Controlled Trigger and Image Restoration for High Speed Probe Card Analysis

Bonghun Shin,Soo Jeon,이지원,한충수,임창민,권혁주 한국정밀공학회 2015 International Journal of Precision Engineering and Vol.16 No.4

Latency and image blurring are major limitations of machine vision processes, which often require every target object to pause fora moment for capturing and processing a still image. When a large number of objects are to be inspected, such a stop-and-goapproach may significantly degrade the test efficiency due to a long inspection time. This paper investigates the performance anderror analysis of dynamic imaging approach where the image is captured and processed on-the-fly while the target object is stillmoving. Taking images of a moving object can substantially enhance the inspection speed but intensifies latency and image blurring. To overcome these issues, firstly, we implement the controlled trigger, i.e., to operate the machine vision in synchrony with the positionsensing while the target object is moving. Then, we attempt to restore the blurred pixel data through advanced image restorationtechniques. The main ideas are applied to a semiconductor test process called the probe card analysis and its performance isexperimentally verified.

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.

Elastography for portable ultrasound

Bonghun Shin,Soo Jeon,류정원,권혁주 대한의용생체공학회 2018 Biomedical Engineering Letters (BMEL) Vol.8 No.1

Portable wireless ultrasound has been emergingas a new ultrasound device due to its unique advantagesincluding small size, lightweight, wireless connectivity andaffordability. Modern portable ultrasound devices can offerhigh quality sonogram images and even multiple ultrasoundmodes such as color Doppler, echocardiography, andendovaginal examination. However, none of them canprovide elastography function yet due to the limitations incomputational performance and data transfer speed ofwireless communication. Also phase-based strain estimator(PSE) that is commonly used for conventional elastographycannot be adopted for portable ultrasound, because ultrasoundparameters such as data dumping interval are variedsignificantly in the practice of portable ultrasound. Therefore,this research aims to propose a new elastographymethod suitable for portable ultrasound, called the robustphase-based strain estimator (RPSE), which is not onlyrobust to the variation of ultrasound parameters but alsocomputationally effective. Performance and suitability ofRPSE were compared with other strain estimators includingtime-delay, displacement-gradient and phase-basedstrain estimators (TSE, DSE and PSE, respectively). Threetypes of raw RF data sets were used for validation tests:two numerical phantom data sets modeled by an openultrasonic simulation code (Field II) and a commercialFEA (Abaqus), and the one experimentally acquired with aportable ultrasound device from a gelatin phantom. Toassess image quality of elastograms, signal-to-noise(SNRe) and contrast-to-noise (CNRe) ratios were measuredon the elastograms produced by each strain estimator. Thecomputational efficiency was also estimated and compared. Results from the numerical phantom experiment showedthat RPSE could achieve highest values of SNRe andCNRe (around 5.22 and 47.62 dB) among all strain estimatorstested, and almost 10 times higher computationalefficiency than TSE and DSE (around 0.06 vs. 5.76 s perframe for RPSE and TSE, respectively).

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.

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

권혁주,이지원,Bonghun Shin,Soo Jeon,Chung Su Han,임창민 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.

In wafer probing, probe needles provide the physical contact between the wafers and the probe card. During the contact process, theshape of the probe needle and the mounting configuration onto the probe card has large influences on the stresses and contact forcethat the probe needles experience. In this paper, static performance of a vertical-type probe needle integrated with floating mounttechnology was analyzed with a nonlinear finite element analysis. The geometry of a vertical probe needle was optimized in orderto 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 cobrabody, 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 125 μm overdrive was reduced from 972 MPa to 666 MPa by employing the probeneedle with optimized geometry. The optimized design also induced the contact force of 5.217 gf, which is in the range of the requiredcontact 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.

형강 절단 로봇 시스템 개발

문승환(SeungHwan Mun),신봉헌(BongHun Shin),박기범(GiBeom Park),남미희(MiHee Nam),배성준(SeongJun Bae),KiHun Kim,HeeJin Lee,김대경(DaeKyung Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

Profile marking and cutting is one of jobs in shipbuilding. Therefore, the automation of the profile marking and cutting process in shipyards is vital to improve the productivity, and robots play an important role in it, giving an extra benefit of replacing the human labors in dangerous working environments. The profile line in shipbuilding is composed of 2 works: (ⅰ)Marking, and (ⅱ)Cutting. In the marking work, operators mark the part name, frame line, and bend line. And in the cutting work, operators cut an profile with accurate shape. The profile cutting robot system can be classified into 5 systems: (ⅰ)Cutting robot system to perform the cutting process, (ⅱ)Measuring robot system to move the profile for measuring process, (ⅲ)Printing system to mark the labeling, (ⅳ)control system to govern the machinery system for marking and cutting, and (ⅴ)management system to perform supporting roles such as running an off-line program and a monitoring program.

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.