JPH0722943B2 - Pre-molded package - Google Patents

Description

TECHNICAL FIELD The present invention relates to a premolded package formed by an injection molding method, which is characterized in that a highly heat resistant thermoplastic resin composition is used as an injection molding material.

[Conventional technology and its problems]

For example, in 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 force, and preventing characteristic changes due to the external atmosphere. It is widely practiced.

However, recently, various demands have been made due to higher performance of the object to be sealed and changes in usage conditions.

One of the recent trends toward higher integration and larger size of ICs is attracting a great deal of attention, because the IC encapsulation resin has low distortion and low stress. Is required to reduce the damage that the IC receives. On the other hand, in terms of the usage of the sealing IC, the surface mounting technology, that is, the sealing IC is used so as to be directly in contact with the solder bath, so that the sealing material itself and the sealing material are not exposed even if exposed to a sudden temperature change. Stopped
It is necessary to make stress less likely to occur in the IC.

As a method to reduce the damage to this IC,
As shown in 1 and 2, elements such as ICs, transistors, and diodes are put in a case, that is, a pre-molded package formed by fixing a resin material on a substrate such as a lead frame, to reduce the damage of the element due to the external atmosphere. The method is widely practiced. Here, FIG. 1 is a diagram showing a state in which an element 3 such as a light emitting diode is mounted on a pre-molded package 2 fixed to a lead frame 1. Then, this is sealed with an epoxy resin so that light is emitted from the upper surface. The LED electronic parts etc. to be sent out are manufactured. In addition,
2 shows an example in which an electronic component is manufactured by mounting an element 3 such as an IC in a premolded package 2 fixed to a lead frame 1 and then sealing it with a lid 4.

In this case, the injection molding resin material used will not be required to have a low stress as required by the encapsulant, but it will have high strength, easy workability, good dimensional stability and solder heat resistance. Performance such as sex is required. In particular, the adhesion with the lead frame is to prevent the solder from entering the gap between the lead frame and the package when immersed in a high-temperature solder bath, and to prevent moisture from entering the gap between the lead frame and the package during use. It is a very important performance from the viewpoint of preventing invasion and insulation failure, and also from the purpose of preventing characteristic changes of elements such as ICs, transistors, diodes, etc., and as a synthetic resin currently used for this purpose Mainly uses epoxy resin, but its performance is not sufficient.

However, since a thermosetting resin such as this epoxy resin has a very long molding cycle and has a problem in workability, studies have been made on a thermoplastic resin having high heat resistance.

However, since high temperature heat resistant polyamide, polyphenylene sulfide, etc. are crystalline resins, they may cause post-shrinkage due to long-term use and cause cracks on the lead frame surface, which is an important performance with lead frame. However, there was a defect that the adhesiveness was insufficient and the airtightness was poor.

[Means for Solving the Problems]

In view of the above problems, the inventors of the present invention have made an earnest search and study to obtain a material having excellent properties as an injection molding resin material having high heat resistance for fixing to a substrate, and found that an anisotropic molten phase is formed. Melt processable polyester (hereinafter abbreviated as "liquid crystalline polyester") has excellent properties such as low linear expansion coefficient, low molding shrinkage and low elastic coefficient, and does not cause post-shrinkage and has excellent adhesion. It was found that it is a material that is extremely suitable for the above applications from the viewpoint that it is present. However, it has been found that the liquid crystalline polyester is still insufficient in view of the recent demand trend described above, and as a result of further intensive studies by the present inventor, it has been found that the liquid crystalline polyester is blended with silicone. As a result, it was found that a resin material having a significantly improved adhesion to the substrate can be obtained, and the present invention has been completed.

That is, the present invention provides a pre-molded package formed by fixing a resin material, which is a melt-processable polyester capable of forming an anisotropic melt phase by heating, and containing silicone, to a substrate by an injection molding method. .

The liquid crystalline polyester of the present invention is a melt-processable polyester and has a property that polymer molecular chains take a regular parallel arrangement in a molten state. The state in which the molecules are arranged in this manner is often called a liquid crystal state or a nematic phase of a liquid crystal substance. Such polymer molecules are generally elongated, flattened, fairly stiff along the long axis of the molecule, and have multiple chain extension bonds, usually in either coaxial or parallel relationship. Consists of.

The properties of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using a crossed polarizer. Specifically, the confirmation of the anisotropic molten phase was performed using a Leitz polarization microscope.
The sample placed on the hot stage is melted and placed under a nitrogen atmosphere.
It can be carried out by observing at double magnification. The polymers of the present application are optically anisotropic when transmitted between crossed polarisers, even if they are stationary, allowing polarized light to pass through.

Liquid crystalline polymers suitable for use in the present invention tend to be substantially insoluble in common solvents and therefore unsuitable for solution processing. However, as already mentioned, these polymers can be easily processed by conventional melt processing methods.

Liquid crystalline polyesters suitable for use in the present invention generally have a weight average molecular weight of about 1,000 to 200,000, preferably about 5,000.
It is 0 to 50,000, particularly preferably about 10,000 to 25,000.
On the other hand, suitable wholly aromatic polyesteramides generally have a molecular weight of about 1,000 to 50,000, preferably about 5,000 to 30,000,
For example, 15,000 to 17,000.

The above liquid crystalline polyesters and polyester amides also have an inherent viscosity (IV) of at least about 1.0 dl / g or more, for example, 2.0 to 10.0 dl / g when dissolved in pentafluorophenol at a concentration of 0.1% by weight at 60 ° C. Generally indicated.

As the constituent component of the polymer forming the anisotropic molten phase as described above, one or more of aromatic dicarboxylic acid and alicyclic dicarboxylic acid is used. 1 of aromatic diol, alicyclic diol and aliphatic diol One or more Aromatic hydroxycarboxylic acids One or more Aromatic thiol carboxylic acids One or more Aromatic dithiols, aromatic thiol phenols 1
One or more selected from aromatic hydroxyamines, one or more selected from aromatic diamines, and the like. That is, the polymer forming the anisotropic melt phase in the present invention is I) Polyester consisting mainly of II) Polyester consisting mainly of III) Polyester consisting mainly of IV) Polythiol ester consisting mainly of V) Mainly consisting of A polythiol ester consisting of VI) A polythiol ester consisting mainly of and VII) A polyesteramide mainly consisting of and VIII) A polyesteramide forming a anisotropic melt phase composed of a combination of polyesteramide mainly consisting of and and.

Furthermore, although not included in the category of the combination of the above components,
Aromatic polyazomethine is included in the polymer forming the anisotropic melt phase, and specific examples of such a polymer include poly (nitrilo-2-methyl-1,4-phenylene nitriloethylidyne-1,4-phenylene. Ethylidyne); poly (nitrilo-2-methyl-1,4-phenylene nitrilomethylidine-1,4-phenylenemethylidine); and poly (nitrilo-2-chloro-1,4-phenylene nitrilomethylidine-1, 4-phenylenemethylidine).

Furthermore, although not included in the category of the combination of the above components,
Polyester carbonate is included as a polymer forming the anisotropic molten phase. It consists essentially of 4-oxybenzoyl units, dioxyphenyl units, dioxycarbonyl units and terephthaloyl units.

Polymers forming an anisotropic melt phase which are particularly suitable for use in the present invention are mainly composed of the aromatic polyesters of I), II) and III) and the aromatic polyesteramide of VIII). It can be obtained by reacting an organic monomer compound having a functional group that forms a required repeating unit by the ester formation method of.

Preferred examples of compounds constituting them are 2,6-naphthalenedicarboxylic acid, 2,6-dihydroxynaphthalene and 1,4
-Naphthalene compounds such as dihydroxynaphthalene and 6-hydroxy-2-naphthoic acid, biphenyl compounds such as 4,4'-diphenyldicarboxylic acid and 4,4'-dihydroxybiphenyl, the following general formulas (I), (II) or ( III)
Compound represented by: (However, X: alkylene (C _{1 to} C ₄ ), alkylidene, -O
A group selected from —, —SO—, —SO ₂ —, —S—, and —CO— Y: — (CH ₂ ) _n — (n = 1 to 4), —O (CH ₂ ) _n O— (n
= 1 to 4)) p-hydroxybenzoic acid, terephthalic acid, hydroquinone, para-substituted benzene compounds such as p-aminophenol and p-phenylenediamine, and the substituted benzene compounds thereof (substituents are chlorine). , Bromine, methyl, phenyl, 1-phenylethyl), isophthalic acid, resorcin, and other meta-substituted benzene compounds.

Further, the liquid crystalline polyester used in the present invention may be a polyalkylene terephthalate which does not partially show an anisotropic melt phase in the same molecular chain, in addition to the above-mentioned constituents. In this case, the alkyl group has 2 to 4 carbon atoms.

Among the above-mentioned constituents, a compound containing one or more kinds of compounds selected from naphthalene compounds, biphenyl compounds and para-substituted benzene compounds as essential constituents is a further preferable example. Of the p-position-substituted benzene compounds, p-hydroxybenzoic acid, methylhydroquinone and 1-phenylethylhydroquinone are particularly preferable examples.

Incidentally, specific examples of the compounds as the constituents of the above I) to VIII) and specific examples of the polyester forming the anisotropic molten phase which is preferable for use in the present invention are described in JP-A-61-69866.
It is described in Japanese Patent Publication No.

Further, the liquid crystalline polyester of the present invention may be one in which other thermoplastic resin is supplementarily added to the extent of not impairing its purpose within the scope of the present invention.

The thermoplastic resin used in this case is not particularly limited, but examples thereof include polyolefins such as polyethylene and polypropylene, aromatic dicarboxylic acids such as polyethylene terephthalate and polybutylene terephthalate, and aromatic polyesters comprising diols or oxycarboxylic acids. , Polyacetal (homo or copolymer), polystyrene, polyvinyl chloride, polyamide, polycarbonate, ABS, polyphenylene oxide, polyphenylene sulfide, fluororesin and the like. Further, two or more kinds of these thermoplastic resins can be mixed and used.

The liquid crystalline polyester is a high-strength material in combination with its self-reinforcing effect due to its unique molecular arrangement, and has a small coefficient of linear expansion and a small molding shrinkage, so that there is little dimensional deviation. Despite its low melt viscosity and good flowability, it is 220
Has heat resistance up to ~ 240 ° C. Furthermore, it has good chemical resistance, weather resistance, and hot water resistance, is extremely chemically stable, and at the same time does not affect other materials, and is suitable as an injection molding material for outserts.

The present invention aims to further improve the performance by blending silicone with the liquid crystalline polyester while making use of such characteristics.

Silicone used in the present invention is a compound of organopolysiloxanes, the properties of which are silicone oil,
Any of silicone rubber, silicone resin and modified compounds thereof may be used, and one kind or two or more kinds may be used in combination.

The silicone oil is mainly composed of a linear dimethylpolysiloxane having a relatively low degree of polymerization, but has a side chain, for example, a part of a methyl group and / or at least a part of a main chain terminal, hydrogen, an alkyl group, Of aryl groups, halogenated alkyl groups, halogenated aryl groups, amino modified alkyl groups, mercapto modified alkyl groups, epoxy modified alkyl groups, carboxyl group modified alkyl groups, polyether modified compounds, alcohol modified compounds, ester modified compounds It may be substituted with one kind or two or more kinds.

The viscosity of the silicone oil used is 0.5-1,000,000 cSt
It is in the range, preferably 500 to 600,000 cSt. From the viewpoint of operability in extrusion and molding and difficulty in exuding from the resin after molding, a viscosity of 1,000 to 100,000 cSt is particularly preferable.

The silicone rubber used in the present invention means -H, -OH, -OR, at the main chain terminal and / or side chain of the organopolysiloxane. At least one kind of organopolysiloxane having at least one kind of reactive group such as the above is crosslinked by reaction.

Incidentally, the organopolysiloxane constituting the silicone rubber used in the present invention is, for example, a side chain of dimethylpolyloxane, a part of a methyl group and / or at least a part of the main chain terminal is an alkyl group other than the reactive functional group. , An aryl group,
One having a halogenated alkyl group, halogenated aryl group, amino modified alkyl group, mercapto modified alkyl group, epoxy modified alkyl group, carboxyl group modified alkyl group, polyether modified group, alcohol modified group, ester modified group, etc. Alternatively, it may be substituted with two or more kinds.

From the viewpoint of the reaction mechanism, it can be classified into three types of addition type, condensation type and radical type.

The addition type is, for example, with an unsaturated group such as a vinyl group under a platinum compound catalyst. It is a type that crosslinks by a hydrosilylation addition reaction between and.

The condensation type is a dehydration condensation reaction between silanols under a metal catalyst such as an acidic or basic substance or tin, a dealcoholization condensation reaction between silanols and alkoxysiloxanes, There is a type that crosslinks by dehydrogenative condensation between and silanol.

The radical type is a type that crosslinks by ultraviolet irradiation, generated Lycal recombination using a radical generator, an addition reaction, or the like.

In addition, there is a millable type silicone rubber in which an organopolysiloxane having a high degree of polymerization is kneaded with an inorganic filler and a curing agent, and is thermally vulcanized to be crosslinked.

In the present invention, an addition type silicone rubber that can obtain a highly pure powdery granular silicone rubber is particularly preferable. The powdery granular silicone rubber preferably has an average particle size of 0.1 to 100 μm, and particularly preferably 1 to 20 μm.

Further, the silicone resin is a polyorganosiloxane having a three-dimensional highly network structure, and is attached to a side chain of the main component methylpolysiloxane, for example, a part of the methyl group and / or at least a part of the main chain terminal. Hydrogen, alkyl group, aryl group, halogenated alkyl group, halogenated aryl group,
It is substituted with one or more of an amino-modified alkyl group, a mercapto-modified alkyl group, an epoxy-modified alkyl group, a carboxyl-modified alkyl group, a polyether-modified compound, an alcohol-modified compound and an ester-modified compound. May be.

In the present invention, the silicone resin is also preferably powdered, and preferably has an average particle size of 0.1 to 100 μm, particularly preferably 1 to 20 μm.

The blending amount of silicone in the present invention is 0.1 to 30% by weight based on the total amount of the resin material. In more detail,
The amount of silicone oil added is preferably 0.1 to 5% by weight, more preferably 0.5 to 2% by weight, and the silicone rubber is preferably 1 to 20% by weight, more preferably 2 to 15% by weight.
The silicone resin is preferably 1 to 20% by weight.

In the case of the resin injection molding material for a substrate of the present invention, it is not necessary to cure the silicone itself, and since it is not necessary to add it for the purpose of specifically reacting with the liquid crystalline polyester, a chemically inert material is used. preferable. In this case, it is preferable that these silicones are mixed nonuniformly when blended with the liquid crystalline polyester to form a so-called sea-island structure.

Next, an inorganic filler can be added to the liquid crystalline polyester resin material used in the present invention. As an inorganic filler, it is usually known to be added to liquid crystalline polyester for the purpose of improving mechanical / physical properties such as strength, rigidity and hardness, heat resistance, deformation resistance and various electrical properties. The inorganic filler of any shape such as fibrous, plate-like or powder-like is used depending on its purpose.

As the fibrous filler, glass fiber, asbestos fiber,
Inorganic chamber fibrous substances such as silica fiber, silica-alumina fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber and the like can be mentioned.

On the other hand, as the particulate filler, carbon black, graphite, silica, quartz powder, glass beads, milled glass fiber, glass balloon, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, wollast. Silicates such as knights, iron oxides, titanium oxides, zinc oxide, antimony trioxide, oxides of metals such as alumina, carbonates of metals such as calcium carbonate and magnesium carbonate, sulfates of metals such as calcium sulfate and barium sulfate. , Other ferrite, silicon carbide, silicon nitride,
Examples thereof include boron nitride.

Further, examples of the plate-like filler include mica, glass flakes and the like.

These inorganic fillers can be used alone or in combination of two or more. From the viewpoint of reducing the anisotropy of post-shrinkage, particularly preferred are glass fiber, glass flake, milled glass fiber, glass beads, talc, clay, kaolin, silica, alumina, potassium titanate fiber, carbon fiber,
Graphite fibers, various mica, wollastonite, calcium silicate, graphite, and other inorganic acid salts. Two or more of these substances can be used depending on the purpose.

The amount of such an inorganic filler used is preferably a composition that matches the linear expansion coefficient of the substrate to which the resin material obtained is fixed, and it is necessary to adjust the amount to obtain the required thermal conductivity. The content of the filler is preferably 20% by weight or more, more preferably 30% by weight or more, and 40% by weight based on the total amount of the resin material.
~ 85 wt% is a particularly preferred amount.

The inorganic filler used in the present invention may be used in combination with a known surface treatment agent depending on the desired physical properties.
Examples thereof include functional compounds such as epoxy compounds, isocyanate compounds, titanate compounds, and silane compounds. These compounds may be used after being subjected to a surface treatment in advance, or may be added at the same time when the material is prepared.

The resin material of the present invention may further contain additives such as inorganic fillers, dyes and pigments, release agents, antioxidants, heat stabilizers, reinforcing agents, hydrolysis stabilizers, etc., other than those usually used conventionally. .
As the stabilizer, it is preferable to use various epoxy resins.

The method of fixing the pre-molded package to the lead frame in the present invention is not particularly limited, but a so-called outsert molding method of fixing a resin material to the lead frame is preferable.

The pre-molded package of the present invention is an electric / electronic component,
A pressure sensor case, a surface wave filter case, which is a part for pre-molded packages that requires airtightness,
The effect is remarkable when applied to a crystal oscillator case, an LED case, a chemical VLSI case, or the like, and when applied to an electric / electronic component or the like in which an element is mounted on the case.

〔The invention's effect〕

The present invention is a pre-molded package using an injection molding material for fixing a resin to a substrate configured as described above, which has heat resistance and heat shock resistance, and the linear expansion coefficient of liquid crystalline polyester is extremely high. It is convenient because it is very small and is closer to a metal substrate such as a lead frame. In particular, a liquid crystalline polyester containing a filler such as glass fiber or inorganic powder has a small anisotropy, and the one having the same linear expansion coefficient in all directions can be obtained without being influenced by the flow of resin during molding.

Further, in the pre-molded package of the present invention, the post-shrinkage is reduced by the addition of silicone, the adhesion to the substrate is improved, and the reliability as a product is secured for a long period of time.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Examples 1 to 9 After mixing the glass fibers having the composition shown in Table 1, titanium oxide and silicone oils A to C with seven kinds of liquid crystalline polyester resins A to G described later, the mixture was dried at 300 ° C. in a usual extruder. After pelletizing according to the method, a premolded package having the shape shown in FIG. 1 was formed by the so-called outsert injection molding method. Also, an ASTM molded piece was molded. The cylinder temperature of the injection molding machine was 300 ° C. The measurement results are shown in Table 1.

The liquid crystalline polyester used in the examples has the following constitutional units.

The silicone oil used here is as follows.

Silicone oil A Dimethylpolysiloxane Viscosity 10000cSt Silicone oil B Dimethylpolysiloxane Viscosity 100000cSt Silicone oil C Dimethylpolysiloxane Amino-modified silicone oil having aluminoalkyl group in the side chain (amino equivalent
2000) The test method used for evaluation of viscosity 3500 cSt is as follows.

Ink immersion test An injection-molded product in which resin is fixed to the lead frame is immersed (room temperature x 1 hour) in a fluorescent ink liquid (PES fluorescent penetrant F-6A-SP manufactured by Eishin Chemical Co., Ltd.), and a metallic lead frame is obtained. The adhesion of the resin to the metal lead frame was evaluated by the presence or absence of ink invasion on the contact surface between the resin and the resin. It represents the number of 100 specimens that were found to be immersed.

Measurement of post-shrinkage rate A molded piece (80 mm x 80 mm x 3 mm) was annealed at 200 ° C for 3 hours, and then the dimension of the molded piece was measured with a three-dimensional measuring machine, and the reduction rate was calculated from the dimension before annealing.

a; Dimensions before annealing b; Dimensions after annealing Examples 10 to 11 Using only liquid crystalline polyester A, silicone rubber A,
Test pieces were prepared in the same manner as in Examples 1 to 9 except that B was used. The measurement results are shown in Table 2.

The silicone rubber A used here is dimethylpolysiloxane having a vinyl group, Of dimethylpolysiloxane having a particle diameter of 8% by means of an addition reaction in the presence of a platinum compound catalyst.
m) Silicone rubber. Further, the silicone rubber B is a silicone rubber in which a part of the methyl group of the silicone rubber A is replaced with an epoxy group.

Comparative Example 1 A test piece was prepared in the same manner as in Examples 1 to 9 after mixing glass fiber and titanium oxide only in the liquid crystalline polyester A. The measurement results are shown in Table 4.

Examples 12 to 13 Glass beads or milled fiber and silicone oil A were mixed only for liquid crystalline polyester A, and then premolded packages having the shape shown in FIG. 2 were produced in the same manner as in Examples 1 to 9. The measurement results are shown in Table 3.

Comparative Examples 2 to 3 Glass beads or milled fibers were mixed only with the liquid crystalline polyester A, and then premolded packages were prepared in the same manner as in Examples 12 to 13. The measurement results are shown in Table 4.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which an element is mounted on a premold package, and FIG. 2 is a perspective view showing a state in which the element is mounted on a premold package and then sealed with a lid. 1 ... Lead frame 2 ... Pre-molded package 3 ... Element 4 ... Lid

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Claims (11)

[Claims] 1. A pre-molded package formed by fixing a resin material, which is a melt-processable polyester capable of forming an anisotropic melt phase by heating, with silicone, to a substrate by an injection molding method. 2. The pre-molded package according to claim 1, wherein the content of silicone is 0.1 to 30% by weight based on the total amount of the resin material. 3. The pre-molded package according to claim 1, wherein the silicone is silicone oil and is added in an amount of 0.1 to 5% by weight based on the total amount of the resin material. 4. The silicone is a silicone rubber, and is blended in an amount of 1 to 20% by weight based on the total amount of the resin material.
Pre-molded package as described. 5. The pre-molded package according to claim 4, wherein the silicone rubber is a granular material having an average particle diameter of 0.1 to 100 μm. 6. The silicone is a silicone resin, and is blended in an amount of 1 to 20% by weight based on the total amount of the resin material.
Pre-molded package as described. 7. The pre-molded package according to claim 6, wherein the silicone resin is a powder or granular material having an average particle diameter of 0.1 to 100 μm. 8. The pre-molded package according to claim 1, wherein the resin material contains an inorganic filler. 9. The premold according to claim 1, wherein the premold package is a pressure sensor case, a temperature sensor case, a surface wave filter case, a crystal oscillator case, a chemical VLSI case or an LED case. package. 10. An electric / electronic component obtained by mounting an electric / electronic element on the pre-molded package according to claim 9. 11. Electric / electronic parts include a pressure sensor, a temperature sensor, a surface wave filter, a crystal oscillator, and a chemical VL.
The electric / electronic component according to claim 10, which is an SI or an LED.