Technical Library | 2015-07-21 13:50:37.0
Achieving an even coat at the right desired thickness is a major challenge when it comes to applying conformal coating to a Printed Circuit Board (PCB). Applying a coating too thin will ultimately render the electronic assembly vulnerable to potential environmental risks therefore defeating the purpose of the coating. Apply the coat too thick, and it could leave the electronic specific components non-functional therefore destroying the electronic assembly entirely. Coating thickness must meet quality specifications. Measurements for coating thickness may be taken while film is dry or wet. Once measurements are recorded, thickness is compared to quality specifications and fluid dispensing automation machinery is calibrated as necessary. There are a handful of methods for measuring conformal coating thickness that are commonly used in the Electronic Manufacturing Services (EMS) and Original Electronic Manufacturer (OEM) industries. A few commonly used methods for checking conformal coating thickness include:
Technical Library | 2013-10-13 10:54:13.0
The measurement of the conformal coating thickness on a printed circuit board (PCB) to ensure internal and international standards are met is now a critical factor in conformal coating process control. There are several methods for measurement of conformal coating thickness and they fall into two categories. These categories are wet film measurements applied during coating application and dry film measurements made after the coating is dried enough not to damage the coating.
Technical Library | 2013-05-30 17:33:26.0
This paper covers the following topics: The Measurement Application, Measurement Requirements, Measurement Problems, Measurement Results, Reference Samples, Conclusions
Technical Library | 2016-05-19 16:03:37.0
As consumers become more reliant on their handheld electronic devices and take them into new environments, devices are increasingly exposed to situations that can cause failure. In response, the electronics industry is making these devices more resistant to environmental exposures. Printed circuit board assemblies, handheld devices and wearables can benefit from a protective conformal coating to minimize device failures by providing a barrier to environmental exposure and contamination. Traditional conformal coatings can be applied very thick and often require thermal or UV curing steps that add extra cost and processing time compared to alternative technologies. These coatings, due to their thickness, commonly require time and effort to mask connectors in order to permit electrical conductivity. Ultra-thin fluorochemical coatings, however, can provide excellent protection, are thin enough to not necessarily require component masking and do not necessarily require curing. In this work, ultra-thin fluoropolymer coatings were tested by internal and industry approved test methods, such as IEC (ingress protection), IPC (conformal coating qualification), and ASTM (flowers-of-sulfur exposure), to determine whether this level of protection and process ease was possible.
Technical Library | 2022-01-26 15:22:33.0
Reliability of conformal coatings used to mitigate tin whisker growth depends on their ability to contain tin whiskers. Two key material properties required to assess the reliability of a polyurethane coating are documented experimentally: adhesion strength and puncture strength. A modified blister test using a predefined blister area is employed to assess the adhesion strength and a puncture test is employed to evaluate the puncture strength of the coating. After measuring the properties at time zero, the coatings are subjected to accelerated testing conditions (high temperature/humidity storage and temperature cycling) and the degradations of the coating properties are documented.
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.
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