JPH02214129A - Sealing of electronic member - Google Patents

Abstract

PURPOSE:To obtain an excellent sealing effect and to increase an effective area of an electronic member by setting specific conditions to the following: a width of a sealing end part where protective films are melted and bonded directly; a protective film formed by laminating a thermoplastic bonding layer on a plastic film. CONSTITUTION:In order to reduce a moisture-permeating amount from a sealing end part to a minimum or to set the amount to a practically trouble-free range by increasing it by about 10%, a protective film is sealed in such a way that a width W of a sealing end part satisfies Formula I. In the Formula I, a thickness of a thermoplastic bonding layer of the protective film is designated as d1 (mm); its moisture-permeating degree is designated as t1; a width of its plastic film is designated as d2 (mm); its moisture-permeating degree is designated as t2; the width of the sealing end part is designated as W (mm); W0=(d1.d2.t1/ t2) 1/2. Thereby, an excellent sealing effect is obtained, and an effective area of the electronic member is increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention seals electronic components such as solar cells, electroluminescent lamps, and magneto-optical recording materials whose performance is significantly degraded by water vapor transmission. The present invention relates to a method for sealing electronic components, the purpose of which is to significantly improve durability.

[Prior art and its problems] Conventionally, the surface of a solar cell, an electroluminescent lamp, or a magneto-optical recording member formed on a flexible substrate is sealed using a protective film. prevents curls,
In addition, in order to prevent moisture from entering from the opposite side, it is common to attach a similar protective film to the back side as well.

Moisture-proof films such as fluororesin films and polyester films, which have low permeability to water vapor and various corrosive gases, are used as such protective films, but these moisture-proof films are difficult to heat-fuse by themselves, so they are not particularly suitable. Kaisho 53-6
As disclosed in Publication No. 9593 and Japanese Patent Application Laid-Open No. 62-51192, a protective film with an adhesive layer is formed by laminating an adhesive layer made of a thermoplastic resin, and then electronic components are sandwiched from both sides and the whole is heat-sealed. A method of sealing is used.

When sealing an electronic component using such a protective film, the protective film has a sealed end where the protective films are directly fused together around the electronic component so that the electronic component to be sealed is not exposed on the sealed end surface. Take structure. In this case, the thermoplastic resin layer of the adhesive layer, which forms part of the cross section of the sealed end, has a high moisture permeability when compared to fluororesin film or polyester film, so the width of the sealed end can be adjusted. It was made as large as possible, and the gas expansion length was made long.

However, the overlapping portion of the end faces is a so-called dead space, and the effective area of an electronic component with such a structure is narrowed, which is not a preferable form from the point of view of effective use of area.
In order to improve this problem, Japanese Patent No. 249293 proposes a method in which a protective film is folded in two. However, as described therein, conventionally the width of this sealed end was set at 2.
Accordingly, conventional sealing methods have the problem of forming a dead space of at least 2 mm or more in width around the electronic component.

[Object of the Invention] The present invention was made in view of the current situation, and provides an electronic component that has the same excellent sealing effect as the conventional method for sealing electronic components and can increase the effective area of the electronic component. The purpose of this invention is to provide a sealing method.

[Structure and operation of the invention] As a result of a detailed study of the conventional sealing method described above, the present inventor found that the permeation of gas such as water vapor causes heat in the adhesive layer that forms part of the cross section of the sealed end. We discovered that there is a region other than the plastic resin layer surface where gas permeation is dominant from the protective film surface, and for the above purpose, we conducted extensive research into a method for sealing electronic components that has a wide effective area and excellent durability. As a result, the width (W>) of the sealed end where the protective films overlap each other is
The inventors have discovered that by setting specific conditions for a protective film formed by laminating thermoplastic adhesive layers, it is possible to seal with a high sealing effect and a wide effective area, and have thus arrived at the present invention.

That is, the present invention covers an electronic component with a protective film made of a plastic film laminated with a heat-sealable thermoplastic adhesive layer so that a sealed edge is formed around the electronic component, where the protective films are directly fused together. In the heat-sealing method for electronic components, the thickness of the thermoplastic adhesive layer of the protective film is d1 (mm), and the moisture permeability is 1.
1, and the thickness of the plastic film is dz (4
m), the moisture permeability is 12, and the width of the sealed end is W(lI
This is a method for sealing an electronic component, characterized in that the electronic component is sealed so that the following formula (%) is satisfied when Im).

The present invention will be explained in detail below.

The protective film used in the present invention is a laminated film in which a heat-sealable thermoplastic adhesive layer is laminated on a plastic film. Such plastic films include:
Plastic films with low permeability to water vapor and corrosive gases and excellent transparency are used. Among them, polyester films such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polyether ether ketone, polyarylate, and tetraethylene terephthalate are used. Films of fluoroethylene, monochloride trifluoroethylene, fluoroethylene fluoride propylene copolymers, etc. are suitable.

Such plastic films are laminated with heat-sealable thermoplastic adhesive layers, coated with metal thin films, metal oxide thin films, and corona discharge treatment.

Plasma treatment, glow discharge treatment, reverse spatter treatment.

Surface treatment such as roughening treatment, known anchor coating treatment, or printing may be performed.

In addition, in this treatment, it is desirable that the total light transmittance of the plastic film treated with white light is 60% or more, more preferably 80% or more. Known additives such as ultraviolet inhibitors are preferably added within this range.

The thickness of the plastic film of the present invention is not particularly limited, but from the viewpoint of suitability as a sealing material for electronic components,
A range of 400 μm is desirable. In terms of mechanical properties and flexibility, the thickness is more preferably in the range of 30 to 200 μm.

Next, the heat-sealable thermoplastic adhesive layer as used in the present invention refers to a plastic layer that can be bonded by heating and pressure, and typical examples thereof include the following.

Examples include polyester, polyamide, ionomer, ethylene vinyl acetate copolymer, acrylic resin such as acrylic ester, methacrylic ester, polyvinyl acetal, phenol, modified epoxy resin, and copolymers and mixtures thereof. , but not necessarily limited to these.

Among these, polyester, polyamide, ionomer,
Acrylic resin and ethylene vinyl acetate copolymer are preferable. Furthermore, in areas where high durability is required for electronic components, ionomers and ethyl acrylate are used.

Particularly preferred is an ethylene vinyl acetate copolymer.

The thickness of the heat-sealable thermoplastic adhesive layer is selected depending on the application, but in terms of adhesive strength and gas barrier properties,
The range is preferably 200 μm, more preferably 10-200 μm.
150 μm, most preferably 20-100 μm.

The method of laminating the thermoplastic adhesive layer on the pretreated plastic film includes a method of dissolving the components of the thermoplastic adhesive layer in an organic solvent and coating it;
Known methods such as a method of melting the components of the thermoplastic adhesive layer and extrusion lamination, or a method of preparing a sheet of the thermoplastic adhesive layer in advance and adhesively laminating the sheets by dry lamination or the like can be employed.

The heat-sealing temperature of the thermoplastic adhesive layer can be appropriately selected depending on the characteristics of the thermoplastic adhesive layer used, but it is desirable that the thermoplastic adhesive layer can be heat-sealed at a temperature of 80 to 180°C.

Furthermore, various known processes can be employed for heat-sealing and sealing electronic components such as solar cells, electroluminescent lamps, or magneto-optical recording members with such a protective film. For example, when sealing a flexible amorphous silicon solar cell on a polymer substrate, the photoelectric conversion surface of the solar cell and the thermoplastic adhesive surface of the protective film facing the polymer substrate are stacked facing each other. The sheets are heat-pressed using a hot roll and the two are pasted together. At this time, the current extraction electrode is drawn out from the solar cell, and at the same time, the solar cell portion is placed inside the protective film with a width of W from the end surface.

As a result, the upper and lower parts of the solar cell are protected by protective films with thermoplastic adhesive layers, and the peripheral side parts are sealed with a width W where the thermoplastic adhesive layers are directly exposed to each other, allowing the solar cell to be protected from the surrounding environment. protected.

However, as a result of accelerated deterioration tests of such solar cell modules in high temperature and high humidity environments, there were no morphological changes such as curling because both sides were laminated with such protective films, but the internal solar cells did not change. Corrosion of the electrode was observed in the surrounding area. It has been found that this phenomenon depends on the width W of the sealed end of the protective film, and that there is an optimum range for W in which corrosion is suppressed.

That is, the moisture permeability t1 of the thermoplastic adhesive layer of the protective film
For such a protective film, the moisture permeability t2 is greater than the water vapor permeability t2 of plastic films such as fluororesin films and polyester films, so the aforementioned deterioration phenomenon is thought to be caused by the intrusion of water vapor from the thermoplastic adhesive layer in the cross section of the sealed end. Conventionally, it has been assumed that corrosion can be suppressed by increasing the width W of the sealing end, and based on the results of accelerated deterioration tests, as mentioned above, it is sufficient to set W at a certain value or more, specifically 2U or more. It was said that

However, the inventors of the present invention discovered that deterioration occurs when W is increased with a margin in mind, and as a result of a detailed study of this phenomenon, they surprisingly found that the sealing edge, which had been ignored in the past, It has been found that water vapor permeation through the surface of the protective film cannot be ignored.

In other words, the amount of water vapor that permeates from the side surface of the sealed end, specifically from the thermoplastic adhesive layer that forms part of it, is determined by its width W.
On the other hand, the amount of moisture permeable from the surface of the protective film at the sealed end increases in proportion to the width W. From this, it was found that there is a value Wo of the width W at which the amount of moisture permeation from the side surfaces and the surface is minimized.

This value Wo is the thickness dl of the thermoplastic adhesive layer of the protective film.
It depends on the moisture permeability, the thickness dl of the plastic film, and the moisture permeability t2, and is approximated by the following formula (%). Therefore, by using an appropriate adhesive layer and a protective film for the plastic film, the width can be increased contrary to conventional wisdom. 2mm
It was found that the sealing effect equivalent to the conventional amount can be obtained at the following sealed end portions.

As a result of various estimates, in order to keep the amount of moisture permeation from the sealed end to the minimum or a 10% increase above that which does not cause any practical problems, the width W of the protective film and the sealed end must be such that Wo>F7. hour, 2
＞W≧Wo/V2 When F7≧Wo, J 2'Wo ＞W≧Wo / J
It was found that sealing should be performed so as to satisfy 2.

At this time, the moisture permeability t2 of the protective film is t+/1
It is preferable to use a plastic with good moisture resistance that satisfies 0>t2, and furthermore, the thickness dl of the adhesive layer is 4dz>
dl >0.05d2 is preferred.

In order to further minimize the moisture permeability and increase the effective area, a fluororesin film or the like whose moisture permeability t2 normally satisfies t+/20>t2 is used as the plastic film, and the width W of the sealing end is It is preferable that the following formula is satisfied.

When Wo>J2, 2>W≧Wo/V2 When J7≧Wo, 3f Pre-Wo/4>W≧Wo/J 2-What is important in the present invention is the structure of the protective film and the sealed end. The point is to set the width so that it satisfies each of the above-mentioned conditions and seal it.

By doing so, a sufficient sealing effect can be obtained with a narrow sealing end of less than 2 mm, and the effective area can be increased.

Note that the electronic components to which the present invention can be applied are not particularly limited, but from the above points, electronic components such as solar cells, electroluminescent elements, optical recording media, etc., which have a receiving/emitting part, and in particular electronic parts having a receiving/emitting part with a wide surface. This is particularly effective for sheet-like or plate-like electronic components.

[Effects of the Invention] As described above, the method for shipping electronic components according to the present invention is based on the width (W) of the sealed end where the protective films are directly fused together, and the lamination of the thermoplastic adhesive layer on the plastic film. This was achieved by setting specific conditions for the protective film, which is made of plastic, to find a specific range with a high sealing effect.

As a result, it is possible to reduce the dead space of electronic components such as solar cells, electroluminescent lamps, and even optical recording members that have a large active area, and as a result, the effective area of these electronic components can be increased. In addition, as a result of being able to select a width W that balances the infiltration of water vapor, etc. from the sealing window part and the end face cross section,
Durability has also been improved. As described above, the present invention provides a very useful sealing method for electronic components in various fields, and especially sheet-like or plate-like electronic components using flexible substrates and the like.

The present invention will be explained below based on examples in which the present invention is applied to the sealing of solar cells and electroluminescent elements.

[Example 1] A thin indium oxide film was formed by sputtering on one side of a 200 μm thick polyethylene naphthalate film to a thickness of 100 μm as an undercoat layer for improving moisture resistance and adhesion.

A protective film was obtained by laminating a 100 μm thick ethylene-vinyl acetate copolymer resin sheet as a heat-sealable adhesive layer on the indium oxide thin film-covered surface by extrusion lamination.

The moisture permeability (gr-mm/rd-dad) of the indium oxide-coated polyethylene naphthalate film and ethylene-vinyl acetate copolymer sheet used was JIS-
When measured using a method similar to Z-0280, it was 0.03
and 6.8.

Next, using a polyethylene terephthalate film with a thickness of 100 μm as a substrate, a 10 cm×
A sheet-like amorphous silicon solar cell having an integrated structure with a size of 10 Cn square and an output of 0.6 W was obtained.

The protective film was placed on both the photoelectric conversion surface and the substrate surface of this sheet-shaped amorphous silicon solar cell so that the adhesive layer surfaces faced each other, and the film was bonded under pressure between rolls heated to 150°C.

At this time, the width W of the sealing edge where the protective films formed around the solar cells are directly adhered to each other was set to various values shown in Table 1, and the solar cell modules of the samples shown in Table 1 were obtained. Ta.

After this solar cell module was left in an atmosphere of 80° C. and 90% RH for 300 hours, the corrosion state of the electrodes of the solar cell module was observed. The results are shown in Table 1.

As shown in Table 1, the width of the sealed end falls within the range of the present invention.
, 5 to 2.0 mm, the area efficiency is large at 90% or more, and there is no deterioration of unit parts of the module, indicating that the method of the present invention is an effective sealing structure.

[Example 2] A titanium metal thin film was formed as an undercoat layer on one side of a 200 μm thick ethylene monochloride trifluoride film to a thickness of 30 μm by sputtering. A protective film was obtained by laminating a 50 μm thick ethylene-ethyl acrylate copolymer resin sheet as an adhesive layer on the coated surface of the titanium metal thin film by dry lamination. In addition, the moisture permeability of titanium film-attached chloride-pressure fluorinated ethylene film and ethylene-ethyl acrylate copolymer sheet (
car-mm/rrt-day) were measured in the same manner as in Example 1, and were 0.02 and 6.8, respectively.

Next, a dielectric layer consisting of cyanoethyl cellulose resin and barium titanate powder was placed on 1 mm M metal foil for 20 minutes.
It was formed by screen printing to a thickness of μm.

On the other hand, a light-emitting layer made of cyanoethyl cellulose resin and Zn5()In> powder was formed on an electrode film of 600 ITO (indium tin oxide) transparent electrode films formed by sputtering on a polyethylene terephthalate film with a thickness of 100 μm. It was formed to a thickness of 40 μm using a screen printing method. Then, both of them were pasted together between heated rolls to obtain an electroluminescent element with a size of 3 x 5 cm square.

The protective film was stacked on both sides of this electroluminescent device so that the adhesive layer surfaces faced each other, and the film was bonded under pressure through rolls heated to 150°C. At this time, sealed end portions in which protective films were directly adhered to each other around the electroluminescent element were provided in various widths W shown in Table 2, and the electroluminescent modules of the samples shown in Table 2 were obtained.

This EL element was left in an 80'CX 90% RH (7) atmosphere for 1300 hours, and an accelerated deterioration test was performed.
I got the result.

Table 2 Table 2 shows sample No. where the sealing width W at the sealing end is narrow.

In case 6, the moisture permeability from the ethylene-ethyl acrylate resin, which is the thermoplastic adhesive layer that forms the side surface of the sealed end, was large, and the electrical bonding surface between the electric ring light emitting element and the external electrode was destroyed. Conceivable.

On the other hand, in the case of sample No. 10 with a wide sealing width W, water vapor permeation was dominant from the protective film portion of the end surface width rather than the cross-sectional surface, and it is considered that this corroded the electrode portion of the module end surface.

On the other hand, it can be seen that the sealing end portion having a width in the range of 1.3 to 2.0 mm according to the present invention exhibits an excellent sealing effect and has an improved area efficiency of 80% or more.

Claims (1)

[Claims] 1. A protective film made of a plastic film laminated with a thermoplastic adhesive layer that can be heat-sealed is used to form a sealed end portion around the electronic component where the protective films are directly fused together. In a method for sealing an electronic component by coating and heat-sealing the protective film, the thickness of the thermoplastic adhesive layer of the protective film is d_1 (mm), the moisture permeability is t_1, and the thickness of the plastic film is d_2 (mm). , When the moisture permeability is t_2 and the width of the sealing end is W (mm), when W_0>√2, 2>W≧W_0/√2 When √2≧W_0, √2W_0>W≧ W_0/√2 [However, in the previous equation, W_0=(d_1・d_2・t_1/
t_2)_1_/_2] A method for sealing an electronic component, characterized in that the electronic component is sealed so as to satisfy the following.