Technical Library | 2023-01-17 17:19:44.0
A test program was developed to evaluate the effectiveness of vacuum reflow processing on solder joint voiding and subsequent thermal cycling performance. Area array package test vehicles were assembled using conventional reflow processing and a solder paste that generated substantial void content in the solder joints. Half of the population of test vehicles then were re-processed (reflowed) using vacuum reflow. Transmission x-ray inspection showed a significant reduction in solder voiding after vacuum processing. The solder attachment reliability of the conventional and vacuum reflowed test vehicles was characterized and compared using two different accelerated thermal cycling profiles. The thermal cycling results are discussed in terms of the general impact of voiding on solder thermal fatigue reliability, results from the open literature, and the evolving industry standards for solder voiding. Recommendations are made for further work based on other void reduction methods and additional reliability studies.
Technical Library | 2023-01-17 17:27:13.0
Reflow profile has significant impact on solder joint performance because it influences wetting and microstructure of the solder joint. The degree of wetting, the microstructure (in particular the intermetallic layer), and the inherent strength of the solder all factor into the reliability of the solder joint. This paper presents experimental results on the effect of reflow profile on both 63%Sn 37%Pb (SnPb) and 96.5%Sn 3.0%Ag 0.5%Cu (SAC 305) solder joint shear force. Specifically, the effect of the reflow peak temperature and time above solder liquidus temperature are studied. Nine reflow profiles for SAC 305 and nine reflow profiles for SnPb have been developed with three levels of peak temperature (230 o C, 240 o C, and 250 o C for SAC 305; and 195 o C, 205 o C, and 215 o C for SnPb) and three levels of time above solder liquidus temperature (30 sec., 60 sec., and 90 sec.). The shear force data of four different sizes of chip resistors (1206, 0805, 0603, and 0402) are compared across the different profiles. The shear force of the resistors is measured at time 0 (right after assembly). The fracture surfaces have been studied using a scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS)
Technical Library | 2024-08-29 18:30:46.0
The mechanical experience of consumption (i.e., feel, softness, and texture) of many foods is intrinsic to their enjoyable consumption, one example being the habit of twisting a sandwich cookie to reveal the cream. Scientifically, sandwich cookies present a paradigmatic model of parallel plate rheometry in which a fluid sample, the cream, is held between two parallel plates, the wafers. When the wafers are counterrotated, the cream deforms, flows, and ultimately fractures, leading to separation of the cookie into two pieces. We introduce Oreology (/Oriːˈɒl@dʒi/), from the Nabisco Oreo for "cookie" and the Greek rheo logia for "flow study," as the study of the flow and fracture of sandwich cookies. Using a laboratory rheometer, we measure failure mechanics of the eponymous Oreo's "creme" and probe the influence of rotation rate, amount of creme, and flavor on the stress–strain curve and postmortem creme distribution. The results typically show adhesive failure, in which nearly all (95%) creme remains on one wafer after failure, and we ascribe this to the production process, as we confirm that the creme-heavy side is uniformly oriented within most of the boxes of Oreos. However, cookies in boxes stored under potentially adverse conditions (higher temperature and humidity) show cohesive failure resulting in the creme dividing between wafer halves after failure. Failure mechanics further classify the creme texture as "mushy." Finally, we introduce and validate the design of an open-source, three-dimensionally printed Oreometer powered by rubber bands and coins for encouraging higher precision home studies to contribute new discoveries to this incipient field of study
Technical Library | 2023-11-09 08:53:45.0
Crafting an Efficient SMT Conformal Coating Line for Double-Sided PCBA In the intricate realm of electronics manufacturing, selecting the ideal SMT conformal coating line can seem like a challenging quest. The pursuit of a solution that seamlessly integrates efficiency, reliability, and performance is the ultimate goal. In this article, we embark on a journey to unravel the secrets of a standard SMT conformal coating line, using a captivating visual guide as our compass. The Symphony Of Components In An SMT Conformal Coating Line Picture a finely orchestrated symphony, with each instrument playing a unique role in this PCB coating process. The star performers in this lineup include: Transfer Conveyor: These act as the stage where the PCB's journey begins. Think of them as the entry and exit points for your precious boards, allowing a smooth, choreographed dance through the line. 1st Coating Machine: As the first movement in this musical journey, this machine, partnered with the initial curing station, lays down the foundation – applying adhesive to one side of the PCB. Inspection Conveyor: After the initial curing, our inspectors take center stage, using these transfer stations to carefully evaluate the coating's quality. 1st Curing Oven: This is where the magic happens. The first curing oven solidifies the adhesive applied in the previous act, setting the tone for a flawless performance. Flipper Machine: The flipper machine takes the spotlight, gracefully turning the PCB to reveal its other side, ensuring both faces receive their share of adhesion. 2nd Coating Machine: With a newfound perspective, the second coating machine takes the stage, applying adhesive to the reverse side of the PCB. 2nd Curing Oven: The grand finale! The second curing oven brings our symphony to a breathtaking close, solidifying the adhesive applied in the second act, creating a harmonious, dual-sided masterpiece. Efficiency Meets Dual-Side Coating This SMT conformal coating line is like a well-choreographed ballet that requires at least two dancers. One stands at the front, carefully loading PCBs onto the stage, guiding them through the first act. After the flip, the second dancer carries them through the second act, with both sides perfectly coated, ensuring a flawless performance for applications requiring dual-sided adhesion. UV Curing Oven For Illuminating Results For applications that embrace UV-curable adhesives, our line includes UV curing ovens, adding a layer of brilliance to the process and ensuring an efficient solidification of adhesives. Transfer Stations With A Touch Of Magic Within this symphony, the transfer stations wear a touch of magic – the second and fourth stations feature enchanting blue glass covers illuminated by embedded LED lights. These stations offer operators a clear view of the adhesive quality, allowing for meticulous inspections. The blue glass covers also act as protective shields, guarding freshly coated PCBs from the ever-present dust fairies. Certified Excellence: European Standards And CE Certification Ensuring that our performance meets the highest standards, our entire ensemble adheres to stringent European safety standards and proudly boasts CE certification, a testament to compliance with safety, health, and environmental protection requirements. A Variety Of Coating Machines For Your Unique Needs Our lineup doesn't just feature one star, but an ensemble of coating machines, including models like I.C.T-T550, I.C.T-T550U, I.C.T-T600, and I.C.T-T650. For an encore performance with detailed specifications of each model, please refer to our dedicated article. Additionally, for a captivating exploration of the right coating valve for your adhesive, please visit our comprehensive guide. Single-Sided PCB Coating For those who prefer a single board, our dedicated article on single-sided PCB coating is a spotlight on this specialized process. In the dynamic world of electronics manufacturing, our SMT conformal coating line stands as a versatile and reliable performance. With dual-sided coating capabilities, adherence to European safety standards, and CE certification, we offer a comprehensive platform for your coating needs. Join us in this symphony and explore our range of coating machines and accessories to enhance your conformal coating process. It's a performance that promises to leave you in awe!
Technical Library | 2012-10-04 18:52:43.0
First published in the 2012 IPC APEX EXPO technical conference proceedings... Due to the obsolescence of SnPb BGA components, electronics manufacturers that use SnPb solder paste either have to use lead-free BGAs and adjust the reflow process or re-ball t
Technical Library | 2018-10-20 13:50:05.0
With this easy-to-use Troubleshooting Guide, you can learn to troubleshoot common SMT issues. After using it a few times, it will become an essential companion for you and anyone in your company responsible for operating an SMT line. This Guide offers troubleshooting advice for common SMT assembly issues by process defect. If your issue is not resolved after following the steps to help identify the possible root cause and solution, please contact your Cookson Electronics representative who will be able to provide you with further assistance.
Technical Library | 1999-05-07 10:14:57.0
This paper describes a model developed to calculate number of redundant good die per wafer. A block redundancy scheme is used here, where the entire defective memory subarray is replaced by a redundant element. A formula is derived to calculate the amount of improvement expected after redundancy. This improvement is given in terms of the ratio of the overall good die per wafer to the original good die per wafer after considering some key factors.
Technical Library | 2012-12-26 20:18:50.0
①Single side The basic flexible printed circuit board is used of substrate of single side pcb materials and coated coverlay after finishing printed. ②Double sided That is made of substrates of double sided printed circuit board with double surface coated coverlays after finishing printed. ③Single copper foil with double coverlays Single copper foil coated different coverlays with double surface after finishing printed. ④Air gap Laminating two single printed circuit board together with no glue and bare design to meet high flexibility requirements. ⑤Multilayer That is designed for three and above circuit layers by laminating single side printed circuit board or double sided printed circuit board. ⑥COF IC chips and electronic components are installed on the flexible circuit board directly. ⑦Rigid-Flexible PCB Combined to rigid PCB with supporting and flexible PCB with high flexibility.
Technical Library | 2008-03-18 12:36:31.0
This paper examines the construction of a notebook mainboard with more than 2000 components and no wave soldering required. The board contains standard SMD, chipset BGAs, connectors, through hole components and odd forms placed using full automation and soldered after two reflow cycles under critical process parameters. However, state of the art technology does not help if the process parameters are not set carefully. Can all complex BGAs, THTs and even screws be soldered on a single stencil? What will help us overcome bridging, insufficient solder and thombstoning issues? This paper will demonstrate the placement of all odd shape components using pin-in-paste stencil design and full completion of the motherboard after two reflow cycles.
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.
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