JP2969655B2 - Composition for sealing electronic parts - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electronic component sealing composition having improved moldability and weld strength, and an electronic component coated or sealed with the composition. .

<Prior Art> Polyphenylene sulfide resin (hereinafter abbreviated as PPS) is excellent in chemical resistance, heat resistance, electric characteristics and mechanical strength, and is widely used as electric parts and automobile parts.

On the other hand, in the field of resin compositions for electronic component sealing,
In place of conventional thermosetting resins, PPS resins, which are characterized by their material yield and molding speed, are attracting attention.Electronic component encapsulation in which this PPS contains fillers such as glass fibers, glass beads, silica and potassium titanate fibers. No. 4,337,182, Japanese Patent Publication No. 56-2790,
It has been proposed in Japanese Patent Publication No. 60-40188 and Japanese Patent Laid-Open No. 59-20910.

With the recent development of the electronics industry,
C, capacitors, diodes, transistors, etc. are being made thinner and smaller. For this reason, the encapsulant has high fluidity to the extent that bonding wires and elements are not damaged, and cutting / cutting of terminals of molded products. Practical strength (weld strength) that can withstand bending or chip mounting is required.

<Problems to be Solved by the Invention> However, in the case where the silica-containing PPS composition described in JP-B-60-40188 is used for IC encapsulation molding, the weld is formed immediately after the molded article is removed from the mold. There is a disadvantage that cracks occur in the part.

Also, U.S. Pat.No. 4,337,182 and JP-B-56-279.
In Japanese Patent Publication No. 0, mechanical strength is improved by kneading glass fiber with PPS. However, the strength of the weld portion of the molded product is insufficient, so that cracks occur when cutting / bending the terminal of the IC sealed product. Kneading a large amount of glass fibers in order to obtain the required mechanical strength is not only caused but also tends to cause the displacement of the IC element and the deformation or cutting of the bonding wire.

Further, in Japanese Patent Application Laid-Open No. Sho 59-20910, flowability, linear expansion coefficient and mechanical strength are improved by adding mica or the like to PPS having a low melt viscosity. Despite the occurrence of cracks immediately after removal from the mold and the small deformation of the gold wire inside the IC sealed product, cracks occur in the weld when cutting and bending the terminals of the IC sealed product, and good products can be obtained. There is no problem.

Furthermore, JP-A-57-63355 discloses a conventional PPS
Discloses a composition in which a specific mica and a fiber reinforcing material are blended. The disadvantage is that the lines break.

Accordingly, an object of the present invention is to obtain a composition for sealing an electronic component having a high weld strength of a molded article and excellent fluidity, and an electronic component coated or sealed with the composition.

The present inventors have conducted intensive studies to achieve the above object, and as a result, by mixing a specific ratio of mica and glass fiber in combination with a specific PPS resin, a resin for electronic component sealing that meets the above object. Finding that a composition is obtained,
The present invention has been reached.

<Means for Solving the Problems> That is, the present invention provides (a) a melt flow index of 1000 g /
10 minutes or more (ASTM D-1238 method, temperature 316 ° C, load 5 kgf measurement value), and the total sodium content in the resin is 800 ppm or less and the water-soluble chlorine content is 50 ppm or less.
A composition for sealing an electronic component, comprising 30 to 90% by weight of PS, (B) 3 to 35% by weight of mica, and (C) 5 to 40% by weight of glass fiber, and an electron covered or sealed with the composition. Provide parts.

The PPS used in the present invention has a structural formula Is a polymer containing 70 mol% or more, preferably 90 mol% or more of the repeating unit represented by the formula. When the above repeating unit is less than 70 mol%, heat resistance is unfavorably deteriorated.

The PPS can constitute less than 30 mol% of the repeating unit with a repeating unit having the following structural formula.

PPS is generally disclosed in JP-B-45-3368 and JP-B-52
Although it can be obtained by a production method represented by JP-A-12240, the PPS used in the present invention must further satisfy the following characteristics.

First, the total sodium content in the resin is 80%.
0 ppm or less, water-soluble chlorine content is 50 ppm or less, preferably total sodium content is 500 ppm or less, water-soluble chlorine content is 40 pp
m or less. 8 total sodium content
When the content exceeds 00 ppm, and when the content of water-soluble chlorine exceeds 50 ppm, the entanglement between the glass fiber and mica becomes poor, and the effect of improving the weld strength becomes insufficient.

Second, the melt flow index of PPS (ASTM D-1
238, a temperature of 316 ° C., and a load of 5 kgf) must be 1000 g / 10 min or more, preferably 5000 g / 10 min or more. If the melt flow value is less than 1000 g / 10 minutes, the melt viscosity of the composition becomes high, the fluidity during molding deteriorates, and electronic components are damaged, which is not preferable.

Based on the specific PPS having all the characteristics strictly defined in this way and by combining the specific types and proportions of fillers described later, a useful electronic component sealing composition suitable for the purpose is obtained. It is done.

The proportion of PPS in the total composition of the present invention is suitably from 30 to 90% by weight, preferably from 35 to 70% by weight. 30% by weight
If it is less than 90%, the fluidity at the time of sealing molding is reduced. If it exceeds 90% by weight, the content of the filler is too small, and the strength of the sealing molded product is undesirably reduced.

The method for reducing the total sodium content and water-soluble chlorine content of the PPS used in the present invention is not particularly limited. For example, a method of washing with hot water described in JP-A-62-153344, for example, A method of washing with a polar solvent described in JP-A-62-81160,
However, the method of treating with an aqueous acid solution and the method of combining them with the method disclosed in Japanese Patent Application Laid-Open Publication No. H10-260, can be exemplified, but the method is not limited thereto.

Mica used in the present invention is not particularly limited,
Flaked muscovites (muscovite) and phlogopite (phlogopite) are preferred. The particle size of the mica powder is preferably as fine as possible and has a large aspect ratio. Mica having large particles is not preferable because the displacement of the IC element and the deformation or cutting of the gold wire during sealing molding are not preferable.

The amount of mica is selected from the range of 3 to 35% by weight, preferably 5 to 30% by weight. Here, the compounding amount is 3% by weight.
If it is less than 35%, the effect of improving the weld strength is small, and if it exceeds 35% by weight, the melt viscosity of the composition becomes high, and the IC element,
It is not preferable because it causes damage to gold wires and the like.

The glass fiber used in the present invention is not particularly limited, but is preferably a chopped strand having a diameter of 5 to 20 μm and a length of 0.5 to 10 mm when compounded.

The content of glass fiber is 5 to 40% by weight, preferably 10 to
It is selected from the range of 35% by weight. Here, if the blending amount is less than 10% by weight, the practical strength is insufficient, and if it exceeds 40% by weight, the melt viscosity of the composition is undesirably high.

The above-mentioned mica and glass fiber can be used as they are in PPS, but it is desirable to use a silane coupling agent or a titanate coupling agent in order to improve the interfacial adhesion with PPS.

An antioxidant, a heat stabilizer, a lubricant, a coloring agent, a UV absorber, another polymer, and the like can be added to the composition of the present invention as long as the object of the present invention is not impaired.

The method for preparing the composition of the present invention is a general method and is not particularly limited. For example, each component is mixed together at room temperature using a ribbon blade type mixer or a drum type rotary mixer, and then melt-kneaded by a single screw extruder, a multi-screw extruder, a kneader or the like, and pelletized.

The melting and kneading temperature is 280 ° C or higher in order to sufficiently melt the PPS, and from the viewpoint of preventing thermal degradation and gelation of the PPS.
340 ° C or lower is preferred.

The method of coating or sealing with the composition according to the present invention is not particularly limited, either: a method in which an electronic element is fixed in a mold and molded by injection molding or transfer molding, or a composition previously molded into a film. And a method of encapsulating the product under heat and pressure.

Further, the electronic component sealed with the composition of the present invention may be treated with a peroxide such as aqueous hydrogen peroxide after molding, or may be subjected to a heat treatment at a temperature equal to or lower than the melting point of the PPS, so that the degree of crosslinking or crystallinity is increased. Can be increased, and the mechanical properties and the like can be improved.

The use of the composition for sealing electronic components of the present invention is not particularly limited as long as it can be generally considered in the concept of electronic components. For example, capacitors, resistors, integrated circuits (I
C), a transistor, a diode, a triode, a thyristor, a coil, a varistor, a connector, a converter, a microswitch and a composite part thereof, and the like. The resin composition of the present invention is coated or sealed by the above-described method. Thus, an electronic component can be obtained.

<Example> Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. All parts and percentages shown in this example are based on weight.

Reference Example 1 (Polymerization of PPS resin) 4.67 kg of a 30% aqueous sodium hydrosulfide solution in an autoclave
(25 mol of sodium hydrosulfide), 50% sodium hydroxide 2.
00 kg (25 mol of sodium hydroxide) and N-methyl-2
-Distillate containing 8 kg of pyrrolidone (hereinafter abbreviated as NMP), gradually raising the temperature to 205 ° C. while stirring, and containing 3.8 kg of water
4.1 has been removed. 1,4-Dichlorobenzene in the residual mixture
3.75 kg (25.5 mol) and 2 kg of NMP were added, and the mixture was heated at 230 ° C. for 2 hours and further at 260 ° C. for 1 hour.

The reaction product is washed five times with ion exchanged water at 70 ° C.,
The mixture was poured into NMP20 heated to 0 ° C, stirred for about 30 minutes, passed, and then washed with ion-exchanged water at about 90 ° C.

Approximately 2 kg of this wet PPS (containing about 50% water) is immersed in a hydrochloric acid aqueous solution of pH 2 kept at room temperature for 30 minutes, passed, and then ionized at room temperature until the pH of the solution becomes 7. Washed with replacement water. Next, the wet PPS and ion-exchanged water were charged into an autoclave, sealed at normal pressure, heated to 180 ° C. with stirring, kept warm for about 2 hours, and cooled. The contents were taken out of the autoclave, washed with ion-exchanged water at room temperature until the pH of the solution reached 7, and dried under reduced pressure at 120 ° C for 24 hours to obtain a powder.

The melt flow index measured for the obtained PPS (ASTM D-1238, measured at a temperature of 316 ° C under a load of 5 kgf)
Was 8000 g / 10 minutes. The total sodium content and water-soluble chlorine content of the obtained PPS were 95 ppm and 15 p, respectively.
pm.

Examples 1 to 4 PPS powder obtained in Reference Example 1 and mica (Yamaguchi Yamaguchi Co., Ltd.)
) And a glass fiber chopped strand having a diameter of 13 µm and a length of 3 mm were blended in the proportions shown in Table 1 and charged into a twin-screw extruder having a screw diameter of 30 mmφ.
Melting and kneading at ~ 310 ° C, screw speed 80 rpm, PPS
A resin composition pellet was obtained.

This pellet is supplied to the injection molding machine dedicated to inserts,
At a cylinder temperature of 320 ° C. and a mold temperature of 180 ° C., encapsulation of the semiconductor element was performed. As the semiconductor element, a semiconductor chip was used in which a semiconductor chip was mounted on ten supporting frames, and an electrode of the semiconductor chip was connected to a terminal of the supporting frame by a gold wire having a diameter of 30 μm. The displacement or damage of the gold wire of the sealed molded product was evaluated by a soft X-ray method, and the displacement was evaluated by the average value of the maximum displacement (mm) with respect to the normal gold wire position for 10 sealed components.

In addition, the strength of the welded portion of the sealing molded product was determined by visually observing the presence or absence of cracks after cutting and bending the terminal using a tie bar cutter (manufactured by Yamada Seisakusho Co., Ltd.). The results were as shown in Table 1.

As is clear from Table 1, according to the resin composition of the present invention, the displacement of the gold wire in the sealing molded product is extremely small,
In addition, it has been found that the material has excellent weld strength and is a material for electronic components with extremely high practical value.

Comparative Examples 1-2 As in Example 1, pellets were prepared by melt-kneading with the composition shown in Table 1, and then sealing molding of the semiconductor element was performed.

The results are as shown in Table 1. In Comparative Example 1 using glass fiber alone, the displacement of the gold wire was large and the wire was partially broken.

In Comparative Example 2 using mica alone, although the displacement of the gold wire was small, cracks occurred in the weld portion after the terminal was cut with a tie bar cutter.

Comparative Example 3 PPS powder “Ryton” V-1 (melt flow index: 7000 g / 10
Min, total sodium content 2000ppm, water-soluble chlorine content 60p
pm), except that pm) was used.
It is shown in the table.

<Effect of the Invention> According to the resin composition for sealing electronic components of the present invention, a gold wire,
It is possible to provide sealed molded products such as ICs and capacitors in which the damage of the internal elements is extremely small and the molded product has excellent weld strength, and is expected to have extremely practical value as a material for sealing electronic components.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C09D 181/00 C08L, C08G

Claims (2)

(57) [Claims] (1) The melt flow index is 1000 g / 10 min or more (ASTM D-1238 method, temperature 316 ° C., load 5 kgf measurement value), and the total sodium content in the resin is 800 p.
pm or less, polyphenylene sulfide resin having a water-soluble chlorine content of 50 ppm or less, 30 to 90% by weight, (b) mica 3 to
An electronic component sealing composition comprising 35% by weight and (C) 5 to 40% by weight of glass fiber. 2. An electronic component coated or sealed with the composition for sealing an electronic component according to claim 1.