JP2004273694A - Multilayer ceramic substrate and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer ceramic substrate having independently raised projections and to provide a method for manufacturing the same. <P>SOLUTION: A release layer is superposed on a substrate 1 except for portions that correspond to plane shapes of the projections 2a-2c, and further a laminated body is formed on the substrate 1 by interposing the release layer. The entirety of the laminate is then crimped, followed by notching the upper laminated body along the plane shapes of the projections 2a-2c and removing the laminated body on the release layer to form the projections 2a-2c. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multilayer ceramic substrate having a protrusion on a ceramic substrate formed by laminating a plurality of ceramic sheets, for example, and a method for manufacturing the same.
[0002]
[Prior art]
Ceramic multilayer circuit boards (multilayer ceramic boards) used for small electronic devices have a structure in which a plurality of ceramic green sheets are laminated as required. Some of the layers of the substrate have holes (cavities) in which electronic components such as chip components can be mounted.
[0003]
As a method generally known as a method of forming a cavity in a multilayer ceramic substrate, for example, there is a method disclosed in Patent Document 1. In the multilayer ceramic substrate described in Patent Document 1, a cavity is formed by overlapping through holes provided in each of a plurality of ceramic layers. That is, an opening is formed in each green sheet in advance, and these green sheets are sequentially stacked to produce a laminate, thereby forming a cavity.
[0004]
For example, Patent Document 2 discloses a multilayer ceramic substrate including a cavity having a special opening shape. The multilayer ceramic substrate described in Patent Document 2 is a ceramic multilayer circuit substrate in which a plurality of ceramic green sheets are stacked to provide a protrusion protruding from the side wall of the cavity, and the opening area of the cavity can be reduced by the protrusion. Is to provide.
[0005]
[Patent Document 1]
JP-A-2001-267448 [0006]
[Patent Document 2]
Japanese Patent Laid-Open No. 2002-76188
[Problems to be solved by the invention]
On the other hand, there is a case where a projecting portion that does not contact the side wall of the cavity, that is, a projecting portion that stands independently in the cavity may be required due to the design requirements of the circuit board. Such a protrusion is used for, for example, incorporating a circuit therein or mounting a component on the upper portion of the protrusion.
[0008]
However, since both the conventional laminating method and the laminating technique are to stack green sheets in which openings having a specific shape are formed in advance, as described above, the protrusions independent from the side walls of the cavities, There is a problem that it cannot be created simultaneously with the formation of the cavity.
[0009]
Here, paying attention to the method of forming the protruding portion in the cavity, for example, a single layer formed separately from the laminated body is placed in the cavity and thermocompression-bonded, or in the cavity of the substrate after firing. A method of adhering the laminated single body is conceivable. However, the process of disposing the single layer in the cavity and bonding it is complicated, and high positional accuracy is required when it is necessary to electrically connect the single layer and the substrate. For this reason, the productivity of the circuit board is inferior, and in addition, there is a problem that the reliability of the connection portion between the single laminated body and the board is low.
[0010]
[Means for Solving the Problems]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a multilayer ceramic substrate having a cavity on the substrate and a protruding portion that stands independently in the cavity, and a method for manufacturing the same. That is.
[0011]
Another object of the present invention is to provide a multilayer ceramic substrate and a manufacturing method thereof for forming a protrusion on the substrate by a simple process.
[0012]
For example, the following configuration is provided as a means for achieving the object and solving the above-described problems. That is, a method for producing a multilayer ceramic substrate having a plurality of ceramic sheets laminated and having a protruding portion at least partially, wherein the release layer is formed on the substrate except for a portion that matches the planar shape of the protruding portion. After forming the laminate on the substrate on which the release layer is formed and pressurizing, the protrusion formed by removing the laminate formed on the release layer It is characterized by doing.
[0013]
As another means for solving the above-described problem, for example, the following configuration is provided. That is, a method for manufacturing a multilayer ceramic substrate having a protruding portion on a surface, wherein an opening is provided between the step of forming a first laminated portion by laminating ceramic sheets and the first laminated portion. The step comprises forming a second laminated portion by laminating ceramic sheets with a release layer interposed therebetween, the first laminated portion, the release layer, and the second laminated portion. Pressurizing the laminated body, forming a notch corresponding to the opening in the second laminated portion, and forming the first laminated portion around the opening according to the notch in the first And removing from the stacked portion, and forming the protruding portion having a planar shape corresponding to the shape of the opening.
[0014]
For example, the release layer is thinner than the ceramic sheet. In addition, for example, the protruding portion is formed on the first stacked portion at a position separated from a peripheral portion of the first stacked portion.
[0015]
For example, the release layer is a film coated with a release agent. For example, the release layer is formed by printing a release agent on a ceramic sheet.
[0016]
For example, after the step of forming the notch, the second stacked portion around the opening is removed after the temperature of the stacked body is lowered. Further, for example, a display showing the position of the cut is arranged on the laminate.
[0017]
As another means for solving the above-described problem, for example, the following configuration is provided. That is, the multilayer ceramic substrate is manufactured by the above-described method for manufacturing a multilayer ceramic substrate.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
Hereinafter, a first exemplary embodiment according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows the appearance of a ceramic multilayer circuit board (multilayer ceramic substrate) according to the first embodiment. 1A is a plan view of the substrate as viewed from above, FIG. 1B is a front view thereof, and FIG. 1C is a cross-sectional view of the substrate cut from a substantially central portion. In addition, this multilayer ceramic substrate is produced through the process mentioned later.
[0019]
As shown in FIG. 1, the multilayer ceramic substrate has three protrusions 2 a to 2 c formed on the upper surface of the substrate 1, and these protrusions 2 a to 2 c are formed from the peripheral edge 4 of the substrate 1. It is formed at a position separated by a predetermined distance. That is, the protrusions 2 a to 2 c stand on the substrate in a state where they do not contact any peripheral edge on the surface of the substrate 1.
[0020]
As shown in FIG. 1C, via holes / circuit patterns 5a and 5c as internal conductors are formed inside the protrusions 2a and 2c. Further, as shown in FIGS. 1A and 1C, a via hole / circuit pattern 5b is formed in the protrusion 2b, and an electrode 3 as an external conductor is formed on the upper end surface thereof. Has been. Moreover, you may form the electrodes 3a and 3b in the side surface of the protrusion part 2b.
[0021]
FIG. 2 shows the appearance of a sheet used for the multilayer ceramic substrate according to this embodiment. (A) of the figure is a ceramic green sheet 10 (also referred to as a ceramic sheet or a green sheet) used for forming a laminate of substrates, and has a rectangular shape corresponding to the size of the substrate to be manufactured. The green sheet 10 may be manufactured in a substrate unit size, or may be manufactured using a large number of substrates, and then divided into individual substrates.
[0022]
FIG. 2B is an external plan view of a film constituting a release layer for forming a protruding portion in a substrate manufacturing process described later. The film 15 is provided with holes (openings or punched portions) 12a to 12c at positions corresponding to the positions of the protrusions formed on the substrate and the planar shape of the protrusions. The surface of the film 15 is coated with a release agent.
[0023]
The thickness of the film 15 is thinner than the green sheet 10 used for forming the laminate, and is made of a material that does not deform or break due to heat applied in the press-bonding process described later. For example, a pet film is used as the film 15. The reason why a thin material is used as the film 15 is that if the film 15 is thicker than the green sheet 10, the flatness of the top of the protrusion is impaired.
[0024]
Next, a manufacturing process of the multilayer ceramic substrate according to the present embodiment will be described in detail. FIG. 3 shows a manufacturing process of the multilayer ceramic substrate according to the present embodiment in time series. In each process drawing referred to in the following description, illustration of via holes and circuit patterns inside the substrate and inside the protrusions is omitted.
[0025]
FIG. 3A shows a step of forming a base portion of a multilayer ceramic substrate. Here, three green sheets 21 to 23 are laminated to form a substrate (first laminated portion). The number of stacked layers can be adjusted as appropriate. For example, if a green sheet has a thickness of 100 μm, 10 sheets are stacked to obtain a desired thickness. In addition, a dedicated sheet stacking jig (not shown) is used for the stacking operation.
[0026]
In the subsequent step shown in FIG. 3B, the above-described film 15 (release layer) is formed on the laminated green sheet 21 at the top. The film 15 is, for example, a pet film having a thickness of 50 μm, and an opening of the film 15 indicated by a thick line in FIG. 3B corresponds to a position where a protrusion is formed on the substrate. In the present embodiment, the opening of the film 15 is rectangular (for example, a 1 mm square opening) (see the openings 12a to 12c in FIG. 2).
[0027]
In the step shown in FIG. 3C, three green sheets 25 to 27 are further laminated on the green sheets 21 to 23 and the film 15 laminated in the above step (second lamination portion). These green sheets 25 to 27 are stacked so that the total thickness of the green sheets 25 to 27 is substantially equal to the height of the protrusions to be formed on the substrate (shrinks somewhat by firing). Also in this step, as described above, for example, if a green sheet having a thickness of 100 μm is used, ten of them are stacked to ensure a thickness corresponding to the height of the protruding portion.
[0028]
In addition, on the surface of the uppermost sheet 25 of the green sheets 25 to 27, a mark display (cutting mark) 28 corresponding to the planar shape of the protruding portion used when the protruding portion is cut out in a process described later is provided. Provide. Note that the mark display 28 may not be provided at a position corresponding to the planar shape of the protruding portion, but may be provided, for example, at the peripheral edge of the surface of the multi-piece substrate. Moreover, the display method of the mark display 28 should just be a method which can identify a display part clearly, such as printing and embossing, for example.
[0029]
The subsequent step shown in FIG. 3D is a pressing step. For example, the isostatic pressing method is applied to the green sheet laminate shown in FIG. Apply external force and crimp the entire surface of the green sheet. Specifically, the obtained laminate was put in a plastic bag together with a lamination jig and vacuum packed. And it put into the hydrostatic pressure press apparatus and pressed with the pressure of about 350 Kgf / cm < ² >.
[0030]
Note that the method of applying the pressing pressure for forming the laminate is not limited to the isostatic pressing method, and other methods such as a uniaxial pressing method may be used.
[0031]
In the production of the multilayer ceramic substrate according to the present embodiment, any green sheets 21 to 23, 25 to 27 to be used except for the film 15 have no opening for forming the protruding portion. Therefore, there is no “displacement” in the stacking of the sheets between the layers during the laminating and pressing. As a result, a laminated body in a good laminated state can be obtained.
[0032]
After applying the pressing pressure described above, the laminated body removed from the laminating jig is maintained at a temperature of 70 ° C., and in the step shown in FIG. Insert. In FIG. 3E and subsequent figures, the left side is a front view and the right side is a side view. The depth at which the blade 31 is applied to the mark display 28 to make a cut can be predicted by the number of stacked green sheets.
[0033]
In addition, since the green sheets 21 to 23 and 25 to 27 have thermoplasticity, the blade 31 can be easily inserted into the laminated body 30 by heating the laminated body 30 in this cutting process.
[0034]
(F) of FIG. 3 has shown the state when the notch | incision to the laminated body 30 is complete | finished, and the notch 32 corresponding to opening part 12a-12c is along the planar shape of the protrusion part to form, It can be seen that the film reaches a depth that reaches the film 15. The laminated body 30 containing these cuts 32 is allowed to stand until the room temperature is reached, and then the pressure-bonded bodies 35a to 35f on the film 15 are removed. As described above, since the release agent is coated on the surface of the film 15, the pressure-bonding bodies 35a to 35f on the film can be easily removed.
[0035]
Here, the reason why the laminated body 30 with the cuts 32 is allowed to stand until it reaches room temperature is that if the pressure-bonding bodies 35a to 35f are removed when the laminated body 30 is in a soft state, the protrusions may be distorted. is there. Accordingly, the pressure-bonding bodies 35a to 35f are removed after the temperature of the stacked body 30 is lowered and is cured to some extent. By carrying out like this, since the laminated body 30 hardens to some extent at normal temperature (for example, 30 degrees C or less), it can suppress that a protrusion part is distorted.
[0036]
In FIG. 3G, by removing the pressure-bonding bodies 35 a to 35 f, the laminated body at the upper part of the release layer is removed, and the protrusions 2 a to 2 c are located at the opening positions of the release layer on the substrate 1. It shows the state when formed. In this embodiment, after the degreasing process, the entire substrate 1 on which the protrusions are formed is fired. Specifically, after degreasing at 500 ° C. for 5 hours, baking was performed at 860 ° C. for 10 minutes.
[0037]
FIG. 4 is a flowchart showing a procedure for manufacturing a multilayer ceramic substrate according to the present embodiment. First, in step S11 of the figure, a predetermined number of green sheets are laminated to form a base portion of a multilayer ceramic substrate (see FIG. 3A). In step S12, a pet film having an opening corresponding to the position and size of the protrusion is formed on the stacked uppermost green sheet (see FIG. 3B).
[0038]
In step S13, a predetermined number of green sheets are further laminated on the green sheet and film laminated in the above steps (see FIG. 3C). These green sheets are sheets for forming protrusions. Here, as described above, a number of sheets equal to the height of the protrusions are stacked.
[0039]
In subsequent step S15, an external force is applied to the green sheet laminate by, for example, an isostatic pressing method, and the entire green sheet is pressure-bonded (see FIG. 3D). After the press pressure is applied, in step S16, the laminate in the high temperature state is cut up to the depth reaching the pet film according to the mark provided on the uppermost green sheet in advance (FIGS. 3E and 3F). )reference).
[0040]
In step S21, the laminated body that has been cut in the above step is left unattended, and in step S22, it is determined whether or not the laminated body has reached room temperature. That is, the laminate is left until it reaches room temperature. When the laminated body reaches room temperature, only the pressure-bonding body (laminated body) on the film is removed (step S25).
[0041]
In step S27, which is the final step, the pressure-bonded body is removed as described above, and the substrate on which the protrusions are formed is degreased and fired (see FIG. 3G).
[0042]
[Second Embodiment]
Next, a second embodiment according to the present invention will be described in detail. FIG. 5 shows a multilayer ceramic substrate according to the second embodiment. As shown in FIGS. 5A and 5B, the multilayer ceramic substrate according to the second embodiment has side walls around the substrate, and FIG. The top view seen from the top and (b) are sectional views when the substrate is cut from the substantially central portion.
[0043]
Similarly to the substrate according to the first embodiment shown in FIG. 1, the multilayer ceramic substrate shown in FIG. 5 also has protrusions 52a to 52c formed at positions separated from the peripheral edge of the base substrate by a predetermined distance. Further, via holes / circuit patterns 55a, 55b, and 55c are formed inside these protrusions, and an electrode 53 is formed on the upper end surface of the protrusion 52b.
[0044]
The side wall 57 provided at the peripheral edge of the base substrate is formed after forming a laminated body having projecting portions 52a to 52c according to the same process as the multilayer ceramic substrate according to the first embodiment described above shown in FIG. Further, it can be formed by laminating green sheets constituting the side wall 57 (as shown in FIG. 6, a frame shape corresponding to the planar shape of the side wall 57 in advance) and pressing the laminated body. .
[0045]
FIG. 6 is an external perspective view of the multilayer ceramic substrate according to the second embodiment. 6A shows a manufacturing process of the multilayer ceramic substrate according to the second embodiment, and FIG. 6B shows a cavity manufactured by the method according to the second embodiment. It is an external appearance perspective view of the multilayer ceramic substrate which has this.
[0046]
As shown in FIG. 6A, the multilayer ceramic substrate according to the second embodiment is a substrate 61 and a multilayer ceramic substrate having protrusions 52a to 52c formed on the substrate 61. A cavity is formed on the multilayer ceramic substrate. That is, a plurality of frame-shaped ceramic green sheets 82 each having openings (openings for forming cavities) 81 corresponding to the cavities are overlapped, and aligned with the substrate 61 to form a substrate. After laminating on 61, a process of applying a press pressure again is performed. As a result, as shown in FIG. 6B, a multilayer ceramic substrate having a cavity 80 and its side wall 57 is obtained.
[0047]
The shape of the opening 81 is, for example, a rectangle, and the size thereof is such that the protrusions 52 a to 52 c are separated from the peripheral edge of the base substrate 61 by a predetermined distance, and are also separated from the side wall 57 of the cavity 80 by a certain distance. The size formed at the position.
[0048]
The height of the side wall 57 may be the same height as the protrusions 52a to 52c, or the side wall 57 may be higher than the protrusions 52a to 52c (FIG. 5B) This is an example in which the height of the side wall 57 is higher than the protrusions 52a to 52c). In any case, the height of the side wall 57 can be adjusted by the number of stacked green sheets 82 shown in FIG.
[0049]
As another method of forming the side wall 57, there is a method of directly forming a release layer on a green sheet. For example, as shown in FIG. 7, a release layer 105 having the pattern shown in FIG. The release layer 105 is obtained by screen-printing a release agent, and no release agent is applied to the portions 101 to 103 corresponding to the planar shapes of the protrusions 52a to 52c shown in FIG. Further, the release agent is not applied to the portion 104 corresponding to the side wall 57.
[0050]
A laminated body having such a green sheet 100 interposed therebetween is formed, and then the obtained pressure bonding is performed in the multilayer ceramic substrate according to the above-described first embodiment in the same manner as the steps after FIG. Cut into the body to the depth of the release layer 105. And according to the notch, the protrusions 52a-52c and the side wall 57 are formed by removing the laminated body in the area | region which printed the mold release agent of the mold release layer 105. FIG.
[0051]
[Third embodiment]
A third embodiment according to the present invention will be described. The multilayer ceramic substrate according to the third embodiment has a hollow protrusion as shown in FIG. FIG. 8A is a plan view of the multilayer ceramic substrate according to the third embodiment as viewed from above, FIG. 8B is a front view, and FIG. 8C is a cross section when the substrate is cut from a substantially central portion. FIG.
[0052]
In the substrate shown in FIG. 8, a rectangular protrusion 62 and a hollow protrusion 67 are formed on a base substrate 61. Also, a conductor pattern 68 is disposed between the protruding portion 67 on the substrate 61 and the substrate 61, and an electronic component 70 is mounted on the conductor pattern 68 as shown in FIG. . After mounting the electronic component 70, for example, when the lid 69 is placed on the upper portion of the protruding portion 67, the electronic component 70 can be sealed with the protruding portion 67 and the lid 69.
[0053]
For the production of the substrate having the hollow protrusions 67 shown in FIG. 8, for example, a method of directly forming a release layer on the green sheet 100 as in the multilayer ceramic substrate shown in FIG. . Here, instead of the green sheet 100 on which the release layer 105 shown in FIG. 7 is formed, the green sheet 110 on which the release layer 75 shown in FIG. 9 is formed is used.
[0054]
The release layer 75 is formed by patterning a release agent by screen printing, and the release agent is not applied to the portions 71 and 72 corresponding to the planar shape of the projecting portions 62 and 67. That is, the portion 72 to which the release agent is not applied has an annular pattern corresponding to the planar shape of the protruding portion 67.
[0055]
Therefore, a process after FIG. 3 (e) in the multilayer ceramic substrate according to the above-described first embodiment is configured by forming a laminate including the green sheet 110 patterned with such a release agent. Similarly to the above, a cut is made to the depth of the release layer 75 with respect to the obtained pressure-bonded body. Then, according to the cut, the laminate on the area where the release agent of the release layer 75 is printed is removed, whereby the protrusion 62 and the hollow protrusion 67 are formed.
[0056]
The above-described method can significantly improve the productivity of the laminated circuit board as compared to a method of separately bonding a single layer for forming the protrusion, and the circuit pattern can be formed even when the circuit pattern is formed inside the protrusion. And the base substrate can be electrically connected, and the connection between the protruding portion and the side wall and the base substrate can be maintained firmly.
[0057]
Furthermore, by appropriately changing the number of green sheets to be stacked, the height and shape of the protrusions and side walls can be freely set. Moreover, you may use together the method of using the film which has a mold release layer, and the method of forming a mold release layer directly on a green sheet. Further, when a single substrate is formed, it is possible to form a protrusion having a more complicated shape, such as forming a protrusion on the protrusion using a plurality of release layers.
[0058]
【The invention's effect】
As described above, according to the present invention, it is possible to manufacture a multilayer ceramic substrate having a cavity on the substrate and a protruding portion that stands independently in the cavity by a simple process.
[0059]
Further, according to the present invention, the strength of the protruding portion on the substrate is improved, and the connection position accuracy between the protruding portion and the substrate and the reliability of the connecting portion can be maintained high.
[Brief description of the drawings]
FIG. 1 is a diagram showing an appearance of a multilayer ceramic substrate according to a first embodiment of the present invention.
FIG. 2 is a view showing an external shape of a sheet used for the multilayer ceramic substrate according to the first embodiment.
FIG. 3 is a diagram showing a manufacturing process of the multilayer ceramic substrate according to the first embodiment.
FIG. 4 is a flowchart showing a manufacturing procedure of the multilayer ceramic substrate according to the first embodiment.
FIG. 5 is a view showing an appearance of a multilayer ceramic substrate according to a second embodiment of the present invention.
FIG. 6 is an external perspective view of a multilayer ceramic substrate according to a second embodiment.
FIG. 7 is a view showing a green sheet on which a release layer is formed according to a second embodiment.
FIG. 8 is a view showing an appearance of a multilayer ceramic substrate according to a third embodiment of the present invention.
FIG. 9 is a view showing a green sheet used for a multilayer ceramic substrate according to a third embodiment.
[Explanation of symbols]
1, 61 Substrate 2a-2c, 52a-52c, 67 Protruding part 3, 53 Electrode 4 Peripheral part 5a, 5c, 55a, 55b, 55c Via hole / circuit pattern 10, 21-23, 25-27, 82, 100, 110 Green sheets 12a to 12c, 81 Opening 15 Film 30 Laminate 31 Blade 32 Cut 35a to 35f Crimp body 57 Side wall 61 Substrate 68 Conductive pattern 69 Lid 70 Electronic component 80 Cavity

Claims (9)

A method for producing a multilayer ceramic substrate comprising a laminate of a plurality of ceramic sheets and having protrusions at least in part,
A release layer is formed on a substrate except for a portion matched to the planar shape of the protruding portion, and a laminate is further formed on the substrate on which the release layer is formed and pressed, and then the release is performed. A method for producing a multilayer ceramic substrate, wherein the protruding portion is formed by removing the laminate formed on a layer. A method for producing a multilayer ceramic substrate having a protrusion on a surface,
Laminating ceramic sheets to form a first laminated portion;
Interposing a release layer having an opening between the first laminated portion and laminating ceramic sheets to form a second laminated portion;
Pressurizing the laminate composed of the first laminate portion, the release layer, and the second laminate portion;
Forming a notch corresponding to the opening in the second stacked portion;
Removing the second stacked portion around the opening from the first stacked portion according to the notch,
A method for producing a multilayer ceramic substrate, wherein the projecting portion having a planar shape corresponding to the shape of the opening is formed. The method for producing a multilayer ceramic substrate according to claim 1, wherein the release layer is thinner than the ceramic sheet. 3. The method for manufacturing a multilayer ceramic substrate according to claim 1, wherein the protruding portion is formed on the first laminated portion at a position separated from a peripheral portion of the first laminated portion. The method for producing a multilayer ceramic substrate according to claim 1, wherein the release layer is a film coated with a release agent. 5. The method for producing a multilayer ceramic substrate according to claim 1, wherein the release layer is formed by printing a release agent on a ceramic sheet. 7. The second stacked portion around the opening is removed after the temperature of the stacked body is lowered after the step of forming the notch. 7. For producing a multilayer ceramic substrate. The method for manufacturing a multilayer ceramic substrate according to claim 7, wherein an indication indicating the position of the notch is arranged on the laminate. A multilayer ceramic substrate manufactured by the method for manufacturing a multilayer ceramic substrate according to claim 1.

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