JPH09260223A - Anode lead welding device of sintering type capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use the title device capable of being used in common to capacitor elements of various sizes and reduce the influence of heat during welding. SOLUTION: A lead frame 13 is mounted on a frame guide 40 and a tantalum line 3 of a capacitor element 8 is subjected to laser welding to an anode connection side end part of the lead frame 13. In the frame guide 40, movement can be adjusted freely up and down and the movement of the lead frame 13 in vertical and horizontal directions is regulated, and sucked and held by a patch 57. An area near a laser welding part of the frame guide 40 is formed of a material of high heat conduction rate. The lead frame 13 has a bent part 13b which is bent toward above an anode side connection end part and the tantalum line 3 is welded to an upper end of the bent part 13b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anode lead welding apparatus for sintered capacitors.

[0002]

2. Description of the Related Art As a sintered type capacitor, a tantalum solid electrolytic capacitor using a sintered body of tantalum as an anode metal is generally widely used. This tantalum solid electrolytic capacitor 1 is provided with a porous tantalum sintered body 2 made of a valve metal having an anode lead tantalum wire (hereinafter referred to as tantalum wire) 3 as shown in FIG. The dielectric layer 4 is formed, and the cathode layer 7 is further formed on the dielectric layer 4 with the manganese dioxide layer 5 and the carbon layer 6 interposed therebetween to form the capacitor element 8. Further, an anode lead 9 as an anode terminal and a cathode lead 10 as a cathode terminal are bonded to the outer end portion of the tantalum wire 3 protruding from the tantalum sintered body 2 and the cathode layer 7.
The entire part except a part of 10 is covered with a mold made of epoxy resin 11.

As a metal having a valve action, tantalum,
Metals such as aluminum and niobium can be used.
In the case of tantalum, it is used in the form of pellets in which fine powder is sintered and tantalum wire 3 serving as an anode is attached to a tantalum porous body. The cathode layer 7 is formed by applying a silver paste and baking it. The anode lead 9 is connected to the tantalum wire 3 by a resistance welding method, and the cathode lead 10 is connected to the cathode layer 7 via the conductive paste 12.

Such a tantalum solid electrolytic capacitor 1
In order to manufacture, the tantalum fine powder provided with the tantalum wire 3 (particle size: about 30 μm) is compression-molded, and the tantalum fine powder is heated to a predetermined temperature (1
A porous tantalum sintered body 2 is produced by adding (about 700 ° C.) and sintering in a vacuum. Next, the dielectric layer 4 is formed on the surface of the tantalum sintered body 2 by anodic oxidation. As shown in FIG. 7, this anodic oxidation is performed by previously welding the outer end portion of the tantalum wire 3 to a strip plate 15 made of a metal such as stainless steel or aluminum and suspending the tantalum wire 3 to obtain the tantalum sintered body 2.
Is immersed in an electrolytic solution 16 made of an acid solution of nitric acid, phosphoric acid, acetic acid, oxalic acid, etc., and a voltage of several V to several tens of V is applied by using the strip plate 15 as an anode and the electrolytic solution 16 as a cathode.

Next, the tantalum sintered body 2 having the dielectric film 4 formed thereon is impregnated with manganese nitrate solution and adhered thereto, and then 200
Manganese dioxide layer which is a solid electrolyte layer by heating at ~ 350 ° C to deposit manganese dioxide on the dielectric film 4 and repeating manganese nitrate solution impregnation, adhesion and thermal decomposition operations several times or ten or more times. 5 is formed.

Next, a carbon paste is applied and dried to form a carbon layer 6. Further, a conductive silver paste is applied on it and dried to form a cathode layer 7, whereby a capacitor element 8 is manufactured. Thereafter, as shown in FIG. 8, the tantalum wire 3 is cut by the cutting device 17 to separate the capacitor elements 8 from the strip plate 15 one by one. Next, the tantalum wire 3 and the cathode layer 7 are connected to the anode lead 9 and the cathode lead 10.
6 which is a material of the lead frame 13 shown by a chain double-dashed line in FIG.
, And the entire capacitor element 8 is molded with a thermosetting synthetic resin 11 by a transfer molding method. At this time, the protruding end portion of the tantalum wire 3 is cut down to about 1 mm or less in order to reduce the external dimensions of the product. Then, the lead frame 13 protruding to the outside of the synthetic resin 11 is separated to form the anode lead 9 and the cathode lead 10, and the projecting end portions of these both leads 9 and 10 are bent into a predetermined shape. The type capacitor 1 is completed.

In FIG. 8, reference numeral 18 is a guide rail that supports the strip plate 15, and 19 is a chuck that holds the capacitor element 8 by suction. Also, cutting the tantalum wire 3,
Operations such as bending, joining, separation of the lead frame 13 and bending of the anode lead 9 and the cathode lead 10 are continuously performed by one anode lead welding device.

[0008]

As described above, when manufacturing the sintered capacitor 1, the tantalum wire 3 is cut, the lead frame 13 is bent, joined, separated, and the anode lead 9 and the cathode lead 10 are bent. Is continuously performed by one anode lead welding device. However, this welding device is generally a dedicated machine for each size,
There is a problem that it cannot be commonly used for products of various sizes. The reason is that the welding position, height, width of the lead frame, etc. are different for each product of various sizes, and it takes time to replace the frame guide, the press machine, and the adjustment work. Therefore, not only the number of devices increases,
The operating rate of each device varies.

Further, the tantalum wire 3 is attached to the lead frame 13
When resistance welding is performed on the lead frame 13, it is necessary to bend the cathode-side connecting end portion 13a of the lead frame 13 downward into an L-shape and place the capacitor element 8 thereon during welding. When carrying along
Due to poor stability, transport problems are likely to occur and the operating rate of the device is low. Also, the tantalum wire 3 is attached to the lead frame 13.
When resistance welding is performed, heat is used, but when high heat is transmitted to the tantalum sintered body 2 through the tantalum wire 3, the dielectric film 4 is damaged and the leakage current of the capacitor increases.

Therefore, as a result of various studies on the shape of the lead frame 13, the frame guide, the welding method, etc., if the frame guide is provided so as to be vertically movable, it can be applied to products of various sizes, and can be used for general purposes. It has been found that the device can be made highly flexible. Further, when welding the tantalum wire, laser welding can be adopted by bending the anode-side connecting end 13a upward instead of bending the cathode-side connecting end 13a of the leadframe 13 downward. It has been found that can be transported in a stable state. Also, if the frame guide is made of a material with high thermal conductivity and the heat during welding is released to the frame guide via the lead frame, the thermal effect is small even if the welding point is close to the tantalum sintered body, and the capacitor It was found that the leakage current of can be reduced. Further, it was also found that when the lead frame is attracted to the frame guide, variations in thermal influence are reduced. Further, in order to commonly use the capacitors of several sizes, it is necessary to replace the die of the lead frame press machine. On the other hand, the die may be a die-set type and can be replaced with one touch.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is that it can be commonly used for capacitor elements of various sizes and that the lead frame is in a stable state. An object of the present invention is to provide an anode lead welding device for a sintered capacitor, which is transported by the method of (1) and can reduce the influence of heat during welding.

[0012]

In order to achieve the above object, an anode lead welding apparatus for a sintered type capacitor according to the present invention cuts a tantalum wire from a strip plate to sequentially separate the capacitor elements from the strip plate. In an anode lead welding apparatus for a sintered capacitor, which conveys the capacitor element to a welding position and welds the tantalum wire to the anode side connecting end of the lead frame, the anode lead connecting device of the lead frame is directed upward. The lead frame is installed on a frame guide whose height can be adjusted and held by suction, and the capacitor element is placed on the lead frame and the tantalum wire is laser welded to the bent part. It is characterized by doing. Further, the present invention is characterized in that at least the vicinity of the welded portion of the frame guide is formed of a material having a relatively high thermal conductivity. Further, the present invention is characterized in that a suction hole opened on the upper surface of the frame guide is provided, and the suction hole is connected to a vacuum device. Furthermore, the present invention is characterized in that a contact plate for restricting movement of the lead frame in the width direction is provided on the frame guide.

In the present invention, the height of the frame guide is adjusted to enable welding of tantalum wires of various sizes of capacitor elements. The tantalum wire is laser-welded to the bent portion provided on the anode side connection end of the lead frame. The bent portion of the lead frame makes it unnecessary to bend the cathode-side connecting end portion of the lead frame to which the cathode layer is connected when welding the tantalum wire. The frame guide holds the lead frame by suction and releases heat during welding. This plate regulates the vertical and widthwise movement of the lead frame.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. FIG. 1 is a sectional view of a sintered capacitor manufactured by the anode lead welding apparatus according to the present invention, FIG. 2 is an external perspective view of the anode lead connecting apparatus, FIG.
(B) is a plan view and a front view showing a state of welding the tantalum wire, FIG. 4 is a perspective view of the frame guide, and FIG. 5 is a sectional view of the frame guide. In addition, the same components as those described in the section of the prior art are denoted by the same reference numerals, and the description thereof will be omitted. In FIG. 1, the tantalum wire 3 is laser-welded to the connection side end of the anode lead 9 so as to be orthogonal to this. Therefore, the anode lead 9
A bent portion 9a that is bent downward so as to be orthogonal to the tantalum wire 3 is provided at the connection side end portion of the. On the other hand, the cathode lead 10 includes a straight portion 10A located in the synthetic resin 11 in parallel with the cathode layer 7 and a synthetic resin 11
And an L-shaped bent portion 10B that is protruded from and bent along the outer side surface thereof. Other configurations are the same as those of the conventional sintered capacitor 1 shown in FIG.

Next, the method for manufacturing the above-mentioned sintered capacitor and the anode lead welding apparatus will be described in detail. First,
The capacitor element 8 is manufactured by a usual method. That is, the tantalum fine powder provided with the tantalum wire 3 is compression-molded and sintered at a predetermined temperature to produce the porous tantalum sintered body 2. The protruding end of the tantalum wire 3 provided on the tantalum sintered body 2 is welded to the side end of the strip plate 15 (see FIG. 7). The dielectric layer 4 is formed on the surface of the tantalum sintered body 2 by the anodic oxidation method. A cathode layer 7 is formed on the dielectric layer 4 to produce a capacitor element 8.

The capacitor element 8 with the strip-shaped plate thus manufactured is supplied to the stocker 31 of the anode lead connecting device 30 shown in FIG. Strip plate 15 in stocker 31
Are conveyed one by one to the strip-shaped plate conveying unit 32, and the cutting unit 33
At the cutting device 17 shown in FIG.
The capacitor elements 8 are separated from the strip plate 15 one by one by cutting. The separated capacitor element 8 is
When it is sucked and held by the pellet chuck transport mechanism 34 and transported to the welding position 41, it is placed on the lead frame 13.

The lead frame 13 is made of a strip, and when it is fed from the uncoiler 35, it is bent by a press machine 36 into a desired shape. This bending process is to bend the anode side connection end of the lead frame 13, and as a result, as shown in FIGS. 3 and 5, a bent portion 13b bent upward at a substantially right angle is provided. The press machine 36 uses a die set die, and is exchangeable so that it can be commonly used for various lead frames 13 having different widths and plate thicknesses.

Next, after the conductive silver paste 12 is supplied to the upper surface of the cathode side connecting end portion 13a of the lead frame 13 in the potting portion 37, the lead frame cut portion 3 is formed.
At 8, the grooves for forming the anode lead 9 and the cathode lead 10 are formed at both end portions of the lead frame 13. The lead frame 13 in which the groove is formed is placed on the frame guide 40, moved on the frame guide 40 (described later) by the first and second loaders 39a and 39b, and conveyed to the welding position 41. At the welding position 41, the capacitor element 8 conveyed by the chuck conveying mechanism 34 is placed on the cathode side connecting end portion 13a of the lead frame 13 via the conductive paste 12, and the tip end portion of the tantalum wire 3 is arranged as shown in FIG.
As shown in (a), it is inserted from above into a V-shaped groove 42 provided in the upper end surface of the bent portion 13b. Further, a YAG laser 43 is provided as a laser device at the welding position 41, and the laser beam is guided to a welding position by an optical system 44 to weld the tantalum wire 3 to the bent portion 13b of the lead frame 13.

The output energy of the YAG laser 43 is 1 to 15 J / P. Further, the diameter of the laser beam is set to 0.15 to 1 mm in the welded portion and is controlled to 1 to 3 times the tantalum wire diameter. An optical fiber and a condenser lens are used as the optical system 44. Further, by adding an image observation device, it is possible to observe the welded portion by the laser beam.

When the welding to the lead frame 13 is completed, the capacitor element 8 passes through the discharging portion 46 and then the unloader 4
7 and then the capacitor element 8 is molded with epoxy resin 11 by the transfer molding method.
Finally, the lead frame 13 protruding from the epoxy resin 11 is separated to form individual anode leads 9 and cathode leads 10, and the projecting end portions are further bent along the outer surface of the synthetic resin 11 into a predetermined shape. The manufacture of the sintered capacitor 1 shown is completed.

A frame guide 40 for transporting the lead frame 13 to the welding position 41 is a shallow bottom box-shaped main body 40A formed long in the transport direction of the lead frame 13, as shown in FIGS. An upper plate 40B that hermetically covers the upper surface of the main body 40A and a contact plate 57 fixed to one edge of the upper plate 40B by a set screw 56 are provided. The inside of the main body 40A is connected to a vacuum device 59 by a movable pipe 58. Also, the main body 40
A is configured to be moved up and down by a drive motor 60. The upper plate 40B is made of a material having a high thermal conductivity, specifically, 11 W / mK or more, and the upper surface thereof forms the sliding surface of the lead frame 13, and a plurality of suction members that communicate with the inside of the main body 40A. It has a hole 61. The reason why it is made of a material having a high thermal conductivity is that the heat at the time of welding is released to the frame guide 40 side through the tantalum wire 3.
When the thermal conductivity is 11 W / mK or less, the heat dissipation effect is small, which is not preferable. However, as the upper plate 40A,
Not only is the whole made of a material with high thermal conductivity,
The vicinity of the welded portion may be made of a material relatively higher than the other portions. The lead frame 13 has a bent portion 1
When it is conveyed on the frame guide upper plate 40B with 3b facing upward and is conveyed to the welding position, the main body 4 is moved by the vacuum device 59.
By depressurizing the inside of 0A, it is suction-held on the upper plate 40B.

Side wall portions 6 are formed on both sides of the upper surface of the upper plate 40B.
2, 63 are integrally projected, and on the other hand, for example, the inner side surface of the side wall portion 62 forms a reference surface for the lead frame 13. Further, a groove 64 into which the end portion of the lead frame 13 is inserted is formed in the lower portion of the inner side surface of the side wall portion 62. The other side wall portion 63 is used as a fixing portion for the contact plate 57. The contact plate 57 covers the end portion of the lead frame 13 on the side opposite to the side wall portion 62 side, thereby restricting the movement of the lead frame 13 in the width direction and the groove 64 together with the groove 64. Therefore, a groove 67 having a depth substantially equal to the plate thickness of the lead frame 13 is formed on the lower surface of the contact plate 57. in this case,
Since the width of the lead frame 13 varies depending on the size of the capacitor, if various abutting plates 57 having different widths of the grooves 67 are prepared, the frame guide 40 is commonly used for the various lead frames 13. can do. Also,
Since the height of the frame guide 40 is adjusted by driving the drive motor 60 as described above, the frame guide 40 can be commonly used for capacitors of various sizes. That is, the height of the tantalum sintered body 2 differs depending on the size of the capacitor. Therefore, when the capacitor element 8 is placed on the frame 13, the height from the upper surface of the lead frame 13 to the tantalum wire 3 is also different. Therefore, the height of the frame guide 40 is adjusted according to the size of the tantalum element 8, and the tantalum wire 3 is adjusted.
Adjust the welding position of to the focal position of the laser beam.

As described above, in the present invention, the bent portion 13b bent upward is provided at the anode side connection end of the lead frame 13, and the laser welding is performed so that the tantalum wire 3 is orthogonal to the bent portion 13b. Therefore, it is not necessary to bend the cathode-side connecting end portion 13a of the lead frame 13 downward, and the lead frame 13 can be conveyed in a stable state.

Further, in the present invention, since the frame guide 40 is provided so as to be movable up and down, it is possible to cope with capacitor elements having different sizes and the versatility of the apparatus can be improved. In that case, since the width of the lead frame 13 also differs depending on the size of the capacitor element 8, the contact plate 57 having different lengths of the grooves 67 may be replaced according to the lead frame. Further, since the upper plate 40B is made of a material having a high thermal conductivity, it is possible to effectively dissipate heat during welding and reduce the influence on the capacitor element 8. Therefore, the leakage current of the capacitor can be reduced. Further, since the inside of the frame guide 40 is decompressed and the lead frame 13 is sucked and held on the upper surface of the upper plate 40B, the lead frame 13 can be securely fixed at a predetermined position, and the lead frame 13 The close contact with the upper surface of the upper plate 4B can reduce the variation in heat during welding.

Further, since the die of the press machine 36 is a die set type and it can be exchanged with various dies according to the size of the capacitor element 8, the apparatus can be used as a general-purpose machine. Further, during welding, when the laser beam is moved by the position adjusting mechanism in the direction orthogonal to the transport direction of the lead frame 13 and in the vertical direction and the focus position is observed by the image observation device,
It is possible to weld a predetermined welding spot more accurately. Further, it was found that the defect occurrence rate becomes smaller when the YAG laser light of 1 to 15 J / P is used.

The present invention will be described in more detail below with reference to examples.

【Example】

Example 1 A capacitor element having a rated voltage of 10 V and an electrostatic capacity of 1 to 100 μF was manufactured using the four types of porous tantalum sintered bodies 2 shown in Table 1, and the capacitor element was used as a lead frame using the above-mentioned anode lead welding apparatus. Installed on top, laser welding the tantalum wire to the lead frame and connecting the cathode layer to the lead frame 13 via a conductive paste, and after covering the capacitor element with synthetic resin, cutting the lead frame to cut the anode lead and cathode. Using the lead as a lead, a sintered capacitor as shown in FIG. 1 was manufactured. The lead frame is preliminarily bent using a die-set type die according to the size of the capacitor element, and thereby the bent portion 13b having the groove 42 is integrally provided at the anode-side connection end portion. The width of the lead frame 13 is 15 mm and 20 mm.
Although the one of 16 mm was used, a contact plate 57 for a width of about 4 mm was attached on the upper plate 40B when conveying a 16 mm one. In addition, a material having a high thermal conductivity, such as 1.5Fe-0.8Co-0.6Sn-9, is provided near the welded portion of the upper plate 40B.
Made of 7Cu alloy. The frame guide 40 was lowered by the drive motor 60 at a maximum of 0.65 mm. The fine adjustment of the focal position of laser irradiation is performed by the position adjusting mechanism of the laser device, and after the focus is aligned with the welded portion, the position adjusting mechanism is locked by the locking mechanism. The laser output was set at an appropriate value depending on the thickness of the tantalum line as shown in Table 1. Laser welding of tantalum wire was performed on 2000 capacitors of each capacitor element, and appearance inspection of the welded portion was carried out.

[0027]

[Table 1]

Example 2 1.3 × 2,2 provided with a tantalum wire having a diameter of 0.25 mm
Rated voltage 1 using a tantalum sintered body of mm x 2.6 mm
A capacitor element having 0 V and a capacitance of 22 μF was manufactured.
Using the anode lead welding apparatus shown in FIG. 2, the capacitor element was made of the materials shown in Table 2 in the vicinity of the welded portion of the frame guide 40, laser-welded for each 1000 pieces, and then covered with a synthetic resin. The defect occurrence rate at this time is shown in Table 2. It was found that the laser welding using a frame guide made of a material having a low thermal conductivity has a large leakage current and often causes defective products. The laser output was 2.2 J / P, and welding was performed so that the interval between the tantalum sintered body and the welded portion of the tantalum wire was 0.5 mm.

[0029]

[Table 2]

Example 3 Using the same capacitor element as in Example 2 and using the anode lead welding apparatus shown in FIG. 2, 1000 capacitors were produced in the same manner as in Example 2. The material of the frame guide near the weld was made of silicon carbide ceramics. When the capacitor element was not adsorbed on the upper surface of the frame guide that conveys the lead frame, as shown in Table 3, the defect occurrence rate increased.

[0031]

[Table 3]

[0032]

As described above, in the anode lead welding apparatus for a sintered capacitor according to the present invention, the tantalum wire is cut from the strip plate to sequentially separate the capacitor elements from the strip plate, and the capacitor element is welded. In the anode lead welding apparatus for a sintered type capacitor, which conveys the tantalum wire to the position and welds the tantalum wire to the anode-side connecting end of the lead frame, a bend bent upward to the anode-side connecting end of the lead frame. Since the lead frame is installed on a frame guide whose height is adjustable and held by suction, the capacitor element is placed on the lead frame and the tantalum wire is laser-welded to the bent portion. It is possible to weld various capacitors with different sizes with one device, and the device can be used as a general-purpose machine.

Further, according to the present invention, since at least the vicinity of the welded portion of the frame guide is made of a material having a relatively high thermal conductivity, heat during welding can be effectively dissipated.
Therefore, the occurrence of characteristic defects is small. Further, since the lead frame is suction-held and brought into close contact with the upper surface of the frame guide, the heat-dissipating effect is high, variation in temperature distribution is small, and the defect occurrence rate can be further reduced. Further, in the present invention, since the frame guide is provided with the contact plate, the lateral movement of the lead frame can be reliably prevented.

[Brief description of drawings]

FIG. 1 is a sectional view of a sintered capacitor manufactured by an anode lead welding apparatus according to the present invention.

FIG. 2 is an external perspective view of the welding apparatus.

3A and 3B are a plan view and a front view showing how a tantalum wire is welded to a lead frame.

FIG. 4 is a perspective view of a frame guide.

FIG. 5 is a sectional view of the frame guide.

FIG. 6 is a sectional view showing a conventional example of a sintered capacitor.

FIG. 7 is a perspective view showing a process of oxidizing a tantalum sintered body.

FIG. 8 is a diagram showing a step of cutting a tantalum wire.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sintered capacitor, 2 ... Tantalum sintered body, 3 ... Anode lead tantalum wire, 4 ... Dielectric layer, 5 ... Manganese dioxide layer, 6 ... Carbon layer, 7 ... Cathode layer, 8 ... Capacitor element, 9 ... Anode lead, 9a ... Bent portion, 10 ... Cathode lead, 11 ... Epoxy resin, 12 ... Conductive paste, 13
... lead frame, 13a, 13b ... bent portion, 15 ... strip plate, 40 ... frame guide, 57 ... contact plate, 59 ... vacuum device, 60 ... drive motor, 61 ... suction hole.

Claims (4)

[Claims] 1. A tantalum wire is cut from a strip plate to sequentially separate a capacitor element from the strip plate, the capacitor element is conveyed to a welding position, and the tantalum wire is welded to an anode side connection end of a lead frame. In an anode lead welding device for a sintered capacitor, a bent portion bent upward is provided at the anode side connection end of the lead frame, and the lead frame is installed on a height-adjustable frame guide. An anode lead welding apparatus for a sintered capacitor, which is held by suction, and the capacitor element is placed on a lead frame and a tantalum wire is laser-welded to the bent portion. 2. The sinter type capacitor anode lead welding apparatus according to claim 1, wherein at least the vicinity of the welded portion of the frame guide is formed of a material having a relatively high thermal conductivity. Anode lead welding equipment. 3. The anode lead welding apparatus for a sintered capacitor according to claim 1 or 2, wherein a suction hole opened on the upper surface of the frame guide is provided, and the suction hole is connected to a vacuum device. Anode lead welding equipment for sintered capacitors. 4. The sinter type capacitor anode lead welding apparatus according to claim 1, wherein a contact plate for restricting movement of the lead frame in the width direction is provided on the frame guide. Anode lead welding equipment for bonded capacitors.