CN101952902B - Conductive paste, electromagnetic wave-shielding film using same, and electromagnetic wave-shielding flexible printed wiring board - Google Patents

Conductive paste, electromagnetic wave-shielding film using same, and electromagnetic wave-shielding flexible printed wiring board Download PDF

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Publication number
CN101952902B
CN101952902B CN2009801051008A CN200980105100A CN101952902B CN 101952902 B CN101952902 B CN 101952902B CN 2009801051008 A CN2009801051008 A CN 2009801051008A CN 200980105100 A CN200980105100 A CN 200980105100A CN 101952902 B CN101952902 B CN 101952902B
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paste
conduction
isocyanate
urethane
stuck
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CN101952902A (en
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下田浩平
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Sumitomo Electric Industries Ltd
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20Conductive material dispersed in non-conductive organic material
    • H01B1/22Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00Printed circuits
    • H05K1/02Details
    • H05K1/09Use of materials for the conductive, e.g. metallic pattern
    • H05K1/092Dispersed materials, e.g. conductive pastes or inks
    • H05K1/095Dispersed materials, e.g. conductive pastes or inks for polymer thick films, i.e. having a permanent organic polymeric binder
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073Shielding materials
    • H05K9/0081Electromagnetic shielding materials, e.g. EMI, RFI shielding
    • H05K9/0083Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive non-fibrous particles embedded in an electrically insulating supporting structure, e.g. powder, flakes, whiskers
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073Shielding materials
    • H05K9/0094Shielding materials being light-transmitting, e.g. transparent, translucent
    • H05K9/0096Shielding materials being light-transmitting, e.g. transparent, translucent for television displays, e.g. plasma display panel
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00Printed circuits
    • H05K1/02Details
    • H05K1/0213Electrical arrangements not otherwise provided for
    • H05K1/0216Reduction of cross-talk, noise or electromagnetic interference
    • H05K1/0218Reduction of cross-talk, noise or electromagnetic interference by printed shielding conductors, ground planes or power plane
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00Printed circuits
    • H05K1/02Details
    • H05K1/03Use of materials for the substrate
    • H05K1/0393Flexible materials
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/01Dielectrics
    • H05K2201/0137Materials
    • H05K2201/0145Polyester, e.g. polyethylene terephthalate [PET], polyethylene naphthalate [PEN]

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Electromagnetism (AREA)
  • Conductive Materials (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
  • Parts Printed On Printed Circuit Boards (AREA)
  • Non-Insulated Conductors (AREA)

Abstract

A conductive paste containing a conductive metal powder, a urethane-modified polyester resin and a block isocyanate, wherein the urethane-modified polyester resin is obtained by reacting an acid component, an alcohol component and an isocyanate component containing an aromatic isocyanate, and the total of the aromatic components contained in the acid component, alcohol component and isocyanate component is not less than 5 mol% but not more than 50 mol% of the total of the acid component, alcohol component and isocyanate component. The conductive paste has a good balance between flexibility and heat resistance, and is capable of forming a shielding layer having excellent bending resistance. An electromagnetic wave-shielding film using the conductive paste and an electromagnetic wave-shielding flexible printed wiring board are also disclosed.

Description

Electromagnetic shielding film and electromagnetic shielding flexible printing wiring board that conduction is stuck with paste and used this conduction to stick with paste
Technical field
The present invention relates to conduction and stick with paste, and the electromagnetic shielding film and the electromagnetic shielding flexible printing wiring board that use this conduction to stick with paste, more specifically, the present invention relates to have the flexible printing wiring board of resistance to bend(ing).
Background technology
Through with conductive filler such as carbon black, graphite powder, precious metal powder, copper powder or nickel powder, adhesive resin and solvent, conduction is pasted into thickener.Through methods such as silk screen printings, the conduction paste is applied on film or the substrate to realize the formation of pattern.Make resin solidification, thereby form conducting wiring.Recently, along with the miniaturization and the lightweight of electronic component, the conduction paste that need have high conductivity is used for this application.
Patent documentation 1 discloses and has used the conductive silver paste of silver as conductive filler.Example as the shape of the silver powder of conductive filler includes but not limited to: granular, flakey, tabular, dendroid, grain is granular and the square shape.Using granularity is the silver powder of 0.1 to 100 μ m.The mylar and the blocked isocyanate that use saturated combined polymerization are as adhesive resin.Patent documentation 2 discloses; In order to improve the resistance to bend(ing) that conduction is stuck with paste; Use following conduction to stick with paste, it mainly contains: wherein granularity is that three-dimensional silver powder, the number-average molecular weight that connects of primary generation of 0.1~5 μ m is adhesive, curing agent and solvent more than 3000.The example of adhesive comprises polyurethane resin and mylar.
Conduction is stuck with paste also as electromagnetic shielding material.Especially, the frequency in the high frequency band is used to transmit at a high speed information now.This conduction that need have better capability of electromagnetic shielding is stuck with paste.Patent documentation 3 discloses the conductive silver paste of conductivity with improvement and shielding and has used the electromagnetic shielding film of this conductive silver paste, and said conductive silver paste is processed through the silver powder that combination has specified particle size.
Summary of the invention
Technical problem to be solved by this invention
Stick with paste when being used for the screen of flexible printing wiring board when conducting electricity, except conductivity and capability of electromagnetic shielding, the screen through coating and the formation of curing conductive paste also need have thermal endurance, surface smoothing property and resistance to bend(ing).Particularly, when using it for the hinge portions of moving part such as mobile phone, the miniaturization of machine need be in the durability than the small-bend radius place.Therefore, its purpose is to improve resistance to bend(ing).
In the described conductions of patent documentation 3 are stuck with paste, put down in writing preferred use mylar as adhesive resin to average out between thermal endurance in coating, after solidifying and the flexibility.Yet,, must further improve resistance to bend(ing) in order to reach current required resistance to bend(ing).
In order to improve resistance to bend(ing), need flexibility.The mylar that therefore, will belong to barras is as adhesive resin.Mylar is the resin that the polycondensation through sour composition such as polyvalent carboxylic acid or acid anhydrides and pure composition such as polyalcohol prepares.The kind of choosing sour composition and pure composition is control characteristic suitably.For example, the use of a large amount of soft components such as aliphatic dicarboxylic acid can improve flexibility.Yet, use a large amount of soft components can reduce thermal endurance, thereby can not satisfy desired properties.In order to improve thermal endurance, must increase the aromatic component of rigidity such as the ratio of terephthalic acid (TPA).In this case, reduced flexibility.
Consider the problems referred to above, the objective of the invention is that provide the conduction that can form electro-magnetic screen layer to stick with paste and use the electromagnetic shielding film of this conduction paste, said electro-magnetic screen layer averages out, and has excellent resistance to bend(ing) between flexibility and thermal endurance.
The means of dealing with problems
Said conduction is stuck with paste and is comprised conductive metal powder, urethane-modified mylar and blocked isocyanate; Wherein urethane-modified mylar makes through the isocyanate prepolymer composition reaction that makes sour composition, pure composition and contain aromatic isocyanate, and the total amount of the aromatic component that contains in sour composition, pure composition and the isocyanate prepolymer composition is the 5mol% to 50mol% (first invention) of the total amount of sour composition, pure composition and isocyanate prepolymer composition.
To be used as adhesive resin with the urethane-modified polyester of the isocyanate prepolymer composition modification that contains aromatic isocyanate.And the total amount of the aromatic component that contains in sour composition, pure composition and the isocyanate prepolymer composition is the 5mol% to 50mol% of the total amount of said sour composition, pure composition and isocyanate prepolymer composition.This molecular structure is obtained good balance between flexibility that resistance to bend(ing) needs and thermal endurance.
Said urethane-modified mylar preferably has the hydroxyl value (second invention) of 5mg KOH/g to 60mgKOH/g.Hydroxyl value is the index with respect to the molecular weight of crosslinking points (with the hydroxyl of blocked isocyanate reaction) quantity of urethane-modified mylar.Higher hydroxyl value causes molecular weight lower.Lower hydroxyl value causes molecular weight higher.Hydroxyl value less than 5mg KOH/g causes HMW and excellent flexibility, but also causes tailing off with the required crosslinking points quantity of blocked isocyanate reaction, thereby thermal endurance is reduced.On the contrary, the hydroxyl value above 60mg KOH/g causes molecular weight to reduce.In this case, though improved thermal endurance, reduced flexibility.
Blocked isocyanate preferably has 500~3000 number-average molecular weight; And be polyfunctional blocked polyisocyanates compound; Wherein use end-capping reagent will add the end-capped of mould assembly isocyanates, the said mould assembly isocyanates that adds forms (the 3rd invention) by isocyanate-monomer and polyol.Add the mould assembly isocyanates and in its molecule, have a lot of functional groups (NCO), thereby increased the crosslink density of reacted urethane-modified mylar, and improve thermal endurance.
Convert with the NCO (NCO) of the blocked isocyanate mol ratio (NCO/OH) to the hydroxyl (OH) of urethane-modified mylar, said blocked isocyanate is preferably 0.8~3.0 (the 4th invention) to the mixing ratio of said urethane-modified mylar.If the amount of blocked isocyanate is lower than above-mentioned scope, then urethane-modified mylar has low crosslink density and low heat resistant.If the amount of blocked isocyanate surpasses above-mentioned scope, the isocyanates of not participating in so reacting can remain in the adhesive resin, thereby reduces thermal endurance.Said mol ratio is more preferably in 1.0~2.0 scope.
Conductive metal powder is that metal dust A and the particle mean size of 0.5 μ m to 20 μ m is that metal dust B below the 100nm forms by particle mean size preferably; Said metal dust A is 99.5: 0.5 to 70: 30 to the weight content ratio of said metal dust B, and the content ratio of the solid state component of conductive metal powder foot couple conduction paste is 50 weight % to 85 weight % (the 5th inventions).Higher conductive metal powder content ratio causes conductivity to be improved.Yet the content of conductive metal powder causes conducting electricity the flexibility of sticking with paste and descends than too high, thereby resistance to bend(ing) is worsened.Therefore, in order between conductivity and resistance to bend(ing), to average out, the content ratio of conductive metal powder is preferably 50 weight % to 85 weight %.
In order to reach satisfied conductivity, preferably use than combination to have varigrained said metal dust A and said metal dust B with certain content.The said metal dust B filling of use nanoscale has than the gap between the particle of the said metal dust A of coarsegrain, thereby improves the surface smoothing property behind conductivity and the muddled cloth of conduction.Surface smoothing property and conductivity influence capability of electromagnetic shielding.Therefore, improve conductivity and surface smoothing property and cause further raising capability of electromagnetic shielding.
The present invention also provides electromagnetic shielding film, and it is included in the layer (the 6th invention) that is pasted by above-mentioned conduction on the base material.And, the invention provides the electromagnetic shielding flexible printing wiring board, it comprises the layer (the 7th invention) that is pasted by above-mentioned conduction.Except the resistance to bend(ing) of excellence, electromagnetic shielding film and electromagnetic shielding flexible printing wiring board all also have excellent thermal endurance, conductivity and capability of electromagnetic shielding.
The invention effect
According to the present invention, can provide: the conduction that can form electro-magnetic screen layer is stuck with paste, and said electro-magnetic screen layer averages out between flexibility and thermal endurance, and has excellent resistance to bend(ing); The electromagnetic shielding film and the electromagnetic shielding flexible printing wiring board that use this conduction to stick with paste.
Description of drawings
Fig. 1 is the cross sectional representation of electromagnetic shielding film of the present invention.
Fig. 2 is the cross sectional representation of electromagnetic shielding flexible printing wiring board of the present invention.
Embodiment
The various details execution mode.In description of drawings, use prosign to represent same key element, and omit repeat specification.Size ratio in the accompanying drawing is always more consistent than not with the size of the actual object that each figure describes.
With describing the urethane-modified mylar that the present invention uses.Said urethane-modified mylar makes through making sour composition, pure composition and isocyanate prepolymer composition reaction.In general, said mylar makes through the polycondensation reaction of sour composition such as polyvalent carboxylic acid or acid anhydrides and pure composition such as polyalcohol.The terminal hydroxyl of the mylar that generates and isocyanate prepolymer composition reaction are to obtain urethane-modified mylar.In this way, preferably add said isocyanate prepolymer composition and react in sour composition and pure composition reaction back.Perhaps, sour composition, pure composition and isocyanate prepolymer composition can react simultaneously.
The acid composition does not receive particular restriction, so long as polyvalent carboxylic acid or its acid anhydrides get final product.Its example comprises aromatic dicarboxylic acid and acid anhydrides thereof, like phthalic acid, M-phthalic acid, terephthalic acid (TPA) and phthalic acid; Aliphatic dicarboxylic acid and acid anhydrides thereof are like butanedioic acid, adipic acid, glutaric acid and decanedioic acid; With unsaturated dicarboxylic and acid anhydrides thereof, like maleic acid, fumaric acid and itaconic acid.They can use with two or more combinations.
The alcohol composition does not receive particular restriction, so long as polyalcohol gets final product.Its example comprises fatty alcohol, like ethylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, 1, ammediol, 1,4-butanediol and 1,4-cyclohexanediol; Aromatic diol; Alicyclic dihydroxylic alcohols; With the polyalcohol more than the ternary, like trimethylolpropane and pentaerythrite.They can use with two or more combinations.
Isocyanate prepolymer composition has plural NCO in its molecule.The aromatic isocyanate that in its molecule, has aromatic rings is absolutely necessary.The example of said aromatic isocyanate comprise XDI, toluene di-isocyanate(TDI), 4,4 '-'-diphenylmethane diisocyanate, naphthalene diisocyanate and inferior biphenyl diisocyanate.They can use with two or more combinations.And; Under the situation of not damaging performance of the present invention; Can use aliphatic diisocyanate such as trimethyl hexamethylene diisocyanate, hexamethylene diisocyanate or trimethylene diisocyanate with aromatic isocyanate, or alicyclic diisocyanate such as cyclohexane diisocyanate.
The total amount of the aromatic component that contains in sour composition, pure composition and the isocyanate prepolymer composition as stated, is the 5mol% to 50mol% of the total amount of said sour composition, pure composition and isocyanate prepolymer composition.Make these material reactions to obtain urethane-modified mylar through conventional method.
The blocked isocyanate that the present invention uses is to use the compound of end-capping reagent with polyfunctional isocyanate's terminal isocyanate group end-blocking.The end-capping reagent decomposes is to form NCO.The hydroxyl reaction of NCO and urethane-modified mylar is with crosslinked urethane-modified mylar.
The example of end-capping reagent comprises the compound with activity hydroxy, like alcohol, phenol, acid amides, oxime and active methylene group.
Can use any isocyanates such as trimethylene diisocyanate, hexamethylene diisocyanate (HDI) or methyl diphenylene diisocyanate (MDI) as the polyfunctional isocyanate.Especially, preferably add the mould assembly isocyanates by general formula (I) expression and by what isocyanate-monomer and polyol formed.
[Chemical formula 1]
Figure GPA00001204447700071
(wherein, R1~R3 represents the group of getting rid of NCO from aliphat, alicyclic or aromatic diisocyanate separately; And the group of hydroxyl is got rid of in the R4 representative from polyol)
Polyol is the compound that in its molecule, has two above hydroxyls.Its example comprises glycerine, trimethylolethane, trimethylolpropane, 1,4-butanediol, neopentyl glycol and 1,6-hexylene glycol.The example of vulcabond comprises trimethylene diisocyanate, hexamethylene diisocyanate and '-diphenylmethane diisocyanate.
Can use any metal such as copper, gold, silver, platinum and nickel and alloy thereof as conductive metal powder used among the present invention.The preferred silver powder that uses with superior electrical conductivity.The example of its shape comprises but is not limited to especially: spherical, flakey and graininess.
Can suitably select the content of conductive metal powder according to desired properties.The increase of conductive metal powder content causes the raising of conductivity.Too high conductive metal powder content causes the adhesion strength (cohesive strength) between resinous principle and conductive metal powder to reduce, and therefore in conduction is stuck with paste, forming the space after the coating, influences impressionability and reduces adhesiveness.And, also reduced conductivity.Therefore, conductive metal powder content is preferably below 95% of solid state component that conduction is stuck with paste.
In addition, the increase of conductive metal powder content makes conduction stick with paste hardening, has therefore reduced flexibility.In order to average out between the conductivity of sticking with paste in conduction and the flexibility, conductive metal powder content is preferably 50% to 85% of solid state component total amount that conduction sticks with paste.
Preferred compositions use particle mean size be metal dust A and the particle mean size of 0.5 μ m to 20 μ m as the metal dust B below the 100nm as conductive metal powder, and metal dust A is 99.5: 0.5~70: 30 to the weight content ratio of metal dust B.When the content that increases metal dust A up to metal dust A to the content of metal dust B when surpassing 99.5: 0.5, combined effect is lowered, thereby reduces conductivity.When the content that increases metal dust B up to content when surpassing 70: 30, the increase of the amount of metal dust B has improved cost, is not preferred.Metal dust A compared more preferably 99: 1 to 90: 10 the content of metal dust B.
Metal dust A preferably has the particle mean size of 0.5 μ m~20 μ m.0.5 the particle mean size below the μ m causes conductivity to reduce.The particle mean size that surpasses 20 μ m makes fine printing processing become difficult.Based on same reason, the powder that preferred use does not have great maximum particle size.Preferred maximum particle size is the powder of 20 μ m~50 μ m.It should be noted that the maximum gauge of said size definition, and its mean value is defined as particle mean size for each particle.For example, use scanning electron microscopy (SEM) to measure.
Except using one type powder, also can make up to use and multiplely have different particle mean sizes and difform powder as metal dust A.For example, the flatness further improved after conductivity and the coating is used in the combination of flakey silver powder and spherical silver powder.
Metal dust B is the metal dust with the particle mean size below the 100nm.In the powder of nanoscale, particle aggegation mutually.Term " particle mean size " is used to show the particle mean size of initiating particle.And the powder of this nanoscale has big specific area, therefore has high surface.In order to protect the surface and to suppress the generation of secondary aggegation, the powder that preferably uses powder particle surface wherein to be covered by organic substance.Organic example comprises polybasic carboxylic acid and polyacrylic acid.
For example, can make particle mean size as follows is the metal dust B below the 100nm: in the mixed solvent of silver nitrate is water-soluble and lower alcohol.Use more than the ammoniacal liquor adjustment pH to 11.To wherein adding by being dissolved in the formed solution of same mixture solvent, thereby separate out silver particles as the L-ascorbic acid of reducing agent with as the polyacrylic acid of dispersant.When using dispersant to suppress the secondary aggegation, the silver particles of separating out is filtered, washed and drying.Can be through changing the particle mean size that pH, temperature, concentration of material, mixed method etc. change silver particles.
Especially, in silver particles, in reactions step, use dispersant to generate the silver particles that the surface is covered by dispersant through the above-mentioned steps preparation.In the formation stage, the surface of silver particles is covered by dispersant, therefore makes silver particles not too responsive to air.And, be difficult for taking place the secondary aggegation of silver particles.Even the generation aggegation because the existence of dispersant, for example can be used organic solvent and destroys agglutination particle at an easy rate.And in resin, silver particles has satisfied dispersiveness.
Said conductive metal powder, said urethane-modified mylar and said blocked isocyanate are mixed to form the conduction paste.Before use, said urethane-modified mylar and said blocked isocyanate are dissolved in the solvent.Can use any solvent that can dissolve said resin.Its example comprises ester class, ethers, ketone, ether-ether class, alcohols, hydro carbons and amine solvent.When using conduction to stick with paste through silk screen printing, the high boiling solvent that preferably has satisfied printing.Specifically, special preference card must alcohol acetic ester and acetate of butyl carbitol.
In order to improve the printing processing characteristics, can, silver of the present invention add additive in sticking with paste, like thickener and levelling agent.And, under the situation of not damaging performance of the present invention, can add the inorganic filler of for example forming by carbon and silicon dioxide.These materials use for example ball mill, three-roll mill, the mixing of revolution stirring/deaeration machine and disperse, and stick with paste to form uniform conductive.
Electromagnetic shielding film of the present invention comprises by above-mentioned conduction sticks with paste the layer of on base material, processing.After being coated on above-mentioned conduction paste on the base material, the dry solvent of also removing, conduction is stuck with paste and is produced curing, thereby obtains electromagnetic shielding film.Can use polyester film or polyimide film as base material.Consider flexibility, preferred polyimide film.Fig. 1 is the cross sectional representation of exemplary electrical magnetic shield film.Said electromagnetic shielding film comprises leads electric paste layer 2 on the base material 1.To lead electric paste layer in order protecting, can diaphragm 8 to be set on the electric paste layer 2 leading.During use, remove diaphragm 8.
One or two surface that said electromagnetic shielding film is laminated to flexible printing wiring board is to provide electromagnetic shielding flexible printing wiring board of the present invention.Fig. 2 is the cross sectional representation of example electromagnetic shielded flexible printed wiring board.Flexible printing wiring board 7 comprises the circuit that is made up of the Copper Foil on the base material 45, and said circuit lining cap rock covers.Cover layer is made up of covering layer film 6a that constitutes like polyimides and cover layer adhesive 6b.Electromagnetic shielding film 3 is attached to the cover layer side of flexible printing wiring board.Perhaps, can lead electric paste layer with formation with conducting electricity to stick with paste directly be coated on the flexible printing wiring board.
The coating thickness that conduction is stuck with paste does not receive particular restriction, and preferred in the scope of 10 μ m~50 μ m.The electromagnetic shielding characteristic that thickness below the 10 μ m can not obtain to expect.The above thickness of 50 μ m has damaged the flexibility of screen, has therefore reduced resistance to bend(ing).
The example of the coating process that conduction is stuck with paste comprises silk screen printing, intaglio printing, offset printing and use distributor.Consider tractability and the thickness and the productivity ratio of circuit, most preferably use silk screen printing.
Perhaps, can conduction of the present invention be stuck with paste and directly be coated on the flexible printing wiring board and solidify to form electro-magnetic screen layer.Also the electromagnetic shielding flexible printing wiring board that comprises the layer that is pasted by the present invention's conduction is provided through said method.Likewise, with conducting electricity to stick with paste the shielding casing that comprises the layer that is pasted by the present invention's conduction separately is provided on the shell that is applied to electronic device such as PC and mobile phone.
To preferred forms of the present invention be described through embodiment below.Scope of the present invention is not limited to these embodiment.
Embodiment
(embodiment 1~3 and comparative example 1~3)
(preparation that conduction is stuck with paste)
Prepared urethane-modified polyester through the reaction formation of the sour composition that is shown in Table 1, pure composition and isocyanate prepolymer composition.Specifically, the mixed solvent with the sour composition that is shown in table 1 and pure composition and acetate of butyl carbitol and BC adds in the four neck flasks.Under nitrogen current, mixture is heated to 60 ℃.Then to wherein adding isocyanate compound, and be heated to 80 ℃ and kept 5 hours, with the polyester of synthesis of carbamates modification.
To be the flakey silver powder of 3.0 μ m and spherical silver powder that particle mean size is 25nm as conductive metal powder and blocked isocyanate mixes with the urethane-modified mylar that makes with formation conducts electricity paste with particle mean size.Urethane-modified polyester is set to the equivalent mol ratio to the mixing ratio of blocked isocyanate.The mixing ratio of conductive metal powder is set to ratio described below.
The mixing ratio of flakey silver powder (weight)=(weight of the weight+blocked isocyanate of urethane-modified mylar) * 2.1
The mixing ratio of spherical silver powder (weight)=(weight of the weight+blocked isocyanate of urethane-modified mylar) * 0.233
(sample that manufacturing is used to estimate)
Made the copper laminate (two-layer CCL) of adhesive-free layer, wherein copper foil layer is laminated on the polyimide film.(subtractive method) optionally corrodes the Copper Foil part through subraction, forms the pattern of live width 50 μ m.Stick the flexible printing wiring board that covering layer film is used to estimate with manufacturing in the above.To conduct electricity through silk screen print method and to stick with paste on the cover layer side be coated on flexible printing wiring board and hot curing in baker.The crooked sample of estimating that is used to slide is pasted over the coating solder resist in conduction, and hot curing in baker.
(the evaluation that conduction is stuck with paste: specific insulation)
Sample is cut into the wide sheet of 5mm.Carry out resistance value through four probe method and measure (the distance between probe: 100mm).Use surface roughness tester to measure said silver and stick with paste the thickness of cured film.Volume calculated resistivity then.
(the evaluation that conduction is stuck with paste: adhesion strength)
Make twice in said sample through being set at the reflow soldering of 260 ℃ of maximum temperatures.Between said silver-colored cured film of sticking with paste and said covering layer film, form recess then.The cured film that said silver is stuck with paste is crooked with 180 ℃ direction, and stretch with 50mm/ minute speed and to measure adhesion strength.
(the evaluation that conduction is stuck with paste: the slip bend test)
Same as described above, make twice in said sample through being set at the reflow soldering of 260 ℃ of maximum temperatures.Then under the condition of stroke 100mm, 15 seconds/cycle and slip bending radius 1.0mm, to the sample crooked test that slides.Slip number of bends to line resistance improved 20% o'clock is estimated.The result is shown in Table 1.In assessment item, satisfied scope is following: adhesion strength is more than the 0.8N/cm, and the slip number of bends is more than 70000 times, and specific insulation is 90 * 10 -6Below the Ω cm.
Figure GPA00001204447700131
In comparative example 1, the total amount of the aromatic component that contains in sour composition, pure composition and the isocyanate prepolymer composition is less than the 5mol% of said sour composition, pure composition and isocyanate prepolymer composition total amount, and the adhesion strength after the reflow process is low, and poor heat resistance.Likewise, do not contain in the comparative example 2 of aromatic component at isocyanate prepolymer composition, the adhesion strength after the reflow process is low, and poor heat resistance.Total amount at aromatic component surpasses in the comparative example 3 of 50mol%, though adhesion strength is good, the bending property of sliding is poor.
(comparative example 4 to 8)
The different urethane-modified mylar different of the degree of polymerization have been prepared with hydroxyl value.Use resins among the embodiment 1~3 conduction stick with paste.Adhesion strength after the reflow process, slip bending property and specific insulation are estimated.The result is shown in Table 2.
[table 2]
Figure GPA00001204447700141
Urethane-modified mylar has correlation between adhesion strength after the reflow process and hydroxyl value.Higher hydroxyl value causes adhesion strength to be improved.In the embodiment 4 of hydroxyl value less than 5mg KOH/g, adhesion strength is 0.8N/cm, and this is lower slightly.Surpass among the embodiment 8 of 60mgKOH/g in hydroxyl value, flexible poor, and the slip number of bends is lower slightly.
(embodiment 9 to 13)
As shown in table 3, prepared polyfunctional blocked polyisocyanate compound with different number-average molecular weights.Said polyfunctional blocked polyisocyanate compound is to use the compound of the end-capped that adds the mould assembly isocyanates that end-capping reagent will form by isocyanate-monomer and polyol.As among the embodiment 1~3, urethane-modified mylar described in the embodiment 1 and the combination of polyfunctional blocked polyisocyanate compound to be used as curing agent, the preparation conduction is stuck with paste.Adhesion strength after the reflow process, slip bending property and specific insulation are estimated.
[table 3]
Figure GPA00001204447700151
In each sample, adhesion strength, slip bending property and resistivity all satisfy desired characteristic.The number-average molecular weight of polyfunctional blocked polyisocyanate compound less than 500 embodiment 9 in, the slip number of bends is 80000 times, this is lower slightly.Surpass among 3000 the embodiment 13 in number-average molecular weight, specific insulation is slightly high.
(embodiment 14 to 18)
Use used urethane-modified mylar and polyfunctional blocked polyisocyanate compound among the embodiment 1.Except through the ratio of mixing ratio that changes both, as among the embodiment 1~3, prepared conduction and stuck with paste with change NCO/OH.Adhesion strength after the reflow process, slip bending property and specific insulation are estimated.The result is shown in Table 4.The ratio of NCO/OH less than 0.8 embodiment 14 in, specific insulation is slightly high.This is because the low ratio of NCO/OH causes crosslink density to reduce by inference.Ratio at NCO/OH surpasses among 3.0 the embodiment 18, and the adhesion strength after the reflow process is lower slightly.This is because the NCO/OH height ratio causes excessive curing agent residual by inference, thereby causes thermal endurance to descend.
[table 4]
Figure GPA00001204447700161
(embodiment 19 to 23)
Prepared particle mean size and be the metal dust A of 4.8 μ m and metal dust B that particle mean size is 30nm as conductive metal powder.Except the content ratio that changes metal dust A and metal dust B, as among the embodiment 1~3, prepared conduction and stuck with paste.Adhesion strength after the reflow process, slip bending property and specific insulation are estimated.In this case, the total weight of metal dust A and metal dust B is set to 2.333 times of total weight of urethane-modified mylar and blocked isocyanate.
The result is shown in Table 5.Metal dust A to the content of metal dust B than in less than 99.5: 0.5 embodiment 19, specific insulation is slightly high.At metal dust A the content of metal dust B is surpassed among 70: 30 the embodiment 23, do not improve the special result of character.The metal dust price that particle mean size is about nanoscale is very high.Consider character and cost that conduction is stuck with paste, metal dust A compares preferably in 99.5: 0.5 to 70: 30 scope the content of metal dust B.
[table 5]
Figure GPA00001204447700171
Prepared particle mean size and be the metal dust A of 4.8 μ m and metal dust B that particle mean size is 30nm as conductive metal powder.Metal dust A was fixed as 90: 10 the content ratio of metal dust B and the metal dust that difference contains ratio is defined as the total amount of metal dust A and metal dust B, prepare conduction and stick with paste.Adhesion strength after the reflow process, slip bending property and specific insulation are estimated.
The result shows that in containing under the situation of ratio less than 50 weight % of metal dust, specific insulation is slightly high.The ratio that contains at metal dust surpasses under the situation of 85 weight %, and the slip bending property is lower slightly.This is to cause flexible decline because too high metal dust contains ratio by inference.
Should be appreciated that execution mode disclosed by the invention and embodiment are illustrative, and all unrestricted in every respect.Scope of the present invention is limited the scope of claim, rather than is limited above-mentioned explanation, and is intended to be included in this claim scope or is equal to any modification of meaning with the scope of claim.
Industrial applicibility
The present invention relates to conduct electricity electromagnetic shielding film and the electromagnetic shielding flexible printing wiring board of sticking with paste and using this conduction paste.Especially, the present invention can compatibly be used for the flexible printing wiring board that requirement has resistance to bend(ing).
Symbol description:
1 base material
2 lead electric paste layer
3 electromagnetic shielding films
4 base materials
5 Copper Foils
The 6a covering layer film
6b cover layer adhesive
7 flexible printing wiring boards
8 diaphragms
Patent documentation
Patent documentation 1: the spy opens flat 1-159906 communique
Patent documentation 2: the spy opens flat 9-306240 communique
Patent documentation 3: the spy opens the 2005-294254 communique

Claims (7)

1. a conduction is stuck with paste, and it comprises:
Conductive metal powder, urethane-modified mylar and blocked isocyanate,
Wherein said urethane-modified mylar makes through the isocyanate prepolymer composition reaction that makes sour composition, pure composition and contain aromatic isocyanate, and
The total amount of the aromatic component that in said sour composition, pure composition and isocyanate prepolymer composition, contains is 5 moles of % to 50 mole of % of the total amount of said sour composition, pure composition and isocyanate prepolymer composition.
2. conduction as claimed in claim 1 is stuck with paste, and the hydroxyl value of wherein said urethane-modified mylar is 5mg KOH/g to 60mg KOH/g.
3. conduction as claimed in claim 1 is stuck with paste; Wherein said blocked isocyanate has 500~3000 number-average molecular weight; And be polyfunctional blocked polyisocyanates compound; Wherein use end-capping reagent will add the end-capped of mould assembly isocyanates, the said mould assembly isocyanates that adds is formed by isocyanate-monomer and polyol.
4. conduction as claimed in claim 1 is stuck with paste; Wherein, Convert with the NCO (NCO) of the said blocked isocyanate mol ratio (NCO/OH) to the hydroxyl (OH) of said urethane-modified mylar, said blocked isocyanate is 0.8~3.0 to the mixing ratio of said urethane-modified mylar.
5. conduction as claimed in claim 1 is stuck with paste; Wherein said conductive metal powder is that metal dust A and the particle mean size of 0.5 μ m to 20 μ m is that metal dust B below the 100nm forms by particle mean size; And wherein said metal dust A is 99.5: 0.5 to 70: 30 to the weight content ratio of said metal dust B, and the content ratio of the solid state component during the said conduction of said conductive metal powder foot couple is stuck with paste is 50 weight % to 85 weight %.
6. electromagnetic shielding film, it is included in the layer on the base material, and said layer is pasted by each conduction in the claim 1 to 5.
7. electromagnetic shielding flexible printing wiring board, it comprises the layer that is pasted by each conduction in the claim 1 to 5.
CN2009801051008A 2008-11-14 2009-10-13 Conductive paste, electromagnetic wave-shielding film using same, and electromagnetic wave-shielding flexible printed wiring board Expired - Fee Related CN101952902B (en)

Applications Claiming Priority (3)

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JP2008-291596 2008-11-14
JP2008291596A JP5446222B2 (en) 2008-11-14 2008-11-14 Conductive paste, electromagnetic shielding film using the same, and electromagnetic shielding flexible printed wiring board
PCT/JP2009/067715 WO2010055742A1 (en) 2008-11-14 2009-10-13 Conductive paste, electromagnetic wave-shielding film using same, and electromagnetic wave-shielding flexible printed wiring board

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