EP0494235A1 - Solderable conductive polymer composition - Google Patents

Solderable conductive polymer composition

Info

Publication number
EP0494235A1
EP0494235A1 EP19900915143 EP90915143A EP0494235A1 EP 0494235 A1 EP0494235 A1 EP 0494235A1 EP 19900915143 EP19900915143 EP 19900915143 EP 90915143 A EP90915143 A EP 90915143A EP 0494235 A1 EP0494235 A1 EP 0494235A1
Authority
EP
European Patent Office
Prior art keywords
polymer composition
conductive polymer
polysulphide
epoxy
compound
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19900915143
Other languages
German (de)
French (fr)
Inventor
Pak Keung Pang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vesuvius Holdings Ltd
Original Assignee
Cookson Group PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cookson Group PLC filed Critical Cookson Group PLC
Publication of EP0494235A1 publication Critical patent/EP0494235A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/09—Use of materials for the conductive, e.g. metallic pattern
    • H05K1/092—Dispersed materials, e.g. conductive pastes or inks
    • H05K1/095—Dispersed materials, e.g. conductive pastes or inks for polymer thick films, i.e. having a permanent organic polymeric binder
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
    • C08G59/02—Polycondensates containing more than one epoxy group per molecule
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/08—Metals
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
    • 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 invention relates to a solderable conductive polymer composition which can be used for forming the conductive paths of a printed circuit.
  • a solderable conductive polymer composition which can be used for forming the conductive paths of a printed circuit.
  • a composition which comprises metallic particles distributed within an organic polymer binder.
  • Thick film inks are printable pastes comprising a conductive filler distributed within a curable or fusable binder.
  • the conductive filler is generally in the form of powder or flake of metal, for example silver or copper.
  • silver When silver is used it is sometimes alloyed with palladium to inhibit electro-migration, while copper may be coated with silver or a silver palladium alloy to improve the solderability of the resulting ink.
  • Nickel, aluminium, palladium and platinum/gold alloys have also been used.
  • the binders which are used fall into two classes; inorganic glasses and organic polymers.
  • organic binders have the advantage that they bind at lower temperatures than most inorganic glasses for example up to 300°C. They include compounds which would react together to form a polymer binder as well as thermoplastic polymers which would fuse in an analogous manner to inorganic glasses or dry in a similar fashion to paints. Reactive cross-linking polymers which, once cured, can withstand elevated temperatures are preferred.
  • the most commonly used organic polymers are epoxies, acrylics, silicones and polyimides.
  • One of the most preferred systems is silver distributed within an epoxy binder.
  • the metallic particles that is 70 to 80 wt % or more.
  • the metals used in these compositions are expensive and thus it is preferable to keep the content of them as low as possible.
  • conductivity another factor which has necessitated the use of quite high levels of metallic particles was the need to be able to solder the inks effectively to the components which are to be attached to the printed circuit.
  • solderability improves with an increasing content of metallic particles. Recent research has shown that solderability can also be improved in other ways, for example by etching the surface of the composition by bombardment with atomic or molecular species as described in our copending PCT patent application filed on 14th September 1989 and entitled "Preparing Articles for Soldering". However, this introduces a further stage in any manufacturing process.
  • Liquid polysulphide polymers have for many years been used in various industries. Those of lower molecular weight, for example molecular weights in the region of 1000 to 4000 which have comparatively low viscosities have been particularly employed as
  • a polysulphide polymer compound in the conductive polymer composition can increase the conductivity of the composition by a factor of 10, as described in DE 2546568A.
  • solderable silver-filled epoxy adhesives which have been reported are in general solvent-based systems that contain at least 85 weight percent of metal.
  • the present invention thus consists in a
  • solderable conductive polymer composition comprising metallic particles distributed within an organic polymer binder characterised in that it includes the reaction product of a polysulphide polymer compound with an epoxy compound.
  • the conductive polymer composition of the present invention can be based on any of the known conductive polymer systems, however a system based on epoxy resin is preferred.
  • epoxy resin that may be employed as the organic polymer binder include
  • the preferred epoxy resins are bisphenol-A and bisphenol-F. While any of the conventional metallic particles such as copper, nickel, aluminium, palladium or platinum may be employed it is preferred that the metallic
  • incorporation of an epoxidised polysulphide into metal filled epoxies having reduced metal content can result in a non-solvent based solderable conductive
  • the conductive polymer composition of the invention may include conventional reactive diluents if desired.
  • reactive diluents that may be used include both monofunctional and multifunctional compounds.
  • reactive diluents containing one reactive epoxy group include alkyl glycidyl ether where the alkyl group contains between 8 and 14 carbon atoms such as butyl glycidyl ether and ethylhexyl glycidyl ether; phenyl glycidyl ether; cresol glycidyl ether; and para-tertiary-butylphenyl glycidyl ether.
  • reactive diluents containing more than one reactive epoxy group include polyglycidyl ether of an aliphatic polyol, triglycidyl ether of
  • the epoxidised polysulphide polymer compound employed in the composition of the present invention may be provided by any epoxidised polysulphide polymer but the polymer will preferably be liquid and will have a viscosity similar to compounds traditionally used as reactive diluents for epoxy resin systems that is, it will preferably have a viscosity of only up to 500 centipoise at 25°C. This is so that the
  • an epoxidised polysulphide compound is ELP-3 marketed by Morton Thiokol Limited.
  • the epoxidised polysulphide is preferably present in the composition of the present invention in an amount of less than 4 wt.%.
  • the metallic particles are preferably present in the composition of the present invention in an amount of from 65 to 85 wt.%, most preferably about 77 wt.%.
  • the epoxidised polysulphide polymer compound may react with the organic binder on curing.
  • the present invention includes a solderable conductive polymer composition which has been cured and in which the epoxidised polysulphide polymer compound has reacted with other components of the composition.
  • composition of the present invention can be used to form the conductive pathways for a printed circuit, which may be a circuit board in which the circuit is printed on epoxy board or a membrane circuit in which the circuit is printed on flexible plastics material.
  • the epoxidised polysulphide compounds of the present invention can be formed according to the following reactions. Initially a polysulphide
  • Polysulphides which may be formed in this way include, for example poly(ethylene disulphide),
  • Such polysulphide can then be epoxidised by reaction with compounds with terminal epoxy groups as shown below where HS-R 1 - SH stands for a polysulphide.
  • MMC SF25 Degussa silver flake
  • MMC SF53 Degussa silver flake
  • the silver flake was then added and the material mixed until all the silver flake was dispersed uniformly into the liquid mixture.
  • the screw top was put on the container and sealed using PVC tape. The container was thereafter stored in a refrigerator.
  • formulations was 150°C for 1 hour.
  • component-A mixture 25 grams was prepared in a 30 cm 3 polypropylene container which had been cleaned using methanol and then air dried. All the liquid components were weighed into the container and a palette knife with a stainless steel blade was used to stir the mixture for five minutes. The silver flake was then added and the material mixed until all the silver flake was dispersed uniformly into the liquid mixture. The screw top was put on the
  • Component-B was prepared by the same method as component-A.
  • Components A and B were mixed in a 1:1 ratio by weight or by volume.
  • Solvent blend % weight (grams)
  • the semi-solid novalac epoxy resin was dissolved in the solvent blend to give component A.
  • dicyandiamide was dissolved in the solvent blend to give component B.
  • Components A and B were then mixed together, followed by addition of the polysulphide (if required) and then by the correct concentration of gold or silver.
  • the curing schedule for these formulations is 180°C for 1 hour.
  • the electrical volume resistivity and solderability of the gold and silver formulations are compared on an equal volume basis.
  • the container with the adhesive was taken from the refrigerator and its temperature allowed to reach equilibrium with that of the room temperature before removal of the PVC tape.
  • the EVR test specimen was prepared using a standard one inch by three inch glass slide pre-cleaned using methanol and air dried. Two strips of transparent adhesive tape parallel to each other and 0.3 cm apart were applied onto the glass slide. A drop of silver-filled epoxy adhesive was placed between the tapes and squeezed into a thin film using a palette knife to produce an adhesive fil 0.3 cm wide and at least 6.5 cm long.
  • the transparent tapes were then removed and the adhesive cured for one hour at 150°C.
  • the cured adhesive was then tested at room temperature.
  • the resistivity was measured using the following apparatus and conditions.
  • the circuit employed is illustrated in Figure 1.
  • the apparatus consists of a constant current source (1) which is a Keithley 228 programmable current/voltage source; a digital multimeter (2) which is a Keithley 195A multimeter which is zeroed and auto ranging; and linear four point probe (3) consisting of spring loaded copper probes with tungsten coated tips and having a
  • Adhesive 4 mounted on a glass slide 5 is positioned beneath the probe 3.
  • the potential difference for driving the current was 10 volts.
  • the delay time between each current step was 5 seconds.
  • the programmed current was Cycle range-
  • EVR (A/L) * (V//I) ohm cm Where - EVR is the electrical volume resistivity

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  • Chemical & Material Sciences (AREA)
  • Polymers & Plastics (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Conductive Materials (AREA)
  • Epoxy Resins (AREA)

Abstract

Composition polymère conductrice et brasable comprenant des particules métalliques réparties à l'intérieur d'un liant à base de polymère organique dont la caractéristique est qu'il inclut le produit réactionnel d'un composé de polymère polysulfure avec un composé époxy.Conductive and brazable polymer composition comprising metallic particles distributed inside an organic polymer-based binder, the characteristic of which is that it includes the reaction product of a polysulfide polymer compound with an epoxy compound.

Description

Solderable Conductive Polymer Composition
The invention relates to a solderable conductive polymer composition which can be used for forming the conductive paths of a printed circuit. In particular it relates to such a composition which comprises metallic particles distributed within an organic polymer binder.
In recent years much research has been directed to the development of printed conductors employing thick film inks for use in electronic assemblies.
Thick film inks are printable pastes comprising a conductive filler distributed within a curable or fusable binder. The conductive filler is generally in the form of powder or flake of metal, for example silver or copper. When silver is used it is sometimes alloyed with palladium to inhibit electro-migration, while copper may be coated with silver or a silver palladium alloy to improve the solderability of the resulting ink. Nickel, aluminium, palladium and platinum/gold alloys have also been used.
The binders which are used fall into two classes; inorganic glasses and organic polymers. Of these, organic binders have the advantage that they bind at lower temperatures than most inorganic glasses for example up to 300°C. They include compounds which would react together to form a polymer binder as well as thermoplastic polymers which would fuse in an analogous manner to inorganic glasses or dry in a similar fashion to paints. Reactive cross-linking polymers which, once cured, can withstand elevated temperatures are preferred. The most commonly used organic polymers are epoxies, acrylics, silicones and polyimides.
One of the most preferred systems is silver distributed within an epoxy binder. In order to obtain sufficient conductivity of the composition for it to be effective in providing a conductive path for a printed circuit it has been necessary to include quite high levels of the metallic particles that is 70 to 80 wt % or more. However, the metals used in these compositions are expensive and thus it is preferable to keep the content of them as low as possible. Apart from conductivity another factor which has necessitated the use of quite high levels of metallic particles was the need to be able to solder the inks effectively to the components which are to be attached to the printed circuit.
Solderability improves with an increasing content of metallic particles. Recent research has shown that solderability can also be improved in other ways, for example by etching the surface of the composition by bombardment with atomic or molecular species as described in our copending PCT patent application filed on 14th September 1989 and entitled "Preparing Articles for Soldering". However, this introduces a further stage in any manufacturing process.
Thus, it is desirable to find a way of increasing the conductivity of such compositions with a reduced proportion of metallic particles present but
maintaining solderability.
Liquid polysulphide polymers have for many years been used in various industries. Those of lower molecular weight, for example molecular weights in the region of 1000 to 4000 which have comparatively low viscosities have been particularly employed as
elastomeric modifiers for epoxy resins in the
production of coatings, adhesives and electronic encapsulants. Recently, various modified polysulphide polymers have been developed for particular uses and these include reaction products of polysulphide polymers with epoxy compounds such as those described in US 4689389 .
The inclusion of a polysulphide polymer compound in the conductive polymer composition can increase the conductivity of the composition by a factor of 10, as described in DE 2546568A.
However, these compositions are generally found not to be solderable. Compatibility between
metal-filled conducting epoxies and solders used in the semi-conductor industry is of great interest because of the possibility of reducing production cost. The solderable silver-filled epoxy adhesives which have been reported are in general solvent-based systems that contain at least 85 weight percent of metal.
It is desirable to develop a range of non-solvent based solderable metal filled epoxies. These filled epoxies should desirably contain less than 80 weight percent metal, no solvents and be solderable without any surface treatment.
The present invention thus consists in a
solderable conductive polymer composition comprising metallic particles distributed within an organic polymer binder characterised in that it includes the reaction product of a polysulphide polymer compound with an epoxy compound.
The conductive polymer composition of the present invention can be based on any of the known conductive polymer systems, however a system based on epoxy resin is preferred. Examples of epoxy resin that may be employed as the organic polymer binder include
bisphenol-A based resins, bisphenol-F based resins, epoxy novolak resins,
tetraglycidyl-4,4'-diaminodiphenylmethane and
triglycidyl ether of p-aminophenol. The preferred epoxy resins are bisphenol-A and bisphenol-F. While any of the conventional metallic particles such as copper, nickel, aluminium, palladium or platinum may be employed it is preferred that the metallic
particles comprise silver.
It has now surprisingly been found that
incorporation of an epoxidised polysulphide into metal filled epoxies having reduced metal content can result in a non-solvent based solderable conductive
composition.
In contrast addition of small quanties of unepoxidised polysulphide to known compositions reduces the resistivity of the formulation but results in a surface which is not solderable.
The conductive polymer composition of the invention may include conventional reactive diluents if desired. Examples of reactive diluents that may be used include both monofunctional and multifunctional compounds. Examples of reactive diluents containing one reactive epoxy group include alkyl glycidyl ether where the alkyl group contains between 8 and 14 carbon atoms such as butyl glycidyl ether and ethylhexyl glycidyl ether; phenyl glycidyl ether; cresol glycidyl ether; and para-tertiary-butylphenyl glycidyl ether. Examples of reactive diluents containing more than one reactive epoxy group include polyglycidyl ether of an aliphatic polyol, triglycidyl ether of
trimethylolpropane, cycloaliphatic diglycidyl ether, neopentylglycol diglycidyl ether, butanedioldiglycidyl ether, 1,6-hexanediol diglycidyl ether and resorcinol diglycidyl ether.
The epoxidised polysulphide polymer compound employed in the composition of the present invention may be provided by any epoxidised polysulphide polymer but the polymer will preferably be liquid and will have a viscosity similar to compounds traditionally used as reactive diluents for epoxy resin systems that is, it will preferably have a viscosity of only up to 500 centipoise at 25°C. This is so that the
compound does not have an adverse effect on the viscosity of the composition prior to curing. A further advantage may arise from the use of epoxidised polysulphide compounds in these formulations. This is because terminal mercaptan groups give the compound an unpleasant smell. If the compound is prepolymerised with an epoxy compound the amount of terminal
mercaptan groups is reduced and thus the mercaptan smell is reduced or obviated. An example of an epoxidised polysulphide compound is ELP-3 marketed by Morton Thiokol Limited. The epoxidised polysulphide is preferably present in the composition of the present invention in an amount of less than 4 wt.%.
The metallic particles are preferably present in the composition of the present invention in an amount of from 65 to 85 wt.%, most preferably about 77 wt.%.
As stated above, the epoxidised polysulphide polymer compound may react with the organic binder on curing. Thus, the present invention includes a solderable conductive polymer composition which has been cured and in which the epoxidised polysulphide polymer compound has reacted with other components of the composition.
The composition of the present invention can be used to form the conductive pathways for a printed circuit, which may be a circuit board in which the circuit is printed on epoxy board or a membrane circuit in which the circuit is printed on flexible plastics material.
The epoxidised polysulphide compounds of the present invention can be formed according to the following reactions. Initially a polysulphide
compound can be formed: 1. 2ClCH2CH2OH + HCHO
Ethyl ene Formaldehyde
Chlorohydrin
H+
ClCH2CH2OCH2CH2Cl+H2O
2. 6NaOH + (2x+2)S →2Na2Sx + Na2S2O3 + 3H2O
3. ClCH2CH2OCH2CH2Cl + 2Na2Sx + Na2S2O3
polysulphide.
Polysulphides which may be formed in this way include, for example poly(ethylene disulphide),
-(SCH2CH2S)n
or poly(butyl ether disulphide),
-(SCH2(CH2)3OCH2(CH2)3S)n-.
Such polysulphide can then be epoxidised by reaction with compounds with terminal epoxy groups as shown below where HS-R1- SH stands for a polysulphide. 1
V
H
in order to ensure that terminal epoxy groups are attained a molar excess of the epoxy compound should be employed.
In the following Examples the solderability of two single component and one two-component die attach silver-filled epoxy adhesives (Epo-tek H35-175M, Epo-tek H31 and Epo-tek H20E) manufactured by Epoxy Technology Inc. have been tested. These tests have then been used as a standard to compare the
solderability of silver-filled epoxies according to the invention and solvent-based gold-filled epoxy systems as described in DE 2546568.
In the drawings. Figure 1 is a diagram of the circuit employed for E.V.R. measurement.
EXAMPLES
Identity of chemicals
Quartex 1010 (Q1010) Bisphenol-A epoxy resin
WC 67 Butane-diσl diglycidyl ether
ERL 4221E 3,4-epoxycyclohexylmethyl-3,4- epoxy-cyclohexane-carboxylate
ELP-3 Epoxidized polysulphide
LP-3 Polysulphide
2PHZ-CN 1-cyanoethyl-2-phenyl-4,5-di
(cyano-ethoxymethyl) imidazole 2E4MZ-CN 1-cyanoethyl-2-ethyl-4-methylimidazole
A187 Gamma-glycidoxypropyltrimethoxy- silane
IMEO 3-4,5-dihydro imidazole-1-yl- propyltriethoxysilane
MMC SF25 Degussa silver flake MMC SF53 Degussa silver flake
AY5022 Johnson Matthey gold powder Preparation of non-solvent based silver-filled epoxies
(i) Single component formulation method A one component silver filled epoxy adhesive was prepared in a 60 cm3 polypropylene container which had been cleaned in methanol and then air dried. For a 50 gram batch of material (see formulation below), all the liquid components were weighed into the container and a palette knife with a stainless steel blade was used to stir the liquid mixture for
approximately five minutes. The silver flake was then added and the material mixed until all the silver flake was dispersed uniformly into the liquid mixture. The screw top was put on the container and sealed using PVC tape. The container was thereafter stored in a refrigerator.
Single component formulations
- The curing schedule for the single component
formulations was 150°C for 1 hour.
(ii) Two component formulation method
25 grams of component-A mixture was prepared in a 30 cm3 polypropylene container which had been cleaned using methanol and then air dried. All the liquid components were weighed into the container and a palette knife with a stainless steel blade was used to stir the mixture for five minutes. The silver flake was then added and the material mixed until all the silver flake was dispersed uniformly into the liquid mixture. The screw top was put on the
container and sealed using PVC tape. The container was thereafter stored at room conditions.
Component-B was prepared by the same method as component-A.
Components A and B were mixed in a 1:1 ratio by weight or by volume.
Two component formulations
The curing schedule for the two component formulations was 150°C for 30 minutes. Comparative example: Preparation of solvent based silver and gold filled epoxies
Solvent based formulation method
These may be prepared by the method described in DE 2546568. The solvent blend is composed of the following formulation:
Solvent blend: % weight (grams)
Methyl glycol 55
Diacetone alcohol 25
Acetone 15
Toluene 5
100
The semi-solid novalac epoxy resin was dissolved in the solvent blend to give component A. The
dicyandiamide was dissolved in the solvent blend to give component B. Components A and B were then mixed together, followed by addition of the polysulphide (if required) and then by the correct concentration of gold or silver.
Solvent based formulations
The following formulations are based on the
gold-filled epoxy described in DE 2,546,568.
The curing schedule for these formulations is 180°C for 1 hour.
In formulations U and V the weight % of gold is 89.18 and the volume % of gold is 36.40 excluding solvent.
In formulations W and X the weight % of silver is
81.76 and the volume % of silver is 36.40 excluding solvent.
The electrical volume resistivity and solderability of the gold and silver formulations are compared on an equal volume basis.
ELECTRICAL VOLUME RESISTIVITY MEASUREMENTS
Sample Preparation The container with the adhesive was taken from the refrigerator and its temperature allowed to reach equilibrium with that of the room temperature before removal of the PVC tape. The EVR test specimen was prepared using a standard one inch by three inch glass slide pre-cleaned using methanol and air dried. Two strips of transparent adhesive tape parallel to each other and 0.3 cm apart were applied onto the glass slide. A drop of silver-filled epoxy adhesive was placed between the tapes and squeezed into a thin film using a palette knife to produce an adhesive fil 0.3 cm wide and at least 6.5 cm long.
The transparent tapes were then removed and the adhesive cured for one hour at 150°C. The cured adhesive was then tested at room temperature.
Three samples of each formulation were made using the same method as that described above. The two component systems were premixed before use.
Test Method
Apparatus
The resistivity was measured using the following apparatus and conditions. The circuit employed is illustrated in Figure 1. The apparatus consists of a constant current source (1) which is a Keithley 228 programmable current/voltage source; a digital multimeter (2) which is a Keithley 195A multimeter which is zeroed and auto ranging; and linear four point probe (3) consisting of spring loaded copper probes with tungsten coated tips and having a
constant probe spacing of 1.5cm. Adhesive 4 mounted on a glass slide 5 is positioned beneath the probe 3.
Experimental conditions
The potential difference for driving the current was 10 volts. The delay time between each current step was 5 seconds. The programmed current was Cycle range-
Forward: -0.05 to +0.05 amps Step +0.01 amps Reverse: +0.05 to -0.05 amps Step -0.01 amps Test Method The equipment was connected as shown in the circuit diagram in Figure 1. The current source was switched on to supply a constant current I to the outer probes and the voltage V between the inner probes was measured with the digital multimeter. The thickness of the adhesives was measured using a digital
micrometer with a semi-spherical measuring anvil. An average value was taken of the difference between the thickness of the slide and thickness of the slide plus the adhesive measured at three different points. Calculation
EVR = (A/L) * (V//I) ohm cm Where - EVR is the electrical volume resistivity
A is the cross sectional area of adhesive (A = width * thickness)
L is the distance between the inner probes V is the voltage
I is the current
SOLDERABILITY OF SILVER AND GOLD-FILLED EPOXIES
Sample preparation
The samples were prepared as previously described. Test method
The equipment used comprised an RS soldering station with temperature control and a soldering iron. The solder tested was Arconium semi-conductor alloy 572B, composed of 92.5% Pb, 5% In and 2.5% Ag, having a melting point of 300°C and a soldering temperature of 310°C. The flux used was Alpha 709 containing >50% methanol and having a flash point of 16 deg.c.

Claims

CLAIMS :
1. A solderable conductive polymer composition comprising metallic particles distributed within an organic polymer binder characterised in that it includes the reaction product of a polysulphide polymer compound with an epoxy compound.
2. A solderable conductive polymer composition as claimed in claim 1 characterised in that the organic polymer binder comprises epoxy resin.
3. A solderable conductive polymer composition as claimed in claim 1 or claim 2 characterised in that the metallic particles comprise silver.
4. A solderable conductive polymer composition as claimed in any one of claims 1 to 3 characterised in that the reaction product of the polysulphide polymer compound and the epoxy compound has terminal epoxy groups.
5. A solderable conductive polymer composition as claimed in any one of claims 1 to 4 characterised in that the reaction product of a polysulphide polymer compound with an epoxy compound is present in an amount of up to 5 wt.%.
6. A solderable conductive polymer composition as claimed in any one of claims 1 to 5 characterised in that the metallic particles are present in an amount of 65 to 85 wt.%.
7. A solderable conductive polymer composition as claimed in claim 6 characterised in that the metallic particles are present in an amount of about 77 wt.%.
8. A conductive polymer composition as claimed in any one of claims 1 to 7 which has been cured and in which the reaction product of a polysulphide polymer compound with an epoxy compound has reacted with other components of the composition.
9. A printed circuit which includes conductive paths formed from a conductive polymer composition as
claimed in any one of claims 1 to 8.
EP19900915143 1989-09-27 1990-09-26 Solderable conductive polymer composition Withdrawn EP0494235A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8921742 1989-09-27
GB898921742A GB8921742D0 (en) 1989-09-27 1989-09-27 Conductive polymer composition

Publications (1)

Publication Number Publication Date
EP0494235A1 true EP0494235A1 (en) 1992-07-15

Family

ID=10663649

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900915143 Withdrawn EP0494235A1 (en) 1989-09-27 1990-09-26 Solderable conductive polymer composition

Country Status (3)

Country Link
EP (1) EP0494235A1 (en)
GB (1) GB8921742D0 (en)
WO (1) WO1991005354A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9126902D0 (en) * 1991-12-19 1992-02-19 Morton Int Ltd Polysulphide-modified epoxy resins
JPH06267784A (en) * 1992-11-04 1994-09-22 Du Pont Kk Conductive resin paste and laminated ceramic chip capacitor with terminal electrode consisting of same

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2546568A1 (en) * 1975-10-17 1977-04-21 Ted Bildplatten Electrically conductive adhesives - comprises epoxy resin polysulphide plasticiser and gold particles

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9105354A1 *

Also Published As

Publication number Publication date
WO1991005354A1 (en) 1991-04-18
GB8921742D0 (en) 1989-11-08

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