Metal working – Barrier layer or semiconductor device making – Barrier layer device making
Reexamination Certificate
2001-10-10
2004-05-11
Nguyen, Ha Tran (Department: 2812)
Metal working
Barrier layer or semiconductor device making
Barrier layer device making
C361S502000, C361S505000, C361S520000
Reexamination Certificate
active
06733544
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to coin (button)-type electric double layer capacitors utilizing a lithium ion-conductive non-aqueous electrolyte and comprising a substance capable of occluding and discharging lithium, metallic lithium, or an alloy thereof as a negative active material, and a substance capable of occluding and discharging lithium as the positive active material. The present invention also relates to an electric double layer capacitor mountable by reflow a soldering and to a method of producing the same.
2. Prior Art
Because coin (button)-type electric double layer capacitors are lightweight and are capable of yielding high energy density, their application to back-up power sources of electric appliances has been increasing.
In case of using the capacitor above mainly as the memory back-up power source, in general, a terminal for use in soldering is welded to the capacitor, and the capacitor is then mounted on a printed circuit board together with a memory device by soldering. Conventionally, soldering to the printed circuit board had been realized by using a solder iron, however, with the recent demand on miniaturized devices or on devices with higher function, there is a requirement to increase the number of electronic components to be mounted in a same area of a printed circuit board. Accordingly, more difficulties are found to obtain a space for inserting the solder iron. Furthermore, to reduce the cost, automated soldering operation is required.
Thus, recently employed are a method comprising mounting the components on the printed circuit board the portions of which are previously coated with a solder cream and the like, or a method comprising mounting the components and then supplying small solder balls thereto. In both methods, the printed board having the components mounted thereon is passed through a heating furnace provided with a high temperature atmosphere set at a temperature not lower than the melting point of the solder, for instance, in a temperature range of from 200 to 260° C., such that the solder may be molten to effect the soldering (this method is referred to hereinafter as “reflow soldering”).
3. Problems that the Invention is to Solve
A coin (button)-type electric double layer capacitor mountable by reflow soldering utilizes an organic solvent for the electrolyte, a metallic oxide for the positive electrode, and a negative electrode having added thereto lithium in some form during the production process to provide the active material. In such a capacitor, the constituents incorporated therein are active by nature of the capacitor itself. Accordingly, if the quantity ratio of the constituents should change depending on the fluctuation in the production process, such a change could cause bulging, liquid leakage (i.e., leaking of the electrolyte to the outside of the capacitor), etc., during the reflow soldering utilized in mounting the capacitor to the product board.
Furthermore, an electric double layer capacitor mountable by reflow soldering must assure the capacitor performance after reflow soldering. However, there are some cases in which the capacitor contains somewhat large amount of foreign matter (i.e., water, etc.). The capacitor characteristics are not influenced at the room temperature, but after reflow soldering or after storage, a sudden deterioration in capacitor characteristics was sometimes found to occur in such cases.
SUMMARY OF THE INVENTION
As a means of overcoming the aforementioned problems, the present invention according to a first aspect provides, in a method for producing an electric double layer capacitor comprising a positive electrode, a negative electrode, a non-aqueous solvent, an electrolyte containing a supporting salt, a separator, and a gasket, a method comprising: a step of assembling by caulk sealing inside an electric double layer capacitor said positive electrode, said negative electrode, said non-aqueous solvent, said electrolyte, said separator, and said gasket; and a heating step. In this aspect, an outer connection terminal may be welded after the heating. The heating temperature can be set in a range of from 180 to 300°C. However, the upper limit of the temperature must be set at a temperature not higher than the melting point of the material constituting the gasket used in the product.
In accordance with a second aspect of the present invention, there is provided, in a mounting method comprising arranging an electric double layer capacitor on a circuit substrate, a mounting method which comprises a step of assembling by caulk sealing inside an inner electric double layer capacitor said positive electrode, said negative electrode, said non-aqueous solvent, said electrolyte, said separator, and said gasket; a heating step; and a step of arranging and reflow soldering said electric double layer capacitor on said circuit substrate. In this case, an outer connection terminal may be welded after the assemblage. Furthermore, preferably, in the heating region of from 0 to 150° C., the difference between the temperature profile with respect to time during said heating step and the temperature profile with respect to time during said reflow soldering falls within ±50%.
Also preferably, in the heating region of from 0 to 150°C., the difference in time duration between the time of said heating step and the time of said reflow soldering falls within
It is also preferred that, in the heating region of from 150 to 180° C., the difference between the temperature profile with respect to time during said heating step and the temperature profile with respect to time during said reflow soldering falls within ±20%.
Further preferably, in the heating region of from 150 to 180° C., the difference in time duration between the time of said heating step and the time of said reflow soldering falls within ±20%.
Also preferably, in the heating region of from 180 to 300° C., the difference between the temperature profile with respect to time during said heating step and the temperature profile with respect to time during said reflow soldering falls within ±10%.
It is also preferred that, in the heating region of from 180 to 300° C., the difference in time duration between the time of said heating step and the time of said reflow soldering falls within ±10%.
In accordance with another aspect of the present invention, there is used a sealing material for an electric double layer capacitor comprising a rubber based adhesive provided with asphalt on the surface thereof. Preferably, the sealing material is provided on the surface of said rubber based adhesive in a plurality of spots set apart from each other.
Also preferably, said asphalt is a fraction obtained by heating crude oil. Furthermore, it is preferred that the rubber based adhesive contains asphalt inside thereof.
Further preferably, the asphalt accounts for 1% or more but not more than 50% of said rubber based adhesive. More preferably, the asphalt accounts for 5% or more but not more than 20% of said rubber based adhesive.
It is also preferred that the asphalt is a blown asphalt or a straight asphalt.
Suitably used as the rubber based adhesive is such based on butyl rubber.
According to a still other aspect according to the present invention, there is used a sealing material for an electric double layer capacitor obtained by mixing asphalt with a rubber based adhesive and by then heating the resulting mixture.
Furthermore according to another aspect of the present invention, there is employed a method for producing a sealing material for an electric double layer capacitor, which comprises mixing asphalt with a rubber based adhesive, and by then heating the resulting product. Preferably, rubber based adhesive is based on butyl rubber. Furthermore, the mixing is carried out in an organic solvent. It is further preferred that the organic solvent is toluene.
In accordance with an aspect of the present invention, there is provided a method for producing an electric double laye
Kanno Yoshimi
Nakamura Yoshibumi
Onodera Hideharu
Sakai Tsugio
Takasugi Shinichi
Adams & Wilks
Nguyen Ha Tran
SII Micro Parts Ltd.
LandOfFree
Method of producing electrical double layer capacitor and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of producing electrical double layer capacitor and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of producing electrical double layer capacitor and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3210590