JPH11121072A - Connecting member and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix electronic components to a circuit board, or circuits boards to each other by adhesive and electrically connect both electrodes to each other by forming a single-layer conductive grain densely dispersed part arranged on a photo-curing resin layer formed on an exfoliative base material. SOLUTION: At first, a photo-curing resin layer is formed on an exfoliative base material 1. Secondly, a light 5 is irradiated on the photo-curing resin layer 2 via a mask 3 having a through hole 4 in its necessary part so that a hard adhesive part 6 and a weak adhesive part 7 are formed on the surface of the resin layer 2. Thirdly, conductive grains 8 are dispersed on the photo-curing resin so that a conductive grain densely dispersed part for sticking the conductive grains 8 on the hard adhesive part 6 is formed. Forthly, an adhesive film 9 is formed on, at least, the weak adhesive part 7 of the photo-curing resin layer 2 as a connecting member of the photo-curing resin layer 2 as necessary. Then, the densely dispersed region of the conductive grains 8 is pressurized between rolls or parallel plates while being heated as necessary so that its whole body or one part can be embedded in the hard adhesive part 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting member for fixing an electronic component to a circuit board, or for bonding and fixing the circuit boards to each other, and for electrically connecting both electrodes, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, as electronic components have become smaller and thinner, circuits used in these components have become higher in density and higher in definition. Since it is difficult to cope with the problem, recently, anisotropic conductive adhesives and film-like materials (hereinafter referred to as connection members) having excellent resolution have been frequently used. The connecting member is made of an adhesive containing a predetermined amount of conductive particles, and the connecting member is provided between the electronic component and the electrode or the circuit, and a pressurizing or heating pressurizing means is provided. The electrodes are electrically connected to each other, and the electrodes formed adjacent to the electrodes are provided with insulating properties so that the electronic component and the circuit are bonded and fixed. The basic idea for increasing the resolution of the connection member is to make the particle size of the conductive particles smaller than the insulating portion between the adjacent electrodes, thereby ensuring insulation between adjacent electrodes, and at the same time, containing conductive particles. By setting the amount to such a degree that the particles do not come into contact with each other, the conductivity at the connection portion can be reliably obtained. However, if the particle size of the conductive particles is reduced, the particles will undergo secondary aggregation due to a remarkable increase in the surface area of the particles, making it impossible to maintain insulation between adjacent electrodes. Since the number of the above-mentioned conductive particles also decreases, the number of contact points becomes insufficient, and conduction at the connection electrode cannot be obtained. Therefore, it has been extremely difficult to increase the resolution of the connection member while maintaining long-term connection reliability. As a connecting member which enables connection of such fine electrodes and circuits and has high connection reliability, we previously disclosed in Japanese Patent Application No. Hei 9-108471 by spraying conductive particles on the surface of an adhesive film. A connecting member in which conductive particles are unevenly distributed on the surface layer was proposed. According to this, a dot-like electrode such as a semiconductor chip, a TAB or the like can be prevented by preventing the secondary aggregation of the conductive particles, making the conductive particle-containing layer extremely thin and removing the conductive foreign matter in the adhesive. It is possible to connect a line-shaped fine electrode having a large number of insulated parallel electrodes such as an FPC.

[0003]

The above method is excellent as a method for easily obtaining a high-precision connection member.
Due to the method of spraying conductive particles and fixing the particles on the entire surface of the adhesive film by the surface adhesiveness, the distribution of the conductive particles is uneven when viewed microscopically, making industrial mass production difficult. There were drawbacks. The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to provide a connection member having a dense area of conductive particles in a main part and an industrial production method thereof.

[0004]

A first object of the present invention is to provide a connecting member in which a conductive particle dense portion arranged as a single layer is formed on the surface of a photocurable resin layer formed on a peelable substrate. About. A second aspect of the present invention has a conductive particle dense portion arranged in a single layer on a surface of a photocurable resin layer formed on a peelable substrate, and adheres to at least a part of the photocurable resin layer. The present invention relates to a connection member formed with a film. 3 of the present invention
Relates to a method for manufacturing a connection member comprising the following steps. (1) Step of forming a photo-curable resin layer on a peelable substrate (2) Irradiation of light to the photo-curable resin layer through a mask having a through hole in a necessary portion, and adhesion of the resin layer surface (3) Spreading conductive particles on the surface of the resin layer and attaching conductive particles to the strongly adhesive portion. Step of forming conductive particle dense portion (4) The method of manufacturing a connection member according to the present invention comprises: About. (1) Step of forming a photo-curable resin layer on a peelable substrate (2) Irradiation of light to the photo-curable resin layer through a mask having a through hole in a necessary portion, and adhesion of the resin layer surface (3) Step of forming conductive particle dense part where conductive particles are dispersed on the resin layer surface and conductive particles are adhered to the strong adhesive part (4) At least on the weak adhesive part surface of the photocurable resin layer Step of forming an adhesive film

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view for explaining one embodiment of the present invention, and shows a method for manufacturing a connecting member. FIG. 1A shows a step of forming a photocurable resin layer 2 on a peelable substrate 1. Here, examples of the substrate 1 from which the photocurable resin layer 2 can be peeled include low surface tension materials such as polyethylene and polytetrafluoroethylene, and those obtained by subjecting polyethylene terephthalate or the like to a surface treatment with silicone or the like. As the photo-curable resin layer 2, one having both properties of photo-curability and thermal reactivity can be applied. The most common photocurable energy ray is that it also has thermal reactivity, but its main constituent material is a photocurable resin, a photoinitiator, and a mixture of resins and other additives. Is typical. FIG. 1B shows a step of irradiating the photocurable resin layer 2 with light 5 through a mask 3 having a through hole 4 in a necessary portion to form a strong and weak adhesive portion on the surface of the resin layer 2. . The mask 3 can be made of a plastic film, metal foil, glass, quartz, or the like, and is preferably surface-treated with a release agent in consideration of the time when the mask 3 is released. The mask 3 and the photocurable resin layer 2 are closely attached so that air bubbles do not enter, thereby improving the arrangement accuracy. FIG. 1C shows the strong adhesive part 6 and the weak part 7 obtained by (b).

FIG. 1D shows a process of forming a conductive particle dense portion where the conductive particles 8 are scattered on the surface of the photocurable resin layer and the conductive particles 8 are adhered to the strongly adhesive portion 6. As described above, a connection member having the conductive particle dense portions 10 (described later) arranged in a single layer on the surface of the photocurable resin layer is obtained. Conductive particles 8
Can be applied by spraying from a spray nozzle, for example, and the conductive particles 8 can be fixed to the strongly adhesive portion 6 preferably in a single layer. On the other hand, since the weak adhesive portion 7 has low adhesiveness, the conductive particles 8 hardly adhere. The mask 3 can be removed in FIG. 1C if the photo-curable resin layer 2 is a positive or negative type, but if the photo-curable resin layer 2 is left up to this step in the case of a positive type, the conductive particles 8 will become weak adhesive portions 7. Hard to adhere to Au, A9, N as the conductive particles 8
There are metal particles such as i, Cu, W, Sb, Sn, and solder, carbon, and the like, and the above-described conductive layer is formed on these and non-conductive polymer nucleus materials such as glass, ceramics, and plastics by coating. May be done. Further, insulating coated particles obtained by coating conductive particles with an insulating layer, and a combination use of conductive particles and insulating particles are also applicable. These conductive particles can be applied in a composite form, and in order to obtain a single layer on the surface of the photocurable resin layer and obtain good connection reliability, a material having a narrow particle size distribution is preferable. More preferably, the particle diameter is within ± 50%. A conductive layer formed on a hot-melt metal such as solder or a polymer nucleus material such as plastic is deformable by heating and pressing or pressurizing, increasing the contact area with the circuit during lamination and increasing reliability. It is preferable because it improves. In particular, when a polymer is used as a core, a softened state can be widely controlled by a connection temperature since a melting point is not exhibited unlike solder, and a connection member which can easily cope with variations in electrode thickness and flatness is obtained, which is preferable. In the case of hard metal particles such as Ni and W, for example, the conductive particles pierce the electrodes and wiring patterns, so that a low connection resistance can be obtained even in the presence of an oxide film or a contaminant layer. It is also effective in suppressing expansion and contraction due to heat and its reliability is improved.

FIG. 1 (e) shows a step performed as necessary to reduce the adhesive property of the photo-curable resin layer as a connecting member. Is formed (f). At this time, in order to maintain a dense area of the conductive particles, the adhesive film 9 may be used to form a sandwich (9) from both sides as needed. Also, the entire area or a part of the dense area 10 of the conductive particles can be buried in the strong adhesive portion 6 as shown in FIG. it can. In this case, since the hardening reaction has hardly progressed in the strong adhesive portion 6, the embedding is easy, and the weak adhesive portion 7
Since the reaction is in progress, the conductive particles are less likely to move out of the dense area 10 due to heating and pressurizing during connection. Thereafter, the adhesive film 9 can be formed as required. As the adhesive film 9, a thermoplastic material or a material showing curability by heat or light can be widely applied. The use of a curable material is preferred because of its excellent heat resistance and moisture resistance after connection. Among them, an epoxy adhesive is preferably applied because it can be cured in a short time, has good connection workability, and has excellent adhesiveness in terms of molecular structure. Epoxy-based adhesives are, for example, high-molecular-weight epoxies, solid epoxies and liquid epoxies, and epoxies modified with urethane, polyester, NBR, etc. as main components, and added with curing agents, catalysts, coupling agents, fillers, etc. Is common. The thickness of the adhesive film 9 is preferably as thin as about 100 μm or less, more preferably 50 μm or less, and more preferably 35 μm or less, from the viewpoint of improving the precision of forming a dense area of conductive particles, in a range where adhesiveness can be obtained.

The dense area 10 of the conductive particles will be described with reference to FIGS. As shown in FIG. 2, the dense region 10 of the conductive particles 8 maintains the insulation without conducting the adjacent parallel electrodes 11 and at least a part of the dense region 10 is always sandwiched between all the parallel electrodes to be connected. About to place. In the case of a dot-shaped electrode such as a semiconductor chip as shown in FIG. 3, the electrodes are arranged so that a dense area always exists on the electrode. In principle, the number of the conductive particles 8 in the dense region 10 may be one, but it is preferable that the number is two or more, more preferably five or more, because the connection reliability is improved. When the number of conductive particles 8 in the dense area is small, it is easy to obtain a high-resolution connection member.

According to the present invention, the conductive particles 8 can be fixed by a relatively simple method such as spraying from a spray nozzle, and the conductive particles 8 can be fixed to the strongly adhesive portion 6 preferably in a single layer. On the other hand, since the weakly adhesive portion 7 has low adhesiveness, the conductive particles 8
Is difficult to adhere. Therefore, a connection member in which the dense region of the conductive particles 8 and the portion without the conductive particles are separated can be obtained relatively easily. When the conductive particles 8 are present in a single layer in the connection member, the flow of the conductive particles 8 at the time of connection is reduced, which is effective in securing the number of conductive particles remaining on the connection electrode. At the time of connection, the strongly adhesive portion 6 has an electrode bonding function as a connection member because the photocuring function remains. According to the present invention,
By forming the adhesive film 9 on the surface of the weak adhesive portion 7 of the photocurable resin layer 1, the adhesive function of the weak adhesive portion 7 reduced by light irradiation can be added. It is effective in preventing falling off. Dense area 10 of conductive particles 8
Can be freely set by using the mask 3, which is effective for connection of a fine electrode which is remarkably developed. Further, according to the present invention, since the photocurable material can be applied to the connection of the fine electrodes, it is possible to lower the connection temperature and shorten the connection time. Therefore, high-accuracy positioning can be performed without electrode displacement.

[0010]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. Example 1 (1) Photo-curable resin layer Phenoxy resin (manufactured by Union Carbide Co., Ltd., PKHA) 50, photo-curable resin (3/1 weight ratio of epoxy acrylic oligomer and acrylate monomer) 50 by solid content weight ratio, Photoinitiator (benzophenone) 5, sensitizer (Michler's ketone) 1, vinyl silane coupling agent 5,
A 70% solution of toluene / ethyl acetate was obtained. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) with a roll coater,
After drying at 70 ° C. for 20 minutes, a photocurable resin layer having a thickness of 20 μm was obtained. (2) Dispersion of mask and conductive particles A stainless steel metal mask having a circular through-hole with regular triangles arranged without gaps and having a center at each vertex (thickness: 10 μm, size: 100 mm square, hole diameter: 20 μm, pitch: 50 μm) Was treated with a release agent to adhere to the photocurable resin layer. By irradiating ultraviolet rays (1.0 J / cm ² ) from above the metal mask, the adhesiveness of the resin layer at the mask opening was reduced. Thereafter, the mask was removed, and particles were scattered. Conductive particles have a particle size of 4 soil 0.2μ
m / polystyrene particles with a thickness of Ni / Au of 0.1 /
The conductive particles having a metal coating of 0.02 μm were fluidized through an air ejector and sprayed from a spray nozzle. In the densely packed region having a diameter of 20 μm, 5
There were more than one particle.

(3) Connection circuit A two-layer FPC circuit board having a 18 μm-high steel circuit on a polyimide film (circuit pitch: 70 μm, electrode width: 3 μm)
0 μm parallel circuit electrode) and 0.2 μm indium oxide thickness (1T0, surface resistance 20Ω) on 1.1 mm glass
/ □) was connected to a flat electrode having a thin film circuit.
First, the connection member was placed on the IT0 electrode side with a width of 1.5 mm, and the separator was peeled off and attached. Thereafter, the separator was peeled off, the FPC and the upper and lower circuits were aligned, and temporarily connected by the adhesiveness of the connecting member. Since the pitch of the particle dense region of the connecting member is finer than that of the connecting circuit, it is not necessary to align the two, and temporary connection similar to the conventional connecting member was possible. (4) Connection 70 ° C, 20 kgf / mm ² ,
Irradiation (2.0 J / cm) in close proximity to a glass pedestal using a light irradiation device (ultra high pressure mercury lamp) while applying pressure for 20 seconds.
² ) I did. The temperature of the connection was 100 ° C. or less. The thickness of the photocurable resin layer was large, the influence of the mask irradiation was small, and a weakly adhesive portion without conductive particles could be bonded. (5) Evaluation Both electrodes were viewed under a microscope and the maximum deviation between the electrodes was measured. The maximum deviation was 5 μm or less, and there was almost no deviation. When the connection resistance was evaluated as the connection resistance between the electrodes which were relatively different from each other and the insulation resistance was determined between the adjacent electrodes, the connection resistance was 2Ω or less and the insulation resistance was 10 ⁸ Ω or more. These are 85 ° C, 85%
The moisture resistance reliability after the RH treatment for 1000 hours showed almost no change, indicating good long-term connection reliability.

Example 2 Same as Example 1 except that the thickness of the photocurable resin layer was 10
μm, and an adhesive film was further formed thereon. The adhesive film was bonded to a substrate made of a severator obtained by treating a polyester film with a release agent, using a thermosetting adhesive having a tackiness at room temperature and a thickness of 10 μm containing a high-molecular-weight epoxy as a main component, using a roll laminator. .
The connection is made by a thermocompression bonding device (160 ° C, 20 kgf / mm ² , 2
0 seconds), good initial and long-term connection reliability was obtained. It is considered that the curing reaction was promoted during thermocompression bonding because the photocurable resin layer also has thermosetting properties.

Comparative Example 5% by volume of conductive particles were uniformly dispersed in the adhesive film of Example 2 to have a thickness of 20 μm. The connection member was image-analyzed, and the particle density in an area having a diameter of 20 μm was measured at 20 places. The results were compared with the particle density regions of Examples 1 and 2 measured in the same manner. Compared to the comparative example of uniform dispersion,
In each of Examples 1 and 2, there was little variation, and there was no portion where the number of particles was zero even in the minimum portion.

Example 3 The same as Example 2, except that the dense distribution of the conductive particles was changed to an arrangement as shown in FIG. For this purpose, a metal mask (thickness: 25 μm) having through holes with a diameter of 50 μm in the same arrangement as the electrode arrangement of the test IC chip (250 electrodes, height of the protruding electrode: 20 μm) was used. The connection was performed by a thermocompression bonding apparatus. The number of particles on the electrode was 5 or more, and the connection reliability was good.

[0015]

As described above in detail, according to the present invention, it is possible to provide a connecting member having a dense region of conductive particles with high precision in a main part, and an industrial production method thereof.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a connecting member and a method of manufacturing the connecting member according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of a dense region of conductive particles according to an embodiment of the present invention.

FIG. 3 is a schematic plan view of a dense region of conductive particles according to an embodiment of the present invention.

[Explanation of symbols]

 1 base material 2 photocurable resin layer 3 mask 4 through hole 5 light 6 strong adhesive part 7 weak adhesive part 8 conductive particles 9 adhesive film 10 particle dense area 11 parallel electrode 12 space part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H05K 3/36 H05K 3/36 A (72) Inventor Koji Kobayashi 1150 Goshomiya, Oji, Shimodate-shi, Ibaraki Prefecture Gosho, Hitachi Chemical Co., Ltd. Inside the Miya Factory (72) Inventor Yukihisa Hirosawa 1150 Goshomiya, Oji, Shimodate City, Ibaraki Pref.Hitachi Kasei Kogyo Co., Ltd. (72) Kazuya Matsuda 1150 Gozamiya, Shimodate, Ibaraki Hitachi, Hitachi Chemical Goshonomiya Factory Co., Ltd.

Claims (4)

[Claims] 1. A connection member comprising a photo-curable resin layer formed on a peelable substrate and a conductive particle dense portion disposed in a single layer formed on a surface of the photo-curable resin layer. 2. A photo-curable resin layer formed on a peelable substrate, comprising a conductive layer dense portion disposed on a single layer on a surface of the photo-curable resin layer, and an adhesive film on at least a part of the photo-curable resin layer. A connection member formed with. 3. A method for manufacturing a connecting member comprising the following steps. (1) Step of forming a photo-curable resin layer on a peelable substrate (2) Irradiation of light to the photo-curable resin layer through a mask having a through hole in a necessary portion, and adhesion of the resin layer surface (3) Step of dispersing conductive particles on the resin layer surface and attaching conductive particles to the strongly adhesive portion 4. A method for manufacturing a connecting member comprising the following steps. (1) Step of forming a photo-curable resin layer on a peelable substrate (2) Irradiation of light to the photo-curable resin layer through a mask having a through hole in a necessary portion, and adhesion of the resin layer surface (3) Step of forming conductive particle dense part where conductive particles are dispersed on the resin layer surface and conductive particles are adhered to the strong adhesive part (4) At least on the weak adhesive part surface of the photocurable resin layer Step of forming an adhesive film