Technical Library | 2020-12-07 15:26:06.0
Temperature cycling testing is a method of accelerated life testing done to PCCs that are exposed to normal operation temperature variations over its lifetime. During the testing, intermittent "open" failures can first occur at the hot and cold extremes of the test, exposing weaknesses in the design and assembly. A poor/weak solder joint fatigues, a via trace or barrel cracks, loose connections or a component fails all causing an intermittent open. When not at extreme temperatures, the PCC assembly relaxes, the "open" closes creating electrical connectivity. If you are monitoring the PCC under test in-situ you will know that an intermittent failure has occurred, and the test could be stopped for inspection. If in-situ monitoring was not implemented, you would not know if there were intermittent failures or not. The PCC gets powered up and works fine at room temperature.
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 | 2023-06-02 14:13:02.0
This work examines the use of dual-material fused filament fabrication for 3D printing electronic componentsand circuits with conductive thermoplastic filaments. The resistivity of traces printed fromconductive thermoplastic filaments made with carbon-black, graphene, and copper as conductive fillerswas found to be 12, 0.78, and 0.014 ohm cm, respectively, enabling the creation of resistors with valuesspanning 3 orders of magnitude. The carbon black and graphene filaments were brittle and fracturedeasily, but the copper-based filament could be bent at least 500 times with little change in its resistance.Impedance measurements made on the thermoplastic filaments demonstrate that the copper-based filamenthad an impedance similar to a copper PCB trace at frequencies greater than 1 MHz. Dual material3D printing was used to fabricate a variety of inductors and capacitors with properties that could bepredictably tuned by modifying either the geometry of the components, or the materials used to fabricatethe components. These resistors, capacitors, and inductors were combined to create a fully 3Dprinted high-pass filter with properties comparable to its conventional counterparts. The relatively lowimpedance of the copper-based filament enabled its use for 3D printing of a receiver coil for wirelesspower transfer. We also demonstrate the ability to embed and connect surface mounted components in3D printed objects with a low-cost ($1000 in parts), open source dual-material 3D printer. This work thusdemonstrates the potential for FFF 3D printing to create complex, three-dimensional circuits composedof either embedded or fully-printed electronic components.
Technical Library | 2023-11-06 17:08:44.0
A new process has been developed for RF shielding on compact electronic communications devices using automated solder paste dispensing. The process is known as Shield Edge Interconnect (SEI). SEI designs enable parts to be processed though underfill before placing of the RF shield and allows more complete use of valuable PCB real estate to achieve reduced form factor requirements and/or for added components on products such as smartphones and tablets. The reduced form factor creates challenges for the assembly of those devices. This process, enabled by Speedline dispensing technology, relies on extremely accurate dispensing of solder paste on copper traces located along the outer edge of the PCB. The result is a robust process solution for SEI in which proprietary closed loop dispenser, pump, vision, and software technologies enable a high volume manufacturing (HVM) process.
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 | 2015-08-20 15:18:38.0
Increasing system integration and component densities continue to significantly reduce the opportunity to access nets using standard test points. Over time the size of test points has been drastically reduced (as small as 0.5 mm in diameter) but current product design parameters have created space and access limitations that remove even the option for these test points. Many high speed signal lines have now been restricted to inner layers only. Where surface traces are still available for access, bead probe technology is an option that reduces test point space requirements as well as their effects on high speed nets and distributes mechanical loading away from BGA footprints enabling test access and reducing the risk of mechanical defects associated with the concentration of ICT spring forces under BGA devices. Building on Celestica's previous work characterizing contact resistance associated with Pr-free compatible surface finishes and process chemistry; this paper will describe experimentation to define a robust process window for the implementation of bead probe and similar bump technology that is compatible with standard Pb-free assembly processes. Test Vehicle assembly process, test methods and "Design of Experiments" will be described. Bead Probe formation and deformation under use will also be presented along with selected results.
Technical Library | 2021-11-03 16:52:47.0
This paper proposes the integration of pulsed photonic sintering into multi-material additive manufacturing processes in order to produce multifunctional components that would be nearly impossible to produce any other way. Pulsed photonic curing uses high power Xenon flash lamps to thermally fuse printed nanomaterials such as conductive metal inks. To determine the feasibility of the proposed integration, three different polymer additive manufacturing materials were exposed to typical flash curing conditions using a Novacentrix Pulseforge 3300 system. FTIR analysis revealed virtually no change in the polymer substrates, thus indicating that the curing energy did not damage the polymer. Next, copper traces were printed on the same substrate, dried, and photonically cured to establish the feasibility of thermally fusing copper metal on the polymer additive manufacturing substrates. Although drying defects were observed, electrical resistivity values ranging from 0.081 to 0.103 Ω/sq. indicated that high temperature and easily oxidized metals can be successfully printed and cured on several commonly used polymer additive manufacturing materials. These results indicate that pulsed photonic curing holds tremendous promise as an enabling technology for next generation multimaterial additive manufacturing processes.
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