Technical Library | 2015-02-27 17:06:01.0
The drive towards fine pitch technology also affects the soldering processes. Selective soldering is a reliable soldering process for THT (through hole) connectors and offers a wide process window for designers. THT connectors can be soldered on the top and bottom side of boards, board in board, PCBs to metal shields or housing out of plastic or aluminum are today's state of the art. The materials that are used to make the solder connections require higher temperatures. Due to the introduction of lead-free alloys, the boards need more heat to get the barrels filled with solder. This not only affects the properties of the flux and components, but the operation temperatures of solder machines become higher (...)First the impact of temperature will be discussed for the separate process steps and for machine tooling. In the experimental part measurements are done to verify the accuracy that can be achieved using today's selective soldering machines. Dedicated tooling is designed to achieve special requirements with respect to component position accuracy.
Technical Library | 2023-11-14 19:24:08.0
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.
Technical Library | 2016-10-27 16:24:23.0
Press-fit technology is a proven and widely used and accepted interconnection method for joining electronics assemblies. Printed Circuit Board Assembly Systems and typical functional subassemblies are connected through press-fit connectors. The Press-Fit Compliant Pin is a proven interconnect termination to reliably provide electrical and mechanical connections from a Printed Circuit Board to an Electrical Connector. Electrical Connectors are then interconnected together providing board to board electrical and mechanical inter-connection. Press-Fit Compliant Pins are housed within Connectors and used on Backplanes, Mid-planes and Daughter Card Printed Circuit Board Assemblies. High reliability OEM (Original Equipment Manufacturer) computer designs continue to use press-fit connections to overcome challenges associated with soldering, rework, thermal cycles, installation and repair. This paper investigates the technical roadmap for press fit technology, putting special attention to main characteristics such, placement and insertion, inspection, repair, pin design trends, challenges and solutions. Critical process control parameters within an assembly manufacturing are highlighted.
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 | 2008-12-11 01:15:56.0
Flame retardants have been around since the Egyptians and Romans used alum to reduce the flammability of wood. Brominated flame retardants (BFRs) first experienced use after World War II as the substitution of wood and metal for plastics and foams resulted in materials that were much more flammable. The widespread use of BFRs initiated in the 1970s with the explosion of electronics and electrical equipment and housings. For the US market, all of these products must conform to the UL 94 flammability testing specifications. In fact, the most common printed circuit board (PCB) in the electronics industry, FR-4, is defined by its structure (glass fiber in an epoxy matrix) and its compliance to UL 94 V0 standard.
Technical Library | 2017-01-19 16:58:47.0
The biggest problem with designing rigid-flex hybrid PCBs is making sure everything will fold in the right way, while maintaining good flex-circuit stability and lifespan. The next big problem to solve is the conveyance of the design to a fabricator who will clearly understand the design intent and therefore produce exactly what the designer/engineer intended.Rigid-Flex circuit boards require additional cutting and lamination stages, and more exotic materials in manufacturing and therefore the cost of re-spins and failures are very much higher than traditional rigid boards. To reduce the risk and costs associated with rigid-flex design and prototyping, it is desirable to model the flexible parts of the circuit in 3D CAD to ensure correct form and fit. In addition it is necessary to provide absolutely clear documentation for manufacturing to the fabrication and assembly houses.
Technical Library | 2019-10-18 10:37:25.0
It usually does not make any logic to invest in costly fabrication equipment in case you just desire to spin some prototypes and rather outsource your Printed Circuit Board assembly as well as prototype fabrication to a trustworthy vendor. I would provide a few tips as to what to consider when seeking a contract manufacturer. The two most common procedures associated with Printed Circuit Board Assembly are through-hole technology and surface mount technology. Talking about the difference between through-hole technology and surface mount technology. Through-hole elements have metal leads, & these metal leads are supplied through-plated holes inside the circuit board. On the other hand, SMT elements might or might not have leads, nevertheless most significantly, they are developed to be soldered onto the surface of the circuit boards straight on the same side as the element body. A lot of contract manufacturers would provide a quick quote mechanism over their site for the fabrication of circuit boards as well as assembly of prototypes. This would bank your time when comparing various vendors. Ensure that the quote system facilitates you to fill your details, for instance, board material, thickness, copper thickness, milling, etc. in order that you can avail of a precise quote devoid of any surprises afterward. And this is quite necessary. Typically the cost per board would decline as quality upgrades. This is owing to the fairly high setup price of circuit board fabrication over and above component assembly. A few vendors would employ a system where they unite boards from various consumers. This manner the setup price would be circulated among numerous clients. When you fabricate an item, you clearly don’t desire to have to fabricate a big quantity of boards straight away whilst you improve your design. One restriction with small quantity prototypes though is that the option of materials & material thicknesses would be constrained. In case you are employing a particular material then opportunities are there will not be any other clients employing the same material. Additionally, lead time plays a major role in indecisive prices. A longer lead time facilitates the fabricator more liberty in slotting your fabrication. This is basically reflected in cheaper prices that would view in the quote section. Clearly, if you are in a hurry and desire to be moved to the summit of the pile you would require splurging more dollars. Ensure that your contract fabricator would support the file sort for producing which you offer. The most general format for printed circuit board fabrication is the Gerber format nonetheless a few vendors would moreover embrace board files from general printed circuit board software products. A few suppliers also provide in house printed circuit design. Even in case, you create your board yourself, choosing a vendor with design services might prove resourceful in case there is an issue with your files. In this scenario, your vendor could make swift changes that would neglect pricey delays. If you are looking for an Electronic Manufacturing Services (EMS Assembly) provider, then the web is the best to search.
Technical Library | 2020-08-19 19:13:00.0
Commercially available health monitors rely on rigid electronic housing coupled with aggressive adhesives and conductive gels, causing discomfort and inducing skin damage. Also, research-level skin-wearable devices, while excelling in some aspects, fall short as concept-only presentations due to the fundamental challenges of active wireless communication and integration as a single device platform. Here, an all-in-one, wireless, stretchable hybrid electronics with key capabilities for real-time physiological monitoring, automatic detection of signal abnormality via deep-learning, and a long-range wireless connectivity (up to 15 m) is introduced. The strategic integration of thin-film electronic layers with hyperelastic elastomers allows the overall device to adhere and deform naturally with the human body while maintaining the functionalities of the on-board electronics. The stretchable electrodes with optimized structures for intimate skin contact are capable of generating clinical-grade electrocardiograms and accurate analysis of heart and respiratory rates while the motion sensor assesses physical activities. Implementation of convolutional neural networks for real-time physiological classifications demonstrates the feasibility of multifaceted analysis with a high clinical relevance. Finally, in vivo demonstrations with animals and human subjects in various scenarios reveal the versatility of the device as both a health monitor and a viable research tool.
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