WO2008130955A1 - Corrosion-resistant anisotropic conductive compositions - Google Patents
Corrosion-resistant anisotropic conductive compositions Download PDFInfo
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- WO2008130955A1 WO2008130955A1 PCT/US2008/060405 US2008060405W WO2008130955A1 WO 2008130955 A1 WO2008130955 A1 WO 2008130955A1 US 2008060405 W US2008060405 W US 2008060405W WO 2008130955 A1 WO2008130955 A1 WO 2008130955A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/20—Conductive material dispersed in non-conductive organic material
- H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
Definitions
- the present invention relates to corrosion-resistant anisotropic conductive compositions and electronic devices made using the corrosion-resistant anisotropic conductive compositions Specifically, the present invention relates to corrosion-resistant anisotropic conductive compositions useful in electronic devices that contain non-noble metal substrates
- Anisotropic conductive compositions are used to interconnect various electronic devices, including chip-on-glass assembly, flip chip assembly and contactless smart-card module assembly
- Anisotropic conductive compositions are capable of bonding substrates together such that conductivity is exhibited in one direction and electric current is conducted only between the sites intended to be connected
- anisotropic conductive compositions provides cost savings due to their simple and flexible processing capabilities, and environmental benefits relating to the reduction in use of hazardous materials and precious metals
- RFID radio-frequency identification
- PET polyethylene terephtalate
- the typical circuit metallization for RFID application can be printed in silver or gold ink, stamped or etched aluminum, or etched or vapor deposited copper, and the like, as compared to conventional electroless gold plated circuitry
- the substrates that were once gold plated are replaced with aluminum or etched aluminum substrates
- One challenge with aluminum substrate is that it readily oxidizes on exposure to atmospheric moisture to create a thin insulting layer of aluminum oxide
- the anisotropic conductive fillers initially penetrate though the oxide layer to make good electrical contact with the aluminum during the bonding process, the z-axis electrical conductivity is not reliably consistent for the assembly.
- the assembly is subjected to high temperature and humidity conditions (85°C/85%RH)
- the electrical contact between the chip and circuitry is lost over time
- the corrosion at the interface spreads into the interior of the adhesive and adhesion is lost over time
- the present invention discloses an anisotropic conductive composition that provides stable and reliable z-axis electric conductivity on electronic assemblies that utilize non-noble metal substrates It is the object of the invention to provide an anisotropic conductive composition which imparts a consistent z-axis electrical conductivity and maintains anisotropic conduction and adhesion under 85°C/85%RH condition on non-noble metal substrates
- the invention provides an anisotropic conductive composition
- a polymeric resin comprising a curing agent, conductive fillers, and a corrosion inhibitor and/or an oxygen scavenger
- the composition imparts improved electrical stability and anti-corrosion durability under 85°C/85%RH condition while maintaining good adhesion for electronic assemblies with non-noble metal substrates
- the anisotropic conductive composition further comprises diluents, flow additives, rheology modifiers, inert fillers, defoamers, colorants and adhesion promoters
- Another aspect of the invention is directed to a method of making or forming an anisotropic conductive film by coating the anisotropic conductive composition onto a supporting liner and drying the composition to a non-tacky state to be activated at a later time
- Yet in another embodiment of the invention provides articles manufactured using the anisotropic conductive composition on non-noble metal substrates Encompassed include smart cards, RFID, chip-on-flex (COF), chip-on-board (COB), flip chip and the like Still another aspect is directed to a process of sealing and/or forming electronic devices and electronic components These processes comprise using the anisotropic conductive composition of the invention on electronic devices with non-noble metal substrates
- ble metal herein is used to refer to precious metals that are resistant to corrosion or oxidation and includes gold, silver, tantalum, platinum, palladium and rhodium
- non-noble metal herein is used to refer to metal that oxidizes or corrodes relatively easily and includes aluminum, copper, iron, nickel, lead, zinc, tin, bismuth and its alloys.
- bare substrate herein is used to refer to substrate that has not been treated with any chemicals (e g organic sotder preservative) or physical treatments to remove oxide layers
- non-noble metal substrate herein is used to refer to substrates that are made with non-noble metals
- Various methods of depositing the non-noble metals onto PET and/or paper include, stamping, etching, vapor deposition
- Exemplary non-noble meta! substrate include stamped aluminum, etched aluminum, etched copper, vapor deposited copper, and the like.
- corrosion inhibitor herein is defined as a chemical compound that has a lone pair of electrons, such as nitrogen-, sulfur-, and oxygen-containing compounds, that binds with metai and impedes the reactivity of the metal at the eiectrochemicai anode
- oxygen scavenger herein is defined as a chemical compound that reacts with oxygen to prevent metal from reacting at the electrochemical cell cathode.
- stable conductivity herein is defined as z-axis electrical resistance that increases less than four times the initial z-axis electrical resistance under 85 0 C and 85% relative humidity (85°C/85%RH) condition
- anisotropic conductive compositions provides consistent initial z-axis electrical conductivity and maintains stable z-axis electrical conductivity under 85°C/85%RH on non-noble meta! substrates
- the compositions of this invention also provide good screen p ⁇ ntabihty, good work-life, excellent connection and adhesion stability to non-noble metai substrates
- the anisotropic conductive composition comprises a polymeric resin, curing agent, conductive fillers and a corrosion inhibitor and/or an oxygen scavenger
- poiymeric resins include any class of conjugated double bond polvmers currently used throughout the industry, such as polyanihne, polypyrrole polythiophene polyfuran, poiyphenyiene and mixtures thereof
- exemplary polymeric resins include vinyl acrylic phenolic, phenoxy, epoxy, maleimide, polyesters, polyimide, polyurethanes polyolefi ⁇ s, polysulfide, ⁇ it ⁇ le, silicone and mixtures thereof
- the polyme ⁇ c resin is utilized in the range of about 40 to about 90 weight percent of the total composition and preferably from about 50 to about 80 weight percent of the total composition
- Non-limiting examples of the curing agents include amines, anhydrides, anhydride adducts, phenol compounds, dicyanediamine blocked imidazoles, and imidazole adducts
- Particularly useful curing agents include 2-methyl ⁇ m ⁇ dazole, 2-pheny! ⁇ m ⁇ dazole, 2-phenyl-4-methyl ⁇ m ⁇ dazo!e 2-ethyl-4- methylimidazole 2-undecyl ⁇ m ⁇ dazole, 1 -benzy]-2-methyl ⁇ m ⁇ dazole, i-cyanoethyi-2-methyl ⁇ m ⁇ dazole, 1 -cyanoethy!-2-ethyl-4-r ⁇ ethyl ⁇ rmdazole and the like
- Curing agent is present in the anisotropic conductive composition from about 5 to 40 weight parts per 100 weight parts of epoxy resins
- the conductive fillers are metallic or metal-coated polymer particles
- a non-limiting example of conductive fillers include silver, copper, gold palladium, platinum, nickel, gold or silver-coated nickel, carbon black, carbon fiber, graphite, aluminum, indium tin oxide, silver coated copper, silver coated aluminum, metallic coated glass spheres metallic coated filler, metallic coated polymers silver coated fiber, silver coated spheres, and antimony doped tin oxide and mixtures thereof
- the volume fraction of particles is well below the percolation threshold usually between 5 and 10%, and the particles are usually in the range of about 3 to 10 ⁇ m in diameter Due to the low volume fraction, there are no continuous conductive paths among the particles in the x-y plane The composition therefore conducts electricity only in the z direction
- the mean particle size of the conductive filler varies depending on the electrode s width and the spacing between the adjacent electrodes in general, the conductive filler may have a mean particle size of from about 0 5 ⁇ m to about 500Lim, preferably from about 2 ⁇ m to about 40 ⁇ m
- the total amount of the conductive filler varies depending on the area of the electrodes and the mean particle size of the conductive filler In general the conductive fillers make up about 5 wt% to about 60 wt%, preferably about 10 wt% to about 40 wt% of the total composition A satisfactory connection may be achieved with a few (for example about 2 to about 10) particles of conductive filler present per electrode For even lower electrical resistance, more particles of conductive filler may be present per electrode
- Corrosion inhibitors include, among others, aromatic triazoles, imidazoles, thiazoles, and phosphorous-based compound
- Exemplary corrosion inhibitors are 1 , 10-phenath ⁇ od ⁇ ne, phenothiazme, be ⁇ zot ⁇ azole tolyltriazole, carboxybenzotriazole, sodium tolyltriazole, benzimidazole, mercaptobenzothiazoie, dicyandiamide, 3- ⁇ soprolyam ⁇ no-i -butyne, propargyl quinolinium bromide, 3-benzylam ⁇ no-1-butyne, dipropargl ether, dipropargyi thioether, propargyl caproate, dianimoheptane, phe ⁇ athrolme, amine, diamine, t ⁇ amine, hexamethyleneimide,
- diluents include both reactive and non-reactive diluents, such as glycidyl ethers (for examples, 1 ,4-butaned ⁇ ol diglycidyl ether), vinyl ethers (for example, ethylene vinyl ether), vinyl esters, (for example, ethylene vinyl ester), acrylates (for example, methyl methacrylate) and butyl carbitol
- glycidyl ethers for examples, 1 ,4-butaned ⁇ ol diglycidyl ether
- vinyl ethers for example, ethylene vinyl ether
- vinyl esters for example, ethylene vinyl ester
- acrylates for example, methyl methacrylate
- Non-limiting examples of and flow additives and rheology modifiers include fumed silica
- nano-clay Preferred inert fillers include siiica, alumina and calcium carbonate.
- Exemplary defoamers include foam destroying polysiloxanes, polyacrylates and polyether modified methylalkyl polysiloxane copolymers
- Exemplary adhesion promoters are silanes and polyvinyl bulyrol The optional additives may be added up to about 40 weight percent of the total composition
- the anisotropic conductive composition may be formed into an adhesive or an adhesiv e film As an adhesive, the composition is placed in between the chip and the non-noble metal substrate, then cured via heat and pressure In one embodiment, the anisotropic conductive composition has a cure speed of less than about 30 seconds at about 170°C T or about less than 10 seconds at about 18O 0 C with about 3 N.
- One skilled in the art may adjust the temperature and pressure according to the needs of the assembly, without undue experimentation
- An adhesive film may be obtained by coating the anisotropic conductive composition onto a support liner and drying a composition until non-tacky to be activated at a later time. Activation may be performed by thermo-compression mechanism.
- the anisotropic conductive composition of the present invention has consistent initial ⁇ -axis electrical conductivity and stable anisotropic conduction on non-noble metal substrates
- the composition also provides good screen p ⁇ ntability, good work-life, excellent connection and adhesion stability to non-noble metal substrates.
- the anisotropic conductive composition of the present invention consistently imparts reliable initial contact resistance in assembly with no ⁇ -nobie metal substrates
- the anisotropic conductive composition of the present invention maintains stable z-axis electrical conductivity under 85°C/85%RH for at least 42 days (1000 hours) in assembly with non-noble metal substrates
- the anisotropic conductive composition of the present invention can maintain good adhesion with a non- noble metal substrate even under 85°C/85%RH condition.
- the anisotropic conductive composition of the present invention maintains work-life greater than eight hours at room temperature Assemblies made with room-temperature aged anisotropic conductive compositions of the invention resulted in excellent initial connection and adhesion stability to non-noble metal substrates
- the anisotropic conductive composition may be used to assemble chip-on-glass, flip chips, contactiess smart-card module, COF, COB, and RFiD
- the anisotropic conductive composition may be placed in between a semiconductor component and a non-noble metai substrate, activate the composition by means of thermo-compression, and allowing the chip and the substrate to adhere.
- Anisotropic conductive compositions of listed in Table 1 were prepared as follows (1 ) resins, rheoiogy modifier, adhesion promoter and corrosion inhibitor (Formulation 1 ) were mixed at a high speed with SpeedMixer (FlackTek) until homogenous, (2) curing agent was added and mixed at a medium speed, until the mixture was homogenous; (3) conductive fillers were added and mixed at a medium speed, until the mixture was homogenous, and (4) the mixture was degassed for five minutes in a vacuum chamber with >28 in Hg
- Formulations 2-4 had the components as Formulation 1 , except a different corrosion inhibitor/oxygen scavengers were used, as indicated in Table 3.
- the DSS indicated that the formulations with corrosion inhibitor and/or oxygen inhibitors provided overall improved long term shear strength even under 85 C C/85%RH for 7 days. Furthermore, the package assembled with corrosion inhibitor and/or oxygen inhibitors had more consistent die shear strength than Comparative A Example 4 Work-life and Screen Printing Evaluation
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Abstract
The invention provides an anisotropic conductive composition comprising a polymeric resin, a curing agent, conductive fillers, and a corrosion inhibitor and/or an oxygen scavenger.
Description
CORROSION-RESISTANT ANISOTROPIC CONDUCTIVE COMPOSITIONS
The present application claims the benefit to U S Provisional Application No 60/912,223 filed April 17, 2007, which is incorporated by reference herein in its entirety
FIELD OF INVENTION
The present invention relates to corrosion-resistant anisotropic conductive compositions and electronic devices made using the corrosion-resistant anisotropic conductive compositions Specifically, the present invention relates to corrosion-resistant anisotropic conductive compositions useful in electronic devices that contain non-noble metal substrates
BACKGROUND OF INVENTION
Anisotropic conductive compositions are used to interconnect various electronic devices, including chip-on-glass assembly, flip chip assembly and contactless smart-card module assembly Anisotropic conductive compositions are capable of bonding substrates together such that conductivity is exhibited in one direction and electric current is conducted only between the sites intended to be connected
The use of anisotropic conductive compositions provides cost savings due to their simple and flexible processing capabilities, and environmental benefits relating to the reduction in use of hazardous materials and precious metals
For high volume, low cost applications such as RFID (radio-frequency identification), trie use of low cost substrates like PET (polyethylene terephtalate) and paper are common The typical circuit metallization for RFID application can be printed in silver or gold ink, stamped or etched aluminum, or etched or vapor deposited copper, and the like, as compared to conventional electroless gold plated circuitry For high volume, low cost devices, the substrates that were once gold plated are replaced with aluminum or etched aluminum substrates One challenge with aluminum substrate is that it readily oxidizes on exposure to atmospheric moisture to create a thin insulting layer of aluminum oxide
Although the anisotropic conductive fillers initially penetrate though the oxide layer to make good electrical contact with the aluminum during the bonding process, the z-axis electrical conductivity is not reliably consistent for the assembly In addition, as the assembly is subjected to
high temperature and humidity conditions (85°C/85%RH), the electrical contact between the chip and circuitry is lost over time Furthermore, the corrosion at the interface spreads into the interior of the adhesive and adhesion is lost over time
There continues to be a need in the art for anisotropic conductive compositions that impart consistent initial z-axis electrical conductivity maintain anisotropic conduction under 85°C/85%RH conditions and provide good adhesion in electronic assemblies with non-noble metal substrate The current invention addresses this need
SUMMARY OF INVENTION
The present invention discloses an anisotropic conductive composition that provides stable and reliable z-axis electric conductivity on electronic assemblies that utilize non-noble metal substrates It is the object of the invention to provide an anisotropic conductive composition which imparts a consistent z-axis electrical conductivity and maintains anisotropic conduction and adhesion under 85°C/85%RH condition on non-noble metal substrates
The invention provides an anisotropic conductive composition comprising a polymeric resin, a curing agent, conductive fillers, and a corrosion inhibitor and/or an oxygen scavenger The composition imparts improved electrical stability and anti-corrosion durability under 85°C/85%RH condition while maintaining good adhesion for electronic assemblies with non-noble metal substrates In another embodiment of the invention, the anisotropic conductive composition further comprises diluents, flow additives, rheology modifiers, inert fillers, defoamers, colorants and adhesion promoters
Another aspect of the invention is directed to a method of making or forming an anisotropic conductive film by coating the anisotropic conductive composition onto a supporting liner and drying the composition to a non-tacky state to be activated at a later time
Yet in another embodiment of the invention provides articles manufactured using the anisotropic conductive composition on non-noble metal substrates Encompassed include smart cards, RFID, chip-on-flex (COF), chip-on-board (COB), flip chip and the like
Still another aspect is directed to a process of sealing and/or forming electronic devices and electronic components These processes comprise using the anisotropic conductive composition of the invention on electronic devices with non-noble metal substrates
DETAILED DESCRIPTION OF INVENTION
The term "noble metal" herein is used to refer to precious metals that are resistant to corrosion or oxidation and includes gold, silver, tantalum, platinum, palladium and rhodium
The term "non-noble metal" herein is used to refer to metal that oxidizes or corrodes relatively easily and includes aluminum, copper, iron, nickel, lead, zinc, tin, bismuth and its alloys.
The term "bare substrate" herein is used to refer to substrate that has not been treated with any chemicals (e g organic sotder preservative) or physical treatments to remove oxide layers
The term "non-noble metal substrate" herein is used to refer to substrates that are made with non-noble metals Various methods of depositing the non-noble metals onto PET and/or paper include, stamping, etching, vapor deposition Exemplary non-noble meta! substrate include stamped aluminum, etched aluminum, etched copper, vapor deposited copper, and the like.
The term "corrosion inhibitor" herein is defined as a chemical compound that has a lone pair of electrons, such as nitrogen-, sulfur-, and oxygen-containing compounds, that binds with metai and impedes the reactivity of the metal at the eiectrochemicai anode
The term "oxygen scavenger" herein is defined as a chemical compound that reacts with oxygen to prevent metal from reacting at the electrochemical cell cathode.
The term "stable conductivity" herein is defined as z-axis electrical resistance that increases less than four times the initial z-axis electrical resistance under 850C and 85% relative humidity (85°C/85%RH) condition
It has been discovered that the inclusion of corrosion inhibitors and/or oxygen scavengers in anisotropic conductive compositions provides consistent initial z-axis electrical conductivity and maintains stable z-axis electrical conductivity under 85°C/85%RH on non-noble meta! substrates The compositions of this invention also provide good screen pπntabihty, good work-life, excellent connection and adhesion stability to non-noble metai substrates,
The anisotropic conductive composition comprises a polymeric resin, curing agent, conductive fillers and a corrosion inhibitor and/or an oxygen scavenger
In one embodiment, poiymeric resins include any class of conjugated double bond polvmers currently used throughout the industry, such as polyanihne, polypyrrole polythiophene polyfuran, poiyphenyiene and mixtures thereof In anther embodiment, exemplary polymeric resins include vinyl acrylic phenolic, phenoxy, epoxy, maleimide, polyesters, polyimide, polyurethanes polyolefiπs, polysulfide, πitπle, silicone and mixtures thereof The polymeπc resin is utilized in the range of about 40 to about 90 weight percent of the total composition and preferably from about 50 to about 80 weight percent of the total composition
Non-limiting examples of the curing agents include amines, anhydrides, anhydride adducts, phenol compounds, dicyanediamine blocked imidazoles, and imidazole adducts Particularly useful curing agents include 2-methylιmιdazole, 2-pheny!ιmιdazole, 2-phenyl-4-methylιmιdazo!e 2-ethyl-4- methylimidazole 2-undecylιmιdazole, 1 -benzy]-2-methylιmιdazole, i-cyanoethyi-2-methylιmιdazole, 1 -cyanoethy!-2-ethyl-4-rπethylιrmdazole and the like
Curing agent is present in the anisotropic conductive composition from about 5 to 40 weight parts per 100 weight parts of epoxy resins
The conductive fillers are metallic or metal-coated polymer particles A non-limiting example of conductive fillers include silver, copper, gold palladium, platinum, nickel, gold or silver-coated nickel, carbon black, carbon fiber, graphite, aluminum, indium tin oxide, silver coated copper, silver coated aluminum, metallic coated glass spheres metallic coated filler, metallic coated polymers silver coated fiber, silver coated spheres, and antimony doped tin oxide and mixtures thereof
The volume fraction of particles is well below the percolation threshold usually between 5 and 10%, and the particles are usually in the range of about 3 to 10 μm in diameter Due to the low volume fraction, there are no continuous conductive paths among the particles in the x-y plane The composition therefore conducts electricity only in the z direction
The mean particle size of the conductive filler varies depending on the electrode s width and the spacing between the adjacent electrodes in general, the conductive filler may have a mean particle size of from about 0 5 μm to about 500Lim, preferably from about 2μm to about 40 μm
The total amount of the conductive filler varies depending on the area of the electrodes and the mean particle size of the conductive filler In general the conductive fillers make up about 5 wt% to about 60 wt%, preferably about 10 wt% to about 40 wt% of the total composition A satisfactory connection may be achieved with a few (for example about 2 to about 10) particles of conductive filler present per electrode For even lower electrical resistance, more particles of conductive filler may be present per electrode
As will be recognized, some oxygen scavengers have corrosion inhibition capability, and some corrosion inhibitors have oxygen scavenger ability Corrosion inhibitors include, among others, aromatic triazoles, imidazoles, thiazoles, and phosphorous-based compound Exemplary corrosion inhibitors are 1 , 10-phenathιodιne, phenothiazme, beπzotπazole tolyltriazole, carboxybenzotriazole, sodium tolyltriazole, benzimidazole, mercaptobenzothiazoie, dicyandiamide, 3-ιsoprolyamιno-i -butyne, propargyl quinolinium bromide, 3-benzylamιno-1-butyne, dipropargl ether, dipropargyi thioether, propargyl caproate, dianimoheptane, pheπathrolme, amine, diamine, tπamine, hexamethyleneimide, decamethylenejmide, hexamethylene- iminebenzoate, hexamethyleneim πe- 3,5-dιnιtrobenzoate, hexamethylen-etetramin, d-oximino-b-vinyl quinuclidine, aniline, 6-N-ethyl purine, i-ethylamino-Σ-octadecylimidazohne, morpholine, ethanolamme, aminopheπol, 2 hydroxyquinolme, 6-hydroxyquιnolιne, 8-hydraxyquιnolιne, pyridine and its derivatives quinohne and its derivatives, acridine, imidazole and its derivatives, toluidine, mercaptan, thiophenol and its denvates, sulfide, sulfoxide, thiophosphate, thiourea and pipeπdine, 3-thιazole benzothiazoles 2,4- dimethyithiazol 2-(tπmethylsιlιyl)thιazofe, 2-(dιmethylamιno)thιazole, thiazolium salt, and dinonynaphthalene sulfonate/carboxylate/amiπe adduct Particularly preferred corrosion inhibitors are tolyltriazole, benzotriazole, carboxybenzotriazole, soldium toyitriazole (available from PMC Specialties, lnc , Cincinnati, Ohio under the trade name COBRATEC®) and mono- and diphosphate ester, polyhydroxy amides, phosphonoxy ester and phosphate salts (available from ADD APT Chemicals BV, Netherland, under the Anticor series) Exemplary oxygen scavengers are hydroquinone, carbohydrazide, tπhydroxybenzene, aminophenol, hydrazine, pyrogallol, carbohydrazone, polyethyleπeamme, cyclohexanedione, hydroxylamme, methoxypropylamine cyclohexylamine, diethylethanolamme, hydroxyalkylhydroxylamine, tetrasubstituted phenylenediammes, morphohnohexose reduction, keto-gluconates, amine bisulfites, lactone
derivatives, phenol derivatives, and substituted quinolines Corrosion inhibitor and/or oxygen scavenger will be present in the anisotropic conductive composition in an amount up to 10 weight percent, but not 0%
Optionally other additives, such as diluents, flow additives, rheology modifiers, inert fillers, defoamers, colorants and adhesion promoters may be added to the anisotropic conductive composition Exemplary diluents include both reactive and non-reactive diluents, such as glycidyl ethers (for examples, 1 ,4-butanedιol diglycidyl ether), vinyl ethers (for example, ethylene vinyl ether), vinyl esters, (for example, ethylene vinyl ester), acrylates (for example, methyl methacrylate) and butyl carbitol Non-limiting examples of and flow additives and rheology modifiers include fumed silica, nano-clay Preferred inert fillers include siiica, alumina and calcium carbonate. Exemplary defoamers include foam destroying polysiloxanes, polyacrylates and polyether modified methylalkyl polysiloxane copolymers Exemplary adhesion promoters are silanes and polyvinyl bulyrol The optional additives may be added up to about 40 weight percent of the total composition
The anisotropic conductive composition may be formed into an adhesive or an adhesiv e film As an adhesive, the composition is placed in between the chip and the non-noble metal substrate, then cured via heat and pressure In one embodiment, the anisotropic conductive composition has a cure speed of less than about 30 seconds at about 170°CT or about less than 10 seconds at about 18O0C with about 3 N. One skilled in the art may adjust the temperature and pressure according to the needs of the assembly, without undue experimentation
An adhesive film may be obtained by coating the anisotropic conductive composition onto a support liner and drying a composition until non-tacky to be activated at a later time. Activation may be performed by thermo-compression mechanism.
The anisotropic conductive composition of the present invention has consistent initial ∑-axis electrical conductivity and stable anisotropic conduction on non-noble metal substrates The composition also provides good screen pπntability, good work-life, excellent connection and adhesion stability to non-noble metal substrates. In one embodiment, the anisotropic conductive composition of the present invention consistently imparts reliable initial contact resistance in assembly with noπ-nobie metal substrates In another embodiment, the anisotropic conductive composition of the present invention maintains stable z-axis electrical conductivity under
85°C/85%RH for at least 42 days (1000 hours) in assembly with non-noble metal substrates The anisotropic conductive composition of the present invention can maintain good adhesion with a non- noble metal substrate even under 85°C/85%RH condition. In a further embodiment, the anisotropic conductive composition of the present invention maintains work-life greater than eight hours at room temperature Assemblies made with room-temperature aged anisotropic conductive compositions of the invention resulted in excellent initial connection and adhesion stability to non-noble metal substrates
The anisotropic conductive composition may be used to assemble chip-on-glass, flip chips, contactiess smart-card module, COF, COB, and RFiD The anisotropic conductive composition may be placed in between a semiconductor component and a non-noble metai substrate, activate the composition by means of thermo-compression, and allowing the chip and the substrate to adhere.
The following examples are for purpose of illustration and not intended to limit the scope of the invention in any manner.
EXAMPLES
Example 1. Preparation of Samples
Anisotropic conductive compositions of listed in Table 1 were prepared as follows (1 ) resins, rheoiogy modifier, adhesion promoter and corrosion inhibitor (Formulation 1 ) were mixed at a high speed with SpeedMixer (FlackTek) until homogenous, (2) curing agent was added and mixed at a medium speed, until the mixture was homogenous; (3) conductive fillers were added and mixed at a medium speed, until the mixture was homogenous, and (4) the mixture was degassed for five minutes in a vacuum chamber with >28 in Hg
Table 1 Composition
Example 2. Preparation of a Package
Each sample was then used to assemble a package using a thermo-compression process. Each composition was placed in between a 1 mm shorted die (commonly known as dummy die) and etched aluminum antenna (TOYO Al antenna) The bond line temperature profile was 6 sec at 18O0C, and the bond force was 3N. Example 3 Evaluation of Package in SJCR and DSS
Packages were then subjected to reliability testing in 85°C and 85% relative humidity chamber (ESPΞC Corp LHU- 1 13) At specific intervals, the single joint contact resistance (SJCR) was measured and reported in Table 2 Also, the die shear strength (DSS) was measured by Dage Series 4000 reported in Table 3
*Non-conductιve
**Average and standard deviation was not calculated
SJCR was measured with a Multimeter Two-Probe The SJCR values of Formulation 1 had consistent and overall stable electrical stability over Comparative A. Table 3 Die Shear Strength (DSS)
Formulations 2-4 had the components as Formulation 1 , except a different corrosion inhibitor/oxygen scavengers were used, as indicated in Table 3. The DSS indicated that the formulations with corrosion inhibitor and/or oxygen inhibitors provided overall improved long term shear strength even under 85CC/85%RH for 7 days. Furthermore, the package assembled with corrosion inhibitor and/or oxygen inhibitors had more consistent die shear strength than Comparative A Example 4 Work-life and Screen Printing Evaluation
The same formulation also provides excellent reliability and screen print life with other commercially available nickel particles available from Novamet (Tables 4 and 5) Screen pπntability was evaluated utilizing Formulation 1. A fixed amount of this formulation was stressed with constant shear at room temperature, and viscosity was measured at 0, 1 , 2, 4, 6 and 8 hour intervals in two frequencies. As shown in Table 4, the viscosity of Formation 1 had minimal change over the entire eight hours. Table 4 Work-life Formulation 1
The same material used in the Screen Printing Evaluation of above was used to assemble packages, as described in Example 2. The initial SJCR was measured for each package and they were subjected to 85°C/85%RH. At 20 hours, 5 days and 7 days, the SJCR were measured and recorded in Table 5 As shown in Table 5, the SCJR was consistently stable and there was no degradation of resistance through the whole print life Table 5 SCJR and Print life
Formulation 1 Aging condition 85°C/85% RH
Initial (Ω) 20hr {Ω) 5 days (Ω) 7days (Ω)
O hr 0.29 0 31 0 47 0 38
0.27 0 27 0 45 0 39
0.31 0 28 0 49 0 37
0 hr Ave + S. D. 0.29 + 0.02 0.29 + 0.02 0.47 + 0.02 0.38 + 0.01
1 hr 0.32 0.36 0 61 0 41
0.3 0 28 0 45 0 39
0 32 0 32 0 53 0.44
1 hr Ave + S.D. 0.31 + 0.01 0.32 + 0.04 0.53 + 0.08 0.41 + 0.03
2hr 0.33 0 38 0.54 0 53
0.31 0 3 0.51 0.47
0.29 0 29 0 49 0 41
2hr Ave + S. D. 0.31 + 0.02 0.32 + 0.05 0.51 + 0.03 0.47 + 0.06
4hr 0 31 0 31 0.43 0 37
0.33 0 37 0 39 0 37
0 32 0.39 0.4 0 38
4hr Ave + S. D. 0.32 + 0.01 0.36 + 0.04 0.41 + 0.02 0.37 + 0.01
6hr 0.33 0.41 0 39 0 35
0.29 0.37 0 38 0.38
0.33 0.38 0.35 0 38
6hr Ave + S.D. 0.32 + 0.02 0.39 + 0.02 0.37 + 0.02 0.37 + 0.02
8hr 0.29 0.37 0 35 0.38
0.3 0 35 0 37 0.41
0 33 0.37 0.32 0.39
8hr Ave ^ S.D. 0.31 + 0.02 0.36 + 0.01 0.35 + 0.03 0.39 + 0.02
Many modifications and variations of this invention can be made without departing from its spirit and scope, as will be apparent to those skilled in the art The specific embodiments described herein are offered by way of example only, and the invention is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled
Claims
Claims
1 An electronic package comprising a semiconductor attached to a non-noble metal substrate with an anisotropic conductive composition, wherein said anisotropic conductive composition comprises
(a) a polymeric resin,
(b) a corrosion inhibitor and/or an oxygen scavenger, (d) a curing agent, and
(d) conductive fillers
2 The electronic package of claim 1 , wherein the z-axis electrical resistance of said package increases less than four times the initial z-axis electrical resistance under 850C and 85% relative humidity for at least 1000 hours
The electronic package of claim 1 , wherein the polymeric resin is selected from the group consisting of polyaniline, polypyrrole, polythiophene, polyfuran, polyphenyleπe and mixtures thereof
The electronic package of claim 1 , wherein the polymeric resin is selected from the group consisting of vinyl, acrylic, phenolic, phenoxy, epoxy, maleimide, polyesters, polyimide, polyurethanes, polyolefins, polysulfide, nitrile, silicone resins and mixtures thereof
The electronic package of claim 1 , wherein the corrosion inhibitor is selected from the group consisting of aromatic tπazole imidazole thiazole, phosphorous-based compound and mixtures thereof
The electronic package of claim 5, wherein the aromatic triazole is selected from the group consisting of benzotriazole, toiyltriazole, carboxybenzotπazole, sodium toiyltriazole benzimidazole, rnercaptobenzothiazole and mixtures thereof
The electronic package of claim 5, wherein the imidazole is selected from the group consisting of hexamethyleneimide, decamethyleneimide and mixtures thereof
The electronic package of claim 5, wherein the thiazoie is selected from the group consisting of 1 ,3-thιazole, benzothiazoles, 2,4-dimethylthιazol, 2-(tπmethylsιlιyl)thιazole 2- (dιmethylamιno)thιazole, thiazolium salt and mixtures thereof
The electronic package of claim 5, wherein the phosphorous-based compound is selected from the group consisting of diphosphate ester, polyhydroxy amides, phosphonoxy ester phosphate salts and mixtures thereof
The electronic package of claim 1 , wherein the oxygen scavenger is selected from the group consisting of hydroquinone, carbohydrazide, trihydroxybenzene, aminophenol hydrazine, pyrogallol, carbohydrazone, polyethyleneamine, cyclohexaπedione, hydroxylamine, methoxypropylamine, cyclohexylamine, diethylethanolamine, hydroxyalkylhydroxylamine, tetrasubstituted pheπylenediamines, morpholinohexose reduction, keto-gluconates, amine bisulfites, lactone derivatives, phenol derivatives, substituted quinolines and mixtures thereof
The electronic package of claim 1 , wherein the curing agent is selected from the group consisting of 2-methylιmιdazole, 2-phenyIιmιdazole, 2-phenyl-4-methy!ιmιdazo!e, 2-ethyl-4 methylimidazole, 2-undecylιmϊdazole, 1-benzyl-2-methylιmιdazole, 1 -cyanoethyl-2- methyhmidazole, 1 -cyanoethyl-2-ethyl-4-methylιmιdazole and mixtures thereof
The electronic package of claim 1 , wherein the conductive fillers are selected from the group consisting of silver copper, gold, palladium, platinum, nickel, gold or silver-coated nickel, carbon black, carbon fiber, graphite aluminum indium tin oxide, silver coated copper, silver coated aluminum, metallic coated glass spheres, metallic coated filler, metallic coated polymers, silver coated fiber, silver coated spheres, and antimony doped tin oxide and mixtures thereof
The electronic package of claim 1 , wherein the composition further optionally comprising diluents, flow additives, rheology modifiers, inert fillers, defoamers, colorants and adhesion promoters and mixtures thereof
The electronic package of claim 1 , wherein the non-noble metal substrate is selected from the group consisting of stamped aluminum, etched aluminum, etched copper and vapor deposited copper
The electronic package of claim 14, wherein the non-noble metal substrate is seiected from the group consisting of aluminum and etched aluminum.
The electronic package of claim 1 , wherein said electronic package is selected from the group consisting of RFID, chip-on-flex, chip-on-board and flip chip
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US91222307P | 2007-04-17 | 2007-04-17 | |
| US60/912,223 | 2007-04-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2008130955A1 true WO2008130955A1 (en) | 2008-10-30 |
Family
ID=39875866
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US2008/060405 WO2008130955A1 (en) | 2007-04-17 | 2008-04-16 | Corrosion-resistant anisotropic conductive compositions |
Country Status (2)
| Country | Link |
|---|---|
| TW (1) | TW200910382A (en) |
| WO (1) | WO2008130955A1 (en) |
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| DE102018105987A1 (en) * | 2017-03-15 | 2018-09-20 | Nihon Tokushu Toryo Co., Ltd. | Antistatic composition for a vehicle, vehicle and method of manufacturing a vehicle |
| US20190390037A1 (en) * | 2018-06-20 | 2019-12-26 | The Boeing Company | Conductive compositions of conductive polymer and metal coated fiber |
| CN113260464A (en) * | 2019-12-23 | 2021-08-13 | 泰克大洋工业株式会社 | Laminate and method for preventing rust |
| CN115584503A (en) * | 2022-10-19 | 2023-01-10 | 安徽万磁电子有限公司 | Sintered neodymium-iron-boron-nickel-copper-nickel coating deplating process capable of reducing corrosion of base material |
| CN115584231A (en) * | 2022-09-29 | 2023-01-10 | 哈尔滨工业大学（深圳） | Modified isotropic conductive adhesive for packaging and preparation method thereof |
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| US6834612B2 (en) * | 2000-05-09 | 2004-12-28 | 3M Innovative Properties Company | Method and apparatus for making particle-embedded webs |
| US7034403B2 (en) * | 2003-04-10 | 2006-04-25 | 3M Innovative Properties Company | Durable electronic assembly with conductive adhesive |
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- 2008-04-16 WO PCT/US2008/060405 patent/WO2008130955A1/en active Application Filing
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| US5830584A (en) * | 1996-01-16 | 1998-11-03 | Seagate Technology, Inc. | Bicrystal cluster magnetic recording medium |
| US6834612B2 (en) * | 2000-05-09 | 2004-12-28 | 3M Innovative Properties Company | Method and apparatus for making particle-embedded webs |
| US7034403B2 (en) * | 2003-04-10 | 2006-04-25 | 3M Innovative Properties Company | Durable electronic assembly with conductive adhesive |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102018105987A1 (en) * | 2017-03-15 | 2018-09-20 | Nihon Tokushu Toryo Co., Ltd. | Antistatic composition for a vehicle, vehicle and method of manufacturing a vehicle |
| US10428227B2 (en) | 2017-03-15 | 2019-10-01 | Nihon Tokushu Toryo Co., Ltd. | Antistatic composition for vehicle, vehicle, and method for manufacturing vehicle |
| DE102018105987B4 (en) | 2017-03-15 | 2022-11-03 | Nihon Tokushu Toryo Co., Ltd. | Antistatic composition for a vehicle, vehicle and method of making a vehicle |
| US20190390037A1 (en) * | 2018-06-20 | 2019-12-26 | The Boeing Company | Conductive compositions of conductive polymer and metal coated fiber |
| US11152131B2 (en) * | 2018-06-20 | 2021-10-19 | The Boeing Company | Conductive compositions of conductive polymer and metal coated fiber |
| US11875914B2 (en) | 2018-06-20 | 2024-01-16 | The Boeing Company | Conductive compositions of conductive polymer and metal coated fiber |
| CN113260464A (en) * | 2019-12-23 | 2021-08-13 | 泰克大洋工业株式会社 | Laminate and method for preventing rust |
| CN115584231A (en) * | 2022-09-29 | 2023-01-10 | 哈尔滨工业大学（深圳） | Modified isotropic conductive adhesive for packaging and preparation method thereof |
| CN115584231B (en) * | 2022-09-29 | 2023-11-03 | 哈尔滨工业大学（深圳） | Modified isotropic conductive adhesive for packaging and preparation method thereof |
| CN115584503A (en) * | 2022-10-19 | 2023-01-10 | 安徽万磁电子有限公司 | Sintered neodymium-iron-boron-nickel-copper-nickel coating deplating process capable of reducing corrosion of base material |
| CN115584503B (en) * | 2022-10-19 | 2024-05-17 | 安徽万磁电子有限公司 | Sintered NdFeB nickel copper nickel plating stripping process for reducing substrate corrosion |
Also Published As
| Publication number | Publication date |
|---|---|
| TW200910382A (en) | 2009-03-01 |
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