JPH0798895B2 - Epoxy resin molding material - Google Patents

Description

TECHNICAL FIELD The present invention relates to an epoxy resin molding material for resin encapsulation. More specifically, the present invention relates to an epoxy resin molding material having excellent heat dissipation and moldability, which is used in a resin molded product for sealing electric parts and electronic parts.

(Prior Art) In recent years, in order to improve the performance and reliability of electric and electronic devices, and to improve productivity, resin encapsulation with plastic has come to be performed. These electric parts and electronic parts include, for example, transistors, diodes, capacitors, filters, rectifiers, resistors, coils, etc., and resin sealing means have been widely applied to these. Further, in this resin encapsulation, improvement of the power device rated output and shortening of the thermal fatigue life due to heat generation of the element become problems, so the encapsulating resin has high thermal conductivity such as crystalline silica or high-purity alumina. Addition of inorganic fillers has also been performed.

(Problems to be solved by the invention) However, in the conventional resin encapsulation, as the filling rate of the inorganic filler is increased in order to increase the thermal conductivity, the resin viscosity increases, and wire deformation, void unfilling, etc. Molding problems were unavoidable.

Therefore, it is the actual situation that the demands for higher performance and higher output of the power device cannot be met depending on the encapsulating resin molding material used so far.

The present invention has been made in view of the circumstances as described above, and solves the drawbacks of conventional resin molding compounds for sealing, and imparts characteristics such as high thermal conductivity, low viscosity, and high fluidity. It is an object of the present invention to provide a resin molding material which is capable of heat dissipation and has excellent moldability.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a method in which an epoxy resin is subjected to a reaction treatment with a lower alkyl alcohol or an alicyclic alcohol in a fluidized bed to obtain a surface SiOR (R represents a substituent). There is provided an epoxy resin molding material for resin encapsulation, which comprises a silicon nitride having a structure in which a lower alkyl group or an alicyclic alkyl group which does not have is formed is blended.

Further, the present invention, together with the phenol novolac resin in the epoxy resin, a part or all of the inorganic filler consisting of the above silicon nitride compounded 60 to 90 wt% of the total amount of the resin composition, and a silane coupling agent. Is also included as a preferred embodiment. Of course, other additives such as a cross-linking agent, a curing agent, a curing accelerator, a release agent, and a coloring agent may be added to this composition, if necessary.

There is no particular limitation on the type of epoxy resin used as the base resin of the present invention, and if it is a curable epoxy resin containing an epoxy group, bisphenol A type epoxy resin, novolac type epoxy resin, halogenated epoxy resin. A suitable material such as a glycidyl ester type epoxy resin can be used.

The silicon nitride to be added to this is the same as above on the surface.
It is characterized by having an OR group.

Explaining this point in more detail, although the inorganic filler and the resin are inherently poor in compatibility and cause thickening,
In the case of silicon nitride having a silanol (Si-OH) group on the surface, its composition greatly contributes to lowering the viscosity, and as compared with the state where the silanol group remains, it is reacted with alcohol as described above. It has been found that those having the surface SiOR structure are preferable from the viewpoints of moisture resistance and moldability (particularly burr characteristics) of the sealing resin. The present invention has been completed based on such knowledge.

Incidentally, when the silicon nitride is compounded with the resin, treatment with a well-known silane coupling agent, treatment with an organopolysiloxane, etc. is a means known so far (Japanese Patent Laid-Open No. 62-84162). JP-A-64-38424, JP-A-61-272268), all of the characteristics such as high thermal conductivity, low viscosity, and high fluidity in the addition to the encapsulating resin. The reality is that we have not been able to obtain satisfactory results for improvement.

This means that these conventional modifying means use well-known silane coupling agents and the like, but these treating agents have special substituents such as amino groups and unsaturated carbon groups. It is considered that the reason for the surface modification of silicon nitride is that it has unevenness in imparting homogeneity and characteristics, or imparts unfavorable surface activity, etc.

On the other hand, in the present invention, the SiOR structure has a lower alkyl group in which R has no substituent, for example, a lower alkyl group such as methyl, ethyl, propyl, butyl, or hexyl, or an alicyclic group such as a cyclohexyl group. The structure is limited to those consisting of an alkyl group, and since this structure is formed by the reaction treatment of the corresponding alcohol and silicon nitride in the fluidized bed, it is possible to impart significantly superior properties to the conventional ones. There is.

The particle size of silicon nitride is usually about 1 to 50 μm.

The alcohol for forming the SiOR structure of the present invention is not particularly limited in its kind, and as described above, it may be an alkyl alcohol or an alicyclic alkyl alcohol having a low boiling point and high reactivity corresponding to the definition of the R group. Preferably. Particularly, lower alcohols such as methanol, ethanol and propanol are exemplified as preferable ones.

The formation of the SiOR structure, as illustrated in the examples below,
It is realized as a reaction treatment of silicon nitride powder and alcohol in a fluidized bed. The fluidized bed is formed by introducing an inert gas such as nitrogen or argon, or air, which is a well-known reaction means, and further introducing an inert solvent. The alcohol can be supplied in liquid form or in gaseous form. Conditionally, the silicon nitride powder is in a fluidized state and the surface Si-
It is sufficient if OH is converted to SiOR.

By this treatment, the above-mentioned SiOR structure is uniformly formed on the surface of the silicon nitride powder.

Then, in the resin molding material of the present invention, silicon nitride which has been surface-treated with alcohol beforehand may be blended, and it is preferably blended in a proportion of 60 to 90% by weight with respect to the total amount of the resin. In this case, a part of the ratio may be used in combination with another inorganic filler. If necessary, glass fiber, calcium carbonate, clay, talc, aluminum hydroxide or the like can be used in combination. In any case, the above-mentioned silicon nitride is mainly compounded, but if this compounding amount is less than 60% by weight, the thermal conductivity is not sufficiently improved, and if the compounding amount exceeds 90% by weight, moisture resistance and moldability are deteriorated. It tends to decrease.

Further, in the present invention, it is preferable to blend a phenol novolac resin, but in addition to this, a crosslinking agent such as a phenol resin, a melamine resin, or an isocyanate, a curing agent such as an amine or an amide, an amine-based or phosphorus-based resin, if necessary. A system curing accelerator may be added.

Furthermore, a silane coupling agent is preferably blended in the present invention, and epoxy silane is exemplified as a suitable one.

The epoxy resin molding material of the present invention as described above can be used for actual use by mixing, kneading, pulverizing, or granulating the respective compounding components. The molding material is not only suitable for multi-cavity molding of electric and electronic parts such as transistors, diodes, capacitors, filters, rectifiers, resistors and coils by transfer molding and injection molding, but also for compression molding. It is applicable.

Hereinafter, the epoxy resin molding material of the present invention will be described in more detail with reference to examples.

Examples 1 to 5 Epoxy resin molding materials were manufactured by mixing and kneading the respective components according to the formulations shown in Table 1. The epoxy resin used was an O-cresol novolac resin having an epoxy equivalent of 220 and sp80 ° C., and the phenol novolac resin having a hydroxyl equivalent of 104 and sp87 ° C. was used.

For silicon nitride having a SiOR structure (average particle size 10 to 25 μm), 5% by weight of alcohol relative to silicon nitride is used, and the reaction is carried out in a fluidized bed (50 ° C. × 60 minutes to 100 ° C. × 30 minutes), followed by drying. The processed one was used.

The characteristics of this resin molding material were evaluated, and the results are shown in Table 1.

This evaluation was performed according to the following standard method.

(1) Melt viscosity 150 ℃, flow tester (nozzle diameter 1 × 2mm, load 30kg)
/ cm ² ).

(2) Spiral flow 170 ° C, evaluated according to EMMI.

(3) Wire deformation 16DIP standard aluminum TEG. After molding, the degree of deformation of Au wire (25 μm) is photographed by soft X-ray.

(4) Moldability Evaluation of appearance after 16DIP molding (voids, faintness, burrs) (5) Thermal conductivity 100φ, 25mm thick molded product was evaluated by QTM rapid thermal conductivity meter (Showa Denko).

As is clear from the results in Table 1, it was confirmed that a resin molding material having excellent heat conductivity and moldability was obtained as compared with Comparative Examples described later.

Comparative Examples 1 to 2 Example 1 without compounding silicon nitride having a SiOR structure
Molding materials were manufactured in the same manner as described above to evaluate the characteristics. The results are shown in Table 1, but the thermal conductivity and moldability were inferior to those of the examples.

Example 6 In Example 5, a silicon nitride having a surface SiOR structure of SiOC ₆ H ₁₁ from cyclohexanol was used, and its characteristics were evaluated in the same manner. The melt viscosity was 2600 (poise), the spiral flow was 50 (cm), and the thermal conductivity (× 10 ^-4 ) was 84. Both wire deformability and formability were good.

Comparative Example 3 In Example 1, the same silicon nitride was replaced with alcohol, and the following commercially available products were used and subjected to a stirring reaction treatment.

1) N-phenyl-γ-aminopropyltrimethoxysilane 2) Organopolysiloxane 3) -Aminopropyltriethoxysilane All of them have a high melt viscosity of 2800 (poise) or more and a spiral flow of 40 (cm) or less. And stopped at a low level. Therefore, in the wire deformation test, the wire was partially broken, and the occurrence of minute voids was confirmed.

Comparative Example 4 In Example 1, the silicon nitride which was agitated and not subjected to the reaction treatment in the fluidized bed was used.

Melt viscosity characteristics remained at 2500 to 2600 (poise) and spiral flow was not good at 42 to 43 (cm). Microvoids were also observed.

(Effect of the Invention) According to the present invention, as described in detail above, an epoxy resin molding material having good thermal conductivity and moldability is realized.

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Claims (4)

[Claims] 1. An epoxy resin is subjected to a reaction treatment with a lower alkyl alcohol or an alicyclic alcohol in a fluidized bed to form a surface SiOR (R represents a lower alkyl group having no substituent or an alicyclic alkyl group) structure. An epoxy resin molding material for resin encapsulation, which is characterized by containing the above silicon nitride. 2. An epoxy resin molding material obtained by blending an epoxy resin with a phenol novolac resin and an inorganic filler partially or wholly made of silicon nitride according to claim 1. 3. The epoxy resin molding material according to claim 2, which comprises 60 to 90% by weight of the total amount of the inorganic filler. 4. The epoxy resin molding material according to claim 1, which comprises a silane coupling agent.