung-Kook
Yoon Kyung-Ro
Samsung Electro-Mechanics Co. Ltd.
Smith Sean
Young Lee
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