JPS6131609B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a chip-shaped solid electrolytic capacitor. Conventionally, chip-shaped solid electrolytic capacitors that are face-bonded and attached to printed circuit boards, etc. have been covered with resin by transfer molding, but these have been large in size and expensive. In addition, there was a bare type that was not transfer molded and had a solderable metal terminal welded to the lead drawn out from the anode body of the capacitor element, but the dimensional accuracy was poor, the mechanical strength was low, and the printed circuit board It was difficult to automate the installation. In addition, all of the above-mentioned products require a step of welding a metal terminal to the lead-out lead, resulting in a complicated structure and difficulty in downsizing. The present invention eliminates the above-mentioned drawbacks and provides a method for manufacturing a chip-shaped solid electrolytic capacitor that is small, easy to manufacture, and can be manufactured at low cost. The present invention will be explained below with reference to embodiments shown in FIGS. 1 to 4. First, as shown in FIG. 1, the lead-out leads 1 of a plurality of prismatic, cylindrical, etc. anode bodies 2 made of valve metal such as tantalum or aluminum and having lead-out leads 1 are welded and connected to the power supply bar 3. Then, a dielectric oxide film 4 is formed on the surface of the anode body 2, and a semiconductor solid electrolyte layer 5 such as manganese dioxide and a cathode conductive layer 6 such as carbon and silver paste are sequentially formed on the film. Next, a reinforcing resin 7 such as epoxy is applied to the lead-out portion of the lead-out lead 1 and cured, and a resin layer 8 is formed using the epoxy powder resin to cover the anode body 2 by electrostatic coating. And lead 1 made of tantalum, aluminum, etc.
And the resin layer 8 attached to the bottom of the anode body 2 is
As shown in the figure, after being selectively removed by air blasting or the like, the remaining resin layer 8 is cured. Further, alumina powder is sprayed onto the resin layer 8 and foreign matter adhering to the lead-out lead 1 to remove the deposit by a so-called sandblasting method, and the dielectric oxide film 4 on the surface of the lead-out lead 1 is removed.
is removed, and unevenness 1a is formed on the metal surface.
Next, the cathode side after removing the resin layer 8 at the bottom of the anode body 2
Applying a conductive layer 9 such as silver paste to the electrode part,
After hardening, a conductive layer 10 containing dissimilar metals such as iron and copper in silver paste is further applied and hardened. At this time, the conductive layer 10 is also applied to the anode side and hardened. Next, in order to separate the lead-out lead 1 from the power supply bar 3, a notch is made in the lead-out lead 1. Then, an electroless plating process made of a solderable metal such as nickel or copper is performed to form an electroless plating layer 11 on the conductive layer 10 and the lead-out lead whose surface has the unevenness 1a. Thereafter, a solder layer 12 is formed by contacting with molten solder, and after aging treatment, the lead-out lead 1 is bent from the notch and separated from the power supply bar to complete the process. The method for manufacturing a chip-shaped solid electrolytic capacitor of the present invention is carried out as described above. Therefore, since the external electrode does not require a welding process and a metal plating layer is formed, the external dimensions are significantly smaller, and the oxide film on the surface of the lead-out lead is removed to form unevenness, so it is electroless. The adhesion with the plating layer 11 becomes strong, and the plating layer does not peel off due to bending of the lead-out lead during handling, so that a highly reliable capacitor can be obtained. The table shows the plating peeling test results for a chip solid tantalum electrolytic capacitor with a rating of 3.15V and 100μF.

[Table] Test conditions Fix the tip of the lead out, bend the capacitor body 30 degrees in any direction, and then return it to its original position. Then bend it diagonally in the opposite direction by 30 degrees and then return it to its original position. This cycle is performed once. Fig. 5 shows the results of a load life test with a reduced voltage applied at 125°C using a chip-shaped solid tantalum electrolytic capacitor with the same rating as above, mounted on a printed circuit board. The conventional product described above does not include the step of forming irregularities on the surface of the lead-out lead in the embodiment of the present invention. As is clear from the table and FIG. 5, the product of the present invention has less variation in leakage current characteristics and loss than the conventional product, proving that it is extremely stable. As mentioned above, the chip-shaped solid electrolytic capacitor manufactured by the manufacturing method of the present invention is small, has electrodes connected extremely firmly, is extremely advantageous in terms of reliability, and has great industrial and practical value. It is something.

[Brief explanation of the drawing]

Figures 1 to 4 are explanatory diagrams of the manufacturing process of a chip-shaped solid electrolytic capacitor according to an embodiment of the present invention, and Figure 5 shows a sample obtained by the manufacturing method of the present invention (product of the present invention) and a conventional product. A is a loss-time characteristic diagram, and B is a leakage current-time characteristic diagram. 1: lead-out lead, 1a: unevenness, 2: anode body,
4: dielectric oxide film, 5: solid electrolyte layer, 6: cathode conductive layer, 8: resin layer, 9, 10: conductive layer, 1
1: Electroless plating layer, 12: Solder layer. 〓〓〓〓

Claims (1)

[Claims] 1 A dielectric oxide film 4 is formed on the surface of an anode body 2 made of a valve metal having a lead-out lead 1, a solid electrolyte layer 5 and a cathode conductive layer 6 are formed on the film, and the anode is coated by an electrostatic coating method or the like. After forming the resin layer 8 so as to cover the body, the resin layer 8 attached to the lead-out lead 1 is removed by sandblasting or the like, and the unevenness 1a is formed on the surface of the lead-out lead 1. A chip characterized in that conductive layers 9 and 10 are formed on the surface, and an electroless plating layer 11 and a solder layer 12 are sequentially formed on the unevenness 1a and the conductive layers 9 and 10 to constitute an anode electrode section and a cathode electrode section. A method for manufacturing solid electrolytic capacitors.