Ceramic electronic component and production method therefor

Details Ceramic electronic component and production method therefor Ceramic electronic component and production method therefor

2003-08-08

2004-11-30

Thomas, Eric (Department: 2831)

Electricity: electrical systems and devices

Electrostatic capacitors

Fixed capacitor

C361S301400, C361S311000, C029S025420

Reexamination Certificate

active

06826031

ABSTRACT:

TECHNICAL FIELD
The present invention relates to conductor compositions prepared in the form of paste or ink used to form film conductors on a ceramic base material such as a ceramic substrate. The present invention also relates to multilayer ceramic capacitors and other ceramic electronic components produced with the conductor compositions and a method for producing the same.
BACKGROUND ART
In compact and multifunctional electronic products such as mobile telephones, a large number of compact and precise ceramic electronic components such as hybrid ICs, multilayer capacitors, and multichip modules are used.
FIG. 9
shows a schematic diagram of production procedure of a so-called multilayer circuit board
10
(e.g., low temperature sintered chip antenna switch module used for mobile telephones or the like) as a typical example of such highly functional ceramic electronic components.
First, a paste- or ink-like conductor composition (hereinafter, the compositions in these forms are collectively referred to as “conductor paste”) is applied to a sheet-like ceramic substance (green sheet)
11
a
prepared with a doctor blade or the like, and a film conductor
12
e
with a predetermined pattern made of the conducting component of the composition is formed ((A) in FIG.
9
).
Then, a plurality of green sheets
11
a
,
11
b
,
11
c
,
11
d
, and
11
e
(including those in which film conductors
12
b
,
12
c
,
12
d
, and
12
e
having various patterns are previously formed) are pressed while being superposed in such a manner that the film conductors
12
b
,
12
c
,
12
d
, and
12
e
are buried inside ((B) and (C) in FIG.
9
). Thus, a multilayer ceramic base material II provided the film conductors having a predetermined pattern as inner layers (hereinafter referred to as “inner film conductors) can be obtained.
Then, the conductor paste is applied onto the surface (outer surface) of the multilayer ceramic base material
11
, so that a film conductor
13
with a predetermined pattern made of the composition is formed (hereinafter referred to as a “surface film conductor”). Thereafter, the multilayer ceramic base material
11
in which the surface film conductor and the inner film conductors are formed is fired at a predetermined temperature, and thus the surface film conductor
13
and the inner film conductors
12
b
,
12
c
,
12
d
, and
12
e
are printed onto the ceramic base material
11
((D) of FIG.
9
).
After firing, the conductor paste is applied onto the side face (any one of the faces (end faces) adjacent to the surface on which the surface film conductor is formed, which also applies to the following) of the ceramic base material
11
, and a film conductor
14
(hereinafter, referred to as “side film conductor”) having a predetermined pattern is formed. Thereafter, the multilayer ceramic base material
11
is heated so that the side film conductor
14
is fired for printing ((E) of FIG.
9
). In general, nickel (Ni) plating for the purpose of preventing so-called solder leaching (solder penetration) and tin (Sn) plating for the purpose of providing solder wettability (adherence with solder) are performed with respect to the fired and attached surface film conductor
13
and side film conductor
14
((F) in FIG.
9
).
Then, predetermined elements
15
are mounted on the surface of the plated multilayer ceramic base material
11
. This series of processes provides a multilayer circuit board (chip module)
10
((G) in FIG.
9
). Thus, the circuit board as well as other electronic components
2
,
3
, and
4
are mounted in a mother board
5
and thus a further higher order electronic product
1
is assembled ((H) in FIG.
9
).
The conductor composition containing silver (Ag) or an Ag-based alloy in the form of a conductor metal powder (which may be referred to simply as “Ag paste” in the following) is widely used as the conductor paste to form the film conductor in the ceramic electronic component such as the circuit board (chip module)
10
. Ag is less expensive than gold (Au), platinum (Pt), palladium (Pd) or the like, and has a lower electrical resistivity than those metals, so that it is advantageous to use Ag to form film conductors in various electronic components. For example, Japanese Laid-Open Patent Publication No. 8-181514 discloses a method for producing a ceramic electronic component for high-frequency applications characterized in that the Ag paste is used to form the inner film conductors (internal electrodes) and the surface film conductor (external electrode).
In recent years, Ag pastes having better properties than those of a conventional one have been under in-depth development. For example, Japanese Laid-Open Patent Publication No. 11-163487 (Japanese Patent No. 3150932) discloses an Ag paste that can form a film conductor having only a small extent of bending even if it is fired together with ceramic green sheets. Japanese Laid-Open Patent Publication No. 2001-23438 discloses an Ag paste having an improved bond strength with respect to the ceramic base material. Japanese Laid-Open Patent Publication No. 11-111052 discloses an Ag paste having good solder wettability. Japanese Laid-Open Patent Publication No. 2000-265202 discloses a conductor paste that can form a film conductor having a small heat shrinkage ratio during firing and a method for preparing an Ag powder that is the main component of the paste. Japanese Laid-Open Patent Publication No. 9-194668 discloses an Ag paste that can suppress occurrence or progress of solder leaching (typically, dissolution of Ag contained in the film conductor into a solder), that is, has a high resistance to soldering heat. Japanese Laid-Open Patent Publication No. 8-7644 discloses an Ag paste that can form a dense film conductor that is hardly detached from the ceramic substrate.
In the Ag pastes disclosed in the above-described publications, some of general properties that are desirable for the Ag paste to form a film conductor are improved, but they are not developed with individual and specific focus on each of the surface film conductor and the side film conductor of the ceramic electronic component shown in FIG.
9
. Therefore, when a conventional Ag paste was used as it was without any attempt for improvement, it was difficult to achieve both of the following to a high extent: quality improvement required especially for the surface film conductor fired at the same time as the ceramic base material (e.g., improvement of the bond strength or prevention of excessive firing shrinkage stress); and quality improvement required especially for the side film conductor that is applied after the firing and then fired for printing (e.g., suppression of solder leaching or improvement of resistance to soldering heat). Furthermore, the Ag paste serving as one base was not used with sufficient consideration on whether it should be used to form a surface film conductor or a side film conductor by changing the composition as appropriate (including a change of the content ratio of a metal powder of the main component or selection of a substance to be added as a secondary component).
DISCLOSURE OF INVENTION
It is an object of the present invention to provide Ag pastes that can realize the improvement of the quality required for each of two types of film conductor (i.e., surface film conductor and side film conductor) that are applied onto a ceramic base material at different times and fired at different times, and a method for using the Ag pastes to realize such quality improvement (including selecting an appropriate paste of the pastes having different compositions). It is another object of the present invention to provide a ceramic electronic component having improved electrical characteristics and/or mechanical characteristics (typically, a multilayer ceramic capacitor (MLCC) and other multilayer ceramic circuit boards) and a method for producing the electronic component.
The present invention provides improved paste-like or ink-like Ag based conductor compositions (Ag pastes), and provides the following method for producing

Affiliated with

Also associated with

Rating

Ceramic electronic component and production method therefor does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Ceramic electronic component and production method therefor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ceramic electronic component and production method therefor will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3352477