JP4423892B2 - Manufacturing method of electronic parts - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an electronic component, and more particularly, to a method for manufacturing an electronic component including an external electrode at an end of a ceramic body containing a circuit element.
[0002]
[Prior art]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-60530
As a method of forming external electrodes on both ends of a ceramic body containing circuit elements, the end of the body is immersed in a conductive paste film uniformly applied to a predetermined thickness on a base board. A method is known in which the conductive paste is pulled up and attached to the end, followed by drying and baking.
[0004]
FIG. 9 is a graph showing a conventional immersion profile when the end of the electronic component body is immersed in the conductive paste film. The vertical axis indicates the distance from the surface of the conductive paste film to the lower end face of the element body, and the horizontal axis indicates the elapsed time.
[0005]
As shown in FIG. 9, conventionally, the element body is immersed in a conductive paste at a descending speed V1 (for example, 10 mm / s), and stops for a certain time (for example, T seconds, for example, 3 seconds) when reaching the bottom dead center H0. After that, the substrate is pulled up relatively slowly at a rising speed V3 (for example, 1 mm / s), and when the end face of the element body is completely separated from the conductive paste film, the speed is switched to the speed V4 (for example, 10 mm / s) to increase the speed. It was raised.
[0006]
By the way, the external electrode 2 formed by the conventional immersion profile shown in FIG. 9 has a shape (hereinafter referred to as the following) that gently spreads in the center so as to draw an arc along the surface of the element body 1 as shown in FIG. It was sometimes referred to as a crescent moon shape).
[0007]
As described above, there are mainly two reasons why the boundary portion between the external electrode 2 and the element body 1 has a crescent shape.
[0008]
(1) After the element body 1 is immersed in the conductive paste film, the surface of the conductive paste film is crescent shaped along the surface of the element body 1 by the surface tension while being held at the bottom dead center H0 for a certain period of time. Get wet.
[0009]
(2) After the element body 1 is pulled up from the conductive paste film, the conductive paste attached to the end of the element body 1 tends to become spherical due to its own surface tension. A crescent shape rises along the surface. This phenomenon becomes more prominent as the amount of conductive paste attached to the end of the element body 1 increases.
[0010]
The above-mentioned crescent shape of the external electrode 2 varies the dimension A between the external electrodes 2 and causes a short circuit failure between the external electrodes 2 due to a decrease in withstand voltage, reflow soldering, and poor adhesion to the printed circuit board. Has led to a decline. Incidentally, in FIG. 10, L is the folded dimension of the external electrode 2, and D is the crescent amount.
[0011]
Therefore, as a countermeasure against this, in Patent Document 1, before applying the conductive paste to the end of the element body, a preheating drying process is performed at a temperature that makes the surface of the element body sparse, A method for removing residual solvent and adhering moisture is described. After this preheating and drying treatment, the boundary portion between the element body and the conductive paste can be made linear by applying the conductive paste while keeping the temperature maintained.
[0012]
[Problems to be solved by the invention]
However, in the method described in Patent Document 1, since the preheating drying temperature of the element body is as high as about 100 ° C., the conductivity applied to the end of the element body while being immersed in the conductive paste film. Drying of the adhesive paste proceeds. For this reason, although the crescent moon shape generated at the boundary portion between the element body and the conductive paste is suppressed, the amount of the conductive paste adhering to the end face and the peripheral surface of the element body increases. As a result, the external electrode has a rounded shape that bulges outward, and problems are likely to occur during reflow soldering.
[0013]
Further, it is conceivable to improve the immersion profile shown in FIG. 9 and shorten the immersion time as much as possible. However, in recent years, as the size of the element body 1 is reduced, the folded dimension L of the external electrode 2 is reduced, and it is difficult to suppress the crescent amount D only by improving the immersion profile.
[0014]
Accordingly, an object of the present invention is to provide a method of manufacturing an electronic component that can effectively suppress the crescent shape of the external electrode generated at the boundary portion between the element body and the external electrode, even if the element body has a small size. There is.
[0015]
[Means and Actions for Solving the Problems]
In order to achieve the above object, a method of manufacturing an electronic component according to the present invention provides a conductive paste film that lowers an element body of an electronic component and maintains an end surface portion of the element body to a predetermined reference surface. A step of immersing, a step of raising the element body and pulling up the end face portion from the conductive paste film, and applying a conductive paste to the end face portion; and an end face portion of the element body on the conductive paste film A step of lowering the reference surface of the conductive paste film until the end surface portion is pulled up from the surface of the conductive paste film after the immersion, and the end surface of the element body is lowered to the bottom dead center. At the time, when the rising of the element is temporarily stopped while the end face portion of the element is immersed in the conductive paste film, or when the end face of the element is lowered to the bottom dead center. Once the element is stopped, Reducing the reference surface of the conductive paste films either, it characterized.
[0016]
In the method for manufacturing an electronic component according to the present invention, after the end face portion of the element body is immersed in the conductive paste film, the end face portion is lifted from the surface of the conductive paste film, and the reference of the conductive paste film is obtained. In order to lower the surface, the force to lower the reference surface acts in the direction opposite to the wetting force of the conductive paste attached to the end face portion of the element body, and the crescent moon shape becomes smaller.
[0017]
That is, in order to prevent the conductive paste adhering to the end face portion of the element body from getting wet into a crescent shape, the conductive paste adhering to the element body is applied with the wetting force of the conductive paste adhering to the element body. It is sufficient to make it smaller than the force obtained by adding the tensile force from the conductive paste film to its own weight. In the manufacturing method according to the present invention, a force for reducing the reference surface of the conductive paste film is further applied, and the wetting of the conductive paste is further suppressed.
[0018]
Step to reduce the reference surface of the conductive paste films as possible out to perform by suction means provided on the lower surface of the conductive paste films.
[0019]
When the conductive paste film is sucked by the suction means, the conductive paste film is formed on the base board having a large number of suction holes so as to have a predetermined thickness, and is sucked from the suction holes so that the reference It is preferable that the surface is lowered . In order to form the conductive paste film with a predetermined thickness on the base board, the conductive paste extruded from the suction hole onto the base board may be formed with a squeegee.
[0020]
In order to efficiently suck the conductive paste film, the suction holes are uniformly distributed on the base board, and it is preferable that the plurality of suction holes face the end face of the element body. Moreover, it is preferable that a suction hole opposes the peripheral part of the end surface of an element | base_body.
[0021]
In the manufacturing method according to the present invention, the end surface of the element body is preferably lowered to the surface of the base board. The immersion depth of the element body varies depending on the dimensional error of the element itself, the error of the holder holding the element body, and the mounting error. If the end face of the element body is lowered to the surface of the base board, the immersion depth of the element body can be made constant regardless of this kind of error.
[0022]
Also, the element body may be lifted after being immersed in the conductive paste film immediately after the end face of the element body is lowered to the bottom dead center, or the end face of the element body is lowered to the bottom dead center. Immediately after, the element is raised at a first speed, and the rising of the element is temporarily stopped until the end face rises to the reference surface of the conductive paste film, and then the element is moved at a second speed. It may be raised. Alternatively, immediately after the end face of the element body is lowered to the bottom dead center, the element body is raised at the first speed, and the element body is raised at the second speed until the end face exceeds the reference plane of the conductive paste film. Thereafter, the element body may be raised at a third speed. The first speed is preferably higher than the second speed.
[0023]
The timing of starting the suction of the conductive paste film may be when the end face of the element body is lowered to the bottom dead center, or may be when the ascent of the element body is once stopped. Further, when the end face of the element body is lowered to the bottom dead center, the element body may be temporarily stopped and suction of the conductive paste film may be started.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an electronic component manufacturing method according to the present invention will be described below with reference to the accompanying drawings.
[0025]
(External electrode formation process, see FIG. 1)
1A to 1D show an example of a process for forming an external electrode 2 on an end face portion 1a of an element body 1 of a ceramic electronic component. Examples of the ceramic electronic component include a multilayer ceramic capacitor, a resistor inductor, a multilayer ceramic LC filter, and a thermistor. In this step, the base board 10 provided with the suction holes 11 is used. The suction holes 11 have a predetermined diameter (for example, 0.1 to 0.2 mm) and are formed at a predetermined pitch (for example, 0.2 to 0.3 mm).
[0026]
First, as shown in FIG. 1A, the conductive paste film 22 is pushed out from the suction hole 11 onto the base board 10, and the squeegee 5 is moved in the horizontal direction so that the surface of the paste film 2 has a predetermined thickness h. Let me know. The predetermined thickness h is set corresponding to the folding dimension L of the external electrode 2 (see FIG. 1D). The conductive paste film 22 includes a conductive metal such as Ag, Ag—Pd, or Cu as a main component and a glass frit, a resin binder, a solvent, and the like.
[0027]
Next, the element body 1 held by the holder 6 is lowered and its end face is lowered to the surface of the base board 10 and immersed in the conductive paste film 22 (see FIG. 1B). Here, the conductive paste adheres to the end face portion 1 a of the element body 1.
[0028]
Next, the element body 1 starts to rise, and the conductive paste film 22 is sucked from the suction hole 11. Thus, the conductive paste film 22 is removed from the base board 10 (FIG. 1C). When the end face portion 1a of the element body 1 is sufficiently separated from the surface of the base board 10, the conductive paste film 22 is again pushed out from the suction hole 11 onto the base board 10 (see FIG. 1D), and the next element body is applied. Prepare for the formation of external electrodes.
[0029]
According to the external electrode forming process described above, since the conductive paste film 22 is sucked from the base board 10 after the end surface portion 1a of the base body 1 is immersed in the conductive paste film 22, the suction force is generated. 1 acts in a direction opposite to the wetting force of the conductive paste adhered to the end face portion 1a, and the crescent shape is reduced.
[0030]
That is, in order to prevent the conductive paste adhering to the end face portion of the element body 1 from being wetted into a crescent shape, the wetting of the conductive paste adhering to the element body 1 as shown in FIG. The rising force F1 may be made smaller than the force obtained by adding the tensile force F2 from the conductive paste film 22 to the self-weight of the conductive paste attached to the element body 1. In this step, the conductive paste is further reduced. A force F3 for sucking the film 22 acts, and the wetting of the conductive paste is further suppressed.
[0031]
Note that the immersion profile of the element body 1 and the timing of sucking the conductive paste film 22 have various modes described below with reference to FIGS. 2 to 5, and may be other modes. Further, the bottom dead center of the element body 1 is not the surface of the base board 10 but may be a position slightly away from the surface. However, the end face of the element body 1 is preferably lowered to the surface of the base board 10. The immersion depth of the element body 1 varies depending on the dimensional error of the element body 1 itself, the error of the holder 6 that holds the element body, and the mounting error. This is because if the end face of the element body 1 is lowered to the surface of the base board 10, the immersion depth of the element body 1 can be made constant regardless of this type of error.
[0032]
(Immersion profile and suction timing, see FIGS. 2 to 5)
Here, the first to fourth examples will be described with respect to the immersion profile of the element body 1 and the suction timing of the conductive paste film.
[0033]
In the first example, as shown in FIG. 2, first, the surface of the conductive paste film 22 is squeezed so as to have a predetermined height h, and then the element body 1 is moved to a speed V1 (for example, 10 to 30 mm / s). To lower. This height h is defined as a reference plane H1. As soon as the end face of the base body 1 reaches the surface of the base board 10, the base body 1 is immediately raised at a first speed V2 (for example, 1 to 25 mm / s) and suction of the conductive paste film 22 is started. .
[0034]
Then, the rising of the element body 1 is temporarily stopped (for example, within 10 seconds, preferably within 5 seconds) until the end face of the element body 1 rises to the reference plane H1. Thereafter, the element body 1 is raised at a second speed V3 (for example, 0.05 to 1 mm / s). When the end surface of the element body 1 is completely separated from the reference plane H1, the third speed V4 (for example, 10 to 10 mm) is obtained. 30 mm / s). The first speed V2 is faster than the second speed V3.
[0035]
In the second example, as shown in FIG. 3, the immersion profile of the element body 1 is the same as that of the first example. The difference is that the timing at which the suction of the conductive paste film 22 is started is set at a point where the rise of the element body 1 is temporarily stopped.
[0036]
In the third example, as shown in FIG. 4, first, the surface of the conductive paste film 22 is squeezed so as to have a predetermined height h, and then the element body 1 is moved to a speed V1 (for example, 10 to 30 mm / s). To lower. As soon as the end face of the base body 1 reaches the surface of the base board 10, the base body 1 is immediately raised at a first speed V2 (for example, 1 to 25 mm / s) and suction of the conductive paste film 22 is started. .
[0037]
Then, the element body 1 is raised at the second speed V3 (for example, 0.05 to 1 mm / s) until the end face of the element body 1 exceeds the reference plane H1 of the conductive paste film 22, and then the element body 1 When the end face is completely separated from the reference plane H1, the end face is raised at a third speed V4 (for example, 10 to 30 mm / s). The first speed V2 is faster than the second speed V3.
[0038]
In the fourth example, as shown in FIG. 5, first, the surface of the conductive paste film 22 is squeezed so as to have a predetermined height h, and then the element body 1 is moved to a speed V1 (for example, 10 to 30 mm / s). To lower. When the end face of the base body 1 reaches the surface of the base board 10, the base body 1 is temporarily stopped (T seconds, for example, within 1 second), and suction of the conductive paste film 22 is started. Thereafter, the element body 1 is raised at a second speed V3 (for example, 0.05 to 1 mm / s), and the third speed V4 (for example, 10 to 10) is reached from the time when the end surface of the element body 1 reaches the reference plane H1. 30 mm / s).
[0039]
In the fourth example, since the bottom dead center holding time T is provided, the effect of suppressing the crescent moon shape is slightly inferior to the first to third examples. However, the conductive paste film 22 is sucked in a state where the end face of the element body 1 is in contact with the surface of the base board 10, and the element body 1 is lifted after the completion of the suction, thereby causing variations in the bottom dead center of the element body 1. The resulting variation in crescent volume is reduced.
[0040]
In the first to fourth examples described above, the timing of starting the suction of the conductive paste film 22 is such that the end face of the element body 1 contacts the conductive paste film 22 after the element body 1 reaches the bottom dead center. Any time may be used as long as it is in progress. Further, in order to apply the conductive paste to the next element body, the timing of extruding the conductive paste film 22 on the base board 10 is the same as that of the conductive element that has been extruded to the end face of the element body 1 to which the conductive paste has already been applied. It is necessary to set so that the paste film 22 does not adhere.
[0041]
(Experimental result)
In the first to fourth examples, external electrodes were formed on a multilayer capacitor having an element body 1 with a length of 0.4 mm, a width of 0.2 mm, and a height of 0.2 mm. The return dimension L of the external electrode 2 is 0.09 mm. The conductive paste film 22 was made of Cu having a viscosity of 20 Pa · s (E type, 1 rpm), and the film thickness h was 50 to 70 μm.
[0042]
In the conventional immersion profile shown in FIG. 9, the average value of the crescent amount D was 31 μm. On the other hand, the average value of the crescent amount D in the first to fourth examples was 17 μm.
[0043]
(Configuration of coating apparatus, see FIGS. 6 and 7)
In the coating apparatus, a rubber sheet 13 is provided on the lower surface side of the base board 10 having a large number of suction holes 11 via a space 12, the space 12 is filled with a conductive paste, and the rubber sheet 13 is moved up and down by an extrusion pin 14. It is configured as follows. The push pin 14 is installed on the base plate 15 and moves up and down integrally as the base plate 15 moves up and down.
[0044]
When the rubber sheet 13 rises as the push pin 14 rises, the conductive paste filled in the space 12 is pushed out to the surface of the base board 10 through the suction holes 11. When the rubber sheet 13 is lowered as the push pin 14 is lowered, the conductive paste on the base board 10 is drawn into the space 12 through the suction hole 11.
[0045]
The state where the end face portion 1a of the element body 1 is immersed in the conductive paste film 22 is as shown in FIG. In this coating apparatus, the suction holes 11 are uniformly distributed on the base board 10 in order to efficiently suck the conductive paste film 22 (see FIG. 7B). The diameter and pitch of the suction holes 11 are preferably set so that the plurality of suction holes 11 face the end face of the element body 1. The suction hole 11 is preferably opposed to the peripheral edge of the end face of the element body 1.
[0046]
(Other embodiments)
In addition, the manufacturing method of the electronic component which concerns on this invention is not limited to the said embodiment, It can change variously within the range of the summary.
[0047]
In particular, the step of reducing the thickness of the conductive paste film 22 can be performed by means of blowing air to the conductive paste film 22. That is, as shown in FIG. 8, after the element body 1 is immersed in the conductive paste film 22, air may be blown from the nozzle 25 to reduce the thickness of the conductive paste film 22 around the end face portion 1a. .
[0048]
【The invention's effect】
As is apparent from the above description, according to the present invention, the force that reduces the reference surface of the conductive paste film that immerses the end face portion of the element body wets the conductive paste attached to the end face portion of the element body. Since it acts in the direction which suppresses a rise, the crescent shape of the formed external electrode becomes small.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an external electrode forming step in a method for manufacturing an electronic component according to the present invention.
FIG. 2 is a graph showing a first example of an immersion profile and suction timing in an external electrode formation step.
FIG. 3 is a graph showing a second example of the immersion profile and suction timing in the external electrode forming step.
FIG. 4 is a graph showing a third example of the immersion profile and suction timing in the external electrode forming step.
FIG. 5 is a graph showing a fourth example of the immersion profile and suction timing in the external electrode forming step.
FIG. 6 is a cross-sectional view showing an outline of a coating apparatus used in the manufacturing method according to the present invention.
7A is a cross-sectional view schematically showing the main part of the coating apparatus, and FIG. 7B is a plan view showing the positional relationship between the suction holes and the element body.
FIG. 8 is an explanatory diagram showing a state in which air is blown onto the paste film in order to reduce the thickness of the conductive paste film.
FIG. 9 is a graph showing a conventional immersion profile.
FIG. 10 is a front view showing an external electrode formed by a conventional immersion profile.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Element body 1a ... End surface part 2 ... External electrode 10 ... Base board 11 ... Suction hole 22 ... Conductive paste film 25 ... Nozzle for air spraying H1 ... Reference plane h ... Thickness of conductive paste film

Claims (10)

Dipping the element body of the electronic component into a conductive paste film that maintains the thickness of the end surface portion of the element body to a predetermined reference surface; and
Raising the element body and pulling up the end face portion from the conductive paste film, and applying a conductive paste to the end face portion;
A step of lowering the reference surface of the conductive paste film after the end face portion of the element body is immersed in the conductive paste film and before the end face portion is pulled up from the surface of the conductive paste film;
Equipped with a,
When the end face of the element body is lowered to bottom dead center, when the end face portion of the element body is immersed in the conductive paste film, and when the element body is temporarily stopped rising, or the element body Lowering the reference surface of the conductive paste film at any time when the element body is once stopped when the end surface of the lowering to the bottom dead center,
A method of manufacturing an electronic component characterized by the above. 2. The method of manufacturing an electronic component according to claim 1, wherein the step of lowering the reference surface of the conductive paste film is performed by suction means provided on the lower surface side of the conductive paste film. 3. The conductive paste film is formed to have a predetermined thickness on a base board having a plurality of suction holes, and the reference plane is lowered by being sucked from the suction holes. The manufacturing method of the electronic component of description.   4. The method of manufacturing an electronic component according to claim 3, wherein the suction holes are uniformly distributed in the base board, and a plurality of suction holes are opposed to an end face of the element body.   The method of manufacturing an electronic component according to claim 4, wherein the suction hole faces a peripheral portion of an end face of the element body.   The method of manufacturing an electronic component according to claim 3, wherein an end surface of the element body is lowered to a surface of the base board.   The method of manufacturing an electronic component according to claim 2, wherein the element body is raised immediately after the end face of the element body is lowered to the bottom dead center.   Immediately after the end face of the element body is lowered to the bottom dead center, the element body is raised at the first speed, and the rise of the element body is temporarily stopped until the end face rises to the reference surface of the conductive paste film. 7. The method of manufacturing an electronic component according to claim 2, wherein the element body is then raised at a second speed.   Immediately after the end face of the element body is lowered to the bottom dead center, the element body is raised at the first speed, and the element body is raised at the second speed until the end face exceeds the reference plane of the conductive paste film. 7. The method of manufacturing an electronic component according to claim 2, wherein the element body is then raised at a third speed. Said first speed method for manufacturing the electronic component according to claim 8 or claim 9, wherein the higher than said second speed.

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