Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Bump leads
Reexamination Certificate
1999-07-01
2001-11-06
Graybill, David E. (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Bump leads
C257S738000, C257S778000
Reexamination Certificate
active
06313533
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a function element for making a flip-flop connection, a substrate on which such a function element is to be mounted, a method of fabricating a function element, a method of fabricating a substrate on which such a function element is to be mounted, a coupling structure of a function element and a substrate, and a method of coupling a function element to a substrate.
2. Description of the Related Art
There have been suggested various methods of coupling a function element to a substrate, for instance, in Japanese Patent No. 2503735, Japanese Patent No. 2661382, Japanese Unexamined Patent Publication No. 5-36761, Japanese Unexamined Patent Publication No. 6-21149, Japanese Patent No. 2660943, Japanese Patent No. 2655496, Japanese Unexamined Patent Publication No. 9-252027, and Japanese Unexamined Patent Publication No. 7-231113 (Japanese Patent No. 2874570).
FIGS. 1A and 1B
illustrate one of conventional methods of coupling a function element to a substrate with a resin layer having photosensitivity and thermosetting property, being sandwiched therebetween.
FIG. 1A
is a plan view illustrating a pattern of resin formed on a function element, and
FIG. 1B
is a cross-sectional view taken along the line IB—IB in FIG.
1
A.
In a conventional method, a function element
1
(or a substrate) is first formed at a surface thereof with bumps
5
(or electrode pads in the case of a substrate), as illustrated in FIG.
1
A. Then, resin
6
is coated onto the surface of the function element
1
. The resin
6
is exposed to a light and then developed to thereby remove portions of the resin
6
existing above the bumps
5
, as illustrated in FIG.
1
B.
Japanese Unexamined Patent Publication No. 11-67830 has suggested a method of coupling a SAW element to a circuit board with a sealing resin layer being sandwiched therebetween. The sealing resin layer is composed of resin having photosensitivity and thermosetting property. First, the resin is coated onto an active surface of SAW element. Then, portions of resin on pads, bumps, and a vibration transferring section (IDT electrode) are removed by exposure to a light and development. However, a portion of resin is not removed in an area with which an electrode wiring of a circuit board will make contact, when the SAW element is coupled to the circuit board.
Japanese Unexamined Patent Publication No. 10-326798 has suggested a method of coupling a function element to a circuit board with a sealing resin layer being sandwiched therebetween. The sealing resin layer is composed of resin having photosensitivity and thermosetting property. First, the resin is coated onto both an active surface of the function element and a surface of the circuit board. Then, unnecessary portions of the resin are removed by exposure of the resin to a light and development of the resin. Thus, the resin layer is patterned. However, a portion of resin is not removed in an area with which an electrode wiring of the circuit board will make contact and in an area with which passive elements mounted on the circuit board, such as L, C and R, will make contact, when the function element is coupled to the circuit board.
In the above-mentioned methods, it is not unavoidable that a gap which has a width equal to a sum of a height of a wiring layer
9
formed on the circuit board
10
and a height of the bump
5
formed on the function element
1
is generated between the circuit board
10
and the function element
1
after coupling them to each other. Hence, a resin layer
6
which has a thickness enough to fill the gap therewith and which has photosensitivity and thermosetting property has to be coated on either the function element
1
and the circuit board
10
.
In addition, if the resin layer
6
is collapsed by a width equal to a thickness of the wiring layer
9
formed on the circuit board
10
, the resin layer
6
would make contact only with the wiring layer
9
, and would not make contact with the circuit board
10
. Accordingly, it was necessary to apply big pressure to the function element
1
and the circuit board
10
for thermocompression bonding of them.
If a passive element
15
such as L, C and R is mounted on the circuit board
10
, as illustrated in
FIG. 2
, it was necessary to apply a bigger pressure to the function element
1
and the circuit board
10
in order to collapse the resin layer
6
by a width equal to a height of the passive element
15
.
In the methods suggested in Japanese Unexamined Patent Publications Nos. 11-67830 and 10-326798, since a space is produced between a function element and a circuit board after coupling of them to each other, a patterned resin layer formed on either the function element and the circuit board is designed to fill the space therewith. However, when the function element and the circuit board are coupled to each other, extra resin was frequently adhered to the function element and/or the circuit board in an area where device performances of the function element or the circuit board are harmfully influenced by resin of which the resin layer
6
is composed.
FIGS. 4A and 4B
illustrate another conventional method of coupling a function element to a circuit board with resin having photosensitivity and thermosetting property, being sandwiched therebetween.
In this method, as illustrated in
FIG. 4A
, an adhesive resin layer
6
is formed on a function element
1
in such a pattern that the resin layer
6
is selectively removed around bumps
5
formed on electrode pads
3
. Thereafter, as illustrated in
FIG. 4B
, the function element
1
is thermally compressed onto a circuit board
8
to thereby bond insulating portions of the function element
1
and the circuit board
8
through the resin layer
6
, and at the same time, electrically conductive portions of the function element
1
and the circuit board
8
through the bumps
5
and electrodes
9
formed on the circuit board
8
.
Japanese Unexamined Patent Publication No. 10-335373 has suggested a method of coupling a semiconductor device to a circuit board.
First, as illustrated in
FIG. 5A
, electrodes
9
formed on a circuit board
8
are coated with adhesive resin
14
. Then, as illustrated in
FIG. 5B
, a function element
1
and the circuit board
8
are heated, and are coupled to each other in thermal compression. With bumps
5
formed on electrode pads
3
formed at a surface of the function element
1
, being kept in contact with the electrodes
9
formed on the circuit board
8
, ultrasonic wave is applied to the adhesive resin
14
to thereby cure the adhesive resin
14
.
The above-mentioned conventional methods of coupling a function element to a circuit board with resin being sandwiched therebetween are accompanied with following problems.
The first problem is as follows. When, sealing resin having photosensitivity and thermosetting property is coated on an active surface of a function element, and then portions of the resin are selectively removed only on pads and bumps by exposure of the resin to a light and development of the resin, the resin
6
would not make contact with the circuit board
10
, if the resin
6
is not collapsed by a thickness equal to a thickness of the wiring layer
9
formed on the circuit board
10
, or by a thickness equal to a height of the passive element
15
.
In a method of coupling the function element
1
to the circuit board
10
, if resin having much fluidity is selected, such resin might penetrate an area in which the resin
6
is not allowed to exist. Hence, resin having small fluidity is usually selected. As a result, unless a big pressure is applied to the function element
1
and the circuit board
10
, such resin having small fluidity would not be collapsed.
When the function element
1
is to be coupled to the circuit board
10
by thermal compression with such resin being sandwiched therebetween, unless the resin
6
is collapsed, or the wiring layer
9
or the passive element
15
is collapsed, the resin
6
would not make contact with t
Funaya Takuo
Matsui Kouji
Senba Naoji
Graybill David E.
NEC Corporation
Young & Thompson
LandOfFree
Function element, substrate for mounting function element... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Function element, substrate for mounting function element..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Function element, substrate for mounting function element... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2616994