Electricity: electrical systems and devices – Electrostatic capacitors – Fixed capacitor
Patent
1991-01-28
1992-12-01
Griffin, Donald A.
Electricity: electrical systems and devices
Electrostatic capacitors
Fixed capacitor
29 2542, H01G 408, H01G 700
Patent
active
051684217
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a film capacitor and a process for producing it. More particularly, the present invention relates to a film capacitor suitable to use for so-called chip capacitors of the surface mounting type, and a process for producing it.
BACKGROUND OF THE INVENTION
Recently, electronic parts such as capacitors have been required to be small-sized, accompanying with miniaturization of electronic equipments. Accordingly, respect to film capacitors, so-called chip capacitors applicable with surface mounting have been developed. So-called stacking type film capacitors, wherein substantially planar and rectangularly cut dielectric films and electrodes such as deposited metal layers are stacked, are particularly favorable for miniaturization. In such a small-sized stacking type film capacitor, since usually a thin film is used as its dielectric film, the capacitance generating portion of the capacitor is likely to be injured. Therefore, a protective layer formed by stacking thick films or sheets is provided on the outer side of the capacitance generating portion of the conventional film capacitor in order to protect the capacitance generating portion. In a chip capacitor, however, although a high thermal resistance for soldering is required for the protective layer because the capacitor is soldered directly to a printed circuit board, a protective layer having an excellent thermal resistance cannot be obtained by the conventional process wherein the protective layer is formed by stacking thick films or sheets.
In more detail, it is considered that a film having a high thermal resistance such as a heat sticking type polyimide film or a biaxially oriented polyphenylenesulfide film is used to form a protective layer having a high thermal resistance. However, there are defects in the polyimide film that the film is expensive and has a poor chemical resistant property, the deterioration of the film due to hydrosis under a high moist condition quickly occurs, and the dimensional stability of the film against moisture is poor. As a result, the environment for use of the film is restricted. In ordinary biaxially oriented polyphenylenesulfide films, according to the investigation by the inventors of the present invention, the films are easily delaminated between the film layers because the adhesive property between the film layers is not good. Therefore, a practical protective layer cannot be obtained. Further, although it is considered that a film, in which an adhesive is applied onto or a layer having an adhesive property is provided on a biaxially oriented polyphenylenesulfide film, is used (for example, JP-A-SHO 64-77910), a process for applying the adhesive must be added, and the process for producing the capacitors becomes complicated by the application process. Moreover, because the biaxially oriented polyphenylenesulfide film slightly shrinks accompanying with a large shrinkage stress when the film is heated such as when the capacitor is attached, if a usual adhesive is used, the deformation or delamination of the protective layer occurs, for example, when the capacitor is dipped in a molten solder. Therefore, a practical protective layer also cannot be obtained.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a film capacitor which has excellent thermal resistance, chemical resistance and stability against moisture and has a protective layer capable of simplifying the sticking process or omitting an adhesive layer, and a process for producing it.
To accomplish this object, a film capacitor according to the present invention has a protective layer on at least a part of the outer surface of a capacitance generating portion constructed from the layers of a dielectric film and electrodes, and is characterized in that at least a part of the protective layer is a substantially non-oriented film consisting of polyphenylenesulfide.
In processes for producing the film capacitor according to the present invention, there are two proce
REFERENCES:
patent: 3585468 (1971-06-01), Chertok et al.
patent: 3806775 (1974-04-01), Edman
patent: 4578737 (1986-03-01), Westermann
patent: 4672506 (1987-06-01), Deguchi et al.
Deguchi Yukichi
Suzuki Motoyuki
Griffin Donald A.
Miller Austin R.
Toray Industries Inc.
LandOfFree
Film capacitor and process for producing it does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Film capacitor and process for producing it, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Film capacitor and process for producing it will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-506683