CN106057292B - Substrate with conductive film, method for producing same, and conductive paste for polyimide substrate - Google Patents
Substrate with conductive film, method for producing same, and conductive paste for polyimide substrate Download PDFInfo
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- CN106057292B CN106057292B CN201610204778.3A CN201610204778A CN106057292B CN 106057292 B CN106057292 B CN 106057292B CN 201610204778 A CN201610204778 A CN 201610204778A CN 106057292 B CN106057292 B CN 106057292B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
- H01B5/14—Non-insulated conductors or conductive bodies characterised by their form comprising conductive layers or films on insulating-supports
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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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
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Abstract
The invention provides a substrate with a conductive film, which can be fired at a low temperature of 300℃ or less and has a silver conductive film having a conductivity and an excellent adhesion to a polyimide substrate, a method for producing the same, and a conductive paste used for the substrate. The conductive paste uses, as the silver powder, a silver powder to which an adhesion coating agent containing a rosin, fatty acid, or amine coating agent is attached in a mass ratio of 2.3 (%) or less to the silver powder, and therefore, even if the firing treatment is performed at a low temperature of 300 (DEG C) or less, the sintering of the silver powder is sufficiently performed, and therefore, high conductivity and high adhesion to a polyimide substrate can be obtained. Therefore, in the substrate with a conductive film, the constituent components of the silver conductive film and the polyimide substrate intrude into each other in a range of the thickness of the silver conductive film or less, and the uneven surface formed by the intrusion becomes an interface therebetween, and therefore, the conductivity and the adhesiveness are improved as the contact area is increased.
Description
Technical Field
The present invention relates to a substrate with a conductive film, which includes a conductive film on a polyimide substrate, a method for producing the same, and a conductive paste suitable for forming the conductive film.
Background
For example, a conductive paste used for forming wiring of a circuit board, forming an electrode of an electronic component, and the like contains a conductive powder, a resin binder, an organic solvent, and an inorganic filler such as a glass frit, which is contained as necessary. The conductive paste is roughly classified into a thermosetting type capable of forming a conductor film on a substrate by performing heat treatment at a low temperature of substantially 300 (deg.c) or less and a firing type capable of forming a conductor film by performing firing treatment at a temperature of 400 (deg.c) or more.
In the former thermosetting type, a thermosetting resin is used as a resin binder, and the thermosetting resin is cured by heat treatment to form a conductive film. This type has an advantage that it is unnecessary to select a substrate material because of a low processing temperature, but the conductive powders are fixed only by a resin binder in a state of being in contact with each other and the resin remains, so that there are difficulties in that the resistance value is high and the heat resistance and long-term reliability are low.
On the other hand, in the latter firing type, the conductive powder itself is fired by firing treatment, or in addition, the glass frit is fired to form a conductive film. This type has advantages of low resistance value, high heat resistance and high long-term reliability because the conductive powder is sintered while the resin is burned off, but has a difficulty that it cannot be applied to a resin substrate and the manufacturing cost is high because a high-temperature baking treatment is required.
Prior art documents
Patent document 1: japanese laid-open patent publication No. 2006-310022
Patent document 2: japanese patent laid-open publication No. 2011-252140
Patent document 3: japanese patent laid-open publication No. 2011-
Disclosure of Invention
Polyimide substrates, which are a kind of resin substrates, have high heat resistance and excellent flexibility, and therefore are widely used as substrates for electronic devices such as mobile terminals. The mainstream method for forming wiring on a polyimide substrate is a method for patterning by etching copper by pressure bonding, and thick film formation by screen printing or the like has been studied in order to reduce the resistance of a conductor wiring. As described above, since a conductive paste of a fired type cannot be used for a resin substrate, attempts have been made to improve a conductive paste of a thermosetting type, but sufficient conductivity has not been obtained.
For example, there has been proposed a conductive paste containing a conductive powder, a solvent, and a binder containing one or two or more selected from an aluminum compound and a silane coupling agent (see patent document 1). The conductive paste was dried at 200 (DEG C) to form a conductive film, and the specific resistance was 2.9X 10-5(Ω·cm)～6.1×10-5About (. omega. cm), the value remained relatively high. It is considered that the aluminum compound and the silane coupling agent cause a decrease in conductivity.
In addition, a method has been proposedA conductive ink comprising: the tap density is 1.0 to 10.0 (g/cm)3) D50 has a particle size of 0.3 to 5(μm) and a BET specific surface area of 0.3 to 5.0 (m)2Conductive particles of/g); an epoxy resin having a number average molecular weight of 10000 to 300000 and a hydroxyl value of 2 to 300 (mgKOH/g); and 0.2 to 20 parts by weight of a metal chelate compound capable of undergoing an alcohol exchange reaction with a hydroxyl group in the epoxy resin per 100 parts by weight of the epoxy resin (see patent document 2). The conductive ink is described to be used for printing and forming a high-precision conductive pattern, has excellent adhesion to a polyimide substrate, is of a thermosetting type as in the paste, and has a resistivity as high as 5.0X 10-5About (. omega. cm), the conductivity was insufficient.
On the other hand, for example, a firing type conductive paste has been proposed which contains a metal powder component composed of a group of metal particles 1 having an average primary particle diameter of 50(nm) or less and a group of metal particles 2 having an average primary particle diameter of 100(nm) or more; a thermoplastic resin; and a dispersion medium, wherein the ratio of the mass of the metal to the total mass of the metal and the resin is 94 to 98 (%) (see patent document 3). According to this conductive paste, a film is formed on a polyimide substrate by screen printing or the like, and the film is fired at a low temperature of about 200 (deg.C) to obtain a conductive film having both conductivity and adhesiveness.
However, the conductive paste has not replaced copper bonding wires, and further improvement is desired. The conductivity is improved to some extent but is not sufficient, and moreover, since fine metal powder of 50(nm) or less is required, the cost is high and the workability is poor. Patent document 3 describes a comparative example in which only metal particles having an average particle diameter of 100(nm) or more are used as the conductive paste having low conductivity, and this is considered to be because sintering of the metal powder has not sufficiently proceeded. In order to improve the sinterability, a fine powder of 50(nm) or less is mixed.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a substrate with a conductive film having silver conductive film excellent in conductivity and adhesion to a polyimide substrate, a method for producing the same, and a conductive paste for a polyimide substrate that can be used for producing the substrate with a conductive film.
In order to achieve the object, the gist of the invention 1 is a substrate with a conductive film including a conductive film containing silver as a conductor component on one surface of a polyimide substrate, and constituent components of the conductive film and the polyimide substrate intrude into each other into the other across an interface therebetween in a range not more than a thickness dimension of the conductive film, and a surface of unevenness formed thereby becomes the interface.
In addition, the gist of the 2 nd invention for achieving the above object is a method for manufacturing a substrate with a conductive film in which a conductive film containing silver as a conductive component is formed on a polyimide substrate, the method including: (a) a paste coating step of coating a conductive paste containing silver powder, a resin binder and an organic solvent in a predetermined pattern on the polyimide substrate, wherein a predetermined amount of a coating agent containing at least 1 of rosin, fatty acid and amine is adhered to the surface of the silver powder; and (b) a firing step of firing the silver at a maximum temperature of 250 to 300℃ to form a conductive film from the conductive paste.
The invention of claim 3 for achieving the above object is a conductive paste for a polyimide substrate for producing a substrate with a conductive film by forming a conductive film on a polyimide substrate, comprising silver powder, a resin binder and an organic solvent, wherein the silver powder is a silver powder to which a coating agent is attached, and the coating agent comprising at least 1 of rosin, fatty acid and amine is attached to the surface in an amount of 2.3 (%) or less in mass ratio to the silver powder.
According to the invention of claim 1, since the components of the conductive film and the polyimide substrate intrude into each other in a range not more than the thickness of the conductive film, and the uneven surface formed by the intrusion becomes an interface therebetween, the conductivity and the adhesiveness are improved as the contact area is increased. Therefore, a substrate with a conductive film having high conductivity and high adhesion to a polyimide substrate can be obtained.
Further, according to the above-mentioned invention 2, in the case of producing a substrate with a conductive film by forming a conductive film on a polyimide substrate, since the conductive paste to be applied is used as silver powder and silver powder having an adhesive coating agent containing a coating agent of rosin, fatty acid or amine adhered to the surface thereof in the paste coating step, sintering proceeds sufficiently even when the firing treatment is performed at a low temperature in the range of 250 to 300 (deg.c) in the firing step, and thus a substrate with a conductive film having high conductivity and high adhesion to a polyimide substrate can be obtained. When the firing temperature is less than 250 (deg.C), the sintering does not proceed sufficiently, while when it exceeds 300 (deg.C), the conductivity and adhesion are not particularly improved, and thus, there is merely a problem that excessive heat is applied to the polyimide substrate.
In addition, if the conductive paste containing silver powder as a conductive component is not a special paste using the fine powder of 50(nm) or less, sintering does not occur at a low temperature of 300 (DEG C) or less in general. Therefore, although a thermosetting paste is generally used for a resin substrate such as a polyimide substrate, high conductivity cannot be obtained since silver powder is fixed by a thermosetting resin in a state of being in contact with each other. However, in the present invention, the silver powder itself is sintered, not by the thermosetting resin. The reason for such an improvement in sinterability is not clear, but it is considered that as silver sintering progresses, the contact area between the surface of the polyimide substrate and the film containing silver powder increases, and the coating agent adhering to the silver powder acts as a sticking agent or a reaction accelerator on the contact interface.
Further, according to the above-mentioned invention 3, since the silver powder is a silver powder in which an adhesion coating agent containing a coating agent of rosin, fatty acid or amine is adhered in a range of 2.3 (%) or less in terms of a mass ratio to the silver powder, sintering of the silver powder is sufficiently performed even when the firing treatment is performed at a low temperature of 300 (deg.c) or less, preferably 270 (deg.c) or less, and therefore, high conductivity and high adhesion to the polyimide substrate can be obtained. Further, if the coating agent is slightly attached to the silver powder, the sinterability of the silver powder can be improved in accordance with the amount thereof, but if it exceeds 2.3 (%), the coating agent becomes hard to burn through during firing, and the film density is lowered, resulting in a decrease in conductivity.
Here, in the invention 1, it is preferable that the silver of the conductive film is sintered. That is, the substrate with a conductive film according to claim 1 is a substrate in which a conductive film is formed on a polyimide substrate using a firing type conductive paste. Therefore, silver, which is a conductive component in the conductive film, is sintered, and thus has high conductivity.
In the invention according to claim 2, it is preferable that the coating agent adhering to the surface of the silver powder is present in an amount of 2.3 (%) or less in terms of a mass ratio to the silver powder. If the coating agent is slightly attached, the sinterability of the silver powder can be improved in accordance with the amount, but if it exceeds 2.3 (%), the coating agent becomes hard to burn through during firing, and the film density is lowered, resulting in a decrease in conductivity.
In the conductive paste, the silver powder preferably has an average particle diameter of 0.5(μm) or less. The larger the silver particle diameter, the lower the sinterability, and when it is 1(μm) or more, the sintering is remarkably difficult, and the resistance value is increased.
Preferably, the conductive paste and the conductive film do not substantially contain glass. The phrase "substantially not containing glass" means that glass is ideally not contained at all, but is allowed to be contained to such an extent that characteristics such as sinterability are not affected.
In the invention 2 and the invention 3, the resin binder is preferably burned through at a decomposition temperature of 250 (deg.c) or lower, that is, at a temperature lower than the firing temperature. In this case, since organic matter and carbide hardly remain in the formed conductive film, a substrate with a conductive film having higher conductivity and higher adhesion to a polyimide substrate can be obtained. Acrylic resins are preferred if printability and workability are also taken into consideration. For example, a polymer of isobutyl methacrylate and having an average molecular weight of 16 ten thousand is exemplified. Further, it is not necessary to lower the decomposition temperature of the resin binder than the firing temperature. For example, a resin binder having a decomposition temperature of 300 (DEG C) or more may be used. In such a case, since the silver powder can be sufficiently sintered according to the invention of the present application, even if organic substances or carbides remain in the conductive film, sufficiently high conductivity can be obtained as compared with the conventional one.
Drawings
Fig. 1 is a view schematically showing a cross section of a substrate with a conductive film in which a silver conductive film is formed on one surface of a polyimide substrate according to an embodiment of the present invention.
Fig. 2 is a photograph of a cross section of the substrate with the conductive film of fig. 1 in the vicinity of the interface between the conductive film and the substrate.
Fig. 3 is a photograph showing a part of the cross section of fig. 2 in an enlarged manner.
Fig. 4 is a photograph of a cross section of the conductive film and the substrate near the interface of the substrate with the conductive film of the comparative example.
Fig. 5 is a photograph showing a part of the cross section of fig. 4 in an enlarged manner.
Fig. 6 is a diagram showing a cross-sectional shape of a conductive film of a substrate with a conductive film according to an embodiment of the present invention at a firing temperature.
Fig. 7 is an SEM photograph of the conductive film surface of the substrate with the conductive film according to the embodiment of the present invention.
Description of the reference numerals
10: silver conductive film, 12: polyimide substrate, 14: substrate with conductive film
Detailed Description
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are simplified or modified as appropriate, and the dimensional ratios, shapes, and the like of the respective portions are not necessarily accurately depicted.
Fig. 1 is a cross-sectional view of a substrate 14 with a conductive film in which a silver conductive film 10 of the present invention is formed on one surface of a polyimide substrate 12. The wiring board is used as an internal wiring board having flexibility, a flexible wiring board connecting a terminal of a movable portion and a terminal of a fixed portion, and the like in various electronic devices and the like. The silver conductive film 10 is made of, for example, silver having a thickness of about 1.0 to 8.0(μm), and has flexibility to deform when the polyimide substrate 12 is deformed.
The conductive film-attached substrate 14 is manufactured by preparing a conductive paste containing silver powder, a resin binder, and an organic solvent, forming a film on the polyimide substrate 12 by an appropriate printing method such as screen printing, gravure printing, offset printing, or inkjet printing, and performing a firing treatment to produce the silver conductive film 10. The silver powder is added as a silver powder to which a predetermined amount of coating agent adheres. The coating agent is any one of rosin, fatty acid, and amine. Examples of the fatty acid include stearic acid, lauric acid, oleic acid, linoleic acid, and capric acid. Further, as the amine, for example, dodecylamine is cited.
The silver powder of such an adhesion coating agent was prepared as follows. As the silver powder, a commercially available product prepared by a general wet method was used. Spherical powders having an average particle diameter of 0.07(μm), 0.10(μm), 0.5(μm), 0.8(μm), 0.9(μm), 1.0(μm), 1.4(μm), and 3(μm) were prepared. About 100(g) of the resulting mixture is taken out of a beaker, and about 1000(ml) of isopropyl alcohol is added thereto and sufficiently stirred. This was left overnight, and then the supernatant was discarded. Then, the mixture was poured into about 1000(ml) of isopropyl alcohol, stirred, and then left overnight. The washing operation is repeated 3 to 5 times. Thereby, the organic matter adhering to the silver powder was sufficiently removed.
Next, the coating agent was dissolved in isopropyl alcohol. Hereinafter, a case where rosin is used as a coating agent will be described as an example. As the rosin raw material, for example, gum rosin WW manufactured by Mikana chemical industry is used, and 1.0 to 2.5(g) of the gum rosin WW is taken out and added to 500(ml) of isopropyl alcohol and stirred. Next, the supernatant of the silver powder after the completion of the above-mentioned washing operation was discarded, and isopropyl alcohol in which rosin was dissolved was added thereto and sufficiently stirred. Next, the mixture was transferred to an eggplant-shaped flask, and heated and depressurized with warm water of 55 (deg.c) to 60 (deg.c) using an evaporator to vaporize isopropyl alcohol. The silver powder thus obtained was placed on a tray and left overnight. Thereafter, the silver powder particles having rosin adhered to the surfaces thereof were prepared by screening using a 200-mesh screen.
The amount of rosin adhering to the silver powder was measured by heating the silver powder to 900 (deg.C) with TG-DTA at a heating rate of 10 (deg.C/min). That is, the difference between the mass of 50 (. degree. C.) and the mass of 400 (. degree. C.) of TG was used as the amount of adhering rosin. The rosin deposition was adjusted by changing the amount of gum rosin WW added. For example, in the case of silver powder having a particle size of 0.1 (. mu.m), the amounts of rosin were 1.0 (%), 1.6 (%), and 2.0 (%), based on the amounts of gum rosin (gum rosin) of 1.2(g), 1.7(g), and 2.2 (g).
As described above, silver powder to which rosin adheres is prepared, and the resin binder and the organic solvent are mixed by a stirrer or the like. As the resin binder, for example, acrylic resin (EMB-002, manufactured by Mitsubishi レーヨ ン) is used, and as the organic solvent, for example, methanol is used. These were prepared in a predetermined amount, and a dispersion treatment was performed using a three-roll mill to gelatinize the paste, thereby obtaining a conductive paste. The acrylic resin was isobutyl methacrylate having an average molecular weight of about 16 ten thousand, taking screen printability and handling properties into consideration, which was burned out (flame え removed け る) at 250 ℃ or less. In the paste preparation, the viscosity at 25 (DEG C) -20(rpm) is adjusted to 180 to 200(Pa · s), for example, in order to achieve the same degree of printability.
Using the thus prepared conductive paste, thick film screen printing was performed on a polyimide substrate. The printing plate was made of SUS 400. In addition, printing conditions were set so that the width dimension of the printed film became 500(μm). After drying, the silver conductive film 10 is obtained by firing treatment at a temperature in the range of 250 to 300 (DEG C), the resin binder being burned through and the silver powder being sintered.
According to the present embodiment, since the silver powder to which the rosin, fatty acid, or amine-based adhesive coating agent is attached is used as the silver powder as described above, sintering of the silver powder is sufficiently performed even at a low temperature of 250 to 270 (deg.c) as described above, and thus, the conductive film 10 having a sheet resistance of about 2 to 8(m Ω/□), for example, and high adhesiveness can be obtained, and the conductive film 14 with a conductive film is present on the polyimide substrate 12.
Fig. 2 is an SEM image of a cross section of the conductive film-attached substrate 14 in the vicinity of the interface between the conductive film 10 and the polyimide substrate 12, and fig. 3 is an SEM image partially enlarged. The light color portion occupying the upper half or so of fig. 2 is the conductive film 10, and the dark color portion located below it is the polyimide substrate 12. As revealed by the SEM image, the conductive film 10 is sufficiently sintered to the extent that the grain boundaries disappear. In addition, irregularities are formed at the interface between the conductive film 10 and the substrate 12, and as shown by enlarging the boundary portion in fig. 3, silver and polyimide enter the other region.
Here, test results evaluated by variously changing the paste composition and the film formation conditions will be described. The following table 1 summarizes the results of the study on the presence or absence and type of the coating agent and the silver particle size. In Table 1, Nos. 1, 2, 6 and 13 are comparative examples, and the others are examples. The column "composition" shows the composition of the conductive paste in mass percent, with the silver amount being 68 to 75 (%), the glass amount being 0 to 2 (%), the resin binder amount being 5 to 6 (%), and the organic solvent amount being 20 to 24 (%). "resin/silver" is the percentage of resin amount relative to silver. In the column of "material", the "silver particle diameter" indicates the particle diameter of the silver powder before the coating agent used for each paste is attached, the "additive type" indicates the name of the material used as the coating agent for the silver powder, and the "attached amount" indicates the percentage of the attached coating agent to the silver powder as measured by TG-DTA as described above. The column "glass" is a composition system of the glass powder added to the paste. In the column of "test conditions and results", the "printing plate" is the mesh size, and the "printing thickness" is the film thickness after printing and drying. The "treatment temperature" is the highest holding temperature of the firing treatment, and the test results are shown for each treatment temperature. The "fired thickness" is the film thickness after firing, and the "resistance value" is the resistance value of the film-shaped conductor measured after firing by a digital multimeter based on a general 2-terminal method with a terminal interval of 10(cm) and a line width of 500(μm). The "sheet resistance (m Ω/□)" is a sheet resistance value after firing calculated from the above resistance value by the following equation. The thickness was 10(μm) in terms of thickness.
Sheet resistance (m Ω/□) — measured resistance (Ω) × (conductor width (mm)/conductor length (mm)) × (conductor thickness (μm)/converted thickness (μm))
The "tape strength" is obtained by pressing a transparent tape (CT-15153P manufactured by ニチバ ン) with a finger on the surface of a silver conductive film formed on a polyimide substrate after firing, and visually observing the appearance of the silver conductive film adhered to the surface of the peeled tape, and then determining the "tape strength" in which the silver conductive film is not adhered to the substantially entire surface of the pressed tape, the silver conductive film formed on the polyimide substrate remains as it is, and is defined as "○", a part of the silver conductive film is adhered to the pressed tape, a part of the silver conductive film formed on the polyimide substrate does not remain, and is defined as "△", a part of the silver conductive film is adhered to the pressed tape is 90 (%) or more, and a part of the silver conductive film formed on the polyimide substrate does not remain, and is defined as "x", and the above 3 stages are evaluated.
In table 1, as shown in comparative examples nos. 1 and 2, when silver powder without a coating agent was used, the polyimide substrate was not sintered, and therefore the sheet resistance was high and the tape strength was low. In particular, in sample No.1 using a silver powder having a particle size of 1 (. mu.m), the sheet resistance value was 32.3 (m.OMEGA./□) even when the firing was carried out at 270 (. degree.C), which was a significantly high value. In comparative example 13, which used a silver powder having dodecanethiol adhered as a coating agent, the sintering property was not improved, and the sheet resistance value was 65.1(m Ω/□) even when the firing was 270 (. degree. C.), but the tape strength was not obtained even though the firing was high.
On the other hand, in examples 3 to 5 and 7 to 12, rosin, stearic acid, lauric acid, oleic acid, linoleic acid, capric acid, and laurylamine as coating agents were attached in a mass ratio to silver of 0.16 to 2.3 (%), respectively, but all of them were sintered well by firing at 250 to 270 (deg.C) to obtain high conductivity, and the sheet resistance was 2.4 to 6.7 (m.OMEGA/□). The tape strength was also all "○". The samples 3 and 4 were evaluated in the same manner except that rosin was used for all of them and the silver particle size was 0.1(μm) and 0.07(μm). The conductivity of sample 3 having a large particle size was slightly large, and it was considered that the surface area of the silver powder having a fine powder was large, and therefore the coating amount was increased, and sample 6 was a polyimide substrate having a conductive film which was not sintered with silver powder having a sufficient strength, but the conductive film was not obtained.
FIGS. 4 and 5 are photographs of cross sections of example No.7 at a firing temperature of 230 (. degree. C.) and correspond to FIGS. 2 and 3, respectively. When the firing temperature is 230 (c), sintering is difficult because it is too low, and the interface between the silver conductive film 10 and the polyimide substrate 12 is also flat. Therefore, the sheet resistance value is high, and the tape strength is not obtained.
In addition, table 2 below summarizes the results of further evaluation by changing the conditions, and nos. 14 to 16 are the results of studying the particle size of the silver powder, in nos. 14 and 15 using the silver powder having the particle size of 0.5 to 1(μm), the sheet resistance value was 3.5 to 5.4(m Ω/□) at the firing temperature of 250 to 270(° c), high conductivity was obtained, and the tape strength was also "○", but in No.16 using the silver powder having the particle size of 3(μm), the sheet resistance value was inferior to those of them, particularly at the firing temperature of 250(° c), 10.5(m Ω/□) and the tape strength was also "x".
TABLE 2
In Nos. 17 to 19, the amount of the resin binder in the paste was varied in a range of 12.9 to 4.3 (%) in terms of mass ratio to silver, and under either condition, high conductivity with a sheet resistance value of 2.7 to 5.4 (m.OMEGA/□) and high tape strength evaluated at "○" were obtained by firing at 250 to 270 (. degree. C.) the amount of the resin in the paste was allowed to fall within a relatively wide range.
In addition, in Nos. 20 and 21, the resin binder in the paste was changed and evaluated, and in No.20, an acrylic resin having a high decomposition temperature (for example, EMB-398 made by Mitsubishi レーヨ ン having a decomposition temperature of about 300 (DEG C)) was used, and in No.21, ethyl cellulose (for example, EC-45 made by ダウケミカル having a decomposition temperature of about 450 (DEG C)) was used, and both of them, high conductivity and high tape strength having a sheet resistance value of 2.3 to 2.8 (m.OMEGA./□) could be obtained at a firing temperature of 250 to 270 (DEG C). Further, it is considered that since the decomposition temperatures of the above 2 types are high, at least a part of the silver conductive film 10 remains as an organic substance or carbide after firing, but from the above evaluation results, there is no problem at all even at such high decomposition temperatures, and it is understood that there is no concern even if the resin binder is completely fired through.
In addition, in nos. 22 to 24, the ratio of the resin binder to the organic solvent in the paste was changed, and the printing plate was changed to #400, #250, #165, and the printing thickness was changed to 3.2 to 10.1(μm). if the printing thickness was increased, the sinterability tended to be slightly deteriorated, and in nos. 22 and 23 having a printing thickness of 3.2(μm) at a firing temperature of 250 to 270 (deg.c), good results were obtained with a sheet resistance value of 2.7 to 3.7(m Ω/□) and a tape strength of "○", whereas in nos. 24 having a printing thickness of 10.1(μm), the tape strength of 250 (deg.c) was "×", while in nos. 24 was sufficiently fired at 270 (deg.c), a sheet resistance value of 4.8 (m/□) and a tape strength of "○", the tape strength was slightly deteriorated but the results were also found with a firing temperature of 270 (deg.c), and No.24 was also found to be good results with a sheet resistance value of 4.2 (m/364) and No.2 was also found to 364. c.
In No.25, the coating agent was not attached to the silver powder, but the coating agent was added to the paste, and the sheet resistance value was 332 (m.OMEGA./□) at a firing temperature of 250 (deg.C), and the sheet resistance value was remarkably large, and the electric conductivity was not obtained, and the tape strength was also "X". It was confirmed that a treatment of attaching the coating agent to the silver powder was necessary to improve the sinterability of the silver powder on the polyimide substrate.
Here, in the above-described embodiments, the results of evaluating the surface shape of the silver conductive film 10 after firing are described. Fig. 6 is a sectional view of the silver conductive film 10. The cross-sectional shape was measured by using SURFCOM 480A manufactured by tokyo precision, with a scanning speed of 1.5(mm/sec), a magnification of 10K, and a cutoff value of 0.8(mm), and a wiring pattern having a width of 500(μm) formed thereon was transversely cut in the width direction. In fig. 6, the vertical direction is the thickness direction of the silver conductive film 10, the horizontal direction is the width direction thereof, the central portion where unevenness is generated is the silver conductive film 10, and the flat portions on both sides thereof are the polyimide substrate 12. The temperature was the firing temperature of each evaluation sample, and example No.3 was measured at 250 (. degree. C.) and 270 (. degree. C.) and example No.22 was measured at 300 (. degree. C.). The same conductive paste as that used for the 325 c sample was used, and the measurement data is not shown in tables 1 and 2.
As shown in the cross-sectional shape of the measurement results, the silver conductive film 10 is formed by performing the firing treatment at a temperature ranging from 250 to 300 (deg.c), and as shown in fig. 2 and 3, the constituent components of the silver conductive film 10 and the polyimide substrate 12 intrude into each other to form an interface having a concave-convex shape, and as a result, the surface of the silver conductive film 10 has a sharp concave-convex cross-sectional shape as shown in fig. 6. The size of the unevenness is, as shown in a scale, about 2(μm) or less, which is the thickness of the silver conductive film 10.
On the other hand, when the silver conductive film 10 is fired at 325 (deg.c), the polyimide substrate 12 is significantly eroded by the silver conductive film 10, and a recess having a depth equal to or greater than the thickness of the silver conductive film 10 is formed. At this time, it is estimated that the constituent components of the polyimide substrate 12 substantially entirely intrude in the film thickness direction on the silver conductive film 10 side, and the sheet resistance value also increases. Thus, it is clear that defects such as cracking of the polyimide substrate 12 occur at the firing temperature of 325 (c) and that it cannot be used, and therefore the description in tables 1 and 2 is omitted.
Fig. 7 is a surface SEM photograph of the silver conductive film 10. As shown in the photograph, many pinholes were generated on the surface of the silver conductive film 10. It is considered that the irregularities appearing in fig. 6 are caused by such holes, but when the film thickness and the penetration depth of the constituent components are taken into consideration, the irregularities caused by the holes are ignored.
As described above, according to the present embodiment, since the silver conductive film 10 and the polyimide substrate 12 have their constituent components intrude into each other in the range of the thickness dimension of the silver conductive film 10 or less, and the uneven surface formed by the intrusion becomes the interface therebetween, the conductivity and the adhesiveness are improved as the contact area is increased. Therefore, the conductive film-equipped substrate 14 including the silver conductive film 10 having high conductivity and high adhesion to the polyimide substrate 12 can be obtained.
In addition, according to the present embodiment, when the substrate 14 with a conductive film is manufactured by forming the silver conductive film 10 on the polyimide substrate 12, since the applied conductive paste is silver powder in the paste application step and silver powder of the adhesive coating agent in which the coating agent containing rosin, fatty acid, or amine is adhered to the surface is used, sintering is sufficiently performed even if the firing treatment is performed at a low temperature in the range of 250 to 300 (deg.c) in the firing step, and the substrate 14 with a conductive film having the silver conductive film 10 with high conductivity and high adhesion to the polyimide substrate 12 can be obtained.
In addition, according to the present example, since the conductive paste uses, as the silver powder, a silver powder to which an adhesion coating agent containing a rosin, a fatty acid, or an amine coating agent is adhered in a mass ratio of 2.3 (%) or less with respect to the silver powder, sintering of the silver powder is sufficiently performed even if the firing treatment is performed at a low temperature of 300 (deg.c) or less, and therefore, high conductivity and high adhesion to the polyimide substrate 12 can be obtained.
The present invention has been described in detail with reference to the drawings, but the present invention can be implemented in other embodiments and various modifications can be made without departing from the scope of the present invention.
Claims (6)
1. A substrate with a conductive film, which is a polyimide substrate having a conductive film containing silver as a conductive component on one surface thereof,
the components of the conductive film and the polyimide substrate penetrate into each other across the interface between the conductive film and the polyimide substrate in a range not greater than the thickness of the conductive film, and the uneven surface formed thereby becomes the interface,
the sheet resistance value of the conductive film is 2.3-6.7 m omega/□,
the conductive film comprises rosin.
2. The substrate with a conductive film according to claim 1, wherein the conductive film is a conductive film in which silver is sintered.
3. A method for manufacturing a substrate with a conductive film, in which a conductive film containing silver as a conductive component is formed on a polyimide substrate, the method comprising:
a paste coating step of coating a conductive paste containing silver powder, a resin binder and an organic solvent, to which a predetermined amount of a coating agent containing at least 1 of rosin, fatty acid and amine is attached on the surface of the silver powder, in a predetermined pattern on the polyimide substrate; and
a firing step of firing the silver at a firing temperature in the range of 250 to 300 ℃ to form a conductive film from the conductive paste,
the resin binder is fired through at a temperature lower than the firing temperature.
4. A method for manufacturing a substrate with a conductive film, in which a conductive film containing silver as a conductive component is formed on a polyimide substrate, the method comprising:
a paste coating step of coating a conductive paste containing silver powder, a resin binder and an organic solvent, to which a predetermined amount of a coating agent containing at least 1 of rosin, fatty acid and amine is attached on the surface of the silver powder, in a predetermined pattern on the polyimide substrate; and
a firing step of firing the silver at a temperature in the range of 250 to 300 ℃ to form a conductive film from the conductive paste,
the coating agent adhering to the surface of the silver powder is present in an amount of 2.3% or less by mass relative to the silver powder,
the average particle diameter of the silver powder is in the range of 0.07 to 1.0 [ mu ] m.
5. A conductive paste for a polyimide substrate, which is used for producing a substrate with a conductive film by forming the conductive film on the polyimide substrate, is characterized by comprising a silver powder, a resin binder and an organic solvent,
the silver powder is a silver powder to which a coating agent is attached, and the coating agent containing at least 1 of rosin, fatty acid, and amine is attached to the surface in an amount of 2.3% by mass or less relative to the silver powder,
the sheet resistance value of the conductive film obtained by sintering the conductive paste for the polyimide substrate at a sintering temperature of 250-270 ℃ is 2.3-6.7 m omega/□,
the resin binder is fired through at a temperature lower than the firing temperature.
6. A conductive paste for a polyimide substrate, which is used for producing a substrate with a conductive film by forming the conductive film on the polyimide substrate, is characterized by comprising a silver powder, a resin binder and an organic solvent,
the silver powder is a silver powder to which a coating agent is attached, and the coating agent containing at least 1 of rosin, fatty acid, and amine is attached to the surface in an amount of 2.3% by mass or less relative to the silver powder,
the sheet resistance value of the conductive film obtained by sintering the conductive paste for the polyimide substrate at a sintering temperature of 250-270 ℃ is 2.3-6.7 m omega/□,
the average particle diameter of the silver powder is in the range of 0.07 to 1.0 [ mu ] m.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2015-078076 | 2015-04-06 | ||
| JP2015078076A JP6263146B2 (en) | 2015-04-06 | 2015-04-06 | Substrate with conductive film, method for producing the same, and conductive paste for polyimide substrate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN106057292A CN106057292A (en) | 2016-10-26 |
| CN106057292B true CN106057292B (en) | 2020-01-10 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201610204778.3A Expired - Fee Related CN106057292B (en) | 2015-04-06 | 2016-04-05 | Substrate with conductive film, method for producing same, and conductive paste for polyimide substrate |
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| Country | Link |
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| JP (1) | JP6263146B2 (en) |
| CN (1) | CN106057292B (en) |
| TW (1) | TWI687320B (en) |
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| CN108986986B (en) * | 2018-06-21 | 2020-06-16 | 浙江浙能技术研究院有限公司 | Method for manufacturing three-dimensional film electrode by using abrasive |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2006310022A (en) * | 2005-04-27 | 2006-11-09 | Mitsui Mining & Smelting Co Ltd | Electrically conductive paste, and flexible printed wiring board obtained using the same |
| JP5164239B2 (en) * | 2006-09-26 | 2013-03-21 | Ｄｏｗａエレクトロニクス株式会社 | Silver particle powder, dispersion thereof, and method for producing silver fired film |
| JP5139659B2 (en) * | 2006-09-27 | 2013-02-06 | Ｄｏｗａエレクトロニクス株式会社 | Silver particle composite powder and method for producing the same |
| JP2008108569A (en) * | 2006-10-25 | 2008-05-08 | Sekisui Chem Co Ltd | Sintering conductive paste |
| JP4986745B2 (en) * | 2007-07-05 | 2012-07-25 | Ｄｏｗａエレクトロニクス株式会社 | Silver paste |
| KR100935168B1 (en) * | 2007-09-21 | 2010-01-06 | 삼성전기주식회사 | Nonaqueous conductive nanoink composition |
| KR20100109416A (en) * | 2009-03-31 | 2010-10-08 | 디아이씨 가부시끼가이샤 | Electroconductive paste composition and the method of producing the same |
| JP2010287434A (en) * | 2009-06-11 | 2010-12-24 | Dowa Electronics Materials Co Ltd | Substrate with silver conductive film and method for manufacturing same |
| JP2011065783A (en) * | 2009-09-15 | 2011-03-31 | Dowa Electronics Materials Co Ltd | Conductive paste and wiring board employing the same |
| JP4702499B1 (en) * | 2010-02-05 | 2011-06-15 | 東洋インキＳｃホールディングス株式会社 | Conductive ink, laminate with conductive pattern and method for producing the same |
| JP5916633B2 (en) * | 2011-01-26 | 2016-05-11 | ナミックス株式会社 | Conductive paste and method for producing conductive film |
| WO2012169076A1 (en) * | 2011-06-10 | 2012-12-13 | Ｄｏｗａエレクトロニクス株式会社 | Bonding material and bonded object produced using same |
| JP2013139589A (en) * | 2011-12-28 | 2013-07-18 | Toda Kogyo Corp | Silver fine particles, method for producing the same, and conductive paste, conductive film, and electronic device containing the silver fine particles |
| WO2013115339A1 (en) * | 2012-02-02 | 2013-08-08 | 戸田工業株式会社 | Silver microparticles, method for producing same, and electronic device, conductive film, and conductive paste containing said silver microparticles |
| JP5939386B2 (en) * | 2012-04-16 | 2016-06-22 | 株式会社大阪ソーダ | Conductive ink composition |
| TW201522071A (en) * | 2013-09-10 | 2015-06-16 | Dainippon Ink & Chemicals | Laminate body, conductive pattern, electrical circuit, and method for producing laminate body |
-
2015
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2016
- 2016-02-16 TW TW105104466A patent/TWI687320B/en not_active IP Right Cessation
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Also Published As
| Publication number | Publication date |
|---|---|
| TWI687320B (en) | 2020-03-11 |
| TW201636203A (en) | 2016-10-16 |
| JP2016197582A (en) | 2016-11-24 |
| CN106057292A (en) | 2016-10-26 |
| JP6263146B2 (en) | 2018-01-17 |
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