Multilayer ceramic device

Details Multilayer ceramic device Multilayer ceramic device

2003-02-24

2004-08-31

Summons, Barbara (Department: 2817)

Wave transmission lines and networks

Coupling networks

Electromechanical filter

C333S133000, C257S700000, C257S703000, C257S728000, C257S729000, C257S778000, C257S788000, C361S746000

Reexamination Certificate

active

06784765

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a multilayer ceramic device used in high frequency wireless devices such as mobile telephones, and relates more particularly to a multilayer ceramic RF device.
2. Description of Related Art
Multilayer ceramic devices, and particularly multilayer ceramic radio frequency (hereinafter referred to as RF) devices operating in the RF band, have contributed greatly to size reductions in mobile telephones and other high frequency wireless devices. A typical conventional multilayer ceramic RF device is described below with reference to FIG.
12
and
FIGS. 13A-E
.
FIG. 12
is a section view of a conventional multilayer ceramic RF device having a low temperature sintered ceramic layer
101
and multilayer circuit conductors forming an RF circuit
102
. Also shown in
FIG. 12
are via holes
103
and chip components
105
such as resistors, capacitors, inductors, and other packaged semiconductor chip components. A metal cap
107
shields the various chip components
105
.
The operation of this conventional multilayer ceramic RF device is described next below.
The multilayer circuit conductor
102
electrically interconnects the chip components
105
, and forms intralayer capacitors and intralayer inductors inside the low temperature sintered ceramic layer
101
. Collectively, these various components form an RF circuit so that the device functions as a multilayer RF switch or other multilayer ceramic RF device.
FIGS. 13A-C
are a block diagram showing the configuration of a conventional multilayer ceramic RF device. These individual discrete devices function as a multilayer filter (FIG.
13
A), a surface acoustic wave (hereinafter referred to as SAW) filter (FIG.
13
B), and an RF switch (FIG.
13
C).
It will be noted that the construction described above does not have a sealing resin protecting the surface mounted chip components, or a metal sealant cap (metal cap
107
) sealing a cavity. The resulting problem is that bare semiconductor devices, SAW filters, and other components that must be sealed cannot be incorporated in the RF device. The conventional metal cap
107
shown in
FIG. 12
simply provides an electromagnetic shield and does nothing to seal the device, and the above-noted components therefore cannot be provided.
Furthermore, the above-described device has a single ceramic layer. As taught in Japanese Patent Laid-open Publication (kokai) H4-79601 (U.S. Pat. No. 5,406,235), it is possible to monolithically mold ceramic layers or other dielectric bodies having different dielectric constants as a way to incorporate a built-in high capacitance capacitor and achieve a multiple function device. Such a device can be produced by, for example, monolithically sintered ceramic layers of different compositions. The problem here is that ceramics of different compositions have different contraction and expansion coefficients, and molding by monolithic sintering is therefore very difficult. A parasitic capacitance affecting device characteristics can also form between ceramic layers of different dielectric constants in monolithically molded ceramic devices made from ceramics of different dielectric constants.
SUMMARY OF THE INVENTION
With consideration for the problems described above, it is an object of the present invention to provide a multilayer ceramic device capable of incorporating components such as bare semiconductor devices and SAW filters.
A further object of this invention is to improve device functionality, reduce device size and profile, improve manufacturability, and improve device reliability.
A yet further object of this invention is to improve overall performance of a multilayer ceramic device providing plural functions with optimized circuit design.
To achieve the above objects, a multilayer ceramic device according to the present invention has a first ceramic layer having a first multilayer circuit pattern electrically connected through interlayer via holes; a second ceramic layer having a second multilayer circuit pattern electrically connected through interlayer via holes; and a thermosetting resin sheet disposed between the first and second ceramic layers. The thermosetting resin sheet has a through hole filled with a conductive resin electrically interconnecting the first multilayer circuit pattern in the first ceramic layer with the second multilayer circuit pattern in the second ceramic layer.
The ceramic layers have at least one internal circuit pattern layer, and the circuit patterns are electrically connected through the via holes. The ceramic layers are preferably made from a high dielectric constant material with a dielectric constant of 10 or higher, and a low dielectric constant material with a dielectric constant less than 10. It is noted that the dielectric constant may be similar to relative dielectric constant.
Exemplary high dielectric constant materials include Bi—Ca—Nb—O (dielectric constant=58), Ba—Ti—O and Zr(Mg, Zn, Nb)—Ti—Mn—O.
Exemplary low dielectric constant materials include alumina borosilicate glass (dielectric constant=7), and forsterite ceramics.
Exemplary thermosetting resins include epoxy resin, phenol resin, and cyanate resins.
The ceramic layers of a multilayer ceramic device according to the present invention are preferably made of a multilayer monolithic, low temperature co-fired ceramics (LTCC).
Further preferably, the first and second ceramic layers are in unity with the thermosetting resin sheet. More preferably, the first and second ceramic layers are thermoset together with the thermosetting resin to be in unity.
Yet further preferably, the first and second ceramic layers each have a different dielectric constant.
As noted above, the ceramic layers have different dielectric constants, and the dielectric constant of the thermosetting resin sheet disposed between the ceramic layers is lower than the dielectric constant of either ceramic layer. The construction of the multilayer ceramic device reduces the parasitic capacitance that occurs between ceramic layers of different dielectrics, and improves device characteristics.
Forming a pattern at the interface between the ceramic layer and thermosetting resin sheet also makes it possible to avoid loss and adjust for mismatched impedance occurring between the multilayer circuit pattern and other circuits formed inside the ceramic layers.
It should be noted that there is little interference between patterns formed at the interface to the ceramic layer, and good device characteristics can be achieved, because the dielectric constant of the thermosetting resin is extremely low.
Yet further preferably, a multilayer ceramic device according to this invention has a third ceramic layer having a third multilayer circuit pattern electrically connected through interlayer via holes; and a thermosetting resin sheet disposed between the second and third ceramic layers. The dielectric constant of the first ceramic layer is less than 10; the dielectric constant of the second ceramic layer is 10 or higher; and the dielectric constant of the third ceramic layer is less than 10.
Yet further preferably, the third ceramic layer is substantially as thick as the first ceramic layer, and the second ceramic layer is thicker than the first and third ceramic layers.
Yet further preferably, the thickness of the first ceramic layer is different from that of the second ceramic layer.
Yet further preferably, a land grid array terminal is disposed to the second ceramic layer on a side thereof not facing the other ceramic layer.
This land grid array is used for electrical connection to the circuit board when the multilayer ceramic device is mounted on a circuit board.
Yet further preferably, a thermosetting resin sheet is disposed between the second ceramic layer and the land grid array terminal.
Disposing a thermosetting resin layer between the bottom of the bottom ceramic layer of the device and the land grid array terminals disposed to the same bottom improves the drop strength of the bottom of the ce

Affiliated with

Also associated with

Rating

Multilayer ceramic device does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Multilayer ceramic device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multilayer ceramic device will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3352611