JP2890890B2 - 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 conductive particles 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 the bump is sometimes 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 a bumpless connection method in which a semiconductor chip is used as a circuit material, for example, an aluminum wiring as it is, or a barrier metal layer for preventing metal diffusion is formed thereon as a connection electrode. 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 is 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 5
It is about 0 μm. These multiple electrodes are, for example, 0.5
It is extremely difficult to control the formation with a variation within 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 base material; (2) a step of bringing a mask having a through hole in a necessary portion into close contact with the surface of the adhesive layer; 3) irradiating excimer laser light from a through hole of the mask to form a hole in at least a part of the adhesive layer in the thickness direction; (4) arranging conductive particles in the hole from the through hole of the mask; (5) removing the mask from the surface of the adhesive layer;

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 the 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 with a sharp cross section can be provided, shape and position control at the micron level is possible, and the depth of the hole is ± 0.1μ.
It can be controlled with m precision. When a typical irradiation laser and wavelength are exemplified, ArF (193 nm), KrF (248 n
m), XeCl (308 nm), XeF (351 nm)
It is.

The present invention will be described below 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. At this time, it is preferable to form an adhesive layer on the substrate 1 from which the adhesive layer 2 can be peeled off. 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.

As the adhesive 2, it is preferable to use a curable insulating material having excellent heat resistance and moisture resistance after connection. Among them, an epoxy adhesive can be cured in a short time and has good connection workability. It is preferable because of its characteristics such as 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, and an epoxy resin modified with urethane, polyester, NBR, or the like, and a latent curing agent or a coupling agent. And those containing various modifiers, catalysts and the like.

These adhesives having tackiness at around room temperature facilitate the placement and fixing of the conductive particles. The thickness of the adhesive layer is preferably from 5 to 70 μm, and more preferably from 10 to 35 μm in order to obtain good connection reliability.

Next, in step (2), a mask 4 having a through hole 3 at a necessary portion is brought into close contact with the surface of the adhesive layer 2. Here, the arrangement of the through-holes should coincide with the arrangement of the electrodes to be connected, and at least the arrangement of the center point of the through-holes and the electrodes should be matched. For the formation of the through holes of the mask, YAG, carbon dioxide laser, precision drill, etching by plasma or chemical solution, and gold steel formed by fibrous material are used.

The mask 4 only needs to be able to shield the laser beam, and various metals such as stainless steel, Al, Cu, Zn, Ti, and Be can be preferably used. Ceramics, glass, quartz, and metal thin films formed on these materials can be used. Applications such as things are possible. Further, the mask needs to be able to be peeled off from the adhesive layer in the final step, and the surface may be treated with a peeling agent.

The mask is brought into close contact with the surface of the adhesive layer by a roll, a heating roll, a press between parallel plates or the like so that air bubbles do not enter. When air bubbles enter, the accuracy of the arrangement of the conductive particles decreases. The thickness of the mask is not particularly limited, but is determined in consideration of the above-described workability, the particle size of the conductive particles to be used, and the like.

Next, in the step (3), a laser beam is applied to the adhesive surface from the through-hole 3 of the mask that is in close contact.
A hole having a desired depth can be formed in the thickness direction of the adhesive layer by adjusting the beam diameter, the number of repetitions, the pulse width, the output, and the wavelength at the time of irradiation. The holes may be through holes. When an excimer laser is used, only the adhesive in the through hole can be ablated even when the entire surface is irradiated with the excimer laser from above the mask. The reason for this is that the mask material, such as metal or ceramic, has a higher binding energy and a lower excimer laser transmittance than a polymer material such as an adhesive.

Here, for example, by narrowing the beam diameter, it is also possible to form a hole in only a small part of the area of the through-hole. For example, the precision of the mask is such that the opening area of the mask is 20 μm square compared to 40 μm square. The above high-precision processing is also possible. Also, when cutting the periphery of the connection member, the connection member can be cut with high precision dimensions by irradiating an excimer laser by providing an opening in a portion of the mask that requires cutting. 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.

After the excimer laser irradiation step, the film mask may be changed to a general so-called film mask, or, of course, the original mask may be used as it is.

Next, in the step (4), the conductive particles 5 are arranged in the holes from the through holes of the mask. The conductive particles 5 used in the present invention are Ni, Fe, Cr, Co, Al, Sb, Mo, P
Metals such as b, Sn, In, Cu, Ag, and Au, oxides of these, and composites or alloys of two or more of these, or general conductive particles made of carbon or the like may be used. In addition, it can be used as long as at least the surface of the particles is conductive.

Among these conductive particles, particles exhibiting deformability under conditions such as heating, pressurizing, and heating and pressurizing at the time of connection can be preferably applied. As the deformable particles, for example, the surface of a polymer core material such as polystyrene or epoxy resin is
Examples include particles coated with a thin conductive metal layer such as i, Ag, Au, Cu, and solder, and low melting point metal particles. Conditions for connection include, for example, a temperature of 250 ° C. or less, a pressure of 100 kgf.
/ Cm ² or less and the time is generally 30 seconds or less.
It is preferable that the temperature is not higher than 00 ° C. and the pressure is not higher than 50 kgf / cm ² . 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-holes can be either single particle arrangement (a, b) or plural particle arrangements (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 do not easily fall off when coming into contact with the adhesive 2. In the case of performing the surface treatment, there is an advantage that small-diameter particles can be formed densely.

Next, in step (5), the connection member in which the conductive particles 5 are disposed and fixed on the adhesive layer 2 by removing the mask is obtained.

The connecting 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 5 , And then comes into contact with the electrode and deforms, enabling connection of both circuits. The step (6) is performed as needed after the step (5), and includes the substrate 1 'and the adhesive layer 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 5 may be in a state in which the conductive particles are not buried in the adhesive and the conductive particles are exposed and protrude from the adhesive surface.

FIG. 3 shows another embodiment according to the present invention. FIG. 3A shows that a part of the adhesive layer 2 is ablated by an excimer laser to form a shallow hole, and then the particles 5 are formed.
Is arranged. The present invention can be implemented as long as the conductive particles can be fixed even in a shallow hole. FIG. 3B shows a structure in which through-holes are formed in the thickness direction of the adhesive layer 2 and overlapped. Since the excimer laser is used, the sidewalls can be manufactured precisely, so that the conductive particles 5 can be densely filled. In addition, since the conductive particles can be formed so as to protrude from the bonding surface, the connection resistance is low, and the position is improved by coloring the conductive particles. It has features such as easy matching.

[0028]

According to the present invention, a mask having a through-hole can be adhered to a necessary portion on the adhesive, so that the mask is fixed by the adhesive and accurate drilling can be performed without causing displacement. The mask is made of a material capable of blocking the excimer laser, so that only the through holes can be irradiated. The adhesive can be ablated with an excimer laser that has reached the adhesive surface from the through-hole, and can be removed with high precision. At this time, the excimer laser device has a beam diameter of about 1 for example.
Since it is relatively large as × 2 cm ^2, it is possible to irradiate a wide area, and the number of repetitions can be continuously varied from 1 to several 100 Hz. Also, by narrowing the beam, only a part of the through hole area of the mask can be ablated, so that a hole having an area smaller than the limit of the mask accuracy can be provided. Then, by disposing the conductive particles in the hole, it is possible to easily manufacture a connection member in which the conductive particles are disposed only in a necessary portion of the adhesive layer. 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 in a clean atmosphere becomes possible.

[0029]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 In FIG. 1, a polytetrafluoroethylene film was used as a base material 1 and an insulating adhesive mainly composed of an epoxy-based adhesive was applied on the base material 1 to form an insulating film having a thickness of about 20 μm. Adhesive layer 2 was provided. Next, a 30 μm thick stainless steel metal mask 4 having a through hole 3 having a diameter of 80 μm in the same arrangement as the electrodes of the test IC chip to be connected.
Was adhered to the insulating adhesive layer 2. A laminator using a rubber roll was used for the adhesion, and floating between the metal mask 4 and the adhesive 2 was prevented as much as possible. Next, this metal mask 4
Was irradiated with an excimer laser having a wavelength of 248 nm, and a hole having a depth of about 15 μm was formed in the adhesive 2. next,
After the deformable conductive particles 5 (average particle size: 10 μm) having a thin metal layer of Au on the surface of a polystyrene high molecular core material are sprayed on the metal mask 4, the metal is spread using a rubber squeegee or brush. The conductive particles 5 were pushed into the through holes 3 of the mask 4, and excess conductive particles 5 were removed from the metal mask 4. Next, the metal mask 4 is applied to the insulating adhesive 2.
To obtain a desired connection member.

Example 2 As shown in FIG. 1 (5), 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 ′ layer was adhered to the insulating adhesive layer 2 of the connecting member shown in Example 1 to obtain a connecting member.

Example 3 In the connection member shown in Example 1, a layer of an acrylic resin 6 having a thickness of 20 μm was formed on the surface of the conductive particles 5 by using a coatmizer (manufactured by Freund Corporation) instead of the conductive particles 5. A connection member was obtained in the same manner except that the conductive particles 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 was the same.

Using the connection members of Examples 1 to 4, a test IC in which bumps having an electrode diameter of 80 μm and a distance between electrodes of 40 μm were arranged was connected to a glass substrate having ITO electrodes arranged in the same manner as the test IC, and the connection resistance was measured. The results of measuring the insulation resistance between adjacent electrodes are shown in the table below. 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.

[0034]

[Table 1]

[0035]

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 showing a state of conductive particles.

FIG. 3 is a schematic cross-sectional view showing another embodiment of the connection member according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2 Adhesive layer 3 Through-hole 4 Mask 5 Conductive particle 6 Resin layer

Continued on the front page (72) Inventor Kyohisa Ota 1500 Oji Ogawa, Shimodate City, Ibaraki Pref.Hitachi Kasei Kogyo Co., Ltd. Inside the Shimodate Research Laboratory (72) Inventor Tatsuo Ito 1150 Goshomiya, Oaza, Shimodate, Ibaraki Prefecture Inside the Goshomiya Plant, Hitachi Chemical Co., Ltd. (72) Naoki Fukutomi 48 Tsukuba Wadai, Ibaraki Prefecture In-house (72) Inventor Yoshiaki Tsubomatsu 48 Tsukuba-wadai, Ibaraki Pref., Tsukuba Development Laboratory, Hitachi Chemical Co., Ltd. (56) References JP-A-61-187393 (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) a step of forming an insulating adhesive layer made of an epoxy-based adhesive on a peelable substrate; (2) a mask having a through-hole at a necessary portion is provided on the surface of the adhesive layer (3) a step of irradiating an excimer laser beam from a through hole of a mask to form a hole in at least a part of the adhesive layer in a thickness direction; and (4) a step of introducing conductive particles from the through hole of the mask into the hole. Disposing and (5) removing the mask from the surface of the adhesive layer.