JP3071115B2 - Manufacturing method of chip-shaped 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 producing a chip-type electronic component such as a solid electrolytic capacitor.

[0002]

2. Description of the Related Art Chip-shaped electronic components such as a solid electrolytic capacitor, a chip-shaped resistor, a chip-shaped coil, etc., as shown in FIG.
The electronic component element (4a) is accommodated in the mold (100), and the space (10) formed between the electronic component element (4a) and the mold (100) is formed.
2) Fill the inside with molten resin at a high pressure from a gate (101) (inlet of molten resin) leading to the space (hereinafter referred to as injection molding), cover the electronic component element (4a) with resin, and Forming a shell.

The injection pressure of the molten resin in the above injection molding is large, and the mechanical shock at this time may impair the function of the electronic component. This will be described for the case where the electronic component is a solid electrolytic capacitor. As is well known, a solid electrolytic capacitor is formed by forming a dielectric oxide film on the surface of a valve metal such as Ta, Al, or Nb, and forming a solid electrolyte such as a conductive polymer on the dielectric oxide film. Is formed, and the capacitor element is coated with a resin by injection molding to form an outer shell.

In the production of the solid electrolytic capacitor,
When the capacitor element is coated with the resin for forming the outer shell, a mechanical shock due to the injection pressure of the resin damages the dielectric oxide film on the valve metal surface, which causes an increase in leakage current, which is considered to be the cause. In order to suppress an increase in leakage current, the injection pressure of the molten resin is reduced, or a resin is partially applied to the capacitor element (4) before the outer shell is formed to reinforce the resin. As shown in (1), a resin coating layer (8) is formed on the entire surface of the capacitor element (4) to reduce the mechanical shock caused by the injection pressure of the molten resin for forming the outer shell.

[0005]

However, if the injection pressure of the molten resin is reduced, poor wraparound of the molten resin in the mold occurs, resulting in poor molding and reliability. The following problems also occur when the capacitor element (4) is partially reinforced by applying a resin, or when a resin coating layer (8) is formed on the entire surface of the capacitor element to reduce mechanical shock. For the partial reinforcement of the capacitor element (4), mainly the surface close to the gate, generally the anode lead
Although the resin is applied to the drawing surface (41) of (11), this operation cannot be automated due to the small size of the capacitor element (4) and must be performed manually by a skilled person, which is extremely inefficient.

Further, as shown in FIGS. 6 and 7, a resin liquid such as an epoxy resin liquid or a silicon resin liquid is applied to the entire surface of the capacitor element (4) and solidified to form an elastic resin coating layer (8). However, in order to effectively protect the capacitor element (4) from mechanical shock, the thickness of the coating layer (8) increases, which covers the entire surface of the capacitor element (4). There is a problem that the chip-shaped electronic component including the thickness of 9) becomes large, and the coating resin adheres to the electrodes to lower the reliability. Further, time is required for solidifying the resin liquid, and workability is poor. The present invention clarifies a method of manufacturing a chip-shaped electronic component that can solve the above-described problem.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing a chip-shaped electronic component in which an electronic component is coated with a resin by injection molding to form an outer shell (9).
Before forming the electronic component element, a buffer material (5) made of synthetic resin, rubber, paper, cloth, or the like is applied only to the surface of the electronic component element facing the mold gate, and the injection pressure of the molten resin is reduced. Cushioning material
Relieve by (5).

[0008]

According to the present invention, the mechanical shock to the electronic component element due to the inflow resin at the time of injection molding is cushioned (5).
Therefore, it is not necessary to reduce the injection pressure of the molten resin as in the related art. Therefore, occurrence of molding defects, such as when the injection pressure is reduced, can be suppressed.

Further, unlike the case where the elastic coating resin layer is coated on the entire surface of the electronic component element, the miniaturization of the chip component is not hindered. Further, it is not necessary to consider the time required for solidifying the coating resin liquid. Furthermore, the coating resin liquid does not adhere to the electrodes to reduce the reliability. The work of mounting the cushioning material (5) on the electronic component element can be easily automated by forming an adhesive layer on the cushioning material (5). From the above points, a high-performance and highly reliable chip-shaped electronic component can be efficiently manufactured.

When the present invention is applied to the manufacture of a high performance capacitor using a conductive polymer such as pyrrole, aniline, thiophene or the like as a solid electrolyte, mechanical shock during injection molding is applied in advance to the element surface facing the gate of the mold. Can be mitigated by the cushioning material (5) provided in the capacitor element, thereby suppressing an increase in leakage current due to damage to the dielectric oxide film on the valve metal surface of the capacitor element.

[0011]

The following is a description of a solid electrolytic capacitor. In the solid electrolytic capacitor, a dielectric oxide film is formed on the surface of a valve metal such as Ta, Al, Nb, etc. by a method such as anodic oxidation. A capacitor element (4) having a conductive polymer, such as pyrrole, thiophene, or aniline, formed as an electrolyte on the film is subjected to an outer shell by injection molding.
(9) is formed. In the following examples, a Ta sintered body element was adopted as the valve metal. In the molding of this kind of resin, transfer molding is performed in the case of a thermosetting resin, and injection molding is performed in the case of a thermoplastic resin, and injection molding is generally injection molding. However, transfer molding is also considered to be a type of injection molding, and is understood as such in the present invention.

Example 1 As shown in FIGS. 1 and 2, a lead wire lead-out surface (41) of an element member (1) composed of a Ta sintered body and a lead wire (11) drawn out from the inside thereof. Then, the sheet-like cushioning material (5) is applied by passing the lead wire (11) through. The sheet-like cushioning material (5) is formed of a fluorine resin, and has a thickness of 0.5 mm.
It is 2 mm, and a hole (51) for inserting the lead wire (11) is formed in the center. Next, the element member (1) was formed by anodic oxidation in an aqueous solution of H ₃ PO ₄ to form a dielectric oxide film.

[0013] The element member (1) is connected to an aqueous hydrogen peroxide solution (1 m
(l / l) for 10 minutes and the pyrrole monomer for 30 minutes to form a chemically polymerized polypyrrole film on the oxide film,
An electropolymerized polypyrrole film (2) was formed thereon in an acetonitrile solution containing a pyrrole monomer (0.1 mol / l) and paratoluenesulfonic acid (0.05 mol / l), and a carbon and silver paste (3 ) To pull out the cathode to obtain a capacitor element (4). Lead wire (11) for the capacitor element (4)
And metal terminal plates (6) (61) on the lower surface of the capacitor element (4).
Were connected by welding or bonding. Next, the capacitor element
(4) The cushioning material (5) was set in the mold with facing the gate of the mold, and an epoxy resin was injection-molded at 175 ° C. and an injection pressure of 35 kg / cm ² to form an outer shell (9). .
The metal terminal plates (6) and (61) projecting from the outer shell (9) were bent along the outer shell. Next, a voltage was applied at 125 ° C. for 2 hours to perform an aging process to obtain a solid electrolytic capacitor.

"Embodiment 2" is different from Embodiment 1 in the order of mounting the sheet-like cushioning material (5). As in Example 1,
The element member (1) constituted by the Ta sintered body and the lead wire (11) drawn out from the inside was anodized in an aqueous solution of H ₃ PO ₄ to form a dielectric oxide film. Next, the element member (1) was placed in an aqueous solution of hydrogen peroxide (1 mol / l) for 10 minutes.
Exposure to a pyrrole monomer for 30 minutes to form a chemically polymerized polypyrrole film on the oxide film,
(0.1 mol / l) and paratoluenesulfonic acid (0.05 mol / l)
/ L) to form an electrolytically polymerized polypyrrole film (2) in an acetonitrile solution, and the cathode was drawn out with carbon and silver paste (3) to obtain a capacitor element (4). After the capacitor element (4) was formed in the above process, the lead wire (11) was passed through the buffer material (5), and the buffer material (5) was applied to the lead wire lead-out surface (41).

Next, the lead wire (11) of the capacitor element (4)
And metal terminal plates (6) (61) on the lower surface of the capacitor element (4).
Were connected by welding or bonding. In the following steps, the capacitor element (4) is set in the mold with the cushioning material (5) facing the gate of the mold in the same manner as in Example 1.
An epoxy resin was injection molded at a temperature of 35 ° C. and an injection pressure of 35 kg / cm ² to form an outer shell (9). The metal terminal plates (6) and (61) projecting from the outer shell (9) were bent along the outer shell. Then, 1
A voltage was applied at 25 ° C. for 2 hours to perform an aging process to obtain a solid electrolytic capacitor.

[Embodiment 3] Instead of the sheet-like cushioning member 5 made of fluororesin of the above-mentioned embodiment 2, a rubber cushioning member of the same shape is used.
(5) Using the same procedure as in Example 2.

"Example 4" A sheet-like cushioning material 5 of the same shape was used in place of the sheet-like cushioning material 5 made of fluororesin of Example 2, and the procedure was the same as in Example 2. did.

"Example 5" Example 2 The same procedure as in Example 2 was carried out, except that the cushioning material 5 of the same shape was used instead of the sheet-like cushioning material 5 made of fluororesin.

Example 6 As shown in FIGS. 4 and 5, instead of the sheet-like cushioning material (5) made of fluoric resin having a uniform thickness in Example 2, a thicker central portion is formed to form an outer shell. The same procedure as in Example 2 was carried out using a synthetic resin buffer material (5) whose surface on the inlet side of the molten resin was gradually inclined in a conical shape.
In this case, the molten resin at the time of forming the outer shell (9) by injection molding is guided by the slope of the cushioning material (5), so that the circumference of the resin is improved.

[Comparative Example 1] In the above-mentioned Example 1, the buffer material (5) was omitted, and injection molding was performed at 175 ° C and an injection pressure of 35 kg.
/ Cm ² (FIG. 8).

"Comparative Example 2"
Omitting (5), the injection molding was performed at 175 ° C and the injection pressure was 15 kg /
Performed in cm ² .

[Comparative Example 3] In the process of Example 1, the buffer element (5) was omitted to form a capacitor element (4), and then a silicone resin liquid was applied to the entire element, and the resultant was heated at 150 ° C for 3 hours. After solidification, the surface of the capacitor element (4) was covered with an elastic silicone resin layer (8). Injection molding at 175 ° C, injection pressure 3
This was performed at 5 kg / cm ² , and subjected to aging treatment to obtain a capacitor (FIGS. 6 and 7). Table 1 shows the inspection results of the leakage current and the molding failure according to the embodiment and the comparative example.

[0023]

[Table 1]

According to the present invention, in the production of a high-performance capacitor using a conductive polymer such as pyrrole, aniline, thiophene or the like as a solid electrolyte, a mechanical shock at the time of injection molding is previously set on the element surface facing the gate of the mold. The buffer material (5) can alleviate the damage, thereby preventing the dielectric oxide film on the valve metal surface of the capacitor element from being damaged and increasing the leakage current. Also, high reliability can be obtained without reduction of injection pressure in injection molding and molding failure due to resin coating or the like.

Further, the mounting of the cushioning material (5) to the capacitor element can be easily automated, for example, by forming an adhesive layer on the back surface of the cushioning material (5). Further, unlike the conventional case where the coating layer (8) of the elastic resin is formed on the entire surface of the capacitor element, there is no need to consider the solidification time of the coating resin liquid, so that the number of steps can be reduced and the production efficiency is improved I do. In the first to fifth embodiments, the thickness of the sheet is 0.2 m.
If you have been a m ^t thicker as possible as a matter of course there is an effect. The present invention is not limited to the configuration of the above embodiment, and various modifications are possible within the scope of the claims.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a cushioning material and a metal terminal plate are attached to an electronic component element.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a cross-sectional view of the electronic component.

FIG. 4 is a perspective view when a cushioning material of another embodiment is used.

FIG. 5 is a sectional view of an electronic component using a cushioning material of another embodiment.

FIG. 6 is a perspective view of a comparative example in which the surface of an electronic component element is coated with a resin.

7 is a cross-sectional view of the electronic component after the process of FIG.

FIG. 8 is a sectional view of another comparative type.

[Explanation of symbols]

 (1) Element member (2) Polypyrrole film (3) Carbon and silver paste layer (4) Capacitor element (5) Buffer material (6) Metal terminal plate (8) Coated resin layer (9) Outer shell

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI H01G 9/08 H01G 1/02 R (58) Fields investigated (Int.Cl. ⁷ , DB name) H01G 4/00-4 / 40 H01G 13/00-13/06

Claims (5)

(57) [Claims] 1. A method of manufacturing a chip-shaped electronic component in which a resin outer shell (9) is formed on an electronic component element by injection molding, wherein a cushioning material (5) made of a synthetic resin, rubber, paper, or cloth. ) Is prepared in advance, and before the outer shell (9) is formed by injection molding, the cushioning material (5) is provided only on the surface of the electronic component element facing the gate (101) of the mold (100). ), And the injection pressure of the molten resin for injection molding is reduced by the buffer material (5). 2. The electronic component element is a capacitor element (4) in which a dielectric oxide film is formed on a surface of a valve action metal, and a conductive polymer as an electrolyte is formed on the film. The method for producing a chip-shaped electronic component according to claim 1. 3. The cushioning material (5) has a sheet-like shape in which a through hole is provided in a central portion of a surface facing the gate (101), and a lead wire for leading out an electrode of the electronic component element. 2. The method for producing a chip-shaped electronic component according to claim 1, wherein (11) is penetrated through a through hole of said cushioning material (5). 4. The buffer material (5) has a shape in which a through hole is provided in a central portion of a surface facing the gate (101) and the central portion is raised to form a slope. 2. The method for producing a chip-shaped electronic component according to claim 1, wherein a lead wire (11) for leading out an electrode of the component element is penetrated through a through hole of the buffer material (5). 5. The chip according to claim 1, wherein an adhesive layer made of an adhesive or tacky material is formed on a surface of said cushioning material facing said electronic component element. Of electronic components.