Plastic Ball Research Articles

40-Gb/s Package Design Using Wire-Bonded Plastic Ball Grid Array

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A 40-Gb/s packaging solution that uses low-cost wire-bonded plastic ball grid array (WB-PBGA) technology is presented. Since such a high speed was beyond the reach of conventional package designs, a new design methodology was proposed—discontinuity cancellation in both signal-current and return-current paths. The 3-D structures of bonding wires, vias, solder ball pads, and power distribution networks were optimized for the discontinuity cancellation. Two versions of four-layer WB-PBGA packages were designed; one according to the proposed methodology and the other conventionally. The proposed design methodology was verified with full-wave simulation, passive bandwidth measurement, time domain reflectometry (TDR), eye diagram measurement, and jitter analysis. </para>

Removal of vapour phase PCDD/Fs in electric arc furnace steelmaking emissions by sorption using plastics

Plastics are potentially suitable for the removal of vapour phase PCDD/Fs in emissions from the electric arc furnace (EAF) steelmaking process. Three different commercial plastics, i.e. polypropylene BE170MO (Borealis A/S, Denmark), polypropylene in the form of 5 mm spheres (The Precision Plastic Ball Co. Ltd., UK) and polyethylene LD605BA (ExxonMobil Chemical, Belgium), have been studied using a novel experimental apparatus for the removal of vapour phase PCDD/Fs. Polypropylene BE170MO was identified to be the most suitable product amongst the three plastics in terms of PCDD/F sorption and potential industrial application. The optimum temperature for PCDD/F sorption on polypropylene BE170MO was below 90 °C for a removal efficiency of >99% at an average vapour phase PCDD/F concentration of 3.5 ng I-TEQ/Nm 3. At 130 °C, 53% of the PCDD/Fs trapped on polypropylene BE170MO were desorbed.

Nano‐ and micro‐filled conducting adhesives for z‐axis interconnections: new direction for high‐speed, high‐density, organic microelectronics packaging

PurposeThe purpose of this paper is to discuss the use of epoxy‐based conducting adhesives in z‐axis interconnections.Design/methodology/approachA variety of conductive adhesives with particle sizes ranging from 80 nm to 15 μm were laminated into printed wiring board substrates. SEM and optical microscopy were used to investigate the micro‐structures, conducting mechanism and path. The mechanical strength of the various adhesives was characterized by 90° peel test and measurement of tensile strength. Reliability of the adhesives was ascertained by IR‐reflow, thermal cycling, pressure cooker test (PCT), and solder shock. Change in tensile strength of adhesives was within 10 percent after 1,000 cycles of deep thermal cycling (DTC) between −55 and 125°C.FindingsThe volume resistivity of copper, silver and low‐melting point (LMP) alloy based paste were 5 × 10−4, 5 × 10−5 and 2 × 10−5 Ω cm, respectively. Volume resistivity decreased with increasing curing temperature. Adhesives exhibited peel strength with Gould's JTC‐treated Cu as high as 2.75 lbs/in. for silver, and as low as 1.00 lb/in. for LMP alloy. Similarly, tensile strength for silver, copper and LMP alloy were 3,370, 2,056 and 600 ψ, respectively. There was no delamination for silver, copper and LMP alloy samples after 3X IR‐reflow, PCT, and solder shock. Among all, silver‐based adhesives showed the lowest volume resistivity and highest mechanical strength. It was found that with increasing curing temperature, the volume resistivity of the silver‐filled paste decreased due to sintering of metal particles.Research limitations/applicationsAs a case study, an example of silver‐filled conductive adhesives as a z‐axis interconnect construction for a flip‐chip plastic ball grid array package with a 150 μm die pad pitch is given.Originality/valueA high‐performance Z‐interconnect package can be provided which meets or exceeds JEDEC level requirements if specific materials, design, and manufacturing process requirements are met, resulting in an excellent package that can be used in single and multi‐chip applications. The processes and materials used to achieve smaller feature dimensions, satisfy stringent registration requirements, and achieve robust electrical interconnections are discussed.

마이크로 무아레 간섭계를 이용한 초정밀 변형 측정

Moire interferometry is an optical method, providing whole field contour maps of in-plane displacements with high resolution. The demand for enhanced sensitivity in displacement measurements leads to the technique of microscopic moire interferometry. The method is an extension of the moire interferometry, and employs an optical microscope for the required spatial resolution. In this paper, the sensitivity of moire interferometry is enhanced by an order of magnitude using an immersion interferometry and the optical/digital fringe multiplication(O/DFM) method. In fringe patterns, the contour interval represents the displacement of 52 ㎚ per fringe order. In order to estimate the reliability and the applicability of the optical system implemented, the measurements of rigid body displacements of grating mold and the coefficient of thermal expansion(CTE) for an aluminium block are performed. The system developed is applied to the measurement of thermal deformation in a flip chip plastic ball grid array package.

Damage Initiation and Propagation in Voided Joints: Modeling and Experiment

This study examines damage initiation and propagation in solder joints with voids, under thermomechanical cyclic loading. An accelerated thermal cycling test is conducted on printed wiring assemblies (PWAs) containing 256 input/output (I/O) plastic ball grid arrays (PBGAs) with voided solder joints. Destructive and nondestructive failure analyses of the solder balls are used to detect the presence of voids and to relate the extent of damage propagation to the number of thermal cycles. Particular cases of voided and damaged joints are selected from these tests, to guide the development of a strategy for modeling damage propagation, using a three dimensional global-local finite element analysis (FEA). The displacement results of the global FEA at the top and bottom of the selected solder balls are used as the boundary conditions in a local FEA model, which focuses on the details of damage initiation and propagation in the individual solder ball. The local model is error seeded with voids based on cases selected in experiment. The damage propagation rate is monitored for all the cases. The technique used to quantify cyclic creep-fatigue damage is a continuum model based on energy partitioning. A method of successive initiation is used to model the growth and propagation of damage in the selected case studies. The modeling approach is qualitatively verified using the results of the accelerated thermal cycling test. The verified modeling technique described above is then used for parametric study of the durability of voided solder balls in a ChipArray Thin Core BGA with 132 I/O (CTBGA132) assemblies, under thermal cycling. The critical solder ball in the package is selected and is error seeded with voids with different sizes and various distances from damage initiation site. The results show that voids in general are not detrimental to thermal cycling durability of the CTBGA132 assembly, except when a large portion of the damage propagation path is covered with voids. Small voids can arrest the damage propagation, but generally do not provide a significant increase in durability because the damage zone deflects around the void and also continues to propagate from other critical regions in the solder ball.

The body is the sensor

An autonomous device called the 'Urchin' is being developed to travel through underground water pipes to listen for leaks. The Urchin consists of a hollow plastic ball just 75 mm in diameter. It must record continuously for the best part of a day. It must not get lost and must 'know' where it is sufficiently accurately to locate the leaks after post-processing data. Pressures can be high, up to 16 Bar (1586 kPa) or more and there must be no water penetration. Therefore, one requirement is to maximise the sensitivity to acoustic leak noise without any penetrations through the skin of the Urchin. At the same time, any other background noise such as that associated with pipe wall interaction must be minimised. This paper will follow our logical path through the possible ways of achieving these requirements and describes the final solution.

Modeling and Simulation of Electronic Packages Subjected to Drop Impact

Board level solder joint reliability performance during drop test is a critical concern to semiconductor and electronic product manufacturers, especially for handheld electronic products. These handheld electronic products are more prone to being dropped during their useful service life because of their small size and light weight. The electronic packages used in portable devices are susceptible to solder joint failures, induced by a combination of printed circuit board (PCB) bending and mechanical shock during impact. The dropping events not only induce mechanical failures in the housing of the device, but also lead to failure of PCB and components mounted on it. This work deals with: (a) Development of a simulation model of complete drop block with printed circuit board and plastic ball grid array (PBGA) assembly, which resembles actual drop test (free fall); (b) Development of an Input-G method for simulating the PCB dynamic responses; and (c) Comparison of results of free fall and Input-G methods. From the simulation results it was found that the mechanical shock causes multiple PCB bending and induce stresses in the solder balls of PBGA package. The solder balls at the outer rows of the PBGA package were subjected to maximum stress. Comparison of free fall drop and Input-G method results revealed that, the Input-G method uses less computer memory, takes less time to solve and it is simple to simulate the drop process.

ZAP: a knowledge-based FEA modeling method for highly coupled variable topology multi-body problems

Some of the most significant challenges in automated CAD–FEA integration are information and model transformations between CAD and FEA tools. These are especially labor-intensive and time-consuming in a newly characterized class of problems termed highly coupled variable topology multi-body (HCVTMB) problems. This paper addresses these challenges with a knowledge-based FEA modeling method called ZAP that consists of three stepping-stone information models and the mapping processes between these models. The information and knowledge of a typical FEA modeling process are explicitly captured in semantically rich information models to achieve benefits including knowledge sharing, system extension, and model modification. ZAP mapping processes automatically transform abstract analytical concepts into tool-specific commands and functions that accomplish HCVTMB model generation and solution management. This method enhances flexibility and reusability in FEA modeling and enables CAD–FEA integration at the knowledge level. To demonstrate the efficacy of ZAP, we overview a sample HCVTMB problem—an electronic chip package plastic ball grid array (PBGA) thermal analysis case study. Experience indicates that ZAP increases knowledge capture and decreases modeling time from days/hours to hours/minutes compared to conventional methods, thus providing a key enabler toward design optimization.

Survival of pneumococcus on hands and fomites

BackgroundPneumococcal hand contamination in Indigenous children in remote communities is common (37%). It is not clear whether this requires frequent inoculation, or if pneumococci will survive on hands for long periods of time. Thus the aim of this study was to determine the survival time of pneumococci on hands and fomites.FindingsThe hands of 3 adult volunteers, a glass plate and plastic ball were inoculated with pneumococci suspended in two different media. Survival at specified time intervals was determined by swabbing and re-culture onto horse blood agar. Pneumococci inoculated onto hands of volunteers were recovered after 3 minutes at 4% to 79% of the initial inoculum. Recovery from one individual was consistently higher. By one hour, only a small number of pneumococci were recovered and this was dependent on the suspension medium used. At subsequent intervals and up to 3 hours after inoculation, < 10 colony forming units were recovered from hands. On a glass plate, pneumococcal numbers dropped an average 70% in the two hours after inoculation. Subsequently, < 100 colony forming units were recovered up to 15 hours after inoculation.ConclusionThe poor survival of pneumococci on hands suggests that the high prevalence of pneumococcal hand contamination in some populations is related to frequent inoculation rather than long survival. It is plausible that hand contamination plays a (brief) role in transmission directly, and indirectly through contamination via fomites. Regular hand washing and timely cleansing or removal of contaminated fomites may aid control of pneumococcal transmission via these routes.

Microstructure evolution based acceleration factor determination for SnAgCu solder joints during thermal cycling

The reliability of lead-free solder used in electronic packages during field-use conditions has traditionally been determined using accelerated thermal cycling (ATC) combined with a Norris-Landzberg type acceleration factor. Limited amount of work exists in quantifying the microstructure evolution of lead-free solder during thermal cycling especially during long-term thermal excursions. A phase coarsening based microstructure evolution has been used in the present work to determine the acceleration factor during thermal cycling. Two different plastic ball grid array (PBGA) packages with different sizes and two different lead-free solder alloys, Sn4.0Ag0.5Cu and Sn3.0Ag0.5Cu, were chosen for the study. The acceleration factor can be determined and hence the package can be qualified for field-use conditions in about the same time duration it takes to perform the ATC test.

2P1-A10 耐衝撃性を考慮した被災地情報収集センサノードの開発(サーチ&amp;レスキューロボット・メカトロニクス)

The paper describes development of prototype of the novel sensor node with impact resistance capability for gathering disaster area information. We have been discussing the development of the gathering information system for disaster area by utilizing rescue robots and wireless sensor networks. Then we propose launching deployment method of the sensor node for deploying dangerous place where a human and robot cannot enter. In order to realize launching deployment, the sensor node has to be protected from dropping impact. Therefore, we covered the sensor node by impact-resistance structure. Prototype of the sensor node consists of plastic ball for the impact-resistance structure and the sensor node core for sensing, communication and information processing. Experiment confirmed that prototype of the sensor node was able to communicate and launch.

Numerical investigation on dynamic characteristics of BGA structural integrity by using finite element method

A specified plastic ball grid array (PBGA) structural integrity prototype which contains different structure and material parameters is designed and manufactured. Based on investigation of the structural and dynamic parameters of PBGA prototype, the numerical simulation of the dynamic characteristics of the PBGA assembly prototype is analysed by using finite element method. The results show that the changing trends of the dynamic modal characteristics during the dynamic excitation. It builds a basis for future work such as the experimental test, structural design and reliability evaluation of PBGA packaging.

Research on parametric analysis for stress of Plastic Ball Grid Array solder joint under shock load

The dynamic response of a Plastic Ball Grid Array (PBGA) assembly under high acceleration load was investigated. Several influencing factors on solder joint stress were studied by using ANSYS. The results indicate that the location of the solder joint is the most important factor and that the outmost solder balls of the PBGA experience maximum stresses. The solder joint height, the modulus of Ball Grid Array (BGA) have little effect on the stress. The peak stress can be reduced effectively by increasing the diameter of the solder joints, reducing the modulus of the solder joint materials.

Combining vibration test with finite element analysis for the fatigue life estimation of PBGA components

The study develops a methodology that combines the vibration failure test, finite element analysis (FEA), and theoretical formulation for the calculation of the electronic component’s fatigue life under vibration loading. A specially designed plastic ball grid array (PBGA) component with built-in daisy chain circuits is mounted on a printed wiring board (PWB) as the test vehicle for the vibration test. It is then excited by a sinusoidal vibration whose frequency equals the fundamental frequency of the test vehicle and tested until the component fails. Because the solder balls are too small for direct measurement of their stresses, FEA is used for obtaining the stresses instead. Thus, the real displacements in the vibration test are then inputted to the FEA model when performing the stress analysis. Consequently, the stress versus failure cycles ( S– N) curve is constructed by correlating both the obtained stresses on the solder balls and the number of failure cycles in the vibration test. Furthermore, the Miner’s rule is applied in calculating the fatigue damage index for those test components when failed. Finally, a formula for the prediction of the component failure cycle is deduced from all these procedures studied. It is also examined later by firstly predicting the fatigue failure cycle of a component and then conducting a vibration test for the same component for the verification purposes. The field test results have proven to be consistent with predicted results. It is then believed that the methodology is effective in predicting component’s life and may be applied further in improving the reliability of electronic systems.

Simultaneous Measurement of PWB and Chip Package Warpage Using Automatic Image Segmentation

The shadow moire and projection moire techniques are widely used methods for measuring printed wiring board (PWB) and PWB assembly (PWBA) warpage. Both methods have high resolution, high accuracy and are suitable for use in an online environment. When measuring the warpage of a bare PWB, maximum warpage across the PWB is calculated by subtracting the minimum out-of-plane displacement on the PWB from the maximum out-of-plane displacement on the PWB. However, when the PWB is populated with electronic components (chip packages); the difference between the maximum and minimum out-of-plane displacements on the PWBA is not the warpage of the PWB or the warpage of the chip packages. In order to use warpage measurement methods such as the shadow and projection moire techniques to accurately and separately determine the warpage of a PWB and chip packages in a PWBA, an automated chip package segmentation algorithm is developed and will be presented in this paper. The automated algorithm is based on active contour models (snakes) and can be used to detect chip package locations on an out-of-plane displacement image of a PWBA. This paper will discuss the characteristics of the automated algorithm, which is applicable to all warpage measurement methods, not just the out-of-plane moire methods. Warpage case studies of PWBs populated with plastic ball grid array chip packages measured using the projection moire technique will also be presented and will show that the developed algorithm along with a warpage measurement method is a powerful tool for measuring the warpage of populated PWBs.

Magnetic Abrasive Finishing Using Nano-size Diamond Dispersed Co-Ni Electroless Plated Plastic Balls and its Application to Post CMP Process

Magnetic Abrasive Particles (MAPs) were successfully prepared by a new technique based on the nickel-cobalt diamond composite plated plastic ball. The finishing results for Damascene samples proved the powerful ability of the new MAPs for application in fabricating electronic devices. In this report, a new process for the preparation of bound MAPs based on the electroless cobalt-nickel boron diamond composite plating on plastic balls is described. Here, plastic balls were used as a support for the growth of MAPs due to its lightweight properties. This work aims to develop lightweight and forceful MAPs. Magnetic field assisted finishing was performed to examine the fabricated MAPs. The AFM images showed the changes in the surface profile before and after finishing by cobalt-nickel diamond composite plated plastic balls for 10 minutes. The AFM images for the sample after MAF suggest that surface smoothing could be attained and that nano-level polishing could be achieved by this method.

Reliability of interfacial adhesion in a multi-level copper/low- k interconnect structure

As the electronics industry continues its efforts in miniaturizing the integrated circuit (IC), an IC chip with copper/low- k stacked back end of line (BEoL) structures has been developed for reducing RC delay in order to obtain high-speed signal communication. However, its reliability might become a concern due to the considerably lower adhesive strength as well as greater coefficient of thermal expansion (CTE) of the low- k materials. In this paper, the four-point bending technique is used to quantify the adhesion energy ( G C). The global local finite element method, including the specified boundary condition (SBC) method and the multi-point constrain (MPC) method, is validated by the four-point bending experiment and is employed as a bridge to estimate the impact from package level to the deep sub-micron BEoL structure of the plastic ball grid array (PBGA) package. A crack driving force of 1.8 J/m 2 acting on the BEoL structure is obtained when the curing process of the moulding compound is performed.

A FEM study on thermal stress of PTHs in a PBGA package

Plastic Ball Grid Array (PBGA) reliability is an issue in terms of thermal deformation. Understanding the thermal deformation process can help determine the cause of PTH (Path Through Hole) cracks via the finite element method. Thermal deformation of a PBGA has been calculated globally with fixed assembly conditions via the FEM while PTH thermal cycle reliability has been estimated locally to show the crack failure mechanism. Finally, Taguchi's method is implemented with 4 factors and 3 levels to uncover the cause of PTH cracks. The calculated FEM results show the weak positions for reliability of a PTH under molding encapsulation boundary, which is found to be much lower than that of other PTHs. This is caused by the maximum von Mises stress of PTH occurring below the comer of the molding encapsulation. Thus, it is strongly recommended that PTH not be located under the molding encapsulation or chip boundaries.

A training model head of plaster of Paris for stereotactic localization

Background A head model for experiencing stereotactic localization will supply familiarity with stereotactic instruments and self confidence for attempters of stereotaxy before real experience. Method Plaster of Paris was molded as a model head in a plastic ball. Then, it was partly chipped at its superior half, and metal pieces were inserted into those chipped surfaces. Later, the stereotactic frame was applied, and axial computed tomographic scanning was obtained. The metal pieces seen on scans were selected as targets, and their coordinates were calculated using the software of the stereotactic equipment. Lastly, the stereotactic needle was introduced with these coordinates for investigation of targeting. Results The model of plaster of Paris head was very suitable for rigid frame fixation. The metal pieces in the model head were clearly observed on computed tomographic scans. The stereotactic biopsy needle introduced with the perviously calculated coordinates was always successful in true targeting. Conclusion This easily performed model head supplied us with familiarity with our stereotactic apparatus and convinced us for further attempts. This kind of model and more complicated ones may help for stereotaxy training in neurosurgery.

Mechanisms behind intrauterine device-induced luteal persistence in mares

Intrauterine glass balls are used to prevent oestrous signs in sports mares, but the mechanism of action is unknown. It has been suggested that the glass ball can mimic an embryo or act via an induced chronic uterine inflammation and absent or continuous low-grade prostaglandin (PG) release. The purpose of this study was to induce prolonged luteal function in mares using a small intrauterine device (IUD) and to study the mechanisms behind prolonged IUD-induced luteal function. A uterine swab and a biopsy specimen were obtained in early oestrus. A water-filled plastic ball, diameter 20 mm and weight 3.6 g, was inserted into the uterus 2–4 days after ovulation; the control mares underwent similar cervical manipulation without ball insertion. The mares were examined three times per week until day 23 and twice weekly thereafter until they returned to oestrus (transrectal palpation, ultrasonography and progesterone determination). The location of the IUD was recorded and ultrasound scans were video-recorded to assess the frequency of uterine contractions. When the mare returned to oestrus, a uterine swab and biopsy specimen were obtained and the bacteriological, cytological and histological (inflammation and glandular dilation) results compared with the samples obtained before the IUD insertion. The PG F 2α metabolite levels were measured in the plasma of four control mares and eight IUD mares on days 11–16. The IUD induced a prolonged luteal phase in 75% of the mares (9/12; IUD-P); the mean dioestrous length was 57.0 days. The three mares that did not respond to the IUD (IUD-N) showed a mean dioestrous length of 15.7 days and the 12 control mares 16.1 days. The inflammation and glandular dilation scores were not significantly different in pre- and post-manipulation biopsy specimens. Although locational changes of the IUD were observed, they occurred over very small distances and were mostly limited within the body-bifurcation area. The IUD-N and control mares showed increased uterine contractility 11–16 days post-ovulation, whereas the IUD-P mares did not. The control mares ( n = 4) and IUD-N mares ( n = 2) showed increased PG levels from day 14 post-ovulation, while the IUD-P mares ( n = 6) showed basal levels only. We concluded that the IUD did not cause continuous PG release and suggest that close contact of the IUD with the endometrium may prevent the endometrial cells from releasing PGF 2α.