Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Ball or nail head type contact – lead – or bond
Reexamination Certificate
2002-01-25
2003-07-08
Nelms, David (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Ball or nail head type contact, lead, or bond
C257S737000, C257S738000, C257S739000, C257S778000
Reexamination Certificate
active
06590293
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an electronic component with high reliability, a manufacturing method of the electronic component, and a manufacturing method of an electronic circuit device.
BACKGROUND OF THE INVENTION
Requests for downsizing, lightening and thinning a portable information terminal such as a portable telephone have recently increased, and thus much related technological development has been performed. An electronic component including a semiconductor component must be therefore downsized and lightened, and an electronic circuit device employing it must be also downsized, lightened, and thinned. Since the electronic component is downsized, area of a connection part between an electrode of the electronic component and a connection terminal of a circuit board decreased. Therefore, new technology is required for securing reliability of the connection part.
A chip scale package (CSP) structure has been developed for downsizing and thinning the semiconductor component, and this technology has been applied to not only the semiconductor component but also a high frequency electronic component.
A peculiar structure and a manufacturing method are developed for the semiconductor component having the CSP structure. For example, Japanese Patent Laid-Open No. 9-237806 and Japanese Patent Laid-Open No. 11-274241 disclose a method of manufacturing such semiconductor components, and a method of connecting these semiconductor components to a circuit board. In this manufacturing method, projection electrodes such as solder bumps or gold ball bumps are formed on connection electrodes of semiconductor components, a resin film for wholly covering the projection electrodes is then formed, the resin film is cured, the surface of the resin film is then polished to expose the surfaces of the projection electrodes, and a semiconductor wafer is divided into the individual semiconductor components. These methods allow extreme thinning and downsizing of the semiconductor components comparing with a semiconductor component having the CSP structure formed by a conventional resin mold method.
Additionally, Japanese Patent Laid-Open No. 9-246905 discloses an electronic component including a surface acoustic wave element. The electronic component includes projection electrodes formed on connection electrodes of the surface acoustic wave element and a lid body for covering an active region of the elastic wave element. This publication also discloses a circuit board on which the electronic component is assembled, and a protective resin for covering the lid body.
A conventional electronic component, a method of manufacturing the electronic component, and a method of manufacturing an electronic circuit device employing it will be described hereinafter with reference to
FIG. 8A
to FIG.
8
E and FIG.
9
.
FIG.
8
A through
FIG. 8E
are sectional views used for illustrating a conventional manufacturing method of the electronic component such as a semiconductor component and the electronic circuit device.
In
FIG. 8A
, large number of semiconductor components (not shown) including circuit elements such as transistors and resistors are formed on a semiconductor wafer
30
A, and projection electrodes
31
are formed on connection electrodes (not shown) of the semiconductor components. The semiconductor wafer
30
A will be subsequently divided into individual semiconductor components along cutting lines
32
.
In
FIG. 8B
, a resin film
33
is formed over the whole surface of the wafer
30
A by a spin coat method so as to wholly cover the projection electrodes
31
. The surface of the resin film
33
formed on the main surface of the wafer
30
A is then polished or ground, thereby exposing the tip surfaces
34
(hereinafter called top parts) of the projection electrodes
31
as shown in FIG.
8
C. Then, the wafer
30
A is diced along the cutting lines
32
, and thus divided into individual semiconductor components
35
.
Then, in
FIG. 8D
, a circuit board
36
having connection terminals
37
and internal wiring
38
is prepared. A vacuum chuck
39
sucks and holds a semiconductor component
35
and positions the projection electrodes
31
onto the connection terminals
37
. Ultrasonic wave is supplied to the vacuum chuck
39
to bond the projection electrodes
31
to the connection terminals
37
.
In
FIG. 8E
, a resin film
40
covers and protects at least a peripheral part of the semiconductor component
35
. The resin film
40
may wholly cover the semiconductor component
35
.
FIG. 9
is a sectional view of an essential part of an electronic circuit device employing an electronic component having a surface acoustic wave element. Internal wiring
42
and connection terminals
43
are formed on a circuit board
41
. The electronic component
44
has the surface acoustic wave element (not shown), and a lid body
46
covers an active region of the surface acoustic wave element and thereby forms a vibration space. A resin film
47
covers them.
The electronic component having the surface acoustic wave element is manufactured by the following processes:
Forming many surface acoustic wave elements on a piezoelectric wafer;
Forming a lid body
46
to cover an active region of each surface acoustic wave element and forms a vibration space;
Forming projection electrodes
45
on connection electrodes; and
Dividing the wafer into individual electronic components.
The projection electrodes
45
of each of the electronic components
44
manufactured by this method are positioned onto the connection terminals
43
on the circuit board
41
, and then ultrasonic wave is applied to the electronic component to bond the projection electrodes
45
to the connection terminals
43
. Then, the resin film
47
covers the peripheral part or the whole of the electronic component
44
, thereby forming the electronic circuit device having the surface acoustic wave element.
In a conventional method of manufacturing a semiconductor component, projection electrodes are formed, the surface of a wafer is coated with resin, and the resin is polished or ground to expose the surfaces of the projection electrodes. The resin film formed on the wafer with a diameter as large as 20 cm is hardly polished or ground uniformly, and a number of processes increases.
The semiconductor components must be stored so as to prevent the top parts of the projection electrodes from being contaminated since the wafer is divided into individual semiconductor components with the top parts of the projection electrodes exposed until the semiconductor components are mounted on the circuit boards. The projection electrodes, upon being made of easily-oxidized metal other than gold, have respective surfaces oxidized.
Methods of manufacturing a conventional electronic component having a surface acoustic wave element and a conventional electronic circuit device also have a problem similar to that of the semiconductor component discussed above. In a method of mounting the electronic component on the circuit board and then protecting the peripheral part with resin, a lid body must be carefully handled because strength of the lid body may be not sufficient in the previous processes.
Additionally, the surface acoustic wave element includes an inter-digital transducer (IDT) electrode and a connection electrode that are made of aluminum film on the main surface of a piezoelectric substrate. The aluminum film is exposed in other region than the region covered with the lid body. A gold ball bump as the projection electrode is formed on the connection electrode made of the aluminum film. Coolant is poured onto the wafer in a dicing process, but the coolant may cause corrosion of the electrode or penetration of water into the lid body.
When LiTaO
3
or LiNbO
3
is used as a piezoelectric wafer, powder generated during dicing may alkalinize the coolant, which may corrode the aluminum film. When the gold ball bump is formed on the connection electrode made of the aluminum film, electrochemical corrosion may occur on the interface between them.
SUMMAR
Moritoki Katsunori
Namba Akihiko
Onishi Keiji
Ho Tu-Tu
Nelms David
Parkhurst & Wendel L.L.P.
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