JPH10321455A - Manufacture of chip type electronic part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide various chip type electronic parts in which terminal electrode structures of various chip type electronic parts are made to be in common with one another, a method for manufacturing the chip type electronic part superior in electric characteristics at low cost is realized, and stability of an exterior appearance form of a terminal electrode and protection of an environment by making Pb free are realized. SOLUTION: Electrode paste made by mixing glass frit, organic vehicle and metal powder is applied to both end parts 14 and 15 of a capacitor element 16, and an electrode is formed by baking at a temperature 600-900 deg.C to form a base electrode layer 17, and paste, which comprises Bi salt and Sn or at least one alloy powder selected out of Sn-Ag alloy, Sn-Cu alloy, Sn-Zn alloy, Sn-In alloy, Sn-Ag-Cu alloy, Sn-Ag-In alloy, Sn-Zn-Cu alloy and Sn-Zn-In alloy, is applied on the base electrode layer 17, and then reaction of the Bi salt and the metal is performed at a temperature 200 deg.C or above, thereby an Sn-Bi alloy layer 18 having a thickness 0.1 μm or more is formed to form a terminal electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing various chip-type electronic components used in various electronic devices.

[0002]

2. Description of the Related Art In recent years, with the miniaturization and high performance of small electronic devices such as mobile phones, movies, and notebook computers,
There is a demand for miniaturization and high performance of chip type electronic components used in such small electronic devices.

In order to respond to such needs, current chip-type electronic components have been downsized by forming an electronic component element therein and connecting the lead portion to a terminal electrode. Such a structure is generally used in ceramic electronic components especially among chip electronic components.

[0004] Various chip-type electronic components using the ceramic material as a base material, for example, a single component such as a chip resistor, a chip capacitor, a chip coil, or a composite such as a quartz oscillator, a SAW filter, an LC filter, and an RC network. The terminal electrode of the component is usually a noble metal paste (usually Ag, Ag-P) obtained by kneading a glass frit, a metal powder, and an organic vehicle at a predetermined end of a ceramic base material.
d, etc.) is printed and applied to a thickness of several tens of μm, and then fired at a temperature of 400 to 900 ° C. to form a connection with each functional element portion such as resistance, capacitance, and inductance. I have. Then, since solder erosion occurs at the time of mounting if this electrode layer is used, a Ni layer having excellent solder heat resistance is coated on the electrode layer, and then a solder alloy layer or Sn A layer is formed, and this N
As a method for forming the i-layer, the solder layer, and the Sn layer, an electroplating method is generally used.

FIG. 2 is a cross-sectional view of a square chip resistor as a typical example of a chip type electronic component manufactured by such a conventional method. In FIG. 2, 21 is a 96% alumina substrate, 22 is a pair of upper electrode layers made of an Ag thick film electrode, 23 is a resistance layer made of a ruthenium oxide thick film resistor, 24 is a protective layer made of glass, and 25 is an Ag thick film. Is a side (base) electrode layer, 26 is a Ni plating layer, and 27 is a solder plating layer.

[0006]

However, in recent years,
As one of the environmental protection problems mainly in the United States and European countries, environmental pollution due to lead (Pb) has become a problem, and there is a problem in the above-described structure and manufacturing method. For example, when the product is discarded, Pb contained in the solder plating layer 27 used for the electrode part is eluted by acid rain,
There is a problem that it penetrates underground and contaminates groundwater and the like. In order to solve such a problem, it is necessary to form a terminal electrode without using Pb.
Sn plating has been considered. However, Sn plating has a problem that it is difficult to store it for a long time due to the generation of whiskers. Furthermore, when forming a Sn plating film, a Ni layer and a Sn layer are formed by an electroplating method or an electroless plating method. In the electroless plating method, a plating layer is selectively formed only on an electrode. Since it is difficult to obtain a process such as resist coating, from the viewpoint of cost, adhesion of plating film, and stability,
It is not used in very large-scale production lines.

On the other hand, the electroplating method allows selective plating only on the terminal electrodes. Therefore, the electroplating method is used for the main chip-type electronic components such as square chip resistors and multilayer ceramic capacitors.
Widely used for forming i-layer and solder / Sn layer,
The Sn layer formed by the electroplating method has a problem in moisture resistance because the surface is rough and easily oxidized.

The present invention eliminates the above-mentioned drawbacks of the prior art, is highly reliable, is inexpensive, has excellent mass productivity, and further has the advantage that the electrode is made of P
It is an object of the present invention to provide a chip-type electronic component that realizes environmental protection by making it b-free.

[0009]

In order to solve the above-mentioned problems, a method of manufacturing a chip-type electronic component according to the present invention is directed to an electrode paste obtained by kneading glass frit, an organic vehicle, and metal powder at both ends of an electronic component element. 600-900 ° C
After forming a base electrode by baking at a temperature of the following, after applying a paste made of Bi salt and Sn or Sn alloy on the electrode layer, by reacting Bi salt and metal at a temperature of 200 ℃ or more, Sn-Bi with a thickness of 0.01 μm or more
This is a method in which a terminal electrode is formed by forming a system alloy layer, and it is possible to realize a Pb-free electrode having excellent external shape stability, improved moisture resistance, and excellent solder wettability.

[0010]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, an electrode paste formed by kneading a glass frit, an organic vehicle, and a metal powder is applied to both ends of an electronic component element.
After firing at a temperature of 00 to 900 ° C. to form an electrode, a paste made of Bi salt and at least one metal selected from Sn or Sn alloy is applied on the electrode layer, and then heated to a temperature of 200 ° C. or higher. By performing a reaction between the Bi salt and the metal in the above, a Sn-Bi-based alloy layer having a thickness of 0.01 μm or more is formed to form a terminal electrode, and a base electrode layer to be joined to the ceramic body is By using glass frit and conductive metal powder, it has sufficient adhesion strength to the ceramic body, and is coated with a Sn-Bi alloy film using the reaction of Sn or Sn alloy with Bi. By doing so, it is possible to realize a terminal electrode that has the same appearance and shape stability as a plated product, improved moisture resistance, and excellent solder (Pb-free solder) wettability during product mounting.
This realizes environmental protection by b-free electrodes.

According to a second aspect of the present invention, at least one metal powder or alloy powder of Cu, Ni, or Ag-Pd alloy is used as the electrode paste, and sufficient adhesive strength with the ceramic body is obtained. You can have.

According to a third aspect of the present invention, in the Ag-Pd alloy, the Pd content is set to 10% or more to prevent solder cracking.

According to a fourth aspect of the present invention, the use of a Sn—Ag alloy having an Ag content of 5 wt% or less as a Sn alloy improves moisture resistance and has characteristics equivalent to those of a conventional eutectic solder. In addition, it has the effect of realizing Pb-free environmental protection. Furthermore, since it contains Sn-Ag as a main component, it also has an effect of being excellent in thermal fatigue characteristics.

According to a fifth aspect of the present invention, the use of a Sn—Cu alloy having a Cu content of 1 wt% or less as the Sn alloy improves moisture resistance and has characteristics equivalent to those of a conventional eutectic solder. In addition, it has the effect of realizing Pb-free environmental protection. Furthermore, since Sn-Cu is a main component, it also has an effect of realizing a high melting point Pb-free solder having excellent thermal fatigue characteristics.

According to a sixth aspect of the present invention, the use of a Sn—Zn alloy having a Zn content of 15 wt% or less as a Sn alloy improves moisture resistance and has characteristics equivalent to those of a conventional eutectic solder. In addition, it has the effect of realizing Pb-free environmental protection. Furthermore, since Sn-Zn is a main component, it has an effect of being excellent in mechanical properties.

According to a seventh aspect of the present invention, the use of a Sn—In alloy having an In content of 52 wt% or less as a Sn alloy improves moisture resistance and has characteristics equivalent to those of a conventional eutectic solder. In addition, it has the effect of realizing Pb-free environmental protection. Further, Pb due to the addition of In
It has the effect of lowering the melting point of free solder.

According to the present invention, the Sn alloy has an Ag content of 5 wt% or less and a Cu content of 1 wt%.
The use of the following Sn-Ag-Cu alloy improves moisture resistance, has the same characteristics as conventional eutectic solder, and has the effect of realizing Pb-free environmental protection. Furthermore, it has the effect of being excellent in thermal fatigue characteristics and having very little change over time.

According to a ninth aspect of the present invention, the Sn alloy has an Ag content of 5 wt% or less and a Zn content of 30 wt%.
% Or less of Sn-Ag-Zn alloy improves moisture resistance and has the same characteristics as conventional eutectic solder.
Moreover, it has an effect of realizing environmental protection by Pb-free. Further, it has an effect of being excellent in thermal fatigue properties and mechanical properties.

According to a tenth aspect of the present invention, the Sn alloy has an Ag content of 5 wt% or less and an In content of 30 wt%.
% Of Sn-Ag-In alloy is used to improve the moisture resistance and have the same characteristics as the conventional eutectic solder.
Moreover, it has an effect of realizing environmental protection by Pb-free. Further, it has the effect of lowering the melting point by adding In and having excellent thermal fatigue characteristics.

[0020] According to the present invention, the Sn alloy has a Cu content of 1 wt% or less and a Zn content of 15 wt% or less.
% Of Sn-Cu-Zn alloy improves moisture resistance and has the same characteristics as conventional eutectic solder.
Moreover, it has an effect of realizing environmental protection by Pb-free. Further, it has the effect of realizing a high melting point Pb-free solder having excellent thermal fatigue properties and mechanical properties.

According to a twelfth aspect of the present invention, the Sn alloy has a Cu content of 1 wt% or less and an In content of 30 wt%.
%, The use of the Sn-Cu-In alloy at the same level or less has the same effect as the ninth aspect of the present invention.

According to a thirteenth aspect of the present invention, the Sn alloy has a Zn content of 15 wt% or less and an In content of 30 w%.
By using an Sn-Zn-In alloy of t% or less,
It has improved moisture resistance, has the same characteristics as conventional eutectic solders, and has the effect of realizing Pb-free environmental protection. Further, it has the effect of lowering the melting point by adding In and having excellent mechanical properties.

Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a multilayer ceramic capacitor as a chip-type electronic component showing an embodiment of the present invention. Hereinafter, a method for manufacturing a multilayer ceramic capacitor will be described with reference to FIG.

Using a dielectric material mainly composed of barium titanate, several μm to several tens μm by a doctor blade method.
The green sheet 11 is formed with a thickness of m. An internal electrode 12 is formed on the surface of the green sheet 11 by a screen printing method using an electrode paste mainly composed of palladium. Next, the dielectric sheet 1 on which the internal electrodes 12 are formed
3 are laminated in such a manner that the internal electrodes 12 extend from both ends 14 and 15, and cut into individual pieces each having a capacitor element size.

Next, the internal electrodes 12 of the capacitor element 16 formed by firing at a temperature of 100 to 1400 ° C. are exposed at both ends 14 and 15 by a method such as barrel polishing.
It is electrically connected to external electrodes.

Specifically, glass frit, vehicle,
A paste composed of Cu powder is applied to both end portions 14 and 15 of the capacitor element 16. Thereafter, the resultant was baked at 900 ° C. to form a base electrode layer 17. Next, the Bi content was 10 wt.
% Bi salt paste and a Sn-Ag eutectic alloy powder in a weight ratio of 1: 2, and then applied at 220 ° C.
Heat treatment was performed for 5 minutes. By this processing, B
Substitution occurs due to the difference in ionization tendency between the Bi ion and Sn in the i-salt, and the precipitated Bi diffuses into the Sn-Ag powder, so that Sn (95) -Ag (3.5) -Bi
The ternary alloy film of (5) was obtained.

According to the same method, Sn-Cu eutectic alloy powder, Sn-Zn eutectic alloy powder, Sn-In (10)
Alloy powder, Sn-Ag (3.5) -Cu (0.7) alloy powder, Sn-Ag (3.5) -Zn (9) alloy powder, Sn-
Ag (3.5) -In (10) alloy powder, Sn-Cu
(0.7) -Zn (9) alloy powder, Sn-Cu (0.7)
-In (10) alloy powder, Sn-Zn (9) -In (1
0) Heat treatment is performed by mixing the alloy powders and Sn-
Bi (5) -Cu (0.7) alloy film, Sn-Bi (5)
-Zn (9) alloy film, Sn-Bi (5) -In (10)
Alloy film, Sn-Ag (3.5) -Bi (5) -Cn
(0.7) Alloy film, Sn-Ag (3.5) -Bi (5)
-Zn (9) alloy film, Sn-Ag (3.5) -Bi
(5) -In (10) alloy film, Sn-Bi (5) -Cu
(0.7) -Zn (9) alloy film, Sn-Bi (5) -C
u (0.7) -In (10) alloy film, Sn-Bi (5)
A -Zn (9) -In (10) alloy film was obtained.

In the present embodiment, the composition ratio of the Bi salt paste and the metal powder is set to 1: 2. However, by changing the composition ratio, the composition of the alloy film can be changed and the Bi salt content can be changed. By changing the composition of the Bi and Sn alloy powders, Sn-Bi of various compositions can be obtained.
Needless to say, a system alloy film can be obtained.

In forming an alloy film, it is necessary that the melting point is equivalent to that of a conventional eutectic solder (mp 183 ° C.).
g content is 5 wt% or less, Cu content is 1 wt% or less,
Zn content is 15 wt% or less, In content is 30 wt%
The following Sn alloy is desirable.

The reason why Bi and Sn are substituted is that P
This is because Sn is the only main component that can be considered as a substitute material for b, and Bi is not considered as a low melting point material that can be substituted with Sn.

In this embodiment, an electrode mainly composed of Cu is used as the base electrode. However, in the case of Cu, solder erosion occurs. Therefore, it is desirable that the electrode thickness is as large as possible.

On the other hand, when Ni is used, since the solder is not eroded, the electrode can be formed thinner, so that a more excellent electrode can be formed.

Table 1 shows the results of mounting the multilayer ceramic capacitor manufactured by the above method and evaluating the conventional solder plating and Sn plating as comparative samples.
From these results, characteristics similar to or better than those of conventional solder plating and Sn plating products were obtained in solder wettability and moisture resistance.

[0035]

[Table 1]

As described above, the Sn—Ag—Bi alloy layer formed by the method of the present embodiment is excellent in mass productivity because it is not subjected to resist treatment unlike electroless plating. In addition, since the surface of the terminal electrode is covered with a very dense alloy film, the terminal electrode has excellent moisture resistance as compared with the Sn plating layer, and has the same appearance and shape stability as a plated product, and also has a solder wettability during mounting. It also has the characteristic of having excellent properties. Furthermore, since it is formed of an alloy film not using Pb, environmental protection can be realized.

In the present embodiment, Sn-Ag-Bi alloy film, Sn-Bi-Cu alloy film, Sn-Bi-Zn alloy film, Sn-Bi-In alloy film, Sn-Ag- Bi-Cu alloy film, Sn-Ag-Bi
-Zn alloy film, Sn-Ag-Bi-In alloy film, Sn-
A Bi—Cu—Zn alloy film, a Sn—Bi—Cu—In alloy film, and a Sn—Bi—In—Zn alloy film were formed.
It is needless to say that a similar effect can be obtained also with an alloy film having as a main component and having a melting point of 180 to 230 ° C.

(Embodiment 2) Next, the insulated 35
After winding a μmφ copper wire around a 1mmφ ferrite bobbin to the desired number of turns, the structure is based on a structure in which the ends of the copper wire are exposed on a pair of end surfaces of a chip coil injection-molded with epoxy resin. Next, as a preparation step for forming a base electrode, a portion of the molded body where a terminal electrode is to be formed is exposed. The exposed terminal electrode was formed in the same manner as in the first and second embodiments, in the order of the base electrode and the Sn—Bi-based alloy layer 18.

In the structure of a chip-type electronic component having a structure in which a terminal is formed by cutting a copper wire as described above, the terminal electrode is formed by the terminal electrode structure and the manufacturing method of the present invention. It was confirmed that it was possible.

[0040]

As is apparent from the above description, according to the present invention, the base electrode is composed of the conductive metal powder and the glass frit, and the Sn-Bi alloy is formed by the substitution reaction between the Bi salt and Sn or the Sn alloy. By forming the layer, it is possible to obtain a terminal electrode having excellent adhesive strength, excellent appearance shape comparable to a plated product and excellent solder wettability, and dramatically improving the quality of chip-type electronic components, Cost reduction is also possible.

Further, as described in each of the embodiments, this method enables the terminal structure of various chip-type electronic components to be configured with a common structure and a manufacturing line, so that equipment costs are reduced. , And the material can be used in common.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of a multilayer capacitor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the structure of a conventional square chip resistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Green sheet 12 Internal electrode 13 Dielectric sheet 14, 15 Both ends 16 Capacitor element 17 Base electrode layer 18 Sn-Bi alloy layer 21 96% alumina substrate 22 Top electrode layer 23 Resistive layer 24 Protective layer 25 Side electrode layer 26 Ni Plating layer 27 Solder plating layer

Claims (13)

[Claims] An electrode paste formed by kneading a glass frit, an organic vehicle, and a metal powder is applied to both ends of an electronic component element and fired at a temperature of 600 to 900 ° C. to form an electrode. After applying a paste made of Bi salt and Sn or Sn alloy thereon, a reaction between the Bi salt and the metal is performed at a temperature of 200 ° C. or more to form a Sn—Bi-based alloy layer having a thickness of 0.01 μm or more. A method for manufacturing a chip-type electronic component in which a terminal electrode is formed. 2. An electrode paste comprising Cu, Ni, Ag-
The method for manufacturing a chip-type electronic component according to claim 1, wherein at least one metal powder or alloy powder among Pd alloys is used. 3. An Ag—Pd alloy having a Pd content of 1
The method for producing a chip-type electronic component according to claim 2, wherein the content is 0% or more. 4. The Sn alloy has an Ag content of 5 wt%.
The method for manufacturing a chip-type electronic component according to claim 1, wherein the following Sn-Ag alloy is used. 5. The Sn alloy has a Cu content of 1 wt%.
The method for manufacturing a chip-type electronic component according to claim 1, wherein the following Sn-Cu alloy is used. 6. The Sn alloy has a Zn content of 15 wt.
2. The method for manufacturing a chip-type electronic component according to claim 1, wherein the Sn-Zn alloy is used in an amount of not more than 5%. 7. The Sn alloy has an In content of 30 wt.
The method for manufacturing a chip-type electronic component according to claim 1, wherein the Sn-In alloy is used in an amount of not more than 5%. 8. The Sn alloy has an Ag content of 5 wt%.
2. The method for manufacturing a chip-type electronic component according to claim 1, wherein a Sn-Ag-Cu alloy having a Cu content of 1 wt% or less is used. 9. The Sn alloy has an Ag content of 5 wt%.
Hereinafter, Sn-Ag-Zn having a Zn content of 15 wt% or less.
The method for manufacturing a chip-type electronic component according to claim 1, wherein an alloy is used. 10. An Sn alloy having an Ag content of 5 wt.
% Or less, and the In content is 30 wt% or less.
The method for manufacturing a chip-type electronic component according to claim 1, wherein an n-alloy is used. 11. The Sn alloy has a Cu content of 1 wt.
% Or less, and Sn-Cu-Z having a Zn content of 15% by weight or less.
The method for manufacturing a chip-type electronic component according to claim 1, wherein an n-alloy is used. 12. The Sn alloy has a Cu content of 1 wt.
% Or less, Sn-Cu-I having an In content of 30% by weight or less.
The method for manufacturing a chip-type electronic component according to claim 1, wherein an n-alloy is used. 13. The Sn alloy has a Zn content of 15 watts.
t-% or less, and the In content is 30 wt% or less.
The method for manufacturing a chip-type electronic component according to claim 1, wherein an In alloy is used.