Technical Library | 2022-10-11 20:29:31.0
Electronic assemblies deployed in harsh environments may be subjected to multiple thermal environments during the use-life of the equipment. Often the equipment may not have any macro-indicators of damage such as cracks or delamination. Quantiication of thermal environments during use-life is often not feasible because of the data-capture and storage requirements, and the overhead on core-system functionality. There is need for tools and techniques to quantify damage in deployed systems in absence of macro-indicators of damage without knowledge of prior stress history. The presented PHM framework is targeted towards high reliability applications such as avionic and space systems. In this paper, Sn3.0Ag0.5Cu alloy packages have been subjected to multiple thermal cycling environments including -55 to 125C and 0 to 100C. Assemblies investigated include area-array packages soldered on FR4 printed circuit cards. The methodology involves the use of condition monitoring devices, for gathering data on damage pre-cursors at periodic intervals. Damage-state interrogation technique has been developed based on the Levenberg-Marquardt Algorithm in conjunction with the microstructural damage evolution proxies. The presented technique is applicable to electronic assemblies which have been deployed on one thermal environment, then withdrawn from service and targeted for redeployment in a different thermal environment. Test cases have been presented to demonstrate the viability of the technique for assessment of prior damage, operational readiness and residual life for assemblies exposed to multiple thermo-mechanical environments. Prognosticated prior damage and the residual life show good correlation with experimental data, demonstrating the validity of the presented technique for multiple thermo-mechanical environments.
Technical Library | 2021-09-29 13:35:21.0
In PCB circuit assemblies the trend is moving to more SMD components with finer pitch connections. The majority of the assemblies still have a small amount of through hole (THT) components. Some of them can't withstand high reflow temperatures, while others are there because of their mechanical robustness. In automotive applications these THT components are also present. Many products for cars, including steering units, radio and navigation, and air compressors also use THT technology to connect board-to-board, PCB's to metal shields or housings out of plastic or even aluminium. This is not a simple 2D plain soldering technology, as it requires handling, efficient thermal heating and handling of heavy (up to 10 kg) parts. Soldering technology becomes more 3D where connections have to be made on different levels. For this technology robots using solder wire fail because of the spattering of the flux in the wires and the long cycle time. In wave soldering using pallets the wave height is limited and pin in paste reflow is only a 2D application with space limitations. Selective soldering using dedicated plates with nozzles on the solder area is the preferred way to make these connections. All joints can be soldered in one dip resulting in short cycle times. Additional soldering on a small select nozzle can make the system even more flexible. The soldering can only be successful when there is enough thermal heat in the assembly before the solder touches the board. A forced convection preheat is a must for many applications to bring enough heat into the metal and board materials. The challenge in a dip soldering process is to get a sufficient hole fill without bridging and minimize the number of solder balls. A new cover was designed to improve the nitrogen environment. Reducing oxygen levels benefits the wetting, but increases the risk for solder balling. Previous investigations showed that solder balling can be minimized by selecting proper materials for solder resist and flux.
Technical Library | 2020-05-28 02:19:28.0
Properly functioning printed circuit boards are essential for both manufacturers of electronic devices and also the developers if the overall intent is for the electronic device to function at high capacity. From designing the schematics of the printed circuit boards to testing the products, there is no process of PCB manufacturing and/or assembly that can be taken for granted. While it's true that you can attempt this process on your own, especially if you are in possession of a large scale manufacturing facility, here are a few reasons why it would be a better option to opt for a professional company for PCB manufacturing and assembly. 1. Variety A professional printed circuit boards manufacturing company will be able to offer you a huge variety. You will be able to choose from rigid, flexible, or rigid-flex. What's more, the PCBs will be customized as per the need of the application. 2. Quality Professional and good printed circuit board manufacturing and assembling companies might cost you just a little bit extra but they also guarantee to produce the best results and offer very high quality products. In the end, it is quality that will make the difference between mediocre and a high functioning PCB. 3. Cost Efficiency Since you don't have to waste time or resources on buying equipment to produce the best PCBs or hiring staff to oversee the process, you can actually end up saving money. You can even save on PCB assembly cost by hiring this job out. All you have to do is to negotiate the quote and sit back, relax, and wait for the PCBs to be delivered to you. 4. Eliminate Design Flaws Design engineers hired by PCB manufacturing and assembling companies use the best graphic software to develop and test the schematics of PCBs. This increases the chances of eliminating flaws in the printed circuit boards during the initial design phase. 5. Multilayer PCB Manufacturing and Assembly The process of manufacturing and assembling multilayer PCBs is as intricate as it sounds. All processes of manufacturing and assembling multilayer PCBs require the best machines and trained technicians to pass the quality and functionality tests. Manufacturing and assembling multilayer printed circuit boards yourself is going to cost you a lot. Even the smallest of mistakes during the manufacturing and assembling process might render the entire PCB entirely useless. 6. Save Time PCBs are just a single part of the electronic device. To complete the device, many more pieces would be needed. The manufacturers of the electronic device can hire out the job of manufacturing or assembling the PCBs, which will mean they will have one less chore to do. This, in turn, will save you a lot of time which could be spent on elevating the quality of the product. 7. Experience Experience makes all the difference. It is what makes the name of any company reliable in the market. Long experience of manufacturing and assembling printed circuit boards makes the company well versed in the process and it also makes it an expert to identify design, manufacturing, assembling, and testing needs of certain applications We, at Asia Pacific Circuits, offer these benefits and so much more. For quick turn PCB assembly, PCB manufacturing and PCB designing, you can contact us anytime.
