초음파 분무공정에 의한 표면실장용 Solder Ball 제조에 관한 연구

Abstract

전자기기의 소형, 경량화와 고기능, 고성능화의 요구에 의해 배선기판에 고밀도로 실장하는 실장기술(surface mounting technology, SMT)이 요구되고 있다. 이러한 고밀도화에 발맞춰 등장한 것이 BGA( Ball Grid Array)기술이다. 이 BGA package 기술에 사용되는 Solder Ball 들은 많은 방법(melting cut solder wires, centrifugal atomization, …)으로 제조되고 있다. 본 연구에서는 ultrasonic atomization 방법을 이용하여 액적 형성에 있어서의 인자들을 변화시킬 때 액적 거동에 미치는 영향을 분석하고 균일한 액적 제조의 최적조건을 규명하고자 하였다. 연구 결과, 낮은 비용으로 높은 표면조도, 높은 진구도 목표직경의 ±3% 이내의 좁은 입도분포, 균일한 미세조직, 및 균일한 remelting 특성을 갖는 Sn-37%Pb 합금의 Solder Ball을 얻을 수 있었다.

As the microelectronics industry rapidly progresses toward miniaturized, high-performance devices, chip packages with higher input/output(I/O) connections are required. One solution to this ever-demanding requirement is the BGA package, a type of surface mount chip package. In this study, we have found that mono-sized balls of the eutectic Sn-37%Pb alloy was produced by controlling the break-up of a continuous laminar jet into uniform droplets and by rapidly solidifying the droplets in a silicon oil bath. We successfully fabricated solder balls, which have high sphericity, narrow size distribution(within ±3% of the targer diameter), uniform. rapidly solidified microstructures, and uniform re-melting characteristics due to their homogeneous microstructures using PAP(pulsated atomization process).

As the microelectronics industry rapidly progresses toward miniaturized, high-performance devices, chip packages with higher input/output(I/O) connections are required. One solution to this ever-demanding requirement is the BGA package, a type of surface mount chip package. In this study, we have found that mono-sized balls of the eutectic Sn-37%Pb alloy was produced by controlling the break-up of a continuous laminar jet into uniform droplets and by rapidly solidifying the droplets in a silicon oil bath. We successfully fabricated solder balls, which have high sphericity, narrow size distribution(within ±3% of the targer diameter), uniform. rapidly solidified microstructures, and uniform re-melting characteristics due to their homogeneous microstructures using PAP(pulsated atomization process).