JP2780271B2 - Electronic component sealing composition and resin-sealed electronic component - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a composition for sealing an electronic component containing a polyphenylene sulfide resin as an essential component, and a resin-sealed electronic component covered or sealed with a polyphenylene sulfide resin. More specifically, a composition for encapsulating an electronic component containing a polyphenylene sulfide resin having a reduced content of a water-soluble electrolyte as an essential component and a nitrogen-containing polar organic solvent by a treatment that requires washing with a nitrogen-containing polar organic solvent and an acid treatment. The present invention relates to a resin-sealed electronic component covered or sealed with a polyphenylene sulfide resin in which the content of a water-soluble electrolyte component is reduced by a process that essentially requires solvent washing and acid treatment.

<Prior art> As a resin for electronic component sealing, a thermoplastic resin having characteristics in material yield and molding speed has been attracting attention instead of a conventional thermosetting resin, and in particular, electronic components are sealed with polyphenylene sulfide resin. This is well known in JP-A-52-14938. Furthermore, in order to reduce failures such as an increase in leakage current due to corrosion of the electrodes and wiring of electronic components due to the water-soluble electrolyte component contained in the polyphenylene sulfide resin, the content of the water-soluble electrolyte component is 100 ppm or less. An electronic component sealed using polyphenylene sulfide is disclosed in Japanese Patent Application Laid-Open No. 55-156342.

It is also known to wash high-viscosity PPS for general molding with an organic solvent in order to remove oligomers in the polyphenylene sulfide resin. (For example, JP-A-62-148567 and JP-A-62-151462).

<Problems to be Solved by the Invention> In the resin-sealed electronic component disclosed in the above-mentioned JP-A-55-156342, as a method for reducing the content of a water-soluble electrolyte component in a polyphenylene sulfide resin used, Although washing with hot water of 120 ° C. or lower has been proposed, this method has a drawback that it takes a long time to reduce the amount of the water-soluble electrolyte component.

Therefore, an object of the present invention is to efficiently reduce the content of a water-soluble electrolyte component in polyphenylene sulfide in a short time.

<Means for Solving the Problems> The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have known low-viscosity polyphenylene sulfide suitable for sealing and conventionally known for de-oligomerization of high-viscosity polyphenylene sulfide. Washing with a nitrogen-containing polar organic solvent and an acid treatment resulted in a very short time reduction of the content of water-soluble electrolyte components specifically, especially the content of sodium ion and chloride ion, which is a problem in this application. The present invention has been found that the effect is further reduced when combined with an acid treatment, and the effect is further enhanced.

That is, the present invention provides (1) a composition for sealing electronic components, which comprises, as an essential component, a polyphenylene sulfide resin which has been washed with a nitrogen-containing polar organic solvent and subjected to an acid treatment;
In the above (1), the composition for sealing electronic parts, wherein the polyphenylene sulfide resin is a polyphenylene sulfide resin having a melt viscosity of 290 poise or less (300 ° C., shear rate 500 sec- ¹ ), and (3) washing with a nitrogen-containing polar organic solvent It is a resin-sealed electronic component covered or sealed with an acid-treated polyphenylene sulfide resin.

The polyphenylene sulfide used in the present invention (hereinafter referred to as PP
S) is a structural formula At least 70 mol%, more preferably
A polymer containing at least 90 mol%, wherein the repeating unit is 70
If it is less than mol%, heat resistance is impaired, which is not preferable.

PPS is generally a polymer having a relatively small molecular weight selected by the production method represented by JP-B-45-3368 and an essentially linear polymer obtained by the production method represented by JP-B-52-12240. In the polymer obtained by the method described in JP-B-45-3368, by heating in an oxygen atmosphere after polymerization, or by crosslinking of peroxide. It is also possible to increase the degree of polymerization by adding an agent and heating it. In the present invention, it is possible to use PPS obtained by any method.

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

The melt viscosity of the PPS used in the present invention needs to be low in order to form the electronic element without damaging it. Normally, 290 poise or less (300 ° C, shear rate 500 sec- ¹ )
PPS is used. In particular, when sealing a device having a bonding wire such as a transistor or an IC, a device having a low melt viscosity is preferably used in order to avoid breakage of the device.

Further, in the PPS used in the present invention, a range that does not impair the effects of the present invention, an antioxidant, a heat stabilizer, a lubricant, a crystal nucleating agent,
Usual additives such as an ultraviolet ray inhibitor, a copper damage inhibitor, a coloring agent, and a release agent can be added, and further, for the purpose of controlling the degree of crosslinking of PPS, a crosslinking accelerator such as a peroxide agent, or JP 58
It is also possible to add a crosslinking accelerator such as dialkyltin dicarboxylate and aminotriazole described in JP-A-204045 and JP-A-58-204046.

In the present invention, it is essential to wash and acidify PPS with a nitrogen-containing polar organic solvent, and when both are combined, the order of washing with an organic solvent and acid treatment is not particularly limited.

Nitrogen-containing polar organic solvent used for cleaning PPS in the present invention, PPS
There is no particular limitation as long as it does not have the action of decomposing N-methylpyrrolidone, dimethylformamide, dimethylacetamide, 1,3-dimethylimidazolidinone, hexamethylphosphorasamide, nitrogen-containing polarities such as piperazinones Solvents. Among these nitrogen-containing polar organic solvents, use of N-methylpyrrolidone, dimethylformamide and the like is particularly preferable. These organic solvents are used alone or in combination of two or more.

As a method of washing with an organic solvent, PP in an organic solvent is used.
There are methods such as immersion of S, and if necessary, stirring or heating can also be performed.

The timing of washing with an organic solvent is not particularly limited as long as it is after the polymerization of PPS, and after polymerization, it is possible to subject the post-treated / dried PPS to organic solvent washing, and use a polymerization solvent after polymerization. The PPS in a wet state can be washed with an organic solvent as it is, and furthermore, the reaction mixture after the completion of the PPS polymerization can be poured into the washing organic solvent or washed by adding the washing organic solvent into the reaction mixture. It is possible.

The washing temperature when washing PPS with an organic solvent is not particularly limited, and an arbitrary temperature from ordinary temperature to about 300 ° C. can be selected. Although the cleaning efficiency tends to increase as the cleaning temperature increases, a sufficient effect is usually obtained at a cleaning temperature of room temperature to 150 ° C.

It is also possible to wash under pressure at a temperature equal to or higher than the boiling point of the organic solvent in a pressure vessel. There is no particular limitation on the cleaning time. Although depending on the washing conditions, in the case of batch washing, a sufficient effect is usually obtained by washing for 5 minutes or more. It is also possible to wash in a continuous manner.

It is sufficient only to wash the PPS produced by the polymerization with an organic solvent, but it is preferable to combine the PPS with water washing or warm water washing in order to further exert the effects of the present invention.
When a high-boiling water-soluble organic solvent such as N-methylpyrrolidone is used, it is preferable to wash the organic solvent and then wash it with water or warm water because the remaining organic solvent can be easily removed. The water used for these washings is preferably distilled water or deionized water.

The acid used for the acid treatment of PPS in the present invention is not particularly limited as long as it does not have an action of decomposing PPS, and examples thereof include hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid, silicic acid, carbonic acid, and propyl acid. Hydrochloric acid and acetic acid can be more preferably used, but those which decompose and degrade PPS such as nitric acid are not preferred. Examples of the acid treatment method include a method of immersing PPS in an acid or an aqueous solution of an acid, and it is also possible to appropriately stir or heat if necessary.
A sufficient effect can be obtained by immersing in the aqueous solution of No. 2 for about 30 minutes. Further, after the acid treatment, it is preferable to wash several times with water or warm water in order to physically remove the remaining acids and salts.

Although the effects of the present invention are sufficiently exhibited by washing the PPS with an organic solvent and treating with an acid, it is preferable to combine PPS with hot water washing to obtain better effects.

In hot water washing, the higher the temperature of hot water, the higher the efficiency of physical removal of the water-soluble electrolyte component present in the form of acids, salts, etc. in PPS, and furthermore, such as polymer termination having a hydrolyzable electrolyte component The efficiency of chemical denaturation is also excellent and preferred. The temperature of the hot water is preferably selected to be 100 ° C. or higher, more preferably 150 ° C. or higher, and further preferably 170 ° C. or higher.

The water used for washing is preferably distilled water or one having a low content of water-soluble electrolyte components such as deionized water,
Electric conductivity of water is 1 μs / cm or less, more preferably 0.5 μs
/ cm or less is used.

The washing operation is usually performed by adding a predetermined amount of PPS to a predetermined amount of water, heating and stirring in a pressure vessel.
The ratio of PPS to water is preferably as high as possible, but a bath ratio of 200 g or less of PPS to 1 water is usually selected. The cleaning atmosphere does not need to be an inert atmosphere, and it is desirable to perform the cleaning in an oxygen atmosphere for a preferable chemical modification below PPS.

Further, the PPS after the washing operation is preferably washed several times with warm water in order to physically remove remaining salts and the like.

The PPS to be subjected to the acid treatment in the present invention is preferably in the form of a powder, and particularly preferably a fine powder in terms of the efficiency of the acid treatment. Usually, PPS produced by a known method is obtained in the form of powder and granules, and therefore, it is preferable to perform acid treatment using these without pelletizing, and particularly to make the content of the water-soluble electrolyte component extremely small. If required, it can be classified or crushed before use.

Furthermore, in the present invention, for the purpose of improving the dimensional stability, mechanical properties, heat conduction properties, etc. of electronic components sealed with PPS that has been washed with an organic solvent and subjected to acid treatment as an essential component, fused silica and crystals are used. It is preferable to mix inorganic fillers such as silica, calcium silicate, calcium sulfate, mica, talc, glass fiber and glass beads, and it is also desirable that the content of the water-soluble electrolyte component in these fillers is small. Two or more of these fillers can be used in combination, and if necessary, can be used after being pretreated with a silane-based and titanium-based coupling agent.
Moreover, it can presuppose with these coupling agents and can provide. Further, these coupling agents can be directly mixed with PPS for the purpose of improving the adhesion between the sealing resin and the electronic element.

The means for preparing the composition of the present invention is not particularly limited.
A typical method is to melt-knead the mixture with an inorganic filler at a temperature not lower than the melting point of PPS in an extruder and then pelletize.

The electronic component of the present invention is not particularly limited as long as it can be generally considered in the concept of an electronic component. For example, a capacitor, a resistor, an integrated circuit (IC), a transistor, a diode, a triode, a thyristor, a coil, and a varistor , Connectors, transducers, microswitches, and the like, and composite parts thereof.

There is no particular limitation on the method of coating or sealing with PPS in the present invention, and a method in which an electronic element is fixed in a mold and molded by injection molding or transfer molding, or a PPS previously molded into a film is used. And a method of sealing under heat and pressure.

Further, the resin-encapsulated electronic component of the present invention may be treated with a peroxide such as hydrogen peroxide solution after molding, or heat-treated at a temperature equal to or lower than the melting point of PPS to increase the degree of crosslinking or crystallinity. It is possible to improve mechanical characteristics and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples.

<Example> Reference Example 1 (Polymerization of PPS) 4.67 kg of 30% aqueous sodium hydrosulfide solution in an autoclave
(25 mol of sodium hydrosulfide), 30% sodium hydroxide 2.
00 kg (25 mol of sodium hydroxide) and N-methyl-2
-Charge 8 kg of pyridone (hereinafter abbreviated as NMP), gradually raise the temperature to 205 ° C. while stirring, and distillate containing 3.8 kg of water 4.
One was removed. 1,4-Dichlorobenzene 3.
75 kg (25.5 mol) and 2 kg of NMP were added and the mixture was added at 230 ° C for 2 hours.
Further heating was performed at 260 ° C. for 1 hour.

The reaction product was washed twice with water and five times with 70 ° C. hot water,
It dried under reduced pressure at 80 degreeC for 24 hours, and was used for the following Examples.

In addition, the amount of the obtained powdered PPS was about 2.5 kg, and the melt viscosity was 70 poise (300 ° C. shear rate was 500 sec- ¹ .
20 g of dried powder and 100 cc of ion-exchanged water were sealed in a pressure-resistant container, and the sodium and chlorine contents measured for the extract kept at 160 ° C. for 20 hours were 724 ppm and 755 ppm, respectively, based on the weight of PPS. Liquid conductivity is 52
It was 3 μs / cm.

Example 1 About 2 kg of the powder obtained in Reference Example 1 was heated to 100 ° C. NMP2
0 liter, stirred for about 30 minutes, filtered,
Subsequently, the substrate was washed with ion-exchanged water at about 90 ° C.

Next, the wet PPS obtained above was immersed in hydrochloric acid of pH 2 kept at room temperature for 30 minutes, filtered, and further washed with ion-exchanged water at room temperature until the pH of the filtrate reached 7. This wet PPS and ion-exchanged water were charged into an autoclave, sealed at normal pressure, and then stirred at 180 ° C.
, And after keeping the temperature for about 2 hours, it was cooled. The contents were taken out of the autoclave and filtered.
After washing with ion-exchanged water at room temperature until
The mixture was dried under reduced pressure for hours to obtain a powder.

Subsequently, the powder PPS was treated with a scillar coupling agent (AY43-031 manufactured by Toray Silicone Co., Ltd.) (1% by weight based on fused silica), and only 40% of fused silica (GR-80 manufactured by Toshiba Ceramics Co., Ltd.) was used. The dry blend was carried out at a weight ratio of 60, supplied to a twin screw extruder of 30 mmφ set at 310 ° C., melt-kneaded and pelletized.

Next, the pellets are supplied to a screw in-line type injection molding machine set at 320 ° C., and the aluminum circuit shown in the schematic diagram of the electronic component in FIG. 1 is placed in a mold set at a temperature of 160 to 180 ° C. Insert the attached silicone chip,
Encapsulation molding with injection pressure of 50-100kgf / cm, 16-pin DIP
Type IC was obtained.

FIG. 1 is a schematic view of an electronic component, in which a silicon chip (18) on which an aluminum circuit (19, 20) is deposited on an island (17) is composed of external leads (1 to 16). The leads 3-6 and 11-14 are connected to the aluminum circuit by bonding wires (3a, 6a, 11a, 14a) and are in a conductive state.

Between the external leads 3-11 of the obtained PPS sealed DIP type IC (1
After applying a bias voltage of DC 20V to the sample and leaving it in pressurized steam at 121 ° C and 2 atm for 100 hours, the number of disconnections due to corrosion of the aluminum circuit was measured and the defective product ratio was determined. It was right.

Example 2 A PPS-sealed DIP-type IC was obtained in exactly the same manner as in Example 1 except that the acid treatment was performed with acetic acid at pH2 instead of using hydrochloric acid at pH2.

 The evaluation results were as described in Table 1.

Example 3 A PPS-encapsulated DIP type was manufactured in exactly the same manner as in Example 1 except that the NMP cleaning was not performed in the order of the hydrochloric acid treatment in Example 1 but the hydrochloric acid treatment was performed in the order of the NMP cleaning. I got an IC. The evaluation results were as described in Table 1.

Example 4 Instead of using NMP at 100 ° C. for washing the organic solvent in Example 1, a polymerization operation was performed in exactly the same manner as in Reference Example 1, and the obtained reaction mixture was poured into NMP20, and stirred for about 30 minutes.
PPS-encapsulated DIP type was performed in exactly the same manner as in Example 1, except that the produced PPS was isolated and washed five times with 70 ° C. hot water.
I got an IC. The evaluation results were as described in Table 1.

Examples 5 and 6 PPS powder, fused silica and glass fibers (TN-103 manufactured by JEOL Ltd.), which had been washed with an organic solvent and treated with an acid in the same manner as in Example 1, were listed in Table 1 Melt kneading and sealing molding were performed in the same manner as in Example 1 to obtain a PPS sealed DIP type IC. The evaluation results were as described in Table 1.

Comparative Example 1 PPS-encapsulated DIP was performed in exactly the same manner as in Example 1, except that the PPS was not subjected to organic solvent washing and acid treatment in Example 1, but the PPS powder obtained in Reference Example 1 was used as it was. Type IC was obtained. The evaluation results were as described in Table 1.

Comparative Example 2 A polymerization operation was performed in exactly the same manner as in Reference Example 1 to obtain a reaction mixture. The resulting PPS is isolated from the reaction mixture and
After washing 5 times with hot water at 70 ° C 5 times, wet PPS and ion-exchanged water were charged into an autoclave, sealed at normal pressure, and then heated to 180 ° C with stirring and kept warm for about 2 hours. After cooling. The contents were taken out of the autoclave, washed with ion-exchanged water at room temperature, and dried under reduced pressure at 120 ° C. for 24 hours to obtain a powder.

A PPS-sealed DIP IC was obtained in exactly the same manner as in Example 1, except that the PPS powder thus obtained was used in place of the PPS powder of Example 1. The evaluation results were as described in Table 1.

Comparative Example 3 A polymerization operation was performed in exactly the same manner as in Reference Example 1 to obtain a reaction mixture. The resulting PPS is isolated from the reaction mixture and
After washing 5 times with warm water at 70 ° C., the wet PPS was immersed in hydrochloric acid of pH 2 kept at room temperature for 30 minutes,
The solution was further dried under reduced pressure at 120 ° C. for 24 hours until the pH of the solution reached 7, to obtain a powder.

A PPS-sealed DIP IC was obtained in exactly the same manner as in Example 1, except that the PPS powder thus obtained was used in place of the PPS powder of Example 1. The evaluation results were as described in Table 1.

Comparative Example 4 PPS powder, fused silica and glass fiber obtained in the same manner as in Comparative Example 2 were mixed in the proportions shown in Table 1 in Example 1.
Perform melt-kneading and seal molding in the same manner as in
IP type IC was obtained. The evaluation results were as described in Table 1.

Comparative Example 5 PPS powder, fused silica and glass fibers obtained by the same method as in Comparative Example 3 were melt-kneaded and preventively molded in the same manner as in Example 1 at the ratios shown in Table 1 to give PPS. A sealed DIP type IC was obtained. The evaluation results were as described in Table 1.

Comparative Example 6 NMP2 obtained by heating about 2 kg of the powder obtained in Reference Example 1 to 100 ° C.
0 liter, stirred for about 30 minutes, filtered,
Subsequently, the substrate was washed with ion-exchanged water at about 90 ° C.

Next, the wet PPS and ion-exchanged water obtained above 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, filtered and washed with ion-exchanged water at room temperature until the pH of the filtrate reached 7.
The powder was dried under reduced pressure at 120 ° C. for 24 hours.

The obtained PPS was subjected to an extraction operation in exactly the same manner as in Reference Example 1, and the obtained powder was cured at 230 ° C. for 3 hours in an air atmosphere. The melt viscosity of the obtained PPS powder was 350 poise (300 ° C., shear rate 500 sec- ¹ ). Subsequently, in the same manner as in Example 1, the PPS sealed DIP type
IC was obtained, but the gold wire of the insert element was broken.

<Effects of the Invention> The polyphenylene sulfide composition for sealing electronic parts and the PPS resin-sealed electronic parts of the present invention have a very low content of water-soluble electrolyte components in the sealing resin, and have reliability represented by moisture resistance. Is extremely excellent.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a silicon chip on which an aluminum circuit is deposited, used in each embodiment of the present invention.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H05K 3/28 (56) References JP-A-62-253626 (JP, A) JP-A-62-150752 (JP, A) JP-A-63-146963 (JP, A) JP-A-61-55148 (JP, A) JP-A-58-185627 (JP, A) JP-A-62-172026 (JP, A) JP-A-62-252430 (JP, A) JP, A) JP-A-62-549 (JP, A) JP-A-1-240529 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08L 81/02 C08G 75/02 -75/10

Claims (3)

(57) [Claims] An electronic component sealing composition comprising a polyphenylene sulfide resin, which has been washed with a nitrogen-containing polar organic solvent and subjected to an acid treatment, as an essential component. 2. The melt viscosity of the polyphenylene sulfide resin
The composition for sealing electronic parts according to claim 1, wherein the composition is a polyphenylene sulfide resin having a 290 poise or less (300 ° C, shear rate 500 sec- ¹ ). 3. A resin-sealed electronic component coated or sealed with a polyphenylene sulfide resin which has been washed with a nitrogen-containing polar organic solvent and subjected to an acid treatment.