Technical Library | 2017-12-07 10:35:50.0
Electronics manufacturers protect their circuit boards with conformal coatings. Conformal coatings serve as a barrier from environmental hazards and internal shorts, tin whiskers, and corrosion at the board level. Within conformal coatings different material chemistries specialize in shielding from an array of hazards and can be applied by multiple methods. The most common method is atomized spray which disperses the material into a fine mist. Alternatively, non-atomized coating controls the materials' dispense shape while maintaining the original liquid form. While some applications demand atomized spray and other scenarios overlap between atomized and non-atomized coating, this paper focuses on the circumstances where materials are ideally suited for non-atomized, selective coating.
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 | 2020-02-03 17:37:36.0
Accurate impact testing is a key component to establishing that a product is not only reliable, but durable in an end-use environment. ACI Technologies tested a high-g circuit board to demonstrate component durability and ruggedization for guided munitions. The Lansmont Model 23 Shock Test System customized with a Dual Mass Shock Amplifier was used for this testing (Figure 1).
Technical Library | 2023-09-23 22:31:52.0
Dry boxes can be implemented at various points within the Mfg. environment; for med-long term inventory, or for short term handling on the production floor, and in some cases (with certain conditions) as a process replacement for baking. Bare boards, raw components and partially assembled PCB's can benefit from ultra-low humidity storage.
Technical Library | 1999-08-27 09:27:10.0
Conformal coating is a material that is applied to electronic products or assemblies to protect them from solvents, moisture, dust or other contaminants that may cause harm. Coating also prevents dendrite growth, which may result in product failure. This paper will discuss the variables that affect the application of conformal coatings, and review in detail those variables that impact the process of selective coating of printed circuit boards.
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 | 2019-05-31 14:19:24.0
ACI Technologies (ACI) characterized the reliability of surface mount RF components. The RF frequency band of interest was the X band (10.7 to 11.7GHz). A two pronged test for reliability of circuit card assemblies (CCA) was designed for both extreme thermal cycling and vibration. The rapid thermal cycling and extreme vibration testing simulates the total stress encountered by the assembly over the life of the product but accomplishes it in a relatively short period of time. In order to perform the reliability testing, a test vehicle consisting of a printed circuit board with test structures and components, was designed, fabricated, and assembled at ACI.
Technical Library | 2019-06-03 15:32:40.0
ACI Technologies was pleased to assist a customer by conducting elemental analysis on several assemblies displaying severe corrosion. Several board assemblies had failed in the field and exhibited areas of corrosion in close proximity to onboard components. The most common source of corrosion on electronic assemblies is residual flux. Fluxes are specific chemistries applied during the soldering process which improve the wetting of the solder to both the pad and component when forming the solder joint. They can be highly reactive chemicals that, if left on the assemblies, can lead to corrosion, electrical degradation, and decreased reliability. In the presence of moisture and electrical bias, flux residue can enable dendritic growth as a result of electrochemical migration (ECM).
Technical Library | 2019-10-16 10:20:25.0
A major goal of the development of advanced packaging technology is to reduce the size, weight, and power consumption of electronics components using state-of-the-art commercial technologies. One of the novel concepts involves the use of all three spatial dimensions when designing and producing new systems. In the past, electronic structures tended to be two dimensional in nature. Generally speaking, individually packaged integrated circuit (IC) dies were interconnected on printed circuit boards. Techniques such as die and package stacking naturally contribute to a reduction of the spatial footprint of any given electronic system design.
Technical Library | 2019-12-05 13:30:46.0
Conformal coatings are regularly employed to protect the surface of a soldered printed circuit board assembly from moisture, chemicals in the PCBA's service environment, and foreign objects or debris. Conformal coatings are nonconductive and therefore cannot be placed on any location where electrical contact will be required, such as connector pins, test points, and sockets. Conformal coatings are also not permitted on any mechanical interface location, such as mounting holes or brackets, to assure the proper fit between items in the final assembly. In order to apply conformal coatings to an assembly and comply with the restrictions on keep-out areas, masking is employed to protect those surfaces.
