Technical Library | 2015-06-30 16:07:12.0
Robotics for automated fluid dispensing have the ability to apply a variety of materials including epoxy, silicone, and acrylic coatings. These materials are extensively used in today’s high-speed fluid dispensers for the electronics industry. Whether a dispenser is applying epoxy or another material, the central concept for applying any form of material remains the same. Specific points of an item being dispensed onto are programmed into the dispensing system. The automated fluid dispensers software interprets the programmed information and keeps the travel path in memory. A robotic arm moves fluid dispensing nozzles along this travel path and applies epoxy onto the surface of the item with precise accuracy. Machine speed can be adjusted to emit varying amounts of epoxy. The overall application process is auto-regulating and will not be disrupted.
Technical Library | 2015-08-18 14:02:37.0
What is UV Curing? “Ultraviolet (UV) light is an electromagnetic radiation with a wavelength from 400 nm to 100 nm, shorter than that of visible light but longer than X-rays.” (Source: Wikipedia). Ultraviolet or UV curing is used to create a photochemical reaction using high intensity Ultraviolet (UV) energy or “light” to quickly dry inks, adhesives or conformal coatings. Most materials cure with a UV wavelength around 350 ~ 400nm although some materials require UVC energy near 255nm. There are many advantages to using UV curing over other traditional methods of curing. Not only will it increase production speed, it assists in creating a better bond, and improves scratch and solvent resistance. When compared to other methods of curing, UV curing generates a more reliable cured product at a much higher rate of production in a considerably shorter period of time.
Technical Library | 2017-04-13 16:14:27.0
The drive to reduced size and increased functionality is a constant in the world of electronic devices. In order to achieve these goals, the industry has responded with ever-smaller devices and the equipment capable of handling these devices. The evolution of BGA packages and leadless devices is pushing existing technologies to the limit of current assembly techniques and materials.As smaller components make their way into the mainstream PCB assembly market, PCB assemblers are reaching the limits of Type 3 solder paste, which is currently in use by most manufacturers.The goal of this study is to determine the impact on solder volume deposition between Type 3, Type 4 and Type 5 SAC305 alloy powder in combination with stainless steel laser cut, electroformed and the emerging laser cut nano-coated stencils. Leadless QFN and μBGA components will be the focus of the test utilizing optimized aperture designs.
Technical Library | 2017-11-22 12:38:51.0
The use of copper foils laminated to polyimide (PI) as flexible printed circuit board precursor is a standard practice in the PCB industry. We have previously described[1] an approach to very thin copper laminates of coating uniform layers of nano copper inks and converting them into conductive foils via photonic sintering with a multibulb conveyor system, which is consistent with roll-to-roll manufacturing. The copper thickness of these foils can be augmented by electroplating. Very thin copper layers enable etching fine lines in the flexible circuit. These films must adhere tenaciously to the polyimide substrate.In this paper, we investigate the factors which improve and inhibit adhesion. It was found that the ink composition, photonic sintering conditions, substrate pretreatment, and the inclusion of layers (metal and organic) intermediate between the copper and the polyimide are important.
Technical Library | 2019-03-06 21:26:14.0
Electronic assemblies use a large variety of polymer materials with different mechanical and thermal properties to provide protection in harsh usage environments. However, variability in the mechanical properties such as the coefficient of thermal expansion and elastic modulus effects the material selection process by introducing uncertainty to the long term impacts on the reliability of the electronics. Typically, the main reliability issue is solder joint fatigue which accounts for a large amount of failures in electronic components. Therefore, it is necessary to understand the effect of polymer encapsulations (coatings, pottings and underfills) on the solder joints when predicting reliability.This paper presents the construction and validation of a thermo-mechanical tensile fatigue specimen. The thermal cycling range was matched with potting expansion properties in order to vary the magnitude of tensile stress imposed on solder joints
Technical Library | 2023-05-22 17:46:29.0
Over the past several years, much research has been performed and published on the benefits of stencil nano-coatings and solvent under wipes. The process improvements are evident and well-documented in terms of higher print and end-of-line yields, in improved print volume repeatability, in extended under wipe intervals, and in photographs of the stencil's PCB-seating surface under both white and UV light. But quantifying the benefits using automated Solder Paste Inspection (SPI) methods has been elusive at best. SPI results using these process enhancements typically reveal slightly lower paste transfer efficiencies and less variation in print volumes to indicate crisper print definition. However, the improvements in volume data do not fully account for the overall improvements noted elsewhere in both research and in production.
Technical Library | 2013-06-20 14:33:12.0
With today's consumer technologies driving the need for denser and more compact devices, the assembly process for surface mounted devices has becoming increasingly more difficult. With the mixture of components requiring a broader range of print deposition volume, various techniques are in use in an attempt to ensure consistent and appropriate paste volume is achieved. Some of these techniques include step etching a stencil locally on a targeted device, promoting electroformed smooth wall nickel stencils, through to laser cutting newer grade stencil materials. This paper focuses on the relevant attributes that affect the properties of solder paste release and introduces the effects of surface free energy with respect to key elements that make up the stencil printing process.
Technical Library | 2020-08-13 01:12:57.0
The solar industry has driven solutions that result in electronics systems that are required to perform in outside environments for over 25 years. This industry expectation has resulted in solutions to protect the electronics from failure that can result from interaction with moisture, and various chemicals leading to corrosion and shorting of the systems. Potting and encapsulation compounds can impart the very high level of protection from environmental, thermal, chemical, mechanical, and electrical conditions that the solar applications demand.
Technical Library | 2023-04-17 21:37:32.0
Ionic contamination is a leading cause in the degradation and corrosion of electronic assemblies, leading to lifetime limitation and field failure (Fig. 1). Ionic residue comes from a variety of sources shown in Fig. 2 opposite: Examples of ionic contaminants: * Anions * Cations * Weak Organic Acid
Technical Library | 2017-12-11 22:31:06.0
Typical printed circuit board assemblies (PCBAs) processed by reflow, wave, or selective wave soldering were analysed for typical levels of process related residues, resulting from a specific or combination of soldering process. Typical solder flux residue distribution pattern, composition, and concentration are profiled and reported. Presence of localized flux residues were visualized using a commercial Residue RAT gel test and chemical structure was identified by FT-IR, while the concentration was measured using ion chromatography, and the electrical properties of the extracts were determined by measuring the leak current using a twin platinum electrode setup. Localized extraction of residue was carried out using a commercial C3 extraction system. Results clearly show that the amount and distribution of flux residues are a function of the soldering process, and the level can be reduced by an appropriate cleaning. Selective soldering process generates significantly higher levels of residues compared to the wave and reflow process. For conformal coated PCBAs, the contamination levels generated from the tested wave and selective soldering process are found to be enough to generate blisters under exposure to high humidity levels.
