• Proceedings of the KWS Conference
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• 2009.11a
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• pp.74-74
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• 2009

카본나노튜브(CNT) 복합체는 우수한 기계적 성질을 가지고 있어 다양한 분야에서 연구되고 있다. 본 연구에서는 카본나노튜브(CNT)를 간단한 볼밀공정을 사용하여 Sn3.5Ag solder ball과 SAC305 powder 표면에 혼합하고 이를 통해 접합부 특성을 관찰하였다. 볼밀을 실시하기 전 카본나노튜브(CNT)는 초음파을 이용하여 분산을 실시하였다. Sn3.5Ag solder ball의 직경은 450um이고 SAC305 powder의 직경은 약 30um이었으며 이때 사용한 볼밀볼의 직경은 각각 3mm, 1mm이다. 볼밀 회전속도는 약 300rpm이고 6, 12, 18, 24시간동안 볼밀을 실시하였다. 24시간 볼밀 후에도 solder ball과 solder powder의 모양은 크게 변하지 않았다. SEM을 통해 표면을 관찰한 결과 분산된 카본나노튜브(CNT)는 solder ball과 solder powder의 표면에서 관찰되었다. 카본나노튜브(CNT)가 삽입된 solder ball은 BGA coupon 위에 놓고 Reflow를 실시하여 접합하였고 solder powder은 flux를 첨가하여 paste로 제조하여 2012 chip에 대한 접합특성을 관찰하였다. 카본나노튜브(CNT)는 solder ball 내부의 표면근처에서 관찰되었으며 카본나노튜브(CNT)가 혼합된 solder ball은 Aging 실시 후에 IMC 두께가 카본나노튜브(CNT)가 혼합되지 않은 solder ball에 비해 두께가 작고 접합강도는 약 10% 증가하였다. 또한 카본나노튜브(CNT)가 혼합된 solder paste와 카본나노튜브(CNT)가 혼합되지 않은 solder paste를 비교한 결과 인쇄성은 모두 양호하였으며 카본나노튜브(CNT)가 혼합된 paste를 사용한 chip의 전단강도가 높게 나타났다.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.2
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• pp.33-42
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• 2023

Throughout all industries, eco-friendliness is being promoted worldwide with focus on suppressing the environmental impact. With recent international environment policies and regulations supported by government, the electric vehicles demand is expected to increase rapidly. Battery system itself perform an essential role in EVs technology that is arranged in cells, modules, and packs, and each of them are connected mechanically and electrically. A multifaceted approach is necessary for battery pack bonding technologies. In this paper, pros and cons of applicable bonding technologies, such as resistance welding, laser and ultrasonic bonding used in constructing electric vehicle battery packs were compared. Each bonding technique has different advantages and limitations. Therefore, several criteria must be considered when determining which bonding technology is suitable for a battery cell. In particular, the shape and production scale of battery cells are seen as important factors in selecting a bonding method. While dealing with the types and components of battery cells, package bonding technologies and general issues, we will review suitable bonding technologies and suggest future directions.

• Journal of Welding and Joining
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• v.14 no.6
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• pp.37-47
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• 1996

An ultrasonic testing uses the directivity of the ultrasonic wave which propagates in one direction. The directivity is expressed as the relationship between the propagate direction and its sound pressure. The directivity of ultrasonic wave is related to determination of testing sensitivity, scanning pitch and defect location. This paper investigated the directivity of ultrasonic wave, which scattered from slit defect located in heat-affected zone (HAZ) in butt joint using visualization method. The directivity of shear waves scattered from slit defect were different according to probe direction (far defect, near defect) and probe position (forward movement, maximum echo position, backward movement). The difference of directivity of reflection wave was existed between 2 MHz and 4 MHz angle probes. In the case of 2 MHz angle probe, the directivity of reflection wave was appeared sharp form because of the relation wave length and defect size.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.4
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• pp.41-47
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• 2000

In this study, the purpose finds out the best welding conditions for bonding of electric wire by ultrasonic welding. The material was plastic-insulating low-voltage-cabels for automobiles. The experiment varied the values of welding time and welding pressure and fixed the values of amplitude and energy. With the facts, the best condition for ultrasonic welding to achieve bonding exactly is gained according to the size of the cross-sectional area of the cable, and the adhesive intensity is greatly influenced by the variables of welding time and welding pressure. Also when the welding time and welding time and welding pressure increase as the cross-sectional areas of the cable increase the welding result in gained exactly.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.726-730
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• 1997

One approach to testing the suitability of an adhesive joint for a particular application is to build and test to destruction a representativc, sample of the joini. The noncdestructive test will not measure strength directly but will measure a parameter which can be correlated to strength. It is thercforc, essential that a suitable nondestructive rest is chosen and that its results are correctly intcrpreted. In this paper, typical Ultrasonic Signal Analysis in adhesive joints are cvaluatcci together with Interface Stress from the result of Finite Elenlent Method.

• Journal of Welding and Joining
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• v.15 no.3
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• pp.109-117
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• 1997

The temperature gradient in weldment changes the transit time and distorts the direction of the ultrasound beam to the higher temperature regions due to the lower sound speed in the hotter regions of the weldment. This paper describes a ray-tracing method for calculating the effects of temperature gradients on ultrasonic propagation in fillet arc weldig. In the method, weldment is conceptually devided into a number of layers and the refraction and sound speed at each layer is calculated using the temperature which calculated from analytical solution. Calculating the time and location of echoes arrived from various interfaces around a molten weld pool determines the optimum location of ultrasonic transducers and the correct position of flaws.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.534-540
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• 2001

One approach to testing the suitability of an adhesive joint for a particular application is to build and test to destruct ion a representative sample of the joint. The nondestructive test will not measure strength directly but will measure a parameter which can be correlated to strength. It is therefore, essential that a suitable nondestructive test is chosen and that its results are correctly interpreted. In this paper, typical defects found in adhesive joints are described together with their significance. The limits and likely success of current physical nondestructive tests are described, and future trends outlined.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1109-1114
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• 2003

The initial crack often occurs on the bonded interface and it is the general cause of the interface fracture. It is very significant to establish the measurement method of interfacial crack by applying the ultrasonic technology into the interface of bonded dissimilar materials. In this paper, the interfacial crack length was measured by ultrasonic attenuation coefficient in the Al/Epoxy bonded dissimilar materials of double-cantilever beam(DCB). The energy release rate, G, was obtained by the experimental and Ripling's equation measurement of compliance. The experimental results represent that the relation between interfacial crack length for the ultrasonic attenuation coefficient and energy release rate is increased proportionally. From the experimental results, a measurement method of the interfacial crack length by the ultrasonic attenuation coefficient was proposed and discussed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.66-72
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• 2012

Ultrasonic metal welder is consisted of power supply, transducer, booster, and horn. Precise designing is required since each part's shape, length and mass can affect driving frequency and vibration mode. This paper gives a description of an experimental study of the ultrasonic welding of metals. A horn suitable for 40,000Hz was attached to the ultrasonic metal welder in order to weld Cu sheet. The Cu sheet welding was done with different amplitude, pressure and welding time, and its maximum tension was measured. Maximum tension of 177.99N was obtained when the pressure was 2.5bar, amplitude was 80%, and welding time was 0.34sec. Therefore, excessive welding condition negatively influences maximum tension measurement result.

• Journal of Welding and Joining
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• v.16 no.2
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• pp.48-56
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• 1998

This study was performed to find the best bonding conditions by comparing mechanical properties in thermoplastic resin of polyethylene (PE) and polyamide (PA) adhesion. Following results were obtained from the tests with varying welding time and welding pressure. Satisfactory adhesion was executed in ultrasonic welding for the same materials of PE and PA. The best welding conditions were found to be welding time of 1 second, welding pressure of 250kPa for PE-PE weding, 2 second and 350kPa for PA-PA welding. Welding time and welding pressure end to increase with the increase of materials strength. Dissimilar materials were adhered when adhesion and ultrasonc welding were performed simultaneously. The observation of the structure of ultrasonic welding area with microscope showed differenticated structures between well adhered region and badly adhered region.