JPH0240212B2 - CHITSUPUGATAKOTAIDENKAIKONDENSANOSEIZOHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a chip-type solid electrolytic capacitor, and particularly to improvements in moisture-proof preparation and lead frame connection means.

[Technical background of the invention and its problems] Generally, a chip type solid electrolytic capacitor has an anode wire 2 attached to a valve metal powder, as shown in Fig. 6, for example.
A lead frame 23 is connected to each of the anode wire 21 and the cathode conductive layer constituting the outer surface of the capacitor element 22 of the capacitor element 22, which is formed by embedding and sintering the capacitor elements 1 and 2 in a known process. The exterior 24 is applied by transfer molding, and the capacitor body 25 and the lead frame 23 are then attached to the capacitor body 2.
5 along both side surfaces 26 and bottom surface 27. However, since the exterior thickness of the chip-type solid electrolytic capacitor constructed in this way is generally extremely thin at 0.3 to 0.5 mm, attempts have been made to apply an undercoat to improve moisture resistance. Since the object is small, the lead frame 23 is plate-shaped, and the lead frame 23 is led out in the opposite direction, it has been difficult to apply the undercoat with high precision. That is, the capacitor element 21
It is impossible to form an undercoat film by immersing only the part in the undercoat paint liquid.
When applying an undercoat, it must be applied with a brush, which not only poses problems in workability, but also because the undercoat material is in the form of a paint, causing it to flow as shown in FIG. 7 and causing damage to the lead frame 28. The undercoat film 29 may adhere to the necessary areas, the thickness of the adhesion may become uneven, and the undercoat material may be exposed from the surface of the exterior 30, or the undercoat material that has adhered unnecessarily may become attached to the mold during transfer molding. There were many problems that needed to be resolved, such as adhesion to the surface. For this reason, methods have been adopted to improve the moisture resistance of the capacitor element itself by improving the method of forming MnO ₂ , but it is still not perfect and in the end, the capacitor was packaged without an undercoat in preparation for a certain amount of moisture absorption. This is the current situation. In the figure, 31 is a capacitor element.

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and employs a means for performing an undercoat treatment before connecting the lead frame and removing the undercoat film at the connection portion of the lead frame. Then,
It is an object of the present invention to provide a method for manufacturing a chip-type solid electrolytic capacitor that can prevent characteristic deterioration due to moisture absorption and has good workability.

[Summary of the Invention] The method for manufacturing a chip-type solid electrolytic capacitor of the present invention involves immersing a capacitor element made by integrally embedding an anode wire in valve metal powder and sintering it in a synthetic resin paint, and coating the entire circumference of the capacitor element. Before curing the undercoat film formed on the surface, remove the paint film on the part that will be bonded to the lead frame, then heat and harden the paint film on other parts, and connect the lead frame to the part where the paint film was removed. It is characterized by applying the exterior with transfer molding.

[Embodiments of the Invention] The details of the present invention will be described below with reference to the drawings. That is, as shown in Fig. 2, a valve metal powder anode wire 1 such as tantalum or aluminum is
The capacitor element 2 is made by sequentially forming a dielectric oxide film, a solid electrolyte, a carbon graphite layer, and a cathode layer consisting of a silver metal layer on the surface of an anode body which is integrally embedded and sintered with, for example, epoxy, urethane, acrylic, etc. A means for forming an undercoat film 4 on the entire circumferential surface of the capacitor element 2 as shown in FIG. a means for removing a part of the coat film 4 by, for example, air blasting or sandblasting treatment to form a film removed portion 5; a means for subsequently hardening the undercoat film 4 by heat treatment;
As shown in the figure, a lead frame 6 which becomes an anode plate-shaped metal terminal is connected to the anode wire 1, and a lead frame 7 which becomes a cathode plate-shaped metal terminal is connected to the coating film removal part 5, and an exterior 8 is formed by transfer molding. The capacitor body 9 is formed by bending lead frames 6 and 7 led out from the capacitor body 9 along the side surface 10 and bottom surface 11 of the capacitor body 9. Note that the same parts in FIGS. 1 to 4 are designated by the same reference numerals.

According to the chip-type solid electrolytic capacitor constructed as described above, the undercoat treatment is performed by immersing the lead frames 6, 7 in the synthetic resin paint liquid 3 before connecting the lead frames 6, 7, so that the synthetic resin paint is not applied to the lead frames 6, 7. It is possible to form an undercoat film 4 of uniform thickness only on the 2 parts of the capacitor element without adhesion, and because it is immersed, it is possible to reduce the viscosity of the synthetic resin paint liquid 3, making it possible to form a thinner paint film. It is possible to efficiently prevent characteristic deterioration due to moisture absorption and solve the problems of the conventional method of manufacturing chip-type solid electrolytic capacitors at once.

In the above embodiment, the case where one capacitor element is immersed in the synthetic resin paint liquid was explained as an example, but as shown in FIG. For example, it goes without saying that a plurality of pieces may be supported using the connecting body 15 and immersed in the synthetic resin coating liquid 16 for undercoating treatment.

Next, the chip-type solid tantalum capacitor obtained according to Example (A) of the present invention and the chip-type solid tantalum capacitor obtained according to the conventional reference example (B) without undercoating were tested at 121°C and 22 atmospheres. As a result of investigating the rate of change in capacitance and changes in tanδ characteristics over time in the pressure-shear test under different conditions,
The result is as shown in FIGS. 8 and 9. Example
In (A), it was immersed in a silicone resin paint solution as an undercoat treatment, and the samples were 6V-15μF.Both (A) and (B) had 30 pieces, and the values are average values. As is clear from FIGS. 8 and 9, the capacitance change rate and tan δ of the reference example (B) change over time.
In contrast, the rate of change in Example (A) was small, demonstrating an excellent effect.

[Effects of the Invention] According to the present invention, a capacitor element formed by integrally embedding and sintering an anode wire is immersed in a synthetic resin paint, an undercoat film is formed on the entire circumference of the capacitor element, and the paint film is A process that prevents characteristic deterioration due to moisture absorption by removing the paint film on the part that will be the adhesive surface with the lead frame before curing, and then hardening and connecting the lead frame to the part where the paint film was removed. A method for manufacturing a chip-type solid electrolytic capacitor with good performance can be provided.

[Brief explanation of drawings]

FIGS. 1 to 4 show a first embodiment of the present invention.
The figure is a sectional view showing a completed chip-type solid electrolytic capacitor, FIG. 2 is a schematic diagram illustrating the undercoat means, FIG. A cross-sectional view showing a capacitor element after forming a coating film removal portion of the undercoat coating, FIG. 5 is a schematic diagram illustrating an undercoat means according to another embodiment, and FIGS. 6 and 7 are conventional references. Cross-sectional views showing completed chip-type solid electrolytic capacitors according to examples, No. 8
The figure is a time-capacity change rate characteristic curve diagram, and FIG. 9 is a time-loss characteristic curve diagram. 1, 14... Anode wire, 2, 13... Capacitor element, 3, 16... Synthetic resin coating liquid, 4... Undercoat coating film, 5... Paint film removal section, 6, 7...
Lead frame, 8...exterior, 9...capacitor body, 10...side, 11...bottom.

Claims (1)

[Claims] 1. A means for forming a capacitor element by integrally embedding an anode wire in a valve metal powder and sintering it; a means for immersing and pulling up the capacitor element in a synthetic resin coating solution to form an undercoat film; means for removing a portion of the paint film by air blasting or sandblasting to form a paint film removal section; means for subsequently heating to harden the undercoat film; and a lead for each of the anode wire and the paint film removal section. The method is characterized by sequentially performing a means for connecting the frame, a means for forming a capacitor body by sheathing with a transfer mold, and a means for bending each lead frame derived from the capacitor body along the side and bottom surfaces of the capacitor body. A method for manufacturing a chip-type solid electrolytic capacitor.