Technical Library | 2012-06-01 00:08:44.0
Recession survival tips on how and why not to cut training. ... About the methods for US Manufacturing Industry to adjust for the knowledge vacuum caused by retiring baby boomers with training, while dealing with tight training budgets during a recessio
Technical Library | 2016-10-24 15:14:23.0
Biosensors – a new Sensor Type from IST AG What are Biosensors? A biosensor is a device capable of detecting a certain substance or analyte with high specificity. Examples of such analytes are glucose, lactate, glutamine and glutamate. Most biosensors measure the concentration of an analyte in an aqueous solution, usually producing an electrical signal, which is proportional to the analyte’s concentration in its measuring range. An enzymatic biosensor comprises an enzyme, which recognizes and reacts with the target analyte generating a chemical signal, a transducer, which produces a physical signal out of that chemical one, and an electronic amplifier, which conditions and amplifies the signal. Biosensors allow the analysis in complex biological media. The detection of a large number of compounds is of great relevance not only for scientific research but also for process control in the chemical and food industry. It is also indispensable in the health care field for the diagnosis and treatment of diseases and monitoring of illnesses. The pharmaceutical and biotechnology industries greatly desire frequent to continuous analysis of biological media. Such analyses are conducted with the aid of analytical instruments like HPLC systems, which, although robust and reliable, are expensive and have a limited suitability for online operation. For this reason, the acquisition of Jobst Technologies GmbH positions IST AG as a key provider of high-performance and reliable online biosensors.
Technical Library | 2016-07-21 18:16:06.0
Achieving optimum high-frequency printed-circuit-board (PCB) performance is not simply a matter of specifying the best possible PCB material, but can be significantly impacted by PCB fabrication practices. In addition to appropriate circuit materials and circuit design configurations to meet target performance goals, a number of PCB material-related issues can affect final performance, including the use of soldermask, the PCB copper plating thickness, the conductor trapezoidal effect, and plating finish; understanding the effects of these material issues can help when fabricating high-frequency circuits for the best possible electrical performance.
Technical Library | 2016-05-12 16:29:40.0
Advances in miniaturized electronic devices have led to the evolution of microvias in high density interconnect (HDI) circuit boards from single-level to stacked structures that intersect multiple HDI layers. Stacked microvias are usually filled with electroplated copper. Challenges for fabricating reliable microvias include creating strong interface between the base of the microvia and the target pad, and generating no voids in the electrodeposited copper structures. Interface delamination is the most common microvia failure due to inferior quality of electroless copper, while microvia fatigue life can be reduced by over 90% as a result of large voids, according to the authors’ finite element analysis and fatigue life prediction. This paper addresses the influence of voids on reliability of microvias, as well as the interface delamination issue.
Technical Library | 2020-08-27 01:22:45.0
Initially adopted internal specifications for acceptance of printed circuit boards (PCBs) used for wire bonding was that there were no nodules or scratches allowed on the wirebond pads when inspected under 20X magnification. The nodules and scratches were not defined by measurable dimensions and were considered to be unacceptable if there was any sign of a visual blemish on wire-bondable features. Analysis of the yield at a PCB manufacturer monitored monthly for over two years indicated that the target yield could not be achieved, and the main reasons for yield loss were due to nodules and scratches on the wirebonding pads. The PCB manufacturer attempted to eliminate nodules and scratches. First, a light-scrubbing step was added after electroless copper plating to remove any co-deposited fine particles that acted as a seed for nodules at the time of copper plating. Then, the electrolytic copper plating tank was emptied, fully cleaned, and filtered to eliminate the possibility of co-deposited particles in the electroplating process. Both actions greatly reduced the density of the nodules but did not fully eliminate them. Even though there was only one nodule on any wire-bonding pad, the board was still considered a reject. To reduce scratches on wirebonding pads, the PCB manufacturer utilized foam trays after routing the boards so that they did not make direct contact with other boards. This action significantly reduced the scratches on wire-bonding pads, even though some isolated scratches still appeared from time to time, which caused the boards to be rejected. Even with these significant improvements, the target yield remained unachievable. Another approach was then taken to consider if wire bonding could be successfully performed over nodules and scratches and if there was a dimensional threshold where wire bonding could be successful. A gold ball bonding process called either stand-off-stitch bonding (SSB) or ball-stitch-on-ball bonding (BSOB) was used to determine the effects of nodules and scratches on wire bonds. The dimension of nodules, including height, and the size of scratches, including width, were measured before wire bonding. Wire bonding was then performed directly on various sizes of nodules and scratches on the bonding pad, and the evaluation of wire bonds was conducted using wire pull tests before and after reliability testing. Based on the results of the wire-bonding evaluation, the internal specification for nodules and scratches for wirebondable PCBs was modified to allow nodules and scratches with a certain height and a width limitation compared to initially adopted internal specifications of no nodules and no scratches. Such an approach resulted in improved yield at the PCB manufacturer.
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