Technical Library | 2019-05-24 09:22:59.0
There is a smaller process window and a much narrower margin of error when creating and using lead-free reflow profiles for surface mount parts on printed circuit boards (PCBs). Solder balls, dewetting, tombstones, voids, and head-on-pillow problems will occur much more frequently because lead-free alloys behave differently than eutectic pastes. Problems are compounded due to the extra heat necessary for some lead-free pastes to reach their melting points.
Technical Library | 2019-06-17 15:09:43.0
Very often pick and place machines are programmed using CAD data. This data increases the accuracy, precision, and repeatability of its component placement objectives. CAD data makes fine pitch and small component assemblies repeatable, but cannot adjust to a particular board unless it is exactly the same size and shape of the original board used for programming. The process by which printed circuit boards (PCBs) are made only allows some minor changes inboard size and shape, but these small differences are enough for parts to be misplaced. For this reason we use fiducial marks to increase the chances of precise component alignment.
Technical Library | 2019-05-23 10:42:00.0
Why identify flux residues? The primary purpose of flux is to reduce species of metal oxides from solderable surfaces, and to act as a mechanism for lifting and removing debris. If the assembly is not properly cleaned after manufacturing, flux may continue to reduce metals and may eventually corrode the assembly. When the assembly is powered, the metal ions may precipitate along electromagnetic field lines and form dendritic shorts. In addition, the presence of residue can alter the insulation properties of a board, affect the adhesion of the conformal coating, or interfere with the moving parts of the assembly. In radio frequency (RF) applications, flux may change the RF properties on the surface of the printed circuit board (PCB) such as the dielectric strength, surface resistance, and Q-resonance.
Technical Library | 2020-03-09 10:50:17.0
A customer called the Helpline seeking advice for cleaning no-clean fluxes prior to applying a conformal coating. The customer's assemblies were manufactured with a no-clean rosin based solder paste (ROL0) and were cleaned with an isopropyl alcohol (IPA) wash. After cleaning, a white residue was sometimes found in areas with high paste concentrations and was interfering with the adhesion of the conformal coating (Figure 1). For conformal coatings to adhere properly, the printed circuit board (PCB) surface must be clean of fluxes and other residues. In addition, ionic contamination left by flux residues can lead to corrosion and dendrite growth, two common causes of electronic opens and shorts. Other residues can lead to unwanted impedance and physical interference with moving parts.
Technical Library | 2021-09-01 15:31:39.0
The long-standing trend in the electronics industry has been the miniaturization of electronic components. It is projected that this trend will continue as Original Equipment Manufacturers (OEMs) and Electronic Manufacturing Service (EMS) providers strive to reduce "real estate" on printed circuit boards. Typically, the miniaturization of components can be achieved by integration or size reduction. At present, size reduction is considered to be more cost effective and flexible than integration. Passive components, which are used in limiting current, terminating transmission lines and de-coupling switching noise, are the primary focus in size reduction due to their variety of uses.
Technical Library | 2005-05-16 12:09:02.0
Low cost techniques for building prototype and low volume SMT printed circuit boards.
Technical Library | 2017-09-28 16:36:33.0
These nano-coatings also refine the solder paste brick shape giving improved print definition. These two benefits combine to help the solder paste printing process produce an adequate amount of solder paste in the correct position on the circuit board pads. Today, stencil aperture area ratios from 0.66 down to 0.40 are commonly used and make paste printing a challenge. This paper presents data on small area ratio printing for component designs including 01005 Imperial (0402 metric) and smaller 03015 metric and 0201 metric chip components and 0.3 mm and 0.4 mm pitch micro BGAs.
Technical Library | 2023-05-02 18:54:30.0
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.
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 | 2015-05-28 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.
