JP2890891B2 - Manufacturing method of connecting member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a connecting member used for electrically connecting opposed electrodes or circuits and for bonding and fixing them.

[0002]

2. Description of the Related Art Electrodes of semiconductor chips such as ICs, LSIs, chip capacitors and the like are directly connected to a substrate circuit formed by forming a predetermined circuit on the surface of a substrate made of glass, synthetic resin, metal, or the like, or these substrates are connected to each other. As a method of connecting so-called high-density electrodes for directly connecting circuits, a method of connecting electrodes facing each other or a circuit via a connection member mainly composed of an adhesive between circuits is known.

[0003] Examples of the use of this connecting member include carbon, nickel, solder and plastic particles having a conductive layer formed on the surface thereof in an insulating adhesive as shown in Japanese Utility Model Application Laid-Open No. 62-107444. A method of obtaining electrical connection in the thickness direction by applying pressure using an anisotropic conductive adhesive mixed with conductive particles, and a method of directly contacting the electrode surface by applying pressure when connecting an insulating adhesive without using a conductive material A method is known in which an electrical connection is obtained and the remaining adhesive is removed outside the circuit for connection.

In the case of a semiconductor chip as a typical example of a high-density electrode, a protruding electrode called a bump is often formed on a chip surface, and this bump may be provided on a substrate circuit. In any case, the bump formation requires a complicated process, and has a problem that the production cost is high due to the occurrence of defects and a decrease in yield, and the consumption of precious metals such as Au, Ag, Cu and solder which are bump materials. doing. For this reason, some attempts have been made to use bumpless bonding as a connection electrode in a state where a semiconductor chip is a circuit material, for example, aluminum wiring as it is, or a barrier metal layer for preventing metal diffusion is formed thereon. However, it is difficult to put it to practical use due to insufficient properties.

In the connection method using an adhesive using conductive particles, if the number of particles on an electrode is increased in order to improve the reliability of electrical connection, the particles are present at a high density between adjacent electrodes. Insufficiency in insulation, leaks and short-circuits, and other problems occur in maintaining insulation.
Conversely, when the number of particles is reduced, the number of particles on the electrode becomes insufficient and the connection reliability decreases. This contradictory tendency is further promoted by the phenomenon that the conductive particles flow out of the electrodes together with the adhesive due to heating and pressurizing at the time of connection.
It has been difficult to cope with high-density connections such as μm or less.

The connection method using an insulating adhesive has good insulation properties between adjacent electrodes, but has a disadvantage that it is difficult to obtain reliable connection reliability due to variations in bump height. That is, the number of bumps per chip is as large as 10 to 500, for example, and the bump height is 1 to
It is about 50 μm. These multiple electrodes are, for example,
It is extremely difficult to control the formation with a variation within 5 μm. If the bump heights are not uniform, the larger bumps can easily contact the circuit surface of the board, but the lower bumps will create an air gap between the bumps and the circuit board, making electrical connection possible. I can't. Further, this method has a disadvantage that it cannot be applied in principle to the bumpless connection method, which is a promising method for cost reduction, because it is difficult to obtain electrode contact.

For the purpose of breaking the road in the adhesive system, for example, Japanese Patent Application Laid-Open No. 63-276237 and Japanese Patent Application Laid-Open
As disclosed in, for example, JP-A-289824, there is also an attempt to form a conductive adhesive only on a bump and connect it to a substrate circuit. In these methods, in order to form the conductive adhesive in the required portion, a conductive adhesive application step is required,
There are problems such as a decrease in cleanliness and a deterioration in the working environment due to the introduction of a volatile organic solvent into a semiconductor manufacturing process in which cleanliness is particularly important.

Further, the method of applying a conductive adhesive to a necessary portion by coating or transfer method is close to the limit of the manufacturing technology in terms of a silk screen, a transfer jig, and the like, and corresponds to a higher density. Had become difficult.

[0009]

SUMMARY OF THE INVENTION The present invention is excellent in connection reliability and insulation properties in a small area, enables connection of high-density electrodes, and regardless of whether bumps are formed on a semiconductor chip and / or a circuit. It is another object of the present invention to provide a method for manufacturing a connecting member which can be applied without using an organic solvent or a conductive adhesive in a semiconductor manufacturing process.

[0010]

That is, the present invention relates to a method for manufacturing a connecting member comprising the following steps. (1) a step of forming an insulating adhesive layer made of an epoxy-based adhesive on a peelable substrate, and adhering a film on the adhesive layer; (2) applying excimer laser light to necessary portions on the film (3) a step of irradiating only the film to form a hole in at least a part of the adhesive layer in the thickness direction of the adhesive layer through the film;

The present invention is characterized in that a laser beam is used as a means for forming a hole in a necessary portion of the adhesive layer. As a laser, a YAG laser or a carbon dioxide laser can be used, but in the present invention, it is preferable to use an excimer laser. The excimer laser is described in detail in, for example, Functional Materials, October and November 1989, issued by CMC Corporation. An excimer laser is a laser that can oscillate high-energy photons in the ultraviolet region necessary for directly breaking chemical bonds with high intensity.

When this laser is irradiated, the irradiated portion is instantaneously decomposed and scattered with plasma emission and impact sound (ablation). By using this laser, a hole having a sharp cross section can be provided, the shape and position can be controlled at the micron level, and the depth can be controlled with an accuracy of ± 0.1 μm. Typical irradiation lasers and wavelengths are, for example, ArF (193 nm), KrF (248 nm),
XeCl (308 nm) and XeF (351 nm). Means for irradiating the excimer laser only to the necessary parts on the film include, without transmitting the excimer laser light, and easily decomposing even when irradiated with the excimer laser light, stainless steel, Al, Cu, Zn,
A method in which a mask made of various metals such as Ti, ceramics, glass, quartz, and a metal thin film formed on the same and having a through hole at a necessary portion is adhered to the film, and an excimer laser is irradiated onto the mask, There is a method in which a mask made of the above-described material is fixed between a light emitting source of an excimer laser and a film so that laser light transmitted through the mask is irradiated only to a necessary portion. In the latter method, an optical lens is provided between the mask and the film, and the laser light transmitted through the mask can be reduced by the optical lens, and a hole smaller than the penetrating light provided in the mask is provided in the film and the adhesive layer. This is suitable as a method for producing a finer circuit connection member than the former method.

Hereinafter, the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing a method for manufacturing a connection member.
In the step (1), the adhesive layer 2 is formed, and the film 3 is adhered on the adhesive layer 2. At this time, it is preferable to form the adhesive layer on the substrate 1 from which the adhesive layer can be peeled. The substrate 1 and the film 3 need to be peelable from the adhesive 2. The base material 1 is a material used as needed, and is formed on one side or both sides of the connection member, and can prevent adhesion of dust and the like. In using the base material 1, it is necessary that the connecting member be peelable at the time of use. As an index, it is preferable that the wetting tension according to JIS K-6768 is 35 dyn / cm or less. For this purpose, it is preferable to use a low surface tension material such as polyethylene or polytetrafluoroethylene, or to use polyethylene terephthalate or polyimide which is surface-treated with the above low surface tension material or silicone.

For the adhesive layer 2, a thermoplastic insulating material used for an adhesive sheet or the like, or a curable insulating material which is curable by heat or light is widely used. It is preferable to use a curable insulating material because of its excellent heat resistance and moisture resistance after connection. Among them, an epoxy adhesive is preferably used because it can be cured in a short time, has good connection workability, and has excellent adhesiveness in molecular structure. Examples of the epoxy adhesive include a high-molecular-weight epoxy resin, a mixture of a solid epoxy resin and a liquid epoxy resin, urethane and polyester,
A resin composed mainly of an epoxy resin or the like modified with NBR or the like, and added with various modifiers such as a latent curing agent and a coupling agent, a catalyst, and the like is used.

When these adhesives have tackiness at around room temperature, the conductive particles can be easily arranged and fixed. The thickness of the adhesive layer is preferably 5 to 70 μm or less, and more preferably 10 to 35 μm in order to obtain good connection reliability.
As the film 3, the same material as the above-described substrate 1 is used, and it is preferable that the film 3 can be separated from the adhesive 2. However, when the adhesion between the film 3 and the conductive particles 6 is low and the amount of the conductive particles 6 attached to portions other than the through-holes 4 is small, for example, various plastic films modified with a carboxyl group, a hydroxyl group, or the like. Using an adhesive film, the film can be used as an adhesive without peeling. The adhesive layer is brought into close contact with a commonly used method such as lamination by a film roll or a press.

Next, in the step (2), the film 3
A laser beam, preferably an excimer laser, is applied to only the above necessary parts (2-1). Here, the necessary parts should match the arrangement of the electrodes to be connected, and at least the arrangement of the center point of the excimer laser beam 5 matches the electrodes.

By adjusting the beam diameter, the number of repetitions, the pulse width, the output, the wavelength, and the like at the time of excimer laser irradiation, a hole having a desired depth can be formed through the film 3 in the thickness direction of the adhesive layer 2. . The holes may be through holes. In the excimer laser device, the beam diameter of the light emitting unit is, for example, 1 ×
Relatively large, 2 cm ^2, and the number of repetitions is one to several hundred
Since the frequency can be continuously changed to Hz, a hole having a desired depth can be formed only in a necessary portion by irradiation for several seconds (2-2). Also, when cutting the periphery of the connection member, the connection member can be cut with high precision dimensions by irradiating a portion requiring cutting with an excimer laser. Since the excimer laser can perform ablation in the depth direction, it can be used as a holding material without cutting the adhesive layer but cutting the base layer. According to this cutting method, no deformation or damage is caused around the cut portion.

Next, in the step (3), the film is removed if necessary, and the conductive particles 6 are disposed in the through holes (see FIG.
1) (3-2). The conductive particles 6 used in the present invention are Ni, F
e, Cr, Co, Al, Sb, Mo, Pb, Sn, I
Metals such as n, Cu, Ag, Au, etc., their oxides and composites or alloys of two or more thereof, or carbon, may be any general conductive particles made of organic conductors and the like. In addition, it can be used as long as at least the surface of the particles is conductive.

Among these conductive particles, heating during connection,
Particles exhibiting deformability under conditions such as pressurization and heating and pressurization can be preferably applied. As the deformable particles, for example, the surface of a polymer nucleus material such as polystyrene or epoxy resin may be Ni, A
g, Au, Cu, solder, and other particles coated with a thin conductive metal layer, and low-melting metal particles. Conditions for the connection include, for example, a temperature of 250 ° C. or less and a pressure of 100 kgf / cm.
² or less, time 30 seconds or less is common, and the higher the temperature and pressure, the more heat damages the surrounding materials.
Hereinafter, the pressure is preferably set to 50 kgf / cm ² or less. Confirmation of the deformation of the conductive particles is performed by observing the cross section of the connection body with an electron microscope. The average particle size of the conductive particles is preferably a small particle size of 30 μm or less, and more preferably about 3 to 15 μm in order to correspond to a high-density electrode arrangement.

As shown in FIG. 2, the arrangement of the conductive particles in the through-hole can be performed by either single particles (a, b) or plural particles (c, d, e, f). is there.
In the case of a plurality of particles, it can be arranged by the cohesive force between the particles or the adhesive force of the adhesive resin used for the surface treatment of the particles. The conductive particles may be directly provided (a, c, e) in the through-hole. Alternatively, a surface treatment such as coating (b, d) the surface with a resin or dispersing (f) conductive particles in the resin may be used. In the case where the surface treatment of the conductive particles is not performed, it is preferable that the conductive particles are in the form of a single particle (a) because the particles are hardly dropped off by contact with the connecting agent 2. In the case of performing the surface treatment, there is an advantage that small-diameter particles can be formed densely.

Through the above steps, a connecting member in which conductive particles are localized in necessary parts can be manufactured. The connection member thus obtained is disposed between the electrodes to be connected by removing the base material 1 as necessary, and, for example, by applying heat and pressure, the conductive particles 6 are buried in the adhesive 2. Then, by contacting and preferably deforming with the electrode, the contact area with the electrode surface is increased, and a highly reliable connection with both circuits can be obtained. The step shown in FIG. 1 (4) is performed as necessary after the step of (3), and includes a substrate 1 'and an adhesive 2'.
And a laminated adhesive film. In this case, the conductive particles can be fixed also from the upper part, so that the conductive particles hardly fall off, and since both surfaces are covered with the base materials 1 and 1 ', it is effective to prevent the adhesion of dust. The conductive particles 6 may not be buried in the adhesive 2 and may be in a state where the conductive particles are exposed and protrude from the adhesive surface.

FIG. 2 shows another embodiment according to the present invention. FIG. 2A shows that a part of the adhesive layer 2 is ablated by an excimer laser to form a shallow hole, and then the particles 6 are removed.
Is arranged. The present invention can be implemented as long as the conductive particles can be fixed even in a shallow hole. FIG. 2B shows a structure in which through-holes are formed in the thickness direction of the adhesive layers 2 and 2 'and are superposed. Since the excimer laser is used, the sidewalls can be manufactured precisely, so that the conductive particles 6 can be densely filled.
In addition, since the conductive particles can be formed so as to protrude from the adhesive surface, they have characteristics such as low connection resistance and easy alignment by coloring the conductive particles.

[0023]

According to the present invention, a film which can be decomposed by an excimer laser is brought into close contact with the adhesive layer in advance, and the excimer laser is irradiated to a necessary portion of the film, and the film is bonded to a film having a through hole only in the necessary portion. A hole having a desired depth can be formed in the agent, and the conductive particles can be disposed in the hole of the adhesive through the through hole of the film. As long as this film can be decomposed by an excimer laser, a film made of various materials can be used, and in consideration of characteristics such as adhesion to an adhesive and releasability, price, etc., from a material excellent in various characteristics. Film can be selected. In addition, since there is no through-hole on the film before excimer laser irradiation, by placing the film on an adhesive, contamination by dust or the like can be prevented, and handling becomes easy. The connection member according to the present invention can be applied regardless of the presence or absence of bump formation on a semiconductor chip and / or a circuit by arranging conductive particles only in a necessary portion. Connection work can be performed in a clean atmosphere.

[0024]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. Example 1 In FIG. 1, a film made of polytetrafluoroethylene was used as a substrate 1, and an insulating adhesive 2 containing an epoxy-based adhesive as a main component was applied onto the substrate 1, and the thickness was about 20 μm.
Was provided. Next, a polyimide film 3 having a thickness of 35 μm was brought into close contact with the insulating adhesive layer 2. The adhesion between the polyimide film 3 and the adhesive layer 2 was prevented as much as possible by using a laminator using a rubber roll for adhesion. Next, the same array as the electrodes of the test IC chip connected to the surface of the polyimide film 3 was irradiated with an excimer laser 5 having a wavelength of 248 nm by a mask imaging method to form holes 4 having a diameter of 80 μm. The holes 4 penetrate the polyimide film 3 and have a depth of about 15 μm in the adhesive 3. Next, after deformable conductive particles 6 (average particle size: 10 μm) having a thin metal layer of Au on the surface of a polystyrene polymer core material are sprayed on the polyimide film 3, a rubber squeegee or brush is applied. The conductive particles 6 were pushed into the through-holes 4 of the polyimide film 3 using the same, and excess conductive particles 6 were removed from the polyimide film 3. Next, the polyimide film 3 is applied to the insulating adhesive 2
To obtain a desired connection member.

Example 2 As shown in FIG. 1 (4), an insulating adhesive 2 'containing an epoxy-based adhesive as a main component was applied onto a substrate 1' of a polytetrafluoroethylene film, and the thickness was about A 10 μm layer of the insulating adhesive 2 ′ was provided, and the insulating adhesive 2 ′ was adhered to the surface of the insulating adhesive 2 in the connecting member of Example 1 to obtain a connecting member.

Example 3 In the connection member shown in Example 1, a 20 μm-thick layer of an acrylic resin 7 was formed on the surface of the conductive particles 6 by using a coatmizer (manufactured by Freund Corporation) instead of the conductive particles 6. A connection member was obtained in the same manner except that the conductive particles 6 provided with were used.

Example 4 A connection member was obtained by laminating the two connection members shown in Example 1 with the adhesive layers facing each other so that the arrangement of the conductive particles 6 matched.

The connecting member of the first to fourth embodiments has an electrode diameter of 80.
The following table shows the results of measuring the connection resistance and the insulation resistance between adjacent electrodes by connecting a test IC in which bumps with an interelectrode distance of 40 μm were arranged to a glass substrate having ITO electrodes arranged in the same manner. . The connection resistance indicated the average value of the electrodes at 60 points, and the insulation resistance indicated the minimum value of the measured values at 56 points.

[0029]

[Table 1]

[0030]

According to the present invention, conductive particles are localized in portions requiring electrical connection, and insulating portions are used with an insulating adhesive, so that minute portions can be easily connected. It is possible to relatively easily manufacture the connecting member to be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a method for manufacturing a connection member according to the present invention.

FIG. 2 is a schematic cross-sectional view illustrating a method for manufacturing another connecting member according to the present invention.

FIG. 3 is a schematic cross-sectional view showing a state of conductive particles.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2 Adhesive layer 3 Film 4 Through hole 5 Excimer laser beam 6 Conductive particle 7 Resin layer

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor, Kyohisa Ota, 1500, Oji, Oji, Shimodate-shi, Ibaraki Hitachi Chemical Co., Ltd. (72) Inventor Tatsuo Ito 1150 Goshomiya, Oaza, Shimodate-shi, Ibaraki Prefecture Hitachi Chemical Co., Ltd.Goshomiya Plant (72) Inventor Naoki Fukutomi 48 Tsukubadai, Ibaraki Hitachi Chemical Co., Ltd. Inside Tsukuba Development Laboratory (72) Inventor Yoshiaki Tsubomatsu 48 Tsukuba Wadai, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Tsukuba Development Laboratory (56) References JP-A-61-264604 (JP, A) JP-A-61-239576 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H01R 11/01 H01R 43/00

Claims (1)

(57) [Claims] 1. A method for manufacturing a connecting member comprising the following steps. (1) Absence of epoxy adhesive on peelable substrate
Forming an edge adhesive layer and adhering the film on the adhesive layer; (2) irradiating only necessary portions on the film with excimer laser light to penetrate through the film and obtain a thickness of the adhesive layer A step of providing holes in at least a part of the direction; (3) a step of disposing conductive particles in the holes from the through holes of the film.