JP2018019054A - Sealing film and sealing film-coated electronic component mounting substrate - Google Patents

Abstract

[Problem] To provide a sealing film capable of sealing the unevenness of an electronic component mounting substrate with excellent conformability, and a sealing film-covered electronic component mounting substrate equipped with such a sealing film. [Solution] The sealing film 100 of the present invention is used to cover the substrate 5 of an electronic component mounting substrate 45 and the electronic components 4 mounted on the substrate 5, is made mainly of a resin material, and has an elongation rate at the softening point determined in accordance with JIS K 6251 of 150% or more and 3500% or less. [Selected Figure] Figure 3

Description

  The present invention relates to a sealing film and a sealing film-covered electronic component mounting substrate.

  Conventionally, in electronic devices such as mobile phones, smartphones, calculators, electronic newspapers, tablet terminals, videophones, personal computers, for example, electronic component mounting substrates on which electronic components such as semiconductor elements, capacitors, and coils are mounted. Although mounted, the electronic component mounting board may be sealed with resin for the purpose of preventing contact with external factors such as moisture and dust.

  Sealing with such a resin includes, for example, a potting method in which a thermosetting resin such as a highly fluid urethane resin is injected and sealed after an electronic component mounting substrate is placed in a metal cavity. A coating method is known in which a plastic resin is applied to an electronic component mounting substrate in a molten state and then solidified to be coated (sealed).

  However, the potting method has a problem in that it takes time to cure the thermosetting resin, and further, usually requires a metal cavity for sealing, resulting in an increase in the weight of the resulting electronic device. In addition, the coating method has a problem that it takes time and labor to manage the viscosity of the thermoplastic resin in a molten state and to separate the coating on the thermoplastic resin application region.

  In order to solve such problems, it has been proposed to apply a barrier film having hot melt properties to an electronic component mounting substrate (see, for example, Patent Document 1).

  However, in this case, the followability to the unevenness formed due to the electronic component mounting substrate including the electronic component is not sufficiently obtained, and as a result, the barrier property against external factors such as moisture and dust is sufficiently improved. It has not reached.

JP 2009-99417 A

  An object of the present invention is to provide a sealing film that can be sealed with excellent followability with respect to the unevenness provided on the electronic component mounting substrate, and a sealing film-covered electronic component mounted with the sealing film. It is to provide a substrate.

Such an object is achieved by the present invention described in the following (1) to (7).
(1) A sealing film used for covering a substrate provided on an electronic component mounting substrate and an electronic component mounted on the substrate,
A sealing film comprising a resin material as a main material and having an elongation at a softening point of 150% or more and 3500% or less determined in accordance with JIS K 6251.

  (2) The said film for sealing is a film for sealing as described in said (1) whose linear expansion coefficient in a temperature range of 25 degreeC or more and 80 degrees C or less is 100 ppm / degrees C or less.

  (3) The said film for sealing is a film for sealing as described in said (1) or (2) which has one or more layers which use a thermoplastic resin as the main material.

  (4) The sealing film according to any one of (1) to (3), wherein the sealing film has an average thickness of 10 μm or more and 200 μm or less.

(5) The said film for sealing is a film for sealing in any one of said (1) thru | or (4) whose storage elastic modulus in 80 degreeC is 1 * 10 < ⁵ > Pa or more.

  (6) The sealing film according to any one of (1) to (5), wherein the substrate is a printed wiring board.

  (7) The sealing film according to any one of (1) to (6) above, and the electronic component mounting substrate including the substrate and the electronic component covered with the sealing film. A film-covered electronic component mounting substrate for sealing.

  According to the present invention, the sealing film is composed mainly of a resin material, and the elongation rate of the sealing film at the softening point required in accordance with JIS K 6251 is 150% or more and 3500% or less. . Therefore, by placing a sealing film so as to cover the substrate and the electronic component, and then heating and softening the sealing film and reducing the pressure, then cooling and pressurizing the sealing film. The substrate and the electronic component can be covered in a state where the unevenness formed by mounting the electronic component on the substrate is sealed with excellent followability. Therefore, in the sealing film-covered electronic component mounting substrate obtained by coating this sealing film, it is possible to accurately suppress or prevent the electronic component from coming into contact with external factors such as moisture and dust. .

It is a longitudinal cross-sectional view which shows 1st Embodiment of the film for sealing of this invention. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the film for sealing of this invention. It is a longitudinal cross-sectional view for demonstrating the sealing method of the electronic component mounting board | substrate using the film for sealing of this invention.

  Hereinafter, the sealing film and the film-coated electronic component mounting substrate of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

  The sealing film of the present invention is a sealing film used for covering a substrate provided on an electronic component mounting substrate and an electronic component mounted on the substrate, and is composed mainly of a resin material. The elongation at the softening point obtained in accordance with JIS K 6251 is 150% or more and 3500% or less.

  Further, by using the above-described sealing film, the step of arranging the sealing film so as to cover the substrate and the electronic component with the covering of the electronic component mounting substrate and the electronic component, and the sealing Heating and depressurizing step for heating and softening the film for cooling and cooling and pressurizing step for cooling the sealing film and covering the substrate and the electronic component with the sealing film by pressurizing It is implemented by going through.

  Using such a sealing film, when applied to an uneven coating formed by mounting an electronic component on a substrate, the sealing film in a softened state is formed in the cooling / pressurizing step. Since it is cooled in a pressurized state, the substrate and the electronic component can be coated in a sealed state with excellent followability. Therefore, in the sealing film-covered electronic component mounting substrate obtained by coating the sealing film, it is possible to accurately suppress or prevent the electronic component from coming into contact with external factors such as moisture and dust. Therefore, it is possible to improve the reliability of the obtained electronic device equipped with the sealing film-covered electronic component mounting substrate and thus the sealing film-covered electronic component mounting substrate.

  In the following description of the sealing film and the sealing film-covered electronic component mounting substrate of the present invention, the electronic component mounting substrate 45 in which the electronic component 4 is mounted (mounted) on the substrate 5 such as a printed wiring board. In FIG. 5, the mounting of the electronic component 4 on the substrate 5 forms the irregularities 6 including the convex portions 61 and the concave portions 62 on the substrate 5. And the case where this unevenness | corrugation 6 is coat | covered using the film 100 for sealing of this invention is demonstrated. Examples of the substrate 5 include a printed wiring board, and examples of the electronic component 4 mounted on the substrate 5 include a semiconductor element, a capacitor, a coil, a connector, and a resistor.

<Sealing film>
First, the sealing film 100 of the present invention will be described.

  FIG. 1 is a longitudinal sectional view showing a first embodiment of the sealing film of the present invention, and FIG. 2 is a longitudinal sectional view showing a second embodiment of the sealing film of the present invention. In the following description, for convenience of description, the upper side in FIGS. 1 and 2 is referred to as “upper” and the lower side is referred to as “lower”.

  The sealing film 100 of the present invention is composed of a resin material as a main material, and has an elongation at a softening point required in accordance with JIS K 6251 of 150% or more and 3500% or less.

  Such a sealing film 100 may be composed of any resin material as long as the elongation is within the above range. Examples of the resin material include low-density polyethylene, Density polyethylene, ethylene copolymer, polyolefin resin such as stretched polypropylene and unstretched polypropylene, ionomer resin, polyester resin such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate resin, polystyrene resin, acrylic resin, nylon-6 Nylon-6, nylon-6,10, nylon-6T composed of hexamethylenediamine and terephthalic acid, nylon-6I composed of hexamethylenediamine and isophthalic acid, nylon-9T composed of nonanediamine and terephthalic acid, Mechi Polyamide-based resins such as nylon-M5T composed of pentadiamine and terephthalic acid, nylon-6,12 composed of caprolactam and lauryllactam, nylon-6-6,6 composed of hexamethylenediamine, adipic acid and caprolactam, Examples thereof include thermoplastic resins such as polyvinyl chloride and polyvinyl alcohol, and a single layer body including at least one of them or a multilayer body may be used.

  The resin material included in the sealing film 100 may be a thermosetting resin such as an epoxy resin, a phenol resin, a melamine resin, or a silicone resin, an acrylic resin, or a urethane resin in addition to the thermoplastic resin material described above. A UV curable resin may be included.

  Among these, the sealing film 100 is preferably a single-layer body containing a polyolefin resin as a main material or a multilayer body having one or more layers containing a polyolefin resin as a main material. It is more preferable that the multilayer body has one or more layers containing a main resin as a main material. Thereby, the elongation at the softening point of the sealing film 100 can be easily set to 150% or more and 3500% or less.

  Hereinafter, an example of the sealing film 100 composed of a multilayer body having one or more layers containing a polyolefin-based resin as a main material will be described. In addition, although this embodiment demonstrates the multilayer body which consists of 4 layers, it is not limited to the multilayer body which consists of 4 layers especially.

<< First Embodiment >>
As shown in FIG. 1, in this embodiment, the sealing film 100 includes an outermost layer 11, an intermediate layer 12, an intermediate layer 13, and an innermost layer 14, which are shown in FIG. It is comprised with the laminated body laminated | stacked in this order from the other side of the mounting substrate 45. FIG.

  The outermost layer 11 is for imparting an oxygen gas barrier property to the sealing film 100 and is a layer containing an oxygen gas barrier resin.

  As this oxygen gas barrier resin, in this embodiment, the ethylene content to be copolymerized is 27 to 44 mol in an ethylene-vinyl alcohol copolymer saponified product (hereinafter sometimes abbreviated as “EVOH”). % Is preferable.

  Further, the average thickness of the outermost layer 11 is preferably 1 μm or more and 30 μm or less, and more preferably 5 μm or more and 15 μm or less. By setting the average thickness of the outermost layer 11 within such a range, the sealing film 100 can be reliably imparted with an oxygen gas barrier property, and the elongation at the softening point of the sealing film 100 is 150% or more and 3500. % Can be reliably set within the range of% or less.

  In addition, when it is not necessary to give oxygen gas barrier property to the film 100 for sealing, you may abbreviate | omit formation of the outermost layer 11 in the film 100 for sealing.

  The intermediate layer 12 has an elongation rate at the softening point of the sealing film 100 set to 150% or more and 3500% or less, and is excellent in adhesion to the unevenness 6 and shape followability. It is a layer containing an ionomer resin as a main material for the purpose of making the stopping film 100 excellent in toughness.

  Here, in this specification, the ionomer resin is a binary copolymer having ethylene and (meth) acrylic acid as a constituent component of the polymer, ethylene, (meth) acrylic acid, and (meth) acrylic acid ester. Is a resin crosslinked with metal ions, and one or two of them can be used in combination.

Examples of the metal ion include potassium ion (K ⁺ ), sodium ion (Na ⁺ ), lithium ion (Li ⁺ ), magnesium ion (Mg ⁺⁺ ), and zinc ion (Zn ⁺⁺ ). Among these, sodium ions (Na ⁺ ) or zinc ions (Zn ⁺⁺ ) are preferable. Thereby, since the crosslinked structure in the ionomer resin is stabilized, the function as the intermediate layer 12 described above can be exhibited more remarkably.

  Further, a binary copolymer having ethylene and (meth) acrylic acid as constituent components of the polymer, or a ternary copolymer having ethylene, (meth) acrylic acid and (meth) acrylic acid ester as constituent components of the polymer. The degree of neutralization by the cation (metal ion) in the carboxyl group of the polymer is preferably 40 mol% or more and 75 mol% or less.

  Moreover, as for the intermediate | middle layer 12, it is more preferable that melting | fusing point (based on JIS K-7121, measured by DSC method) is 100 degrees C or less, and tensile fracture stress (measured based on JIS K-7162) is 40 MPa or less. Thereby, in the sealing method of the electronic component mounting substrate mentioned later, the board | substrate 5 and the electronic component 4 using the film 100 for sealing can be implemented easily.

  The average thickness of the intermediate layer 12 is preferably 1 μm or more and 30 μm or less, and more preferably 5 μm or more and 15 μm or less. By setting the average thickness of the intermediate layer 12 within such a range, the sealing film 100 is excellent in toughness, and the elongation at the softening point of the sealing film 100 is in the range of 150% to 3500%. It can be assumed that it is securely set within.

  In the present embodiment, the intermediate layer 13 is an ethylene-vinyl acetate copolymer as an ethylene copolymer for the purpose of setting the elongation at the softening point of the sealing film 100 to 150% or more and 3500% or less. It is a layer containing a polymer as a main material.

  Moreover, as this ethylene-vinyl acetate copolymer, the VA content to be copolymerized is preferably 5% by weight to 30% by weight, and more preferably 10% by weight to 20% by weight. If it is less than the lower limit, it may be difficult to set the elongation at the softening point of the sealing film 100 within the above range. On the other hand, when the upper limit is exceeded, the crystal part of the resin constituting the intermediate layer 13 decreases and the non-crystal part tends to increase, so that the sealing film 100 is changed to the innermost layer. Even if it is set as the structure provided with 14, there exists a possibility that additives, such as antioxidant remaining in the intermediate | middle layer 13, may elute. Therefore, it passes through the innermost layer 14 and moves to the electronic component mounting substrate 45 side. As a result, there is a possibility that the characteristics of the electronic component 4 may be inconvenient. Moreover, since the melting point tends to decrease, the heat resistance of the sealing film 100 may also decrease.

  The average thickness of the intermediate layer 13 is preferably 5 μm or more and 130 μm or less, and more preferably 20 μm or more and 80 μm or less. By setting the average thickness of the intermediate layer 13 within such a range, the elongation at the softening point of the sealing film 100 can be reliably set within the range of 150% to 3500%.

  The intermediate layer 12 and the intermediate layer 13 may be laminated in this order from the outermost layer 11 side, or the intermediate layer 13 and the intermediate layer 12 may be laminated in this order from the outermost layer 11 side. .

  The innermost layer 14 is intended to function as a blocking layer that suppresses or prevents the transition to the electronic component mounting substrate 45 side due to the elution of additives such as an antioxidant contained in the intermediate layer 13. And a layer containing an ethylene heat sealable resin as a main material.

  The innermost layer 14 is a layer that is in close contact (contact) with the electronic component 4 when the electronic component mounting substrate 45 is covered with the sealing film 100. Further, the sealing film 100 is heat sealed to the substrate 5. It functions as a layer for making it happen.

  As the ethylene-based heat-sealable resin contained in the innermost layer 14, in this embodiment, the density measured by the method defined in JIS K7112 is in the range of 0.890 to 0.910, and in JIS K7206 A linear low-density polyethylene resin (LLDPE) having a Vicat softening point of 90 ° C. or less measured by a method to be defined is preferably used.

  Further, the innermost layer 14 may contain a lubricant in addition to the ethylene heat sealable resin. In that case, as the lubricant, organic lubricants such as behenic acid amide, oleic acid amide and erucic acid amide, and inorganic lubricants such as silica, zeolite and calcium carbonate are preferably used, and one or more of these are used. Can be used in combination. The addition amount is preferably 0.1 to 5% by weight, and is usually added in the form of a masterbatch.

  The average thickness of the innermost layer 14 is preferably 1 μm or more and 20 μm or less, and more preferably 5 μm or more and 15 μm or less. By setting the average thickness of the innermost layer 14 within this range, the innermost layer 14 can be reliably provided with the function as the blocking layer, and the elongation at the softening point of the sealing film 100 is 150%. It can be reliably set within the range of 3500% or less.

  The additive such as an antioxidant is eluted from the intermediate layer 13 mainly when the sealing film 100 is heated by driving the electronic component 4 or the like. With the configuration including the innermost layer 14, the heat resistance of the sealing film-covered electronic component mounting substrate 50 that is configured by covering the electronic component mounting substrate 45 with the sealing film 100 shown in FIG. 3 can be improved. Can be planned.

  Further, in the intermediate layer 13 provided in the sealing film 100, elution of additives such as antioxidants is suppressed or prevented, and when the sealing performance by the intermediate layer 13 is ensured, The formation of the innermost layer 14 may be omitted.

  Further, in the sealing film 100, adhesion is imparted between the outermost layer 11 and the intermediate layer 12, between the intermediate layer 12 and the intermediate layer 13, and between the intermediate layer 13 and the innermost layer 14. Alternatively, an adhesive layer may be provided as necessary to enhance the adhesiveness. In particular, the adhesive resin layer is disposed between the outermost layer 11 and the intermediate layer 12 or between the intermediate layer 12 and the intermediate layer 13 because the adhesive strength is weak even in the film forming process by coextrusion. It is preferable to do.

  Examples of the adhesive resin contained in the adhesive layer include EVA, ethylene-maleic anhydride copolymer, EAA, EEA, ethylene-methacrylate-glycidyl acrylate terpolymer, or various polyolefins such as acrylic acid, methacrylic acid. Monobasic unsaturated fatty acids such as acids, dibasic unsaturated fatty acids such as maleic acid, fumaric acid, itaconic acid or the like grafted with these anhydrides, such as maleic acid grafted EVA, maleic acid grafted ethylene Known α-olefin copolymers, styrene-based elastomers, acrylic resins, epoxy resins, polyurethane resins, and the like can be used as appropriate.

  In addition, when it is set as the structure which inserts an adhesive layer between the outermost layer 11 and the intermediate | middle layer 12, or between the intermediate | middle layer 12 and the intermediate | middle layer 13, the laminated body of an adhesive layer and the intermediate | middle layer 12 is these adhesive layers. And the intermediate layer 12 may be repeated, and the laminate of the adhesive layer and the intermediate layer 13 may be a repeated body in which the adhesive layer and the intermediate layer 13 are repeatedly stacked. May be.

  In the present embodiment, the outermost layer 11, the intermediate layer 13, and the innermost layer 14 constitute a layer containing a polyolefin resin as a main material.

<< Second Embodiment >>
In addition to the case where the sealing film 100 is formed of a multilayer body having one or more layers containing a polyolefin-based resin as a main material as in the first embodiment, for example, the sealing film 100 Can be constituted by a multilayer body having one or more layers containing a polyamide-based resin as a main material. Examples of such a case include the following.

  As shown in FIG. 2, in this embodiment, the sealing film 100 includes an outermost layer 21, an intermediate layer 22, an intermediate layer 23, and an innermost layer 24, which are opposite to the electronic component mounting substrate 45 to be covered. It is comprised from the laminated body laminated | stacked in this order from the side.

  The outermost layer 21 is for imparting heat resistance to the outside of the sealing film-covered electronic component mounting substrate 50 in which the electronic component mounting substrate 45 is coated with the sealing film 100. It is a layer containing at least one kind of linear low density polyethylene.

  As the soft vinyl chloride resin, a vinyl chloride homopolymer having an average degree of polymerization of 700 to 1800, an ethylene-vinyl chloride copolymer having an ethylene content of 10% or less, or an ethylene-vinyl acetate copolymer content of 12% or less. An ethylene-vinyl acetate-vinyl chloride graft copolymer can be used, and further, a mixture obtained by adding 100% by weight of the mixture as a base resin and adding 40% to 70% by weight of a plasticizer can also be used.

  As the plasticizer, known ones such as phthalic acid, phosphoric acid, aliphatic, polyester, trimellitic acid, and pyromellitic acid can be used.

  In addition, the outermost layer 21 may contain a stabilizer, a lubricant, a processing aid, a secondary plasticizer / stabilizer, and the like.

The linear low-density polyethylene is not particularly limited, and for example, a copolymer obtained by copolymerizing hexene or octene with ethylene has a density of 0.935 g / cm ² or less, a melting point of 120 ° C. or more, and a softening point of 110 ° C. or more. Those are preferably used.

  By making the outermost layer 21 to have such a configuration, the sealing film 100 can have excellent heat resistance, and the elongation at the softening point of the sealing film 100 is 150% or more and 3500% or less. Can be set.

  Moreover, the average thickness of the outermost layer 21 is preferably 5 μm or more and 60 μm or less, and more preferably 10 μm or more and 40 μm or less. By setting the average thickness of the outermost layer 21 within such a range, heat resistance can be reliably imparted to the sealing film 100, and the elongation at the softening point of the sealing film 100 is 150% or more and 3500%. It can be reliably set within the following range.

  When the sealing film 100 is not required to consider the heat resistance of the sealing film-covered electronic component mounting substrate 50, the formation of the outermost layer 21 in the sealing film 100 is omitted. May be.

  The intermediate layer 22 is a layer containing a polyamide-based resin as a main material for the purpose of setting the elongation at the softening point of the sealing film 100 to 150% or more and 3500% or less.

  In addition, as the polyamide-based resin, for example, nylon-6,12 composed of caprolactam and lauryllactam, or nylon-6-6,6 composed of hexamethylenediamine, adipic acid and caprolactam, the ratio of 6-nylon Is preferably a copolymer nylon such as those having a ratio of 30% to 90%. By using such copolymer nylon, the elongation at the softening point of the sealing film 100 can be reliably set within the above range.

  Further, it is more preferable that the ratio of 6-nylon in the copolymer nylon is 50% or more and 85% or less, the melting point is 200 ° C. or less, and the weight average molecular weight is 20,000 or more. Thereby, since the fall of the moderate melt viscosity of the intermediate | middle layer 22 is aimed at, while being able to set the elongation rate in the softening point of the film 100 for sealing more reliably within the said range, at the time of manufacture of the film 100 for sealing The film formability of the intermediate layer 22 can be maintained.

  The average thickness of the intermediate layer 22 is preferably 1 μm or more and 40 μm or less, and more preferably 5 μm or more and 20 μm or less. By setting the average thickness of the intermediate layer 22 within such a range, the elongation at the softening point of the sealing film 100 can be reliably set within the range of 150% to 3500%.

  The intermediate layer 23 is for imparting oxygen gas barrier properties to the sealing film 100 and is a layer containing an oxygen gas barrier resin.

  As the oxygen gas barrier resin, the ethylene content to be copolymerized in the saponified ethylene-vinyl alcohol copolymer is 27 to 44 mol%, as in the outermost layer 11 of the first embodiment. It is preferable that.

  The average thickness of the intermediate layer 23 is preferably 1 μm or more and 30 μm or less, and more preferably 5 μm or more and 15 μm or less. By setting the average thickness of the intermediate layer 23 within this range, the sealing film 100 can be reliably imparted with an oxygen gas barrier property, and the elongation at the softening point of the sealing film 100 is 150% or more and 3500. % Can be reliably set within the range of% or less.

  The intermediate layer 22 and the intermediate layer 23 may be laminated in this order from the outermost layer 21 side, or the intermediate layer 23 and the intermediate layer 22 may be laminated in this order from the outermost layer 21 side. .

  Further, when it is not necessary to provide the sealing film 100 with an oxygen gas barrier property, the formation of the intermediate layer 23 in the sealing film 100 may be omitted.

  The innermost layer 24 is a layer that is in close contact (contact) with the electronic component 4 when the electronic component mounting substrate 45 is covered with the sealing film 100, and further for heat-sealing the sealing film 100 to the substrate 5. For the purpose of functioning as a layer, it is a layer containing an ethylene-based heat sealable resin as a main material.

  As the ethylene-based heat-sealable resin contained in the innermost layer 24, the same materials as those mentioned for the innermost layer 14 of the first embodiment can be used.

  The average thickness of the innermost layer 24 is preferably 1 μm or more and 20 μm or less, and more preferably 5 μm or more and 15 μm or less. By setting the average thickness of the innermost layer 24 within such a range, the elongation at the softening point of the sealing film 100 can be reliably set within the range of 150% to 3500%.

  The additive such as an antioxidant is eluted from the intermediate layer 23 mainly when the sealing film 100 is heated by driving the electronic component 4 or the like. With the configuration including the innermost layer 24, the heat resistance of the sealing film-covered electronic component mounting substrate 50 having a configuration in which the electronic component mounting substrate 45 is covered with the sealing film 100 can be improved.

  In addition, in the sealing film 100, when the sealing performance with respect to the board | substrate 5 can be ensured by the intermediate | middle layer 23, formation of the innermost layer 24 in the sealing film 100 may be abbreviate | omitted.

  Further, in the sealing film 100, as in the first embodiment, between the outermost layer 21 and the intermediate layer 22, between the intermediate layer 22 and the intermediate layer 23, and between the intermediate layer 23 and the innermost layer 24. In order to give adhesiveness or to improve adhesiveness, an adhesive layer may be provided as necessary.

  In addition, when it is set as the structure which inserts an adhesive layer between the outermost layer 21 and the intermediate | middle layer 22, or between the intermediate | middle layer 22 and the intermediate | middle layer 23, the laminated body of an adhesive layer and the intermediate | middle layer 22 is these adhesive layers. The intermediate layer 22 may be a repeated body in which the adhesive layer and the intermediate layer 23 are repeatedly stacked. The stacked body of the adhesive layer and the intermediate layer 23 may be a repeated body in which the adhesive layer and the intermediate layer 23 are repeatedly stacked. May be.

  In the present embodiment, the intermediate layer 22 constitutes a layer containing a polyamide resin as a main material.

  Further, the production method for producing the sealing film 100 of the first embodiment and the second embodiment is not particularly limited, and for example, a known coextrusion method, a dry laminating method, etc. are used for film formation and It can be obtained by laminating.

  Here, by forming the sealing film 100 with the multilayer body shown in the first and second embodiments, the elongation at the softening point of the sealing film 100 is 150% or more relatively easily. Although it can be set to 3500% or less, this elongation may be 150% or more and 3500% or less, but is preferably 150% or more and 3000% or less, and is preferably 500% or more and 2000% or less. More preferred. As a result, when the sealing film 100 is used to coat the unevenness 6 included in the electronic component mounting substrate 45, it can be covered in a state of being sealed with excellent followability to the shape of the unevenness 6. It is possible to accurately suppress or prevent the sealing film 100 from being broken in the middle.

  Further, by setting the elongation at the softening point of the sealing film 100 within the above range, even if the step in the unevenness 6 provided on the substrate 5 is as large as 10 mm or more, the sealing is performed. The film 100 can be made to follow the shape of the irregularities 6.

  The elongation at break (elongation at the softening point) can be measured according to the method described in JIS K 6251 using an autograph device (for example, AUTOGRAPH AGS-X manufactured by Shimadzu Corporation). it can.

  The softening point of the sealing film 100 is determined using a dynamic viscoelasticity measuring apparatus (for example, EXSTAR6000, manufactured by Seiko Instruments Inc.) with a distance between chucks of 20 mm, a heating rate of 5 ° C., and an angular frequency of 10 Hz. It can be measured under conditions.

  Furthermore, the linear expansion coefficient in the temperature range of 25 ° C. or more and 80 ° C. or less of the sealing film 100 is preferably 100 ppm / K or less, and more preferably 5 ppm / K or more and 50 ppm / K or less. When the linear expansion coefficient in the temperature range of 25 ° C. or higher and 80 ° C. or lower of the sealing film 100 is a value in such a range, the sealing film 100 is excellent when the sealing film 100 is heated. Since it has a stretching property, the shape followability with respect to the unevenness 6 of the sealing film 100 can be improved more reliably. Furthermore, since excellent adhesion can be maintained between the sealing film 100 and the substrate 5 and further the electronic component 4, the sealing caused by the heat generated by repeatedly driving the electronic component mounting substrate 45 is achieved. The peeling from the electronic component mounting substrate 45 of the stop film 100 can be suppressed or prevented more accurately. The linear expansion coefficient of the sealing film 100 can be calculated using, for example, a dynamic viscoelasticity measuring apparatus (for example, EXSTAR6000 manufactured by Seiko Instruments Inc.).

Further, the storage elastic modulus at 80 ° C. of the sealing film 100 is preferably 1 × 10 ⁵ Pa or more, and more preferably 2 × 10 ⁵ Pa or more and 9 × 10 ⁸ Pa or less. Thereby, when the uneven | corrugated 6 with which the electronic component mounting board | substrate 45 is equipped is coat | covered using the film 100 for sealing, the film 100 for sealing can be made to follow more reliably corresponding to the shape of the unevenness | corrugation 6. FIG. Therefore, since the sealing film 100 can be coated with better adhesion (air tightness) to the unevenness 6, the sealing film 100 covers the barrier property against external factors such as moisture and dust. It can improve more reliably. The storage elastic modulus at 80 ° C. of the sealing film 100 is determined by using a dynamic viscoelasticity measuring device (for example, EXSTAR6000, manufactured by Seiko Instruments Inc.), a distance between chucks of 20 mm, and a heating rate of 5 ° C./min. And it can be measured under the condition of an angular frequency of 10 Hz.

  The average thickness of the sealing film 100 as a whole is preferably 10 μm or more and 200 μm or less, and more preferably 20 μm or more and 150 μm or less. By setting the average thickness of the sealing film 100 within this range, the sealing film 100 can be accurately suppressed or prevented from breaking in the middle of the sealing film 100, and for sealing. The elongation at the softening point of the film 100 can be reliably set within a range of 150% to 3500%.

<Method of sealing electronic component mounting substrate>
Next, a method for sealing an electronic component mounting substrate using the above-described sealing film of the present invention will be described.

  The electronic component mounting substrate sealing method of the present embodiment includes an arranging step of arranging the sealing film 100 so as to cover the substrate 5 and the electronic component 4, heating and softening the sealing film 100, and reducing the pressure. Heating / depressurization step, and cooling / pressurization step of covering the substrate 5 and the electronic component 4 with the sealing film 100 by cooling and pressurizing the sealing film 100.

  FIG. 3 is a longitudinal sectional view for explaining a method of sealing an electronic component mounting board using the sealing film of the present invention.

Hereafter, each process of the sealing method of an electronic component mounting substrate is demonstrated sequentially.
(Arrangement process)
First, as illustrated in FIG. 3A, the sealing film 100 is disposed on the electronic component mounting substrate 45 so as to cover the substrate 5 and the electronic component 4 included in the electronic component mounting substrate 45.

(Heating and decompression process)
Next, as shown in FIG. 3B, the sealing film 100 is heated and softened, and the pressure is reduced.

  Thus, by heating the sealing film 100, the sealing film 100 is softened. As a result, with respect to the shape of the unevenness 6 formed by mounting the electronic component 4 on the substrate 5, It will be in a state where it can follow.

  At this time, the electronic component mounting substrate 45 and the sealing film 100 are arranged in a reduced-pressure atmosphere, so that not only the upper side of the sealing film 100 but also the electronic component mounting substrate 45 and the sealing film 100 The gas (air) in between is degassed.

  Thereby, it will be in the state which followed the shape of the unevenness | corrugation 6 a little while extending the film 100 for sealing.

  By this step, the sealing film 100 can be made to follow the shape of the unevenness 6 formed on the electronic component mounting substrate 45.

  The heating of the sealing film 100 and the reduced pressure of the atmosphere may be reduced after the heating or may be heated after the reduced pressure, but the heating and the reduced pressure are preferably performed almost simultaneously. Thereby, the softened film 100 for sealing can be made into the state which followed the shape of the unevenness | corrugation 6 a little reliably.

(Cooling / pressurization process)
Next, as shown in FIG. 3C, the sealing film 100 is cooled and pressurized.

  Thus, by pressurizing from the decompressed atmosphere, in the heating and decompression step, the space between the electronic component mounting substrate 45 and the sealing film 100 is degassed, and the decompressed state is maintained. As a result, the sealing film 100 is further extended, and as a result, the substrate 5 and the electronic component are softened by the softened sealing film 100 in a state where the shape of the unevenness 6 is followed with an excellent degree of adhesion (air density). 4 are coated.

  At this time, in the present invention, the elongation at the softening point of the sealing film 100 is 150% or more and 3500% or less. Therefore, since the sealing film 100 can be extended with better shape followability with respect to the unevenness 6 formed on the electronic component mounting substrate 45 during this pressurization, the sealing film in a softened state By 100, the board | substrate 5 and the electronic component 4 can be coat | covered with the outstanding adhesiveness.

  And in the state which coat | covered the board | substrate 5 and the electronic component 4 with the outstanding adhesiveness (airtightness) with the film | membrane 100 for sealing, by cooling the film | membrane 100 for sealing, this state is maintained, The sealing film 100 is solidified.

  Accordingly, the sealing film-covered electronic component mounting substrate 50 in which the substrate 5 and the electronic component 4 are covered with the sealing film 100 in a state of following the shape of the unevenness 6 formed on the electronic component mounting substrate 45. Will be obtained. Therefore, in the sealing film-covered electronic component mounting substrate 50, it is possible to accurately suppress or prevent the electronic component 4 from coming into contact with external factors such as moisture and dust. Accordingly, the reliability of the obtained electronic device including the sealing film-covered electronic component mounting substrate 50 and thus the sealing film-covered electronic component mounting substrate 50 can be improved.

  By this step, the sealing film 100 can be coated with excellent adhesion corresponding to the shape of the unevenness 6 formed on the electronic component mounting substrate 45.

  In addition, although cooling of the film 100 for sealing and pressurization of atmosphere may cool after pressurization, it is preferable to perform cooling and pressurization substantially simultaneously. Thereby, the film 100 for sealing can be coat | covered with the more excellent adhesiveness corresponding to the shape of the unevenness | corrugation 6. FIG.

  By passing through said process, the sealing film covering electronic component mounting board | substrate 50 with which the board | substrate 5 and the electronic component 4 were coat | covered with the film 100 for sealing can be obtained.

  Although the sealing film and the film-covered electronic component mounting substrate of the present invention have been described above, the present invention is not limited to these.

  For example, in the sealing film of the present invention, any configurations of the first and second embodiments can be combined.

  For example, the sealing film of the present invention may be added with an arbitrary layer that can exhibit the same function.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to this.

Example 1
<Manufacture of sealing film>
In order to obtain a sealing film, the following resins were prepared as resins constituting each layer of the sealing film to be formed.

That is, as the resin constituting the outermost layer 11, EVOH (manufactured by Kuraray, “EVAL SP295B”, density 1.13 g / cm ³ , melt index 5.5 g / 10 min (measured at 190 ° C.), melting point 163 ° C., ethylene content 44 Mol%).

Further, as a resin constituting the intermediate layer 13, an adhesive resin (manufactured by Mitsui Chemicals, “Admer NF536”, density 0.905 kg / m ³ , MFR 3.5 g / 10 min (190 ° C. measurement), melting point 120 ° C.) was prepared.

Further, as a resin constituting the intermediate layer 12, an ionomer resin (manufactured by Mitsui DuPont Polychemicals, “Himiran 1855”, density 0.940 kg / m ³ , MFR 1.3 g / 10 min (measured at 190 ° C.), melting point 97 ° C.) is prepared. did.

Moreover, as resin which comprises the innermost layer 14, ethylene-vinyl acetate copolymer resin (Mitsui DuPont polychemical make, "Evaflex V5714RC", density 0.940kg / m < ³ >, MFR2.8g / 10min (190 degreeC measurement), Melting point 89 ° C., vinyl acetate content 16% by weight).

  Next, the outermost layer 11 / intermediate layer is formed by coextrusion using the resin constituting the outermost layer 11, the resin constituting the intermediate layer 12, the resin constituting the intermediate layer 13, and the resin constituting the innermost layer 14. The film for sealing of Example 1 comprised with the laminated body laminated | stacked in order of 13 / intermediate layer 12 / innermost layer 14 was obtained.

  The average thickness (μm) of each layer of the obtained sealing film of Example 1 was 13/9/13/65 μm from the outermost layer 11, and the total thickness was 100 μm.

  Moreover, it was 1200% when the elongation rate in the softening point of the film for sealing of Example 1 was measured.

  Furthermore, when the linear expansion coefficient in the temperature range of 25 degreeC or more and 80 degrees C or less in the film for sealing of Example 1 was measured, it was 20 ppm / K.

Moreover, it was 2 * 10 < ⁷ > Pa when the storage elastic modulus in 80 degreeC of the film for sealing was measured.

<Manufacture of film-coated electronic component mounting substrate for sealing>
First, an arbitrary electronic component mounting board is prepared, and then the electronic component mounting board and the electronic component are covered in a chamber of a skin pack packaging machine (“HI-750 series” manufactured by Hipack). The sealing film of Example 1 obtained as described above was arranged.

  Next, the sealing film was heated and softened, and the inside of the chamber was decompressed. In addition, the temperature which heated the film for sealing was 125 degreeC, the pressure of the chamber was 0.4 kPa, and the conditions of this heating and pressure reduction were hold | maintained for 1 minute.

  Next, by returning the inside of the chamber to room temperature and normal pressure, the sealing film was cooled and the inside of the chamber was pressurized. As a result, the sealing film-covered electronic component mounting substrate of Example 1 in which the substrate and the electronic component were covered with the sealing film was obtained.

(Example 2)
The sealing film and the film-covered electronic component mounting substrate of Example 2 constituted only by the intermediate layer 13 of Example 1 were obtained.

(Example 3)
The sealing film and the film-covered electronic component mounting substrate of Example 3 configured only by the intermediate layer 12 of Example 1 were obtained.

Example 4
In order to obtain the sealing film, the following resins were prepared as the resin constituting the layer of the sealing film to be formed.

  And the film for sealing of Example 4 was obtained by extrusion method using resin which comprises this layer. In addition, the average thickness (micrometer) of the film for sealing of obtained Example 4 was 100 micrometers.

Polypropylene resin (manufactured by Sumitomo Chemical Co., Ltd., “Nobrene FS2011DG2”, density 0.900 g / cm ³ , melt index 2.0 g / 10 min (230 ° C. measurement), melting point 160 ° C.)

(Example 5)
In order to obtain the sealing film, the resin constituting each layer of the sealing film to be formed was prepared by coextrusion in the same manner as in Example 1 except that the following materials were prepared. Thus, a sealing film of Example 5 composed of a laminate in which the outermost layer 21 / intermediate layer 22 / intermediate layer 23 / innermost layer 24 were laminated in this order was obtained.

As the resin constituting the outermost layer 21, linear low density polyethylene (Ube Maruzen polyethylene, “4040FC”, density 938 g / cm ³ , melt index 3.5 g / 10 min (190 ° C. measurement), melting point 126 ° C.) is prepared. did.

  Furthermore, as a resin constituting the intermediate layer 22, a polyamide resin (manufactured by Ube Industries, “1030B2”, relative viscosity 4.1 (96% sulfuric acid), melting point 220 ° C.) was prepared.

Further, as a resin constituting the intermediate layer 23, EVOH (manufactured by Kuraray, “EVAL J171B”, density 1.18 g / cm ³ , melt index 1.7 g / 10 min (measured at 190 ° C.), melting point 183 ° C., ethylene content 32 Mol%).
Further, the same resin as the outermost layer 21 was prepared as the resin constituting the innermost layer 24.

(Comparative Example 1)
As Comparative Example 1, a commercially available biaxially stretched PET film (manufactured by Toyobo Co., Ltd., brand: E5107) was prepared.

<Evaluation test>
The sealing film or sealing film-covered electronic component mounting substrate produced in each example and comparative example was evaluated for shape followability, presence or absence of wrinkles, and heat resistance. Below, these evaluation methods are demonstrated.

<< Shape followability >>
The shape followability was evaluated as follows.

  That is, the sealing film-covered electronic component mounting substrate produced in each example and comparative example was determined based on the following evaluation criteria depending on the presence or absence of voids in the coated unevenness. The presence or absence of voids was observed using a microscope.

Each code | symbol is as follows, (circle) was set as the pass and x was set as the disqualification.
○: Covered in a filled state up to the bottom of the step ×: Covered with a clear gap formed at the bottom of the step

<< Wrinkle presence >>
The presence or absence of wrinkles was evaluated as follows.
That is, the sealing film-covered electronic component mounting substrate produced in each Example and Comparative Example was determined based on the following evaluation criteria depending on the presence or absence of wrinkles on the coated top surface. The presence or absence of wrinkles was observed using a microscope.

Each code | symbol is as follows, (circle) was set as the pass and x was set as the disqualification.
○: Wrinkles are not observed on the entire top surface of the sealing film ×: Clear wrinkles are observed at positions corresponding to the convex portions on the top surface of the sealing film

  As is clear from Table 1, in the sealing films of each example, the elongation at the softening point is 150% or more and 3500% or less, so that the voids at the bottom of the recesses, and further on the top surface of the sealing film. It was possible to coat the electronic component mounting substrate without causing wrinkles.

  On the other hand, in the sealing film of the comparative example, the elongation at the softening point is less than 150%, and as a result, when the electronic component mounting substrate is covered with the sealing film, the bottom of the recess As a result, voids and wrinkles on the upper surface of the sealing film were generated.

DESCRIPTION OF SYMBOLS 100 Film for sealing 11 Outermost layer 12 Intermediate layer 13 Intermediate layer 14 Innermost layer 4 Electronic component 5 Substrate 6 Concavity and convexity 21 Outermost layer 22 Intermediate layer 23 Intermediate layer 24 Innermost layer 45 Electronic component mounting substrate 50 Mounting film covering electronic component mounting Substrate 61 Convex part 62 Concave part

Claims (7)

A sealing film used for covering a substrate provided on an electronic component mounting substrate and an electronic component mounted on the substrate,
A sealing film comprising a resin material as a main material and having an elongation at a softening point of 150% or more and 3500% or less determined in accordance with JIS K 6251.   The sealing film according to claim 1, wherein the sealing film has a linear expansion coefficient of 100 ppm / ° C. or less in a temperature range of 25 ° C. or more and 80 ° C. or less.   The sealing film according to claim 1, wherein the sealing film has at least one layer mainly composed of a thermoplastic resin.   The sealing film according to claim 1, wherein the sealing film has an average thickness of 10 μm or more and 200 μm or less. ^5. The sealing film according to claim 1, wherein the sealing film has a storage elastic modulus at 80 ° C. of 1 × 10 ⁵ Pa or more.   The sealing film according to claim 1, wherein the substrate is a printed wiring board.   A sealing film comprising: the sealing film according to claim 1; and the substrate covered with the sealing film and an electronic component mounting substrate including the electronic component. Film-coated electronic component mounting board.

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