Characterization of Wire-Bonding on LDS Materials and HF-PCBs for High-Frequency Applications

Thermosonic wire bonding is a well-established process. However, when working on advanced substrate materials and the associated required metallization processes to realize innovative applications, multiple factors impede the straightforward utilization of the known process. Most prominently, the surface roughness was investigated regarding bond quality in the past. The practical application of wire bonding on difficult-to-bond substrates showed inhomogeneous results regarding this quality characteristic. This study describes investigations on the correlation among the surface roughness, profile peak density and bonding quality of Au wire bonds on thermoplastic and thermoset-based substrates used for high-frequency (HF) applications and other high-end applications. FR4 PCB (printed circuit board flame resitant class 4) were used as references and compared to HF-PCBs based on thermoset substrates with glass fabric and ceramic filler as well as technical thermoplastic materials qualified for laser direct structuring (LDS), namely LCP (liquid crystal polymer), PEEK (polyether ether ketone) and PTFE (polytetrafluoroethylene). These LDS materials for HF applications were metallized using autocatalytic metal deposition to enable three-dimensional structuring, eventually. For that purpose, bond parameters were investigated on the mentioned test substrates and compared with state-of-the-art wire bonding on FR4 substrates as used for HF applications. Due to the challenges of the limited thermal conductivity and softening of such materials under thermal load, the surface temperatures were matched up by thermography and the adaptation of thermal input. Pull tests were carried out to determine the bond quality with regard to surface roughness. Furthermore, strategies to increase reliability by the stitch-on-ball method were successfully applied.

Acute Radial Head Resection for Fracture: are We Likely to Miss an Essex-Lopresti Injury?

Background. Given the current available evidence, surgical treatment of radial head fracture with acute resection is controversial. The aim of this study was to determine whether acute resection of the radial head for a radial head fracture leads to longitudinal forearm instability due to a missed Essex-Lopresti injury. Material and methods. A retrospective review was conducted of radial head resections performed for acute radial head fractures at two Level I trauma centers from 2000 to 2018. A total of 11 patients met inclusion criteria. Our primary outcome was a missed Essex-Lopresti injury at time of final clinical follow-up. Long-term telephone follow-up was attempted for QuickDASH, pain scores, and satisfaction scores. Results. Of the 11 radial head fractures in this study, intraoperative radial pull tests were performed and normal in 6 patients. No patient was found to have a missed Essex-Lopresti injury at a mean of 36.2 months’ clinical follow-up after radial head resection. At a mean telephone follow-up of 12.6 years in available patients, mean QuickDASH was 3.4, mean satisfaction was 9.75 out of 10, and no further complication or reoperation was reported. Conclusion. Our findings challenge the dogma that the radial head cannot be safely excised in the setting of acute fracture, even with elbow instability and/or wrist pain, particularly when intraoperative longitudinal stability is assessed by a stress maneuver.

Record Length Chrome Liner Run Using Innovative, Low-Marking, Non-Ferrous Dies on a Mechanical Casing Running Tool

Abu Dhabi National Oil Company (ADNOC) has steadily advanced toward the use of a casing running tool (CRT) vs. conventional casing running methods to improve efficiency and safety. This advancement focused mainly on 9 ⅝ in to 20 in diameter casing and utilized internal grip tools. Recently they have searched for an external-grip CRT system that would allow them to effectively run the smaller diameter liners of both ferrous and chrome (Cr) materials, especially in the extended reach drilling (ERD) wells with maximum reservoir contact (MRC). For 20 years CRT companies manufactured tools with gripping dies that could efficiently run ferrous material liners. Development of gripping mechanisms which can effectively run corrosion resistant alloy (CRA) materials has been met with varying success. Some of the challenges are to manufacture gripping dies from non-ferrous materials that will not contaminate the CRA liner and develop a gripping pattern that does not mark the CRA liner more than is accepted by API 5CRA industry standards, but maintain effective gripping force. In addition to hoisting and making up the string with no slippage it needs to perform fluid circulation at 3,000 psi. Until recently the liners were typically run in a conventional method using power-tongs. One of the tools chosen for the trial runs was a well-proven, external-grip mechanical CRT designed specifically for smaller diameter casing and liners. It has a 500-ton hoist capacity and a 5,000 psi circulation rating and was packaged with a combination float and cushion tool and a wireless torque turn sub. Dies had been designed to meet the non-contamination and acceptable marking criteria previously mentioned and would be compatible with liners possessing as much as 25% Cr. The dies had been extensively lab-tested, including heavy pull tests and torque application tests, but had not previously been used in field applications. The ERD-MRC well chosen for this trial was planned to have a record length of 6 ⅝ in, 24 ppf, 13% Cr liner with a wedge thread premium connection. In addition to not contaminating the liner, ADNOC expected an average running speed in joints per hour equivalent to the conventional casing running methods and a reduction in time during circulations. The result of the trial was 589 connections (25,035 ft liner length) successfully run with an average running speed matching their expectations. The liner displayed very minimal marks and there were no issues when hoisting or torqueing the connections. In addition, there were no rejected connections during the run. This publication will review the preparation for the run, actual run details, photos of the die marks, torque graphs and conclusions expressed by the operator with recommendations for changes moving forward.

Pull-out and Critical Embedment Length of Grouted Rebar Rock Bolts-Mechanisms When Approaching and Reaching the Ultimate Load

Rock bolts are one of the main measures used to reinforce unstable blocks in a rock mass. The embedment length of fully grouted bolts in the stable and competent rock stratum behind the unstable rock blocks is an important parameter in determining overall bolt length. It is required that the bolt section in the stable stratum must be longer than the critical embedment length to ensure the bolt will not slip when loaded. Several series of pull tests were carried out on fully grouted rebar bolts to evaluate the pull-out mechanics of the bolts. Bolt specimens with different embedment lengths and water/cement ratios were installed in either a concrete block of one cubic meter or in steel cylinders. Load displacement was recorded during testing. For some of the bolts loaded beyond the yield load, permanent plastic steel deformation was also recorded. Based on the test results, three types of failure mechanisms were identified, corresponding to three loading conditions: (1) pull-out below the yield strength of the bolt steel; (2) pull-out between the yield and ultimate loads, that is, during strain hardening of the steel; and (3) steel failure at the ultimate load. For failure mechanisms 2 and 3, it was found that the critical embedment length of the bolt included three components: an elastic deformation length, a plastic deformation length and a completely debonded length due to the formation of a failure cone at the borehole collar.

Towing Tank Model Tests for Propulsive Performance Analysis of a Waterjet-Propelled Amphibious Vehicle

The present study concerns a series of model tests in a towing tank on waterjet propulsive performance. The test model was an armored vehicle consisting of a box-shaped hull, two waterjets, a bow flap, and a trim tab. As per the powering prediction procedure of high-speed vessels, resistance tests, waterjet system tests, and self-propulsion tests were performed. The Froude number based on the characteristic length and advance speed for the model tests ranged from .981 to 1.178. Bollard pull tests were also conducted to investigate the interaction between the hull and two installed waterjets and to validate the flow rate estimation. In the self-propulsion condition, the dry transom and nozzle end modification changed the interaction efficiency. The waterjet reduced the vehicle trim in the self-propulsion condition, owing to the nozzle exit flow onto the trim tab.

Concerted, Computing-Intense Novel MFL Approach Ensuring Reliability and Reducing the Need for Dig Verification

Magnetic Flux Leakage (MFL) is a robust technology with high data coverage. Decades of continuous sizing improvement allowed for industry-accepted sizing reliability. The continuous optimization of sizing processes ensures accurate results in categorizing metal loss features. However, the identified selection of critical anomalies is not always optimal; sometimes anomalies are dug up too early or unnecessarily, this can be caused by the feature type in the field (true metal loss shape) being incorrectly identified which affects sizing and tolerance. In addition, there is the possibility for incorrectly identifying feature types causing false under-calls. Today, complex empirical formulas together with multifaceted lookup tables fed by pull tests, synthetic data, dig verifications, machine learning, artificial intelligence and last but not least human expertise translate MFL signals into metal loss assessments with high levels of success. Nevertheless, two important principal elements are limiting the possible MFL sizing optimization. One is the empirical character of the signal interpretation. The other is the implicitly induced data and result simplification. The reason to go this principal route for many years is simple: it is methodologically impossible to calculate the metal source geometry directly from the signals. In addition, the pure number of possible relevant geometries is so large that simplification is necessary and inevitable. Moreover, the second methodological reason is the ambiguity of the signal, which defines the target of metal loss sizing as the most probable solution. However, even under the best conditions, the most probable one is not necessarily the correct one. This paper describes a novel, fundamentally different approach as a basic alternative to the common MFL-analysis approach described above. A calculation process is presented, which overcomes the empirical nature of traditional approaches by using a result optimization method that relies on intense computing and avoids any simplification. Additionally, the strategy to overcome MFL ambiguity will be shown. Together with the operator, detailed blind-test examples demonstrate the enormous level of detail, repeatability and accuracy of this groundbreaking technological method with the potential to reduce tool tolerance, increase sizing accuracy, increase growth rate accuracy, and help optimize the dig program to target critical features with greater confidence.

Investigations on the execution and evaluation of the Pummel test for polyvinyl butyral based interlayers

Laminated safety glass (LSG) is increasingly used as structural element in buildings. Of central importance for safety are the adhesion and the residual load-bearing capacity in the post fractured state. In literature a large number of tests to assess adhesion is mentioned. These include, e.g. peel tests, through-cracked-tensile/-bending tests, VW-pull tests and compressive shear tests. However, especially in industry, the Pummel test is widespread for determining the quality of adhesion in LSG with polyvinyl butyral based interlayers. This test method proves to be simple and quick to carry out: The laminate is stored at − 18 °C and then completely destroyed at room temperature with hammer blows. The adhesion level (0–10) is determined by visually comparing the adhering glass fragments with reference pictures or with the help of diagrams and tables which indicate the Pummel value as a function of the free film surface. Pummel value 0 is to be interpreted as no adhesion and Pummel value 10 as very high adhesion. Due to the lack of standardization, the execution and evaluation is very much dependent on the test institution and executive person. This paper shows different Pummel classifications that can currently be found on the market. Subsequently, approaches to the automatization and standardization of the execution and especially the evaluation of the Pummel test are shown. Three image evaluation methods in Matlab are presented, discussed and compared: (1) analysis of binary images, (2) statistical evaluation of the greyscale images and (3) texture analysis using co-occurrence matrices.