JP2005235808A - Stacked electronic component and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stacked electronic component in which adhesive strength of an external terminal electrode and a resin layer is raised and the external terminal electrode is prevented from being peeled from the resin layer against a shock from outside, and to provide a manufacturing method of the component. <P>SOLUTION: The stacked electronic component is provided with a ceramic multilayer substrate 1, resin layers 10 (11 and 12) fixed to the lower face of the ceramic multilayer substrate, and external terminal electrodes 13 exposed from the lower face of the resin layer 10. The lower face of the resin layer 10 is formed to be flat and the lower faces of the external terminal electrodes 13 are located upper than the lower face of the resin layer 10. Center parts of the external terminal electrodes 13 are exposed from the resin layer 10 and almost whole peripheries of the external terminal electrodes 13 are covered with the resin layer 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a multilayer electronic component formed by laminating a ceramic substrate and a resin layer and a method for manufacturing the same.

With rapid progress of miniaturization and high functionality of wireless communication devices such as mobile phones, mounted components are required to realize high functions in a smaller space. In order to meet such a demand, a multilayer electronic component having a ceramic multilayer substrate has been used.
In such a multilayer electronic component, in order to realize further miniaturization and higher functionality, an electronic component is connected not only to the upper surface but also to the lower surface of the ceramic multilayer substrate.

Patent Document 1 proposes a composite ceramic component in which a resin layer is provided on the mounting surface side (lower surface side) of a ceramic multilayer substrate. Circuit elements such as semiconductor elements and passive components are connected to the lower surface of the ceramic multilayer substrate, and these elements are embedded in the resin layer. The lower surface of the resin layer is formed flat, and an external terminal electrode is formed here. The external terminal electrode is electrically connected to the ceramic multilayer substrate through a via-hole conductor formed in the resin layer in the thickness direction.

A via-hole conductor is formed by filling a via-hole provided in a semi-cured resin layer with a conductive paste, press-bonding the resin layer to a ceramic multilayer substrate, and then thermally curing the resin layer at the same time. The In general, the thermal expansion coefficient of the via-hole conductor is 16 to 20 ppm / ° C., whereas the resin layer around the via hole conductor is added with an inorganic filler or the like, so that the thermal expansion coefficient is as small as 11 to 16 ppm / ° C. This difference causes a difference in expansion due to heat such as reflow. Therefore, the via-hole conductor is raised from the lower surface of the resin layer, and a force in the direction of peeling off the external terminal electrode acts. As a result, the external terminal electrode is joined only by the via-hole conductor. Since the via-hole conductor has a small amount of resin component used for bonding in order to ensure conductivity, the bonding force is weak. For this reason, even if a slight impact is applied from the outside, this joining may come off and there is a risk of causing poor conduction.
Further, the external terminal electrode is pulled across the entire surface of the external terminal electrode via solder when a force that peels off the printed circuit board and the composite ceramic component is applied by an external impact such as dropping. For this reason, the external terminal electrode and the resin layer are peeled off starting from the outer peripheral portion of the external terminal electrode, which may cause poor conduction.

Patent Document 2 proposes a circuit board device that includes a conductor pad provided on the surface of a substrate and an overcoat layer that covers the outer periphery of the conductor pad. The center portion of the conductor pad is exposed from the overcoat layer, the exposed surface of the conductor pad and the surface of the overcoat layer are on the same plane, and a part of the conductor pad is embedded in the substrate. .
In this case, since the outer peripheral portion of the conductor pad is covered with the overcoat layer, peeling of the conductor pad can be prevented when mounting an electronic component on the conductor pad or mounting the circuit board device on the motherboard. . In addition, since the exposed surface of the conductor pad and the surface of the overcoat layer are on the same plane, there is an advantage that mounting can be ensured. In addition, since there is no step between the conductor pad and the overcoat layer, there is an advantage that there is no unevenness on the substrate surface, and flux residue and the like are less likely to remain.

In order to realize the circuit board device having the above-described structure, first, an overcoat layer is formed on a support, a through hole is formed in the overcoat layer, a conductive paste is applied thereon, and a top surface thereof is formed thereon. A method of forming a circuit board material is used. However, when the circuit board material is a ceramic material, a resin layer cannot be used as the overcoat layer. This is because the resin layer is burned off when the ceramic material is fired. For this reason, it is difficult to realize this structure in a multilayer electronic component having a resin layer on a ceramic substrate.
Further, when the overcoat layer is formed of a ceramic material, the thickness of the overcoat layer is thin. Therefore, the overcoat layer is easily cracked due to a difference in shrinkage from the electrode due to firing, and it is difficult to stably secure the bonding strength of the electrode.
Furthermore, in the case of an external terminal electrode whose surface is plated, moisture may be trapped in the electrode. In this case, the moisture trapped at the time of reflow for mounting the multilayer electronic component on the motherboard is vaporized and expanded, and the vaporized moisture that has lost its escape is released to the outside through the molten solder. At this time, molten solder may be scattered around.
JP 2003-124435 A JP 2002-198637 A

Therefore, an object of the present invention is to improve the adhesive strength between the external terminal electrode and the resin layer when the external terminal electrode is provided on the resin layer fixed to the lower surface of the ceramic substrate, so that the external terminal electrode against an external impact An object of the present invention is to provide a multilayer electronic component and a method for manufacturing the same, which can prevent the resin from peeling from the resin layer.

In order to achieve the object, the invention according to claim 1 is characterized in that a ceramic substrate on which a conductor pattern is formed, a resin layer fixed to the lower surface of the ceramic substrate, and exposed from the lower surface of the resin layer, An external terminal electrode connected to the conductor pattern of the ceramic substrate through a via-hole conductor provided in the layer, wherein the lower surface of the resin layer is formed flat, and the external terminal electrode The lower surface is located above the lower surface of the resin layer, the central portion of the external terminal electrode is exposed from the resin layer, and the outer peripheral portion of the external terminal electrode is covered with the resin layer. Provide multilayer electronic components.

According to a fourth aspect of the present invention, there is provided a ceramic substrate on which a conductor pattern is formed, a resin layer fixed to the lower surface of the ceramic substrate, and a via hole exposed from the lower surface of the resin layer and provided in the resin layer. In a multilayer electronic component comprising an external terminal electrode connected to the conductor pattern of the ceramic substrate via a conductor, the lower surface of the resin layer is formed flat, and the lower surface of the central portion of the external terminal electrode and the resin layer Are formed on the same plane, the lower surface of the outer peripheral portion of the external terminal electrode is positioned above the lower surface of the central portion, the central portion of the external terminal electrode is exposed from the resin layer, and the external terminal electrode The multilayer electronic component is characterized in that the outer peripheral portion of the substrate is covered with the resin layer.

The invention according to claim 1 will be described.
In the case of a multilayer electronic component in which a resin layer is provided on the lower surface of a ceramic substrate, the resin layer serves as a shock absorbing layer for the ceramic substrate such as a drop impact. The external terminal electrode exposed on the lower surface of the resin layer is electrically connected to the conductor pattern of the ceramic substrate via the via hole conductor.
The outer periphery of the external terminal electrode is covered with a resin layer. In other words, in addition to the bonding force between the external terminal electrode and the resin layer, the resin physically presses the periphery of the external terminal electrode, and the pressing position is on the outer peripheral portion from which the peeling starts. The terminal electrode is difficult to peel off. Therefore, even if a force in the peeling direction acts on the external terminal electrode due to thermal expansion or a drop impact of the via-hole conductor, peeling can be reliably prevented. Since the resin surrounds the external terminal electrode, the solder does not spread more than necessary, and the peeling force collects in the vicinity of the central portion, making it more difficult to peel off.
Since the lower surface of the resin layer is flat, when mounted on a mother board or the like, it can be stably mounted, and flux residues and the like are not easily accumulated.
In the present invention, since the material framing the outer peripheral portion of the external terminal electrode is a resin, even if the thickness of the framing layer is thin, there is no difference in shrinkage from the electrode because it is not fired. Can be prevented.
Note that it is not necessary that the entire outer periphery of the external terminal electrode is embedded in the resin layer. If the external terminal electrode does not peel off due to thermal expansion or a drop impact of the via-hole conductor, a part of the outer peripheral electrode May be exposed from the resin portion.

The lower surface of the external terminal electrode is located above the lower surface of the resin layer. That is, the external terminal electrode is exposed at a position deeper than the lower surface of the resin layer. Therefore, when moisture is trapped in the electrode, even if the moisture trapped during reflow vaporizes and expands and is released to the outside through the molten solder, it surrounds the external terminal electrode. The wall surface of the resin layer can prevent the solder from scattering.
When the difference in height between the lower surface of the external terminal electrode and the lower surface of the resin layer is set to 5 to 100 μm as in claim 2, it is possible to more reliably prevent solder from scattering.

According to a third aspect of the present invention, the resin layer includes a first resin layer fixed to the lower surface of the ceramic substrate and a second resin layer fixed to the lower surface of the first resin layer. An external terminal electrode is formed at the interface between the resin layer and the second resin layer, and the second resin layer is provided with an exposed hole that exposes the central portion of the external terminal electrode and covers almost the entire circumference of the outer peripheral portion. It is good to have a configuration.
In this case, the outer peripheral part of an external terminal electrode can be easily covered by making a resin layer into a 2 layer structure and making an outer layer (2nd resin layer) into a framing layer.
In this case, if the first resin layer and the second resin layer are formed of the same material, the adhesion strength between them is high and the thermal expansion coefficient is the same, so that problems such as peeling can be solved.

In claim 4, unlike in claim 1, the lower surface of the central portion of the external terminal electrode and the lower surface of the resin layer are formed on the same plane, and the lower surface of the outer peripheral portion of the external terminal electrode is positioned above the lower surface of the central portion. It is configured.
In this case, since one resin layer also serves as the framing layer of the external terminal electrode, the structure is simplified. In addition to the bonding force between the external terminal electrode and the resin layer, since the resin physically presses the periphery of the external terminal electrode, the external terminal electrode is difficult to peel off.
Since the lower surface of the central portion of the external terminal electrode and the lower surface of the resin layer are formed on the same plane, the external terminal electrode can be reliably mounted on a mother board or the like, and the stability of the electronic component is improved. In addition, since there is no unevenness on the lower surface of the electronic component, flux residues and the like during mounting are less likely to remain.

According to a fifth aspect of the present invention, the external terminal electrode is made of a Cu foil having a Ni—Au plating surface.
Ni—Au plating can improve solderability and prevent solder erosion.
When Ni-Au plating is applied to the electrode, the hydrogen ions generated from the reducing agent in the plating bath during Ni plating are dissolved in Ni, and the crystal lattice is expanded and cured, and then diffused and released. Tensile stress remains in the layer. Thereby, the copper foil which forms the external terminal electrode of a resin layer peels off and may cause a conduction defect.
On the other hand, since the outer peripheral portion of the external terminal electrode is covered with the resin layer as in the present invention, the peeling of the copper foil can be prevented even if a tensile stress remains in the plating layer.

According to a sixth aspect of the present invention, the ceramic substrate may be a low-temperature fired ceramic multilayer substrate in which a plurality of ceramic layers are laminated, and a conductor pattern mainly composed of Ag or Cu may be formed therein.
In recent years, low-temperature fired ceramic materials (LTCC) have become the mainstream material for ceramic multilayer substrates. This is because LTCC can be sintered at a temperature of 1000 ° C. or less and can be co-sintered with a low-resistance metal such as Ag or Cu. Examples of LTCC materials include glass composite LTCC materials obtained by mixing borosilicate glass with ceramic powder such as alumina and forsterite, and crystals using ZnO—MgO—Al ₂ O ₃ —SiO ₂ crystallized glass. Non-glass-type LTCC materials using a glass-based LTCC material, BaO—Al ₂ O ₃ —SiO ₂ ceramic powder, Al ₂ O ₃ —CaO—SiO ₂ —MgO—B ₂ O ₃ ceramic powder, etc. . A low melting point metal such as Ag or Cu has a lower resistance than a high melting point metal such as tungsten, and is particularly suitable for forming a conductor pattern for high frequency applications.
However, LTCC is more fragile than pure ceramic because it contains a considerable amount of glass or the like to lower the firing temperature. For example, the bending strength of pure alumina is 300 MPa, whereas the bending strength of a glass ceramic having a volume ratio of alumina and glass of 50:50 is about 200 MPa. For this reason, when a drop test is performed in a state where the ceramic multilayer substrate is mounted on the mother board, a tensile stress is generated at a joint portion between the ceramic multilayer substrate and the mother board, and the ceramic multilayer substrate is likely to be cracked.
If the present invention is applied to such a multilayer electronic component using LTCC, it is preferable because the resin layer functions as a shock absorbing layer of the ceramic multilayer substrate.

According to a seventh aspect of the present invention, a circuit element connected to the lower surface of the ceramic substrate and embedded in the resin layer may be provided.
By connecting the circuit element to the ceramic substrate and embedding the circuit element in the resin layer, further miniaturization and higher functionality can be realized. The resin layer has a role as a protective layer for the circuit element and a role as a shock absorbing layer for the ceramic substrate.
As the circuit element, an active element such as a semiconductor device, a chip-type diode, and a chip-type transistor, a passive element such as a chip-type capacitor, a chip-type inductor, a chip-type resistor, and a chip-type filter can be used. The connection method may be one in which the element is fixed to the ceramic substrate and then electrically connected by wire bonding, one in which flip chip mounting is performed via a bump electrode, or the other in surface mounting.

As in claim 8, the support is pressure-bonded with the first resin sheet interposed between the lower surface of the ceramic substrate, the external terminal electrode is fixed to the lower surface of the first resin sheet, and the external terminal electrode is connected to the via-hole conductor. The first resin sheet is thermally cured, and then the support is peeled off from the first resin sheet, the external terminal electrodes are transferred to the first resin sheet, A laminated type using a method in which the second resin sheet is pressure-bonded to the lower surface of the first resin sheet so that the outer periphery of the terminal electrode is covered with the inner periphery of the exposed hole, and the second resin sheet is thermally cured. Electronic components can be manufactured.
In this case, the multilayer electronic component according to claim 1 can be easily obtained by sequentially laminating the first resin layer and the second resin layer.
Moreover, the external terminal electrode can be easily fixed to the first resin sheet by transferring the external terminal electrode from the support to the first resin sheet.
As a method for attaching the external terminal electrode to the support, for example, a metal foil may be attached by metal plating, or an adhesive may be attached.

As in claim 9, a support is pressure-bonded with a resin sheet interposed between the lower surface of the ceramic substrate, the external terminal electrode is fixed to the lower surface of the resin sheet, and the external terminal electrode is connected to the conductor of the ceramic substrate via the via-hole conductor. It is also possible to use a method in which the resin sheet is wrapped around the outer peripheral portion of the external terminal electrode after being connected to the pattern, the resin sheet is thermoset, the support is then peeled off, and the external terminal electrode is transferred to the resin sheet. .
In this method, the multilayer electronic component according to claim 4 can be manufactured with one resin layer without using two resin layers.
In this case, as a support body, you may use the support plate which affixed metal foil via the adhesive, and the support plate which affixed metal foil via the adhesive sheet. For example, when using a support plate with a metal foil attached via an adhesive sheet, when the support is pressure-bonded with a resin sheet on the lower surface of the ceramic substrate, the stain permeates due to the relationship between the resin exudation force and the adhesive force. By controlling the amount of protrusion, the resin can go around the outer periphery of the external terminal electrode. Since the resin oozes out from the surroundings, the amount of oozing is small when the adhesive strength is strong, and the amount of oozing out is large when the adhesive strength is weak.

According to the first aspect of the invention, since the outer peripheral portion of the external terminal electrode is embedded in the resin layer, the periphery of the external terminal electrode is physically made of resin in addition to the bonding force between the external terminal electrode and the resin layer. Therefore, even if a force in the peeling direction acts on the external terminal electrode due to thermal expansion or a drop impact of the via-hole conductor, it is possible to reliably prevent the external terminal electrode from peeling off. And since the circumference | surroundings of the external terminal electrode are covered with resin, the solder does not spread more than necessary, and thereby the peeling force collects in the vicinity of the central portion, and it becomes more difficult to peel off.
Since the lower surface of the resin layer is flat, when mounted on a mother board or the like, it can be stably mounted, and flux residues and the like are not easily accumulated.
Further, since the material covering the outer peripheral portion of the external terminal electrode is a resin, even if the thickness of the resin layer is thin, the resin layer is not baked, so there is no difference in shrinkage from the electrode, and cracking of the resin layer can be prevented.
Since the lower surface of the external terminal electrode is located above the lower surface of the resin layer, when moisture is trapped in the electrode, the moisture trapped during reflow vaporizes and expands, and passes through the molten solder to the outside. Even if it is released, the wall surface of the resin layer surrounding the external terminal electrode can prevent the solder from scattering.

According to the invention of claim 4, the lower surface of the central portion of the external terminal electrode and the lower surface of the resin layer are formed on the same plane, the lower surface of the outer peripheral portion of the external terminal electrode is located above the lower surface of the central portion, Since the resin layer wraps around the lower surface of the outer peripheral portion of the electrode, it is possible to prevent the external terminal electrode from being peeled off as in the case of claim 1 and to prevent the residue of the flux from accumulating and to prevent the resin layer from cracking.
Furthermore, since the lower surface of the central portion of the external terminal electrode and the lower surface of the resin layer are on the same plane, there is an advantage that when the electronic component is mounted on a motherboard or the like, stable mounting is possible.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of a multilayer electronic component according to the present invention.
The multilayer electronic component A includes a ceramic multilayer substrate 1 composed of a plurality of ceramic layers and a resin layer 10 fixed to the lower surface of the ceramic multilayer substrate 1.

The ceramic multilayer substrate 1 is made of, for example, LTCC, and is formed by laminating a plurality of ceramic layers, providing an internal conductor 2 between the layers, and providing a via-hole conductor 3 penetrating the ceramic layer in the thickness direction. ing. A multilayer capacitor, a multilayer inductor, and the like can be integrally formed on the ceramic multilayer substrate 1. Element connection pad electrodes 4 and 5 are formed on the upper and lower surfaces of the ceramic multilayer substrate 1.

A first circuit element 16 is fixed to the pad electrode 4 on the upper surface of the ceramic multilayer substrate 1, and a second circuit element 17 is connected to the pad electrode 5 on the lower surface. As these circuit elements 16 and 17, semiconductor devices such as IC, LSI, diode, and transistor, and passive elements such as a chip capacitor, a chip resistor, a chip thermistor, a chip inductor, and a filter can be used. As a method for connecting the circuit elements 16 and 17, the circuit elements 16 and 17 may be connected by solder or a conductive adhesive, may be connected using bumps, or may be connected by wire bonding.

The resin layer 10 is a mixture of an inorganic filler (Al ₂ O ₃ , SiO ₂ , TiO _2, etc.) in a thermosetting resin (epoxy, phenol, cyanate, etc.), and is fixed to the lower surface of the ceramic multilayer substrate 1. The circuit element 17 is fixed so as to wrap around and hardened. The resin layer 10 has a two-layer structure of a first resin layer 11 fixed to the lower surface of the ceramic multilayer substrate 1 and a second resin layer 12 fixed to the lower surface of the first resin layer 11. The circuit element 17 fixed to the lower surface of the multilayer substrate 1 is embedded in the first resin layer 11. A plurality of external terminal electrodes 13 are formed at the interface between the first resin layer 11 and the second resin layer 12, and the central portion of the external terminal electrodes 13 is formed on the lower surface of the flat second resin layer 12. The exposed hole 14 is exposed to the outside. That is, as shown in FIG. 2, the inner peripheral portion 14a of the exposed hole 14 of the second resin layer 12 covers the entire outer periphery of the external terminal electrode 13, and the lower surface of the external terminal electrode 13 is the second surface. It is located above the lower surface of the resin layer 12. Here, the external terminal electrodes 13 and the exposure holes 14 are rectangular, but may be any shape such as a circle or an oval.
The first resin layer 11 and the second resin layer 12 are desirably made of the same material, the thermosetting resin as the main agent, in order to increase the bonding strength and reduce the difference in thermal expansion.

In this embodiment, the external terminal electrode 13 is formed of a metal foil, for example, a copper foil. The external terminal electrode 13 is made of a metal foil instead of a thick film electrode because it is on the resin layer 10 (11, 12) side and cannot be fired, and the combination of the metal foil and the resin is a printed wiring board. This is because the manufacturing method can be applied. The external terminal electrode 13 is formed at a position corresponding to the upper and lower sides of the relay electrode 6 formed on the lower surface of the ceramic multilayer substrate 1, and these electrodes 13, 6 penetrate via the first resin layer 11 in the thickness direction. 15 is conducting. The relay electrodes 6 are not limited to those formed individually on the lower surface of the ceramic multilayer substrate 1, but can also be used at the end portion of the via-hole conductor 3 exposed on the lower surface of the ceramic multilayer substrate 1. The relay electrode 6 may also serve as the pad electrode 5.

As described above, the inner peripheral portion 14 a of the exposed hole 14 of the second resin layer 12 covers the outer peripheral portion of the external terminal electrode 13. That is, the second resin layer 12 functions as a framing layer of the external terminal electrode 13, and the external terminal electrode 13 is difficult to peel off. Therefore, when the multilayer electronic component A is mounted on a printed circuit board or the like, a drop impact or the like acts, and when a force for peeling the printed circuit board and the multilayer electronic component A acts, the external terminal electrode 13 is connected via solder. The entire surface is pulled, and the external terminal electrode 13 and the resin layer 10 may be peeled off starting from the outer peripheral portion of the external terminal electrode 13, but the second resin layer 12 presses the outer peripheral portion of the external terminal electrode 13. The external terminal electrode 13 can be prevented from peeling off. The via-hole conductor 15 generally has a larger coefficient of thermal expansion than the resin constituting the resin layer 10, and the via-hole conductor 15 is raised by heat such as reflow, and a force in the direction of peeling off the external terminal electrode 13 acts. Also, since the second resin layer 12 holds down against the peeling force, it is possible to prevent the external terminal electrode 13 from being peeled off and at the same time to prevent poor conduction between the external terminal electrode 13 and the via-hole conductor 15.

Next, an example of a manufacturing method of the multilayer electronic component A shown in FIG. 1 will be described with reference to FIG.
First, as shown in FIG. 3A, the ceramic multilayer substrate 1, the resin sheet 10, and the support 22 are prepared. The ceramic multilayer substrate 1 is manufactured as follows.
A ceramic slurry is applied on a resin film such as PET and dried to obtain a ceramic green sheet having a thickness of about 10 to 200 μm. As the ceramic powder contained in the ceramic slurry, for example, a mixture of BaO, SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , CaO or the like can be used.
A through hole (via hole) having a diameter of about 0.1 mm is formed in the green sheet with a mold, a laser, or the like, and a conductive paste kneaded with metal powder, resin, or organic solvent mainly composed of Ag or Cu is filled in the via hole, dry. This becomes the via-hole conductor 3.
A conductive paste similar to the above is printed in a desired pattern on the green sheet by screen printing or the like and dried. This is the inner conductor 2.
An appropriate number of green sheets are stacked and pressure-bonded at a pressure of 100 to 2000 kgf / cm ² and a temperature of about 40 to 100 ° C.
The element connection pad electrodes 4 and 5 and the relay electrode 6 are formed on the front and back surfaces of the laminated body by using the same conductive paste as described above.
Next, if the conductive paste is Ag-based, the laminate is fired at about 850 ° C. in the air, and if Cu-based, the laminate is fired at about 950 ° C. in N ₂ . The thickness of the laminated body is, for example, about 1 mm.
After firing, if necessary, Ni / Sn or Ni / Au or the like is formed on the electrodes exposed on the front and back surfaces by plating or the like.
The ceramic multilayer substrate 1 is manufactured as described above.
Thereafter, the circuit element 17 is connected to the pad electrode 5 on the back surface of the ceramic multilayer substrate 1.

On the other hand, a copper foil having a thickness of about 10 to 40 μm is plated or pasted on a support 22 such as a metal plate, and the copper foil is patterned through steps of photoresist coating, exposure, development etching, and resist stripping. This becomes the external terminal electrode 13.
Furthermore, a semi-cured first resin sheet 11 is prepared. This resin sheet 11 is obtained by mixing an inorganic filler (Al ₂ O ₃ , SiO ₂ , TiO _2, etc.) in a thermosetting resin (epoxy, phenol, cyanate, etc.), and a via hole for conduction with a laser or the like. Open 15a. The semi-cured state refers to a B stage state or a prepreg state. A conductive resin (a mixture of metal particles such as Au, Ag, Cu, and Ni and a thermosetting resin such as epoxy, phenol, and cyanate) is filled in the via hole 15a. In addition, when filling the via hole 15a with solder, it may be filled by reflow or the like after pressure bonding with the ceramic multilayer substrate 1.
When the thickness of the ceramic multilayer substrate 1A is 1 mm, the thickness of the first resin sheet 11 is preferably about 400 μm.

The support 22 and the ceramic multilayer substrate 1 prepared as described above are positioned with the first resin sheet 11 in between, and are thermocompression bonded.
By the thermocompression bonding, the semi-cured resin sheet 10 is pressure-bonded to the lower surface of the ceramic multilayer substrate 1 and simultaneously filled in the gaps between the circuit elements 17. Note that if the first resin sheet 11 is pressure-bonded while being evacuated, air entrained between the ceramic multilayer substrate 1 and the resin sheet 11 can be well eliminated.
By thermocompression bonding, the via-hole conductor 15 provided in the resin sheet 11 is cured, and is electrically connected to the relay electrode 6 on the lower surface of the ceramic multilayer substrate 1 and is also electrically connected to the external terminal electrode 13.
When the support 22 is peeled off from the resin layer 11 after the resin sheet 11 is heat-cured, the copper foil attached to the support 22 is transferred to the resin layer 11 and becomes the external terminal electrode 13 ((b in FIG. 3). )reference).

Next, the support 23 is positioned with the second resin sheet 12 interposed between the lower surface of the composite laminate that has been pressure-bonded as shown in FIG.
In the resin sheet 12, an exposure hole 14 smaller than the external terminal electrode 13 is formed at a position corresponding to the external terminal electrode 13.
By thermocompression bonding, the second resin sheet 12 is fixed to the lower surface of the first resin layer 11 and becomes an integral resin layer 10. At this time, since the inner peripheral portion of the exposed hole 14 of the resin sheet 12 covers the entire outer peripheral portion of the external terminal electrode 13, it is possible to reliably prevent the external terminal electrode 13 from peeling off.
When the support 23 is peeled from the second resin layer 12 after the heat curing of the resin sheet 12, the flatness of the surface of the support 23 is transferred to the resin layer 12, and the lower surface of the second resin layer 12 becomes flat. (See (c) of FIG. 3).

After that, the circuit element 16 is connected to the pad electrode 4 provided on the upper surface of the composite laminate that has been crimped as shown in FIG. Part A is completed.
In FIG. 3, the manufacturing method of the single multilayer electronic component A has been described. However, in actuality, the ceramic multilayer substrate 1 and the resin sheets 11 and 12 are pressure-bonded and cured in the parent substrate state, and then the individual pieces are obtained. A method of forming the multilayer electronic component A is adopted by dividing into two. Examples of the division method include a break method and a dicer cutting method.

FIG. 4 shows a second embodiment of the multilayer electronic component.
In the case of the multilayer electronic component shown in FIG. 1, since the circuit element 16 connected to the upper surface of the ceramic multilayer substrate 1 is exposed, the circuit element 15 easily falls off when an external force is applied, and cannot be adsorbed by the mounter. Therefore, in FIG. 4, a case 20 covering the circuit element 16 is put on the surface of the ceramic multilayer substrate 1. As the case 20, a resin case or a metal case can be used. In the case of the metal case 20, white or phosphor bronze is preferable in terms of ease of processing and cost. In the case of a metal case, the electromagnetic shielding of the circuit element 16 becomes possible.

FIG. 5 shows a third embodiment of the multilayer electronic component.
In this embodiment, a resin 21 is molded on the upper surface of the ceramic multilayer substrate 1 so as to cover the circuit element 16. In this case, if the thermal expansion coefficients of the resin layers 10 and 21 on the front and back sides of the ceramic multilayer substrate 1 are different, the substrate 1 may be warped or cracked due to thermal history. Therefore, it is preferable to use both resins 10 and 21 having the same composition or a material having a thermal expansion coefficient close to the extent that the ceramic multilayer substrate 1 is not warped due to thermal history.

FIG. 6 shows a fourth embodiment of the multilayer electronic component.
In this embodiment, the electrode 7 occupying 20 to 80% of the bottom area of the ceramic multilayer substrate 1 is disposed at the interface between the ceramic multilayer substrate 1 and the resin layer 10, so that the ceramic multilayer substrate 1 and the resin layer 10 are arranged. The bonding strength is increased. In particular, this electrode 7 is preferably not an metal foil but an electrode (sintered metal) obtained by sintering a conductive paste. This is because the surface roughness of the sintered metal is rough (R _max = several tens μm order) compared to the surface roughness of the metal foil (copper foil) (R _max = several μm order). This is because the bonding strength can be increased. The difference in surface roughness is that the copper foil is formed by plating or rolling of a copper plate, whereas the sintered metal is obtained by sintering a conductive paste, and the pores due to the scattering of the resin during the firing are on the surface. This is due to remaining inside. The electrode 7 may be connected to the internal conductor 2 of the ceramic multilayer substrate 1 via the via-hole conductor 3 or may be electrically independent from the internal conductor 2.
The electrode 7 is preferably a ground electrode. The ground electrode can secure a shielding property between the ceramic multilayer substrate 1 and the mother board. In addition, it is preferable that the ground electrode and the mother board are closer because the distance connecting the ground electrode and the mother board ground electrode becomes shorter and the parasitic inductance value becomes smaller.

FIG. 7 shows a fifth embodiment of the multilayer electronic component.
In this embodiment, the resin layer 10 is composed of one layer. In this case, the lower surface of the resin layer 10 is formed flat, the lower surface of the central portion of the external terminal electrode 13 and the lower surface of the resin layer 10 are formed on the same plane, and almost the entire circumference of the lower surface of the outer peripheral portion of the external terminal electrode 13 is formed. It is located above the lower surface of the central part. That is, the outer peripheral portion 13a of the external terminal electrode 13 is slightly warped upward. The central portion of the external terminal electrode 13 is exposed from the resin layer 10, and the entire outer periphery 13 a of the external terminal electrode 13 is covered with the resin layer 10.
Also in this case, covering the entire outer periphery of the external terminal electrode 13 with the resin layer 10 has an effect of preventing the external terminal electrode 13 from peeling off.

FIG. 8 shows a part of the manufacturing process of the multilayer electronic component shown in FIG.
As shown in FIG. 8A, a semi-cured resin sheet 10 is disposed between the ceramic multilayer substrate 1 and the support 24, and heat-pressed up and down. An external terminal electrode 13 made of a metal foil (for example, copper foil) is attached to the upper surface of the support 24 via an adhesive sheet 25. A part of the resin enters the interface between the pressure-sensitive adhesive sheet 25 and the external terminal electrode 13 due to the pressure of the resin sheet 10 at the time of pressure bonding. That is, by controlling the amount of resin penetration by the relationship between the adhesive force of the adhesive sheet 25 and the applied pressure of the resin, the resin can be made to wrap around almost the entire outer periphery of the external terminal electrode.
When heat-cured in this state, the outer peripheral portion of the external terminal electrode 13 is embedded in the resin layer 10 as shown in FIG.
In FIG. 8, a resin sheet having a constant thickness is used as the semi-cured resin sheet 1. However, only the outer peripheral portion of the external terminal electrode 13 is thinned, or the outer peripheral portion of the external terminal electrode 13 in the adhesive sheet 25. You may accelerate | stimulate penetration of resin by making the adhesive force of a corresponding part low.

1 is a cross-sectional view of a first embodiment of a multilayer electronic component according to the present invention. FIG. 2 is an enlarged cross-sectional view and a bottom view of an external terminal electrode portion of the multilayer electronic component shown in FIG. 1. FIG. 2 is a process diagram showing a manufacturing process of the multilayer electronic component shown in FIG. 1. It is sectional drawing of 2nd Example of the multilayer electronic component concerning this invention. It is sectional drawing of 3rd Example of the multilayer electronic component concerning this invention. It is sectional drawing of the 4th Example of the multilayer electronic component concerning this invention. It is sectional drawing of the 5th Example of the multilayer electronic component concerning this invention. FIG. 8 is a process diagram illustrating a part of the manufacturing process of the multilayer electronic component illustrated in FIG. 7.

Explanation of symbols

A multilayer electronic component 1 ceramic multilayer substrate 10 resin layer 11 first resin layer 12 second resin layer 13 external terminal electrode 14 exposed hole 15 via-hole conductors 16 and 17 circuit element 20 mold resin 21 case

Claims (9)

A ceramic substrate on which a conductor pattern is formed;
A resin layer fixed to the lower surface of the ceramic substrate;
In a multilayer electronic component comprising an external terminal electrode exposed from the lower surface of the resin layer and connected to the conductor pattern of the ceramic substrate via a via-hole conductor provided in the resin layer,
The lower surface of the resin layer is formed flat,
The lower surface of the external terminal electrode is located above the lower surface of the resin layer,
A multilayer electronic component, wherein a central portion of the external terminal electrode is exposed from the resin layer, and an outer peripheral portion of the external terminal electrode is covered with the resin layer. 2. The multilayer electronic component according to claim 1, wherein a difference in height between a lower surface of the external terminal electrode and a lower surface of the resin layer is 5 to 100 μm. The resin layer is composed of a first resin layer fixed to the lower surface of the ceramic substrate and a second resin layer fixed to the lower surface of the first resin layer,
The external terminal electrode is formed at the interface between the first resin layer and the second resin layer,
3. The stacked type according to claim 1, wherein the second resin layer is provided with an exposed hole that exposes a central portion of the external terminal electrode and covers substantially the entire circumference of the outer peripheral portion. 4. Electronic components. A ceramic substrate on which a conductor pattern is formed;
A resin layer fixed to the lower surface of the ceramic substrate;
In a multilayer electronic component comprising an external terminal electrode exposed from the lower surface of the resin layer and connected to the conductor pattern of the ceramic substrate via a via-hole conductor provided in the resin layer,
The lower surface of the resin layer is formed flat,
The lower surface of the central portion of the external terminal electrode and the lower surface of the resin layer are formed on the same plane,
The outer peripheral lower surface of the external terminal electrode is located above the lower central surface,
A multilayer electronic component, wherein a central portion of the external terminal electrode is exposed from the resin layer, and an outer peripheral portion of the external terminal electrode is covered with the resin layer. 5. The multilayer electronic component according to claim 1, wherein the external terminal electrode is made of a Cu foil having a Ni—Au plating surface. 6. The ceramic substrate according to claim 1, wherein the ceramic substrate is a low-temperature fired ceramic multilayer substrate in which a plurality of ceramic layers are laminated, and a conductor pattern mainly composed of Ag or Cu is formed therein. The multilayer electronic component according to any one of the above. The multilayer electronic component according to any one of claims 1 to 6, further comprising a circuit element connected to a lower surface of the ceramic substrate and embedded in the resin layer. Preparing a ceramic substrate on which a conductor pattern is formed;
Preparing a first resin sheet containing a thermosetting resin in a semi-cured state and having a via-hole conductor;
Preparing a second resin sheet containing a semi-cured thermosetting resin and having an exposed hole at a position corresponding to the external terminal electrode;
Preparing a support to which external terminal electrodes made of metal foil are attached;
The support is pressure-bonded with the first resin sheet interposed between the lower surface of the ceramic substrate, the external terminal electrode is fixed to the lower surface of the first resin sheet, and the external terminal electrode is connected to the ceramic substrate via a via-hole conductor. Connecting with the conductor pattern of
Thermosetting the first resin sheet;
Peeling the support from the first resin sheet and transferring the external terminal electrode to the first resin sheet;
Crimping the second resin sheet to the lower surface of the first resin sheet so that the outer periphery of the external terminal electrode is covered by the inner periphery of the exposed hole;
And a step of thermosetting the second resin sheet. A method of manufacturing a multilayer electronic component, comprising: Preparing a ceramic substrate on which a conductor pattern is formed;
Including a semi-cured thermosetting resin and preparing a resin sheet having a via-hole conductor;
Preparing a support to which external terminal electrodes made of metal foil are attached;
The support is bonded to the lower surface of the ceramic substrate with the resin sheet interposed therebetween, and external terminal electrodes are fixed to the lower surface of the resin sheet, and the external terminal electrodes are connected to the conductor pattern of the ceramic substrate via via-hole conductors. Connecting the resin sheet around the outer periphery of the external terminal electrode; and
A step of thermosetting the resin sheet;
Peeling the said support body, and transferring the external terminal electrode to the said resin sheet, The manufacturing method of a multilayer electronic component characterized by the above-mentioned.

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