JP4310458B2 - Electronic component manufacturing method and electronic component - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an electronic component.
[0002]
[Prior art]
There is a multilayer wiring board as an electronic component of interest for the present invention. In recent years, with the miniaturization of electronic devices such as portable information terminals and computers, further miniaturization is required for multilayer wiring boards built in these electronic devices.
[0003]
This multilayer wiring board is generally composed of a substrate in which multiple insulating layers with wiring layers are stacked and component parts such as IC and LSI mounted on the substrate. One way to achieve this is to increase the packaging density of the component parts. To increase the packaging density, the surface conductor for electrically connecting the component parts and the wiring layer on the board side must be narrowed. It can be formed by pitch.
[0004]
As one method for forming a surface conductor on a substrate, there is a method of screen printing a conductive paste as described in Patent Document 1. However, when a narrow-pitch surface conductor is formed by printing, the solvent component contained in the paste bleeds beyond the intended size intended to be printed, and the metal component contained in the paste flows out into the oozed solvent component later. appear. As a result, a surface conductor having a size larger than the size to be printed is formed. When the surface conductors must be formed at a narrow pitch, different surface conductors may be connected to each other. .
[0005]
Further, in the method by screen printing, when the screen that has been in contact with the substrate at the end of printing is separated from the substrate, a very small amount of paste may be scattered. If this small amount of splatter adheres between the surface conductors formed at a narrow pitch, there is a possibility that the surface conductors are connected to each other. Even if it is not connected at this stage, when the surface conductor is coated by plating before mounting the component parts, the plating is applied even between the surface conductors, and as a result, a short circuit between the surface conductors may occur. Arise.
[0006]
Further, when the electroless plating method is used in the plating process performed before mounting the component parts, as shown in the problem to be solved by the invention of Patent Document 2, cleaning of the Pd activation process is performed. The plating may be coated between the surface conductors due to lack or the like, and as a result, a short circuit between the surface conductors may occur.
[0007]
Such a phenomenon may occur not only by the printing method but also by the transfer method. Transfer is a method of pattern-printing a paste on a carrier film and drying it, and then transferring it onto the main surface of the substrate. However, the above-mentioned bleeding and small amount of splatter may occur on the carrier film in the same way as printing. Because there is, there is a possibility of transferring even unintended things such as blurring and scattering.
[0008]
[Patent Document 1]
JP 2000-183538 A [Patent Document 2]
Japanese Patent Laid-Open No. 10-178273
[Problems to be solved by the invention]
Although these phenomena did not manifest themselves as defects in the era when narrow pitches between surface conductors were not required, the present day where narrow pitches between surface conductors are required due to miniaturization of parts Is a problem to be solved, and is not limited to multilayer wiring boards, but is a problem common to all electronic components.
[0010]
Accordingly, an object of the present invention is to provide an electronic component manufacturing method capable of solving the above-described problems.
[0011]
According to the manufacturing method of the electronic component according to claim 1 of the present invention, to form a plurality of the green sheets preparing step of preparing an insulating green sheets, the green laminate by laminating a plurality of insulating green sheet Between the laminated body forming step and at least two or more surface conductors to be formed on the surface of the raw laminated body , the raw A recess forming step for forming a recess in the laminated body, and a mask provided with a hole that matches the shape of the planned formation position are aligned with the planned formation position, and a conductive paste is applied through the mask hole. It is characterized by comprising a surface conductor forming step and a firing step of firing the raw laminate to obtain a fired body.
[0013]
The electronic component manufacturing method according to claim 2 of the present invention further includes a recess filling step of filling the recess with an insulating material between the surface conductor forming step and the firing step. It is said.
[0014]
Further, the present invention is characterized in that an electronic component obtained by these manufacturing methods is provided.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
In the following, in describing an embodiment of an electronic component of the present invention, FIG. 1 illustrating a method for manufacturing a multilayer ceramic substrate as an example of an electronic component is for explaining the first embodiment of the present invention. The steps for manufacturing the multilayer ceramic substrate are sequentially shown in a perspective view and a sectional view.
(Green sheet preparation process)
First, a ceramic green sheet which is one of insulating green sheets is prepared. For example, the slurry to be the base is a mixture of powders of barium oxide, silicon oxide, alumina, calcium oxide and boron oxide, an organic vehicle consisting of an organic binder and a solvent and a plasticizer are added and mixed. It is obtained with. A ceramic green sheet can be obtained by forming this slurry on a carrier film into a sheet having a desired thickness by a doctor blade method or the like and drying it.
[0016]
Further, in addition to the one that glass is generated at the time of firing, it may be a composition that can be sintered at a lower temperature by previously containing a sintering aid such as glass, copper oxide, or magnesium oxide. .
[0017]
In addition, an inorganic compound or glass may be added for the purpose of promoting the sintering of the ceramic green sheet, shrinkage behavior control, strength improvement, and electrical property control, or a metal may be added as long as the insulating properties of the substrate are not impaired.
[0018]
A wiring layer pattern and a via hole are formed on the ceramic green sheet thus produced, and a desired number of layers are laminated to produce a raw laminate.
(Recess formation process)
Next, a concave portion is formed in the ceramic sheet on the main surface of the multilayer body by press-contacting a mold between the portions where the surface conductor is to be formed in the surface conductor forming step to be performed later. (A) is a perspective view showing that the mold 13 is in pressure contact with the main surface of the laminate. The shape of the cross section of the recess 12 is not particularly limited, and may be an inverted trapezoidal shape with a long upper side, an inverted triangular shape without a bottom surface, or a rectangular shape as shown in (c). Also, the pressure contact conditions are not particularly limited. For example, when a pressure is applied at a pressure of 100 to 1500 kgf / cm 2 using a mold heated to about 150 ° C., the ceramic is soft enough to form a recess and easy to process. Become.
[0019]
What is important here is that the position where the recess 12 is formed is as close as possible to the position 18 where the surface conductor is to be formed, and the end of the recess 12 is preferably in contact with the end where the surface conductor is scheduled to be formed. .
(Surface conductor formation process)
Next, a surface conductor is formed in the predetermined location 18 on the laminate main surface. In the first embodiment, description will be made assuming that a forming method by printing is used.
[0020]
First, a conductive paste is prepared. The paste is a paste prepared by adding a predetermined amount of an organic vehicle to a conductive powder mainly composed of a metal such as Ag, Au, Cu, Ni, Ag / Pd, Ag / Pt, and stirring and kneading with a raikai machine and three rolls. Use. The organic vehicle is a mixture of a binder resin and a solvent, and ethyl cellulose, acrylic resin, polyvinyl butyral, methacrylic resin, or the like is used as the binder resin. As the solvent, terpineol, butyl carbitol, butyl carbitol acetate, alcohols and the like are used. Moreover, you may add various dispersing agents, a plasticizer, and an activator as needed. Furthermore, a metal oxide such as glass frit or Cu2O, ceramic powder, or resin powder may be added to measure shrinkage matching with ceramic. The paste viscosity may be 50 to 700 Pa · s−1 in consideration of printability.
[0021]
Next, a mask 19 provided with a hole that matches the shape of the surface conductor formation planned location 18 is prepared, the mask 19 is aligned with the formation planned location 18, and the conductive paste prepared through the hole of the mask 19 is prepared. Is applied to form the surface conductor 14. (B) is a perspective view which shows the state of the laminated body main surface before printing, (c) is the cross section which assumed that the mask 19 was aligned with the laminated body of (b), and was cut | disconnected by the AA 'line | wire. FIG. (D) is sectional drawing which shows the state of the AA 'line part after printing.
[0022]
(D) shows that the paste oozes out beyond the range of the two-dot chain line, even though the conductive paste is applied to the size of the planned formation portion 18 shown by the two-dot chain line. ing. However, if the concave portion 12 is formed so that the end portion of the concave portion 12 and the end portion of the planned formation location 18 are close to each other, the bleeding paste 15 drips into the concave portion 12 as shown in FIG. It will be.
[0023]
If there is no recess 12, the surface distance of the ceramic green sheet between the planned formation locations 18 is linear, but by forming the recess 12, the formation planned locations 18 pass through an inclined surface or a bottom surface. It becomes possible to take a longer distance. Therefore, the possibility that the pastes 15 that spread out between the surface conductors are connected to each other can be reduced by increasing the distance.
[0024]
Further, when the mask 19 is separated from the sheet 11 after the printing is finished, if a very small amount of paste is scattered between the surface electrodes, the scattered paste 16 is placed in the recess 12 as shown in FIG. It will adhere.
(Recess filling process)
Next, the filling green sheet 17 formed in advance with a size for filling the concave portion is laminated and pressure-bonded to the concave portion 12. (E) is sectional drawing which showed the state of the laminated body main surface after crimping | compression-bonding. The material of the green sheet for filling is preferably the same as the insulating sheet constituting the substrate body. In this embodiment, the material is preferably the same as the ceramic green sheet 11 produced in the green sheet preparation step. Further, instead of laminating and pressure-bonding the sheet-shaped material, a paste-like ceramic may be screen-printed and filled in the recess 12.
[0025]
By performing this recess filling step, even if the splattering paste 16 adheres to the recesses 12, the splattering paste 16 is buried without being exposed. For this reason, the problem that plating will be coat | covered between surface conductors which may occur when the electroless plating method described in Patent Document 2 is used does not occur.
[0026]
Further, the surface conductor 14 and the filling green sheet 17 are preferably flat without any difference in height. By flattening, adhesion of the metal mask and the substrate is improved when the solder paste is printed using the metal mask when the component parts are mounted, so that solder bleeding can be suppressed.
[0027]
In addition, since the surface conductor of the same size as the intended size is exposed on the substrate by flattening, a substrate with the wiring as designed is produced, and the reliability of the product Will improve.
[0028]
Thereafter, firing is performed at a temperature equal to or higher than the sintering temperature of the ceramic sheet (firing step), and a desired multilayer ceramic substrate is produced. In the case of simultaneous firing with the wiring layer, the temperature is set to be equal to or lower than the melting point of the metal used for the wiring layer.
[0029]
FIG. 2 is for explaining the second embodiment of the present invention, and sequentially shows the steps for manufacturing the multilayer ceramic substrate in cross-sectional views. Descriptions equivalent to those in FIG. 1 are omitted, and elements corresponding to the elements shown in FIG.
[0030]
First, as in the first embodiment, a green sheet preparation step and a recess formation step are performed.
(Transfer preparation process)
In the second embodiment, description will be made assuming that a forming method by transfer is used.
[0031]
First, as in the first embodiment, a conductive paste is prepared, a mask 19 having a hole corresponding to the shape of the surface conductor formation planned portion 18 is prepared, and the mask 19 is disposed on the transfer film 21. Then, the conductive paste prepared through the hole of the mask 19 is applied to form the conductor film 22 on the transfer film 21. (A) is sectional drawing of the film 21 for transfer after printing. As shown in the first embodiment, at the stage of printing on the transfer film 21, the paste oozes out beyond the size to be formed indicated by the two-dot chain line.
[0032]
Further, when the mask 19 is separated from the transfer film 21 after the printing is finished, if a very small amount of paste is scattered between the conductor films 22, the scattered paste 16 adheres on the transfer film 21.
(Surface conductor formation process)
Next, as shown in (b), the transfer film 21 is aligned with the surface conductor formation scheduled portion 18 of the ceramic green sheet 11, and pressed to transfer the conductor film 22 onto the ceramic sheet 11. (C) shows the state after the transfer film 21 is released after the transfer. At this time, the conductor film 22 including the bleeding paste 15 is transferred onto the ceramic green sheet 11 to form the surface conductor 14. However, as in the first embodiment, if the end of the recess 12 is close to the end of the surface conductor formation scheduled portion 18, the bleeding paste 15 is pressed into the recess 12. . As for the scattering paste 16 adhered to the transfer film 21, the size of the scattering paste 16 is very small compared to the depth of the recess 12, and if the pressure bonding does not reach the bottom surface of the recess 12, It remains attached to the transfer film 21 without being transferred to the film. Even if it has been transferred to the concave portion 12, by performing the concave portion filling step, which will be described later, as in the first embodiment, it is embedded including the splatter paste 16, so an unintended solder film is formed. There will be no problems such as
[0033]
Next, similarly to the first embodiment, a recess filling step and a firing step are performed to produce a desired multilayer wiring board.
[0034]
The manufacturing method of the present invention is not limited to the case of forming a surface conductor for mounting component parts. For example, the formation of a surface conductor for connecting a metal wire for wire bonding or the formation of a back surface land for connecting to a mounting board The present invention can be applied to formation, and is not limited to a multilayer ceramic substrate, and can be widely applied to electronic parts in general.
[0035]
【The invention's effect】
As described above, according to the present invention, by forming the surface conductor after providing the recesses between the surface conductors, unintentional connection between the surface conductors can be prevented, and then the recesses are filled by filling the recesses. The paste adhered inside can be embedded, and the surface conductor of the intended size can be formed on the substrate. As a result, an electronic component without a short circuit can be produced even when the surface conductors have a narrow pitch.
[Brief description of the drawings]
1A and 1B are a perspective view and a cross-sectional view of a process for manufacturing a multilayer ceramic substrate for explaining a first embodiment of a method for manufacturing an electronic component of the present invention.
FIG. 2 is a cross-sectional view of a process for manufacturing a multilayer ceramic substrate for explaining a second embodiment of the method for manufacturing an electronic component of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Ceramic green sheet 12 ... Concave 13 ... Mold 14 ... Surface conductor 15 ... Bleeding paste 16 ... Spattering paste 17 ... Filling green sheet 18 ... Place to form 19 ... Mask 21 ... Transfer film 22 ... Conductor film

Claims (3)

A green sheet preparation process for preparing a plurality of insulating green sheets;
A laminate forming step of forming a raw laminate by laminating the plurality of insulating green sheets;
A recess is formed in the raw laminate so as to be close to the end of the planned formation portion between the planned formation locations of at least two or more surface conductors to be formed on the surface of the raw laminate. A recess forming step,
A surface conductor forming step of aligning a mask provided with a hole that matches the shape of the planned formation location with the formation planned location, and applying a conductive paste through the mask hole,
The manufacturing method of an electronic component provided with the baking process of baking the said raw laminated body and obtaining a sintered body. The manufacturing method of the electronic component of Claim 1 further equipped with the recessed part filling process which fills the said recessed part with an insulating material between the said surface conductor formation process and the said baking process. The electronic component produced by the manufacturing method of the electronic component in any one of Claims 1-3.

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