Junyong Park

Analysis of external force dependent lumped RLGC model of high-bandwidth and high-density silicone rubber socket

In this paper, structural and electrical characteristic deviations of silicone rubber sockets are analyzed depending on external force based on its lumped RLGC model. Electrical performances heavily depend on compression rate of the silicone rubber socket. Thus, study on the structural and electrical characteristic deviations of the silicone rubber socket depending on external force is needed for reliable tests. The deviations are analyzed based on an assumption based simplified equivalent model of the silicone rubber socket. For verification, a 3D electromagnetic (EM) simulation program is used and its results are compared with that of proposed RLGC models in the frequency domain. The electrical performance of the RLGC model is nearly identical to that of 3D EM simulation result. In addition, the electrical performance of the compressed silicone rubber socket is also nearly identical to that of a solder ball when it is compressed at different compression ratio.

Modeling and analysis of a conductive rubber contactor for package test

For high-speed package testing, conductive rubber contactors become more and more promising because of its excellent RF performance. For electrical characteristic analysis of the conductive rubber contactor, the lumped equivalent circuit model of conductive rubber contactor based on its physical dimension and structure is proposed and verified with 3D field and SPICE simulation.

Signal Integrity Design and Analysis of a Multilayer Test Interposer for LPDDR4 Memory Test With Silicone Rubber-Based Sheet Contact

As the data rate of Low Power Double Data Rate 4 (LPDDR4) memory now exceeds 3.2 Gb/s, it is becoming more difficult to meet the target specifications. While testing has become of utmost importance, it is not viable to have a direct access to the signal pins in a package on package configuration due to the densely located array of solder balls; instead, a test interposer with an excellent electrical performance needs to be adopted to provide test access. In this paper, we first propose a novel test interposer scheme for testing LPDDR4 memory packages. For accurate testing without significant influence on the intrinsic signal path, the proposed test interposer is designed considering a number of signal integrity issues such as intersymbol interference, jitter, impedance matching, and crosstalk. Furthermore, by adopting silicone rubber sheet in place of soldering, the proposed test interposer enhances reusability of the packages with a fast setup time. Moreover, a reconstruction method is proposed that can reconstruct the voltage at application processor using the waveform captured on the test interposer, instead of probing at the ball gray array directly. Through a series of simulations and measurements, we experimentally verified the proposed test interposer. The proposed test interposer scheme can be widely adopted for testing of high-performance packages with its high accuracy and practicality.

Through-Silicon Via Capacitance–Voltage Hysteresis Modeling for 2.5-D and 3-D IC

We propose, for the first time, an explicit semiconductor physics-based through-silicon via (TSV) capacitance–voltage (CV) model. The effect of TSV CV hysteresis is demonstrated in the model, and the TSV capacitance is modeled with respect to dc bias voltage and the dimension of the TSV. The proposed model is verified by comparison to the measurement results. The effect of hysteresis in the model correlates well with the measurement results. This model can be utilized in a circuit level simulation to expand the possible application of the model to, but not limited to, hierarchical power distribution network impedance analysis, RC delay analysis, input–output power consumption analysis, and crosstalk and eye diagram simulation in any 3-D-IC systems using TSVs.

Design and analysis of silicone rubber-based TERAPOSER for LPDDR4 memory test

Motivated by the increasing market demand for the high performance mobile devices, both the data rate and the number of pin of mixed-signal systems keep on increasing to realize multifunctional yet compact system designs. With this ascending technical trend, many signal integrity (SI) and power integrity (PI) problems such as ISI, jitter, crosstalk, simultaneous switching noise (SSN) have arisen that need to be thoroughly analyzed and tested. In order to accurately monitor the data signals of LPDDR4, a carefully designed test interposer considering such factors as impedance matching, minimization of skew and crosstalk needs to be proposed. In this paper, a novel test interposer scheme composed of a test interposer and silicone rubber sheets is proposed for LPDDR4 memory test. Through a series of simulations and measurements, we experimentally verify the proposed structures in time and frequency domains, and prove their accuracy and practicality.

Generation of magnetic propulsion force using wireless power transfer coil

A micro-robot is a promising device for minimally invasive surgery or drug delivery inside of the body for medical purpose. Due to its small size, the micro robot should float in the blood vessel to destination. Therefore, the propulsion mechanism of micro-robot have become an active area of study these days [1][2]. Recent studies of the propulsion of these robots have focused on the insertion of permanent magnets with Helmholtz coil which can generate magnetic field for propulsion of the micro-robot. However, this type of propulsion system has limited in that the DC magnetic field delivers propulsion but does not deliver any electric power to the robot [3]. Inevitably, the micro-robot only perform limited mission-like drilling and moving without any electric power sources [4]. If propulsion and power can be delivered to the micro-robot at the same time, the robot can contain active devices and can thus perform much more complex and important medical missions.

Design of active connector for high speed serial link interconnection

In this paper, an active connector is designed and simulated for high speed serial link interconnection. The connector design consists of three main parts; plug, receptacle, and paddle board. For achieving high bandwidth performance, the key difference of the proposed connector, comparison to the general connector structure, is that the active equalizer is integrated on the paddle board. The connector model is designed and simulated for this study, and the result shows this proposed connector structure is good for high bandwidth interconnection up to 20 Gbps.

Miniaturization of electromagnetic bandgap structures for noise suppression

Advancement in semiconductor technologies including CMOS and SiGe is enabling the commercialisation of devices that have increased switching speed, reduced power supply and increased circuit complexity. Proliferation of high-speed systems in both digital and mixed-signal applications is also driving the need for advanced noise suppression techniques. This paper describes a novel approach of using miniaturized electromagnetic bandgap structures. By leveraging on low shrinkage composite ceramics technology to increase the dielectric loading of the EBG structures, we have achieved significant improvement in the bandwidth and start frequency of more than 30% and 90%, respectively, when compared with conventional approaches.

Thin Hybrid Metamaterial Slab With Negative and Zero Permeability for High Efficiency and Low Electromagnetic Field in Wireless Power Transfer Systems

Current wireless power transfer (WPT) systems have limited charging distance and high induced electromagnetic field (EMF) leakage. Thus, we first proposed a thin printed circuit board (PCB) type hybrid metamaterial slab (HMS) combining two kinds of metamaterial cell structures. The metamaterial cells in the center area of the HMS have zero relative permeability and straighten the magnetic field direction. The metamaterial cells located at the edges of the HMS have negative relative permeability and change the outgoing magnetic fields to opposite direction by magnetic boundary condition. Therefore, the magnetic field can be more confined between transmitter and receiver coils, enhancing the power transfer efficiency, while decreasing the EMF leakage in a WPT system. In this paper, we demonstrated that increased power transfer efficiency from 34.5% to 41.7% and reduced EMF leakage from −19.21 to −26.03 dBm in 6.78-MHz WPT system. Furthermore, we proposed new analysis method for relative permeability measurement of the metamaterial using a novel cubic structure with perfect electrical conductor and perfect magnetic conductor boundary.

Design and verification of a high-speed connector for multi-media system

Recently, the number of high-definition media devices such as 8K ultra high-definition (UHD) TV and virtual reality (VR) is rapidly increasing. These multimedia systems require higher data rates for high resolution and versatility. With this increasing technical trend, high-speed connectors and cables are also becoming important. In this paper, we propose a highspeed connector that can transmit high-speed media data. The previous connectors have focused only on a physical connection and a mechanical reliability. However, as the data rate is increased, electrical performances of the connector have also become highly important. Therefore, signal integrity (SI) analysis for insertion loss, attenuation-to-crosstalk ratio (ACR), and impedance mismatch become essential for the high-speed connector. For verification, the 3D EM simulation tool is used to compare the performance of the previous and proposed connector. In conclusion, the proposed high-speed connector has better electrical performances than that of the previous connector.