JP2004158396A - Conductor connection method and conductor connection structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductor connection method and a conductor connection structure with improving reliability of connection by preventing the generation of oxide film on an electrode to be pressed for connection contact, and stopping the growth of the oxide film. <P>SOLUTION: As for the conductor connection method and the conductor connection structure, a reducing material or an antioxidant is adhered to either or both of electrodes of micro electrodes to be pressed for connection contact, and the electrodes are made of plated particles having resin core, and the electrodes are fixed by an adhesive agent. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for electrically connecting fine electrodes and a conductive connection structure obtained by the method.
[0002]
[Prior art]
In electronic products such as liquid crystal displays, personal computers, and mobile communication devices, opposing fine electrodes are connected, such as electrically connecting small components such as semiconductor elements to substrates, or electrically connecting substrates. . The fine electrodes are connected by using a metal bump or the like with a solder or a conductive paste, or by directly pressing the metal bump or the like.
[0003]
In the method of connecting opposing fine electrodes, contact-type conductive connection methods have been increasing because they can be connected at low temperature and low pressure and can be connected at low cost without damaging components. For example, there is a method of connecting the metal bump electrodes by directly pressing them via a sheet-like adhesive. However, the contact-type conductive connection method has a problem in that the adhesive force is hardly maintained in a high-temperature and high-humidity environment and connection reliability is extremely low as compared with alloy bonding such as solder.
[0004]
As a method of solving such a problem, there is a method of enclosing the entire part in a sealing resin or firmly bonding with an adhesive containing conductive fine particles. For example, JP-A-63-231889 and JP-A-4-259766 can be mentioned. Further, the connection reliability is further improved by connecting the electrodes by sandwiching the conductive fine particles between the electrodes facing each other, or connecting the electrodes by sandwiching the conductive paste between the electrodes with a conductive paste solidified between the electrodes. There are ways.
[0005]
However, although a certain effect is obtained, the reliability cannot be remarkably improved. The present inventors have found that the greatest cause of the decrease in connection reliability under a high-temperature and high-humidity environment is that a metal oxide film is formed on the surface of the contacting electrode. Usually, a thin metal oxide film exists on the electrode surface, and it was thought that the oxide film was broken by the pressure when connecting the electrodes, and it was thought that the oxide film would be conductive. It has been found that the connection reliability decreases due to the growth of the connection. It has also been found that this phenomenon occurs even if the electrode surface is gold.
[0006]
[Problems to be solved by the invention]
In view of the above, an object of the present invention is to provide a conductive connection structure having high connection reliability by providing a conductive connection method that does not generate or grow an oxide film present on an electrode surface.
[Means for Solving the Problems]
[0007]
In the present invention, a reducing agent or an antioxidant is attached to one or both of the fine electrodes to be pressed and connected. Further, at least one of the electrodes contains a resin component, and the electrodes are plated particles having a resin core. Further, at least one electrode surface is made of aluminum. A conductive connection structure and a conductive connection structure in which an electrode is used to fix the conductive connection structure formed using the above-described connection method and an electrode.
[0008]
In the conductive connection method of the present invention, a reducing agent or an antioxidant is attached to one or both of the fine electrodes to be pressed and connected.
[0009]
Examples of the reducing agent or antioxidant used in the present invention include phenolic antioxidants; 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole (BHA), bisphenol antioxidants; 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), high-molecular-weight phenolic antioxidant; 1,1,3- Tris (2-) methyl-4-hydroxy-5-t-butylphenyl) butane, tocopherol, sulfur antioxidant; dilauryl 3,3'-thiodipropionate, phosphorus antioxidant; triphenyl phosphite, aroma Aromatic amines: diphenylamine, phenylenediamine derivatives, phosphites; triphenyl phosphite, thiourea dioxide, diethylhydrogen Shiruamin, although quinones such as hydroxy quinone may be mentioned, may be a mixture thereof or inclusions, there is no particular limitation as long as there is a reduction action and antioxidant action.
[0010]
It is preferable that at least one of the fine electrodes is a resin containing conductive fine particles. If both electrodes are metal electrodes, there is a possibility that a gap is formed between the electrodes due to a small elastic repulsion at the time of contact, causing a conduction failure. However, a gap is hard to be formed because the electrode material containing resin has elasticity of the electrodes. The electrode that is a resin containing conductive fine particles is not particularly limited, and examples thereof include an electrode material obtained by solidifying a conductive paste and performing metal plating. Also, an electrode material made of resin-plated metal or the like is preferable since a gap is not easily formed because the electrode has elasticity. In particular, when the metal fine particles are sandwiched between opposing electrodes, the resin fine particles can be used as a gap adjusting material for connecting the opposing electrodes while being an electrode material.
[0011]
In addition, from the viewpoint of connecting the fine electrodes, the average particle diameter of the metal fine-plated resin fine particles is preferably 15 to 300 μm, and more preferably 30 to 150 μm.
[0012]
In addition, the aspect ratio of the metal-plated resin fine particles is preferably less than 1.2, more preferably less than 1.05, from the viewpoint of keeping the gap uniform. Here, the aspect ratio is a value obtained by dividing the average major axis by the average minor axis.
[0013]
The CV value of the metal fine-plated resin fine particles is preferably 5% or less, more preferably 1% or less. If the CV value exceeds 5%, it becomes difficult to keep the gap uniform. The CV value is represented by (σ / Dn) × 100% (σ represents the standard deviation of the particle diameter, and Dn represents the number average particle diameter).
[0014]
In addition, as resin fine particles, for example, phenol resin, amino resin, acrylic resin, ethylene-vinyl acetate resin, styrene-butadiene block copolymer, polyester resin, urea resin, melamine resin, alkyd resin, polyimide resin, urethane resin, Examples include particles made of a thermoplastic resin such as an epoxy resin, a curable resin such as a thermosetting resin or a photocurable resin, a crosslinked resin, and an organic-inorganic hybrid polymer. Among these, the fine particles are preferably a crosslinked resin because of their excellent heat resistance. In addition, the resin fine particles may include a filler as needed.
[0015]
When the electrodes are bonded, they may be bonded with a paste adhesive or a sheet adhesive. For example, thermoplastic resins such as phenolic resins, amino resins, acrylic resins, ethylene-vinyl acetate resins, styrene-butadiene block copolymers, polyester resins, urea resins, melamine resins, alkyd resins, polyimide resins, urethane resins, and epoxy resins And an adhesive using a thermosetting resin, a curable resin such as a photocurable resin, a crosslinked resin, an organic-inorganic hybrid polymer, or the like. Among these, an adhesive using an epoxy resin is particularly preferable because it has few impurities and has characteristics suitable for electrode connection. Note that an adhesive containing not only an uncured epoxy resin but also a semi-cured epoxy resin may be used. Further, the adhesive may include a reinforcing material such as glass fiber or alumina particles as necessary.
Above all, an adhesive using a thermosetting resin is preferable because a strong adhesive force can be obtained by pressing while heating, and connection reliability is high.
[0016]
The application of the conductive connection method of the present invention is not particularly limited. For example, in electronic products such as a liquid crystal display, a personal computer, and a portable communication device, a connection between a small component such as a semiconductor element and a substrate, a connection between substrates, and a connection between substrates. It is suitable for connecting fine electrode terminals.
[0017]
More specifically, for example, an active component such as a semiconductor such as an IC or an LSI; a passive component such as a capacitor or a crystal oscillator; and a connection between a bare chip or the like and a substrate. In particular, the conductive connection method of the present invention is suitable as a method for connecting bare chips or between a bare chip and a substrate.
[0018]
The shape of the electrode is not particularly limited, and examples thereof include a stripe shape, a dot shape, and an arbitrary shape. Examples of the material of the electrode include gold, silver, copper, nickel, palladium, carbon, aluminum, and ITO. Gold may be further coated on copper, nickel, etc. to reduce contact resistance. The thickness of the electrode is preferably 0.1 to 300 μm. The width of the electrode is preferably 1 to 500 μm.
[0019]
Aluminum electrodes are usually used for electrodes such as IC chips for various reasons. However, since aluminum electrodes are oxidized quickly, the connection method of the present invention that gives a reducing action to the electrodes requires that at least one electrode surface be made of aluminum. It is particularly preferred in some cases. Furthermore, when the electrodes are brought into contact with each other and connected, it is necessary to always press the electrodes with a certain force or more, and therefore it is preferable to bond and fix the electrodes.
[0020]
In the conductive connection method of the present invention, as a method of attaching a reducing agent or an antioxidant to an electrode, for example, a method of attaching a small amount directly to the electrode using a syringe or the like or an electrode of a substrate or a component having an electrode formed on the surface. There is a method in which a perforated film is placed at a position and attached with a squeegee. Further, a method of attaching the solution or the dispersion liquid by an ink jet method or printing may be used. It is excellent in that a small amount can be uniformly attached.
[0021]
(Example)
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
(Example 1)
Gold was further electroplated to 1.3 μm on the 0.2 μm nickel-plated resin fine particles. The obtained particles were classified to obtain metal-coated fine particles having an average particle diameter of 100 μm, an aspect ratio of 1.03, a CV value of 1%, a recovery rate of 60%, and a resistance value of 0.01Ω. In addition, 160 holes were made in a thermosetting epoxy resin tape having a thickness of 80 μm at a pitch of about 200 μm so as to match the electrode position of the IC chip. The hole was formed into a tapered hole having a front surface of 130 μm and a back surface of 80 μm by using a CO2 laser. In addition, a hole having a CV value of 2% and an aspect ratio of 1.04 was formed. Metal-coated fine particles were arranged in the holes and embedded in the tape to obtain a conductive connection tape. The electrode position of the circuit board ("FR-4") on which the electrode pattern was drawn and the position of the metal-coated fine particles of the conductive connection tape were aligned and lightly pressed to temporarily fix them.
[0022]
An ethanol solution of butylated hydroxyanisole is applied to an aluminum electrode on an electrode of an IC test chip (10 mm square, 0.1 mm square electrode, daisy chain wiring) and dried. Were pressed together while heating at a pressure of 4 kg per 1 m ² , and the epoxy resin sheet was cured to make conductive connection.
[0023]
The connection structure thus obtained has stable conduction with all electrodes, there is no leakage between adjacent electrodes, and the resistance of the daisy-chain-shaped wiring portion is as low as about 30Ω even when wiring resistance is inserted. It was resistance. In addition, 1000 cycles of the cooling / heating cycle test (−40 ° C. to 125 ° C., 30 minutes each) and 500 hours (85 ° C., 85%) of the high temperature and high humidity test were performed. As a result, there was no leakage between the adjacent electrodes, and the resistance of the daisy chain wiring portion was hardly changed, and high connection reliability was obtained.
[0024]
(Example 2)
A silver paste was printed on electrodes of a circuit board ("FR-4") and heated to cure the paste. Gold plating was further performed on the cured paste. On the other hand, tocopherol was attached to the electrode of the IC test chip using a syringe. Next, the electrodes were positioned so as to face each other via a thermosetting epoxy resin sheet, and were pressed while heating, and the electrodes were contacted and connected while embedding the electrodes in the epoxy resin. In the obtained connection structure, stable conduction was maintained at all the electrodes, there was no leakage at the adjacent electrodes, and the resistance of the daisy chain wiring portion was as low as about 30Ω even when the wiring resistance was inserted. Was. In addition, 1000 cycles of the cooling / heating cycle test (−40 ° C. to 125 ° C., 30 minutes each) and 500 hours of the high temperature and high humidity test (85 ° C., 85%) were performed. And the resistance of the daisy-chain-shaped resistance portion increased slightly, but was small, and high connection reliability was obtained.
[0025]
(Example 3)
Diphenylamine was deposited on the electrodes of the circuit board ("FR-4"). This board and the stud bump of the IC test chip which connected the gold wire to the aluminum electrode faced each other through the thermosetting epoxy resin tape, pressed and heated, and brought the electrodes into contact with each other while embedding the electrode in the epoxy resin. Connected. In the obtained connection structure, stable conduction was maintained at all the electrodes, there was no leakage at adjacent electrodes, and the resistance of the daisy chain wiring portion was as low as about 30Ω including the wiring resistance. Although a high-temperature and high-humidity test was performed for 500 hours (85 ° C., 85%), stable conduction was maintained at all the electrodes, there was no leakage at the adjacent electrodes, and although the resistance of the daisy chain wiring portion was slightly increased. Hardly changed. When a cooling / heating cycle test was performed for 1000 cycles (−40 ° C. to 125 ° C., 30 minutes each), conduction failure occurred at 800 cycles, but no conduction failure occurred at −25 ° C. to 110 ° C. even at 1000 cycles. It was determined that use in the liquid crystal field and the like was sufficient for practical use.
[0026]
(Comparative Example 1)
A conductive connection structure was prepared in the same manner as in Example 1 except that an IC test chip not coated with butylated hydroxyanisole was used for the aluminum electrode.
[0027]
The obtained conductive connection structure maintained stable continuity at all electrodes and did not leak at adjacent electrodes, but the resistance of the daisy chain wiring portion was about 40Ω when wiring resistance was added, and a high resistance value was obtained. became. In addition, 1000 cycles of the cooling / heating cycle test (−40 ° C. to 125 ° C., 30 minutes each) and 500 hours of the high temperature and high humidity testing (85 ° C., 85%) were performed. In the cycle, the resistance value was 1.5 times or more as compared with the initial value, and in the high-temperature and high-humidity test, the resistance value was 1.5 times or more as compared with the initial value in 200 hours.
[0028]
(Comparative Example 2)
A conductive connection structure was prepared in the same manner as in Example 2 except that tocopherol was not attached to the electrode. Although stable conduction was maintained at all the electrodes and there was no leakage at the adjacent electrodes, the resistance of the daisy-chain wiring portion was about 40Ω when the wiring resistance was added, and the resistance value was high. In addition, 1000 cycles of the cooling / heating cycle test (−40 ° C. to 125 ° C., 30 minutes each) and 500 hours of the high temperature and high humidity testing (85 ° C., 85%) were performed. In the cycle, the resistance was 1.5 times or more the initial resistance, and in the high temperature and high humidity test, it was 1.5 times or more the initial resistance in 50 hours.
[0029]
(Comparative Example 3)
A conductive connection structure was prepared in the same manner except that diphenylamine was not attached on the electrodes of the circuit board ("FR-4"). Although stable conduction was maintained at all the electrodes and there was no leakage at the adjacent electrodes, the resistance in the daisy chain was as low as about 30Ω including the wiring resistance. In addition, 1000 cycles of the cooling / heating cycle test (−40 ° C. to 125 ° C., 30 minutes each) and 500 hours of the high temperature and high humidity testing (85 ° C., 85%) were performed. In the high-temperature and high-humidity test, conduction failure occurred in 100 hours. Regarding the thermal cycle test, the test was performed under the condition of −25 ° C. to 110 ° C., but conduction failure occurred in 500 cycles.
[0030]
【The invention's effect】
A highly reliable conductive connection structure can be obtained by the conductive connection method of the present invention.
Further, when at least one of the fine electrodes is made of a resin containing conductive fine particles, elastic repulsion at the time of contact can prevent conduction failure due to a small gap change.

Claims (6)

A conductive connection method characterized in that one or both of the fine electrodes is pressed and connected to a fine electrode on which a reducing material or an antioxidant has been previously attached. 2. The conductive connection method according to claim 1, wherein at least one of the electrodes is a resin containing conductive fine particles. 2. The conductive connection method according to claim 1, wherein at least one of the electrodes is made of plated resin fine particles. 4. The conductive connection method according to claim 1, wherein at least one electrode surface is made of aluminum. A conductive connection structure connected using the method according to claim 1. The conductive connection structure according to claim 5, wherein the connected electrodes are bonded to each other.