JPH09204816A - Conductive paste, conductive composition, and their usage as conductive connector - Google Patents

Conductive paste, conductive composition, and their usage as conductive connector

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Publication number
JPH09204816A
JPH09204816A JP1029596A JP1029596A JPH09204816A JP H09204816 A JPH09204816 A JP H09204816A JP 1029596 A JP1029596 A JP 1029596A JP 1029596 A JP1029596 A JP 1029596A JP H09204816 A JPH09204816 A JP H09204816A
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JP
Japan
Prior art keywords
paste
conductive
poly
composite
thermoplastic polymer
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.)
Granted
Application number
JP1029596A
Other languages
Japanese (ja)
Other versions
JP3111010B2 (en
Inventor
J Sanbusecchi Carlos
I Cooper Emmanuel
Marie Rorudan Judith
Anthony Gains Michael
S Saraf Ravi
Benton Boss Richard
Paul Ostlunder Stephen
エマニュエル・アイ・コーパー
カルロス・ジェイ・サンブセッチ
ジュディス・マリエ・ロルダン
ステファン・ポール・オストランダー
マイケル・アンソニー・ガインズ
ラビ・エフ・サラフ
リチャード・ベントン・ボス
Original Assignee
Internatl Business Mach Corp <Ibm>
インターナショナル・ビジネス・マシーンズ・コーポレイション
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Application filed by Internatl Business Mach Corp <Ibm>, インターナショナル・ビジネス・マシーンズ・コーポレイション filed Critical Internatl Business Mach Corp <Ibm>
Priority to JP08010295A priority Critical patent/JP3111010B2/en
Publication of JPH09204816A publication Critical patent/JPH09204816A/en
Application granted granted Critical
Publication of JP3111010B2 publication Critical patent/JP3111010B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00Printed circuits
    • H05K1/02Details
    • H05K1/09Use of materials for the conductive, e.g. metallic pattern
    • H05K1/092Dispersed materials, e.g. conductive pastes or inks
    • H05K1/095Dispersed materials, e.g. conductive pastes or inks for polymer thick films, i.e. having a permanent organic polymeric binder
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00Apparatus or processes for manufacturing printed circuits
    • H05K3/46Manufacturing multilayer circuits
    • H05K3/4611Manufacturing multilayer circuits by laminating two or more circuit boards
    • H05K3/4614Manufacturing multilayer circuits by laminating two or more circuit boards the electrical connections between the circuit boards being made during lamination

Abstract

(57) Abstract: A remeltable conductive paste and a composite material containing no flux composition are provided. The conductive paste of the present invention contains a thermoplastic polymer, a conductive metal powder, and an organic solvent system.
The present invention also provides a conductive composite material containing the above thermoplastic polymer and a metal. The metal comprises at least about 30% by volume of the total volume of the composite material. This composite material is formed from a paste at high temperature. This paste is used in the process of electrically connecting electrical and electronic components under the condition that the paste is converted into a composite material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste useful for forming a conductive connection between conductive members. The present invention further relates to a method of forming a conductive connection between conductive members using the above-mentioned conductive paste.

[0002]

BACKGROUND OF THE INVENTION Conductive compositions for forming conductive connections between conductive members such as pads on a chip and pads associated with printed circuits on a circuit board are well known to those skilled in the art. is there. In fact, conventional solder compositions consisting of eutectic gold, such as lead-tin alloys, have long been known. However, such materials require a flux composition to remove oxides on the surface of the solder metal. These flux materials are acidic in nature and corrode high value electrical components that are electrically connected, and therefore are typically removed with a solvent. However, the conventional solvent for removing the flux has an environmental problem, and the use of the solvent complicates the manufacturing process. Therefore, the use of flux materials is declining for electrical assemblies that require the connection of expensive electrical components used in current electrical and electronic devices such as computers.

In view of the known drawbacks of eutectic alloys, a new conductive paste has been developed. Usually, these pastes include a conductive metal powder and a thermosetting resin material. After applying such materials to electrical components, they are heated to form electrical connections. The thermosetting resin cures during this heating. It is known to use non-oxidizing metals as conductive powders in these new pastes, eliminating the need for flux, but such materials are characterized by the disadvantageous property of not remelting. . Those skilled in the art are aware that thermosetting resins form cross-linked structures as they cure. A polymer having a crosslinked structure cannot be remelted or dissolved. Therefore, such electrically connected components are very expensive, but if necessary, simply heat or remelt the conductive paste to disconnect the components and use them before Or, it cannot be easily reconnected using a new identical paste.

A recent development that has led to significant advances in the industry is described in US Pat. No. 5,062,896. This patent relates to a polymer-solder composite paste with a powder of a eutectic metal alloy as a filler, said alloy having a melting point of less than 200 ° C and a weight of the total paste of about 85-93. Included at a concentration of wt%.

The paste composition of the above patent contains a thermoplastic polymer as a second component. The advantages of this patent are:
The presence of a thermoplastic polymer. The thermoplastic polymer contained in the paste of said patent makes the paste remeltable. Those skilled in the art know that thermoplastic polymers do not cure to form a three-dimensional network. Although the thermoplastic polymer in the patent is preferred to be poly (imidosiloxane), it is essentially non-crosslinkable and can therefore be remelted or redissolved.

The third component contained in the above patent is a volatile organic solvent having a boiling point higher than the melting point of the alloy powder and lower than the maximum reflow temperature of the composite paste composition.

Finally, the fourth essential ingredient contained in said patent is a temporary flux material, an aliphatic monocarboxylic acid, having a boiling point of about 140-200 ° C. However, aromatic monocarboxylic acids such as 2-methoxybenzoic acid can also be used. The content of this flux material is about 0.5 to 1.5% by weight.

Although the paste composition of the above patent may contain any component such as a surfactant, which is a significant advance in the art, it is a composite material of metal powder and polymer. This solution to the problems associated with remelting does not solve the other problems associated with prior art materials. That is, the problems associated with acidic fluids, which originate from the fourth indispensable component, the temporary flux material, and which have a deleterious corrosive effect on expensive electrical components electrically connected by paste, have not been solved.

Since the paste of the above patent contains a metal which is easily oxidized, as is apparent from the use of a metal having a melting point of less than 200 ° C., it must contain a flux component. Thus, the advances in the industry that the pastes of the patent make do not solve all of the problems associated with prior art conductive interconnect materials.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a new conductive paste which can be remelted and which does not contain a flux material that corrodes electrical components.

[0011]

A new conductive paste has been developed which solves the problems associated with prior art conductive compositions used to electrically connect conductive members. That is, the conductive paste of the present application not only allows the paste to be remelted, but also does not contain a flux material, so that the problems associated with acidic flux can be solved.

According to the present invention, a conductive paste is provided. The paste contains a thermoplastic polymer, a conductive metal powder, and an organic solvent system.

Further in accordance with the present invention, a conductive composite material is provided. The composite material contains at least 30% by volume of conductive metal powder, based on the total volume of the composite material.

Further in accordance with the present invention, there is provided a method of forming a circuit on a flexible substrate to form a flexible circuit.
According to this method, electric parts such as integrated circuit chips and surface mount devices are connected to the flexible substrate by the conductive paste according to the present invention. This paste is converted into the conductive composite material of the present invention by the action of heat.

Further in accordance with the present invention, a method of interconnecting multi-layer structures (also referred to as multichip module laminates) is taught. In this method, a multi-layer structure of a thermoplastic polymer, such as polyimide, is fused or via a pair of vias or through holes or blind holes from a pair of multi-layer structures fused by suitable heat and pressure using the conductive paste of the present application. Are electrically connected to each other.

Further in accordance with the present invention, a method of surface mounting integrated circuit (IC) chips in a leadframe is disclosed. According to this method, the conductive leads of a lead frame, or surface mount device, such as a capacitor or resistor, is electrically connected to a pad of a circuit board by a paste composition of the present invention that is converted to a conductive composite material by heating. Connected.

Finally, the present invention teaches a method of directly bonding an uninsulated integrated circuit chip to a circuit board. According to this method, the terminal I / of the bare integrated circuit chip is
Place it upside down so that the O-pad contacts the conductive pads on the circuit board surface. An effective amount of the paste of the present invention is placed between the I / O pad of the chip and the conductive pad of the circuit board. The paste is heated to convert it to a conductive composite material, forming a conductive path between the chip and the circuit board.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The conductive paste of the present invention is a composition containing three components. The first of these components is a thermoplastic polymer. Polymers selected from, for example, thermoplastic polymers having repeating structural units containing at least one atom or group selected from the group consisting of sulfur, oxygen, nitrogen, silicon, alkyl groups and phenyl groups. Good. The repeating structural unit of the thermoplastic polymer of the conductive paste may have two or more of the above atoms or groups.

The thermoplastic polymers are homopolymers, ie polymers in which a single monomer repeats, segmented copolymers, or segmented copolymers having at least three different homopolymers and their Any of the mixtures may be used. The segmented copolymers contemplated for the thermoplastic polymers of this invention contain at least two comonomers provided in the form of segments. A comonomer provided in the form of a segment is a co-monomer having a block of repeating monomeric units of a first monomer and adjacent repeating monomeric units of at least one different monomer. The length of these monomer units may be the same or different, forming a coalesce, and the length may vary from one to many monomers. The segmented copolymer of the present invention preferably has a soft repeating monomer unit composed of a non-polar unit and a hard repeating monomer unit composed of a polar unit.

Preferred homopolymers contemplated as thermoplastic polymers for the conductive pastes of this invention include polysulfones, polyolefins, and polyacrylates.

The segmented copolymers contemplated by this invention include poly (imide urea), poly (ether siloxane), poly (imido siloxane), poly (styrene butadiene), poly (styrene isoprene), poly (acrylonitrile butadiene). , Poly (ethylene vinyl acetate)
And copolymers such as polyurethane.

The preferred segmented copolymers described above are:
It is a thermoplastic elastomer. This polymer does not have the detrimental properties of thermoplastic polymers and elastomers, but combines the beneficial properties of both. That is, thermoplastic elastomers, unlike conventional elastomers, can remelt and change shape. Similarly, unlike conventional thermoplastic polymers, thermoplastic elastomers exhibit good elastic recovery upon stretching.

All thermoplastic polymers which can be used as components of the conductive paste have the requirement of having good thermal stability. To that end, the decomposition temperature of the thermoplastic polymer is preferably at least about 200 ° C. The decomposition temperature of the thermoplastic polymer is at least about 30.
More preferably, it is 0 ° C.

The second component of the conductive paste of the present invention is
It is a powder of a conductive metal. The conductive metal powder is a metal powder that does not contain oxides and has a melting point of at least about 200.
C. is preferred. By "free of oxides" is meant either that the metal does not form an oxide or that it does not act as an electrical insulator. Thus, gold, silver, tin, nickel, ruthenium, rhodium, palladium, platinum, and iridium are preferred for use as "oxide free" metals. The oxide-free metal includes an oxide-free metal element, an alloy of at least two kinds of oxide-free metal elements, or a single oxide-free metal element or at least two kinds of oxides. It is possible to use a surface oxide-free metal coated with an alloy of a metallic element that does not exist. By "powder" is meant a single particle having a diameter or major dimension of less than 50 μm, or an agglomerate of smaller particles.

The oxide-free metal, whether used alone or as an alloy, in pure form or as a coating, is preferably silver or gold.

Those skilled in the art will recognize that there is a need for a diffusion barrier layer to prevent certain oxide-free metals from diffusing into the core of susceptible metals. Ah For example, cobalt, preferably a cobalt alloy, and phosphorus are often added to a copper core prior to gold coating. This prevents the gold coating from diffusing into copper even at high temperatures.

This second component is less preferred than the oxide-free metals mentioned above, but may be, for example, an organic polymer or inorganic material core coated with an oxide-free metal.

In such embodiments with an organic polymeric material core, the organic polymer is preferably spherical particles of polystyrene latex.

In yet another embodiment with an inorganic material core, the inorganic material is an oxide such as silica, alumina, zirconia, titania, borate, titanate, silicate,
Solid powder of carbide, nitride, or other ceramic material.

The average particle size of the conductive metal powder is about 20 μm.
m or less. More preferably, the average particle size of the metal powder used in the conductive paste of the present application is about 10 μm or less. More preferably, the average particle size of the metal powder is about 5 μm or less.

The third component of the conductive paste of the present application is
Organic solvent systems having at least one polar organic solvent are preferred. The polar organic solvent used in the conductive paste of the present invention preferably has a boiling point of about 1 at atmospheric pressure.
It is in the range of 30 to 300 ° C. More preferably, the boiling point at atmospheric pressure is in the range of about 150 to 250 ° C.

The polar solvent satisfying the above criteria is, but is not limited to, esters, ethers, amides, lactones, or sulfones. Therefore, dimethyl adipate, esters such as ethyl benzoate, acetophenone, ethers such as 2-methoxyethyl ether, amides such as dimethylacetamide, lactones such as N-methylpyrrolidinone, sulfones such as dimethyl sulfoxide, Included within the range of polar solvents useful in the pastes of the present invention.

The paste of the present invention preferably contains at least one kind of polar organic solvent among the above-mentioned solvents, but it may contain a plurality of these solvents. That is, the solvent may be a mixture of a plurality of these solvents. In addition to one or more polar organic solvent, one containing one or more non-polar solvent may be contained.

In the preferred embodiment in which the non-polar organic solvent and at least one polar solvent are used in combination, the non-polar solvent is preferably a liquid hydrocarbon.
More preferably, liquid aromatic hydrocarbons are used. The preferred aromatic hydrocarbons used in the pastes of the invention as part of the polar solvent composition are xylene and trimethylbenzene.

Components such as corrosion inhibitors and surfactants may optionally be added to the conductive paste. But,
It should be emphasized that the conductive paste contains no flux material.

The second aspect of the present invention relates to a conductive composite material. The conductive composite material is composed of a metal containing no oxide. The oxide-free metal is preferably present in at least about 30% by volume, based on the total volume of the composite material. The metal component of the composite material has the characteristics of the above-mentioned conductive metal powder used in the conductive paste. The preferred embodiment of the conductive metal powder is the same as the preferred metal powder in the conductive paste described above.

More preferably, the oxide-free metal is present in at least about 40% by volume, based on the total volume of the composite material.

The second component of the conductive composite material is a thermoplastic polymer. The thermoplastic polymer used in this composite is the same as the thermoplastic polymer component of the conductive paste. The thermoplastic polymer of the composite material has the properties of the thermoplastic polymer of the conductive paste, including the preferred embodiments.

The conductive composite material of the present invention is formed by heating the conductive paste of the present invention. In order to improve or facilitate the adhesion of electric parts, the adhesion pressure is applied simultaneously with heating. Specifically, the conductive paste is injected between the conductive leads of two or more electric components. The temperature of the paste is brought above the boiling point of the solvent to evaporate the solvent from the paste. The pressure need not be atmospheric. A vacuum may be applied to lower the boiling point of the solvent.

In an alternative embodiment, dynamic gas exchange is used in the solvent removal step of the process of converting the conductive paste into a composite material. This method is a method well known to those skilled in the art, and is a method of removing the solvent by evaporation at a temperature below the boiling point of the solvent at atmospheric pressure. This step is usually carried out in a stream of nitrogen or other inert gas.

The method of forming the conductive interconnects is done by either of two bonding methods. In the first method,
After injecting the paste, pressure is applied at a temperature above the glass transition temperature of the thermoplastic polymer. In this first method,
The solvent evaporates and the thermoplastic polymer flows, forming a conductive bond. In the second method, the paste is first dried (ie the solvent is removed) at a temperature below the glass transition temperature of the thermoplastic polymer. Next, the temperature is raised above the glass transition temperature of the thermoplastic polymer to complete the conversion to a conductive composite material. As mentioned above, this method is time and temperature sensitive. Obviously, the higher the bonding temperature, ie the temperature at which the paste is exposed, the shorter the time required. Optimal adhesion conditions depend on the specific structure to be formed and the glass transition temperature of the thermoplastic polymer.

The conductive composite material may contain one or more optional components. These optional ingredients include, for example, corrosion inhibitors, surfactants and the like. The conductive composite material formed of the conductive paste of the present invention does not contain a flux agent like the paste.

The criteria for selecting the formulation depend on (i) the conductivity of the polymer / metal composite, (ii) the hydrodynamic properties of the polymer / metal / solvent paste, and (iii) the intended application. And is based on a balance of polymer wetting and adhesive properties to the filler metal or other substrate.

Regarding conductivity, the ionic impurities that act as "electron traps" during the metal / insulator / metal tunneling effect are linear currents (I) in the current range defined by the intended application. It must be low enough to maintain the voltage drop (V) characteristic. Also, the conductivity (σ) vs. temperature (T) behaves like a metal, rather than that seen in a disordered system where the conductivity decreases with increasing temperature, ie log (σ) ~ T. You need to follow the 1/4 rule. Finally, the resistivity of liquid helium at temperature should be as low as possible. For good adhesion, it is preferred that the polymerisation pair wets the metal filler and the substrate material specified in the intended application and the Young's modulus of the polymer is above 0.1 GPa at 25 ° C. . The paste should have a non-Newtonian viscosity in the range of about 3000-5000 poise with respect to hydrodynamic behavior, an initial normal stress differential as low as possible, and a low elastic recoil. In addition, the paste should have a reduced viscosity when subjected to shear, as opposed to a non-Newtonian fluid, which has the usual viscoelastic properties and is stable in viscosity.

Another aspect of the invention relates to a method for use in the manufacture of electrical components and devices by converting the novel conductive paste into the composite material of the invention. The method involves bonding at least one flexible electrical component substrate to an electrical component. Such bonding, using the conductive paste of the present invention, is done to assemble flexible substrates to form flexible or "flex" circuits.

In this method, the conductive paste of the present invention is injected between the conductive surface of the flexible substrate on which the circuit is formed and the conductive surface of the electric component. After injecting the paste in this manner, heat and pressure are applied for a time sufficient to convert the conductive paste into a conductive composite material and form a bond. Preferably, the paste is at least about 0.3
It is pressurized at a pressure of 5 kg / cm 2 and heated to a temperature higher than the glass transition temperature of the polymer. In the obtained product, an electrical connection is formed between the flexible substrate and the electric component, and the flexible circuit is completed.

A second application of the conductive paste and composite material of the present invention is in the process of making so-called "via-via" interconnections of multilayer structures. This method is shown in FIG. Layer 10 has vias 8 with copper plating 6. The layer 10 includes a metal wire 4 in the X direction and a metal wire 5 in the Y direction.
Contains. Layer 10 is a ground plane 3 surrounded by a dielectric layer 2.
Having. Layer 10 also includes an adhesive surface 7.

Layer 10 is electrically interconnected to second layer 50 by the conductive paste of the present invention. Specifically, the mass 12 of the conductive paste is poured into the via 8 so as to rise from the top and the bottom. These aspects are
It includes an adhesive dielectric 7. In order to electrically connect layer 10 to layer 50, one or more vias are similarly filled with a mass of conductive paste, then after the drying step described above, the layers are aligned, Pressing at a suitable pressure and a temperature above the glass transition temperature of the polymer so that the paste in the vias of the layer melts to form the conductive composite material.

Another important utility of the conductive pastes and composites of the present invention is in the method of surface mounting. The use of this conductive paste and composite material is shown in FIG.
In FIG. 2, an insulating circuit board 2 made of organic polymer, ceramic, etc.
0 has a plurality of terminal points called pads in the art. This is indicated by pads 22 and 24 in FIG. Pads 22 and 24 are electrically connected to integrated circuit chips in lead frame 25 by conductor tubes 26 and 27, thereby electrically connecting substrate 20 and integrated circuit chip 25. This connection is made permanent by the conductive paste of the present invention. As shown in FIG.
The paste masses 21 and 23 injected between each lead to pads 27 and 27 and pads 22 and 24 are heated to a temperature above the glass transition temperature of the polymer and subjected to sufficient loading,
Preferably at least tip 25 and conductor tubes 26 and 2
When subjected to a load equal to the sum of its weight and 7, it forms the composite material of the present invention.

Yet another application of the conductive paste and composite material of the present invention is in a method of obtaining a "flip chip" connection, as described in US Pat. No. 4,434,434. Such connections are a major advance in computer technology. The "flip chip" connection allows the integrated circuit chip to be directly attached to the circuit board by means other than wiring. If you do wiring, it will take a lot of work,
Takes up space and is therefore expensive and time consuming,
The use of conductive pastes in the manufacture of computers and other complex devices represents a significant advance.

In the method of the present invention, flip chip bonding can be performed by utilizing the conductive paste of the present invention. This method will be described with reference to FIG. 3, which shows a schematic diagram of this connection. Chip 30 is "flip" or turned upside down to align pads 34 on its surface with pads 36 on circuit board 32 (sometimes referred to as the substrate). A small amount of conductive paste 38 is injected between the pad 34 and the pad 36 so that an electrical connection can be obtained. Thereafter, the entire apparatus is heated, preferably about 0.3.
Pressurizing to 5 kg / cm 2 transforms the paste into the conductive composite material of the invention, making this electrical connection permanent.

Alternatively, in a flip chip process, the paste may be applied to substrate pads, chip pads, or both. Then dry the paste,
The two surfaces are aligned, pressed and heated above the glass transition temperature of the thermoplastic polymer to rapidly obtain the desired electrically connected device in a substantially defect free manner. .

The above application examples highlight the technological advancements associated with the pastes and composites of the present invention.
By the combination of unique components that make up the paste composition,
The electrical and electronic components can be easily converted into a permanent composite material that electrically connects them under relatively mild temperature and pressure conditions without damaging the electrical and electronic components. Moreover, despite the "permanent" formation of the composite, these connections are above the glass transition temperature of the thermoplastic component of the composition without damaging the parts connected by the composite. It can be easily disconnected by giving.

The following examples illustrate the scope of the invention. These examples are for illustrative purposes only, and the invention is not limited to these examples.

[0055]

【Example】

Example 1 28% by weight of poly (imidosiloxane), based on the total weight of the solution, was dissolved in acetophenone to form a solution of poly (imidosiloxane). To this solution was added flake of metallic silver having a particle size of about 1 to 5 μm in length and width and about 1 μm in thickness. The amount of silver particles was 87% by weight based on the total weight of silver and poly (imidosiloxane). This 87 wt% concentration was calculated independently of the weight of the acetophenone solvent.

A dispersion of silver particles in an acetophenone solution of the obtained poly (imidosiloxane) was treated with Mueller (Mu
A paste was produced by mixing with a eller) ™ high shear mixer with high shear.

The above paste composition was applied to the flip-chip connection method (FCA), and the center distance was set to 200 μm on a substrate coated with gold, and the diameter was 100 μm.
m, and a height of about 100 μm. The array of features was 11x11. The resulting circular array was adhered to another substrate coated with gold at an adhesion load of about 1.1 kg and a temperature of 340 ° C. The resistance of the entire structure is ≤1μ
Ω · cm 2 . The adhesive strength of the 11 × 11 array was about 210 kg / cm 2 .

Example 2 In the same manner as in Example 1 except that the solvent was used, 28% by weight of poly (imidosiloxane) was added to N-methylpyrrolidone (NM).
The solution dissolved in P) was mixed with gold particles having a particle size of 1-5 μm. The amount of gold particles added to the poly (imidosiloxane) solution was such that the gold particles were 92% by weight, based on the total weight of gold and poly (imidosiloxane). This ratio was independent of the weight of NMP solvent.

As in Example 1, the gold dispersion in the NMP solution of poly (imidosiloxane) was treated with Mueller.
ler) ™ high shear mixer
A paste was produced.

This paste was treated with FCA in the same manner as in Example 1.
Used for The adhesive strength at an adhesive load of about 1.25 kg was about 225 kg / cm 2 .

Example 3 A mixture of 13% by weight of poly (imidosiloxane), 68% by weight of flake of silver metal having a particle size of about 3 to 10 μm in length and width and about 1 μm in thickness, and 19% by weight of acetophenone was added. Mixed with a shear mixer to produce a paste. As an example of surface mounting as shown in FIG. 2, this paste was adhered to Cu pads from which surface oxide was removed on an epoxy substrate. The paste consists of 28 1.65 mm 2 of 1.27 mm pitch with 14 pads arranged in two rows.
It was deposited on the individual pattern. 28-pin VSOP
(Ultra small outline package) was attached to the uncured paste. After the mounting part is dry, 220
Cured at 0 ° C for 10 minutes. The adhesive strength of the component to the circuit board was about 0.27 kg per lead.

[Brief description of drawings]

1 uses the pastes and composites of the invention,
FIG. 6 is a cross-sectional view illustrating making a via-via interconnection between two layers including a circuit.

FIG. 2: Using the pastes and composites of the invention,
5 is a schematic view showing surface mounting of integrated circuit chips in a lead frame on a circuit board.

FIG. 3: Using the pastes and composites of the invention,
A "flip chip" between the integrated circuit chip and the circuit board
3 is a schematic diagram showing making a connection and making an adhesive and electrical connection between two parts.

[Explanation of symbols]

 2 Dielectric layer 3 Ground plane 4 Metal wire in X direction 5 Metal wire in Y direction 6 Copper plating 7 Bonding surface 8 Vias 10, 50 Layer 12 Conductive paste 20 Circuit board substrate 21, 23 Conductive paste 22, 24 Pad 25 Lead Frame 26, 27 Conductor tube 30 Chip 32 Circuit board 34, 36 Pad 38 Conductive paste

[Procedure amendment]

[Submission date] March 26, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Judith Marie Roldan 15 Willow Street, Osining, New York, USA (72) Inventor Michael Anthony Gaines Vestal, NY, USA 340 Horse Show Lane ( 72) Inventor Richard Benton Boss, 304 Camille Court, Pifkerville, Texas, USA (72) Inventor Stefan Paul Ostrander, 6th, Stephan Lane, Scottia, New York, USA (72) Inventor, Emmanuel Eye Cooper 2575 Apt, Parisades Avenue, Riverdall, NY, USA 8 Ray (72) Inventor Carlos J. Sambusset Croton-on-Hudson, NY, USA, 4 Sashi Drive

Claims (31)

[Claims]
1. A conductive paste containing a thermoplastic polymer, a conductive metal powder, and an organic solvent system.
2. A thermoplastic polymer having a repeating structural unit comprising at least one atom or group selected from the group consisting of sulfur, oxygen, nitrogen, silicon, alkyl groups and phenyl groups. Paste according to claim 1, characterized in that it is selected from molecules.
3. The thermoplastic polymer is selected from the group consisting of homopolymers, segmented copolymers, or segmented copolymers having at least 3 different homopolymers and mixtures thereof. The paste according to claim 1.
4. The paste according to claim 3, wherein the segment length in the segmented copolymer varies from one monomer unit to a number of units.
5. The thermoplastic polymer is a homopolymer selected from the group consisting of polysulfones, polyolefins, and polyacrylates.
The paste according to claim 3.
6. The thermoplastic polymer is poly (imide urea), poly (ether siloxane), poly (imide siloxane), poly (styrene butadiene), poly (styrene isoprene), poly (acrylonitrile butadiene), poly (ethylene). Paste according to claim 3, characterized in that it is a segmented copolymer selected from the group consisting of vinyl acetate) and polyurethane.
7. The conductive metal powder comprises a metal element containing no oxide, an alloy of at least two metal elements containing no oxide, a solid coated with a metal element containing no oxide, and at least two kinds. The paste according to claim 1, characterized in that it is selected from the group consisting of solids coated with an alloy of metal oxides which does not contain the oxide of.
8. The conductive metal powder is a metal selected from the group consisting of gold, silver, tin, nickel, ruthenium, rhodium, palladium, platinum, iridium, and alloys of two or more of these metals. The paste according to claim 7, characterized in that
9. The conductive metal powder is coated with a metal selected from the group consisting of gold, silver, tin, nickel, ruthenium, rhodium, palladium, platinum, iridium, and alloys of two or more of these metals. The paste according to claim 7, wherein the paste is a solid.
10. Paste according to claim 9, characterized in that the solid is selected from the group consisting of organic polymers, surface oxide-free metals, and inorganic materials.
11. The organic polymer is spherical particles of polystyrene latex, and the inorganic material is silica, alumina, titania, zirconia, borate, titanate, silicate, carbide, and nitride. Paste according to claim 10, characterized in that it is selected from the group consisting of:
12. Paste according to claim 1, characterized in that the organic solvent system comprises at least one polar organic solvent.
13. Paste according to claim 12, characterized in that the polar organic solvent is selected from the group consisting of esters, ethers, amides, lactones and sulfones.
14. The polar organic solvent is selected from the group consisting of dimethyl adipate, ethyl benzoate, acetophenone, 2-methoxyethyl ether, dimethylacetamide, N-methylpyrrolidinone, dimethylsulfoxide, and mixtures thereof. Characterized by,
The paste according to claim 13.
15. The paste according to claim 12, comprising a second solvent selected from the group consisting of a second polar organic solvent, a non-polar solvent, and mixtures thereof.
16. Paste according to claim 15, characterized in that the non-polar solvent is selected from the group consisting of xylene and trimethylbenzene.
17. A conductive composite material comprising a conductive metal powder and a thermoplastic polymer, wherein the amount of the conductive metal powder is at least about 30 volumes with respect to the total volume of the metal powder and the thermoplastic material. %, The conductive composite material.
18. The conductive metal powder is a metal element containing no oxide, an alloy of at least two metal elements containing no oxide, a solid coated with a metal element containing no oxide, and at least two kinds. 2. The oxide selected from the group consisting of solids coated with an alloy of metallic elements free of oxides according to claim 1.
7. The composite material according to 7.
19. The conductive metal powder is gold, silver, tin,
Nickel, ruthenium, rhodium, palladium, platinum,
The composite material according to claim 18, which is a metal selected from the group consisting of iridium and alloys of two or more kinds of these metals.
20. The conductive metal powder is gold, silver, tin,
Nickel, ruthenium, rhodium, palladium, platinum,
20. A composite material according to claim 19, characterized in that it is a solid coated with a metal selected from the group consisting of iridium and alloys of two or more of these metals.
21. Composite material according to claim 20, characterized in that the solid is selected from the group consisting of organic polymers, metals without surface oxides, and inorganic materials.
22. The thermoplastic polymer comprises sulfur, oxygen,
18. A thermoplastic polymer having a repeating structural unit containing at least one atom or group selected from the group consisting of nitrogen, silicon, alkyl groups and phenyl groups. Composite material.
23. The thermoplastic polymer is a homopolymer,
23. Composite material according to claim 22, characterized in that it is selected from the group consisting of segmented copolymers, or segmented copolymers having at least 3 different homopolymers and mixtures thereof.
24. The composite material according to claim 23, wherein the segment length in the segmented copolymer varies from one monomer unit to many units.
25. The thermoplastic polymer is polysulfone,
25. The composite material according to claim 24, characterized in that it is a homopolymer selected from the group consisting of polyolefins, polyacrylates, and mixtures thereof.
26. The thermoplastic polymer is poly (imide urea), poly (ether siloxane), poly (imide siloxane), poly (styrene butadiene), poly (styrene isoprene), poly (acrylonitrile butadiene), poly (ethylene). 26. A segmented copolymer selected from the group consisting of vinyl acetate), polyurethane, and mixtures thereof.
Paste described in.
27. A glass of a polymer contained in the conductive paste after contacting the electrical component and a flexible substrate having a circuit formed thereon with the conductive paste according to claim 1. A method of manufacturing a flexible circuit including the step of heating to a temperature above the transition temperature.
28. A method of electrically connecting a multi-layer structure having one or more penetrating vias, the method comprising placing the conductive paste of claim 1 in the vias and heating in air or under vacuum. Removing the solvent, then aligning the vias in adjacent layers, and heating the assembly to at least about 150 ° C.
29. Electrically contacting the leads of the lead frame with corresponding pads on the substrate of the circuit board and depositing the conductive paste of claim 1 on the pads.
A method of surface mounting comprising heating the assembly to a temperature above the glass transition temperature of a polymer contained in the conductive paste.
30. A method of connecting a chip of an integrated circuit to a circuit board, wherein the conductive paste of claim 1 is deposited on the pads of the chip, the circuit board, or both to form a chip of the chip. Aligning the pad with the pad of the circuit board, and heating the assembly to a temperature above the glass transition temperature of the polymer contained in the conductive paste.
31. The method of claim 30, further comprising the step of heating the paste to a temperature lower than the glass transition temperature of the polymer to dry the paste before the aligning step. Method.
JP08010295A 1996-01-24 1996-01-24 Conductive paste Expired - Fee Related JP3111010B2 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6512183B2 (en) 2000-10-10 2003-01-28 Matsushita Electric Industrial Co., Ltd. Electronic component mounted member and repair method thereof
WO2018181625A1 (en) * 2017-03-31 2018-10-04 田中貴金属工業株式会社 Electrically conductive adhesive composition

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6512183B2 (en) 2000-10-10 2003-01-28 Matsushita Electric Industrial Co., Ltd. Electronic component mounted member and repair method thereof
WO2018181625A1 (en) * 2017-03-31 2018-10-04 田中貴金属工業株式会社 Electrically conductive adhesive composition

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