ELECTROCONDUCTIVE ADHESIVE COMPOSITION

Abstract

The present invention is to provide an electroconductive adhesive composition which contains a thermoplastic resin and has high heat dissipation properties and which is inhibited from suffering the bleeding-out phenomenon in which a nonpolar solvent undesirably bleeds out after die bonding. The present invention relates to an electroconductive adhesive composition including (A) electroconductive particles, (B) a thermoplastic resin, (C) a nonpolar solvent, and (D) a water-insoluble fluorochemical surfactant.

Claims

1. An electroconductive adhesive composition comprising: (A) electroconductive particles; (B) a thermoplastic resin; (C) a nonpolar solvent; and (D) a water-insoluble fluorochemical surfactant.

2. The electroconductive adhesive composition according to claim 1, which contains fluorine in an amount of at least 20 mass ppm of the whole electroconductive adhesive composition.

3. The electroconductive adhesive composition according to claim 1, which contains fluorine in an amount of at least 40 mass ppm of the whole electroconductive adhesive composition.

4. The electroconductive adhesive composition according to claim 1, wherein the water-insoluble fluorochemical surfactant (D) has a fluorine content of 20-70%.

5. The electroconductive adhesive composition according to claim 1, wherein the water-insoluble fluorochemical surfactant (D) is a fluorochemical surfactant having a perfluoroalkyl group.

6. The electroconductive adhesive composition according to claim 1, wherein the water-insoluble fluorochemical surfactant (D) is an ethylene oxide adduct having a perfluoroalkyl group.

7. The electroconductive adhesive composition according to claim 1, wherein the water-insoluble fluorochemical surfactant (D) is an oligomer compound having a perfluoroalkyl group.

8. The electroconductive adhesive composition according to claim 1, wherein the electroconductive particles (A) are powdery metallic particles comprising Ag or Cu as a main component.

9. The electroconductive adhesive composition according to claim 1, wherein the thermoplastic resin (B) is an ester resin.

10. The electroconductive adhesive composition according to claim 9, wherein the ester resin is a saturated ester resin.

11. The electroconductive adhesive composition according to claim 1, wherein the nonpolar solvent (C) comprises one or more aliphatic or aromatic hydrocarbons.

Description

EXAMPLES

[0073] The present invention is explained below in more detail by reference to Examples, but the present invention should not be construed as being limited by the following Examples in any way.

Examples 1 to 8 and Comparative Examples 1 to 6

A. Preparation of Adhesive Compositions

[0074] The materials shown in Table 1 were kneaded with a three-roll mill and a homogenizer to prepare adhesive compositions respectively having the makeups shown in Table 1. (The numerals for each material indicate amounts in % by mass based on the whole mass of the respective adhesive compositions.) The materials used are as follows. The sequence of kneading was: (C) nonpolar solvent, (B) ester resin, (A) electroconductive particles, and (D) fluorochemical surfactant. Each adhesive composition was heated at 200 C. for 1 hour and then allowed to cool to room temperature to obtain a cured object of the adhesive composition.

(A) Electroconductive Particles

[0075] As electroconductive particles, use was made of a silver powder obtained by mixing a flaky silver powder having an average particle diameter (D50) of 3 m manufactured by Tanaka Kikinzoku Kogyo K.K. and a flaky silver powder having an average particle diameter (D50) of 6 m manufactured by Tanaka Kikinzoku Kogyo K.K., in a ratio of 1:1.

(B) Thermoplastic Resin

[0076] As a thermoplastic resin, use was made of a powdery saturated-ester resin (glass transition point, 70-80 C.; softening point, 120-130 C.) manufactured by Tanaka Kikinzoku Kogyo K.K. With respect to the size of the resin, the average particle diameter (D50) thereof was 10 m. The thermoplastic resin used was ascertained to be undissolved in each adhesive composition and present in the powdery state.

(C) Nonpolar Solvent

[0077] As a nonpolar solvent, use was made of a solvent obtained by mixing BAB (alkylbenzenes), manufactured by FORMOSAN UNION CHEMICAL CORP., and Normal Paraffin H, manufactured by JXTG Nippon Oil & Energy Corp., in a ratio of 1:1.

(D) Water-Insoluble Fluorochemical Surfactants

[0078] Perfluoroalkyl ethylene oxide compound [Surflon 5420; AGC Sei Chemical Co., Ltd.]; fluorine content, 47%; 0.5%-concentration surface tension in ethyl acetate (mN/m), 23.1 [0079] Oligomer compound having perfluoroalkyl group [Surflon 5651; AGC Sei Chemical Co., Ltd.]; fluorine content, 23%; 0.5%-concentration surface tension (mN/m), 23.0 [0080] Oligomer compound having perfluoroalkyl group [Surflon 5611; AGC Sei Chemical Co., Ltd.]; fluorine content, 10%; 0.5%-concentration surface tension in ethyl acetate (mN/m), 18.4

[0081] The fluorine content of each of the fluorochemical surfactants was determined by ion chromatography.

(Non-Fluorochemical Surfactants)

[0082] In Comparative Examples, the following non-fluorochemical surfactants were used in place of the water-insoluble fluorochemical surfactants. [0083] Antox EDH-400, manufactured by Nippon Nyukazai Co., Ltd. (Comparative Example 2) [0084] Newcol 2609, manufactured by Nippon Nyukazai Co., Ltd. (Comparative Example 3) [0085] Newcol 565-PS, manufactured by Nippon Nyukazai Co., Ltd. (Comparative Example 4) [0086] AMIET 320, Kao Corp. (Comparative Example 5) [0087] HOMOGENOL L-95, Kao Corp. (Comparative Example 6)

B. Property Evaluation of the Adhesive Compositions

1. Bleeding-Out Property

[0088] First, 5.0 g of each sample was packed into a 5-cc Musashi syringe and applied to a copper frame or a silver-plated copper frame using a dispenser so as to form ten dots of the sample each weighing 0.15 mg.

[0089] Using microscope STMT, manufactured by Olympus Co., Ltd., the dots were examined for bleeding-out under the following conditions (1) and (2).

(1) immediately after application (after 0 hour)
(2) at two hours after application

[0090] In the examination, the dimension of the width (m) ranging from the periphery of each circle of the applied adhesive to the periphery of the bleedout was measured. With respect to each dot, the measurement was made on four portions, i.e., upper, lower, left-hand, and right-hand portions. [Evaluation]

[0091] An average value of bleedout dimension was determined for each sample for each set of conditions, and each sample was evaluated in accordance with the following criteria. Symbol indicates that the bleeding-out inhibitory effect is excellent, indicates that said effect is good, and x indicates that said effect is poor.

Silver-Plated Copper Frame

[0092] : bleedout, less than 100 m

[0093] : bleedout, 100 m or larger but less than 200 m

[0094] x: bleedout, 200 m or larger

Copper Frame

[0095] : bleedout, less than 100 m

[0096] : bleedout, 100 m or larger but less than 300 m

[0097] x: bleedout, 300 m or larger

[0098] Each of the adhesive compositions of the Examples and Comparative Examples was evaluated for a total of four items under the conditions (1) and (2), the order of evaluation priority being x>>. The results of evaluation with higher priority are shown in Table 1 as overall evaluation.

2. Evaluation of Electrical Conductivity

[0099] The adhesive compositions prepared above were each applied on a glass substrate, which had been masked with a transparent PET sheet tape manufactured by Nichiei Kakoh Co., Ltd., by stencil printing in a pattern having a width of 0.5 mm and a length of 60 mm. This glass substrate was placed in an oven and the applied adhesive composition was cured under the conditions of 200 C. and 60 minutes. Thereafter, the glass substrate was cooled to room temperature, and terminals were brought into contact with both ends of a 5-cm-long section of the cured film to measure the resistance. The thickness of the cured film was also measured. The volume resistivity was calculated from the measured resistance value and film thickness to evaluate the electrical conductivity (.Math.cm). The resistance of the cured film was measured with M-Ohm HiTESTER 3540, manufactured by Hioki E.E. Corp. The thickness of the cured film was measured with surface roughness meter Surfcorder SE-30H, manufactured by Kosaka Laboratory Ltd. The results are shown in Table 1.

TABLE-US-00001 TABLE 1 (mass %) Example Example Example Example Example Example Example Example Ingredient Kind 1 2 3 4 5 6 7 8 (A) Ag powder 41.7 41.7 41.7 41.7 41.7 41.7 41.7 41.7 Electro- (D50: 3 M) conductive Ag powder 41.7 41.7 41.7 41.7 41.7 41.7 41.7 41.7 particles (D50: 6 M) (B) Ester resin thermoplastic resin 7.2 7.2 7.2 7.2 7.2 7.2 7.2 7.2 (C) Nonpolar BAB 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 solvent Normal Paraffin H 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 (D) Water- Surflon S420 0.020 0.040 0.080 0 0. 0 0.008 0 insoluble (fluorine: 47%) fluoro Surflon S651 0 0 0 0.020 0.040 0 0 0 chemical (fluorine: 23%) surfactant Surflon S611 0 0 0 0 0 0.100 0 0.020 (fluorine: 10%) Non- EDH-400 0 0 0 0 0 0 0 0 fluoro- Newcol 2609 0 0 0 0 0 0 0 0 chemical Newcol 565-PS 0 0 0 0 0 0 0 0 surfactant AMIET 320 0 0 0 0 0 0 0 0 HOMOGENOL 0 0 0 0 0 0 0 0 L-95 Total 100 100 100 100 100 100 100 100 Fluorine content, 94 189 377 46 92 100 38 20 calculated value (ppm) Bleedout Silver-plated copper 24 16 15 44 43 39 121 150 (m) frame, 0 hr Silver-plated copper 33 23 20 61 59 43 145 168 frame, 2 hrs Copper frame, 0 hr 37 29 31 70 65 61 189 234 Copper frame, 2 hrs 51 39 33 96 91 70 231 271 Overall evaluation Electrical conductivity ( .Math. cm) 18 20 20 21 27 26 22 20 (mass %) Comparative Comparative Comparative Comparative Comparative Comparative Ingredient Kind Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 (A) Ag powder (D50: 3 M) 41.7 41.6 41.6 41.6 41.6 41.6 Electro- Ag powder (D50: 6 M) 41.7 41.6 41.6 41.6 41.6 41.6 conductive particles (B) Ester resin thermoplastic resin 7.2 7.2 7.2 7.2 7.2 7.2 (C) Nonpolar BAB 4.7 4.7 4.7 4.7 4.7 4.7 solvent Normal Paraffin H 4.7 4.7 4.7 4.7 4.7 4.7 (D) Water- Surflon S420 0 0 0 0 0 0 insoluble (fluorine: 47%) fluoro- Surflon S651 0 0 0 0 0 0 chemical (fluorine: 23%) surfactant Surflon S611 0 0 0 0 0 0 (fluorine: 10%) Non- EDH-400 0 0.299 0 0 0 0 fluoro- Newcol 2609 0 0 0.299 0 0 0 chemical Newcol 565-PS 0 0 0 0.299 0 0 surfactant AMIET 320 0 0 0 0 0.299 0 HOMOGENOL L-95 0 0 0 0 0 0.299 Total 100 100 100 100 100 100 Fluorine content, calculated value (ppm) 0 0 0 0 0 Bleedout Silver-plated copper 209 207 276 182 219 214 (m) frame, 0 hr Silver-plated copper 243 249 350 201 224 246 frame, 2 hrs Copper frame, 0 hr 329 322 426 264 315 350 Copper frame, 2 hrs 373 369 511 312 353 384 Overall evaluation X X X X X X Electrical conductivity ( .Math. cm) 19 18 23 20 21 19

[0100] As the results in the table show, the electroconductive adhesive compositions of the invention retained satisfactory electrical conductivity and were inhibited from suffering bleeding-out, due to the inclusion of a water-insoluble fluorochemical surfactant. In particular, Examples 1 to 6, which each had a fluorine content of 40 ppm or higher, were found to be remarkably inhibited from suffering bleeding-out.

[0101] While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

[0102] This application is based on a Japanese patent application filed on Mar. 31, 2017 (Application No. 2017-072959), the contents thereof being incorporated herein by reference.