U.S. patent application number 11/429062 was filed with the patent office on 2006-09-14 for circuit substrate and its manufacturing method.
Invention is credited to Takaaki Higashida, Seiji Nakashima, Munekazu Nishihara, Takafumi Okuma, Kenichi Sato, Daisuke Suetsugu, Kenichi Yamamoto.
Application Number | 20060202349 11/429062 |
Document ID | / |
Family ID | 27347849 |
Filed Date | 2006-09-14 |
United States Patent
Application |
20060202349 |
Kind Code |
A1 |
Higashida; Takaaki ; et
al. |
September 14, 2006 |
Circuit substrate and its manufacturing method
Abstract
A circuit substrate has a flexible thin film, electric wires
supported on the film, and an electronic component supported on the
film and positioned between the wires so that the wires and the
component are electrically connected serially. Also, a thickness of
the component is less than that of the electric wires.
Inventors: |
Higashida; Takaaki;
(Kadoma-shi, JP) ; Okuma; Takafumi; (Hirakata-shi,
JP) ; Suetsugu; Daisuke; (Uji-shi, JP) ;
Nakashima; Seiji; (Okasa-shi, JP) ; Yamamoto;
Kenichi; (Moriguchi-shi, JP) ; Nishihara;
Munekazu; (Neyagawa-shi, JP) ; Sato; Kenichi;
(Ikoma-shi, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
27347849 |
Appl. No.: |
11/429062 |
Filed: |
May 8, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10300028 |
Nov 20, 2002 |
7084512 |
|
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11429062 |
May 8, 2006 |
|
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Current U.S.
Class: |
257/777 ;
257/E23.177; 257/E23.178 |
Current CPC
Class: |
H01L 2924/19106
20130101; H01L 24/18 20130101; H05K 1/186 20130101; H01L 2224/32225
20130101; H01L 23/5387 20130101; H05K 2201/0317 20130101; H01L
2924/19105 20130101; H05K 2201/09036 20130101; H01L 2224/73204
20130101; H05K 3/4691 20130101; H05K 2201/10037 20130101; H01L
23/5389 20130101; H05K 3/4611 20130101; H05K 2201/10083 20130101;
H05K 1/056 20130101; H01L 2924/12043 20130101; H05K 1/189 20130101;
H05K 3/0058 20130101; H01L 2924/14 20130101; H05K 1/16 20130101;
H05K 2201/0999 20130101; H01L 2224/16225 20130101; H04R 17/00
20130101; H01L 2224/73204 20130101; H01L 2224/16225 20130101; H01L
2224/32225 20130101; H01L 2924/00 20130101; H01L 2924/12043
20130101; H01L 2924/00 20130101; H01L 2924/14 20130101; H01L
2924/00 20130101 |
Class at
Publication: |
257/777 |
International
Class: |
H01L 23/52 20060101
H01L023/52 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 21, 2001 |
JP |
2001-355415 |
Jan 29, 2002 |
JP |
2002-019947 |
Mar 26, 2002 |
JP |
2002-086373 |
Claims
1-25. (canceled)
26. A circuit substrate, comprising: layered organic films each
supporting circuit modules and being electrically and/or optically
connected to each other.
27. A circuit substrate, comprising: layered organic films each
supporting electric circuits having respective function modules,
said electric circuits being electrically and/or optically
connected to each other.
28. A circuit substrate, comprising: layers, each being selected
from any one of a first organic film supporting a circuit with a
function module, a second organic film supporting a thinned
function circuit, and a third organic film supporting a bare chip
function device, with circuits of said layers being electrically
and/or optically connected to each other.
29. The circuit substrate according to claim 28, wherein said
thinned function circuit on said second organic film has a
thickness of at most 10 .mu.m, and each of said first, second and
third organic films have a thickness of at most 100 .mu.m.
30. The circuit substrate according to claim 28, further
comprising: a metal connection for electrically connecting circuits
of different ones of said layers.
31. The circuit substrate according to claim 28, wherein said
second organic film supports a bare chip function device.
32. The circuit substrate according to claim 28, wherein said
function module is for transforming an electric, optical or audio
signal into another signal.
33. The circuit substrate according to claim 28, wherein said
thinned function circuit is a capacitor, inductor or register.
34. The circuit substrate according to claim 28, wherein said
circuit substrate has a thickness of at most 7 .mu.m.
35. A circuit substrate incorporated within a cellular phone,
personal data assistant, computer, identification card, electric
wallet, remote controller or memory card, wherein said circuit
substrate has layers each being selected from any one of a first
organic film supporting a circuit with a function module, a second
organic film supporting a thinned function circuit, and a third
organic film supporting a bare chip function device, with circuits
of said layers being electrically and/or optically connected to
each other.
36. A circuit substrate comprising: layered circuit modules each
including a component for signal transmission and processing, a
circuit, and an electrical and/or optical connector for connecting
said circuit of one of said circuit modules to said circuit of
another one of said circuit modules.
37. A circuit substrate comprising: circuit modules layered one on
top another, each of said circuit modules comprising (i) two
flexible circuit boards each supporting components for transmitting
or processing a signal, and a circuit for connecting said
components, and (ii) a flexible connecting portion formed
integrally with said two flexible circuit boards and supporting a
circuit for electrically and/or optically connecting said circuits
on said circuit boards.
38. The circuit substrate according to claim 37, wherein said
circuit modules are layered so that said connecting portions do not
overlap each other.
39. The circuit substrate according to claim 37, wherein one of
said circuit boards of one of said circuit modules is positioned
above one of said circuit boards of another one of said circuit
modules, and the other of said circuit boards of said one of said
circuit modules is positioned under the other of said circuit
boards of said another one of said circuit modules.
40. The circuit substrate according to claim 37, wherein adjacent
circuit boards of at least two of said circuit modules are at least
in part in contact with or bonded to each other.
41. The circuit substrate according to claim 40, wherein a contact
or bonded area of said adjacent circuit boards is at most 50 % of
an entire area of each of said circuit boards.
42. The circuit board according to claim 41, wherein said adjacent
circuit boards are electrically or optically connected to each
other in said contact or bonded area.
43. A circuit substrate comprising: a first circuit module and a
second circuit module, each of said first and second circuit
modules having first and second circuit boards and a connection
portion for connecting said first and second circuit boards, each
of said first and second circuit boards supporting components for
transmitting or processing a signal, and each of said first and
second circuit boards also supporting a circuit for connecting said
components, with said connection portion supporting another circuit
for connecting said circuits on said circuit boards, wherein said
first and second circuit modules are layered so that said first and
second circuit boards of said first circuit module are layered on
said first and second circuit boards of said second circuit
module.
44. The circuit substrate according to claim 43, wherein said first
circuit board of said first circuit module is placed on or above
said first circuit board of said second circuit board, and said
second circuit board of said first circuit module is placed below
or under said second circuit board of said second circuit
module.
45. A process for manufacturing a circuit substrate having circuit
modules layered one on top of another, each of the circuit modules
having flexible circuit boards each supporting components for
transmitting or processing a signal, each of the flexible circuit
boards also supporting a circuit connecting the components, and
each of the circuit modules also having a flexible connecting
portion integrated with the circuit boards for electrically and/or
optically connecting the circuit boards, comprising: detecting an
operation of the circuits supported on one or more of the circuit
boards of the circuit modules before completing layering of the
circuit modules.
Description
[0001] This application is a divisional of U.S. application Ser.
No. 10/300,028, filed Nov. 20, 2002.
FIELD OF THE INVENTION
[0002] The present invention relates to an electrical circuit
substrate. Also, the present invention relates to a film-like
electrical circuit substrate, e.g., a thinned integrated circuit
substrate, for use with an electronic device or an optical device,
including a multi-layered electrical circuit and functional modules
mounted on the circuit. Further, the present invention relates to
an electrical circuit substrate with a plurality of layered circuit
modules each having flexible circuit boards and connections
integrally formed with the boards for connecting the boards.
BACKGROUND OF THE INVENTION
[0003] Small sized electronic circuits with high performance have
been developed so far. In particular, a multi-functional electronic
circuit capable of being mounted in a small space has been provided
for cellular phones and computers, for example. Simultaneously,
further improvements have been made for effective heat radiation
from circuits and for downsizing thereof.
[0004] FIG. 5 shows a part of a cellular phone. The cellular phone
has a housing 21 in which a circuit board 22 or substrate is
received. The circuit board 22 supports a plurality of electronic
parts 23, a microprocessor (MPU) 24, a speaker 25 and a microphone
26 mounted thereon. With this cellular phone so constructed, a
signal received by an antenna 27 is processed by the microprocessor
24, then transformed into an audio signal by the electronic parts
23, and finally transmitted from the speaker 25 in the form of a
voice. On the other hand, voices collected at the microphone 26 are
transformed into a corresponding voice signal, then processed by
the electronic parts 23 and the microprocessor 24, and finally
transmitted from the antenna 27.
[0005] Disadvantageously, downsizing of electronic devices requires
an elevated performance of heat radiation for the circuit board.
This problem may be solved by an enlargement of the circuit, which
results in an enlargement of the phone. On the other hand, it is
impossible to reduce an area of the circuit board to be less than
that of the electronic parts. In addition, currently used circuit
board 22 and electronic parts 23 are relatively large in
thickness.
[0006] These circumstances provide a great difficulty of downsizing
the cellular phone and result in an increase of its manufacturing
cost. To solve such problems, another idea may be proposed to layer
a plurality of circuit boards. However, this requires longer wires
for electrical connection of electronic parts, which results in a
difficulty of its jitter control.
[0007] Meanwhile, a double-sided circuit board bearing circuits on
opposite surfaces, and a multi-layered circuit board, have been
used for compactness and high performance of a circuit substrate of
electronic and optical devices. In fact, a high density,
multi-layered substrate is employed in a large number of electronic
devices.
[0008] In a process for manufacturing such a multi-layered
substrate, a glass cloth is impregnated with epoxy resin and then
dried to produce a substrate material typically called a "prepreg".
Opposite surfaces of the prepreg are covered with a copper film on
which a dry film is then laminated. The dry film is exposed to
light and then developed to form an etching pattern with which the
copper film is etched. Finally, the dry film is removed from the
prepreg to result in a double-sided circuit board. Double-sided
circuit boards and prepregs are layered alternately and then
integrated by heating and pressing into a multi-layered circuit
board. Subsequently, holes are defined in the multi-layered circuit
board as necessary. Also, an electrically conductive layer is
deposited on an inner surface of each hole, thereby causing
electrically conductive layers mounted on the circuit board to be
electrically connected to each other.
[0009] On a surface of the multi-layered circuit board so
constructed, a variety of functional parts are mounted to form a
specific circuit. Typically, semiconductor chips including an LCR
for signal processing, and also one or more packaged logic devices
for calculation,-are mounted on the surface of the multi-layered
circuit board. Further, in order to add other functions required
for the electronic and optical devices, a plurality of
multi-layered circuit boards can be connected with each other to
form a certain module. Furthermore, a certain functional module
and/or power circuit may be connected for transformation of an
electrical, optical and/or audio signal into necessary information
required for a device.
[0010] FIG. 9 shows a conventional electronic/optical device using
the multi-layered circuit board and the functional modules. As can
be seen from the drawing, the device has a multi-layered printed
circuit board 231, a flexible board 232, a liquid crystal module
233a, an optical camera module 233b, an input touch panel module
233c, a packaged logic circuit 234, a chip-like functional
component 235, a copper wire 236 defined in the multi-layered
circuit board, and through-holes 237 each filled with an
electrically conductive paste for electrically connecting circuits
on respective layers.
[0011] In operation of the device using the multi-layered circuit
board, optical information is captured and then transformed into a
corresponding electrical signal by the optical camera module 233b.
This signal is processed into image data by the logic circuit 234
on a bottom surface of the board. Other information inputted
through the touch panel module 233c is also transformed into a
corresponding electrical signal which is then processed by chip
circuit components on the bottom surface of the board, for example.
This information is then transformed into respective signal data
which is transmitted through the flexible board 232 to another
multi-layered circuit board where it is further transformed by
logic circuit 234 and functional components 235 such as LCDs.
Subsequently, data so transformed is transmitted through
the-flexible board 232 to the liquid crystal module 233a where it
is transformed into a corresponding optical signal and then
displayed in the form of an image.
[0012] As described above, functional devices and components
mounted on opposite surfaces of the multi-layered circuit board are
electrically connected by various wires mounted within and/or
between layers. Also, copper wires 236 (circuit pattern) of
respective layers and an electrically conductive paste 237, filled
into through-holes for connection of the copper wires 236, are
electrically connected with each other to form a three-dimensional
circuit.
[0013] However, in this three dimensional circuit, the functional
components are mounted only on each surface of the layers. This
results in various difficulties with regard to shortening of the
wires between the components and/or modules, and requires a
flexible circuit board, for example, for electrical connection of
the layers, which may cause an adverse affect such as loss and/or
noise during transmission of high frequency signals. Also, chip
components and packaged functional devices are connected to the
board by soldering, for example, which makes it difficult to
increase a performance of an overall circuit due to possible
inaccuracies of the components and their mounting. This further
provides great difficulty with regard to manufacturing of a
high-frequency and high-speed digital device, and accordingly, with
regard to downsizing and high-functionalization of the device.
[0014] FIG. 13 shows a conventional flex-rigid circuit board 301.
The board 301 has an unfoldable rigid portion 302 and a foldable
flexible portion 303. The flexible portion 303 supports a
multi-layered circuit board 304 bearing a conductive circuit 305.
The conductive circuit 305 is covered by a protective film 306
bonded thereon. In the rigid portion 302, a rigid circuit board 308
is layered on and bonded to the multi-layered circuit board 304
using a bonding sheet and/or prepreg 307. Also, in the flexible
portion 303 where the multi-layered circuit board 304 is exposed,
the bonding sheet and/or prepreg 307 and an associated part of the
rigid circuit board 308 are removed therefrom. A plurality of
electronic components 309 are mounted on the rigid circuit board
308 of the rigid portion 302. These components 309 are electrically
connected by through holes 310 running through the multi-layered
circuit board 304 and the rigid circuit board 308.
[0015] As described above, the conventional flex-grid circuit board
301 lacks flexibility in a region including the multi-layered
circuit board 304, which results in great difficulties with regard
to configuration of the circuit board, and accordingly, with regard
to its installation into a housing with curved portions. Also, the
multi-layered circuit board 304 has a certain thickness which
prevents shortening of wires in its direction and fails to meet
high-frequency requirements.
[0016] Further, a number of through-holes should be arranged in a
complex manner for connection of layered circuits, which provides
various restrictions on a circuit design and downsizing of the
circuit board, for example, and increases manufacturing costs of
the circuit board.
[0017] Additionally, according to this conventional multi-layered
circuit board, each layer is fully bonded to an adjacent layer.
Also, only after completion of manufacturing of the circuit board,
is a test performed to confirm whether each layer operates in an
expected manner.
[0018] This is because it can be thought that the multi-layered
circuit board works well only after all the layers have been
fabricated and then connected with each other. This means that no
operational test could be performed until completion of
manufacturing of the multi-layered circuit board, which makes it
difficult to determine or remove defective products during a
process of manufacturing, which results in a decrease of a yield
rate and makes products costly.
SUMMARY OF THE INVENTION
[0019] According to the present invention, an electrical circuit
substrate has a flexible thin film, electric wires supported on the
film, and an electronic component supported on the film and
positioned between the wires without any overlap with the wires so
that the wires and the component are connected serially, and a
thickness of the component is less than that of the electric
wires.
[0020] In another aspect of the present invention, a circuit
substrate has a plurality of films layered one on top of another,
with each film supporting electric wires and an electronic
component electrically connected between the wires, wherein wires
on one film and those on another film are electrically connected to
each other through a connection running between opposite surfaces
of the one or another film.
[0021] In another aspect of the present invention, a circuit
substrate has a plurality of layers each of which is selected from
any one of a first organic film supporting a circuit with a
functional module, a second organic film supporting a thinned
functional circuit, and a third organic film supporting a bare chip
functional device, with circuits on the layers being electrically
and/or optically connected to each other.
[0022] In another aspect of the present invention, provided is a
circuit substrate which is incorporated within a cellular phone,
personal data assistant, computer, identification card, electric
wallet, remote controller or memory card, wherein the substrate has
a plurality of layers each of which is selected from any one of a
first organic film supporting a circuit with a functional module, a
second organic film supporting a thinned functional circuit, and a
third organic film supporting a bare chip functional device, with
circuits on the layers being electrically and/or optically
connected to each other.
[0023] In another aspect of the present invention, a circuit
substrate has a plurality of circuit modules layered one on top of
another. Each of the circuit modules has two flexible circuit
boards each supporting components for transmitting or processing a
signal and a circuit for connecting the components, and a flexible
connecting portion formed integrally with the two flexible circuit
boards and supporting a circuit for electrically and/or optically
connecting circuits on the circuit boards.
[0024] In another aspect of the present invention, a circuit
substrate has a first circuit module and a second circuit module,
with each of the first and the second circuit modules having first
and second circuit boards and a connection portion for connecting
the first and second circuit boards, with each of the first and
second circuit boards supporting a plurality of components for
transmitting or processing a signal and a circuit for connecting
the components, and with the connecting portion supporting another
circuit for connecting circuits on the circuit boards, wherein the
first and the second circuit modules are layered so that the first
and the second circuit boards of the first circuit module are
layered on the first and second circuit boards of the second
circuit module.
[0025] In another aspect of the present invention, a process for
manufacturing a circuit substrate, with the substrate having a
plurality of circuit modules layered one on top of another, and
with each of the circuit modules having a flexible circuit board
supporting components for transmitting or processing a signal and a
circuit connecting the components, and with the substrate also
having a flexible connecting portion integrated with the circuit
boards for electrically and/or optically connecting the circuit
boards, comprises detecting an operation of circuits supported on
one or more circuit modules before a completion of layering of the
circuit modules.
[0026] It should be noted that the present application is based
upon three Japanese Patent Applications Nos. 2001-355415,
2002-019947 and 2002-086373, the entire contents of which are
incorporated herein by reference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is an enlarged cross sectional view of a single-layer
thinned circuit substrate according to a first embodiment of the
present invention;
[0028] FIG. 2 is an enlarged cross sectional view of a multi-layer
thinned circuit substrate according to a second embodiment of the
present invention;
[0029] FIG. 3 is an enlarged cross sectional view of the
multi-layer circuit substrate of FIG. 2 in which a part of the
substrate is deformed;
[0030] FIG. 4 is an enlarged cross sectional view of a multi-layer
circuit substrate according to a fourth embodiment of the present
invention, in which a piezoelectric element is incorporated;
[0031] FIG. 5 is a perspective view of a part of a cellular
phone;
[0032] FIG. 6 is an exploded perspective view of a thinned circuit
substrate according to a fifth embodiment of the present
invention;
[0033] FIG. 7 is a cross sectional view of the thinned circuit
substrate of FIG. 6;
[0034] FIGS. 8A to 8F show specific embodiments of a multi-layer
film device;
[0035] FIG. 9 is a cross sectional view of a conventional
electronic and/or optical device with a multi-layer circuit
substrate and functional modules;
[0036] FIG. 10A is an exploded perspective view of a thinned
circuit substrate according to a sixth embodiment of the present
invention;
[0037] FIG. 10B is a cross sectional view of the thinned circuit
substrate according to the sixth embodiment of the present
invention;
[0038] FIG. 11A is a cross sectional view of a thinned circuit
substrate according to a seventh embodiment of the present
invention;
[0039] FIG. 11B is a cross sectional view of the thinned circuit
substrate according to the seventh embodiment of the present
invention;
[0040] FIG. 12 is an exploded perspective view of a thinned circuit
substrate according to an eighth embodiment of the present
invention; and
[0041] FIG. 13 is a cross sectional view of a conventional
flex-rigid substrate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] With reference to the drawings, various embodiments of the
present invention will be described hereinafter. For clarity of the
drawings, like parts are designated with like reference numerals
throughout the drawings.
First Embodiment
[0043] FIG. 1 shows an enlarged thinned circuit board 101
incorporated in an electronic device such as a cellular phone. As
shown in the drawing, the circuit board 101 has a base 102 made
from a thinned flexile and foldable film. The base 102 has a number
of thinned wires 103 formed on one or both of its major surfaces. A
plurality of components 104, each having a thickness less than that
of the wires 103, are also mounted on the film between the wires
103, i.e., beside the wires, so as not to overlap the wires.
Preferably, the film of the base 102 is made of
polyethyleneterephthalate (PET), polyimide, or polyphenylene
sulfide (PPS). Also preferably, a thickness of the film is about
5-150 .mu.m in order to provide sufficient flexibility to the film.
The film may be a metal film such as aluminum foil. When using
aluminum foil, an insulation layer made of epoxy resin, for
example, may be provided on its surface. This insulation layer is
not necessary if a surface of the film bears an oxide coating
formed thereon.
[0044] The wires 103 are formed by forming a film of conductive
metal on the major surface or surfaces of the base 102 by use of a
known film formation technique such as physical and chemical vapor
deposition, and then etching this metal film. Preferably, a
thickness of the wires 103 is equal to or less than about 3 .mu.m.
Although copper having high conductivity is preferably used for the
metal of the wires 103, other materials such as palladium, gold and
silver may be used instead.
[0045] The components 104 include capacitors, coils, resistors and
transducers, for example, each of which is manufactured on the base
102 by use of a known film formation technique such as physical and
chemical vapor deposition, typically employed during manufacturing
of semiconductor elements. Alternatively, thinned components
already manufactured on another film may be positioned on the base
102 and then electrically connected with associated wires 103 by
soldering. Preferably, in any case, a thickness of the components
is less than about 1 .mu.m.
[0046] As described above, thinned base 102 of the circuit board
101 according to this embodiment supports thinned wires 103 of
elevated conductivity and thinned components 104, which are thinner
than the wires 103, which provides the circuit board 101 with
greater flexibility and thus allows it to follow any configuration
of a housing with ease. Also, the circuit board 101 can be
accommodated within a smaller space than can a conventional rigid
circuit board, which allows further downsizing and weight reduction
of the device. Also, when a portion of the circuit board 101 bears
a component having a thick element such as speaker shown in FIG. 5,
another portion of the circuit board surrounding this element is
curved, allowing the circuit board with the element to be housed
within a small space of the device.
Second Embodiment
[0047] FIG. 2 is an enlarged cross sectional view of a thinned
circuit board of a second embodiment. As shown in the drawing, a
multi-layered circuit board 101A is manufactured by stacking a
plurality of single-layer circuit boards 101 or layers of the first
embodiment. Although the multi-layered circuit board 101A has three
single-layer circuit boards in the embodiment, the number of the
single-layer circuit boards is not limited thereto. Preferably, the
single-layer circuit boards are connected entirely or in part to
each other by use of an insulative adhesive or a suitable connector
such as a clip.
[0048] Components 104 mounted on one single-layer circuit board 101
can be electrically connected with those mounted on an adjacent
single-layer circuit board 101 through electrical connectors 105
defined in either of these two single-layer circuit boards 101. For
example, each electrical connector 105 is defined by a wire portion
107 formed on an inner surface of a through-hole 106 extending
through a single-layer circuit board, or filled in the
through-hole, which may be formed by use of a known semiconductor
manufacturing technique.
[0049] With this arrangement of the multi-layered circuit board
101A, for example, an electrical signal from one component 104 on a
top base 102 or single-layer circuit board is transmitted through
wire or wires 103 and then through the electrical connector 105 of
the top base to another component 104 of a second layer 102 or
single-layer circuit board. This ensures that the signal is
transmitted through a shorter pass, when compared with a
conventional circuit board in which a signal is transmitted through
another pass mounted on an edge of or around the circuit board.
This prevents the signal from picking up possible unwanted noises
and/or disturbances.
[0050] As described above, the thinned circuit board 101A of the
present invention, which is made of thinned base 102 and the
thinned components 104 mounted thereon, minimizes the number of
components to be mounted on the base 102. This causes the circuit
board 101A to be downsized, allowing the circuit board 101A to be
housed within a smaller space and made lighter in weight.
Third Embodiment
[0051] FIG. 3 shows a housing 110 and a multi-layered circuit board
101B received in the housing. In this embodiment, the housing 110
has a surface 111 for receiving the circuit board. This receiving
surface 111 has a deformation such as recess 112 or curved portion
where at least one hole 114 extends between top and bottom
surfaces, 111 and 113, of the housing.
[0052] In order for mounting the circuit board 101B in the recess
112 as illustrated, first a plate like circuit board 101B is placed
on the surface 111 of the housing 110 so that it covers the recess
112. Then, a chamber defined within the recess 112 is connected to
and then vacuumed by a suitable vacuum machine 115, so that
flexible thinned circuit board 101B is deformed by the vacuum
pressure in the chamber to follow an inner configuration of the
recess 112, thereby providing the circuit board 101B with a three
dimensional configuration corresponding to that of the recess
112.
[0053] If the circuit board 101B can easily recover to its original
plane configuration due to its elasticity by elimination of the
vacuum, a peripheral edge of the circuit board 101B is preferably
fixed continuously to the housing 110 by use of a suitable bonding
technique such as heat sealing 116 and use of adhesive. In this
instance, the hole 114 is closed by heating and then deforming a
housing portion surrounding and defining the hole, or by filling a
suitable bonding material into the hole, which permanently
maintains the three dimensional deformed configuration of the
circuit board. If an overall surface of the circuit board, or at
least a portion of the circuit board adjacent to the chamber of the
housing 110, is smooth and does not support any component, no heat
seal is needed. Also, if the circuit board 101B is deformed
plastically beyond its elasticity limit, nothing is required for
retaining this deformed condition. Further, the circuit board 101B
may be deformed to a configuration corresponding to that of the
chamber before it is mounted in the housing.
[0054] As described above, the thinned circuit board is housed
within the housing without any difficulty even when the housing has
a convex and/or concave portion. This ensures that the housing, or
device receiving the housing, is designed freely and also decreases
manufacturing time and cost. Also, performance of the device is
improved.
[0055] Although the circuit board 101B is deformed by use of a
vacuum, such deformation can be performed by a heat press in which
the circuit board is heated and then deformed.
Fourth Embodiment
[0056] FIG. 4 shows another thinned circuit board 101C according to
a third embodiment of the present invention. The circuit board 101C
is featured in that a piezoelectric element 117 is incorporated
into the circuit board so that the piezoelectric element detects a
deformation of the circuit board and then generates a signal
corresponding to an amount of the deformation. The piezoelectric
element 117 is formed on base 102 before or after formation of
wires 103 on the base 102, by use of a known film formation
technique such as physical and chemical vapor deposition typically
employed during manufacturing of semiconductor elements. Also, a
single-layer circuit board in which the piezoelectric element 117
has been formed is stacked on another single-layer circuit board,
each bearing required wires 103, components 104 and connectors 105,
and then bonded thereto, if necessary, to obtain the thinned
circuit board 101C.
[0057] In operation of the circuit board 101C so constructed, if
the base is deformed by any external force or energy, the
piezoelectric element 117 follows this deformation. In the
piezoelectric element, deformation is changed into a signal having
a voltage corresponding to an amount of deformation, which is
transmitted from an associated wire. If the force or energy is
eliminated, the base returns to its original state and an output
voltage of the piezoelectric element 117 returns to that before the
deformation.
[0058] Therefore, the piezoelectric element 117 can be used as an
audio component of a speaker and microphone. This means that the
speaker and microphone can be downsized. On the other hand, the
piezoelectric element 117 can be used as a vibration generator or
vibrator. In this instance, the piezoelectric element may be
located on opposite sides of an axis so that it expands and
contracts and thereby rotates about the axis in response to on/off
operation of voltage, so as to minimize a difference between actual
deformation and calculated deformation derived from a deformation
versus voltage relationship.
[0059] Although deformation of the circuit board is detected by the
piezoelectric element 117, the piezoelectric element may be
replaced by a spring switch, for example.
Fifth Embodiment
[0060] A fifth embodiment relates to another thinned circuit board,
i.e., an integrated circuit structure made of film-like devices.
This thinned circuit board has film layers each being one of three
organic films, i.e. a first organic film supporting a circuit with
at least one functional module, a second organic film supporting a
thinned functional circuit, and a third organic film supporting a
circuit with functional devices like bare chips, in which the
circuits on the films are electrically and/or optically connected
to each other.
[0061] Referring to FIGS. 6 and 7, the circuit board has a
plurality of films positioned one on top of another. The films
include an organic film 201 supporting functional modular circuits,
an organic film 202 supporting thinned functional components and
bare-chip devices, an organic film 203 supporting functional
modular circuits and thinned functional circuits, a transparent
protective film 204, a bonding film 205 and a protective film 206.
In the drawings, thinned functional modules, the functional circuit
components and bare-chip functional devices are indicated by
reference numerals 207a-207i, 208a-208c and 209, respectively.
Also, metal connections for electrically connecting circuits on
different films are indicated by reference numeral 210.
[0062] The functional modules may include a liquid crystal display
207a, a receiver (or speaker) 207b made of piezoelectric material,
a thinned microphone 207c, a CCD camera 207d, a button 207e such as
a touch panel, a light emitter 207f such as an LED, a thinned
antenna 207g for receiving a signal, a thinned battery 207h and a
thinned vibrator 207i for generating vibrations.
[0063] In FIG. 6, the functional modules 207a-207i are positioned
on the organic films 201 and 203 made of PET or polyimide and
having a thickness of about 100 .mu.m. Also, the organic film 201
supports modules having an audio-visual interface for operators, on
top of which the protective film 204 is bonded. The components
mounted on the organic film 201 transform electrical and optical
signals into corresponding audio signals and vice versa. Also,
circuits connected between various functional modules process
necessary information.
[0064] The organic film 203 supports various functional modules for
supplying power to mobile terminals, receiving signals and
generating vibrations, irrelevant to audio-visual operation of
human beings. A bottom surface of the organic film 203 is covered
by the protective film 206.
[0065] As shown in FIG. 7, in order to process and control signals
to and from the functional modules 207a-207i, the organic films are
electrically connected by metal connections 210 such as metal
bumps. Other portions, except metal connections 210, are
electrically disconnected from each other. Also, in order to
connect the organic films, an organic material such as bonding film
205 is provided therebetween.
[0066] Each of the organic films 201, 202 and 203 may be made of a
plurality of stacked films. In this instance, the bonding film 205
may be placed between the stacked films.
[0067] For an optical connection between layers, a transparent film
may be provided entirely or partially between the layers so that
light emitted from a light emitter such as an LED is received by a
light receiver such as a photo-diode.
[0068] The organic film 202 supports various functional circuits
such as a functional component or device for processing and
controlling various signals. The functional circuits include a
thinned capacitor 208a, a thinned register 208b and thinned
inductor 208c. These functional circuits may be manufactured on the
organic film 202 by a suitable film formation technique such as
sputtering. Alternatively, these thinned functional components may
be prepared on another organic film, which are then separated from
each other.
[0069] The functional circuits are manufactured by forming one or
more layers, each having a thickness of less than 10 .mu.m, by use
of a known film formation technique and then patterning the layers.
If this manufacturing requires a film formation process in which a
circuit is exposed to an elevated temperature, a heat resisting
material such as polyimide is preferably used for the organic film
202. The functional devices 209 may be bare chips including
semiconductors made of silicon and/or other chemical compounds. For
example, the devices 209 are an IC and an LSI capable of
electrically performing a calculation, or semiconductor devices
made of GaAs and/or other chemical compounds and capable of
functioning as optical circuits. These bare chips, functional
devices 209, are mounted on wires formed on the organic film 202
through metal connections such as bumps. For example, each device
209 has a thickness equal to or less than about 100 .mu.m.
[0070] Using the circuits described above, constructed is a thinned
mobile terminal device, i.e., a circuit structure shown in FIG. 7.
As described above, since multi-layered bases are made of thin and
light film, the structure has a minimum thickness, equal to or less
than about 7 .mu.m, for example, and a minimum weight.
[0071] Although the structure of the film-like integrated circuit
is applied to a mobile device (i.e., thinned cellular phone), it
can be embodied as other thinned devices because of its minimum
thickness of about equal to or less than 7 .mu.m. As shown in FIGS.
8A to 8F, examples of thinned devices are a sheet-like computer
241, an identification such as an ID card 242, an electronic wallet
243, a personal data assistant (PDA) 244, a remote controller 245
and a memory card 246 for use with an electrical device such as
electric washer 247, television 248 and microwave oven 249.
[0072] Functions provided by this structure are not limited to
those for mobile devices, but may be those required for a sheet
type computer, sheet ID such as a passport, license and name card,
sheet memory for recording audio and visual data, sheet wallet such
as credit card and season ticket and sheet-like remote
controller.
[0073] As described above, according to the film-like integrated
circuit structure, since the electronic components and functional
circuits are electrically connected through three dimensionally
arranged electric wires, i.e., connections defined in layers and
wires formed on the layers, a length of the wires running between
the functional components and modules can be minimized.
[0074] Also, a conventional flexible board for providing connection
between a multi-layered circuit board can be eliminated.
Additionally, the film base is light as compared with a
conventional multi-layered circuit board made of epoxy with glass
fibers. Thus, the circuit board is light in weight.
[0075] Further, a metal connection such as bumps can be used for
connection between layers and between bare-chip devices and
associated circuits, which reduces a deterioration of
high-frequency signals to a certain extent when compared with a
conventional connection using conductive paste material, and
thereby decreases a signal transmission loss.
[0076] Furthermore, since the multi-layered device employs an
optical connection for signal transmission between layers, an
optical signal from an optical device can be used as optical
information, which considerably reduces an adverse affect caused by
noises and allows a high speed and mass signal processing.
[0077] Moreover, functional circuits and bare-chip functional
devices made of thin films, each having a thickness less than 10
.mu.m, are incorporated between the layers. Then, when compared to
a circuit structure using chip components or package devices, a
possible inaccuracy due to mounting of those devices is eliminated,
which improves performance of an overall circuit.
[0078] Therefore, the present invention provides a compact
multi-layer circuit device in which operational signal frequency
can further be increased and a signal can be transmitted at a high
speed.
Sixth Embodiment
[0079] FIG. 10A also shows a thinned multi-layer circuit device
according to a sixth embodiment of the present invention. As shown
in the drawing, thinned multi-layer circuit 311 has a plurality of
circuit modules 312, i.e., layers, superposed with one another.
Each circuit module 312 has first and second rectangular circuit
boards, 313 and 314, and a strip-like connecting portion 315
connecting the first and second circuit boards. A base layer 316
defining the circuit module 312 is made from a flexible thin sheet
made of insulative material. For example, the sheet is made from a
flexible resin film or a metal film coated with an insulative
material. The sheet is cut and configured so that it outlines both
the first and second circuit boards 313 and 314 and the connecting
portion 315. The circuit boards 313 and 314 support necessary
electronic and/optical components 317 such as resistors,
capacitors, coils and LSIs. As required, the components 317 are
electrically connected to each other through wires 318 made of
metal film and defined on one or opposite surfaces of the circuit
boards 313 and 314. The connecting portion 315, on the other hand,
supports connecting wires 319 for electrically and optically
connecting the components 317 and wires 318 on the first and second
circuit boards 313 and 314, as required. Other electrical and/or
optical connections including through-holes (not shown) are formed
in the circuit boards 313 and 314 and the connecting portion 315
for connecting wires 318 in one layer and wires 318 in other
layers.
[0080] In this embodiment, base layers 316 of the circuit modules
312 have the same configuration so that, once the modules 312 are
superposed, the first and second circuit boards 313 and 314 and the
connecting portion 315 of one circuit module 312 are correctly
aligned on those of an adjacent circuit module 312. The electronic
components 317 and wires 318 and 319 on one circuit module 312 need
not be identical to those on other circuit modules. Typically, each
circuit module 312 bears components and wires different from those
of other modules.
[0081] As shown in FIG. 10B, the circuit modules 312 so formed are
superposed so that the first and second circuit boards 313 and 314
and the connection portion 315 of one circuit module 312 are
positioned on those of other circuit modules 312. Also, the
superposed circuit connections 315 are then pressed and integrated,
which results in the thinned multi-layer circuit 311. If necessary,
a suitable adhesive is used for bonding at least respective parts
of the superposed circuit boards and/or connecting portions.
Preferably, a bonded area of each circuit board is equal to or less
than 50% of a total area of the circuit board for effective heat
radiation from an interference between the superposed circuit
boards, and also for retaining a good flexibility of the
multi-layer circuit.
[0082] The electric wires 318 and 319 of each circuit module 312
are electrically connected with associated wires of other circuit
modules through electrical connections or through holes defined in
the circuit boards 313 and 314 and/or the connecting portions 315.
This means that the superposed circuit boards 313 and 314 are
electrically connected only through such connections, thereby
allowing heat generated in the circuit boards 313 and 314 of the
circuit modules 312 to be discharged into an atmosphere through
possible small gaps between unconnected portions of the circuit
boards.
[0083] As described above, the integrated thinned multi-layer
circuit 311 still has significant flexibility so that it can be
bent or curved easily, thereby allowing the circuit to be
accommodated within a housing with any configuration having convex
and/or concave portions.
Seventh Embodiment
[0084] FIG. 11A shows another thinned multi-layer circuit device
311A according to a seventh embodiment of the present invention. As
shown in the drawing, the multi-layer circuit device 311A of this
embodiment is different from that of sixth embodiment in that
connecting portion 315 of one circuit module 312 takes a specific
position relative to its circuit boards 313 and 314, so that, when
circuit modules 312 are superposed, the connecting portion 315 of
the one module takes a different position from those of other
modules.
[0085] Therefore, as can be understood when comparing the
multi-layer circuits shown in FIGS. 11A and 10A, although the
connecting portions 315 of the multi-layer circuit 311A occupies a
larger area than that of the previous embodiment, a thickness of
the connecting portions in the multi-layer circuit is far smaller
than that of the previous embodiment. For example, if the
connecting portions are arranged so that they have no overlap with
each other, the thickness of the connecting portions in the
multi-layer circuit board corresponds substantially to that of a
single connecting portion. This results in significant flexibility
of the multi-layer circuit board, thereby allowing the circuit
board to be designed more freely.
Eighth Embodiment
[0086] FIG. 12 shows a thinned multi-layer circuit board 311B
according to an eighth embodiment of the present invention.
Although the multi-layered circuit board 311B has a plurality of
circuit modules 312 layered one on top of another like the seventh
embodiment, it is different from that embodiment in a layering
order of the circuit boards. Specifically, on the left part of the
multi-layered circuit, indicated on the left side of FIG. 12,
positioned in a top layer is a circuit board 313a of one circuit
module 312, and in a second layer is a circuit board 313b. On the
other hand, on the right part of the multi-layer circuit board,
indicated on the right side of FIG. 12, circuit board 314a is
positioned in the second layer and circuit board 314b is in the top
layer. That is, a layering order of the circuit boards is different
on the left and right sides. For clarity, only one example is shown
in the drawing in which the top two layers of the circuit boards
313 and 314 are exchanged; however, a layering order of the circuit
boards can be modified freely.
* * * * *