Etching a substrate: processes – Forming or treating electrical conductor article
Reexamination Certificate
2000-05-25
2001-11-06
Powell, William A. (Department: 1765)
Etching a substrate: processes
Forming or treating electrical conductor article
C216S020000, C216S041000, C438S689000
Reexamination Certificate
active
06312614
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for production of an interposer for mounting a semiconductor element, where the interposer is used in mounting a semiconductor element onto a motherboard.
2. Description of the Related Art
In recent years, electronic devices equipped with semiconductor elements have become increasingly more compact and lightweight, and this trend has led to the development of the chip-size package (CSP) in which the semiconductor element is mounted on a circuit board, termed an interposer (namely, a semiconductor element mounting interposer), that has substantially the same dimensions as the semiconductor element, which package is then mounted on the motherboard.
Semiconductor element mounting interposers of this type are produced in the manner depicted in
FIGS. 3A
to
3
D.
First, on an insulating base film
31
is formed a conducting circuit
34
that includes motherboard connecting electrodes
32
for interconnection with the motherboard, and plated leads
33
providing conduction paths to the motherboard connecting electrodes
32
to permit electroplating of the motherboard connecting electrodes
32
, as in FIG.
3
A. The plated leads
33
are in electrical connection with continuous conductors
31
a
situated at the two edges of insulating base film
31
.
The semiconductor element mounting interposer is also provided with through-holes
35
which lead the motherboard connecting electrodes
32
to a semiconductor element (not shown) on the backside.
Next, the conducting circuit
34
is subjected to a electroplating process to deposit an electroplated metal layer
36
covering at least the motherboard connecting electrodes
32
, as in FIG.
3
B.
Next, using a die, the plated leads are severed by making holes
37
in proximity to the motherboard connecting electrodes
32
so as to make the plated leads
33
as short as possible, as in FIG.
3
C. Where needed, the continuous conductors
31
a
situated at the two edges of the insulating base film
31
are trimmed, as in FIG.
3
D.
The reason for cutting the plated leads
33
in proximity to the motherboard connecting electrodes
32
as in
FIG. 3C
is as follows.
Where the plated leads
33
in electrical connection with the motherboard connecting electrodes
32
on insulating base film
31
have considerable lengthwise extension, since it is in the nature of branches to produce reflection noise, and since it is in the nature of redundant circuits to increase reactance and capacity, the electrical characteristics of the semiconductor element are adversely affected. It is also necessary for the motherboard connecting electrodes
32
to be electrically isolated from one another. Accordingly, to produce the semiconductor element mounting interposer in an efficient manner, electroplating of the motherboard connecting electrodes
32
is followed by a process of making holes
37
in proximity to the motherboard connecting electrodes
32
so as to make the plated leads
33
as short as possible.
However, production of holes with a die produces flash around the edges of the holes, which can in some instances result in unacceptable appearance or impaired performance. In CSP production, the presence of holes on the circuit substrate tends to make resin encapsulation difficult. Further, the mechanical production of holes in a small CSP polyimide base film with good precision and without damage to the base film is not a simple operation. Also, considerable costs are entailed in die fabrication.
SUMMARY OF THE INVENTION
The present invention was developed in view of the problems pertaining to the prior art, and has as an object to provide, in the production of semiconductor element mounting interposer for a CSP substrate or the like, a way to ensure electrical isolation of the motherboard connecting electrodes from one another and to make the plating leads as short as possible, without the need to produce holes mechanically with a die.
The inventors perfected the present invention upon discovering that, in the process of manufacturing a semiconductor element mounting interposer, the aforementioned problems can be solved by using an etching process to trim the plated leads situated on the side of the interposer that will be mounted to the motherboard, and that this can be accomplished using a chemically-etchable patterning resin layer (e.g., an alkali solution-etchable polyimide precursor layer (polyamic acid layer, etc.), photosensitive polyimide layer, or photoresist layer) as an etching resist during etching of the plated leads.
Specifically, the first invention provides a method for production of a semiconductor element mounting interposer for use in mounting a semiconductor element onto a motherboard, comprising the following steps (A) to (G):
(A) forming a conducting circuit that comprises motherboard connecting electrodes for interconnection with a motherboard, and plated leads in electrical connection with said motherboard connecting electrodes so as to permit electroplating of said motherboard connecting electrodes on an insulating base film;
(B) forming a patterning resin layer over said conducting circuit;
(C) etching said patterning resin layer so as to expose the motherboard connecting electrodes and plated leads of said conducting circuit;
(D) masking the exposed plated leads with an electroplating resist layer;
(E) subjecting the exposed motherboard connecting electrodes to an electroplating process so as to deposit an electroplated metal layer over the motherboard connecting electrodes;
(F) removing the electroplating resist layer masking the plated leads to re-expose the plated leads; and
(G) removing the exposed plated leads through etching.
The second invention provides a method for production of a semiconductor element mounting interposer for use in mounting a semiconductor element onto a motherboard, comprising the following steps (a) to (f):
(a) forming a conducting circuit that comprises motherboard connecting electrodes for interconnection with a motherboard, and plated leads in electrical connection with said motherboard connecting electrodes so as to permit electroplating of said motherboard connecting electrodes on an insulating base film;
(b) forming a patterning resin layer over said conducting circuit;
(c) etching said patterning resin layer so as to expose the motherboard connecting electrodes of said conducting circuit;
(d) subjecting the exposed motherboard connecting electrodes to an electroplating process so as to deposit an electroplated metal layer over the motherboard connecting electrodes;
(e) etching said patterning resin layer so as to expose the plated leads of said conducting circuit; and
(f) removing the exposed plated leads through etching.
Other objects and features of the present invention will be described or become apparent from the following disclosure.
REFERENCES:
patent: 5480048 (1996-01-01), Kitamura et al.
patent: 5509553 (1996-04-01), Hunter et al.
patent: 5733466 (1998-03-01), Benebo et al.
patent: 63-18355 (1988-04-01), None
patent: 9-51155 (1997-02-01), None
Arimitsu Yoshio
Kaneda Yutaka
Oliff & Berridg,e PLC
Powell William A.
Sony Chemicals Corporation
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