Geometry Design of Vertical Probe Needle using Mechanical Testing and Finite Element Analysis

Kwon, Hyock-Ju,Lee, Jiwon,Shin, Bonghun,Jeon, Soo,Han, Chung Su,Im, Chang Min Korean Society for Precision Engineering 2014 International Journal of Precision Engineering and Vol.15 No.11

In wafer probing, probe needles provide the physical contact between the wafers and the probe card. During the contact process, the shape of the probe needle and the mounting configuration onto the probe card has large influences on the stresses and contact force that the probe needles experience. In this paper, static performance of a vertical-type probe needle integrated with floating mount technology was analyzed with a nonlinear finite element analysis. The geometry of a vertical probe needle was optimized in order to minimize the stress that occurs during the overdrive process, while maintaining adequate force for proper contact with the wafer. Maximum stress and contact force were formulated using the coefficients of 4th order polynomial representing the shape of cobra body, and then curvature of the probe needle body was optimized by applying the constrained minimization function to these functions. The maximum stress in the vertical probe pin at <TEX>$125{\mu}m$</TEX> overdrive was reduced from 972 MPa to 666 MPa by employing the probe needle with optimized geometry. The optimized design also induced the contact force of 5.217 gf, which is in the range of the required contact force of 5 to 8 gf.

Strain Ratio vs. Modulus Ratio for the Diagnosis of Breast Cancer Using Elastography

Hyock Ju Kwon,Bonghun Shin,Darindra Gopaul,Samantha Fienberg 대한의용생체공학회 2014 Biomedical Engineering Letters (BMEL) Vol.4 No.3

Purpose In elastography, strain ratio is commonly used as anindicator to detect the malignancy of the lesion, based onpalpation principle that pathological lesions are normallystiffer than benign tissues. We investigated the validity ofstrain ratio by comparing it with modulus ratio which is atrue indicator of the malignancy. Methods Strains inside the lesion and the tissue undercompressive loading were predicted by Eshelby’s solutionwhich is an analytical method to derive the elastic fieldwithin and around an ellipsoidal inclusion embedded in thematrix. Analytical results were also confirmed with finiteelement analysis (FEA) simulations. Results The analyses using Eshelby’s solution demonstratedthat strain ratio not only significantly underestimates themodulus ratio which is the true indicator of malignancy, butalso varies with other factors such as the shape and thestiffness of the inclusion. Based on the results from Eshelby’ssolution and FEA, we proposed a surface regression modelas a cubic polynomial function of strain ratio and ellipticityof the lesion to predict the modulus ratio. Conclusions The proposed model has been successfullyapplied to gelatin phantoms mimicking breast cancers andclinical ultrasound images of human breasts containingdifferent types of lesions. This study suggests the potential of the modulus ratio predicted by the model as a new indicator in differentiating malignant tumors from benign lesions.

인공지능 기술의 비파괴 검사 분야 응용

권혁주(Hyock Ju Kwon) 한국비파괴검사학회 2021 한국비파괴검사학회 원자력/전자기분과 하계 학술대회 초록집 Vol.2021 No.7

Fatigue Life Estimation of Vertical Probe Needle for Wafer Probing

Bonghun Shin,Hyock Ju Kwon,한상욱,임창민 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

Wafer probing is a core inspection process to detect defects in a wafer prior to packaging. Since probe card requires over a million touchdowns on wafers, service life of the probe needle is a critical factor in probe card design. For the prediction of service life, fatigue life estimation model should be developed first through fatigue testing with actual probe needles. However, standard fatigue test method cannot be adopted due the complexity in the mounting method and the geometry of probe needles. In this paper, a new fatigue test method for vertical probe needle with floating mount technology is proposed. By applying the method to the fatigue tests with actual probe needles, a stress-life estimation model is developed as a probe card design reference. The maximum Mises stress is determined as a primary variable of the model using a nonlinear finite element analysis simulation that considers both material and geometrical nonlinearity. The simulation results are verified by comparing the reaction forces from experiments and FEA. The fatigue fracture surfaces are observed with scanning electron microscopy to understand the fatigue failure mechanism in the probe needle.

Fatigue Life Estimation of Vertical Probe Needle for Wafer Probing

Shin, Bonghun,Kwon, Hyock-Ju,Han, Sang-Wook,Im, Chang Min Korean Society for Precision Engineering 2015 International Journal of Precision Engineering and Vol.16 No.12

Wafer probing is a core inspection process to detect defects in a wafer prior to packaging. Since probe card requires over a million touchdowns on wafers, service life of the probe needle is a critical factor in probe card design. For the prediction of service life, fatigue life estimation model should be developed first through fatigue testing with actual probe needles. However, standard fatigue test method cannot be adopted due the complexity in the mounting method and the geometry of probe needles. In this paper, a new fatigue test method for vertical probe needle with floating mount technology is proposed. By applying the method to the fatigue tests with actual probe needles, a stress-life estimation model is developed as a probe card design reference. The maximum Mises stress is determined as a primary variable of the model using a nonlinear finite element analysis simulation that considers both material and geometrical nonlinearity. The simulation results are verified by comparing the reaction forces from experiments and FEA. The fatigue fracture surfaces are observed with scanning electron microscopy to understand the fatigue failure mechanism in the probe needle.

Assessment of Geometrical Features of Internal Flaws with Artificial Neural Network

Salman Lari,Yanjun Qian,Hyock Ju Kwon 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.5

In nondestructive testing (NDT), geometrical features of a flaw embedded in the material such as its location, length, and orientation are critical factors to assess the severity of the flaw and make post-manufacturing decisions to improve the design. In this study, artificial intelligence (AI) based NDT approach was applied to the ultrasonic oscillograms obtained from virtual ultrasonic NDT to estimate geometrical features of a flaw. First, a numerical model of NDT specimen was constructed using acoustic finite element analysis (FEA) to produce the ultrasonic signals. The model was validated by comparing the simulated signals produced from the numerical model with the experimental data from actual NDT tests. Then, 750 numerical models containing flaws with different locations, lengths, and orientation angles were generated by FEA. Next, the oscillograms produced by the models were divided into 3 datasets: 525 for training, 113 for validation, and 112 for testing. Training inputs of the network were parameters extracted from ultrasonic signals by fitting them to sine functions. Lastly, to evaluate the network performance, outputs of the network including flaw’s location, length, and angle were compared with the desired values for all datasets. Deviations of the outputs from desired values were calculated by a regression analysis. Statistical analysis was also performed by measuring root mean square error (RMSE) and efficiency. RMSE in x-location, y-location, length, and angle estimations are 0.09 mm, 0.19 mm, 0.46 mm, and 0.75°, with efficiencies of 0.9229, 0.9466, 0.9140, and 0.9154, respectively for the testing dataset. Results suggest that the proposed AI-based method has the potential to interpret the oscillograms from ultrasonic NDT to estimate geometrical features of flaws embedded in the material.

투석환자의 진료권 이동에 영향을 미치는 요인

김민경 ( Min Kyoung Kim ),권순길 ( Soon Kil Kwon ),최웅 ( Woong Choi ),탁양주 ( Yang Ju Tak ),박종혁 ( Jong-hyock Park ),강길원 ( Kil Won Kang ) 한국보건경제정책학회(구 한국보건경제학회) 2020 보건경제와 정책연구 Vol.26 No.4

본 연구는 대표성 있는 자료를 활용한 투석환자의 진료권 이동 현황 및 이에 미치는 영향 요인 분석을 바탕으로 향후 투석 환자의 효율적인 의료이용을 위한 관리 정책에 참고자료가 될 수 있는 정보를 제공하고자 한다. 이를 위해 2003년~2015년까지 건강보험수급자의 자격 및 청구자료, 의료기관자료, 대한신장학회자료, 통계청자료를 활용하여 데이터베이스를 구축하고 분석에 활용하였으며, 개인, 의료기관, 지역사회특성에 따라 투석환자의 진료권 이동에 영향을 미치는 요인을 파악하기 위하여 다수준로지스틱 회귀분석을 하였다. 투석환자의 특성요인으로 남자, 29세 이하의 연령, 소득 9~10분위, 복막투석을 하는 경우 거주지역과 투석지역이 불일치하였고, 동반상병지표가 낮을수록, 입내원일수가 짧을수록 거주지역과 투석지역이 일치하였다. 의료기관요인으로 요양병원을 이용하는 경우 거주지역과 투석지역이 불일치하였고, 병상수가 적을수록 거주지역과 투석지역이 일치하였다. 지역사회요인으로 지역투석기수가 많을수록, 재정자주도가 높을수록, 고령인구비율이 높을수록, 인구밀도가 높을수록 거주지역과 투석지역이 일치하였다. 따라서 투석환자는 대진료권보다 중진료권 위주의 자원 배분과 지리적 인접성을 높이기 위해 진료권을 재편성함으로써 진료권간 연계를 통하여 의료이용의 지역적 불균형 문제를 해결할 수 있도록 정책적인 지원이 필요하다. This study attempts to fill this gap by analyzing the migration of dialysis patients between medical service regions and the underlying factors influencing the migration, thereby providing a reference data for future medical services management policy of dialysis patients. The database for the analysis was established by using the qualification and insurance claim data of health insurance recipients, medical institution data, Korean Society of Nephrology data and national statistical office data, from 2003 to 2015. The effect of the Migration of Dialysis Patients between Medical Service Regions on individual, medical institutions and community characteristics were analyzed by multilevel logistic regression analysis. There is greater inconsistency between the residential and medical service regions for dialysis patients who are male, under 29 years old, belong in the 9th-10th income quintile, and are performing peritoneal dialysis, while there is greater consistency if the co-morbidity index is lower and periods of staying in or visiting hospitals are shorter. In terms of medical institution factors, greater inconsistency is exhibited if patients use care hospitals, and greater consistency with lower number of beds. For the local social factors, consistency increases with a higher number of dialyzers and higher financial independence, a greater ratio of aging population and population density. To conclude, political support is required to resolve the imbalance in medical services by reorganizing the medical service boundaries and enhancing the geographical proximity and resource distribution to patients around medium-sized medical service regions rather than large ones.