3D reconstruction and defect pattern recognition of bonding wire based on stereo vision

Non-destructive detection of wire bonding defects in integrated circuits(IC)is critical for ensuring product quality after packaging.Image-processing-based methods do not provide a detailed evaluation of the three-dimensional defects of the bonding wire.Therefore,a method of 3D reconstruction and pattern recognition of wire defects based on stereo vision,which can achieve non-destructive detection of bonding wire defects is proposed.The contour features of bonding wires and other electronic components in the depth image is analysed to complete the 3D reconstruction of the bonding wires.Especially to filter the noisy point cloud and obtain an accurate point cloud of the bonding wire surface,a point cloud segmentation method based on spatial surface feature detection(SFD)was proposed.SFD can extract more distinct features from the bonding wire surface during the point cloud segmentation process.Furthermore,in the defect detection process,a directional discretisation descriptor with multiple local normal vectors is designed for defect pattern recognition of bonding wires.The descriptor combines local and global features of wire and can describe the spatial variation trends and structural features of wires.The experimental results show that the method can complete the 3D reconstruction and defect pattern recognition of bonding wires,and the average accuracy of defect recognition is 96.47%,which meets the production requirements of bonding wire defect detection.

A New Three-dimensional Network Constructed by Heptamolybdate, Sodium Ions and Hexamethylene Tetramine Cations via Hydrogen Bonds

The crystal structure of the title compound [Na2(OH2)5]2+[C6H12N4H2]2-2+ [Mo7O24]6 ?4H2O, prepared from an aqueous solution of Na2MoO4 ?2H2O in the presence of MoCl3 and hexamethylene tetramine, has been determined by single-crystal X-ray diffraction. The crystal is of orthorhombic, space group Pnma with a = 14.6113(2), b = 18.6833(1), c = 15.3712(2), V = 4196.14(8)3, Z = 4, Mr = 1548.13, F(000) = 3016, = 2.157 mm-1 and Dc = 2.451 g/cm3. The final R factor is 0.0526 for 3818 unique observed reflections (I > 2(I)). The structural analysis reveals that heptamolybdate anions in the title compound consist of seven edge-sharing MoO6 octahedra, and are linked into a three-dimensional framework by sodium ions and hydrogen bonds.

Hydrogen-bonded Three-Dimensional Networks Encapsulating One-dimensional Covalent Chains: [Cu(3-ampy)(H_2O)_4](SO_4)·(H_2O) (3-ampy = 3-Aminopyridine)

A three-dimensional complex [Cu（3-ampy）（HEO）4]（SO4）·（H2O） （3-ampy = 3-amino- pyridine） has been synthesized. Crystallographic data： C5H16CuN2O9S, Mr = 343.80, triclinic, space group P1, a = 7.675（2）, b = 8.225（3）, c = 10.845（3）A, α= 86.996（4）, β = 76.292（4）, γ= 68.890（4）°, V = 620.0（3）A^3, Z = 2, Dc = 1.841 g/cm^3, F（000） = 354 and μ = 1.971 mm^-1. The structure was refined to R = 0.0269 and wR = 0.0659 for 1838 observed reflections （I 〉 2a（/））. The structure consists of [Cu（3-ampy）（H2O）4]^2＋ cations, SO4^2- anions and lattice water molecules. 3-Ampy acting as a bidentate bridging ligand generates a 1D covalent chain. A supramolecular 2D framework is formed through π-π stacking of pyridine rings. The lattice water molecules and SO4^2- anions are located between the adjacent 2D frameworks. The hydrogen bonding interactions from lattice water molecules and SO4^2- anions to coordinate water extend the 2D framework into a 3D network.

Structure and Bonding in Some Gd(Ⅲ) Metal Complexes Studied by Three-Dimensional X-Ray Analysis and ^(155)Gd Mssbauer Spectroscopy

Some functional lanthanide metal complexes, such as acetylacetonato complexes, ethylenediaminetetraacetato complexes, were successfully applied for diagnostic technique. The authors are interested in investigating the structure and bonding in lanthanide and actinide metal complexes using 166Er, t55Gd, and 237Np Mtissbauer spectroscopies in connection with single-crystal and/or powder X-ray diffraction, making clear the differences on their structures as well as the differences in the participation of 4f and 5f orbitals in the chemical bonds. In this article, the crystal structures of two novel Gd（Ⅲ） acetylacetonato complexes, Gd（pta）3 · 2H2O （pta = 1,1,1 -trifluoro-5,5-dimethy 1-2,4-hexanedione） and Gd（bfa）3 · 2H2O （bfa = 1, 1, 1 -trifluoro-4-phenyl-2-4-butanedione） were reported. Though both of them were dihydrate and had distorted square antiprismatical structure, Gd（pta）3 · 2H2O crystallizes in the P 2 1/n （#14） monoclinic space group and its lattice parameters are a = 1.4141（6） nm, b = 1.0708（3） nm, c =2.2344（4） nm, β =952.4（2）°, and Gd（bfa）3· 2H2O crystallizes in P 212121 orthorhombic space group and its lattice parameters were a = 1.322 （1） nm, b = 2.295 （1） nm, c = 1. 0786（8） nm. In the meantime, the authors had finished a systematic investigation on the ^155Gd Mossbauer isomer shift （δ） of various Gd（Ⅲ） metal complexes having a different coordination number （C.N.） and different ratios coordinating oxygen to nitrogen. A tendency for the 6 value to decrease with an increase in the C.N, and the number of the nitrogen atom coordinating to Gd was confirmed. This indicated that the Gd-O and/or Gd-N bond in the investigated Gd（Ⅲ） metal complexes had a small covalent contribution, which was possible to be deduced from the O and/or N atoms of the lisands donating electrons to 6s, 5d, and 4f orbitals of Gd.

基于视觉技术的Wire Bonding中焊点质量的自动检测方法

用WireBonder(引线键合机)进行键合后的芯片,其焊点可能会出现位置偏移、断线和线尾(Pigtail)过长等缺陷。该文针对上述几种质量问题,利用WireBonder现有的硬件,运用图象处理及模式识别技术,提出了一套自动视觉检测的方法。实验表明,该方法所需硬件低廉,操作方便,能很好地检测WireBonding中焊点的质量。

Mechanism of microweld formation and breakage during Cu-Cu wire bonding investigated by molecular dynamics simulation

Currently,wire bonding is the most popular first-level interconnection technology used between the die and package terminals,but even with its long-term and excessive usage,the mechanism of wire bonding has not been completely evaluated.Therefore,fundamental research is still needed.In this study,the mechanism of microweld formation and breakage during Cu-Cu wire bonding was investigated by using molecular dynamics simulation.The contact model for the nanoindentation process between the wire and substrate was developed to simulate the contact process of the Cu wire and Cu substrate.Elastic contact and plastic instability were investigated through the loading and unloading processes.Moreover,the evolution of the indentation morphology and distributions of the atomic stress were also investigated.It was shown that the loading and unloading curves do not coincide,and the unloading curve exhibited hysteresis.For the substrate,in the loading process,the main force changed from attractive to repulsive.The maximum von Mises stress increased and shifted from the center toward the edge of the contact area.During the unloading process,the main force changed from repulsive to attractive.The Mises stress reduced first and then increased.Stress concentration occurs around dislocations in the middle area of the Cu wire.

Factors governing heat affected zone during wire bonding

In the wire bonding process of microelectronic packaging,heat affect zone(HAZ)is an important factor governing the loop profile of bonding.The height of loop is affected by the length of the HAZ.Factors governing the HAZ were studied.To investigate this relationship,experiments were done for various sizes of wire and free air ball(FAB).Electric flame-off(EFO)current, EFO time,EFO gap and recrystallization were also studied.The results show that as the size of FAB becomes larger,the length of HAZ increases.With the increase of EFO current and time,the length of HAZ becomes longer.When FAB forms at the same parameter the length of HAZ becomes shorter with the high temperature of recrystallization.

Temperature effect in thermosonic wire bonding

The temperature effect on bonding strength and ultrasonic transmission in a PZT transducer system was investigated. The results show that, the temperature change influences the material features of the bonding interface, such as elastic modulus, tensile strength of gold ball and Ag substrate, which results in different bonding strengths. Moreover, the temperature change also influences the impedance and dissipative ultrasonic energy in the PZT system. The current signal of PZT transducer was analyzed by join time-frequency analysis, which can reveal the current change in a bonding process more clearly and completely. The analysis shows that the bonding parameters influence mutually. These results can help build some criteria for parameter match and optimization in wire bonding processes.

Bonding mechanism of ultrasonic wedge bonding of copper wire on Au/Ni/Cu substrate

The ultrasonic wedge bonding with d25 μm copper wire was achieved on Au/Ni plated Cu substrate at ambient temperature.Ultrasonic wedge bonding mechanism was investigated by using SEM/EDX,pull test,shear test and microhardness test.The results show that the thinning of the Au layer occurs directly below the center of the bonding tool with the bonding power increasing.The interdiffusion between copper wire and Au metallization during the wedge bonding is assumed negligible,and the wedge bonding is achieved by wear action induced by ultrasonic vibration.The ultrasonic power contributes to enhance the deformation of copper wire due to ultrasonic softening effect which is then followed by the strain hardening of the copper wedge bonding.

New Type Gold Bonding Wire

The influences of additive elements on properties of gold wire and the technology of homogeneously adding those elements to gold matrix were studied. A BJ-type gold bonding wire for automatic bonders was developed, which has high bond strength and stable uniform mechanical properties and is capable of forming good spherical shape of melting-ball observed by SEM. The bonding wire is fully suitable to the requirements of the automatic bonding technology and satisfies the performance requirement of IC products.

Three-dimensional global interconnect based on a design window

Based on a stochastic wire length distributed model, the interconnect distribution of a three-dimensional integrated circuit （3D IC） is predicted exactly. Using the results of this model, a global interconnect design window for a giga-scale system-on-chip （SOC） is established by evaluating the constraints of 1） wiring resource, 2） wiring bandwidth, and 3） wiring noise. In comparison to a two-dimensional integrated circuit （2D IC） in a 130-nm and 45-nm technology node, the design window expands for a 3D IC to improve the design reliability and system performance, further supporting 3D IC application in future integrated circuit design.

Effect of Conduction Pre-heating in Au-Al Thermosonic Wire Bonding

This paper presents the recent study by investigating the vital responses of wire bonding with the application of conduction pre-heating. It is observed through literature reviews that, the effect of pre-heating has not been completely explored to enable the successful application of pre-heating during wire bonding. The aim of wire bonding is to form quality and reliable solid-state bonds to interconnect metals such as gold wires to metalized pads deposited on silicon integrated circuits. Typically, there are 3 main wire bonding techniques applied in the industry;Thermo-compression, Ultrasonic and Thermosonic. This experiment utilizes the most common and widely used platform which is thermosonic bonding. This technique is explored with the application of conduction pre-heating along with heat on the bonding site, ultrasonic energy and force on an Au-Al system. Sixteen groups of bonding conditions which include eight hundred data points of shear strength at various temperature settings were compared to establish the relationship between bonding strength and the application of conduction pre-heating. The results of this study will clearly indicate the effects of applied conduction pre-heating towards bonding strength which may further produce a robust wire bonding system.

Wire Bonding Using Offline Programming Method

Manual process of creating bonding diagram is known to be time consuming and error prone. In comparison, offline programming (OLP) provides a much more viable option to reduce the wire bonding creation time and error. OLP is available in two versions, i.e., vendor specific OLP and direct integration offline pro- gramming (Di-OLP). Both versions utilize the bonding diagram and computer aided design data to speed up bonding program creation. However, the newly proposed Di-OLP is more flexible as it can be used to create bonding program for multiple machine platforms in microelectronics industry. Some special features of Di-OLP method are presented. The application of generic OLP however, is applicable to machines that recognize ASCII text file. The user needs to know the data format accepted by machine and convert the data accordingly to suit its application for different machine platforms. Di-OLP is also a practical method to replace the time consuming manual method in production line.

New Generation Semi-Automatic Thermosonic Wire Bonder

The physical and technological aspects of wire ball-wedge bonding in the assembly of integrated circuits are considered.The video camera and the pattern recognition system(PRS)of new bonder helps to provide accurate positioning of the bonding tool on the chip pads of integrated circuits.The formation of the loop wire cycle is ensured by the synchronous movement of the bonding head along the Z axis and the working table along the XY axes based on the servo drive.A feature of the bonder is that it can bond all the wire loops of the electronic device according to the pre-recorded program without needing to align the bonding points.

功率器件芯片自发热对水汽入侵的抑制作用

为探究高温高湿环境中功率器件芯片自发热现象对水汽入侵的抑制作用机理及其对功率器件静态参数和封装可靠性的影响,将器件分成三组进行功率循环测试对比实验。第一组器件直接进行功率循环测试;第二组器件在60℃/85%RH环境储存1000 h再进行功率循环测试;第三组器件在60℃/85%RH环境储存1000 h期间导通电流,令芯片自发热模拟实际工况(芯片结温为120℃),然后进行功率循环测试。实验结果显示,水汽入侵会使功率器件的静态参数发生漂移,缩短器件功率循环寿命。器件功率循环寿命缩短的原因是水汽入侵腐蚀了器件键合线,影响了键合线可靠性。功率器件芯片自发热可以抑制水汽入侵,减小由水汽入侵导致的静态参数漂移及其对器件键合线的腐蚀作用。

In vivo biofilm formation on stainless steel bonded retainers during different oral health-care regimens

Retention wires permanently bonded to the anterior teeth are used after orthodontic treatment to prevent the teeth from relapsing to pre-treatment positions. A disadvantage of bonded retainers is biofilm accumulation on the wires, which produces a higher incidence of gingival recession, increased pocket depth and bleeding on probing. This study compares in vivo biofilm formation on single-strand and multi-strand retention wires with different oral health-care regimens. Two-centimetre wires were placed in brackets that were bonded to the buccal side of the first molars and second premolars in the upper arches of 22 volunteers. Volunteers used a selected toothpaste with or without the additional use of a mouthrinse containing essential oils. Brushing was performed manually. Regimens were maintained for 1 week, after which the wires were removed and the oral biofilm was collected to quantify the number of organisms and their viability, determine the microbial composition and visualize the bacteria by electron microscopy. A 6-week washout period was employed between regimens. Biofilm formation was reduced on single-strand wires compared with multi-strand wires; bacteria were observed to adhere between the strands. The use of antibacterial toothpastes marginally reduced the amount of biofilm on both wire types, but significantly reduced the viability of the biofilm organisms. Additional use of the mouthrinse did not result in significant changes in biofilm amount or viability. However, major shifts in biofilm composition were induced by combining a stannous fluoride- or triclosan-containing toothpaste with the mouthrinse. These shifts can be tentatively attributed to small changes in bacterial cell surface hydrophobicity after the adsorption of the toothpaste components, which stimulate bacterial adhesion to the hydrophobic oil, as illustrated for a Streptococcus mutans strain.

Effect of ultrasonic power and bonding force on the bonding strength of copper ball bonds

Copper wire, serving as a cost-saving alternative to gold wire, has been used in many high-end thermosonic ball bonding applications. In this paper, the bond shear force, bond shear strength, and the ball bond diameter are adopted to evaluate the bonding quality. It is concluded that the ef/~cient ultrasonic power is needed to soften the ball to form the copper bonds with high bonding strength. However, excessive ultrasonic power would serve as a fatigue loading to weaken the bonding. Excessive or less bonding force would cause cratering in the silicon.

Determination of Surface Roughness in Wire and Arc Additive Manufacturing Based on Laser Vision Sensing

Wire and arc additive manufacturing(WAAM) shows a great promise for fabricating fully dense metal parts by means of melting materials in layers using a welding heat source. However, due to a large layer height produced in WAAM, an unsatisfactory surface roughness of parts processed by this technology has been a key issue. A methodology based on laser vision sensing is proposed to quantitatively calculate the surface roughness of parts deposited by WAAM.Calibrations for a camera and a laser plane of the optical system are presented. The reconstruction precision of the laser vision system is verified by a standard workpiece. Additionally, this determination approach is utilized to calculate the surface roughness of a multi-layer single-pass thin-walled part. The results indicate that the optical measurement approach based on the laser vision sensing is a simple and effective way to characterize the surface roughness of parts deposited by WAAM. The maximum absolute error is less than 0.15 mm. The proposed research provides the foundation for surface roughness optimization with different process parameters.

An optimal stacking order for mid-bond testing cost reduction of 3D IC

In order to solve the problem that the testing cost of the three-dimensional integrated circuit(3D IC)is too high,an optimal stacking order scheme is proposed to reduce the mid-bond test cost.A new testing model is built with the general consideration of both the test time for automatic test equipment(ATE)and manufacturing failure factors.An algorithm for testing cost and testing order optimization is proposed,and the minimum testing cost and optimized stacking order can be carried out by taking testing bandwidth and testing power as constraints.To prove the influence of the optimal stacking order on testing costs,two baselines stacked in sequential either in pyramid type or in inverted pyramid type are compared.Based on the benchmarks from ITC 02,experimental results show that for a 5-layer 3D IC,under different constraints,the optimal stacking order can reduce the test costs on average by 13%and 62%,respectively,compared to the pyramid type and inverted pyramid type.Furthermore,with the increase of the stack size,the test costs of the optimized stack order can be decreased.

EFFECT OF ULTRASONIC POWER ON THE HEAVY ALUMINUM WEDGE BONDING STRENGTH

Eleven groups of wire bonding experiments are carried out on an experiment platform （restructured with a U3000 heavy aluminum wedge wire bonder）. Pure silicon aluminum wire （300 μm in diameter, 2.94-3.92 N in average pull force） and nickel coated aluminum substrates are used in the experiments. During the experiment process, only ultrasonic power rate parameter is changed and the other bonding parameters are kept as constant, The bonding force and time are 4.90 N and 100 ms respectively. After the bonding experiments, shear strength tests are carried out on the bonds as the bonding strength criterion. From those experiments and test results, some conclusions are obtained： In the small ultrasonic power rate conditions （about 20%-30%）, with the power increasing, the bonding strength enhances accordingly; However, in the large ultrasonic power rate conditions （about 45%-70%）, the bonding strength decreases accordingly and over bonding happens. Only when the ultrasonic power rate is in a moderate condition （about 35%-40%） can good and stabilized bonding strength be acquired.