JPH0369128A - Sealing of electronic component - Google Patents

Abstract

PURPOSE:To improve adhesion between a lead wire and a PPS resin under high temperature and high humidity by a method wherein the lead wire is coated with one or more kinds of heat-resistant adhesives out of an aromatic polyimide, an aromatic polyamideimide, an aromatic polyether imide and a bismaleimide resin and, then, it is sealed with the PPS resin containing an inorganic filler. CONSTITUTION:When an electronic component is sealed with a polyphenylene sulfide(PPS) resin, lead wires are coated with at least one kind of heat-resistant adhesive selected from an aromatic polyimide, an aromatic polyamideimide, an aromatic polyether imide and a bismaleimide resin, and are then sealed with the PPS resin containing an inorganic filler. For example, a 16-pin DIP-type lead frame is coated with a heat-resistant adhesive composed of an aromatic polyimide after this adhesive has been diluted with a solvent; after that, this assembly is dried at 120 deg.C and the solvent is removed. Then, the lead frame is set on a metal mold; it is sealed with and molded by a PPS resin which contains molten silica, a silane-based coupling agent and a glass fiber by using an injection molding machine exclusively for insertion use; thus obtaining a DIP-type IC sealed and molded product.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for sealing electronic components that improves the adhesion between a polyphenylene sulfide resin and a lead wire under high temperature and high humidity conditions.

<Prior Art> Polyphenylene sulfide resin (hereinafter referred to as PP5vIJ resin) has excellent chemical resistance, electrical properties, and mechanical strength, and is widely used as electrical/electronic parts and automobile parts.

In addition, in recent years, ppstm resin has been used for applications such as electronic component sealing, printed circuit boards, and electric wire coatings.
In these applications, excellent adhesion to metals is particularly required.

PP5v has improved adhesion to such metals! As J fat, a composition containing a silane coupling agent together with an inorganic filler (Japanese Unexamined Patent Publication No. 52-52958) is known.

On the other hand, in electronic component sealing applications, lead wires and PP
In order to prevent water from entering from the interface with the S resin, the lead wires are treated with a silane coupling agent in advance, and then the PP
A method of sealing with S resin (Japanese Patent Application Laid-Open No. 61-154135) and a method of applying epoxy adhesive to the lead wire in advance and then sealing with ppss resin (Japanese Patent Laid-Open No. 61-11324)
Publication No. 0) and the like are known.

<Problems to be Solved by the Invention> However, although the composition described in JP-A-52-52958 has improved moisture resistance of the sealing material itself,
Adhesion to the lead wire is insufficient.

Furthermore, although the sealing method described in JP-A-61-154135 has the effect of improving adhesion with lead wires, it cannot be said to have reached a practical level.
The method described in Japanese Patent No. 1-113240 has problems such as insufficient adhesion under high temperature and high humidity conditions due to the low heat resistance of the epoxy adhesive.

In view of the above circumstances, the inventors of the present invention have conducted intensive studies on methods for improving the adhesion between lead wires and PPS resin in electronic components under high temperature and high humidity conditions. The present invention was achieved by discovering that a method of applying PPS resin and then sealing with PPS resin is effective.

Means for Solving the Problems> That is, when sealing electronic parts with ppstet resin, the present invention uses aromatic polyimide, aromatic polyamideimide, aromatic polyetherimide, and bismaleimide resin for lead wires. The present invention provides a method for encapsulating electronic components, which comprises applying a heat-resistant adhesive of at least one selected type I:J, and then encapsulating it with a PPS resin containing an inorganic filler. .

The PPS resin used in the present invention is a polymer containing a structural formula of mol % or more, more preferably 90 mol % or more. If the repeating unit is less than 70 mol %, it is not preferable because heat resistance will be impaired.

In addition, PPS can have less than 30 mol % of its @ repeating units composed of repeating units having the following structural formula.

Among the PPS resins used in the present invention, (1)
Acid treated, (2) hot water washed or (3) organic solvent washed, or (4) sodium content 900p
pl or less is preferable because the effects of the present invention are further expressed.

These preferred PP5v below! The method for processing J fat will be explained.

First, the case of acid treatment is as follows.

The acid treatment method involves adding PP5lill to an acid or an aqueous solution of an acid.
For example, when using acetic acid, PPS resin powder is immersed in a pH 4 aqueous solution heated to 80 to 90''C. , a sufficient effect can be obtained by stirring for 30 minutes.Acid-treated PPS resin needs to be washed several times with water or warm water to physically remove residual acids or salts. It is.

The water used for washing is preferably distilled water or deionized water in the sense that it does not impair the effect of chemical modification of the PPS resin by acid treatment.

Next, the case of washing with hot water is as follows. In other words, when treating PPS resin with hot water, the temperature of the hot water is
It is important to set the temperature to 00"C or higher, more preferably 120"C or higher, even more preferably 150"C or higher, particularly preferably 170"C or higher. If it is lower than 100"C, the effect of the preferred chemical modification of the PPS resin will be small. Therefore, it is undesirable.

In order to achieve the desired chemical modification effect of ppsts fat by hot water washing, the water used is preferably distilled water or deionized water.The hot water treatment operation is as follows:
Usually, this is carried out by adding a predetermined amount of PPS resin to a predetermined amount of water, and heating and stirring the same in a pressure vessel. PP5t
! Regarding the ratio of I fat to water, it is preferable to have more water, but usually water II! , a bath ratio of 200 g or less of pps resin is selected.

Furthermore, since decomposition of terminal groups is undesirable, the treatment atmosphere is preferably an inert atmosphere to avoid this. Furthermore, the PPS resin that has undergone this hot water treatment is preferably washed several times with hot water in order to physically remove any remaining components.

Further, when washing with an organic solvent, the procedure is as follows.

The organic solvent used for cleaning the PPS resin is not particularly limited as long as it does not have the effect of decomposing the PP5vfJ fat, and examples thereof include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, 1,3-dimethylimidazolidinone, Nitrogen-containing polar solvents such as hexamethylphosphorus amide and piperazinones, dimethyl sulfoxide,
Sulfoxide/sulfone solvents such as dimethyl sulfone and sulfolane, getone solvents such as acetone, methyl ethyl getone, diethyl ketone, and acetophenone, ether solvents such as dimethyl ether pylether, dioxane, and tetrahydrofuran, chloroform, methylene chloride, trichloroethylene, Halogenated solvents such as ethylene dichloride, perchlorethylene, monochloroethane, dichloroethane, tetrachloroethane, perchloroethane, chlorobenzene, methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, phenol, cresol,
Examples include alcohol/phenol solvents such as polyethylene glycol and polypropylene glycol, and aromatic hydrocarbon solvents such as benzene, toluene, and xylene.

Among these organic solvents, N-methylpyrrolidone,
Particular preference is given to using acetone, dimethylformamide and chloroform. In addition, these organic solvents are
Used alone or in combination of two or more.

As a method of cleaning with an organic solvent, PP is added in an organic solvent.
There are methods such as immersing the S resin, and it is also possible to stir or heat as appropriate, if necessary.

There are no particular restrictions on the cleaning temperature when cleaning PPS resin with an organic solvent, and any temperature between room temperature and about 300°C can be selected. Although there is a tendency that the higher the cleaning temperature, the higher the cleaning efficiency, a sufficient effect can usually be obtained at a cleaning temperature of room temperature to 150°C.

It is also possible to wash under pressure in a pressure vessel at a temperature above the boiling point of the organic solvent. There is also no particular limit to the cleaning time. Although it depends on the cleaning conditions, in the case of batch cleaning, sufficient effects can usually be obtained by cleaning for 5 minutes or more.

It is also possible to wash continuously.

Contains ppsvIJ fat produced by polymerization 11! I! Although washing with a solvent alone is sufficient, in order to further exhibit the effects of the present invention, it is preferable to combine washing with water or hot water. Further, when a high-boiling water-soluble organic solvent such as N-methylpyrrolidone is used, it is preferable to wash with water or warm water after washing with the organic solvent, since the residual organic solvent can be easily removed. The water used for these washings is preferably distilled water or deionized water.

In addition, in order to fully express the effects of the present invention, the PPS resin used in the present invention has a sodium content of 900 pp.
It is preferably n or less.

PP with sodium content of 90 oppm or more] 11
As an effective means for reducing the sodium content of 1 fat to 900 ppn or less, treatments such as the above-mentioned acid treatment, hot water treatment, or washing with an organic solvent can be used.

The above-mentioned PPS II fat was treated with acid, hot water and washed with an organic solvent, and the sodium content was 90 op.
A pps of pn or less is only preferable in order to further express the effects of the present invention, and is by no means an essential condition of the present invention. In the present invention, any PP5t! 1 l fat can be used.

The aromatic polyimide used as a heat-resistant adhesive in the present invention is a polymer consisting of repeating units of the following formula (■), and the aromatic polyamide-imide used as a heat-resistant adhesive in the present invention is a polymer consisting of repeating units of the following formula It is a polymer consisting of (wherein, Ar is a tetravalent aromatic residue containing at least one carbon 6-membered ring, and R is a divalent aromatic and/or aliphatic residue) A suitable example is the following 'WI structure.

(Ar- is a trivalent aromatic group containing at least one carbon 6-membered ring, and R is the same as shown in ⑧.) Suitable examples include those of the following structural formula.

"HI 400" (Hitachi) "Semico Fine" 5P810 (East) m/n=70/
30 mol% ratio LL Torlon'' (Amoco) The aromatic polyetherimide used as a heat-resistant adhesive in the present invention is a polymer consisting of repeating units of the following formula (1), 1'Ultem'' (GE) (Ar- and R is the same as shown in the above formulas (■) and (0).) Suitable examples include those of the following structural formulas.

(wherein Ar'' is 2 containing at least one 6-membered carbon ring)
The valent aromatic group, R, is the same as that shown by ⑧. ) Suitable examples include those of the following structural formula.

The bismaleimide resin used as the heat-resistant adhesive in the present invention is a heavy kelimide resin (Rota-Boulin) consisting of the repeating unit of the following formula 〇. The adhesive is diluted with an organic solvent and sprayed by a method such as painting or screen printing.The coating thickness of the adhesive is preferably 1 to 5011 m, more preferably 2 to 30 m.

The lead wire coated with the adhesive is then heated and dried in order to remove the organic solvent and cure the adhesive.

The material for the lead wire of the electronic component in the present invention is not particularly limited, but any material that is a combination of various metals such as iron, nickel, copper, aluminum, tin, zinc, cobalt, and zirconium can be used.

In the present invention, the inorganic filler used in combination with the pps resin is a fibrous filler and/or a granular filler.
P51! It can be blended in an amount of 10 to 300 parts by weight per 100 parts by weight of I fat. If the blending amount is less than 10 parts by weight, the mechanical strength will be low and the coefficient of linear expansion will be large, making it easy for cracks to occur in the sealed molded product.
If it exceeds 1 part by weight, the melt viscosity becomes high and gold wire @ lines are likely to occur, which is not preferable.

Examples of such fibrous fillers include non-@ fibers and carbon fibers such as glass beads, alumina fibers, silicon carbide fibers, ceramic 1a fibers, asbestos fibers, gypsum fibers, and metal fibers.

Granular fillers include wollastenite, sericite, kaolin, mica, clay, bentonite, asbestos, talc, silicates such as alumina silicate, and metal oxides such as alumina, silicon chloride, magnesium oxide, zirconium oxide, and titanium oxide. Examples include carbonates such as calcium carbonate, magnesium carbonate, and dolomite, KM salts such as calcium sulfate and barium sulfate, glass beads, boron nitride, silicon carbide, and silica, which may be hollow. It is also possible to use two or more kinds of fillers in combination, and if necessary, the fillers can be pretreated with a silane-based and titanium-based coupling agent before use.

PP5l! ! The method for producing the composition consisting of fat and inorganic filler is not particularly limited and may be a general method. For example, by mixing each component together at room temperature using a ribbon blade type mixer or a drum type rotating mixer, melt-kneading is performed using a single-screw extruder, multi-screw extruder, or kneader, and then pelletized. can be manufactured.

The melt-kneading temperature is preferably 280 to 340'C, and 280 to 340'C.
If the temperature is less than 80"C, the melting of the PPS resin may become insufficient, so care must be taken.

The electronic components used in the present invention are not particularly limited as long as they can be considered in the concept of electronic components, but include, for example, □ capacitors, resistors, integrated circuits (ICs), transistors,
Examples include diodes, triodes, thyristors, coils, varistor connectors, converters, microswitches, and composite parts thereof.

There is no particular restriction on the method of side-stopping the lead wire using the composition comprising ppsvIJ resin and inorganic filler in the present invention.
A method in which the lead wire is fixed in a mold and molded by injection molding or transfer molding, or a method in which the lead wire is sealed under heat and pressure using a PPS resin composition that has been previously formed into a film shape. can be mentioned.

Furthermore, the electronic component obtained by the present invention can be treated with a peroxide such as a hydrogen peroxide solution after molding, or heat treated at a temperature below the melting point of the PPS resin.
S f! It is possible to increase the degree of crosslinking or crystallinity of J fat and improve its mechanical properties.

The present invention will be explained in more detail by giving Examples and Comparative Examples below.

Note that all parts and percentages shown in the examples are based on weight.

<Example> Reference Example 1 (Polymerization of PPS resin) Sodium sulfide 3.26 kf (25
(containing 40% water of crystallization), 4 g of sodium hydroxide, and 7.9 kIr of N-methyl-2-pyrrolidone (hereinafter referred to as NMP), and gradually added 20 kIr with stirring.
Distillate water heated to 5°C and containing 1.36 kl of water
．． 51 was removed. Remaining mixture 1, 3.75 kg (25° 5 mol) of 1,4-dichlorobenzene and N M
P 2 kg was added and heated at 265° C. for 4 hours.

The reaction product was washed 5 times with warm water at 70°C and incubated at 80°C for 2
After drying under reduced pressure for 4 hours, the melt viscosity was approximately 100 boids (310
Approximately 2 kg of powdered PPS resin was obtained at a shear rate of 1.000 s-1).

Next, 2 kg of the above PPS resin powder was poured into a pH 4 acetic acid aqueous solution 201 heated to 90°C, stirred continuously for about 30 minutes, filtered, and vP? The mixture was washed with deionized water at about 90°C until the pH of the mixture became 7, and dried under reduced pressure at 120°C for 24 hours to obtain a PPS resin dry powder. This ppst!
The total sodium content in I fat was 270 ppIm.

Reference Example 2 35 parts of the PPS resin powder obtained in Reference Example 1, 50 parts of fused silica (average particle size 12n+), 0.5 part of ureidopropyltriethoxysilane, and glass fiber (m 3a+L)
After tri-blending 15 parts, it was supplied to a 30 mm diameter twin-screw extruder, and melt-kneaded at a processing temperature of 270 to 320'C to form homogeneous melt-blended pellets, which were used in Examples.

Examples 1 to 4 Various adhesive solvents shown in Table 1 were diluted with 16
After applying it to a pin DIP type lead frame (material: 42 alloy), it was dried at 120° C. for 60 minutes to remove the solvent. The coating thickness of the adhesive was 5-10IJI11.

Next, set the above lead frame in a mold (temperature: 200°C) and insert it into an injection molding machine (temperature: 300-32°C).
At 0°C), seal molding was performed using a pellet obtained in Reference Example 2.
A 6-pin DIP type IC sealed molded product was obtained.

The obtained sealed product was subjected to a red ink test using the method described below, and the state of infiltration of the red ink between the lead frame and the resin was examined, and the results are shown in Table 1.

Red ink penetration test A 16-pin DIP type IC sealed molded product was immersed in red ink liquid, pressure crab 5 kgf/aaG, temperature: 80°C 1 hour = 1
After 6 hours of treatment, the degree of red ink penetration at the interface between the lead frame and the resin was expressed in (%) and evaluated.

As is clear from the results in Table 1, the sealing molded product obtained by the method of this example had significantly improved adhesion, and the degree of red ink penetration was 5% or less.

Comparative Example 1 An injection molding/red ink test was conducted in the same manner as in Example 1 using a lead frame to which no adhesive was applied. The results are also listed in Table ■.

Comparative Example 2 After applying an epoxy adhesive "Epicoat" 191 P (Yuka Shell Epoxy Co., Ltd.) to a lead frame, an injection molding/red ink test was conducted in the same manner as in Example 1. The results are also listed in Table 1.

Table 1 <Effects of the Invention> The electronic component obtained by the method of the present invention has excellent adhesion between the PPS resin and the lead wire under high temperature conditions.
It is extremely useful as a sealing component for ICs, transistors, capacitors, connectors, etc.

Patent application Daitoshi Co., Ltd.

Claims (1)

[Claims] When sealing electronic components with polyphenylene sulfide resin, at least one heat-resistant adhesive selected from aromatic polyimide, aromatic polyamideimide, aromatic polyetherimide, and bismaleimide resin is applied to the lead wire. and then sealing this with a polyphenylene sulfide resin containing an inorganic filler.