Nexlogic Technologies Inc.

United States

Nexlogic Technologies Inc.

United States
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Khan Z.,NexLogic Technologies Inc.
SMT Surface Mount Technology Magazine | Year: 2013

Shrinking PCB real estate, ultrafine-pitch devices, package-on-package technologies, thinner boards, and the recent adoption of challenging device packaging give the use of first article inspection greater importance.


Khan Z.,Nexlogic Technologies Inc.
SMT Surface Mount Technology Magazine | Year: 2013

Zulki Khan informs that automated optical inspection (AOI) and X-rays are being increasingly used to detect a variety of board assembly problems in PCB designs. AOI takes on a variety of key assignments, such as checking out the numbers labeled on passive and active devices and matching them with the database to assure that they are legitimate components as specified in the BOM. The AOI machine is trained to verify alternate parts regardless of manufacturer, till the device has the same footprint, value, tolerance, voltage, and package type. AOI is also excellent at detecting missing or wrong components and misalignments. X-ray can be used along with AOI and help in detecting a marginal connection between a component lead and the PCB's surface. AOI is also effective in catching problems associated with passive devices, such as capacitors, resistors, and inductors, along with problems related to active devices with leads extending from the package.


Khan Z.,Nexlogic Technologies Inc.
SMT Surface Mount Technology Magazine | Year: 2012

It's a good idea to ratchet up specifications to assure higher reliability. An EMS provider can increase board specs beyond an OEM's minimum engineering specifications so that the board and its end-product maintain high performance and optimum reliability-regardless of environmental, terrain, or temperature conditions.


Khan Z.,NexLogic Technologies Inc.
SMT Surface Mount Technology Magazine | Year: 2014

PCB cleanliness on the assembly floor is now getting more attention, due to tiny residues and contaminants being left on assemblies after new, advanced assembly processes. If a small amount of flux remains trapped under the board's surface, it can change the characteristics of impedance, resistivity. This could also change what could have been a perfect eye diagram, and in general, change the optimal level of operation. Ultra cleanliness is even more critical if underfill. Most assemblies are cleaned using de-ionized or DI water. DI water is generally heated to a temperature in the range of 100-120°F. It usually contains 3-5% chemistry, and the rest is water. Most contaminants are cleaned using de-ionized water. When it comes to special agents that cannot be cleaned at a specific temperature, in some cases, cleaning agents need to be changed. This involves changing the concentration of the cleaning agent, the wash cycle temperature, and the speed of the rinse cycle to achieve better results.


Khan Z.,NexLogic Technologies Inc.
SMT Surface Mount Technology Magazine | Year: 2014

Products and their supporting PCBs and packages have shrunk so much that it is considerably challenging to detect extremely small problems. But a forensic approach can help uncover defects that traditional methods may miss.


Khan Z.,NexLogic Technologies Inc.
SMT Surface Mount Technology Magazine | Year: 2013

There is thermal compression, ultrasonic wedge, and a combination of the two, called thermal sonic. Each has different characteristics, which pose various issues and concerns that can have adverse effects on the overall reliability of the final board. So the CM or EMS provider has to decide on the wiring technology best suited to a given board application. Determination must be made on wire thickness, chemical composition, diameter, and along with diameter, determination must be made as to the frequency for bonding purposes and power. Regardless of the type of wiring used, each has its pros and cons. One type might be better for attaching a flip chip to a PCB. But chipon-board attach might prove more robust and more effective using yet another wiring version. In some cases, aluminum wires are better; other times, gold wire is more suitable, or ribbon wire or die bonding for a given PCB application depending on different temperature ranges and other variables.


Khan Z.,Nexlogic Technologies Inc
SMT Surface Mount Technology Magazine | Year: 2014

A high-speed PCB is subjected to all the key test and verification steps at assembly and test. High-speed boards might pass at certain lower spectrum speeds, but begin failing at certain other higher speeds. The high-speed board may be perfect when it comes to BGA assembly. All the balls properly collapse; all the thermal profiles are accurately determined and performed. In the course of the investigation, it must be determined whether or not the material used is straight FR-4, a hybrid, Rogers or polyimide and how it may be affecting the board fabrication process. Certain questions dealing with ICs and other components on that questionable board also need to be asked and carefully probed. If they are running a very tight tolerance, changing even the core of the pre-preg or the laminate is going to adversely affect the impedance calculations. At the top of the list is contacting the company that designed and manufactured that particular FPGA that is causing issues on the board.


Khan Z.,Nexlogic Technologies Inc.
Assembly | Year: 2010

The effective design for Assembly (DfM) takes into account the practice and implementation of placing checks and balances at the right places during the three major stages-design, fabrication, and assembly and test. Correctly splitting a PCB's circuitry is another key aspect of DfM. The PCB designer must clearly understand that high-frequency, high-noise generating devices such as analog, which must be kept sufficiently away from noise-sensitive digital ones, especially digital clocks. A simple PCB with enough real estate to avoid affecting circuitry performance can have power and ground signals on the top and bottom side without the need to create other power and ground planes. Component placement is another critical aspect and has a significant role in PCB layout and design. Correctly placing components reduces the number of layers on the fabrication side of the board. A PCB designer must correctly calculate impedance control properly so that all transmit and return signals are intact.


Khan Z.,NexLogic Technologies Inc.
SMT Surface Mount Technology Magazine | Year: 2013

Sumary: RF design in the past was nearly an impossible task for engineers\-the know-how and technology were simply nonexistent. Now, with demand for such design growing at an incredible pace and the technology needed readily available, the PCB designer and assembly engineer should fully understand how to deal with RF intricacies.


Khan Z.,NexLogic Technologies Inc.
SMT Surface Mount Technology Magazine | Year: 2013

Engineering change orders (ECOs) have been part of the product development and PCB field from the beginning, as they play a key role in the accuracy of design. ECOs are generated during the engineering debugging and bring-up phase of the board when issues are found. These ECOs can be applied to the rest of the same first lot. ECOs can also be written and implemented on the remaining 15 boards. These ECOs can be implemented on those complete sets of boards to make them work without having to re-spin these designs if all of them have been assembled. The ECO will be unable to have any effect on the accuracy of a design until the first set of boards has been designed, manufactured, and assembled. The highly experienced and modern PCB designer always takes a strategic approach to avoid or minimize ECOs in PCB designs.

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