JP5550415B2 - Electrochemical cell with terminal and manufacturing method - Google Patents

Description

  The present invention relates to a terminal-equipped electrochemical cell such as a battery having a terminal and a capacitor.

  In conventional electrochemical cells, terminals are attached for the purpose of being soldered to a circuit board. As for welding, spot welding is performed by resistance welding or laser welding (for example, Patent Document 1).

JP-A-62-268055

  The reliability of an electrochemical cell that has terminals attached for the purpose of being soldered to a circuit board and consists of a positive electrode, a negative electrode, a nonaqueous solvent, an electrolyte containing a supporting salt, a separator, a gasket, etc. is sealed. The part which depends on stop is large. In recent years, these electrochemical cells tend to be smaller and thinner due to the demand for smaller equipment. When the electrochemical cell is reduced in size, members constituting the electrochemical cell are also reduced in size. The miniaturized member has a large dimensional tolerance with respect to the size, and there is a problem that the sealing performance is not sufficient unless the management in assembly is made highly accurate.

  In addition, the thin electrochemical cell has a problem that the terminal and the metal case constituting the cell are extremely close to each other and are easily short-circuited. In particular, when the environment contains a lot of humidity, dew condensation occurs between the terminals and the metal case that constitutes the cell, so that there is a problem that rust is generated and a short circuit easily occurs. Further, when the process of soldering to the circuit board is performed using a reflow furnace, an expensive material having high heat resistance must be used as the gasket material.

  The present invention has been made in view of such conventional circumstances, and has an electrochemical cell with a terminal capable of preventing rust and short-circuiting with good sealing performance without making assembly management highly accurate and its manufacture. The purpose is to provide a method.

In order to solve the above problems, the present invention has the following configuration.
The invention of claim 1 is a terminal-attached electrochemical cell having a terminal solderable to a circuit board on the surface, and containing a positive electrode, a negative electrode, a nonaqueous solvent, an electrolyte containing a supporting salt, and a separator. In addition, a polyparaxylylene film formed by CVD is formed on the entire surface of the electrochemical cell with terminals other than the portion in contact with the circuit substrate of the terminals, on the surface opposite to the circuit substrate of the electrochemical cells, The present invention relates to an electrochemical cell with a terminal, characterized in that the surface of a positive electrode can, a gasket and a negative electrode can are continuously covered with the polyparaxylylene film .
According to the first aspect of the present invention, there is provided an electrochemical cell with a terminal having a terminal solderable to a circuit board on the surface, and containing a positive electrode, a negative electrode, a nonaqueous solvent, a supporting salt containing an electrolyte, and a separator. In this case, when soldering to the circuit board, a film formed by CVD is formed in a portion other than the portion in contact with the circuit board of the terminal, thereby improving the sealing performance of the electrochemical cell.
Further, by using a polyparaxylylene film as the film formed by the CVD, a CVD film with good adhesion and few defects can be formed. Further, by using a polyparaxylylene film, a stable CVD film can be maintained even by heating by reflow.

The invention of claim 2 is a terminal-attached electrochemical cell having a terminal solderable to a circuit board on the surface and containing a positive electrode, a negative electrode, a nonaqueous solvent, an electrolyte containing a supporting salt, and a separator. A polyparaxylylene film formed by CVD is formed on the entire surface of the flat electrochemical cell with terminals other than the solder-plated portions of the terminals, and is opposite to the circuit board of the electrochemical cells. The surface of the positive electrode can, the gasket and the negative electrode can are continuously covered with the polyparaxylylene film .
According to the second aspect of the invention, the CVD film can be efficiently formed by having a place where the CVD film is not formed depending on the shape of the terminal.
Further, by using a polyparaxylylene film as the film formed by the CVD, a CVD film with good adhesion and few defects can be formed. Further, by using a polyparaxylylene film, a stable CVD film can be maintained even by heating by reflow.

The invention of claim 3 is the terminal with the electrochemical cell according to claim 1 or 2, before Kipo Riparakishiriren film is characterized in that the poly tetrafluoroethylene-para-xylylene.
According to the invention of claim 3, by forming the film formed by CVD as a polyparaxylylene film, it is possible to form a CVD film with good adhesion and few defects. Further, by using a polyparaxylylene film, a stable CVD film can be maintained even by heating by reflow. Furthermore, polyparaxylylene is more preferable because it is excellent in corrosion resistance, heat resistance, and non-gas permeability.

A fourth aspect of the present invention is the electrochemical cell with a terminal according to any one of the first to third aspects, wherein the polyparaxylylene film has a thickness of 2 μm to 15 μm.
According to invention of Claim 4, a highly durable CVD film can be formed efficiently by the thickness of the said polyparaxylylene film | membrane being 2 micrometers-15 micrometers.

The invention according to claim 5 is the electrochemical cell with a terminal according to claim 1, wherein the terminal has a step.
According to the invention of claim 5, a stable CVD film can be formed by providing a step in the terminal.

Invention of Claim 6 is a manufacturing method of the electrochemical cell with a terminal of Claim 1 or Claim 2, Comprising: It connects with the board | substrate of the electrochemical cell with a terminal on the adhesive sheet-like base | substrate. And a step of forming a polyparaxylylene film by CVD on the electrochemical cell with terminals arranged on the substrate, and a step of arranging the surfaces to be contacted with the substrate. It is related with the manufacturing method.
According to the invention of claim 6, in the state where the electrochemical cell with a terminal is arranged on an adhesive sheet-like substrate in contact with the surface of the electrochemical cell with terminal in contact with the substrate, By introducing it into the CVD apparatus, a polyparaxylylene film can be formed at a portion other than the portion of the terminal that contacts the circuit board when soldering to the circuit board. Thereby, since the polyparaxylylene film is not formed by CVD in the part which contacts the circuit board of a terminal, the soldering to the circuit board of the electrochemical cell with a terminal can be performed easily.

Invention of Claim 7 is a manufacturing method of the electrochemical cell with a terminal of Claim 1 or Claim 2, Comprising: The process of inserting the solder-plated part of the terminal of the electrochemical cell with a terminal in a base | substrate, and standing up, and And a step of forming a polyparaxylylene film by CVD on the electrochemical cell with terminal placed on the substrate, and a method for producing the electrochemical cell with terminal.
According to the seventh aspect of the present invention, the solder-plated portions of the terminals of the electrochemical cell with terminals are inserted into the substrate and arranged in an upright state, and are introduced into the CVD apparatus. A polyparaxylylene film can be formed in a portion other than the portion in contact with the circuit board of the terminal. Thereby, since the polyparaxylylene film is not formed by CVD in the part which contacts the circuit board of a terminal, the soldering to the circuit board of the electrochemical cell with a terminal can be performed easily.

Invention of Claim 8 is a manufacturing method of the electrochemical cell with a terminal of Claim 7, Comprising: The said base | substrate which stood the said electrochemical cell with a terminal has rubber elasticity, and the said base | substrate has the said terminal It is characterized by having a groove or notch for standing the electrochemical cell.
According to invention of Claim 8, the base | substrate which stood the electrochemical cell with a terminal shown by invention of Claim 7 has rubber elasticity, and has a groove | channel or a notch for standing up the electrochemical cell with a terminal. By being a thing, the electrochemical cell with a terminal can be easily stood and arranged in the base | substrate.

  According to the present invention, in a terminal-attached electrochemical cell having a terminal attached for the purpose of being soldered to a circuit board, when soldering to the circuit board, a coating is formed by CVD in addition to the portion of the terminal that contacts the circuit board. Is formed, and the sealing performance of the electrochemical cell is improved. As a result, the deterioration of the electrical characteristics of the electrochemical cell due to the external humidity entering the electrochemical cell is eliminated, and the leakage of the electrolyte solution from the electrochemical cell is eliminated. Furthermore, generation | occurrence | production of the rust of exterior cases, such as a positive electrode can of a electrochemical cell and a negative electrode can, by the humidity of use environment can be suppressed.

  According to the present invention, in a thin electrochemical cell with a terminal, there is a problem that a terminal and a metal case constituting the cell are extremely close to each other and are easily short-circuited. However, a short circuit can be prevented by forming a CVD film.

  In the electrochemical cell with terminals of the present invention, the reliability of the electrochemical cell can be remarkably improved by covering almost all except the soldered portion with the CVD film. Further, by increasing the reliability, the mounting area does not increase and the manufacturing cost does not increase significantly. Further, even when the electrochemical cell with a terminal of the present invention is used for reflow soldering, both reliability and cost are superior to those of the prior art.

It is a side view of the electrochemical cell with a terminal of this invention. It is the figure which looked at the electrochemical cell with a terminal of the present invention from the upper surface. It is a side view of the electrochemical cell with a terminal of this invention. It is a side view of the electrochemical cell with a terminal of this invention. It is the figure which looked at the electrochemical cell with a terminal of the present invention from the upper surface. It is a figure explaining the case where the electrochemical cell with a terminal of this invention is arranged in a base | substrate. It is a figure (enlarged view of the FIG. 1A part) of the film of the electrochemical cell with a terminal of this invention.

  FIG. 1 shows a side view when the electrochemical cell with a terminal of the present invention is mounted on a substrate for forming a CVD film or mounted on a circuit board. FIG. 2 shows a view from above. FIG. 7 shows the state of the CVD film. As shown in FIG. 1, a negative electrode terminal 110 is fixed to the negative electrode can 105 of the electrochemical cell, and a positive electrode terminal 104 is fixed to the positive electrode can 103 by laser welding. Further, solder plating layers 107 and 109 such as tin are disposed on the terminals. As a result, the electrochemical cell with terminal of the present invention is soldered and fixed to the circuit board in contact with the contact surface 106 via the solder plating layers 107 and 109.

  The reliability of an electrochemical cell is improved by how to stop moisture entering the cell. In general, in the coin button type electrochemical cell, moisture enters from between the gasket 108 and the negative electrode can 105 or the positive electrode can 103. For this reason, the caulking seal is precisely controlled when the electrochemical cell is assembled, and a liquid sealant is disposed between the gasket 108 and the negative electrode can 105 or the positive electrode can 103 to prevent moisture from entering. However, these measures alone were not always sufficient.

  Moreover, when attaching an electrochemical cell with a terminal to a circuit board by reflow soldering, the heat of 230-260 degreeC will be added to the electrochemical cell with a terminal. Therefore, even if the caulking seal is precisely controlled when assembling the electrochemical cell, a slight gap is generated due to the difference in thermal expansion coefficient between the plastic gasket 108 and the metal negative electrode can 105 or the positive electrode can 103. In addition, the effect of the liquid sealant may be reduced by heat.

  In the present invention, in order to improve the sealing performance of the electrochemical cell with terminals, a CVD film was formed and the electrochemical cell with terminals was coated.

  In order to form a CVD film, an electrochemical cell with terminals is mounted on a flat substrate as shown in FIG. In order to efficiently form a CVD film with a CVD apparatus, it is preferable to arrange a plurality of films on the contact surface 106 on the substrate and introduce them into the chamber of the CVD apparatus. The substrate is not particularly limited as long as it is flat, but it is preferable that the adhesive film is stretched like a drum skin and arranged on the adhesive surface. It is possible to ensure that the CVD film is not formed on the soldered portion of the terminal, and it is easy to remove it from the substrate after the CVD film is formed.

As shown in FIG. 3, a step 201 is provided on the positive electrode terminal 1041 on the substrate side. Thereby, the formation area of a CVD film increases and it becomes easy to remove from a base | substrate further.
FIG. 4 shows a side view when the electrochemical cell with terminal of another shape of the present invention is mounted on a circuit board. FIG. 5 shows a view from the top.

  In order to form a CVD film, the electrochemical cell 112 with a terminal 112 was inserted into the substrate 113 as shown in FIG. Then, it introduce | transduced in the chamber of CVD apparatus, and formed the CVD film. The substrate 113 preferably has rubber elasticity. If the notch 114 for inserting the back electrode terminal 1042 and the negative electrode terminal 1102 is provided in the base 113 as shown in FIG. 6, the terminal-attached electrochemical cell 112 can be easily held and inserted into the base 113. It is possible to ensure that a CVD film is not formed on the plating layer 1092 corresponding to the soldered portion of the terminal. Moreover, it becomes easy to remove from a base | substrate after formation of a CVD film.

As a coating for the electrochemical cell, a thermosetting resin mold is known. However, in order to improve the sealing property of the electrochemical cell and ensure the reliability, a considerable thickness is required. Therefore, it is not suitable as a coating for electrochemical cells that are becoming smaller and thinner. It is advantageous to form a film by CVD that enables coating of a thin film.
A polyparaxylylene film is effective as the CVD film.

  The polyparaxylylene film 1 is a film formed by polymerizing paraxylylene or a paraxylylene derivative containing fluorine, and is excellent in corrosion resistance, heat resistance, and non-gas permeability.

  In the present invention, the polyparaxylylene film is not particularly limited as long as it is composed of paraxylylene containing fluorine, and typical ones are shown below.

  Of those represented by Chemical Formula 1 to Chemical Formula 5, polytetrafluoroparaxylylene represented by Chemical Formula 1, which has high heat resistance, is particularly preferably used. The polyparaxylylene film is formed by a vapor deposition polymerization method that falls under the category of CVD (Chemical Vapor Deposition).

  As an example, a solid dimer such as diparaxylylene is used as a raw material, the first step in which vaporization of this diparaxylylene occurs, the second step in which diradical paraxylylene is generated by thermal decomposition of the dimer, and the film formation Adsorption and polymerization of the diradical paraxylylene on the surface are simultaneously performed, and it is formed by three steps, the third step in which a high molecular weight polyparaxylylene film is formed.

In the present embodiment, the thickness of the polyparaxylylene film is not particularly limited, but the thickness is preferably 1 μm to 30 μm, more preferably the film thickness of the polyparaxylylene film. Is 2 μm to 15 μm. In the case of 2 μm or less, for example, the terminal-attached electrochemical cell that is a film to be deposited tends to be cut at an acute angle portion at the tip of the positive electrode can edge.
On the other hand, when the thickness is 15 μm or more, the film formation time is extended, which is disadvantageous in terms of cost.

  As the material of the gasket, polypropylene or amide resin is usually used. When performing reflow soldering, it is necessary to use a heat resistant resin. In order to increase the strength of the gasket, it is also effective to add a filler such as glass fiber.

  The reflow soldering temperature to the circuit board is going higher due to the requirement of lead-free solder. The higher the reflow temperature, the higher the gasket material must withstand high temperatures. The higher the heat resistance of the gasket material, the more expensive it is. For example, polyetheretherketone (PEEK) that can withstand a 260 ° C. reflow temperature is very expensive. However, by improving the sealing property by the method of the present invention, it is possible to use a resin such as polyphenylene sulfide (PPS) which usually has only a reflow of about 240 ° C. In addition, polyamides such as nylon that could not be used for electrochemical cells using a non-aqueous solvent due to moisture permeability can be used.

  In recent years, electrochemical cells have been required to be thinner as equipment becomes thinner. Therefore, the distance B between the negative electrode terminal and the positive electrode can shown in FIG. 1 is becoming increasingly smaller. If this part was small, shorts were very likely to occur due to variations and handling of parts in the process. In addition, when a device incorporating the electrochemical cell with a terminal is used in a humid environment, condensation is likely to occur between the negative electrode terminal and the positive electrode can and a short circuit is likely to occur. If a short circuit occurs, it will not function as an electrochemical cell.

Example 1
The present Example 1 shows the Example using the secondary battery used as an example of an electrochemical cell. A secondary battery having a diameter of 6.8 mm and a height of 2.1 mm was produced. The component parts mainly include a positive electrode can, a positive electrode active material, a negative electrode can, a negative electrode active material, an electrolytic solution, a separator, and a gasket.
Furthermore, the terminal of the shape shown in FIGS. 4 and 5 was attached by laser welding.

  As shown in FIG. 6, the terminal-attached electrochemical cell thus produced was placed in the notch 114 of the silicon rubber substrate 113 and arranged, and then the polytetrafluoroparaxylylene represented by Chemical Formula 1 was formed by a CVD apparatus. Was formed to a predetermined thickness.

  As an evaluation, the capacity retention rate (%) after storage at 60 ° C., humidity 90%, 2.3 V, and storage was examined. The number of days when the capacity retention rate after storage was 50% or less was examined. The evaluation number was 10 and the average value was calculated.

The capacity of the battery thus produced was measured by charging at a constant current of 50 μA, charging for 5 hours after reaching 2.3 V, and discharging at a constant current of 50 μA and a final voltage of 0.7 V.
The results are shown in Table 1.

  As shown in Examples 1 to 4, it can be seen that the polytetrafluoroparaxylylene thickness is 2 μm or more, a good capacity retention rate is exhibited, and it is strong against humidity. As shown in Comparative Example 1, when the film thickness is thin, the capacity is rapidly deteriorated. Moreover, the variation of the maintenance rate was large. This is presumably because the polytetrafluoroparaxylylene thickness was as thin as 1 μm, which caused defects due to handling and the like, and it was easy for moisture to enter the battery.

(Example 2)
Next, an example using a coin-type electric double layer capacitor as an example of an electrochemical cell will be described. An electric double layer capacitor having a diameter of 4.8 mm and a height of 1.4 mm was produced. The component parts mainly include a positive electrode can, a conductive adhesive, a positive electrode molded body of a polarizable electrode, a negative electrode can, a conductive adhesive, a negative electrode molded body of a polarizable electrode, an electrolyte, a separator, and a gasket.
A terminal having the shape shown in FIGS. 1 and 2 was attached thereto by laser welding. The positive electrode terminal 104 and the negative electrode terminal 110 were made of stainless steel. Plating layers 107 and 109 made of solder were provided at the connection portions of the terminals with the circuit board.

  As shown in FIG. 1, the terminal-attached electric double layer capacitor thus prepared was arranged on an adhesive substrate, and then a polytetrafluoroparaxylylene represented by Chemical Formula 1 was predetermined by a CVD apparatus. The thickness was formed.

  The terminal double-layered electric double layer capacitor coated with polytetrafluoroparaxylylene was heated in the same manner as reflow soldering. As a reflow soldering condition, the maximum temperature was 260 ° C.

  As an evaluation, the capacity retention rate (%) after storage at 60 ° C., humidity 90%, 2.5 V application, and storage was examined. The number of days when the capacity retention rate after storage was 50% or less was examined. The evaluation number was 10 and the average value was calculated.

The capacity of the electric double layer capacitor thus produced was measured by charging for 2.5 V for 5 hours and discharging with a constant current of 5 μA and a final voltage of 1.5 V.
The results are shown in Table 2.

  In general, the capacity maintenance rate of an electrochemical cell that has undergone reflow deteriorates more quickly than that without reflow. It is clear when Examples 1 to 4 are compared.

  As shown in Examples 5 to 8, it can be seen that the thickness of the polytetrafluoroparaxylylene is 2 μm or more, a good capacity retention rate is exhibited, and it is strong against humidity. As shown in Comparative Example 2, when the film thickness is thin, the capacity is rapidly deteriorated. Moreover, the variation of the maintenance rate was large. This is presumably because the polytetrafluoroparaxylylene thickness was as thin as 1 μm, which caused defects due to handling and the like, and it was easy for moisture to enter the battery. The tendency was the same as in Examples 1 to 4.

DESCRIPTION OF SYMBOLS 1 Film | membrane 101 Laser welding point 102 Laser welding point 103 Positive electrode can 104 Positive electrode terminal 1041 Positive electrode terminal 1042 Positive electrode terminal 105 Negative electrode can 106 Contact surface 107 Plating layer 1071 Plating layer 1072 Plating layer 108 Gasket 109 Plating layer 1091 Plating layer 1092 Plating layer 110 Negative electrode Terminal 1101 Negative terminal 1102 Negative terminal 112 Electrochemical cell with terminal 113 Substrate 114 Cut 201 Step B B Distance between negative terminal and positive electrode can

Claims (8)

A terminal-attached electrochemical cell having terminals that can be soldered to a circuit board on the surface, and containing a positive electrode, a negative electrode, a nonaqueous solvent, an electrolyte containing a supporting salt, and a separator,
Of the total surface of the electrochemical cell with terminals, polyparaxylylene film formed by CVD other than the portion in contact with the circuit board of the terminal is formed, at the surface opposite to the circuit board of the electrochemical cell, wherein the poly An electrochemical cell with a terminal, characterized in that the surface of a positive electrode can, a gasket, and a negative electrode can are continuously covered with a paraxylylene film . A terminal-attached electrochemical cell having terminals that can be soldered to a circuit board on the surface, and containing a positive electrode, a negative electrode, a nonaqueous solvent, an electrolyte containing a supporting salt, and a separator,
Of the entire surface of the flat electrochemical cell with terminal, a polyparaxylylene film formed by CVD is formed on the surface other than the solder-plated portion of the terminal, on the surface opposite to the circuit board of the electrochemical cell. The electrochemical cell with a terminal is characterized in that the surface of the positive electrode can, the gasket and the negative electrode can are continuously covered with the polyparaxylylene film . Before electrochemical cell with terminals according to claim 1 or 2, characterized in that Kipo Riparakishiriren film is poly tetrafluoroethylene-para-xylylene. The polyparaxylylene film electrochemical cell with terminals according to any one of claims 1 3 having a thickness characterized in that it is a 2μm~15μm of.   The terminal-equipped electrochemical cell according to claim 1, wherein the terminal has a step. It is a manufacturing method of the electrochemical cell with a terminal according to claim 1 or 2,
On the sheet-like substrate having adhesiveness, the step of arranging the surface to be connected to the substrate of the electrochemical cell with terminals in contact with the substrate,
Forming a polyparaxylylene film by CVD on the electrochemical cells with terminals arranged on the substrate;
A method for producing an electrochemical cell with a terminal, comprising: It is a manufacturing method of the electrochemical cell with a terminal according to claim 1 or 2,
Inserting the solder-plated portion of the terminal of the electrochemical cell with terminal into the substrate,
Forming a polyparaxylylene film by CVD on the electrochemical cell with terminals standing on the substrate;
The manufacturing method of the electrochemical cell with a terminal characterized by having.   8. The terminal according to claim 7, wherein the base on which the electrochemical cell with terminal is set has rubber elasticity, and the base has a groove or a notch for setting up the electrochemical cell with terminal. Manufacturing method of attached electrochemical cell.

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