WO2002034856A1

WO2002034856A1 - Hot-melt adhesive for electronic components

Info

Publication number: WO2002034856A1
Application number: PCT/KR2001/001814
Authority: WO
Inventors: Ha-Seung Jung; Il-Won An; Soon-Cheol Choi
Original assignee: Seong Il Chemical Co., Ltd.
Priority date: 2000-10-27
Filing date: 2001-10-26
Publication date: 2002-05-02
Also published as: KR20020032748A; AU2002214343A1; KR100400876B1

Abstract

A hot melt composition for electronic components comprising as main components about 10 to 40 % by weight of polyolefin wax, about 5 to 15 % by weight of butene-propylene copolymer, about 2 to 40 % by weight of dicyclopentadiene (DCPC) and about 0.1 to 5 % by weight of polybutene. The competition according to the invention has an excellent extension strengh at lower temperature as well as higher temperature, which is required for manufacturing the circuit wafers for electric or electronic components, especially for monitors, and has an improved cold resistance, stability at high temperature, and heat-resistance when compared to the conventional hot melt composition. Therefore, the composition may be useful for manufacturing the electronic components.

Description

HOT-MELT ADHESIVE FOR ELECTRONIC COMPONENTS

TECHNICAL FIELD The present invention relates to a hot melt composition for electronic components, more particularly, to a hot melt composition for adhering electronic components which is comprising about 10% to about 40% by weight of polyolepin based wax component, about 5% to about 15% by weight of polypropylene, about 10% to about 50% by weight of an butene-propylene copolymer, about 2% to about 40% by weight of dicyclopentadiene (DCPD), and about 0.1% to about 5% by weight ofpolybutene.

BACKGROUND ART

A hot melt adhesive is used as a non-solvent type adhesive which has a solid content of 100% at room temperature. The hot melt adhesive is heated and molten for use, and it is adhered and applied to various matters to be adhered, and then it is followed by cooling to solidify it, by which the adhesive strength is revealed. The hot melt adhesive has been used widely in packing, bookbinding or woodworking as well as electric home appliances. Since a hot melt adhesive is heated at high temperatures and molten, followed by cooling immediately after being applied, a continuous process is allowed. Also, since no volatile content is generated, applying thickness can be easily controlled and the applying can be achieved uniformly. Also, the hot melt adhesive has less risk of a fire. Generally, the hot melt composition comprised three main components of a base polymer, a tackifying resin and a wax. In some cases, an antioxidant, a plasticizer, a flame retardant or the like may be further added.

Ethylene Vinyl Acetate (EVA) copolymer is the prime component of the hot melt composition, and polyamide, polyester, atactic polypropylene or the like have also been used as its main components. Additionally, rosin based resins, petroleum resins or the like used as the tackifier are mixed with the main components, and waxes, antioxidants, inorganic fillers, plasticizers or the like may be further added to mix with them.

The hot melt adhesives are provided in various forms such as pellet, block and so on, and a desired form is selected regarding to its usage or direction for use. If the temperature is lowered, the hot melt adhesive quickly adheres, that is, usually within one second, thereby allowing a continuous adhesion process. Even a liquid adhesive can be suitably applied to complicated targets such as vertical planes or downwardly sloping planes. Also, since the hot melt adhesive exhibits the maximum adhesion strength immediately after being cooled, it has an advantage that it can be used to materials that cannot be adhered by ordinary adhesives such as polyethylene or polypropylene.

The conventional hot melt adhesive is generally used to packaging, bookbinding, woodworking, electric or electronic fields. The conventional hot melt adhesive, however, cannot be easily applied to the electronic components since it has several problems of heat resistance, cold resistance, adhesive strength, flame retardancy, heat impact and so on.

Particularly, in case of electric or electronic components which are recently increased the demand, it is desired that the hot melt adhesive must have some preferable characteristics for mounting the electronic components on the printed circuit board (PCB). The PCBs are manufactured by printing circuits which are applied cooper membrane onto the substrate of the sheet-epoxy type or the glass- epoxy type, and by removing remainder, and then many of integrated circuit (IC) or the like are mounted thereon. Therefore, the hot melt adhesive for applying electric or electronic components must have preferable electric characteristics. In particular, although the known hot melt compositions are mostly applied to various fields of paper or nonwoven industry and are widely used as adhesives of materials for automobile trim, they have not been satisfactory in terms of cold resistance, heat resistance. Accordingly, there has been an imperative need for development of new hot melt compositions with high-temperature heat resistance, and cold resistance, which are necessary properties for electric or electronic devices since a few technology had developed and only a few enterprises contain the technology.

As a representative example, 3M (Minnesota Mining and Manufacturing company, USA) having most of technology of hot melt compositions for electronics components, developed to sell various products of hot melt compositions. Among them, hot melt compositions for electronics components developed adhesive which is comprising about 10% to 70% by weight of amorphous polypropylene, about 2% to 70% by weight of styrene-dien block copolymer as styrene-based thermoplastic elastomer, about 1% to 35% by weight of tackifier, and about 2% or below by weight of wax components (Refer to Korean patent publication number 96-8484), Since resistance at low and high temperature or the like by adding amorphous polypropylene into EVA-based hot melt composition may be improved (Refer to Japanese patent laid-open publication number 60-120775), the hot melt compositions using amorphous polypropylene have made intensive researches and developed. In the patent of 3M, since it uses amorphous polypropylene, and it add styrene-based block copolymer rubber, characteristic of the hot melt composition are improved.

The present inventors made intensive researches and developed a new hot melt composition for adhesion of electronic components or electric components. The present inventors found that the developed hot melt composition had good cold resistance, heat resistance and resistance at low temperature as well as at high temperature, and finally completed the present invention.

SUMMARY OF THE INVENTION

It is an objective of the present invention to provide a hot melt composition with new composition, having characteristic useful to adhesion of electronic components or electric components. More particularly, It is an objective of the present invention to provide a hot melt composition which may be effectively used in a adhesion of electric components or electronic components since it has a no-erosive characteristic to copper, high shearing strength at low temperature, high creep resistance at high temperature, and resistance at a low temperature such as -40°C.

To accomplish the above objectives, the present invention provides a hot melt composition comprising of about 10% to about 40% by weight of polyolepin based wax component; about 5% to about 15% by weight of polypropylene; about 10% to about 50% by weight of an butene-propylene copolymer; about 2% to about 40% by weight of dicyclopentadiene (DCPD) resin; and about 0.1% to about 5% by weight of polybutene.

It is preferred that the polyolefin based wax component is polyethylene or polypropylene wax. By using polyolefin based wax, heat resistance and melting viscosity are improved. If the wax component used is less than, it is difficult to control the melting viscosity, the workability is inferior, and a hanging loop phenomenon occurs. If the wax component used is greater than, the adhesive strength is reduced and the poor low temperature adhesion characteristic is resulted. It is more preferred that the polypropylene wax is about 5% to about 20% by weight, and the polyethylene wax is about 5% to about 20% by weight.

It is preferred that the polypropylene wax has a molecular weight of about 1,000 to about 5,000, and the polyethylene wax has a molecular weight of about 1,000 to about 3,000. By using polyolefin based wax, a set time of compositions of the adhesive is improved, and by improving a characteristic of dealing the compositions by means of changing viscosity, the workability may be improved.

Polypropylene and butane-propylene copolymer as the base polymer which are included in the adhesive are added to allow a flexibility of the adhesive and to improve an adhesion strength, and it is preferred that the butane-propylene copolymer has a molecular weight of 1,000 to 50,000. If contents of the polypropylene and butane-propylene copolymer as the base polymer is greater than, the resultant composition becomes too soften so as to deteriorate its strength, and if less than, the resultant composition may be easily broken. It is preferred that the polypropylene is an atactic polypropylene, but a little of isotactic polypropylene or syndiotactic polypropylene may be included. In a preferred embodiment according to the present invention, except for not including butane-propylene copolymer and polybutene, physical characteristics of the composition according to the present invention was compared with them of Comparative Example which is a hot melt composition similar to the composition according to the present invention. As a result of comparison, since viscosity are too low, it was anticipated a problem for the set time. Although a cold resistance of the present invention is up to -40°C, the Comparative Example has about -27°C of a cold resistance. Also, it is resulted that tensile strength of the Comparative Example at low and high temperature has 1/2 times of strength compared to the present invention. Therefore, in order to have a preferable cold resistance, the workability, and the resistance at low and high temperature according to the present invention, it is required that an amount of butane-propylene copolymer is to add properly.

In the hot melt composition according to the present invention, polybutene as another component of the hot melt invention, it improves overall characteristics of the hot melt compositions, and allows to provide tackifying, and provides essential insulating characteristic for being used in adhesive of electronic components or electric components.

In order to increasing compatibility of the components, DCPD resin is preferable used. It is preferred that the DCPD resin has a molecular weight of 1 ,000 to 50,000, which improves compatibility and adhesion.

Except the above-mentioned components, additional ingredients such as a filler, a plasticizer, an anti-oxidant, a flame retardant and a colorant may be used in the hot melt component regarding to its characteristic and usage according to the present invention. For example, usable fillers include calcium carbonate and talcum, the plasticizer includes paraffin or naphtene based hydrocarbon oil, and the flame retardant include halogens, phosphates and the like. These additional ingredients are generally inert and do not affect the properties of substantially main components such as base polymer, wax, and tackifier.

A process of preparing a hot melt composition is achieved by being molten and blending the above-mentioned components and preferable additional ingredients by means of the common process. In order to acquire more uniform compositions, in the agitation tank maintained at about 150°C to about 250°C, the wax components, polypropylene, base polymer, DCPD resin, and polybutene are sequentially provided to be molten enough, and then may be provided additional ingredients such as a filler, a plasticizer, an anti-oxidant, a flame retardant and a colorant. And then, after completely melting the components with stirring, the resultant was cooled using a conveyer belt and manufactured as a chip-form hot melt composition.

In an embodiment according to the present invention, hot melt compositions with various compositions within a range of above-mentioned compositions and compositions as Comparative Example, without including butane-propylene copolymer and polybutene are manufactured, and then characteristics such as viscosity, tensile strength at low and high temperature, and cold resistance are observed. Firstly, the hot melt compositions prepared were molten at about 180°C to about 220°C, applied to make test specimens and cooled to room temperature. The prepared specimens were placed in constant temperature chambers maintained at temperatures of -40°C, allowed to taken out after 100 hours, and were observed by the naked eye whether occurrence of cracking or fiaking-off of the connected parts of the specimens or not. As a result, hot melt composition in Comparative Examples without comprising butane-propylene copolymer and polybutene had cold resistance up to -27°C and exhibited cracking and flaking-off. However, hot melt composition in Examples 1 to 7 according to the present invention did not occur cracking or flaking-off even at -40°C. On the other hand, test specimens were heated at a dry oven maintained at about 80°C or about 25°C for about one hour. After one hour, the specimens were taken out and then pulled within 10 seconds by a push pull gauge at a tensile rate of 10 m /min to measure the maximum load until the test specimens were broken. The hot melt composition according to the present invention exhibited a tensile adhesive strength of about 17 to about 20 kgf/cm² at 80 °C, compared to known hot melt compositions in Comparative Example exhibiting a tensile adhesive strength of about 9.3 kgf/cm². Also, about 28 to about 33 kgf/cm² of a tensile adhesive strength at 25 °C was about 2 times better than, compared to known hot melt compositions in Comparative Example exhibiting a tensile adhesive strength of about 13.5 kgf/cm . Therefore, it was confirmed that the hot melt composition according to the present invention has an excellent characteristics in view of tensile adhesive strength at low temperature as well as at high temperature. Also, hot melt compositions are molten at about 180°C, and are calculated of 5350 -5850 cpa/180°C of viscosity at a 180°C, which are acceptable in the work.

The hot melt compositions according to the present invention may be preferable used to adhere device to a printed circuit board for electronic components, especially for monitors.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described in detail through preferred embodiments. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein.

Example 1 : (1) Preparation of hot melt composition

11 kg of polypropylene wax, 20 kg of polyethylene wax, and 5 kg of polypropylene were injected into a 500 / heat-melting agitation tank at a rate of 80 rpm (rate per minute) at about 200°C. The wax components were molten in the agitation tank maintained at about 150°C to about 250°C, and were followed by adding 45 kg of butene-propylene copolymer with a molecular weight of 1,000 to 50,000 as a base polymer. After completely melting the components with stirring for about 2 hours, about 19 kg of DCPD resin and about 0.1 kg of polybutene were further added to be molten. After heating all the component materials to be molten, the resultant was cooled using a conveyer belt and manufactured as a chip-form hot melt composition.

Example 2~7 : (2) ~(7) Preparation of hot melt composition A hot melt chip was prepared in the same manner as in the above-mentioned Example 1 using different kinds of wax, base polymer, tackifying resin and polybutene. The components and contents of the respective compositions are listed in Table 1.

Experimental example 1 : Cold resistance test

The hot melt compositions prepared in Examples were molten at about 180°C to about 220°C, applied to make test specimens which are connected PCB and Aluminum electrolytic condenser and cooled to room temperature. The prepared specimens were placed in constant temperature chambers maintained at temperatures of -40°C, allowed to taken out after 100 hours, and were observed by the naked eye whether occurrence of cracking or flaking-off of the connected parts of the specimens or not. As a comparative example, hot melt composition composed of component materials listed in Table 2 are used.

Table 2. Cold resistance test

As a result, hot melt composition in Comparative Examples which did not compose of butane-propylene copolymer and polybutene had cold resistance up to - 20°C and exhibited cracking and flaking-off at -30°C or below. However, hot melt composition in Examples 1 to 7according to the present invention did not occur cracking or flaking-off even at ~40°C. Therefore, it was confirmed that the hot melt composition according to the present invention had so good cold resistance as to withstand at -40°C at a minimum. The results are listed in Table 3.

Table 3. Cold resistance test

Experimental example 2: Viscosity test

Hot melt composition in the Example 1 to 7 and in the Comparative Example 1 to 2 are molten at about 180°C to 220°C, and are calculated a viscosity at a 180°C (cps/180°C) by using viscometer, for example, Tokyo Keoki BL Type viscometer made in Japan. The results are shown in Table 4.

Table 4. Viscosity test

Experimental example 3: Tensile adhesive strength test

The hot melt composition in Example 1 to 7 according to the present invention was molten at about 180°C to about 220°C, applied to an adhesion surface of a prepared target to be coated within 5 seconds and allowed to stand at room temperature for about 1 hour. The target was prepared by placing two specimens made of steel and each having a length of 100±0.5 mm and a width of 25±0.5 mm, such that one specimen lays over the other by 12.55±0.5 mm, and coating the hot melt adhesive therebetween. Thereafter, test specimens were heated at a dry oven maintained at about 80°C or about 25°C for about one hour. After one hour, the specimens were taken out and then pulled within 10 seconds by a push pull gauge at a tensile rate of 10 mm/min to measure the maximum load until the test specimens were broken. The measurement results are shown in Table 5.

Table 5. Tensile adhesive strength test

As shown in Table 5, the hot melt composition according to the present invention exhibited a tensile adhesive strength of about 17 to about 20 kgf/cm² at 80 °C, compared to known hot melt compositions in Comparative Example exhibiting a tensile adhesive strength of about 9.3 kgf/cm . Also, about 28 to about 33 kgf/cm of a tensile adhesive strength at 25 °C was about 2 times better than, compared to known hot melt compositions in Comparative Example exhibiting a tensile adhesive strength of about 13.5 kgf/cm². Therefore, it was confirmed that the hot melt composition according to the present invention has an excellent characteristics in view of tensile adhesive strength at low temperature as well as at high temperature.

INDUSTRIAL APPLICABILITY

The hot melt composition according to the present invention has excellent adhesive strength, its cold resistance, heat resistance and heat impact strength. Accordingly, the hot melt composition according to the present invention may be effectively used in the electric/electronic field such as a connection electric/electronic components, for example, a connection some devices to printed circuit board, which are required cold resistance, heat resistance and resistance at a low temperature and at a high temperature or the like.

Claims

WHAT IS CLAIMED IS:

1. A hot melt composition for electric or electronic components, the hot melt composition comprising: about 10% to about 40% by weight of polyolepin based wax component; about 5% to about 15% by weight of polypropylene; about 10% to about 50% by weight of an butene-propylene copolymer; about 2% to about 40% by weight of dicyclopentadiene (DCPD) resin; and about 0.1% to about 5% by weight of polybutene.

2. The hot melt composition according to claim 1, wherein the polyolefin based wax component is polyethylene or polypropylene wax.

3. The hot melt composition according to claim 2, wherein the polypropylene wax is about 5% to about 20% by weight, and the polyethylene wax is about 5% to about 20% by weight.

4. The hot melt composition according to claim 3, wherein the polypropylene wax has a molecular weight of about 1,000 to about 5,000, and the polyethylene wax has a molecular weight of about 1 ,000 to about 3,000.

5. The hot melt composition according to claim 1, wherein the butene- propylene copolymer has a molecular weight of 1,000 to 50,000.

6. The hot melt composition according to claim 1, wherein the DCPD resin has a molecular weight of 1,000 to 50,000.

7. The hot melt composition according to claim 1, further comprising at least one component selected from the group consisting of a filler, a plasticizer, an anti-oxidant, a flame retardant and a colorant.