Technical Library | 2007-08-16 13:34:31.0
While experienced inspectors may be able to determine the aesthetic differences between a lead-free PCB assembly and a tin-lead version, one cannot rely on the "experienced eye". "Less wetting out to the pad edges" (Figure A) and "graininess and lack of shininess of the solder joint" (Figure B) are typical comments about some lead-free solder joints. However, in cases where a Nitrogen atmosphere was present during the reflow of the solder joint (Figure C), there will be little visual differences between the lead free alloys and their tin-lead counterparts.
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 | 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 | 2018-08-23 07:47:57.0
Simply put, the proper system design and use of vacuum in the potting process can make the difference between a mediocre part and a perfect part. Air entrapment is inevitable whether you utilize syringes, cartridges, pails, or drums of material in the process.
Technical Library | 2023-12-18 20:41:20.0
This review of inert atmosphere for the electronics assembly processes will look at the benefits and attempt to close the gap on some of the misconceptions of using inert gases for electronics assembly. We will look at the reasons for using nitrogen and the cost benefits that come with the use of this inert atmosphere gas. As part of this review we will be explain the needs assessment and when you should use an inert atmosphere for your assembly process. Case studies will be provided to demonstrate the benefits of an inert atmosphere in the electronics assembly process area.
Technical Library | 2011-12-15 17:21:42.0
manganese dioxide or conductive polymer cathode. Higher stability is achieved by placement of the capacitor into an SMD case filled by an inert atmosphere and hermetically sealed. The long term stability testing performed on such hermetically sealed capac
Technical Library | 2018-06-04 13:52:05.0
Potting in a vacuum or atmospheric conditions? This question about the correct procedure concerns many users, among others i.e. electronics manufacturers, who pot more and more complex parts and components for a huge variety of products. Against the actual requirements of product and process, a decision on the procedure is often made under the assumption: „Potting under atmosphere = affordable and easy" and „Potting under vacuum = expensive and difficult". But that's a thing of the past. The way to the correct method, however, requires the clarification of a number of factors.
Technical Library | 2013-10-24 15:47:53.0
Reflow soldering in a nitrogen atmosphere is a common process consideration in surface mount technology assembly. This is because the use of nitrogen in reflow equipment may benefit the process as well as the quality of the end product, where it can increase the reliability of the solder joint. (...) The present study investigated thoroughly the effect of different reflow soldering atmosphere, which is air and nitrogen on IMC formation and growth
Technical Library | 2007-11-08 17:35:46.0
A continuous furnace is ideal for processes requiring high production volumes, process consistency, and precision control. This overview discusses some of the newer temperature and atmosphere capabilities of continuous furnaces and addresses the various components that make up a continuous furnace.
Technical Library | 2017-07-06 15:50:17.0
Head-in-pillow (HiP) is a BGA defect which happens when solder balls and paste can't contact well during reflow soldering. Package warpage was one of the major reasons for HiP formation. In this paper, package warpage was measured and simulated. It was found that the package warpage was sensitive to the thickness of inside chips. A FEM method considering viscoelastic property of mold compound was introduced to simulate package warpage. The CTE mismatch was found contributes to more than 90% of the package warpage value when reflowing at the peak temperature. A method was introduced to measure the warpage threshold, which is the smallest warpage value that may lead to HiP. The results in different atmospheres showed that the warpage threshold was 50μm larger in N2 than that in air, suggesting that under N2 atmosphere the process window for HiP defects was larger than that under air, which agreed with the experiments.
