JP3056300B2 - Resin composition for sealing electronic parts and electronic parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing material for electronic parts comprising a melt-processable polyester resin exhibiting optical anisotropy when melted. More specifically, the present invention relates to a resin composition for sealing electronic components having excellent fluidity and moisture resistance.

[0002]

BACKGROUND OF THE INVENTION Problems to be Solved by the Invention
For ICs, transistors, diodes, coils, capacitors, resistors, connectors, LSIs, etc., these are sealed with synthetic resin for the purpose of maintaining electrical insulation, protecting against external forces, and preventing changes in characteristics due to external atmosphere. That is widely done. Melt-processable polyesters capable of forming an anisotropic molten phase (hereinafter abbreviated as "liquid crystalline polyester") are extremely suitable for encapsulants because of their excellent properties such as low linear expansion coefficient, low molding shrinkage, and low elastic modulus. It is a suitable material. However, depending on the injection molding conditions, the encapsulating material for electronic parts using a high-molecular-weight liquid crystalline polyester may have insufficient internal flow due to insufficient flow during melting and shearing force during flow due to deformation of the element's gold wire, disconnection, etc. May damage the structure. Also,
A conventional electronic component sealing material made of a liquid crystalline polyester has a high hygroscopic property, and therefore, when used under high humidity conditions, current leakage due to absorbed moisture or element corrosion may occur. Such a problem has been attracting more and more attention as the structure of electronic component elements has become more complicated recently.

[0003]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have found that a specific liquid crystalline polyester is effective, and have reached the present invention.

That is, according to the present invention, the weight average molecular weight is 1,
000 to 25,000, including the structural units represented by the following (I) to (IV), wherein (I) is 50 to 85 mol%, (II) is 0.1 to 5 mol%, and (III) The present invention provides a resin composition for electronic component encapsulation, comprising as a main component a melt-processable polyester capable of forming an anisotropic molten phase having a resin content of 5 to 37 mol% and (IV) of 4.5 to 23 mol%. It is.

[0005]

Embedded image

The following are typical examples of raw materials for realizing each of the structural units (I) to (IV). The formula (I) includes p-hydroxybenzoic acid and its derivatives such as p-acetoxybenzoic acid, phenyl p-hydroxybenzoate, and methyl p-hydroxybenzoate. (II) Formula 6-hydroxy-2-naphthoic acid and its derivatives such as 6-acetoxy-2-naphthoic acid, 6-hydroxy-2-naphthoic acid phenyl ester, 6-hydroxy-2-naphthoic acid methyl ester and the like It is. Formula (III) is terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid and derivatives thereof, and terephthalic acid and derivatives thereof are particularly preferred. (IV) Formulas are hydroquinone, resorcinol, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenylpropane, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenylsulfone, and each compound thereof. And the like. Among them, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenylpropane and its derivatives are preferable, and 4,4'-dihydroxybiphenyl and its derivatives are particularly preferable. The amount of the structural unit (I) is 50 to 85 mol%, preferably 50 to 75 mol%, based on the whole. Beyond these ranges,
The melt viscosity increases, and workability is impaired. Structural unit (I
I) is from 0.1 to 5 mol% based on the whole, and preferably 1%.
４4 mol%. If the amount is less than this, the workability is impaired due to an increase in the melt viscosity, and if it is greater, the desired moisture resistance cannot be obtained. Structural unit (III) accounts for 5 to 37 mol% of the whole, and structural unit (IV) accounts for 4.5 to 23 mol% of the whole. By adjusting the difference between the ratio of the structural unit (III) and the structural unit (IV) to 0.5 to 15 mol%, a polymer having a desired molecular weight can be obtained.

[0007] Liquid crystalline polyesters suitable for use in the present invention generally have a weight average molecular weight of 1,000 to 25,000. 1,0
If it is less than 00, the formability is poor.
Undesirably, the object to be sealed is broken, deformed, etc. due to the shearing force during the flow. Preferably it is about 2,000-8,000. Such determination of molecular weight can be carried out by gel permeation chromatography and other standard methods without solution formation of polymers, for example by quantifying end groups by infrared spectroscopy on compression molded films. Alternatively, the molecular weight can be measured by using a pentafluorophenol solution and using a light scattering method. The polyester used in the present invention can be polymerized by a direct polymerization method or a transesterification method, and the polymerization is usually carried out by a melt polymerization method or a slurry polymerization method. In the polymerization, various catalysts can be used. Representative examples include dialkyltin oxides, diaryltin oxides, titanium dioxide, alkoxytitanium silicates, titanium alcoholates, and alkali and alkaline earth carboxylic acids. Metal salts, Lewis acids such as BF _{3 and} the like. The amount of catalyst used is generally from about 0.001 to 1% by weight, based on the total weight of the monomers,
0.01 to 0.2% by weight is preferred. A liquid crystalline polymer that exhibits optical anisotropy when melted is an essential element in the present invention in order to have both moisture resistance and easy processability. The property of the melt anisotropy can be confirmed by a conventional polarization inspection method using an orthogonal polarizer. More specifically, the melting anisotropy can be confirmed by using a Leitz polarizing microscope, melting a sample placed on a Leitz hot stage, and observing the sample at a magnification of 40 times in a nitrogen atmosphere. The polymers are optically anisotropic and transmit light when inserted between orthogonal polarizers. When the sample is optically anisotropic, polarized light is transmitted, for example, even in the state of a molten still liquid.

It is preferred that the resin composition for sealing electronic parts of the present invention contains an inorganic powder. The inorganic powder used in the present invention is not particularly limited as long as it is non-conductive, but preferably has a thermal conductivity of at least 10 W / m · K at 300 ° K. Examples of the inorganic powder having good thermal conductivity include oxides, nitrides, and carbides of metals or silicon. In this case, the elements are selected from the elements in the seventh to seventh columns of each of Groups II, III, and IV of the periodic table. As a specific compound, silicon oxide, particularly fused silica, beryllium oxide, magnesium oxide, aluminum oxide, thorium oxide, zinc oxide,
Silicon nitride, boron nitride, aluminum nitride, and silicon carbide can be given. These inorganic powders can be used alone or in combination of two or more. Among these, silicon oxide is preferred, and fused silica is particularly preferred. The inorganic powder is preferably in the form of powder, and the preferred average particle size is 1 to 100 μm, and more preferably 10 to 70 μm. The amount of the inorganic powder used is preferably such that the composition obtained matches the coefficient of linear expansion of the electronic component to be sealed, and is adjusted to obtain the required thermal conductivity and strength. There is a need to. Therefore, its use amount is from 20 to 80% by weight, preferably from 20 to 75% by weight, particularly
40-75% by weight is preferred.

The encapsulant of the present invention is further compounded with silicone for the purpose of lowering the distortion and stress of the resin at the time of molding and curing, and at the time of use with a sudden temperature change, and adhesion to the object to be sealed. can do. Here, silicone refers to silicone oil, silicone rubber, and silicone resin. These are polyorganosiloxanes, and have a side chain of dimethylpolysiloxane as a main component, for example, a part of a methyl group and / or
Or at least part of the main chain terminal is hydrogen, an alkyl group,
Aryl group, halogenated alkyl group, halogenated aryl group, amino-modified alkyl group, mercapto-modified alkyl group, epoxy-modified alkyl group, those having a carboxyl group-modified alkyl group, polyether-modified compounds, alcohol-modified compounds, ester-modified compounds It may be substituted with one or more kinds, or may have a crosslinked or grafted structure. The viscosity of the silicone oil used ranges from 0.5 to 1,000,000 cSt, preferably from 500 to 600,000 cSt. In view of the operability of extrusion and molding and the difficulty of exuding from the moldable resin, those having a viscosity of 1,000 to 100,000 cSt are particularly preferable.
The amount of silicone oil added is 0.1 to the total amount of the composition.
It is preferably 5% by weight, more preferably 0.5 to 3% by weight. In the present invention, the silicone rubber to be used is preferably in the form of a powder, and a millable silicone rubber in which an inorganic filler and a curing agent are kneaded with an organopolysiloxane having a high degree of polymerization and which is crosslinked by heat vulcanization, In addition, in the presence of a catalyst,
It is a silicone rubber or the like obtained by crosslinking at least one or more of organopolysiloxanes having a reactive group by heating, irradiation with ultraviolet light, or the like. Particularly preferred is an addition-type powdery silicone rubber which is crosslinked by a hydrosilylation addition reaction between an unsaturated group such as a vinyl group and -Si-H under a platinum compound catalyst. The granular silicone rubber has an average particle size of 0.1 to
100 μm is preferable, and 1-20 μm is particularly preferable.
belongs to. The addition amount of the silicone rubber is preferably 1 to 20% by weight, more preferably 2 to 15% by weight based on the total amount of the composition.
% By weight. In the present invention, the silicone resin used is a polyorganosiloxane having a three-dimensional highly network-like structure, preferably in the form of a powder,
It is preferably 0.1 to 100 μm, particularly preferably 1 to 100 μm.
It is 20 μm. The addition amount of the silicone resin is preferably 1 to 20% by weight based on the total amount of the composition.

The sealant of the present invention further contains additives such as inorganic fillers, dyes and pigments, release agents, antioxidants, heat stabilizers, reinforcing agents, hydrolysis stabilizers and the like which are conventionally used. May be blended. It is preferable to use various epoxy resins as the stabilizer.

[0011]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 As shown in Table 1, p-acetoxybenzoic acid (58 mol%)
-Acetoxy-2-naphthoic acid 4 mol%, terephthalic acid
20.2 mol%, 4,4'-diacetoxybiphenyl 17.5 mol%
And 0.05% by weight of potassium acetate based on the total charged amount were charged into a reactor equipped with a stirrer, a nitrogen inlet tube and a distilling tube, and the mixture was heated to 260 ° C. in a nitrogen stream for 1 hour. While distilling acetic acid from the reactor,
Heat to 300 ° C for 2 hours, then at 300-320 ° C for 1 hour, 3
The mixture was heated at 20-360 ° C for 1 hour, and acetic acid was distilled off under vacuum. Then, nitrogen was introduced and the mixture was cooled to room temperature. The obtained polymer showed optical anisotropy at 360 ° C. by observation with a polarizing hot stage microscope. Fused silica having an average particle size of 20 μm was mixed with this polymer at a ratio of 50% by weight, and the mixture was extruded using a normal extruder.
The pellet was formed at 320 ° C. according to a conventional method. Next, a DIP type 14-pin IC was formed by a so-called insert injection molding method. Table 1 shows the results of evaluation by the following measurement methods. The test method is as follows. (Number of broken gold wires of IC) Conduction test is performed on the molded product as shown in Fig. 1 to measure the breaking rate of gold wire 3 between chip 1 and lead frame 2 (the number of broken samples in 100 samples). did. (IC gold wire sweep) The sealed molded product was observed with soft X-rays, d / l in FIG. 2 was measured, and the average was calculated. (PCT failure rate) The sealed molded article was placed in an autoclave at 133 ° C. and 100% RH, and the IC failure rate after 100 hours (the failure rate of 100 samples) was measured. (Solder heat resistance) The solder heat resistance was determined by immersing the molded product in a solder bath at 280 ° C. for 30 seconds, and then observing the surface. When there was abnormality such as blisters, wrinkles, cracks, deformation, etc., it was evaluated as x, and when there was no abnormality, it was evaluated as ○.

Examples 2 to 4 The polymerization was carried out in substantially the same manner as in Example 1 except that the final heating temperature was set so as not to fall below the temperature range in which the polymer flows. The obtained polymer was evaluated in the same manner. Table 1 shows the results.

Comparative Examples 1 to 3 Polymerization was carried out in substantially the same manner as in Example 1 except that the final heating temperature was not lower than the temperature range in which the polymer flows. The obtained polymer was evaluated in the same manner. Table 1 shows the results.

[0015]

[Table 1]

[0016]

As described above, according to the resin composition for sealing electronic parts of the present invention, it is possible to obtain a sealing material which exhibits high fluidity during melting and has high moisture resistance.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a sealing molded product created in an example.

FIG. 2 is a schematic diagram showing an implementation state of a gold wire sweep test of an IC.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Chip 2 ... Lead frame 3 ... Gold wire 3a ... State of gold wire before molding 3b ... State of gold wire after molding

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 63/60 C08L 67/04 CA (STN) REGISTRY (STN)

Claims (9)

(57) [Claims] A weight average molecular weight of 1,000 to 25,000, including structural units represented by the following (I) to (IV), wherein (I) is 50 to 85 mol% and (II) is 0.1 to 5 mol%, (III) is 5 to 37 mol%, and (IV) is 4.5 to 23 mol% for sealing electronic parts mainly composed of a melt-processable polyester capable of forming an anisotropic molten phase. Resin composition. Embedded image 2. The resin composition for sealing electronic parts according to claim 1, wherein 20 to 80% by weight of an inorganic powder is blended with a melt-processable polyester capable of forming an anisotropic molten phase. 3. The inorganic powder has a thermal conductivity of 10 W / m · at 300 ° K.
The resin composition for electronic component sealing according to claim 2, which is a non-conductive inorganic powder having a K of not less than K. 4. The inorganic powder is a compound selected from oxides, nitrides and carbides of metals or silicon.
The resin composition for electronic component sealing according to the above. 5. The electron according to claim 2, wherein the inorganic powder is a compound selected from oxides, nitrides, and carbides of elements of the seventh to fourth columns of the periodic rules II, III, and IV, respectively. A resin composition for sealing parts. 6. An inorganic powder comprising silicon oxide, beryllium oxide,
Magnesium oxide, aluminum oxide, thorium oxide,
The resin composition for electronic component sealing according to any one of claims 2 to 5, which is one or more compounds selected from the group consisting of zinc oxide, silicon nitride, boron nitride, aluminum nitride, and silicon carbide. . 7. The electronic component sealing resin composition according to claim 6, wherein the silicon oxide is fused silica. 8. A resin composition for encapsulating electronic parts, wherein the composition according to claim 1 is further mixed with silicone. 9. An electronic component encapsulated with the composition according to claim 1. Description: