JP2005183665A - Metallized film capacitor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the bumping of a second electrode layer when the sheath-less surface-mounting metallized film capacitor undergoes lead-free reflow soldering, to eliminate bad external appearance; and to improve moisture resistance. <P>SOLUTION: A metallized film capacitor and its manufacturing method are configured in such a way that a capacitor element is formed by winding in layers a later winding plastic film on an element on which a pair of metallized films is wound. After the first electrode layer of an electrode lead is formed on opposite end surfaces of the capacitor element, a second electrode layer is formed and an external electrode is mounted. Herein, the second electrode layer is formed after the first electrode layer is formed, impregnated in resin, and hardened. The foregoing resin is epoxy resin or silicone resin of 1 to 1000 mPa s viscosity, and the first electrode layer is constituted by any of an alloy consisted of 60 to 70 % copper and remaining zinc, an alloy consisted of 40 to 56 % aluminum, ≥4% silicon, and ≥40% zinc, an alloy consisted of ≥90 % zinc and remaining aluminum, and single zinc. The second electrode layer is consisted of ≥80% tin and remaining zinc and copper. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a metallized film capacitor of an exterior-less surface mounting type, and more particularly to a metallized film capacitor having excellent current resistance characteristics and improved solder heat resistance, and a method for manufacturing the same.

  Conventionally, a surface mount type metalized film capacitor has been known to have a flat element structure (see, for example, Patent Document 1).

JP 2000-58369 A (page 2-6, FIG. 3, FIG. 5, FIG. 7)

In the flat type film capacitor, a capacitor film is formed by stacking and winding a plastic film for subsequent winding on an element in which a pair of metallized films are wound and stacked, and a first electrode lead portion is formed on both end faces of the capacitor element. After sequentially forming the electrode layer and the second electrode layer, the resin is vacuum impregnated (or ultrasonically impregnated), the excess resin is removed, and after heat curing, an external electrode is attached and configured.
In recent years, lead-free solder has been promoted due to environmental problems. However, general lead-free solder has a higher melting temperature than conventional lead-containing solder, and metalized film capacitors are required to have improved heat resistance. Yes.
However, in the metallized film capacitor, a low melting point metal is used for the second electrode layer in order to improve the bondability with the external electrode. However, when lead-free solder reflow is performed at 260 ° C. for 10 seconds, the second electrode layer The resin impregnated in is thermally expanded and the metal of the second electrode layer, which has been in a semi-molten state, is pushed out to a bumping state, which deteriorates the appearance and moisture resistance of the metallized film capacitor. It was.

The present invention solves the above-mentioned problem, and there is no bumping from the second electrode layer of the metallized film capacitor even in lead-free solder reflow at 260 ° C. for 10 seconds, etc., and the metallized film with improved moisture resistance A capacitor is provided.
That is, after a pair of metallized films is wound around a plastic film for subsequent winding to form a capacitor element, and after forming the first electrode layer of the electrode lead portion on both end faces of the capacitor element, In the metallized film capacitor for forming the second electrode layer and attaching the external electrode, and the manufacturing method thereof,
A metallized film capacitor and a method of manufacturing the same, wherein a second electrode layer is formed after forming a first electrode layer, impregnating with resin, and curing.

  The metallized film capacitor is characterized in that after the first electrode layer is formed, the resin to be impregnated is an epoxy resin or a silicone resin having a viscosity of 1 to 1000 mPa · s.

  Further, the first electrode layer is made of an alloy composed of 60 to 70% residual zinc of copper, an alloy composed of 40 to 56% aluminum, 4% or more of silicon and 40% or more of zinc, an alloy composed of residual aluminum containing 90% or more of zinc, The metallized film capacitor is composed of any one of zinc alone, and the second electrode layer is composed of 80% or more of tin and remaining zinc and copper.

  A metallized film capacitor is characterized in that the first and second electrode layers are formed by metal spraying.

  Further, the present invention is a metallized film capacitor using a plate-like terminal as the external electrode.

  The metallized film capacitor of the present invention is formed of a low melting point metal after forming a first electrode layer made of a high melting point metal on both end faces of the capacitor element, then impregnating the resin, removing excess resin and curing it. By providing the second electrode layer, the second electrode layer is not impregnated with resin. Therefore, even if the second electrode layer is in a semi-molten state due to the lead-free solder reflow, the metal is not bumped, and the external terminal It is possible to prevent the appearance failure and further improve the moisture resistance without deteriorating the bonding property.

A capacitor film 3 is formed by overlappingly winding a film for subsequent winding on an element in which a pair of metallized films are wound, and a first electrode layer 4a of an electrode lead portion is formed on both end faces of the capacitor element 3 to form a resin. After impregnating and curing, the second electrode layer 4b is formed. The resin impregnation after the formation of the second electrode layer 4b is not performed.
Here, the first electrode layer is made of an alloy composed of 60 to 70% residual zinc of copper, an alloy composed of 40 to 56% aluminum, 4% or more of silicon and 40% or more of zinc, an alloy composed of residual aluminum containing 90% or more of zinc, zinc The second electrode layer is composed of 80% or more of tin and residual zinc and / or copper.
Moreover, after forming the first electrode layer, the resin to be impregnated is an epoxy resin or a silicone resin.

Next, an embodiment of the present invention will be described with reference to FIGS.
[Examples 1-1 to 1-4]

FIG. 1 is a sectional view of a capacitor element according to an embodiment of the present invention. A pair of metallized films 1 deposited with aluminum on a dielectric film PPS (polyphenine sulfide) were overlapped and wound, and a PPS film for subsequent winding was wound a plurality of times to form a capacitor element 3.
Next, the first electrode layer 4a (thickness 0.15 mm) of the electrode lead portion was formed by spraying the metal shown in Table 1 on both end faces of the capacitor element 3 respectively.

  This capacitor element was impregnated with a liquid epoxy resin having a viscosity of 800 mPa · s at a degree of vacuum of 100 kPa or less, and after removing the excessively adhered resin, the resin was heated at 110 ° C. for 3 hours to cure the resin.

After the resin was cured, heat treatment was performed at 180 ° C. for 4 hours, and metal spraying of 89% tin, residual zinc, and copper was performed on the first electrode layer 4a to form a second electrode layer 4b having a thickness of 0.25 mm.
Then, after the formation of the second electrode layer 4b, resin impregnation was not performed, and the plate-like terminal of FIG. 4A was attached as an external electrode by resistance welding.
A capacitor of 100 VDC and 0.1 μF was produced as described above.

(Conventional examples 1-1 to 1-4)
Similarly to the above example, the capacitor element 3 was formed, and the metal shown in Table 1 was sprayed on both end faces thereof to constitute the first electrode layer 4a of the electrode lead portion.

  Thereafter, the second electrode layer 4b is formed of 89% tin, residual zinc, and copper, impregnated with a liquid epoxy resin having a viscosity of 800 mPa · s at a vacuum degree of 100 kPa or less, and after removing the excessively adhered resin, the second electrode layer 4b is formed at Heated for hours to cure the resin.

A plate-like terminal shown in FIG. 4A was attached to the capacitor element as an external electrode by resistance welding.
A capacitor of 100 VDC and 0.1 μF was produced as described above.

(Comparative Examples 1-1 to 1-4)
Similarly to the above embodiment, after the capacitor element formation and the first electrode layer 4a and the second electrode layer 4b are formed, the resin-impregnation is not performed, and the plate-like terminal of FIG. Attached by.

For Examples 1-1 to 1-4, Conventional Examples 1-1 to 1-4, and Comparative Examples 1-1 to 1-4, lead-free solder reflow was performed at 260 ° C. for 10 seconds, and 60 ° C. A 95% humidity resistance test was conducted for 2000 hours to measure the characteristics. Here, the number of samples was 10 each.
The results are shown in Table 1.

As is clear from Table 1, in Examples 1-1 to 1-4 in which the first electrode layer was formed and the epoxy resin was impregnated and the second electrode layer was not impregnated with the resin, the reflow soldering was performed. After the attachment, there is no bumping of the second electrode layer, and the change in capacitance and tan δ after the moisture resistance test is small and stable.
On the other hand, in the conventional examples 1-1 to 1-4 in which resin impregnation was performed up to the second electrode layer, bumping of the second electrode layer occurred after reflow soldering, and the capacitance and tan δ after the moisture resistance test were changed. Was larger than Examples 1-1 to 1-4.
Further, in Comparative Examples 1-1 to 1-4 in which the first electrode layer and the second electrode layer were not impregnated with resin, bumping did not occur, but the characteristics after the moisture resistance test were significantly deteriorated.
Here, the viscosity of the epoxy resin is suitably 1 to 1000 mPa · s. If it is less than 1 mPa · s, there is a problem that the impregnated resin flows out. If it exceeds 1000 mPa · s, the impregnation rate decreases.
The alloy composition of the first and second electrode layers is set as described above in consideration of the corrosion resistance, solderability, and cost of the metal material.

[Examples 2-1 to 2-4]
Capacitor elements were produced in the same manner as in Examples 1-1 to 1-4, and the first electrode layer 4a (thickness 0.15 mm) was configured by spraying the metal shown in Table 2 on both end faces.

  This capacitor element was ultrasonically impregnated with a liquid silicone resin having a viscosity of 20 mPa · s to remove excess resin, and then heated at 110 ° C. for 3 hours to cure the resin.

After the resin was cured, heat treatment was performed at 180 ° C. for 4 hours, and metal spraying of 89% tin, residual zinc, and copper was performed on the first electrode layer 4a to form a second electrode layer 4b having a thickness of 0.25 mm.
Then, after the formation of the second electrode layer 4b, resin impregnation was not performed, and the plate-like terminal of FIG. 4A was attached as an external electrode by resistance welding.
A capacitor of 100 VDC and 0.1 μF was produced as described above.

(Conventional examples 2-1 to 2-4)
Similarly to the above example, the capacitor element 3 was formed, and the metal shown in Table 2 was sprayed on both end faces thereof to constitute the first electrode layer 4a of the electrode lead portion.

Thereafter, the second electrode layer 4b is formed of 89% tin, residual zinc and copper, impregnated with a liquid silicone resin having a viscosity of 20 mPa · s at a vacuum degree of 100 kPa or less, and after removing the excessively adhered resin, the second electrode layer 4b is removed at 110 ° C. Heated for hours to cure the resin.
A plate-like terminal shown in FIG. 4A was attached to the capacitor element as an external electrode by resistance welding.
A capacitor of 100 VDC and 0.1 μF was produced as described above.

(Comparative Examples 2-1 to 2-4)
Similarly to the above embodiment, after the capacitor element formation and the first electrode layer 4a and the second electrode layer 4b are formed, the resin-impregnation is not performed, and the plate-like terminal of FIG. Attached by.

For Examples 2-1 to 2-4, Conventional Examples 2-1 to 2-4, and Comparative Examples 2-1 to 2-4, lead-free solder reflow was performed at 260 ° C. for 10 seconds, and 60 ° C. A 95% humidity resistance test was conducted for 2000 hours to measure the characteristics. Here, the number of samples was 10 each.
The results are shown in Table 2.

As is clear from Table 2, in Examples 2-1 to 2-4 in which the first electrode layer was formed and then the silicone resin was impregnated, and the resin impregnation after the second electrode layer was not formed was performed in reflow soldering After the attachment, there is no bumping of the second electrode layer, and the change in capacitance and tan δ after the moisture resistance test is small and stable.
On the other hand, in Conventional Examples 2-1 to 2-4 in which resin impregnation was performed up to the second electrode layer, bumping of the second electrode layer occurred after reflow soldering, and the capacitance and tan δ after the moisture resistance test were changed. Was larger than Examples 2-1 to 2-4.
Further, in Comparative Examples 1-1 to 1-4 in which the first electrode layer and the second electrode layer were not impregnated with resin, bumping did not occur, but the characteristics after the moisture resistance test were significantly deteriorated.
Here, the viscosity of the silicone resin is suitably 1 to 1000 mPa · s. If it is less than 1 mPa · s, there is a problem that the impregnated resin flows out, and if it exceeds 1000 mPa · s, the impregnation rate decreases.

  In the above embodiment, a plate-like terminal as shown in FIG. 4A is joined to the second electrode layer as an external electrode. However, when a plate-like terminal as shown in FIGS. 4B and 4C is used. However, as described above, the effects of preventing bumping of the second electrode layer and improving moisture resistance were obtained.

In the above embodiment, the first electrode layer is made of any alloy consisting of 65% copper remaining zinc, 44% aluminum, 6% silicon, 50% zinc alloy, 95% zinc remaining aluminum alloy, and zinc alone. The second electrode layer is composed of 89% tin and the remaining zinc and copper, but the first electrode layer is composed of 60 to 70% copper and 40% to 56% aluminum. The same effect can be obtained if the alloy is composed of an alloy consisting of 4% or more of silicon and 40% or more of zinc, or 90% or more of zinc and remaining aluminum, and the second electrode layer is 80% or more of tin and remaining zinc and / or copper. It is done.
In addition, the method for forming the second electrode layer is effective even in the case of plating or the like, but thermal spraying is preferable, and as the resin, epoxy resin and silicone resin are preferable.
The thickness of the first electrode layer is suitably in the range of 0.1 to 0.2 mm. If the thickness is less than 0.1 mm, the current resistance decreases.
The thickness of the second electrode layer is suitably in the range of 0.2 to 0.3 mm. If it is less than 0.2 mm, the bonding strength with the external electrode is lowered, and if it exceeds 0.3 mm, it is not preferable for miniaturization.
The resin curing conditions are not limited to those in the examples, and can be changed depending on the size of the capacitor element and the resin used.
The metallized film is not limited to PPS, and a known material for depositing aluminum or zinc on polyethylene terephthalate, polyethylene naphthalate, or the like can be used.

It is sectional drawing of the capacitor | condenser element of the metallized film capacitor by the Example of this invention. It is an external view of FIG. It is a figure showing the state which attached the external electrode to the capacitor | condenser element of FIG. It is a figure showing the shape of the plate-shaped terminal attached to the external electrode of FIG. 3, (a) is U-shaped, (b) is C-shaped, (c) is four drum-shaped openings. ing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metallized film 1a Metal vapor deposition part 1b Dielectric film 2 Plastic film for back winding 3 Capacitor element 4a 1st electrode layer 4b 2nd electrode layer 5 External electrode (plate-shaped terminal)
6 Opening 7 Resistance weld

Claims (5)

A capacitor film is formed by overlappingly winding a plastic film for subsequent winding on an element in which a pair of metallized films is wound, and after forming first electrode layers of electrode lead portions on both end faces of the capacitor element, a second In a metallized film capacitor for forming an electrode layer and attaching an external electrode and a manufacturing method thereof,
A metallized film capacitor comprising: forming a first electrode layer; impregnating with resin; curing; and then forming a second electrode layer.   2. The metallized film capacitor according to claim 1, wherein the resin to be impregnated after forming the first electrode layer is an epoxy resin or a silicone resin having a viscosity of 1 to 1000 mPa · s.   The first electrode layer according to claim 1 is an alloy composed of 60 to 70% residual zinc of copper, an alloy composed of 40 to 56% aluminum, 4% or more of silicon and 40% or more of zinc, and an alloy composed of residual aluminum containing 90% or more of zinc. The metallized film capacitor is composed of any one of zinc and the second electrode layer is composed of 80% or more of tin and remaining zinc and copper.   A metallized film capacitor, wherein the first and second electrode layers according to claim 1 are formed by metal spraying.   A metalized film capacitor using a plate-like terminal as the external electrode according to claim 1.

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