JPH10139893A - Fiber reinforced, nonconductive and highly thermoconductive plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fiber reinforced, nonconductive and highly thermoconductive plastic having improved thermal conductivity without reducing the nonconductive properties of the plastic and suitable as a sealing material for a semiconductor by compounding an aluminum nitride fiber having an average fiber length within a prescribed range. SOLUTION: This fiber reinforced, nonconductive and highly thermoconductive plastic is obtained by compounding aluminum nitride fiber, preferably of 30-80vol.%, having 50-800μm average fiber length and obtained by milling an amorphous alumina filament in a pot mill made of alumina and thereafter performing nitration treatment thereof. Moreover, a nonconductive filler material for fiber reinforcement having high thermal conductivity is obtained from the aluminum nitride fiber having 2-10μm average fiber diameter and 50-800μm average fiber length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a fiber-reinforced insulating material.
More specifically, the present invention relates to a fiber-reinforced insulating and high heat conductive plastic which has excellent insulating properties and high heat conductivity and is particularly suitable as a sealing material for semiconductors.

[0002]

2. Description of the Related Art A composite material FRP (Fiber) reinforced with a high-strength fiber made of an inorganic or synthetic polymer.
Reinforced Plastics) is a plastic that is inferior in heat resistance and mechanical strength compared to metal materials with other materials, and is easy to mold and has high strength. Widely used. FRP generally comprises an unsaturated polyester resin,
A resin such as a polyamide resin or an epoxy resin is mixed with a ceramic fiber such as a glass fiber or a carbon fiber as a reinforcing material, or an organic polymer fiber such as an aramid fiber, and is used after molding. In recent years, an application of FRP for sealing a semiconductor chip has been attempted. Conventionally, semiconductor chips are conventionally sold on the market by using a sealing material such as a resin or ceramics to block them from the outside air. In general, resins that are less expensive than ceramics are frequently used, and epoxy resins are generally used.

As a sealing material for a semiconductor, it is necessary to guarantee the quality of a product semiconductor. Therefore, it is desired that the sealing material be not only insulative but also thermally conductive to prevent a temperature rise. . Conventionally used resins such as epoxy resin have excellent insulation properties, but have a drawback that they have poor thermal conductivity. For this reason, as described above, FRP as a semiconductor encapsulating material has been proposed from the viewpoints of enhancing mechanical strength and improving thermal conductivity. This is because the fibrous materials are entangled with each other and the number of contact points is increased, so that heat is easily conducted through the fibers, so that the thermal conductivity can be increased. However, in the conventional FRP, those having excellent insulation properties and sufficient high thermal conductivity are:
The fact is that it has not been developed yet. For example, a conventional FRP using glass fiber or organic polymer fiber has excellent insulation properties but poor thermal conductivity. Further, FRP using metal fiber or carbon fiber has good heat conduction because metal and carbon are good heat conductors, but cannot maintain insulation.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to develop an FRP having high strength, high thermal conductivity, and excellent insulation in view of the above-mentioned current situation of FRPs for semiconductor encapsulation. For this purpose, the inventors have selected and studied ceramics as a fiber material capable of providing high thermal conductivity without impairing the insulating properties of plastic. As a result, we focused on aluminum nitride (AlN), which has high thermal conductivity and is being developed as a material for semiconductor device substrates, from various ceramics, and conducted various studies from the viewpoint of fiber materials for FRP separately from those for semiconductor substrates. Was done. According to those studies, AlN fiber developed as an insulating and high thermal conductive filler material has been conventionally manufactured by a sublimation recrystallization method or a direct nitriding method of metallic aluminum, and has a fine fiber diameter of 1 μm or less. It has been found that, since the length is short, the fiber yield is low, and a large amount of particulate matter is mixed, the effect of increasing the contact points of the fibers is low, and the desired thermal conductivity cannot be improved.

On the other hand, the applicant has previously filed Japanese Patent Application No. 7-20602.
No. 7 proposed a method for producing AlN fibers in which no particulate matter was mixed. In this method, the γ-
This is a method in which alumina fibers are converted into AlN fibers by nitriding, and it is possible to manufacture AlN fibers with almost no particulate matter mixed therein. For this reason, the inventors decided to apply the AlN fiber obtained by the above-mentioned proposed method as a filler material for FRP. However, the AlN fiber obtained by the above method has a diameter of 2 to 4 μm and a length of several millimeters, and the fiber length is too long. Was done. In addition, this AlN
When shortening the fiber by treating the length of the fiber by crushing or the like, it was also confirmed that when the length was shorter than a predetermined value, no improvement in thermal conductivity was observed.

[0006] The inventors have further studied based on the above findings in order to facilitate the compounding of AlN fiber and plastic and to obtain an FRP having excellent insulating properties and thermal conductivity. As a result, it has been found that by setting the fiber length of the AlN fiber to a predetermined value, the compounding of the AlN fiber and the plastic is facilitated, and the thermal conductivity can be improved without impairing the insulation of the plastic, and the present invention has been completed.

[0007]

According to the present invention, there is provided a fiber-reinforced insulating and high-thermal-conductivity plastic comprising an aluminum nitride fiber having an average fiber length of 50 to 800 μm. . In the fiber-reinforced insulating and high thermal conductive plastic of the present invention, the compounding ratio of the aluminum nitride fiber is preferably from 3 to 80% by volume.
Also, as the aluminum nitride fiber, one obtained by pulverizing long fibers of aluminum nitride with an aluminum nitride pot mill, or one obtained by pulverizing long fibers of amorphous alumina with an alumina pot mill and then nitriding Preferably, it is

In the present invention, the average fiber diameter is 2 to 10 μm.
m, and made of aluminum nitride fiber having an average fiber length of 50 to 800 μm.
Provide a high thermal conductive filler material. In the insulating and high thermal conductive filler material of the present invention, it is preferable that the aluminum nitride fibers are obtained by grinding long fibers of aluminum nitride with an aluminum nitride pot mill.

[0009] The fiber-reinforced insulating and high thermal conductive plastic of the present invention is constituted as described above, and since the fiber length of the AlN fiber to be blended is set to a predetermined length, it is easy to compound the AlN fiber with the plastic. The obtained fiber-reinforced plastic can maintain good properties of the plastic and maintain insulation properties, and at the same time, AN fibers are uniformly mixed and
Since the 1N fibers are sufficiently entangled with each other to form many contact points, the thermal conductivity is significantly improved.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In the fiber reinforced insulating and high heat conductive plastic of the present invention, the plastic used is not particularly limited, and a resin used for ordinary FRP can be used. For example, a thermosetting resin such as unsaturated polyester, epoxy, or polyimide, or a thermoplastic resin such as polyamide, polycarbonate, polyacetal, or polysulfone can be used. In particular, an epoxy resin having excellent adhesiveness is suitably used as a sealing material for a semiconductor chip.

The AlN fiber which constitutes the fiber-reinforced insulating and high thermal conductive plastic of the present invention together with the above-mentioned plastic and exhibits excellent high thermal conductivity has an average fiber length of 50 to 800 μm, preferably 100 to 800 μm. 400
μm AlN fibers are used. Average fiber length is 50μ
If it is shorter than m, the number of contact points due to entanglement of the fibers required for improving thermal conductivity is small when blended with plastic, and the effect of improving thermal conductivity is small. On the other hand, if the average fiber length exceeds 800 μm, it becomes difficult to form a composite with a plastic and to form a molded body as described above. The AlN fiber used in the present invention can be obtained by nitriding an alumina fiber. However, in order to make the fiber length within the above range, if the alumina fiber is amorphous, it is pulverized by an alumina pot mill and then subjected to nitriding treatment. When the alumina fiber is in the γ-alumina phase, nitriding treatment
After converting to 1N, the mixture is pulverized with an aluminum nitride pomill to adjust the fiber length to the above range. When the alumina fiber of the γ-alumina phase is pulverized and then nitrified,
Although the reason is not clear, conversion to AlN is not performed smoothly, and α-
This is because a mixed phase of alumina and AlN tends to be formed. In addition, the knowledge of the change with time in this short fiber shortening,
It has been clarified for the first time by the inventors.

The AlN fiber of the present invention can be obtained, for example, by making the AlN fiber produced based on Japanese Patent Application No. 7-206027 proposed by the applicant into a fiber length in the above range. That is, Japanese Patent Application No. 7-2060.
As proposed in No. 27, alumina containing silica (SiO ₂ ) is spun, and thereafter, a spun alumina consisting of only fibrous materials is obtained except for granular materials or flakes. The alumina fiber of this spun product is subjected to a predetermined heat treatment to be subjected to dehydration and dechlorination of chlorine derived from the alumina raw material. Alumina constituting the alumina fiber thus obtained is a γ-phase, and the γ-alumina fiber is then converted into AlN fiber by nitriding. The obtained AlN fiber has an average diameter of 2 to 4 μm and a fiber length of several millimeters. When the fiber having this property is used as it is as a filler material for FRP, the fiber length is too long as described above, which is not preferable. Therefore, it can be obtained by pulverizing using an aluminum nitride pot mill or the like and adjusting the fiber length within the above range. The diameter of the AlN fiber of the present invention is not particularly limited,
A desired fiber diameter can be appropriately selected by adjusting the spinning nozzle hole diameter. Usually, the average fiber diameter is 2 to 10
Adjust to be μm.

In the fiber-reinforced insulating and high heat conductive plastic of the present invention, the amount of the AlN fiber to be mixed with the plastic is preferably 3 to 80% by volume, more preferably 10 to 40% by volume. If the amount is less than 3% by volume, the number of contact points of the AlN fibers decreases, and the improvement in thermal conductivity cannot be achieved. On the other hand, when the compounding amount exceeds 80% by volume, Al
It is not preferable because the plastic hardly penetrates into the N fibers. The above compounding and compounding of the plastic and the AlN fiber can be performed by a known method as in the conventional ERP. In addition, in order to enhance the adhesiveness to plastic as in the case of the conventional FRP, it is preferable to use AlN fibers that have been silane-treated with a silane coupling agent before compounding. As the silane coupling agent, an organic silane compound such as γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane can be used.

The fiber reinforced insulating and high thermal conductive plastic of the present invention uses high thermal conductivity, high density, non-porous AlN fiber as a filler material as described above, and its fiber length is specified. Therefore, it is easy to form a composite with plastic, and the AlN fibers are in contact with each other and have many contact points, so that the thermal conductivity is remarkably improved. For this reason, F has both the insulating properties of plastic and the excellent thermal conductivity of the filler material, and exhibits a composite function as a whole.
It can be obtained as RP. Further, at the time of molding such as extrusion molding of FRP, by controlling the AlN fiber to be oriented, the thermal conductivity of FRP can be given a direction. In addition, the fiber-reinforced insulating and high-thermal-conductivity plastic of the present invention is particularly excellent as a semiconductor encapsulant as described above because of its high thermal conductivity, but is also applicable to various applications. Is also possible.

[0015]

EXAMPLES The present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples. Examples 1 to 3 and Comparative Examples 1 and 2 (Production of Alumina Fiber) 10% by weight of a PVA (polyvinyl alcohol) solution 69 was added to 3200 g of a basic aluminum chloride solution having an Al ₂ O ₃ content of 23.5% by weight.
7 g and 116 g of colloidal silica having a concentration of 20% by weight were added, and the mixture was concentrated using a rotary evaporator until the viscosity at 20 ° C. became 35 poise to obtain a concentrated liquid. Then
Using a centrifugal spinning device having a diameter of 200 mmφ and a large number of holes with a diameter of 0.5 mm on the outer periphery, the obtained concentrated solution was rotated at a rotation speed of 20
Spinning was performed in a room replaced with dry air while rotating at 00 rpm to obtain a 25-mm thick matt-shaped alumina spun material containing SiO ₂ . Next, using a sieve having a mesh size of 0.5 μm, granules and flakes were removed from the obtained mat-like spun product, and only a fiber product was recovered. The recovered fiber material was further heated at 800 ° C. for 30 minutes to be dehydrated and dechlorinated. The crystal phase of the obtained alumina fiber was a γ-alumina phase.

(Production of AlN Fiber) The γ-alumina fiber produced as described above is accommodated in a silicon nitride boat and set in a heat treatment furnace, and ammonia gas is supplied at a flow rate of 300.
The LPG was heated at 1300 ° C. for 3 hours while flowing through the furnace at a flow rate of 10 cc / min. After the nitriding treatment, as a result of measurement with an X-ray diffractometer, the alumina fibers were all converted to AlN. The obtained AlN fiber was subjected to a heat treatment in air at 650 ° C. for 3 hours to be oxidized and decarburized.
The oxidized and decarburized AlN fibers were pulverized in an aluminum nitride ball mill such that the average fiber length after pulverization was about 200 μm and pulverized for about 5 minutes. Note that the obtained A
The average diameter of the 1N short fibers was 4 μm.

(Formation of FRP) After the AlN short fibers obtained as described above are subjected to silane coupling treatment, a predetermined amount is blended with an epoxy resin so as to have a blending amount substantially as shown in Table 1 and mixed. The mixture was stirred and defoamed to obtain a mixture. The obtained mixture is placed in a mold having a diameter of
Heat and cure with Al, disk-shaped Al about 1.5mm thick
N fiber reinforced epoxy composites were obtained respectively. In addition, Al
When the blending amount of the N fibers exceeded 80% by volume, the mixture was not uniform, and a molded composite having AlN fibers protruding from the surface even when heated and cured in a mold was obtained. The specific gravity of each of the obtained epoxy composites was measured, and the exact content of the AlN fiber was calculated. The results are shown in Table 1. Except for Comparative Example 3 in which a homogeneous composite was not obtained, the thermal conductivity of each epoxy composite was measured by a laser flash method. The results are shown in Table 1.

[0018]

[Table 1]

As is clear from the above Examples and Comparative Examples, when the blending amount of AlN fiber is 1.9% by volume, the thermal conductivity does not change as compared with the epoxy resin, but about 3% by volume or more. It turns out that it rises. By these, A
It is estimated that the thermal conductivity is increased or decreased due to the increase or decrease of the contact point of the 1N fiber.

Examples 4 to 6 and Comparative Examples 4 to 5 The AlN fibers produced in the same manner as in Example 1 were ball milled for 30 seconds to have the average fiber length shown in Table 2. Except for 2 minutes, each AlN short fiber was obtained in the same manner. An epoxy composite was formed in the same manner as in Example 1, except that the obtained AlN fibers had almost the same blending amount. Similarly, the specific gravity of the obtained epoxy composite was measured to calculate the blending amount of the AlN fiber, and as a result, as shown in Table 2, all were about 20.6% by volume. Further, the thermal conductivity was measured in the same manner. The results are shown in Table 2.

[0021]

[Table 2]

As is clear from the above Examples and Comparative Examples, it is found that if the fiber length is less than 50 μm and 15 μm, the thermal conductivity cannot be improved. On the other hand, in the case of 1 mm longer than 800 μm, compounding was not possible even with a compounding amount of about 20% by volume, and a smooth composite was not obtained.

[0023]

The fiber reinforced insulating and high thermal conductive plastic of the present invention is obtained by blending AlN fiber having the highest thermal conductivity among ceramics as a filler material as a plastic. Since it is predetermined, it can be easily and uniformly mixed with the plastic and homogeneously compounded as a whole, and as a whole, it has both excellent properties of plastic insulation and thermal conductivity of AlN. Therefore, it can be particularly suitably used as a semiconductor sealing material, and can be adapted to various uses. In addition, when the semiconductor material is suitably used as a sealing material for a semiconductor, the reliability of semiconductor quality assurance can be improved without deteriorating semiconductor quality stably for a long period of time.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 101/12 C08L 101/12

Claims (6)

[Claims] 1. A fiber-reinforced insulating and high heat conductive plastic comprising an aluminum nitride fiber having an average fiber length of 50 to 800 μm. 2. The compounding ratio of the aluminum nitride fiber is 3
The fiber-reinforced insulating and high thermal conductive plastic according to claim 1, wherein the content is from about 80% by volume. 3. The fiber reinforced insulating and high thermal conductive plastic according to claim 1, wherein said aluminum nitride fiber is obtained by grinding aluminum nitride long fiber with an aluminum nitride pot mill. 4. The aluminum nitride fiber is obtained by pulverizing amorphous alumina long fiber with an alumina pot mill and then nitriding.
The fiber reinforced insulating and high thermal conductive plastic described. 5. A fiber reinforced insulating and high thermal conductive filler material comprising aluminum nitride fibers having an average fiber diameter of 2 to 10 μm and an average fiber length of 50 to 800 μm. 6. The fiber-reinforced insulating and high thermal conductive filler material according to claim 5, wherein the aluminum nitride fiber is obtained by grinding aluminum nitride long fiber with an aluminum nitride pot mill.