Technical Library | 2023-05-02 18:50:24.0
Surface-mount PCB components are smaller than their lead-based counterparts and provide a radically higher component density. They are available in a variety of shapes and sizes designated by a series of standardized codes curated by the electronics industry. Of these PCB components, the 0201-sized are the smallest, measuring 0.024 x 0.012 in. (0.6 x 0.3 mm) – that's 70% smaller than the previous 0402 level! The 0201 components are designed to improve reliability in space-constrained applications such as portable electronics like smartphones, tablets, robotics and digital cameras, but require delicate handling during the assembly process. Given the miniaturized dimensions of an 0201 package, it is crucial that the mounting process abide by a series of guidelines regarding the design of the PCB mounting pads and solderable metallization, PCB circuit trace width, solder paste selection, package placement and overages, solder paste reflow, solder stencil screening, and final inspection. It's advisable that one review this information when procuring the services of a PCB assembler.
Technical Library | 2014-08-19 15:39:13.0
Understanding warpage of package attach locations on PCBs under reflow temperature conditions is critical in surface mount technology. A new industry standard, IPC 9641, addresses this topic directly for the first time as an international standard.This paper begins by summarizing the sections of the IPC 9641 standard, including, measurement equipment selection, test setup and methodology, and accuracy verification. The paper goes further to discuss practical implementation of the IPC 9641 standards. Key advantages and disadvantages between available warpage measurement methods are highlighted. Choosing the correct measurement technique depends on requirements for warpage resolution, data density, measurement volume, and data correlation. From industry experience, best practice recommendations are made on warpage management of PCB land areas, covering how to setup, run, analyze, and report on local area PCB warpage.The release of IPC 9641 shows that flatness over temperature of the package land area on the PCB is critical to the SMT industry. Furthermore, compatibility of shapes between attaching surfaces in SMT, like a package and PCB, will be critical to product yield and quality in years to come.
Technical Library | 2015-05-28 17:34:48.0
The printed circuit board assembly industry has long embraced the "Smaller, Lighter, Faster" mantra for electronic devices, especially in our ubiquitous mobile devices. As manufacturers increase smart phone functionality and capability, designers must adopt smaller components to facilitate high-density packaging. Measuring over 40% smaller than today's 0402M (0.4mmx0.2mm) microchip, the new 03015M (0.3mm×0.15mm) microchip epitomizes the bleeding-edge of surface mount component miniaturization. This presentation will explore board and component trends, and then delve into three critical areas for successful 03015M adoption: placement equipment, assembly materials, and process controls. Beyond machine requirements, the importance of taping specifications, component shape, solder fillet, spacing gap, and stencil design are explored. We will also examine how Adaptive Process Control can increase production yields and reduce defects by placing components to solder position rather than pad. Understanding the process considerations for 03015M component mounting today will help designers and manufacturers transition to successful placement tomorrow.
Technical Library | 2020-03-26 14:55:29.0
This paper introduces line confocal technology that was recently developed to characterize 3D features of various surface and material types at sub-micron resolution. It enables automatic microtopographic 3D imaging of challenging objects that are difficult or impossible to scan with traditional methods, such as machine vision or laser triangulation.Examples of well-suited applications for line confocal technology include glossy, mirror-like, transparent and multi-layered surfaces made of metals (connector pins, conductor traces, solder bumps etc.), polymers (adhesives, enclosures, coatings, etc.), ceramics (components, substrates, etc.) and glass (display panels, etc.). Line confocal sensors operate at high speed and can be used to scan fast-moving surfaces in real-time as well as stationary product samples in the laboratory. The operational principle of the line confocal method and its strengths and limitations are discussed.Three metrology applications for the technology in electronics product manufacturing are examined: 1. 3D imaging of etched PCBs for micro-etched copper surface roughness and cross-sectional profile and width of etched traces/pads. 2. Thickness, width and surface roughness measurement of conductive ink features and substrates in printed electronics applications. 3. 3D imaging of adhesive dots and lines for shape, dimensions and volume in PCB and product assembly applications.
Technical Library | 2020-10-08 01:01:01.0
Flexible hybrid electronics (FHE) is emerging as a promising solution to combine the benefits of printed electronics and silicon technology. FHE has many high-impact potential areas, such as wearable applications, health monitoring, and soft robotics, due to its physical advantages, which include light weight, low cost and the ability conform to different shapes. However, physical deformations in the field can lead to significant testing and validation challenges. For example, designers must ensure that FHE devices continue to meet their specs even when the components experience stress due to bending. Hence, physical deformation, which is hard to emulate, has to be part of the test procedures for FHE devices. This paper is the first to analyze stress experience at different parts of FHE devices under different bending conditions. We develop a novel methodology to maximize the test coverage with minimum number of text vectors with the help of a mixed integer linear programming formulation. We validate the proposed approach using an FHE prototype and COMSOL Multiphysics simulations
Technical Library | 2021-06-15 18:40:53.0
The jet printing of a dense mixed non-Newtonian suspension is based on the rapid displacement of fluid through a nozzle, the forming of a droplet and eventually the break-off of the filament. The ability to model this process would facilitate the development of future jetting devices. The purpose of this study is to propose a novel simulation framework and to show that it captures the main effects such as droplet shape, volume and speed. In the framework, the time dependent flow and the fluid-structure interaction between the suspension, the moving piston and the deflection of the jetting head is simulated. The system is modelled as a two phase system with the surrounding air being one phase and the dense suspension the other. Hence, the non-Newtonian suspension is modelled as a mixed single phase with properties determined from material testing. The simulations were performed with two coupled in-house solvers developed at Fraunhofer-Chalmers Centre; IBOFlow, a multiphase flow solver and LaStFEM, a large strain FEM solver. Jetting behaviour was shown to be affected not only by piston motion and fluid rheology, but also by the energy loss in the jetting head. The simulation results were compared to experimental data obtained from an industrial jetting head.
Fraunhofer-Chalmers Research Centre for Industustrial Mathematics
Technical Library | 2021-07-13 19:59:34.0
We have investigated the processing of lead-zirconate-titanate-based thick films by inkjet printing Pb (Zr0.53Ti0.47)0.98Nb0.02O3 with a 6 mol% excess of PbO nanosized powder dispersed in water. Differentwaveforms were employed to determine the optimum size and shape of the drops. A uniform, defect-free pattern with dimensions of 4 mm × 4 mm can be printed using 20 V and a drop spacing of 20 μm. The inkjet-printed films were heated to 400 °C to remove the organics and subsequently sintered at 750 and 850 °C. The correlations between the density, grain size and electromechanical properties of the thick films and bulk ceramics are qualitatively discussed. A thickness coupling factor of 46% was obtained for a 15-μm-thick film sintered at low temperature of 850 °C, which is comparable to the value of the bulk ceramic with an identical nominal chemical composition. Our results are important for the economic and environmental-benign printing of piezoelectric materials applicable in variety of electronic devices, such as sensors, actuators, transformers, piezoelectric energy harvesters and transducers.
Technical Library | 2023-06-12 18:33:29.0
This paper presents a real-time predictive approach to improve solder paste stencil printing cycle decision making process in surface mount assembly lines. Stencil cleaning is a critical process that influences the quality and efficiency of printing circuit board. Stencil cleaning operation depends on various process variables, such as printing speed, printing pressure, and aperture shape. The objective of this research is to help efficiently decide stencil printing cleaning cycle by applying data-driven predictive methods. To predict the printed circuit board quality level, a recurrent neural network (RNN) is applied to obtain the printing performance for the different cleaning aging. In the prediction model, not only the previous printing performance statuses are included, but also the printing settings are used to enhance the RNN learning. The model is tested using data collected from an actual solder paste stencil printing line. Based on the predicted printing performance level, the model can help automatically identify the possible cleaning cycle in practice. The results indicate that the proposed model architecture can predictively provide accurate solder paste printing process information to decision makers and increase the quality of the stencil printing process.
Technical Library | 2023-12-18 21:07:29.0
Selective soldering utilises a nozzle to apply solder to components on the underside of printed circuit boards (PCBs). This nozzle can be moved to either perform dips (depositing solder to a single component) or draws (applying solder to several components in a single movement). The selective soldering methodology thereby allows the process to be tailored to specific joints and allows multiple nozzle types to be used if required on the circuit board. Nozzles can vary by size (internal diameter) and shape (making them suitable for different process types). This is all dictated by board design and process requirements. Selection of the nozzle type is dependent upon the product to be soldered and the desired cycle time. Examples of different nozzle types are shown here. Hand-load selective systems must be programmed with the parameters for multiple solder joints. However, many in-line systems are designed to be modular. This modularity allows for multiple solder stations with different conditions/nozzles to achieve low cycle times. Figure 1 shows the two distinct types of selective soldering systems offered by Pillarhouse International Ltd.
Technical Library | 2020-09-02 22:02:13.0
With the adoption of Wafer Level Packages (WLP) in the latest generation mobile handsets, the Printed Circuit Board (PCB) industry has also seen the initial steps of High Density Interconnect (HDI) products migrating away from the current subtractive processes towards a more technically adept technique, based on an advanced modified Semi Additive Process (amSAP). This pattern plate process enables line and space features in the region of 20um to be produced, in combination with fully filled, laser formed microvias. However, in order to achieve these process demands, a step change in the performance of the chemical processes used for metallization of the microvia is essential. In the electroless Copper process, the critical activator step often risks cross contamination by the preceding chemistries. Such events can lead to uncontrolled buildup of Palladium rich residues on the panel surface, which can subsequently inhibit etching and lead to short circuits between the final traces. In addition, with more demands being placed on the microvia, the need for a high uniformity Copper layer has become paramount, unfortunately, as microvia shape is often far from ideal, the deposition or "throw" characteristics of the Copper bath itself are also of critical importance. This "high throwing power" is influential elsewhere in the amSAP technique, as it leads to a thinner surface Copper layer, which aids the etching process and enables the ultra-fine features being demanded by today's high end PCB applications. This paper discusses the performance of an electroless Copper plating process that has been developed to satisfy the needs of challenging amSAP applications. Through the use of a radical predip chemistry, the formation, build up and deposition of uncontrolled Pd residues arising from activator contamination has been virtually eradicated. With the adoption of a high throwing power Copper bath, sub 30um features are enabled and microvia coverage is shown to be greatly improved, even in complex via shapes which would otherwise suffer from uneven coverage and risk premature failure in service. Through a mixture of development and production data, this paper aims to highlight the benefits and robust performance of the new electroless Copper process for amSAP applications
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