JP3331566B2 - Method for forming terminal electrodes of chip-type electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming terminal electrodes of chip-type electronic components such as chip capacitors, chip inductors, chip resistors, and chip thermistors. More specifically, the present invention relates to a method of performing a pre-plating treatment after forming a base electrode constituting a terminal electrode of a chip-type electronic component.

[0002]

2. Description of the Related Art As shown in FIG. 1, a conventional chip-type electronic component of this kind, for example, a multilayer ceramic capacitor 10 has a bare chip 11 made of a ceramic dielectric and a base electrode 12 formed on both opposite ends thereof. And the underlying electrode 1
2, the base electrode 12 and the plating layers 14, 15 form terminal electrodes. A pair of base electrodes 12 are provided inside the bare chip 11.
Are provided with internal electrodes 13 electrically connected alternately.
The base electrode 12 is coated with a conductive paste made by kneading a metal powder, a glass frit, and an inert organic vehicle on both ends of the bare chip 11, dried, and then subjected to 600 to 85.
It is formed by firing at a temperature of about 0 ° C. The plating layers 14 and 15 are formed by coating the bare chip 11 on which the base electrode 12 is formed with Ni by electrolytic barrel plating or electroless plating.
It is formed by dipping in a plating solution containing Cu, Sn, Sn / Pb alloy and the like. The multilayer ceramic capacitor 10 having such a structure is used by soldering its terminal electrodes to a predetermined substrate.

[0003]

Generally, a base electrode which becomes a sintered body by firing a conductive paste has many pores when observed microscopically. For this reason, when the bare chip is immersed in the plating solution, the plating solution enters the pores of the base electrode and is captured. When soldering the terminal electrodes of such a multilayer ceramic capacitor to a predetermined substrate, the plating solution captured in the pores may boil and evaporate. In this case, a gap is formed at the interface between the base electrode and the bare chip, and the conductivity of the base electrode with respect to the internal electrode is deteriorated. When the gap is increased, a crack 16 is formed as shown in FIG. Is peeled off from the bare chip 11. An object of the present invention is to form a terminal electrode of a chip-type electronic component that does not peel off from a bare chip when a terminal electrode composed of a base electrode and a plating layer of the chip-type electronic component is soldered to a predetermined substrate. It is to provide a method.

[0004]

Means for Solving the Problems In order to achieve the above object, the configuration of the present invention will be described with reference to FIG. According to the present invention, a pair of base electrodes 12 are formed by applying and baking a conductive paste to opposite ends of a bare chip 11 made of a ceramic material, and the surfaces of the base electrodes 12 are plated. This is an improvement in the method of forming the terminal electrodes of the chip-type electronic component by forming 14 and 15. The characteristic configuration is that the bare chip 1 is formed after the base electrode 12 is formed and before the plating layers 14 and 15 are formed.
1 is immersed in an oil compatible with an organic solvent and pressurized.

In the present invention, the oil has a boiling point of at least 1
00 ° C. and 60 to 90 when the bare chip 11 is immersed.
Desirably, it is maintained in the range of ° C. This is because the oil quickly enters the pores of the base electrode. For this purpose, the oil is preferably silicone oil, alkyd resin-based oil, fluororesin-based oil, or the like. In particular, silicone oil is preferable because it is easily available and easy to handle. Also, a bare chip 11 immersed in oil to facilitate formation of a plating layer
It is desirable to remove the oil adhering to the surface of the base electrode with an organic solvent after extracting the oil from the oil. For this reason, the oil needs to be compatible with the organic solvent. Examples of the chip-type electronic component include a chip capacitor, a chip inductor, a chip resistor, and a chip thermistor.

[0006]

After forming the base electrode 12, the plating layers 14, 1
If the bare chip 11 is immersed in an oil compatible with an organic solvent and pressurized before forming 5, the oil enters the pores of the base electrode 12. Even if the base electrode is washed with an organic solvent to form a plating layer, the organic solvent does not remove the oil that has entered the pores. Even if the plating solution attempts to enter the pores during plating, the plating solution cannot enter because the pores are filled with oil.

[0007]

As described above, according to the present invention, since the pores of the base electrode are filled with oil before forming the plating layer, even if the base electrode is immersed in a plating solution, The liquid cannot enter the pores of the base electrode. With this, when the terminal electrode composed of the base electrode and the plating layer of the chip-type electronic component is soldered to a predetermined substrate, the plating solution does not exist in the pores of the base electrode. The terminal electrode does not peel off from the bare chip without generating a crack.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings together with comparative examples. <Embodiment 1> As shown in FIG. 1, the chip type electronic component is a chip type multilayer ceramic capacitor 10 in this example. In order to manufacture this capacitor 10, as shown in FIG. 2, first, an internal electrode 1 made of Ag70 / Pd30 is used.
3, length 3.2 mm, width 1.6 mm, thickness 0.8
A 5 mm lead perovskite-based bare chip 11 was prepared.

As shown in FIG. 3, a base electrode 12 was formed under the following conditions. When the conductive paste is 100% by weight, 75% by weight of metal powder and 1
A conductive paste was prepared by kneading 0% by weight of a glass frit and the remainder being an inert organic vehicle. Here, the metal powder is composed of 100% by weight of Ag, and the glass frit is P
bO (30 _{wt%) - B 2 O 3 (} 30 wt%) - SiO ₂
(40% by weight). The organic vehicle used was a mixture of ethyl cellulose and butyl carbitol and terpineol. The thickness after baking this paste is 9
It was applied to both ends of the bare chip 11 by a dip method so as to have a thickness of 0 μm, and dried at 150 ° C. for 10 minutes under atmospheric pressure. The temperature of the bare chip 11 was raised to 750 ° C. under the atmospheric pressure at a rate of 25 ° C./min.
The temperature was lowered to room temperature at a rate of ° C./min to obtain a base electrode 12 made of Ag.

The bare chip 11 on which the base electrode 12 is formed is immersed in a silicone oil heated to 80 ° C., and a pressure of 3 kg / cm ² is applied for 5 minutes using an isostatic press. The pores of the base electrode 12 were filled with silicone oil. The pressure-treated bare chip 11 was pulled out of the silicone oil and immersed in toluene compatible with the silicone oil. Here, ultrasonic cleaning was performed for 3 minutes to remove excess silicone oil adhering to the surface of the base electrode 12. Thereafter, the bare chip 11 pulled up from the toluene was dried at 60 to 150 ° C.

On the surface of the base electrode 12 treated with the silicone oil, a Ni plating layer 14 and Sn / Pb
(Solder) plating layers 15 were sequentially formed under the following conditions. Using a bath having a composition of 120 g / L of nickel sulfamate having a pH of 4.0 and a temperature of 25 ° C., a Ni plating layer 14 having a thickness of 2 μm was formed on the surface of the base electrode 12 by electrolytic barrel plating. tin (Sn) and lead (P) at a pH of 4.0 and a temperature of 25 ° C.
b) Using a bath having a composition of 9: 1, the Sn / Pb plating layer 1 having a thickness of 6 μm was formed on the surface of the Ni plating layer by electrolytic barrel plating.
5 was formed. As a result, an additional 2
Ceramic Capacitor 10 with Multiple Plating Layers
I got The Ni plating layer 14 prevents electrode erosion due to solder when soldering the multilayer ceramic capacitor 10 to a substrate, and the Sn / Pb plating layer 15 facilitates soldering.

Example 2 A multilayer ceramic capacitor was obtained in the same manner as in Example 1 except that the pressure applied by the isotropic isostatic press was set to 10 kg / cm ² .

<Embodiment 3> The pressure applied by an isotropic hydrostatic press is 30 kg / cm ² , and the pressing time is 1
A multilayer ceramic capacitor was obtained in the same manner as in Example 1, except that the time for ultrasonic cleaning in toluene was set to 5 minutes, and the time for ultrasonic cleaning in toluene was set to 5 minutes.

<Embodiment 4> The pressure applied by an isotropic hydrostatic press is 50 kg / cm ² , and the pressing time is 2
A multilayer ceramic capacitor was obtained in the same manner as in Example 1, except that the time for the ultrasonic cleaning in toluene and the time for the ultrasonic cleaning in toluene were set to 5 minutes.

<Embodiment 5> The pressure applied by an isotropic isostatic press is 80 kg / cm ² , and the pressing time is 2 kg / cm ² .
A multilayer ceramic capacitor was obtained in the same manner as in Example 1, except that the ultrasonic cleaning time in toluene for 10 minutes was changed to 10 minutes.

Example 6 Except that the pressure applied by an isotropic isostatic press was 100 kg / cm ² , the pressurizing time was 1 minute, and the ultrasonic cleaning time in toluene was 60 minutes. In the same manner as in Example 1, a multilayer ceramic capacitor was obtained.

Example 7 Except that the pressure applied by an isotropic isostatic press was 200 kg / cm ² , the pressurizing time was 1 minute, and the ultrasonic cleaning time in toluene was 2 minutes. In the same manner as in Example 1, a multilayer ceramic capacitor was obtained.

Example 8 Except that the pressure applied by an isotropic isostatic press was 300 kg / cm ² , the pressurizing time was 3 minutes, and the ultrasonic cleaning time in toluene was 15 minutes. In the same manner as in Example 1, a multilayer ceramic capacitor was obtained.

Example 9 Except that the pressure applied by an isotropic isostatic press was 500 kg / cm ² , the pressurizing time was 1 minute, and the ultrasonic cleaning time in toluene was 30 minutes. In the same manner as in Example 1, a multilayer ceramic capacitor was obtained.

Comparative Example 1 A multilayer ceramic capacitor was obtained in the same manner as in Example 1 except that the bare chip 11 on which the base electrode 12 was formed was not impregnated with silicone oil.

<Measurement and Evaluation> The multilayer ceramic capacitors produced in Examples 1 to 9 and Comparative Example 1 were gripped with tweezers, immersed in a solder bath maintained at 400 ° C. for 3 seconds, and then pulled up. Whether or not the terminal electrode was separated from the bare chip was determined by measuring the capacitance value of the multilayer ceramic capacitor before and after immersion in the solder bath.
Table 1 shows the results. In Table 1, the numerical value n is the number of samples tested.

[0022]

[Table 1]

As is clear from Table 1, Example 1 of the present invention
Regarding the multilayer ceramic capacitors obtained by the methods of Nos. 9 to 9, the sample whose capacitance value was reduced under any of the conditions of impregnation with silicone oil was zero, and there was no inconvenience that the terminal electrode was peeled off from the bare chip. On the other hand, with respect to the multilayer ceramic capacitor of Comparative Example 1 which was not impregnated with the silicone oil under pressure, the capacitance value of 78 out of 100 tested samples was reduced, and the terminal electrode was bare chipped at a high rate. It was found that the film had peeled off.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor.

FIG. 2 is a cross-sectional view of a bare chip before forming a base electrode.

FIG. 3 is a cross-sectional view of the bare chip after the base electrode is formed.

FIG. 4 is a cross-sectional view showing a state in which terminal electrodes of a conventional multilayer ceramic capacitor are separated from a bare chip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Multilayer ceramic capacitor 11 Bare chip 12 Base electrode 13 Internal electrode 14, 15 Plating layer

Claims (4)

(57) [Claims] 1. A bare chip (11) made of a ceramic material.
A conductive paste is applied to the opposite ends of the substrate and baked to form a base electrode (12), and a plating layer (14, 15) is formed by plating the surface of the base electrode (12) to form a chip. In the method of forming a terminal electrode of a die-type electronic component, after forming the base electrode (12) and before forming a plating layer (14, 15), the bare chip (11) is mixed with an organic solvent compatible oil. A method for forming a terminal electrode of a chip-type electronic component, wherein the terminal electrode is immersed and pressed. 2. The method according to claim 1, wherein the oil has a boiling point of at least 100 ° C., and the oil is maintained in the range of 60 to 90 ° C. when the bare chip (11) is immersed. 3. The method according to claim 2, wherein the oil is a silicone oil. 4. The terminal electrode of a chip-type electronic component according to claim 1, wherein after removing the bare chip (11) immersed in the oil from the oil, the oil adhering to the surface of the base electrode (12) is removed with an organic solvent. Forming method.