JPS60213017A - Chip-shaped solid electrolytic condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a chip-shaped solid electrolytic capacitor in which conductive metal terminals are connected to electrodes of a capacitor element.

Structure of conventional example and its problems In recent years, the mounting of chip-shaped solid electrolytic capacitors onto the board has been automated, so the solder bath K, which contains molten solder, and the chip fixed in place on the board with adhesive. The heat resistance of chip-shaped solid electrolytic capacitors has become important as methods such as so-called solder dips, in which soldering is performed through chip-shaped electronic components, have come into use.

A conventional example of a chip-shaped tantalum solid electrolytic capacitor, which is an example of a chip-shaped solid electrolytic capacitor, will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional view of a capacitor element. In the figure, reference numeral 1 denotes a protruding lead-out wire of tantalum metal, which is partially inserted into a tantalum sintered body 2 made by compression molding and sintering powdered tantalum into a cylinder or rectangular parallelepiped. A tantalum oxide film 3 is formed on the surface of the tantalum sintered body 2 to serve as an anode body, a manganese dioxide layer 4 is formed on this IIJff body, and a carbon layer 6 as a cathode is formed on the surface of the manganese dioxide layer 4. A cathode current collecting layer 6 is formed by coating the surface of the carbon layer 5 with a thermoplastic silver paint (acrylic, cellulose, vinyl chloride) that can be soldered. A capacitor element is constructed by the following.

FIG. 2 shows a conductive metal terminal connected to an electrode portion of a capacitor element. In the figure, 7 is a conductive anode side metal terminal connected to the anode electrode of the capacitor element, that is, the tantalum metal protruding lead wire 1 shown in Figure @1, and is soldered to the cathode current collecting layer of the 8-digit capacitor element. This is a conductive metal terminal on the cathode side that is connected by attaching it. The anode side metal terminal 7 is
Since it is connected to the tantalum metal protruding lead wire 1 shown in FIG. 1 by spot welding, the anode side metal terminal 7KV
i A contrivance has been made to reduce the metal width by providing a punched hole 7a as shown in FIG. 2 to make the metal easier to melt.

Next, two typical examples of the connection method between the cathode current collecting layer and the cathode side metal terminal of the capacitor element will be shown.

(Re) Connect the cathode current collecting layer 6 of the capacitor element shown in Fig. 1 and the cathode side metal terminal 8 whose surface has been treated with solder plating etc. using a cow FB (Sn/Pb=6/4 or Sn). In the above method, a chip-shaped tantalum solid electrolytic capacitor is soldered onto a substrate (240°C to 240°C).
If soldering is performed using the method (250C', time required for 2 to 3 seconds), the melting point of the solder connecting the cathode current collecting layer 6 of the capacitor element and the cathode side metal terminal 7 will be the temperature of the solder dip. Since the temperature is lower, the solder may melt and the solder connection may come off, resulting in low reliability.

(2) There is a method of fixing and drying the cathode current collecting layer 6 of the capacitor element shown in Figure 1 and the cathode side metal terminal 8 using a conductive adhesive (epoxy, phenol, polyimide) and then connecting them. . In the above method, it takes time for the conductive adhesive to harden, which makes it unsuitable for mass production.In addition, compared to the method described in item 1 above, the soldering method is difficult to connect the cathode current collecting layer 6 of the capacitor element to the cathode. It has the disadvantage that the adhesion strength with the side metal terminal 8 is only 1.5%.

As mentioned above, each connection method has problems in terms of Vi mass productivity and reliability, and there is a desire to develop a chip-shaped solid electrolytic capacitor that satisfies mass productivity and reliability at the same time.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned drawbacks and provides a chip-shaped solid electrolytic capacitor that can be easily mass-produced and is highly reliable.

Structure of the Invention In order to achieve this object, the chip-shaped solid electrolytic capacitor of the present invention has a conductive metal terminal connected to the electrode of a capacitor element by a conductive metal having a solidus line of 240 to 300C. According to this configuration, the solidus line of the metal that connects the electrode of the capacitor element and the conductive metal terminal is higher than the melting temperature of the solder used when mounting the chip-shaped solid electrolytic capacitor to the printed circuit board with equal pressure. The connection between the electrode of the capacitor element and the conductive metal terminal will not come off due to the heat of the solder when it is mounted on a board or the like.

DESCRIPTION OF EMBODIMENTS An example of the present invention will be described below with reference to the drawings regarding a chip-shaped tantalum solid electrolytic capacitor, which is one of chip-shaped solid electrolytic capacitors.

A chip-shaped tantalum solid electrolytic capacitor KVi, which is a practical example of the present invention, uses a capacitor element shown in FIG. However, as the silver conductive paint for the cathode current collecting layer, a mixture of solderable acrylic thermoplastic resin and silver powder is used. In addition, for the metal terminal on the cathode side, a 1-2 μm copper plating is applied to a 100 μm nickel plate material, and
A metal plate plated with B (Pb/5n=1/9) and punched out with a die is used.

The pan electrical paint layer, which is the cathode current collecting layer of the capacitor element, and the metal terminal on the cathode side are bonded with high melting point solder (Sn/Pb
/Ag=88/10. /2, liquidus line 240 (:'.

Solidus line 2 yotl') and agin system six (specific gravity o
, s5), instantaneous soldering is performed at a temperature of 3ootZ' and a time of 1 second. The protruding wire on the anode side of the capacitor element and the metal terminal on the anode side are spot welded.
Make the connection. FIG. 3a shows a front view in which the metal terminal 1o on the anode side is connected to the capacitor element 9 by spot welding, and the metal terminal 11 on the cathode side is connected to the solder 12 with a high melting point by rosin-based 7 lux. Both metal terminals 10.1
The capacitor element 9 to which 1 is connected has metal terminals 10 and 11 pulled out from both ends as shown in FIG. Indicate the capacitance and connect both metal terminals 10.1 as shown in Figure 3C.
#1 is bent at right angles along both side surfaces of the molded resin 13 to form terminals. After that, a chip-shaped tantalum solid electrolytic capacitor is produced by aging and fC.

When mounting a chip-shaped solid electrolytic capacitor on a printed circuit board, there are two methods: hot plate reflow and solder dip. The above two methods were tested by changing the type of solder used to connect the metal terminal on the cathode side of the chip-shaped tantalum solid electrolytic capacitor of the present invention and the cathode current collecting layer of the capacitor element.

(Experiment example 1) Figure 4 shows an experimental setup using hot plate reflow.

The chip-shaped tantalum solid electrolytic capacitor 14 is placed on the top surface of a printed circuit board 16 (thickness: 10 m, material: phenol), and the hot plate 16 is heated by the heater 17 to melt the solder applied to the surface of the printed circuit board 14. , the metal terminals of the chip-shaped tantalum solid electrolytic capacitor 14 are connected to the surface of the printed circuit board 16. Using the hot plate reflow method described above, we experimented with solder popping out of the chip-shaped tantalum solid electrolytic capacitor by changing the type of solder that connects the cathode layer of the chip-shaped tantalum solid electrolytic capacitor to the cathode side metal terminal. The results shown in Table 1 below were obtained.

The temperature of the hot plate is 26oC - Table 1 A (conventional product) -S n/P b = e/4, solidus line 183CB (conventional product) - 8n/Aq = 98/2.
Solid phase 1j1221pC (product of the present invention)--3n/Pb/
Ag=10/88/22° solidus line 240 or 276
C “○” mark ・・・・・・No solder protrusion “x” mark
...Solder popping out (Experiment Example 2) Chip-shaped tantalum solid electrolytic capacitors using solders A, B, and C similar to those in Experiment Example 1 were dipped in solder for different times to form a chip-shaped tantalum solid electrolytic capacitor. The number of open circuits in 10,000 electrolytic capacitors was investigated and the results shown in Table 2 below were obtained. The temperature of the solder dip was kept constant at 260C.

Table 2 As is clear from the results shown in Experimental Examples 1 and 2 above, according to the present invention, the solder connecting the capacitor element and the cathode side metal terminal does not jump out, and the open occurrence rate is also reduced. Although not shown in Experimental Examples 1 and 2, solid phase 1j3
Since it is known that the use of 00C solder does not have an adverse effect on solid electrolytic capacitors, it is also possible to use solder with a solidus line of 300C. Therefore, a chip-shaped tank solid electrolytic capacitor using solder C according to an embodiment of the present invention can ensure sufficient reliability even when mounted on a printed circuit board by dipping and hot plate reflow. However, simply using a solder with a high melting point causes an increase in leakage current due to deterioration of the tantalum oxide film, and a decrease in tan δ characteristics due to deterioration of the conductive thermoplastic resin. Therefore, in the chip-shaped tantalum solid electrolytic capacitor of the embodiment of the present invention, a conductive thermoplastic resin with little thermal deterioration is used, and the soldering temperature is 320°C.
In other words, as long as the common mode line of the solder is 3 ooc or less (soldering is carried out at a temperature 2 oC higher than the solidus line of the solder), thermal deterioration in solid electrolytic capacitors is minimal. can be suppressed to

Effects of the Invention As described above, the present invention connects the electrode of a capacitor element and a conductive metal plate using a metal with a high melting point of 240 to 5oOC. Even during mounting, the connection between the electrode of the capacitor element and the conductive metal plate can be prevented from opening, and a sufficiently reliable chip-shaped solid electrolytic capacitor can be provided.

Moreover, we also took into consideration that simply connecting with a metal with a high melting point could lead to thermal deterioration of the characteristics of the connection part, so we decided to connect the electrodes of a chip-shaped solid electrolytic capacitor called solid phase m240~3ooC with a conductive metal plate. A metal with an optimal temperature is used for the connection, which has great effects.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a chip-shaped tantalum solid electrolytic capacitor, Figure 2 is a perspective view of the anode side metal terminal and the cathode side metal terminal, and Figure 3a is the connection between the anode and cathode side metal terminals. Protruding lead wire (electrode), θ... cathode layer (electrode L9...
・・・・Capacitor element ÷ Yorichusou #≠#Bu, 10...
...Anode side metal terminal (conductive metal terminal), 11...
...Cathode side metal terminal (conductive metal ring, 12...
...Solder (hard, #A class 240-300C conductive metal). Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] (1) A chip-shaped solid electrolytic capacitor in which a conductive metal terminal is connected to the electrode of a capacitor element by a conductive metal with a solidus line of 240 to 300C. 1) A chip-shaped chip according to claim 1, using a metal containing lead or a lead-tin alloy as a main component and containing 2 to 20 weight percent silver as the conductive metal with a solidus line of 240 to 300 C. Solid electrolytic capacitor. (3) Using a conductive metal with a solidus line of 240~300C,
The chip-shaped solid electrolytic capacitor according to claim 1, which uses an alloy having a tin content of 20% by weight or less.