Technical Library | 2019-07-29 10:35:47.0
ACI Technologies can assist its users with process development and experimentation through the use of the conformal coating capabilities in the Demonstration Factory. Four types of coating processes are available at ACI Technologies: dip coating, manual spray coating, programmable spray coating, and manual brush application. (Manual brush application will not be discussed in this article.)
Technical Library | 2019-05-24 09:24:49.0
Conformal coatings are applied to Printed Circuit Board Assemblies(PCBAs) using a variety of different methods. There are six main methods of applying conformal coatings: manual spraying, automated spraying, dipping, brushing, selective coating, and vacuum deposition.
Technical Library | 2013-10-13 10:22:48.0
There are numerous factors which directly affect the conformal coating process to greater or lesser degrees. Those which have major impacts irrespective of the substrate / PCB and assemblies include choice of coating material and method of application. Whether conformal coating boards by dip, robot, batch spray or brush methods the viscosity of the coating is a critical factor in the overall process control.
Technical Library | 2019-09-24 15:41:53.0
This paper focuses on three different coating material groups which were formulated to operate under high thermal stress and are applied at printed circuit board manufacturing level. While used for principally different applications, these coatings have in common that they can be key to a successful thermal management concept especially in e-mobility and lighting applications. The coatings consist of: Specialty (green transparent) liquid photoimageable solder masks (LPiSM) compatible with long-term thermal storage/stress in excess of 150°C. Combined with the appropriate high-temperature base material, and along with a suitable copper pre-treatment, these solder resists are capable of fulfilling higher thermal demands. In this context, long-term storage tests as well as temperature cycling tests were conducted. Moreover, the effect of various Cu pre-treatment methods on the adhesion of the solder masks was examined following 150, 175 and 200°C ageing processes. For this purpose, test panels were conditioned for 2000 hours at the respective temperatures and were submitted to a cross-cut test every 500 h. Within this test set-up, it was found that a multi-level chemical pre-treatment gives significantly better adhesion results, in particular at 175°C and 200°C, compared with a pre-treatment by brush or pumice brush. Also, breakdown voltage as well as tracking resistance were investigated. For an application in LED technology, the light reflectivity and white colour stability of the printed circuit board are of major importance, especially when high-power LEDs are used which can generate larger amounts of heat. For this reason, a very high coverage power and an intense white colour with high reflectivity values are essential for white solder masks. These "ultra-white" and largely non-yellowing LPiSM need to be able to withstand specific thermal loads, especially in combination with high-power LED lighting applications. The topic of thermal performance of coatings for electronics will also be discussed in view of printed heatsink paste (HSP) and thermal interface paste (TIP) coatings which are used for a growing number of applications. They are processed at the printed circuit board manufacturing level for thermal-coupling and heat-spreading purposes in various thermal management-sensitive fields, especially in the automotive and LED lighting industries. Besides giving an overview of the principle functionality, it will be discussed what makes these ceramic-filled epoxy- or silicone-based materials special compared to using "thermal greases" and "thermal pads" for heat dissipation purposes.
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