• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.11a
• /
• pp.745-746
• /
• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.11a
• /
• pp.747-748
• /
• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.11a
• /
• pp.743-744
• /
• 2008

• Proceedings of the KIEE Conference
• /
• 2004.11c
• /
• pp.478-480
• /
• 2004

다이아몬드 톱날을 이용한 얇은 Si 웨이퍼의 기계적인 다이싱은 chipping, crack 등의 문제점을 발생시킨다. 또한 stacked die 나 multi-chip등과 같은 3D-WLP(wafer level package)에서 via를 생성하기 위해 현재 사용되는 화학적 etching은 공정속도가 느리고 제어가 힘들며, 공정이 복잡하다는 문제점을 가지고 있다. 이러한 문제점을 해결하기 위해 현재 연구되고 있는 분야가 레이저를 이용한 웨이퍼 다이싱 및 드릴링이다. 본 논문에서는 UV 레이저를 이용한 얇은 Si 웨이퍼 다이싱 및 드릴링 시스템에 대해 소개하고, 웨이퍼 다이싱 및 드릴링 실험결과를 바탕으로 적절한 레이저 및 공정 매개변수에 대해 설명한다.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.2
• /
• pp.13-19
• /
• 2010

Due to the rapid spread of mobile handheld devices, industrial demands for micro-scale holes with a diameter of even smaller than $10{\mu}m$ in sapphire/silicon wafers have been increasing. Holes in sapphire wafers are for heat dissipation from LEDs; and those in silicon wafers for interlayer communication in three-dimensional integrated circuit (IC). We have developed a sapphire wafer driller equipped with a 532nm laser in which a cooling chuck is employed to minimize local heat accumulation in wafer. Through the optimization of process parameters (pulse energy, repetition rate, number of pulses), quality holes with a diameter of $30{\mu}m$ and a depth of $100{\mu}m$ can be drilled at a rate of 30holes/sec. We also have developed a silicon wafer driller equipped with a 355nm laser. It is able to drill quality through-holes of $15{\mu}m$ in diameter and $150{\mu}m$ in depth at a rate of 100holes/sec.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2009.10a
• /
• pp.701-702
• /
• 2009

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.19 no.9
• /
• pp.825-831
• /
• 2006

As an increase of chip complexity and level of chip integration, chip input/output (I/O) pad pitches are also drastically reduced. With arrival of high complexity SoC (System on Chip) and SiP (System in Package) products, conventional horizontal type probe card showed its limitation on probing density for wafer level test. To enhance probing density, we proposed new vertical type probe card that has the $70{\mu}m$ probe needle with tungsten wire in $80{\mu}m$ micro-drilled hole in ceramic board. To minimize alignment error, micro-drilling conditions are optimized and epoxy-hardening conditions are also optimized to minimize planarity changes. To apply wafer level test for target devices (T5365 256M SDRAM), designed probe card was characterized by probe needle tension for test, contact resistance measurement, leakage current measurement and the planarity test. Compare to conventional probe card with minimum pitch of $50{\sim}125{\mu}m\;and\;2\;{\Omega}$ of average contact resistance, designed probe card showed only $22{\mu}$ of minimum pitch and $1.5{\Omega}$ of average contact resistance. And also, with the nature of vertical probing style, it showed comparably small contact scratch and it can be applied to bumping type chip test.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.2
• /
• pp.7-12
• /
• 2010

Due to the extremely short interaction time (< $10\times10^{-12}$sec) between laser pulse and material, which enables the minimization of heat affection, ultrafast laser micro-machining has rapidly widened its applications. In this paper, the characteristics of ultrafast laser micro-machining have been reviewed and experimentally demonstrated in laser drilling of silicon wafer and in laser cutting of rigid PCB.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.976-979
• /
• 2002

This research presents the new method to fabricate small features through applying chemical mechanical micro machining(C3M) for Al5052 and single crystal silicon. To improve machinability of ductile and brittle material, reacted layer was formed on the surface before micro-drilling process by chemical reaction with $HNO_3$(10wt%) and KOH(10wt%). And then workpieces were machined to compare conventional micro-drilling process with newly suggested one. To evaluate whether or not the machinability was improved by the effect of chemical condition, surface defects such as burr, chipping and crack generation were measured. Finally, it is confirmed that C3M is one of the feasible tools for micro machining with the aid of effect of the chemical reaction.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.12 no.2
• /
• pp.75-80
• /
• 2013

Cathode is an essential component used in plasma etching process which is to make micro pattern on the silicon wafer. The currently used cathodes produce particles at the high temperature plasma etching process. To overcome this problem, a 'Silicon Only Cathode' was developed. This 'Silicon Only Cathode' requires manufacturing process changes due to the change of shapes, material features, and machining characteristics of work materials. This research investigates the small hole drilling process. The conclusion is that PCD drills with twist angles of $20^{\circ}$ and $25^{\circ}$ were tested for small hole drilling and the experimental results indicate that the drill with $25^{\circ}$ twist angle drill causes less thrust force.