Patent Application
20130266758
The present invention relates to a method of manufacturing a laminated electronic part and such a laminated electronic part, and more particularly, to an electronic part which includes a plurality of ceramic laminates that differ in the direction in which internal conductive layers are laminated.
Laminated electronic parts have been provided for implementing a variety of circuit functions. The laminated electronic part comprises circuit elements such as circuit components, connection conductors, and the like disposed on a plurality of wiring layers of a laminate in a distributed manner.
Meanwhile, as electronic devices are increasingly reduced in size and profile and provided with more and more functions, electronic parts which comprise the devices are highly required to be reduced in size and height (thickness), as well as to be increased in functionality and integration. For example, a filter for a laminated ceramic electronic part is one of main components of portable phones and wireless LAN devices. This filter employs a ceramic laminate which is constructed by forming electrodes on thin dielectric materials (laminate), and placing them one on another to form an inductor and a capacitor. Such a ceramic laminate is advantageous in providing for smaller size and lower profile. In addition, the ceramic laminate exhibits good characteristics in heat-resistivity, thermal expansion, thermal conductivity, resistance to chemical attack, and the like, as compared with resin-based glass epoxy laminates and the like, and is also utilized particularly for wiring of electronic parts to which higher integration is required. In this way, electronic parts including ceramic laminates are widely utilized in high-frequency electronic parts which are required to provide a variety of high functionality. However, as an electronic part is reduced in size, circuit elements (circuit components, connection conductors, and the like) disposed therein are necessarily brought in closer proximity, resulting in higher susceptibility to deteriorations in characteristics of the electronic part due to stray capacitance and undesired electromagnetic coupling. For this reason, several structures have been proposed for electronic parts to prevent mutual interference of circuit elements to one another, such as constructing an electronic part with a plurality of laminates which are laminated in different directions, and the like (see, for example, Patent Documents 1-4 below).
Notably, although the structures described in the patent documents listed above are applied with a design idea for changing the direction in which conductors are laminated within a part, respective laminates which comprise the electronic part are individually sintered and adhered such that they are laminated in different directions to fabricate individual electronic parts (see Paragraphs 0038-0039 of Patent Document 2 and Patent Document 3). Therefore, the structures described in these documents require more efforts in manufacturing and is inferior in mass productivity.
Assuming, for example, that chip filters are manufactured, individual chips are sized to have the width, depth, and height dimensions of, for example, approximately 1 mm, 0.5 mm, and 0.35 mm, respectively, so that it is envisaged that difficulties will be actually involved in adhering laminates, which have even smaller dimensions, to each other to fabricate the chips. This is because it is not that laminates may be simply adhered to one another, but conductors included in adjacent laminates must be electrically connected to each other, thus requiring precise positioning and fixing in the adhesion. Moreover, as a smaller target (chip size) causes positioning errors to become relatively larger and highly accurate positioning to be exceptionally more difficult, it is not easy to individually perform the positioning of laminates one by one and adhere the laminates. Thus, the structures described in the aforementioned documents cannot be said to be a pragmatic structure suitable for mass production.
Also, the sintering of individual laminates not only involves complicated treatments but also causes a lower stability in shape, as compared with the laminates which are placed in groups. Particularly, small-sized individual laminates can suffer from deformations when they are sintered, and such deformations can cause misalignments between internal electrodes of the laminates when they are bonded to each other. As such, with the conventional structures of the parts, it is difficult to manufacture a laminated electronic part including a plurality of ceramic laminates which are laminated in different directions satisfactorily with respect to the yield rate and productivity.
It is therefore an object of the present invention to provide a new part structure which is more apt to exhibit satisfactory electric characteristics, even if it is reduced in size, for a laminate electronic part which includes a plurality of ceramic laminates which are laminated in different directions. More particularly, it is an object of the present invention to efficiently manufacture such a laminated electronic part.
To solve the foregoing problem and achieve the object, a method of manufacturing a laminated electronic part according to the present invention includes the steps of (1) fabricating a first laminated sheet by laminating one or more insulating function layers mainly made of an unsintered ceramic material and one ore more conductor layers, each having a plurality of conductors two-dimensionally arranged in a vertical direction and in a horizontal direction, where the conductors make up at least part of circuit components; (2) fabricating a second laminated sheet by laminating one or more insulating function layers mainly made of an unsintered ceramic material and one ore more conductor layers, each of which has a plurality of conductors two-dimensionally arranged in a vertical direction and in a horizontal direction, where the conductors make up at least part of circuit components; (3) cutting the first laminated sheet into sticks such that the sticks include a plurality of conductors arranged either in the vertical direction or in the horizontal direction, thereby creating a plurality of first laminate sticks; (4) cutting the second laminated sheet into sticks such that the sticks include a plurality of conductors arranged either in the vertical direction or in the horizontal direction, thereby creating a plurality of second laminate sticks; (5) fabricating a third laminated sheet by rotating the second laminate sticks by 90° about a longitudinal axis of the second laminate stick, arranging the rotated second laminate sticks to be each sandwiched between the first laminate sticks, and thermocompression bonding the first laminate sticks and second laminate sticks for integration; (6) singulating the third laminated sheet into chips by cutting the third laminated sheet in the vertical direction and in the horizontal direction such that each chip includes a first laminate which is part of the first laminate stick and a second laminate which is part of the second laminate stick; and (7) creating sintered bodies by sintering the unsintered chips to integrate the first laminate with the second laminate.
The method of manufacturing a laminated electronic part according to the present invention is directed to a method of manufacturing an electronic part which has a structure made up of two or more bonded ceramic laminates which are laminated in different directions. However, rather than bonding individual laminates after sintering, as proposed in the past, the present invention involves bonding together those laminates, each of which is a stick-shaped grouping (including a plurality of the same laminates) such as laminate sticks (first laminate sticks and second laminate sticks), through thermocompression bonding (with application of heat and pressure) to fabricate the third laminated sheet which is made up of the bonded laminates which are laminated in different directions, where the third laminated sheet constitutes a grouping (a grouping of a plurality of sets of the laminates which are laminated in different directions) of these laminates (first laminate and second laminate). In this regard, the third laminated sheet is fabricated at temperatures lower than sintering temperatures (for example, 700-1600° C.) at which the sintering is performed after the first laminate sticks are bonded to the second laminate sticks. Specific heating temperatures for fabricating the third laminated sheet depend on the materials of the insulating function layer and conductor and therefore cannot be defined in general, but may be set, for example, in a range of approximately 30 to 200° C.
As described above, the present invention eliminates the need to handle individual laminates when bonding a plurality of laminates (first laminate, second laminate) which make up an electronic part, and can collectively bond the laminates in groups, thus demonstrating high operability and good productivity. Additionally, since the sintering is performed after the laminates are bonded, it is possible to suppress errors in shape which can be caused by the sintering.
The “insulating function layer” described above, typically refers to an insulating layer formed of a dielectric ceramic material, but is not so limited and may be a material layer formed of any of a variety of insulating ceramic materials such as a magnetic ceramic material, a semiconductor ceramic material, and the like, for example, in conformity to elements which are to be included within a laminated board. Additionally, a single laminate can be formed of a mixture of different insulating function layers.
Also, in the present invention, the laminates which make up an electronic part are not limited to two (only the first laminate and second laminate). For example, the electronic part may be made up of three laminates, or can have a structure made up of four more bonded laminates. When three or more laminates are included in this way, a third laminate stick, or further (fourth, fifth, . . . ) laminate sticks may be formed in a similar manner, in addition to the first laminate stick and second laminate stick, and they may be combined as appropriate to fabricate the third laminated sheet.
Further, in the present invention, all the laminates included in an electronic part need not be always laminated in different directions. For example, in an electronic part which has a first laminate, a second laminate, and a third laminate bonded in this order in a line, the electronic part may include a plurality of laminates which are laminated in the same direction, such as the first laminate and third laminate which are laminated in the same direction (for example, in the horizontal direction or in the vertical direction), the second laminate which is laminated in a different direction from them (for example, in the vertical direction or in the horizontal direction), and the like. Also, a method of fabricating the first laminated sheet and second laminated sheet, though not particularly specified, may include, in one example, fabricating a plurality of first ceramic sheets by printing conductors which form at least part of circuit components on a surface of a ceramic green sheet mainly made of an unsintered ceramic material such that the conductors are two-dimensionally arranged in the vertical direction and in the horizontal direction; and creating the first laminated sheet by putting the plurality of first ceramic sheets one on another, and thermocompression bonding the plurality of first ceramic sheets into integration. Similarly, the fabricating the second laminated sheet may include fabricating a plurality of second ceramic sheets by printing conductors which form at least part of circuit components on a surface of a ceramic green sheet mainly made of an unsintered ceramic material such that the conductors are two-dimensionally arranged in the vertical direction and in the horizontal direction; and creating the second laminated sheet by putting the plurality of second ceramic sheets one on another, and thermocompression bonding the plurality of second ceramic sheets into integration.
In this regard, the method of fabricating the laminated sheets (first laminated sheet and second laminated sheet) in the present invention can be also implemented, other than the method described above, by other methods such as, for example, by alternately printing and laminating a conductive paste for forming a conductor and an insulating paste for forming an insulating function layer.
On the other hand, a laminated electronic part according to the present invention comprises a first laminate including one or more insulating function layers mainly made of a ceramic material laminated with one or more conductor layers; and a second laminate including one or more insulating function layers mainly made of a ceramic material laminated with one or more conductor layers, and bonded with the first laminate, wherein the first laminate is laminated in a direction which intersects with a direction in which the second laminate is laminated, and the first laminate and the second laminate make up a sintered body which is integrated by sintering.
Also, the first laminate may be laminated in a direction substantially orthogonal to the direction in which the second laminate is laminated.
With the provision of such a part structure including a plurality of laminates which are laminated in different directions, it is possible to prevent mutual interference between circuit elements included in the electronic part, such as preventing electromagnetic coupling between a first laminate and a second laminate, for example, when an inductor is disposed in each of them, reducing a parasitic capacitance which can occur between circuit elements disposed in the first laminate and second laminate, respectively, and the like, to accomplish satisfactory electric characteristics.
Also, in one aspect of the laminated electronic part according to the present invention, the insulating function layer of the first laminate and the insulating function layer of the second laminate are made of the same material, wherein the insulating function layer of the first laminate and the insulating function layer of the second laminate are continuously sintered across a bonding surface therebetween.
Further, in another aspect of the laminated electronic part according to the present invention, the insulating function layer of the first laminate and the insulating function layer of the second laminate are made of different materials, wherein an interface exists on a bonding surface between the insulating function layer of the first laminate and the insulating function layer of the second laminate.
Further, in a yet another aspect of the laminated electronic part according to the present invention, a diffusion layer is formed on a bonding surface between the insulating function layer of the first laminate and the insulating function layer of the second laminate, where the diffusion layer includes either one or both of a material which constitutes the insulating function layer of the first laminate and a material which constitutes the insulating function layer of the second laminate.
According to a part structure formed with such a diffusion layer, the first laminate can be more firmly coupled to the second laminate, and a difference in thermal expansion between the first laminate and the second laminate is alleviated by the diffusion layer, thus making it possible to prevent troubles from occurring due to changes in temperature in subsequent manufacturing steps or after the part has been incorporated in a variety of products, such as cracking and peeling between the first laminate and the second laminate, damages on electric connections between the two laminates, and the like.
In the present invention, insulating function layers of different materials may be mixed in a single laminate, as described above. Specifically, either one or both of the first laminate and second laminate may have insulating function layers made of two or more different materials, in which case, the interface or diffusion layer may exist on part of the bonding surface between the first laminate and the second laminate.
Also, in a yet further aspect of the laminated electronic part according to the present invention, a third material other than those materials included in the first laminate and second material, for example, an adhesive material (for example, a material capable of providing an adhesive action by applying heat thereto) is not interposed between the first laminate and the second laminate, so that the first laminate is directly bonded to second laminate.
Also, in a yet further aspect of the laminated electronic part according to the present invention, the first laminate is bonded to the second laminate to create a bonding surface, wherein one or more of conductors included in the first laminate have their ends in abutment to surfaces of one or more of conductors included in the second laminate on the bonding surface, causing the conductor included in the first laminate to be electrically connected to the conductors included in the second laminate.
With the provision of such a conductor connection structure, a variety of circuit elements included in one laminate can be electrically connected to a variety of circuit elements included in another laminate without intervention of connection conductors such as vias, connection lines for connection, and the like, such as, for example, by directly connecting a circuit component (for example, an inductor) included in one laminate to be bonded to a circuit component (for example, a capacitor) included in another laminate, or directly connecting a ground electrode included in one laminate to a circuit component included in another laminate, and the like, thus making it possible to prevent deteriorations in electric characteristics due to the intervention of connection conductors.
The “laminated electronic part” in the present invention typically refers to a composite electronic part including a plurality of circuit components. While a “circuit component” may include, for example, a passive component such as an inductor, capacitor, resistor, varistor, and the like, the laminated electronic part may additionally include a variety of circuit elements, for example, an active component such as a transistor, and FET, an integrated circuit including active components such as IC, connection conductors such as a conductor line and inter-layer connection conductor (via, throughhole, and the like), ground electrode, terminal electrode, and the like (the same goes for the manufacturing method of the present invention as well).
Further, when the laminated electronic part, as referred to in the present invention, is considered from a functional point of view (type of part), the laminated electronic part as referred to in the present invention includes a variety of electronic parts, for example, filters such as bandpass filter, low pass filter and high pass filter, and the like, duplexer, diplexer, power amplifier module, high-frequency multiplexer module, isolator, sensor, and the like.
According to the method of manufacturing a laminated electronic part, and the laminated electronic part, it is possible to efficiently manufacture a laminated electronic part which includes a plurality of ceramic laminates which are laminated in different directions.
Other objects, features, and advantages of the present invention will be made apparent from the following description of embodiments of the present invention, made with reference to the drawings. It should be apparent to those skilled in the art that the present invention is not limited to the following embodiments, but a variety of modifications can be made within the scope of the invention defined by the appended claims. In the drawings, the same reference numerals indicate the same or corresponding parts.
Referring to
Also, as shown in
As shown in
In this event, the first ceramic sheets 11a-11g are formed with inter-layer connection conductors such as via holes, if required, in addition to the conductor patterns 12 corresponding to circuit elements which should be disposed on respective wiring layers of the first laminates, as described above (they are formed similarly on second ceramic sheets 21a-21d described later with reference to
Next, the ceramic sheets 11a-11g are laid one on another in a predetermined order, while aligned, as shown in
A second laminate stick is fabricated in a similar manner. As shown in
Next, the second ceramic sheets 21a-21d are laid one on another in a predetermined order, while aligned, as shown in
Then, as shown in
As shown in
Subsequently, the individual chips are sintered. In this way, the first laminates (left first laminate 51 and right first laminate 52) and second laminate 53 are sintered to cause the interface between both laminates 51-53 to disappear, as shown in
As appreciated,
Specifically, as shown in
Likewise, when the second laminate 53 employs second ceramic layers 82 to be in contact with the first laminates 51, 52 as shown in
Further,
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP11/066560 | 7/21/2011 | WO | 00 | 1/18/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 20130115411 A1 | May 2013 | US |
