JP2926888B2 - Resin composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyester-based liquid crystalline polymer composition containing an inorganic filler, which has excellent fluidity during molding, and also has excellent linear expansion coefficient and mechanical properties. Yes, electrical and electronic components,
It is used as an encapsulant for automobile parts and ICs (LSI, IC, hybrid IC, etc.).

[Conventional technology and issues]

A so-called thermotropic liquid crystalline polymer capable of forming an anisotropic molten phase has excellent mechanical properties, linear expansion coefficient,
Because of its extremely good fluidity in addition to dimensional accuracy and chemical resistance, it has been applied and developed to precision parts, audio-related parts, electric and electronic parts, and the like.

In particular, in the case of injection molded products, inorganic fillers such as glass fiber, carbon fiber, mica, talc, glass beads, and silica are used in combination to control physical properties in the flow direction and the direction perpendicular to the flow. .

Semiconductor elements such as ICs and LSIs are sealed to ensure electrical insulation, moisture resistance, and the like, and the sealing method is generally ceramic sealing and plastic sealing using a resin.

When the semiconductor element is sealed with resin, the stress generated by the difference in the coefficient of linear expansion between the silicon chip and the resin causes deformation of A1 wiring and bonding wires, disconnection or cracks in passivation, and changes in electrical characteristics. It causes deterioration of moisture resistance. Therefore, a method of adding an inorganic filler to the resin and reducing the difference in linear expansion coefficient from the silicon chip has been considered for the purpose of reducing these stresses.

Here, in order to reduce the linear expansion coefficient difference by adding an inorganic filler to the resin, it is more effective to increase the addition amount, but as the filler addition amount increases, the melt viscosity of the resin composition increases. Since the flowability increases and the flowability decreases, adversely affecting the moldability, a sealing material resin composition having sufficient linear expansion coefficient and moldability has not yet been obtained.

[Means for solving the problem]

The present inventors, when encapsulating a semiconductor element such as an IC or an LSI with a plastic using a resin, use a particle having a specified particle size, a particle size distribution and a form of the inorganic filler as an inorganic filler to be added to the resin. By using a polyester-based liquid crystalline polymer having a specific structural unit and a specific melt viscosity as a resin, the entire resin maintains high fluidity and has good moldability, and furthermore, the sealing material after molding is used. The inventors have found that the coefficient of thermal expansion can be reduced to hardness, and have reached the present invention.

An object of the present invention is to provide a resin composition having excellent fluidity and excellent linear expansion coefficient and mechanical properties.

That is, the present invention Containing at least 50 mol% of the resin composition at 320 ° C.
A polyester-based thermotropic liquid crystalline polymer having a melt viscosity at 0 ³ sec ^-1 of 3,000 poise or less is mixed with an inorganic filler satisfying the following conditions in an amount of 15 to 85 vol% based on the entire resin composition.
It is a resin composition characterized by being blended.

The inorganic filler has an average particle diameter of 0.05 to 150 μm, and (a) particles composed of two or more groups having different average particle diameters; Are spherical particles smaller than 5 μm, (c) particles having an average particle size larger than (b) and larger than 2 μm are crushed particles, and (d) two particles having an average particle size close to each other. The minimum particle size in the range defined by the standard deviation value of the particle size distribution of the group of particles having a large average particle size, and the maximum particle size in the range defined by the standard deviation value of the particle size distribution of the particle group having a small average particle size. (E) the ratio of the volume of the particle group having the larger average particle size to the total volume of the two particle groups having the average particle size close to each other is 20 to
95 vol%.

 Hereinafter, the present invention will be described in detail.

In the present invention, as a resin Containing at least 50 mol% of the resin composition at 320 ° C.
A polyester-based thermotropic liquid crystalline polymer having a melt viscosity at 0 ³ sec ^-1 of 3,000 poise or less is used. here,
Thermotropic liquid crystalline polymer is a polymer that can take a liquid crystal state when melted.

Examples of such a thermotropic liquid crystalline polymer include an aliphatic aromatic copolymerized thermotropic liquid crystalline polymer and a wholly aromatic copolymerized thermotropic liquid crystalline polymer.

However, the liquid crystalline polyester of the present invention It is essential that the components contain at least 50 mol% of the resin composition.

By maintaining a high fluidity by blending a polyester-based thermotropic liquid crystalline polymer containing 50 mol% or more of the resin composition of the structure with an inorganic filler described below,
And not only greatly reduces the coefficient of linear expansion (α _T ),
Α in the direction of flow (MD) and the direction perpendicular to this (TD)
_T balance is improved.

Even if it ’s a liquid crystalline polymer, Structure not preferred when less than 50 mole percent of the resin composition deteriorates flowability, MD and alpha _T of each alpha _T balance poor or TD in the TD was large or the. Α _{T of} TD
Is preferably 3.0 × 10 ⁻⁵ / ° C. or less, and the ratio of α _{T in} TD / MD is preferably 2 or less in the sense of reducing anisotropy.

Examples of thermotropic liquid crystalline polymer having a structure containing 50 mol% or more of the resin composition include (1) X7G obtained from polyethylene terephthalate and paraacetoxybenzoic acid.
And X7H (Eastman Kodak Company) polyester (JP-B-56-16016) or (2) Poly (ethylene terephthalate) and parahydroxybenzoic acid are reacted with acid in the presence of an acylating agent to form a copolymerized oligomer, followed by polymerization. Copolymerized polyester obtained by The content is 50 mol% or more of the resin composition)
-186527, Japanese Patent Application No. 59-42270) (3) Terpolymer of p-hydroxybenzoic acid / bisphenol / terephthalic acid (composition ratio of each 50:25:25) (this is a trade name of Econol or Zyder) (Commercially available) (4) 75: 2 p-hydroxybenzoic acid and 2-oxy-6-naphthoic acid
5 things. (This is marketed under the brand name Vectra.)

Among these liquid crystalline polymers Is at least 50 mol%, preferably 60 mol%, based on the resin composition.
Mol% or more, more preferably 65 mol% or more. If this condition is satisfied, there is no need for the above example. Also,
A part of the main chain may be substituted with an amide group, an ether group, a ketone group, an imide group, a carbonate group, or the like, but is preferably not substituted.

Further, it is necessary that the liquid crystalline polyester itself has good fluidity.

That is, the melt viscosity at 10 ³ sec ^-1 at 320 ° C. is 3000 poise or less.

If you make the inorganic filler becomes higher the viscosity, fluidity although it is natural to deteriorate unfavorably poor balance of the respective alpha _T MD and TD.

Furthermore, the melt viscosity at 10 ³ sec ^-1 at 320 ° C. is preferably 2500 poise or less, more preferably 1500 poise or less, and 10
It is most preferably at most 00 poise.

Any liquid crystalline polyester which satisfies these two conditions may be used. In particular, the above (2) and (4), and most preferably (2) may be used.

The inorganic filler particles used in the present invention include silica, alumina, titania, zirconia, titanium silicate, aluminum silicate, lithium aluminum silicate, magnesium aluminum silicate, aluminum titanate, and aluminum nitride. , Silicon nitride devices and the like, but are not limited thereto. Also, two or more fillers can be used.

Since the inorganic filler is used for the purpose of lowering the coefficient of thermal expansion by kneading with the resin, the filler itself is preferably low in coefficient of thermal expansion, and silica is most preferable in this regard. Further, for the purpose of preventing corrosion of aluminum wiring and occurrence of soft errors, it is desirable that the purity is high, especially the impurity elements such as chlorine, uranium and thorium are small.

In the resin composition of the present invention, the particles have an average particle size of 0.05 to 150 μm.
Are used. This has an average particle size of 0.05 μm
If smaller, the specific surface area of the particles is large, so that aggregation is likely to occur. Therefore, it is not preferable because a resin composition filled with the particles at a high density cannot be obtained.Moreover, particles having an average particle size larger than 150 μm are used. This is because when particles having different particle diameters are mixed, kneaded with a resin, and melt-molded, the particles are easily separated from particles having other particle diameters, so that uniform mixing and uniform molding become difficult.

The inorganic filler used in the present invention must satisfy the following conditions.

(A) It is composed of two or more groups of particles having different average particle sizes.

(B) The particles constituting the particle group having the smallest average particle diameter in the particle group are spherical particles having an average particle diameter of less than 5 μm, preferably 2 μm or less, more preferably 1.0 μm or less.

(C) Particles having an average particle size larger than (b) and larger than 2 μm are crushed particles.

(D) In two particle groups having an average particle diameter close to each other, a minimum particle diameter in a range defined by a standard deviation value of the particle diameter of a particle group having a large average particle diameter and a particle diameter of a particle group having a small average particle diameter The ratio of the maximum particle size in the range defined by the standard deviation value of the particle size is 2 or more, and preferably 5 or more.

(E) The ratio of the volume of the particle group having the larger average particle size to the total volume of the two particle groups having the average particle size close to each other is 20 to
It is in the range of 95 vol%, more preferably 50 to 90 vol%.

The conditions (a) to (e) will be further described. (A) The number of particle groups having different average particle sizes is appropriately selected in consideration of the particle size distribution of each particle group, the particle size ratio between the particle groups, and the like. Is done.

In the case of particles having an average particle size in the range of 0.05 to 150 μm, the particle size ratio of adjacent particles defined in (d) is 2, and each particle group has a uniform particle size (ie, no particle size distribution). )), Theoretically up to 12 groups of particles can be included. However, when the particle population has a particle size distribution, for example, when the normalized standard deviation index (X) of the particle size distribution is 1.2, it is theoretically possible to include up to 8 particle populations.

When (X) = 1.2 in the particle size distribution and the particle size ratio defined in (d) is 5, up to four groups can be theoretically possible.

The “normalized standard deviation index (X)” is a value defined by X = 1 + σ / a where a is the average particle diameter of the particle group and σ is the standard deviation. Is a numerical value that converges to 1 as the particle size distribution becomes narrower.

(B) The average particle diameter of the group of particles having the smallest average particle diameter is 5 μm.
The smaller spherical particles are considered to increase the filler content by being present in the particle gaps of the other large particle groups and increase the slipperiness between the large particles in the resin composition. When the particle size is larger than 5 μm, it is difficult to enter the gap between the large particles.

(C) Particles having an average particle size larger than (b) and larger than 2 μm are crushed particles.

(D) A particle group having a minimum particle size and a small average particle size in a range defined by the standard deviation value of the particle size distribution of a particle group having a large average particle size in two particle groups having an average particle size close to each other. If the ratio of the maximum particle size in the range defined by the standard deviation value of the particle size distribution is smaller than 2, it is not preferable because small particles hardly enter voids formed between large particles.

(E) When the volume of the particle group having a large average particle diameter is less than 20 vol% with respect to the total volume of two particle groups having an average particle diameter close to each other, large particles are scattered while small particles are packed. On the other hand, if the volume of particles having a large average particle size exceeds 95 vol%, the volume ratio of small particles filling the voids becomes smaller than the volume ratio of the voids generated between the large particles. Is bad.

In addition, it is generally desirable that the particle size distribution of each particle group be relatively narrow, for example, a normalized standard deviation index of 2 or less, more preferably 1.5 or less, and most preferably
1.2 The following are selected, but need not be limited in each specific situation.

That is, when the particle size ratio under the above condition (d) is considerably large, that is, when there is a considerable difference between the particle sizes of the seed portions of the two particle groups, the particle size distribution of each particle group is relatively wide. In both cases, the small particles may be sufficiently filled in the gaps between the large particles, and the problematic voids may not be generated. Accordingly, the particle size distribution of each particle group may be appropriately selected in consideration of the particle size ratio under the condition (d) according to each case.

If the inorganic filler satisfying the conditions of particle shape, average particle size, particle size distribution and average particle size ratio of particles as described above and volume ratio of particles is kneaded with resin and other additives, average particle size By efficiently filling the particles having a small average particle diameter into the gaps of the particles having a large diameter, it is possible to increase the amount of the inorganic filler added to the entire resin composition while maintaining a high fluidity. .

In the resin composition of the present invention, the filler is 85% of the resin composition.
It is possible to mix up to volume%.

Further, even when the amount of the filler is small, it is possible to obtain a resin composition having the same viscosity as the resin composition obtained by the conventional method and having a lower viscosity than the resin composition.

 In addition, the compounding amount is calculated by the following formula [I].

W particles: compounding weight of filler [g] ρ particles: density of filler [g / cm ³ ] W resin: compounding weight of resin (including additives) [g] ρ resin: density of resin (including additives) [G / cm ³ ] An inorganic filler satisfying the conditions of the particle shape, average particle size, particle size distribution, average particle size ratio of particles and volume ratio of particles as described above has a specific structure. However, when kneading with a polyester-based thermotropic liquid crystalline polymer having a specific viscosity, highly fluid particles can be efficiently filled by efficiently filling particles having a small average particle size in the gap between particles having a large average particle size. It is possible to increase the amount of the inorganic filler added to the entire resin composition while maintaining the above.

The inorganic filler may be mixed with the resin as it is, but the use of a surface treatment agent is preferred in terms of fluidity and mechanical properties.

As the surface treatment agent used, a silane coupling agent is preferable, and in particular, an epoxy-containing silane coupling agent,
Amine-containing silane coupling agents are preferred. Of these, amine-containing silane coupling agents are preferred from the viewpoint of fluidity.

The content of the inorganic filler is 15 to the entire resin composition.
It is blended to be 85vol%. When less than 15vol%,
The coefficient of linear expansion tends to increase (in both the flow direction and the direction perpendicular thereto), which is not preferable.
If it exceeds 85vol%, the fluidity will be extremely deteriorated,
It is not preferable because it tends to disappear.

In particular, it is preferable to mix 20 to 75 vol%, more preferably 25 to 70 vol%.

Such a resin composition has a low coefficient of linear expansion and good heat resistance, and can be used as a resin composition having high fluidity and good moldability.

As a general method for adjusting the resin composition of the present invention as a molding material, after dry-blending the raw material composition components selected in a predetermined blending ratio with a Henschel mixer or the like, kneading with a twin-screw extruder or the like, It is preferable to pelletize.

However, when two or more groups of particles having different average particle diameters including the fine particles of 5 μm or less described above are added to and mixed with the resin in a dry state as described above, the dispersion of the particles in the resin, particularly the fine particles Is not sufficiently dispersed and uniform mixing is difficult.
Further, even if two or more groups of particles including fine particles are to be mixed in a dry state in advance, in the dry state, the fine particles are extremely agglomerated and the particles are not sufficiently mixed uniformly. Also, wet mixing in a solvent such as benzene and toluene was attempted, but uniform mixing was not possible, and even if the heterogeneous mixture was mixed with the resin, the dispersion and mixing of the particles in the resin were not sufficient. Therefore, it is difficult to exhibit the above-mentioned effects of high filling property of particles and slippage between particles.

This point can be solved by dispersing and mixing the inorganic particles in the polar liquid, and then blending it with the resin to obtain a resin composition uniformly dispersed in the filler containing the fine particles.

Examples of the polar liquid used include water, alcohols such as methanol, ethanol, and isopropanol; glycols such as ethylene glycol and propylene glycol; dimethylformamide, and dimethyl sulfoxide. Any polar liquid that can be dispersed in water can be used. However, the polar solvent used may be restricted depending on the use of the obtained resin composition. For example, when a resin composition is used for a semiconductor sealing material, a halogen-containing polar liquid is not preferable.

The amount of the polar liquid to be used may be any amount in which the filler particles can be satisfactorily dispersed, and the volume% of the filler particles to the sum of the filler particles and the polar liquid is 5 to 85%, preferably about 10 to 60%. .

In order to disperse and mix the filler particles in the polar liquid, it is preferable to use a usual dispersing or mixing means such as a ball mill or an ultrasonic disperser.

The dispersion and mixing of two or more particle groups may be performed by first dispersing each particle group sufficiently in a polar liquid and then mixing each particle group dispersion in a slurry state, or two or more particle groups. May be added to the polar liquid and then dispersed and mixed.

Filler particles dispersed and mixed in a polar liquid are usually
After removing the polar liquid and drying, it is blended as shown in the figure according to the method described above.

When the resin can be dissolved in the polar liquid used for the dispersion and mixing of the filler particles, the filler particles are dispersed and dissolved in the mixed polar liquid slurry, and the resin is further dissolved and thoroughly mixed.
The resin composition can also be obtained by evaporating and removing the polar liquid.

In any case, when the polar solvent is removed, for example, by agitation or the like, separation between particles (because there is a risk of separation due to a difference in sedimentation due to a difference in particle size) and separation of resin and particles. Care must be taken to prevent this from happening.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples unless departing from the gist thereof.

<Resin A> Polyethylene terephthalate oligomer (η _inh = 0.1
1dl / g) 19.2 kg (100 mol) and p-hydroxybenzoic acid 5
5.2 kg (400 mol), 40.8 kg of acetic anhydride and 22.32 g of stannous acetate were charged into a polymerization vessel equipped with a stirrer, and after purging with nitrogen three times, the polymerization vessel was heated to 150 ° C. and stirred for 1 hour. ,
1 hour at 170 ° C and 1 hour at 240 ° C while distilling acetic acid.
Stirred for hours. Furthermore, the temperature of the polymerization tank was raised to 275 ° C., and the pressure was gradually reduced while distilling out acetic acid. After 30 minutes, the pressure was reduced to 0.15 mmHg. Next, the polymerization system was returned to normal pressure with N ₂ and zinc acetate dihydrate was added for 4 hours.
After the addition of 0.8 g, the mixture was stirred under a vacuum of 0.18 mmHg for 6 hours to complete the polymerization, extracted from the polymerization tank, and pelletized with a pelletizer.

The melt viscosity of the resin is 170 poise at 300 ° C. and 500 sec ⁻¹ .
It was observed that the material could flow in the range of 0 ° C. to 350 ° C. and exhibited liquid crystallinity in the same temperature range. This resin is referred to as resin A.

<Resin B> A pellet of a wholly aromatic polyester “VECTRA” A950 (trade name) marketed by Celanese Corporation is referred to as Resin B.

<Resin C> A liquid crystalline polyester composed of phenylhydroquinone and terephthalic acid is referred to as a resin C. Phenylhydroquinone diacytate and terephthalic acid were charged at a molar ratio of 1: 1. The temperature was gradually increased, and the temperature was increased at 380 ° C. After that, the system was depressurized and polymerized for about 1 hour to produce resin C.

<Resin D> A resin D is a liquid crystalline polyester composed of 2,6-naphthalenedicarboxylic acid, transstilbene dicarboxylic acid, and 1,4-butanediol (the molar ratio of each is 15:35:50). Resin D was synthesized from methyl ester of dicarboxylic acid and 1,4-butanediol based on USP 4,459,402.

Silica and its preparation <Example Silica I> Average particle size 0.9 μm, normalized standard deviation index (X)
90 g of monodispersed spherical silica of 1.05 was added to 215 g of ethanol (silica / ethanol volume ratio = 13/87), and dispersed in a ball mill for 24 hours. The slurry has an average particle size of 21 μm,
Crushed silica 510 with normalized standard deviation index (X) = 1.4
g and add slurry (silica / ethanol volume ratio = 50/5)
After that, the mixture was heated to 70 ° C. while stirring and mixing using a turbine blade type stirrer, and ethanol was volatilized and removed to obtain 600 g (silica I) of dry particles previously dispersed and mixed.
The minimum particle size in the range defined by the standard deviation of the particle size distribution of the crushed silica having an average particle size of 21 μm and X = 1.4 is 12.6 μm, and the particles of monodispersed spherical silica having an average particle size of 0.9 μm and X = 1.05. The maximum particle size in the range defined by the standard deviation of the diameter distribution is 0.
Since it is 945 μm, the ratio of the former to the latter is 13.3. The ratio of the volume of 21 μm to the total volume of those having an average particle size of 0.9 μm and 21 μm is 85% because the densities of the two are the same.

<Example Silica II> Monodispersed spherical silica 9 having an average particle size of 0.9 μm and (X) = 1.05
0 g and 510 g of crushed silica having an average particle size of 21 μm and (X) = 1.4 are prepared by dispersing in silica
I got II.

<Comparative Example Silica III> Average particle size 21 μm, normalized standard deviation index (X) =
A ground silica III of 1.4 was prepared.

<Example Silica IV> Average particle size 0.3 μm, normalized standard deviation index (X)
A slurry obtained by adding 95 g of monodispersed spherical silica having a density of 1.05 to 95 g of ethanol and dispersing it in a ball mill for 40 hours, and an average particle diameter
0.9 μm, 143 g of monodispersed spherical silica having a normalized standard deviation index (X) = 1.05 was added to 143 g of ethanol and dispersed in a ball mill for 40 hours.
Ground silica 612 with normalized standard deviation index (X) = 1.4
g, and mixed with a ball mill for 2 hours, heated to 70 ° C. to volatilize and remove ethanol, and further crushed with a ball mill for 2 hours to obtain previously dispersed and mixed dried particles 85
0 g was obtained. The maximum particle size in the range defined by the standard deviation value of the particle size distribution of monodisperse spherical silica having an average particle size of 0.3 μm and X = 1.05 is 0.315 μm, and the monodisperse spherical particle having an average particle size of 0.9 μm and X = 1.05. The minimum particle size in the range defined by the standard deviation value of the silica particle size distribution is 0.855 μm, the maximum particle size is 0.945 μm, the standard deviation value of the particle size distribution of the crushed silica having an average particle size of 21 μm and X = 1.4. The minimum particle size in the range defined by is 12.6 μm. Accordingly, the ratio of the minimum particle size in the range defined by the standard deviation value of the average particle size of 0.9 μm to the maximum particle size in the range defined by the standard deviation value of the average particle size of 0.3 μm is 2.
7 The ratio of the minimum particle size in the range defined by the standard deviation value of the average particle size of 21 μm to the maximum particle size in the range defined by the standard deviation value of the average particle size of 0.9 μm is 13.3.
It is. The ratio of the volume of 0.9 μm to the total volume of 0.3 μm and 0.9 μm is 60%.
%, The ratio of the volume of 21 μm to the total volume of 0.9 μm and 21 μm is 81.1%.

Examples and Comparative Examples These silicas were dry-blended with resin A or B so as to have the ratio (vol%) shown in Table 1, and then kneaded into pellets using a twin-screw extruder. The melt viscosity of the pellets was measured using a flow tester (trade name: CFT-500, manufactured by Shimadzu Corporation) to evaluate the fluidity.

In addition, the pellets are molded with a Nippon Steel 0.1oz injection molding machine, a part of the obtained molded product is cut out, and the coefficient of linear expansion (α _T ) is determined by the flow direction (MD) and the direction perpendicular to the flow direction (MD).
D) was measured. The linear expansion coefficient (α _T ) was measured using a thermomechanical analyzer (trade name: TMA-10, Seiko Denshi Co., Ltd.).

 The results are shown in Table 1.

[Effect of the Invention] According to the present invention, high fluidity can be obtained and / or the amount of the inorganic filler can be increased. Therefore, it is expected to obtain an encapsulant resin composition for ICs and the like, which has a high content of an inorganic filler and therefore has a low coefficient of thermal expansion and excellent heat resistance, and also has excellent fluidity and excellent moldability. The value is great.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-15262 (JP, A) JP-A-64-37045 (JP, A) JP-A-63-235337 (JP, A) (58) Investigation Field (Int.Cl. ⁶ , DB name) C08L 67/00-67/08 C08K 3/00-3/40 C08K 7/00-7/28

Claims (2)

(57) [Claims] (1) Containing at least 50 mol% of the resin composition at 320 ° C.
Polyester-based thermotropic liquid crystalline polymers having a melt viscosity at 0 ³ sec ^-1 of 3,000 poise or less
An inorganic filler consisting of particles having an average particle size of 0.05 to 150 μm satisfying the condition (e) is added to the resin composition in an amount of 15 to 85 vo.
1% by weight of a resin composition. (B) particles composed of two or more groups having different average particle diameters; (b) particles constituting the particle group having the smallest average particle diameter are spherical particles having an average particle diameter smaller than 5 μm; A particle group having an average particle size larger than 2 μm and larger than 2 μm is a crushed particle, and (d) a standard particle size distribution of a particle group having a larger average particle size in two particle groups having an average particle size close to each other. The ratio of the minimum particle size in the range defined by the deviation value to the maximum particle size in the range defined by the standard deviation value of the particle size distribution of the particle group having a small average particle size is 2 or more; The ratio of the volume of the particle group having a large average particle diameter to the total volume of the two particle groups whose particle diameters are close to each other is 20 to
95 vol%. 2. The resin composition according to claim 1, wherein the inorganic filler is silica.