WO2019142423A1

WO2019142423A1 - Mounting body

Info

Publication number: WO2019142423A1
Application number: PCT/JP2018/039273
Authority: WO
Inventors: 祐輔岡部
Original assignee: セメダイン株式会社
Priority date: 2018-01-17
Filing date: 2018-10-23
Publication date: 2019-07-25
Also published as: JPWO2019142423A1; CN111566787A; TW201933556A; KR20200107994A

Abstract

The purpose of the present invention is to provide a mounting body that can ensure a reliable electrical connection between an element and conductive members electrically connected to the element, even when an external force to bend a substrate is applied, The present invention is provided with: an insulation substrate 10; an element 20 mounted on the insulation substrate 10 via conductive members 30; and covering parts 40 which cover at least a portion of side surfaces of the conductive members 30 and a side surface of the element 20, that is, at least a portion of the boundaries between the conductive members 30 and the element 20, which is provided in contact with an outer surface 10a of the insulation substrate 10, and which has an elastic modulus of 0.1 MPa to 500 MPa inclusive.

Description

Mounting body

The present invention relates to an implementation. In particular, the present invention relates to a mounting body provided with a covering portion that relieves an external force.

Conventionally, a semiconductor device having an electrode pad, a substrate having a terminal electrode, a bump electrode provided on the electrode pad of the semiconductor device, and a conductive adhesive having flexibility are provided on the bump electrode and the substrate A conductive adhesive layer electrically connected to a terminal electrode, and a composition having a viscosity of 100 Pa · s or less and a thixotropy index of 1.1 or less are cured to fill the gap between the semiconductor device and the substrate, And a sealing layer for mechanically bonding the semiconductor device, wherein the sealing material mainly comprises a resin binder and a filler, and the resin binder comprises polyepoxide, an acid anhydride and a rheology modifier There is known a mounting body which is an essential component (see, for example, Patent Document 1). According to the mounting body which concerns on patent document 1, the fluidity | liquidity of the sealing material used for flip chip mounting using a conductive adhesive agent can be improved, and the mounting body of a semiconductor device with high reliability and productivity can be implement | achieved.

Japanese Patent Application Laid-Open No. 9-64103

However, in the mounting body described in Patent Document 1, a sealing material is formed using a resin binder and a filler, and polyepoxide, an acid anhydride and a rheology modifier as essential components are used as a resin binder. Because the sealing material is hard. As a result, when an external force is applied to the mounting body described in Patent Document 1, for example, when an external force that bends the substrate is applied, damage to the sealing material or electrical connection between the semiconductor device and the conductive adhesive Problems such as disconnection may occur.

Therefore, an object of the present invention is to provide a mounting body capable of ensuring the reliability of the electrical connection between the element and the conductive member electrically connected to the element even when an external force is applied to bend the substrate. The purpose is to

In order to achieve the above object, the present invention provides an insulating substrate, an element mounted on the insulating substrate through the conductive member, at least a part of the side surface of the conductive member and the side surface of the element, There is provided a mounting body including at least a part of the boundary with the element and provided in contact with the surface of the insulating substrate and having a modulus of elasticity of 0.1 MPa or more and 500 MPa or less.

In the above-mentioned mounting body, it is preferable that the insulating base material has flexibility, and the covering portion is deformed in response to an external force.

In the mounted body described above, it is preferable that the insulating base is a flexible substrate and the conductive member is a low temperature curing conductive paste.

In the mounting body, it is preferable that the covering portion be configured using a curable composition, and the curable composition has a viscosity of 10 Pa · s or more and 100 Pa · s or less before curing.

Furthermore, in order to achieve the above object, the present invention provides an electronic device including the mounting body according to any one of the above.

Furthermore, in order to achieve the above object, the present invention provides an insulating base, an element mounted on the insulating base via a conductive member, at least a part of a side surface of the conductive member and a side surface of the element A curable composition for a covering portion of a mounting body, comprising: a covering portion covering at least a part of a region including a boundary between a member and an element and being provided in contact with a surface of an insulating substrate, the curable composition The curable composition for the coating | coated part of the mounting body whose elastic modulus after hardening of a thing is 0.1 Mpa or more and 500 Mpa or less is provided.

According to the mounting body of the present invention, the mounting body can ensure the reliability of the electrical connection between the element and the conductive member electrically connected to the element even when an external force that bends the substrate is applied. Can provide

It is a schematic diagram of a section of a mounting object concerning an embodiment of the invention. It is a schematic diagram of a test piece. It is a schematic diagram of a test method. It is a graph which shows resistance change.

<Summary of implementation>
When an element such as a semiconductor element is mounted on the insulating base using solder, the solder is provided on the surface of the insulating base, the element is mounted on the solder, and heat curing (reflow process) is performed. Then, the melted solder spreads (fillet is formed) at the contact portion between the element and the solder, and not only the portion where the element and the solder are in contact adheres, but also a part of the side of the element adheres to the solder become. As a result, the element and the insulating base are firmly bonded.

On the other hand, for example, in the case of using a flexible base or flexible substrate as the insulating base, since a solder requiring a reflow process at high temperature can not be used, a low temperature curing conductive paste is used as the conductive member. And when mounting an element using electrically-conductive members, such as a low-temperature-hardening-type electrically conductive paste, to an insulation base material, unlike solder, a fillet is not formed. Therefore, only the portion where the element and the solder are in contact adheres, and the side surface of the element does not substantially adhere to the low temperature curing conductive paste. As a result, when an external force that causes the insulating substrate to bend is applied to the insulating substrate, a part of the adhesion region between the element and the low-temperature curing conductive paste may be peeled off, which deteriorates the electrical connectivity. May. In the present embodiment, “low temperature” refers to a temperature of about 100 ° C. or less.

Therefore, the inventor has found that the element is a device that uses a base material made of a material that is easily stretched or bent, that is, when using a base material having flexibility or using a low temperature curing type conductive adhesive. From the viewpoint of maintaining the reliability of the electrical connection between the conductive member and the conductive member, at least a portion of the side surface of the conductive member and the side surface of the element, and at least a portion of the boundary between the conductive member and the element Even if the base material is stretched and / or bent by covering it with a curable composition (adhesive resin) having an elastic modulus of, and bringing the adhesive resin into contact also with the surface of the insulating base material It has been found that the electrical connectivity between the element and the conductive member can be kept good.

That is, the mounting body according to the embodiment of the present invention is at least a part of the insulating base, the element mounted on the insulating base via the conductive member, the side surface of the conductive member, and the side of the element At least a part of the boundary between the member and the element (that is, the "region including the boundary" or "the boundary end") is covered, provided in contact with the surface of the insulating substrate, and the expansion and / or contraction of the insulating substrate And a covering portion having an elastic modulus that can deform its shape in response to bending. The covering portion is formed using an adhesive resin. Here, the elastic modulus is, for example, a storage elastic modulus in dynamic viscoelasticity measurement at a frequency of 1 Hz.

<Detail of implementation>
FIG. 1 shows an outline of a cross section of a mounting body according to an embodiment of the present invention. Specifically, FIG. 1A shows an outline of a cross section of the mounting body 1 according to the present embodiment, and FIGS. 1B and 1C show an outline of a cross section of a modified example of the mounting body, respectively. Note that FIG. 1 is a schematic view, and the dimensions of the components and the ratio of the dimensions are not necessarily as illustrated.

As shown in FIG. 1A, the mounting body 1 includes an insulating base 10, an element 20 mounted on the surface 10 a of the insulating base 10 via a conductive member 30, an element 20 and a conductive member 30. Covering at least a part of the end of the boundary 50 generated in the contact part, at least a part of the side 22a of the element 20 (and / or the side of the electrode 22 described later) and at least a part of the side 30a of the conductive member 30 And a covering portion 40 for covering the area including the portion and adhering to a portion of the surface 10 a of the insulating substrate 10.

In the mounting body 1a according to the modification of FIG. 1 (b), substantially the same configuration as the mounting body 1 except that the covering portion 42 covers substantially the entire side surface of the element 20 and the side surface of the conductive member 30. And features. Further, in a mounting body 1b according to another modification of FIG. 1 (c), the mounting body 1 except that the covering portion 44 covers substantially the entire side surface and upper surface of the element 20 and the side surface of the conductive member 30. Substantially the same configuration and function as Therefore, about the mounting body 1a and the mounting body 1b, detailed description is abbreviate | omitted except the difference with the mounting body 1. FIG.

[Insulating base 10, Element 20]
The insulating substrate 10 is a substrate (insulating substrate) having an insulating property. Use various materials such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), polyimide, polypropylene (PP), polyurethane, various rubbers, etc., as the material constituting the insulating substrate 10 Can. In addition, the insulating base 10 may have flexibility or may be a flexible substrate. From the viewpoint of expansion and contraction, bending, and the like, the insulating base 10 is preferably formed of a flexible material, and is preferably a flexible substrate. In addition, since the insulation base material 10 formed using polyimide has heat resistance, solder can be used as the conductive member 30. On the other hand, in the insulating base material 10 formed using PET etc., if the solder is used as the conductive member 30, the insulating base material 10 is damaged in the mounting step (reflow process etc.). It is not possible to use a low temperature curing type conductive paste.

Examples of the element 20 include electronic elements such as semiconductor elements (including light emitting elements such as light emitting diodes and laser diodes, light receiving elements, solar cells, other sensors, and the like), chip parts, discrete parts and the like. Also, one or more elements 20 can be mounted on the insulating base 10. The element 20 has, for example, an electrode 22 at its end (for example, one electrode 22 is an electrode for the positive electrode, and the other electrode 22 is an electrode for the negative electrode). By bonding the electrode 22 and the conductive member 30, both are electrically connected, and the element 20 is bonded and fixed to the insulating base 10. Thus, the boundary 50 is also generated at the contact portion between the electrode 22 of the element 20 and the conductive member 30. In addition, the predetermined | prescribed electroconductive pattern is previously provided in the surface 10a of the insulation base material 10 (illustration is abbreviate | omitted in FIG. 1). The conductive member 30 is electrically connected to a part of the conductive pattern.

[Conductive member 30]
The conductive member 30 is a curable composition having conductivity, and is preferably a low temperature curable conductive paste. The material of the low temperature curing type conductive paste is preferably a compound which cures at a low temperature (about 100 ° C. or less), various compounds can be used, and a compound having flexibility is more preferable. The conductive member 30 has a dynamic viscoelasticity at 1 Hz from the viewpoint of maintaining the reliability of the electrical connectivity with the element 20 even when deformation such as expansion or contraction or bending is applied to the mounting body 1. The storage elastic modulus at 23 ° C. in measurement preferably has an elastic modulus of 0.1 MPa to 100 MPa.

For example, as a material of the conductive member 30, epoxy compounds, rubber compounds such as SBR, NBR, IR, BR, CR, etc., acrylic compounds, polyester compounds, polyamide compounds, polyether compounds, polyurethane compounds Polyimide compounds, silicone compounds and the like can be used. As the conductive material contained in the conductive member 30, various conductive materials can be used. Examples of conductive materials include noble metal powders such as silver, gold and palladium, base metal powders such as nickel and copper, alloy powders such as silver palladium, composite powders such as silver-plated copper powder, and carbon, etc. Non-metal powder etc. which it has can be used. These conductive materials may be used alone or in combination of two or more. In addition, the particle size and shape of these conductive materials are not particularly limited.

The curable composition having conductivity has (A) an elastomer component having a storage elastic modulus at 23 ° C. in the range of 0.1 MPa to 100 MPa in dynamic viscoelasticity measurement at 1 Hz, and (B) a conductive filler. And the (B) conductive filler may be 50% by mass or more and 85% by mass or less of the total content. Further, from the viewpoint of securing the flexibility of the cured product, (B) the conductive filler is 50% by mass or more and 85% by mass or less of the total content, and (B) the conductive filler is (b1) first And silver-plated powder, and (b2) a second silver powder and silver-plated powder. Furthermore, from the viewpoint of securing a better flexibility of the cured product, the tap density of (b1) the first silver powder and the silver-plated powder is 2.5 g / cm ³ or more and 6.0 g / cm ³ or less, (b2 ) The tap density of the second silver powder and silver-plated powder is 1.0 g / cm ³ or more and 3.0 g / cm ³ or less, and the mixing ratio of (b1) to (b2) [(b1) / (b2)] is It may be 1/10 or more and 10/1 or less in mass ratio. The conductive curable composition can also include (C) silica that has been subjected to a hydrophobization treatment with a predetermined surface treatment agent.

((A) Elastomer component whose storage elastic modulus at 23 ° C. is in the range of 0.1 MPa to 100 MPa in dynamic viscoelasticity measurement at 1 Hz)
The (A) elastomer component is an elastomer component having a storage elastic modulus at 23 ° C. in the range of 0.1 MPa to 100 MPa in dynamic viscoelasticity measurement at 1 Hz. When the storage elastic modulus at 23 ° C. is in the range of 0.1 MPa to 100 MPa in the dynamic viscoelasticity measurement at 1 Hz, a cured product which is flexible and excellent in stretchability can be obtained. Furthermore, when the storage elastic modulus at 23 ° C. in the dynamic viscoelasticity measurement at 1 Hz is in the range of 0.1 MPa to 50 MPa, it is particularly preferable because breakage hardly occurs during expansion and contraction of the cured product.

The dynamic viscoelasticity measurement of the (A) elastomer component can be measured, for example, by the following means.

When the conductive curable composition is a water dispersion, remove solid components such as (B) conductive filler and (C) silica by filtration, and then evaporate the dispersion medium by heating at 100 ° C. or less. Dynamic viscoelasticity can be measured for the cured product obtained in When the conductive curable composition is dispersed in an organic solvent (diluent), the solid component such as (B) conductive filler or (C) silica is removed by filtration, and then 150 ° C. Dynamic viscoelasticity can be measured for the cured product obtained by evaporating the dispersion medium by the following heating.

When a resin that is liquid at normal temperature, such as a modified silicone resin or urethane resin, is used as the conductive curable composition, solid components such as (B) conductive filler and (C) silica are removed by filtration. It is also possible to extract the elastomer component (A), add a curing catalyst as needed, and cure it, and measure the dynamic viscoelasticity of the resulting cured product.

With respect to the cured product of the conductive curable composition, the cured product is immersed in a solvent in which the cured product dissolves and shaken to remove solid components such as (B) conductive filler and (C) silica, and (A) Dynamic viscoelasticity can be measured on a cured product obtained by extracting the elastomer component and then removing the solvent by heating at 150 ° C. or less.

As an elastomer component having a storage elastic modulus at 23 ° C. in the range of 0.1 MPa to 100 MPa in dynamic viscoelasticity measurement at 1 Hz, conventionally known resins and rubbers can be used. For example, thermoplastic resins and thermosetting resins Materials formed from water soluble resins, crosslinked rubbers, and vulcanized rubbers. Examples of such resin include vinyl resin, acrylic resin, butadiene resin, silicone resin, polyurethane resin, modified silicone resin, and the like. Further, the above resin may be used as a water dispersion.

For example, vinyl resins include vinyl acetate polymer resins, vinyl chloride / vinyl acetate copolymer resins, vinyl chloride / vinyl acetate / maleic acid terpolymer resins, or combinations thereof.

Moreover, as an acrylic elastomer as an acrylic resin, for example, glass transition temperatures (T _g ) of polybutyl (meth) acrylate, poly 2-ethylhexylethyl (meth) acrylate, poly 2-hydroxyethyl (meth) acrylate, etc. are compared. Resins, or combinations thereof. In addition to these skeletons, block copolymers containing polymethyl (meth) acrylate are preferable from the viewpoint of securing elongation physical properties and adhesiveness while maintaining flexibility.

As the block copolymer, various block copolymers can be used. For example, an acrylic triblock copolymer produced by a living polymerization method can be used. Specifically, polymethyl methacrylate-polybutadiene-polystyrene copolymer, polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate copolymer, these copolymers were subjected to carboxylic acid modification treatment or hydrophilic group modification treatment Block copolymers such as copolymers, polymethyl methacrylate-polybutyl acrylate copolymers, and polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate copolymers can be used.

Examples of the butadiene-based resin include SB (styrene-butadiene) resin, SBS (styrene-butadiene-styrene) resin, SEBS resin (styrene-ethylene / butylene-styrene), SIS (styrene-isoprene-styrene) resin, SIBS (SIBS) Styrene-isoprene / butadiene-styrene) resins, SEPS (styrene-ethylene / propylene-styrene) resins, etc., or combinations thereof.

As the modified silicone resin, conventionally known crosslinkable silicon group-containing organic polymers can be used. The crosslinkable silicon group of the crosslinkable silicon group-containing organic polymer is a group which has a hydroxyl group or a hydrolyzable group bonded to a silicon atom and can be crosslinked by forming a siloxane bond.

((B) conductive filler)
The conductive filler is formed using a material having electrical conductivity. As the conductive filler, for example, silver powder, copper powder, nickel powder, aluminum powder, and silver plated powder thereof, metal powder such as silver coated glass, silver coated silica, silver coated plastic, etc .; zinc oxide, titanium oxide, ITO , ATO, carbon black and the like. From the viewpoint of reducing the volume resistivity, the conductive filler is preferably silver powder or silver plating powder, and it is more preferable to use silver powder and silver plating powder in combination from the viewpoint of conductivity reliability and cost.

(B) As the shape of the conductive filler, various shapes (for example, granular, spherical, elliptical, cylindrical, flake, flat, or agglomerates) can be adopted. The conductive filler can also have a somewhat rough or jagged surface. The particle shape, size, and / or hardness of the conductive filler can be used in combination in the curable composition having conductivity. In addition, for the purpose of further improving the conductivity of the cured product of the conductive curable composition, a plurality of conductive fillers having different particle shapes, sizes, and / or hardness of (B) conductive filler are combined. It can also be done. In addition, the conductive filler to be combined is not limited to two types, and may be three or more types. Among them, it is preferable to use a flaky conductive filler and a particulate conductive filler in combination.

Here, the flake shape includes a flat shape, a flaky shape, or a scaly shape, and includes a shape obtained by crushing silver powder having a three-dimensional shape such as a spherical shape or a massive shape in one direction. Moreover, a granular form means the shape of all the electroconductive fillers which do not have flake shape. For example, as the granular form, there may be mentioned a shape in which powder is aggregated into a bunch of grapes, a spherical shape, a substantially spherical shape, a massive shape, a dendritic shape, or a mixture of silver powder having these shapes.

Moreover, when using silver powder and silver plating powder as (B) electroconductive filler, this electroconductive filler can be manufactured by various methods. For example, when flake-like silver powder is used as a conductive filler, it is manufactured by mechanically pulverizing silver powder such as spherical silver powder, massive silver powder, and / or granular silver powder using an apparatus such as a jet mill, roll mill or ball mill. it can. When granular silver powder is used as a conductive filler, it can be produced by an electrolytic method, a pulverizing method, a heat treatment method, an atomizing method, a reduction method or the like. Among these, the reduction method is preferable because a powder with a low tap density can be easily obtained by controlling the reduction method.

(B) As silver powder and silver plating powder used for a conductive filler, well-known silver powder and silver plating powder can be used widely. The silver powder and the silver-plated powder preferably include (b1) the first silver powder and the silver-plated powder and (b2) the second silver powder and the silver-plated powder each having a predetermined tap density. The mixing ratio [(b1) / (b2)] of (b1) and (b2) is 1/10 or more and 10/1 or less in mass ratio, preferably 1/4 or more and 4/1 or less, and 3/2 or more 4/1 or less is more preferable. Moreover, in the component (b1), the mixing ratio of the first silver powder and the silver plating powder is 1/10 or more and 10/1 or less, and in the component (b2), the mixing ratio of the second silver powder and the silver plating powder Is 1/10 or more and 10/1 or less.

(B1) The tap density of the first silver powder and silver-plated powder is less than 2.5 g / cm ³ or more ^{6.0g / cm 3, 3.0g / cm} 3 or more 5.0 g / cm ³ or less. Moreover, as for the 50-% average particle diameter of (b1) 1st silver powder, 0.5 micrometer or more and 15 micrometers or less are preferable. The shape of the (b1) first silver powder and the silver-plated powder may be various shapes, and various shapes such as flakes and particles can be used. Among them, flake-like silver powder and silver-plated powder are preferable.

The tap density of silver powder and silver-plated powder can be measured by the method according to the 20.2 tap method of JIS K 5101-1991. Moreover, 50% average particle diameter is a particle diameter in 50% of the volume accumulation measured by laser diffraction scattering type particle size distribution measuring method.

(B2) The tap density of the second silver powder and the silver-plated powder is 1.0 g / cm ³ or more and 3.0 g / cm ³ or less. Moreover, as for the 50% average particle diameter of (b2) 2nd silver powder and silver plating powder, 0.5 micrometer or more and 20 micrometers or less are preferable. In addition, the shapes of (b2) 2nd silver powder and silver plating powder may be various shapes, and various shapes, such as flake shape and a granular form, can be used. Among them, granular silver powder and silver plated powder are preferable.

The content of the conductive filler (B) is 50% by mass to 85% by mass, preferably 65% by mass to 85% by mass, and preferably 70% by mass to 80% by mass of the total content of the conductive curable composition. % Or less is more preferable. From the viewpoint of obtaining sufficient conductivity, the content is preferably 50% by mass or more, and from the viewpoint of securing adhesiveness and workability together with excellent conductivity, it is preferably 85% by mass or less. In particular, from the viewpoint of securing adhesiveness and workability, it is preferable that the content of the (b2) second silver powder and the silver-plated powder is not excessively increased.

When the tap density of the components (b1) and (b2) is within the above range, sufficient conductivity can be exhibited without adding a large amount of silver powder and silver plating powder. From the viewpoint of cost control, in particular, one of the components (b1) and (b2) is a flake-like silver powder and / or a silver-plated powder, and the other is a combination of granular silver powder and / or a silver-plated powder. It is preferable to use it.

((C) silica)
By using one or more types of silica selected from the group consisting of hydrophobic silica hydrophilized with a specific surface treatment agent (C) and hydrophilic silica together with component (A) and component (B), it becomes possible to conduct electricity in particular It is possible to obtain a conductive curable composition excellent in the stability of the properties. The particle size of (C) silica is not particularly limited, but fine silica powder is preferable, fine silica powder having an average particle size of 7 nm to 16 nm is more preferable, and fine silica powder having an average particle size of 7 nm to 14 nm is most preferable.

Well-known hydrophilic silica can be widely used as hydrophilic silica, and fumed silica having a silanol group (Si-OH group) on the surface is preferable among them. By using hydrophilic silica, it is possible to prevent bleeding while securing flowability without increasing viscosity. The conductive curable composition having flowability is suitable for applications requiring flowability, for example, application to a substrate by screen printing and formation of a pattern with a thin film of about 50 μm.

As hydrophobic silica, one or more surface treatment agents selected from the group consisting of dimethyldichlorosilane, hexamethyldisilazane, (meth) acrylsilane, octylsilane (eg, trimethoxyoctylsilane etc.), and aminosilane Hydrophobicized hydrophobic silica is used. By using hydrophobic silica hydrophobized with such a specific surface treatment agent, it is possible to prevent bleeding while ensuring dischargeability and shape retention. The conductive curable composition having a shape retention property is required to have a film thickness of 100 μm or more when the shape retention property is required, for example, in the case of forming a pattern by applying to a substrate by a screen printing method, The present invention is suitable for applications such as replacing the solder connection portion with a conductive curable composition.

The hydrophobization treatment method of the silica using a surface treatment agent can select a well-known method, for example, the surface treatment agent mentioned above is sprayed on untreated silica, or the surface treatment agent which vaporized is mixed, and heat treatment is carried out. Methods are included. In addition, it is preferable to process this hydrophobization by the dry condition under nitrogen atmosphere.

Although the compounding ratio of (C) component does not have a restriction | limiting in particular, It is preferable to use 3 mass parts or more and 20 mass parts or less with respect to 100 mass parts of (A) component, and it is more preferable to use 5 mass parts or more and 10 mass parts or less . (C) Silica can be used alone or in combination of two or more.

(Other additives)
In the conductive curable composition, from the viewpoint of adjusting the viscosity, physical properties, and the like within the range that does not impair the functions such as the conductivity and the curing property of the conductive curable composition, a curing catalyst, a filler, and a plastic as needed. Agent, adhesion promoter, stabilizer, coloring agent, physical property modifier, thixotropic agent, dehydrating agent (storage stability improving agent), tackifier, anti-sagging agent, ultraviolet absorber, antioxidant, flame retardant, radical A substance such as a polymerization initiator or various solvents such as toluene and alcohol may be blended. Also, other polymers compatible may be blended.

The curable composition having conductivity can be made into a one-component type as needed, and can also be made a two-component type. The curable composition having conductivity is particularly suitable for use as a one-component type. Moreover, since the curable composition which has electroconductivity is hardened | cured at normal temperature by the humidity in air | atmosphere, it is suitable to use as a normal temperature moisture hardening type conductive adhesive. In the effect of the curable composition having conductivity, curing may be promoted by heating (for example, heating at about 80 ° C. to 100 ° C.) as appropriate.

A conductive curable composition has high conductivity by being applied or printed on a substrate and cured, and can be used instead of solder. In addition, the curable composition having conductivity is used for bonding and mounting of electronic parts such as semiconductor element chip parts and discrete parts, circuit connection, bonding / fixing of crystal oscillators and piezoelectric elements, sealing of packages, etc. It is suitable for. It is also possible to form on the surface of the substrate a circuit in which one or more kinds of electronic components such as semiconductor elements, chip parts, discrete parts and the like are joined using a curable composition having conductivity.

Further, since the cured product of the conductive curable composition that constitutes the conductive member 30 according to the present embodiment has flexibility, it is provided on the surface of the insulating base 10 with a predetermined pattern. In this case, even if deformation such as expansion and contraction or bending is applied to the insulating base material 10, the insulating base material 10 is freely deformed according to the deformation.

[Cover 40]
The covering portion 40 adheres to at least a part of the side surface of the element 20 and to at least a part of the side surface of the conductive member 30 and is adhered to the surface 10 a of the insulating substrate 10. The covering portion 40 functions as a pseudo fillet, but has no conductivity. Accordingly, a) the adhesion to the conductive member 30 is good, and b) the material constituting the cover 40 does not penetrate into the conductive member 30 (if it penetrates, the conductive member 30 The resistance value may increase) c) Characteristics such as being able to reduce distortion between the element 20 and the conductive member 30 even when an external force such as expansion or contraction or bending is applied to the mounting body 1 are required. Be done.

The covering portion 40 has an elastic modulus of 0.1 MPa or more from the viewpoint of securing appropriate flexibility and electric reliability, and the elastic modulus is preferably 1 MPa or more, more preferably 5 MPa or more. In addition, the covering portion 40 has an elasticity of 500 MPa or less from the viewpoint of reducing the strain generated in the mounting body 1 when an external force is applied to the mounting body 1 and maintaining the durability (the conductivity decreases with time). The modulus of elasticity is preferably 200 MPa or less, more preferably 100 MPa or less. The covering portion 40 has the above elastic modulus and can be deformed in response to an external force. The elastic modulus is a storage elastic modulus in dynamic viscoelasticity measurement at a frequency of 1 Hz.

And as a curable composition (it may be called "adhesive resin" in this embodiment) which comprises the coating | coated part 40, the barrier property with respect to adhesiveness, heat resistance, a water | moisture content, oxygen, etc. is considered, and various Compounds can be used. For example, in addition to silicone resin, acrylic resin, and methacrylic resin, the covering unit 40 may be a curable adhesive such as various thermosetting adhesives, photocurable adhesives, or two-component mixed curable adhesives. It can be configured using. From the viewpoint of preventing the curable composition from spreading more than necessary when dropped onto the insulating substrate 10 before forming the covering portion 40 (that is, before curing the curable composition), It is preferable to have a viscosity of 10 Pa · s or more and 100 Pa · s or less. Moreover, when forming the coating | coated part 40, you may harden | cure a curable composition to a sheet form previously, and may utilize. The sheet-like covering portion 40 can be appropriately formed by a known method.

[Method of manufacturing mounting body 1]
The mounting body 1 can be manufactured, for example, through the following steps. First, the insulation base material 10 in which the predetermined | prescribed conductive pattern was previously provided in the surface 10a is prepared (insulation base material preparatory process). Next, a conductive curable composition that will constitute the conductive member 30 is applied or printed in a region on the conductive pattern where the device 20 is to be mounted and where the electrode 22 of the device 20 is to be disposed ( Printing process). Subsequently, the element 20 is placed on the conductive curable composition (placement step). Then, the curable composition is cured at a normal temperature (for example, 23 ° C.) or a low temperature (for example, a temperature of 100 ° C. or less) (curing step). Thereby, the element 20 is fixed on the insulating base 10.

Then, the curable composition which will comprise the coating | coated part 40 is apply | coated to at least one part area | region of the circumference | surroundings of the element 20, and this curable composition is hardened at normal temperature or low temperature. In this case, the application amount of the curable composition is adjusted to an amount in which the boundary 50 between the element 20 and the conductive member 30 is covered and the side surface of the conductive member 30 is covered. Thereby, the covering part 40 is formed (covering part formation process). Through the above steps, the mounting body 1 is manufactured.

In the mounting body 1a, the coating amount of the curable composition is adjusted to an amount such that substantially all of the side surface of the element 20 and the side surface of the conductive member 30 are covered in the covering portion forming step. Similarly, in the mounting body 1b, the amount of the curable composition applied is adjusted to an amount such that the entire element 20 is covered in the covering portion forming step.

The mounting body 1 can be applied to various electronic devices such as, for example, printed electronics, wearable devices, robots, electronic devices including machines having a movable range, and the like.

<Effect of the embodiment>
In the mounting body 1 according to the present embodiment, a region including the boundary 50 between the element 20 and the conductive member 30 is covered by the covering portion 40 having a predetermined elastic modulus, and the covering portion 40 is formed of the insulating substrate 10. It also adheres to the surface 10a. Therefore, not only when the insulating base material 10 is bent but also when it is expanded and contracted, since the covering portion 40 relieves the stress generated by the bending and expansion and contraction, the electrical connectivity between the element 20 and the conductive member 30 can be improved. Can be maintained. As a result, according to the mounting body 1, the reliability of the electrical connectivity between the element 20 and the conductive member 30 can be maintained.

The reliability of the electrical connectivity is equal between the case where solder is used as the conductive member 30 and the case where a low temperature curing type conductive paste is used when the mounting body 1 is bent. On the other hand, when the mounting body 1 is expanded and contracted, the reliability in the case of using the low temperature curing type conductive paste is superior to the case of using the solder. This is because although the low temperature curing type conductive paste expands and contracts according to the expansion and contraction force, the solder does not expand and contract.

In particular, when a flexible substrate is used as the insulating substrate 10, a circuit can be formed on the flexible substrate by printing, so adjustment of the resistance value in the circuit is easy, and the number of components can be reduced. And since important parts such as IC are "hard", the covering portion 40 is provided on the part where such "hard" electronic parts are to be provided, so that the reliability as a whole of the mounting body 1 (reliability of electrical connectivity, operation Reliability etc. can be improved.

Hereinafter, the present invention will be described in more detail by way of examples. Needless to say, these examples are illustrative and should not be construed as limiting.

FIG. 2 shows an outline of a test piece according to an example. Specifically, FIG. 2 (a) shows a top view of the flexible substrate 11 constituting the test piece, and FIG. 2 (b) shows a state in which the conductive adhesive 32 is printed on the flexible substrate 11, FIG. (C) shows an outline of a cross section of a test piece according to Example 1.

Example 1
As shown to Fig.2 (a), the flexible substrate 11 in which the copper wiring 14 (5 mm) was formed on the polyimide film 12 (thickness 12.5 micrometers) was prepared. In addition, two copper wirings 14 are provided on the polyimide film 12, and a 0.6 mm gap is provided between one copper wiring 14 (length: 45 mm) and the other copper wiring 14 (length: 127 mm). Provided.

Then, as shown in FIG. 2 (b), using a metal mask (aperture 1 mm × 0.8 mm, thickness 100 μm), the conductive adhesive is attached to the chip mounting portion (the end on the gap side of each copper wiring 14). The agent 32 was printed, and a resistive chip 24 (0 Ω) equipped with a gold-plated electrode of 1608 size was mounted as shown in FIG. 2 (c). Subsequently, the conductive adhesive 32 was cured at 80 ° C. for 60 minutes. Furthermore, a curable composition (Super X Gold No. 777 clear. Cemedine Co., Ltd.) is provided in the portion connected by the conductive adhesive 32 (including the portion covering the boundary edge between the resistive chip 24 and the conductive adhesive 32). 1 mg) and aged for 24 hours under an environment of 23.degree. C. and 50% RH to form a coated portion 42. Thus, a test piece according to Example 1 was obtained.

The conductive adhesive 32 was prepared using the acrylic acid ester-based polymer A1 synthesized in Synthesis Example 1 below, and adding each of the compounding materials at the mixing ratio shown in Table 1. Specifically, each of the component (A), the component (B), and the other additives was weighed and prepared so as to obtain the mixture ratio shown in Table 1. Next, they were mixed and stirred. Thus, a conductive adhesive 32 was obtained.

Synthesis Example 1
40 parts by mass of ethyl acetate as a solvent, 59 parts by mass of methyl methacrylate, 25 parts by mass of 2-ethylhexyl methacrylate, 22 parts by mass of γ-methacryloxypropyltrimethoxysilane, and 0.1 parts by mass of ruthenocene dichloride as a metal catalyst Charge and heat to 80 ° C. while introducing nitrogen gas. Then, 8 parts by mass of 3-mercaptopropyltrimethoxysilane was added into the flask and reacted at 80 ° C. for 6 hours. After cooling to room temperature, 20 parts by mass of a benzoquinone solution (95% THF solution) was added to terminate the polymerization. A solvent and an unreacted material are distilled off, and an acrylic acid ester polymer A1 having a trimethoxysilyl group having a polystyrene equivalent mass average molecular weight of about 6,000 and a glass transition point (Tg) of 61.2 ° C. I got

In Table 1, the unit of the compounding amount of each compounding substance is "mass part". Moreover, the details of the compounding substance are as follows.
* 1: Urethane polymer with hydrolyzable silicon group (trade name: "SPUR + 1050MM", manufactured by Momentive)
* 2 Flaky silver powder, trade name: Silcoat AgC-B, manufactured by Fukuda Metal Foil & Powder Co., Ltd., specific surface area 1.35 m ² / g, tap density 4.6 g / cm ³ , 50% average particle diameter 4 μm.
* 3) Granular silver powder (reduced powder), trade name: Silcoat AgC-G, manufactured by Fukuda Metal Foil & Powder Co., Ltd., specific surface area 2.5 m ² / g, tap density 1.4 g / cm ³ .
* 4) Phenolic antioxidant, trade name Irganox 245, manufactured by BASF.
* 5) Amine based anti-aging agent, trade name Tinubin 765, manufactured by BASF.
* 6) Hydrophilic silica, trade name: Leorosil QS-20, manufactured by Tokuyama Corporation.
* 7) Paraffin based diluent, trade name: Cactus Normal Paraffin N-11, Japan Energy Co., Ltd.
* 8) Vinyltrimethoxysilane, trade name: KBM-1003, manufactured by Shin-Etsu Chemical Co., Ltd.
* 9) Dioctyltin compound, trade name: Neostan U-830, manufactured by Nitto Kasei Co., Ltd.

(Comparative Example 1, Reference Example 1)
The test piece according to Comparative Example 1 was produced in the same manner as in Example 1 except that the coating portion 42 was not formed, unlike in Example 1. In the test piece according to the first embodiment, the conductive adhesive 32 is a solder paste (FLF01-BZ (L), manufactured by Matsuo Solder Co., Ltd.), and the coating 42 is not formed. It produced similarly. In Reference Example 1, the solder paste was reflowed by heating at 260 ° C. for 5 minutes.

(Example 2)
A test piece according to Example 2 was produced in the same manner as Example 1, except that the polyimide film 12 was changed to a PET film, unlike Example 1. In addition, since the PET film was damaged by heating at 260 ° C. for 5 minutes, a test piece using solder as a conductive member could not be produced.

(Conductivity after U-shaped folding test)
FIG. 3 shows an outline of the U-shaped folding test.

As shown in FIG. 3, lead wires were connected to both ends of the test piece 2 according to the example 1 using a kapton tape 60 and set in a U-shaped folding tester (DLDMLH-4U, manufactured by Yuasa System Instruments Co., Ltd.) . As for the U-shaped folding test conditions, the bending radius was set to 10 mm, the test stroke was ± 40 mm, and the test speed was set to 30 rpm. Then, at the same time as the operation of the testing machine, 10,000 U-shaped folding tests were performed using a resistance meter (RM 3544, Hioki Electric Co., Ltd.) and resistance measurement was simultaneously performed. The same test was conducted on Comparative Example 1 and Reference Example 1. The results are shown in FIG. The U-shaped return test is a test in which the sample is continuously moved horizontally and bent in accordance with test conditions set in advance.

As can be seen with reference to FIG. 4, in the test piece according to Example 1, it was observed that the resistance value was similar to that of the solder and that there was almost no change in the resistance value even when the test piece was bent. On the other hand, in Comparative Example 1, it was observed that the resistance value increased significantly from the beginning of bending and gradually increased as the number of bendings increased. Thereby, as shown in the test piece according to Example 1, the usefulness of the covering portion 42 in the case of using the low temperature curing type conductive paste was shown. Moreover, in the test piece which concerns on Example 2, the result similar to Example 1 was obtained (illustration in FIG. 4 is abbreviate | omitted).

Although the embodiments and examples of the present invention have been described above, the embodiments and examples described above do not limit the invention according to the claims. In addition, not all combinations of features described in the embodiments and examples are essential to the means for solving the problems of the invention, and various combinations without departing from the technical concept of the invention. It should be noted that variations are possible.

DESCRIPTION OF

SYMBOLS

1, 1a, 1b mounting body 2 test piece 10 insulation base material 10a surface 11 flexible substrate 12 polyimide film 14 copper wiring 20 element 22 electrode 22a side 24 resistance chip 30 conductive member 30a side 32

conductive adhesive

40, 42, 44 coating Part 50 Boundary 60 Kapton Tape

Claims

An insulating substrate,
An element mounted on the insulating base via a conductive member;
At least a portion of the side surface of the conductive member and the side surface of the element, covering at least a portion of the boundary between the conductive member and the element, is provided in contact with the surface of the insulating substrate, and has an elastic modulus A mounting body provided with the covering part which is 0.1 or more MPa and 500 or less MPa.
The insulating substrate is flexible,
The mounting body according to claim 1, wherein the covering portion is deformed in response to an external force.
The insulating substrate is a flexible substrate,
The mounting body according to claim 1, wherein the conductive member is a low temperature curing conductive paste.
The covering portion is configured using a curable composition,
The mounting body according to any one of claims 1 to 3, wherein the curable composition has a viscosity of 10 Pa · s or more and 100 Pa · s or less before curing.
An electronic device comprising the mounting body according to any one of claims 1 to 4.
An insulating substrate,
An element mounted on the insulating base via a conductive member;
A coating that covers at least a portion of the side surface of the conductive member and the side surface of the element, at least a portion of the region including the boundary between the conductive member and the element, and is provided in contact with the surface of the insulating substrate A curable composition for a cover of a mounting body comprising:
The curable composition for the coating | coated part of the mounting body whose elastic modulus after hardening of the said curable composition is 0.1 Mpa or more and 500 Mpa or less.