Preparing the base substrate for coating and the coating process
Initial cleanse
Simtal Ltd. has vast knowledge and knowhow in cleaning circuit boards and other devices made of a variety of materials. They also make sure to always remain updated regarding the latest cleaning techniques.
The most common methods are based on solvents with varying concentrations and grades of cleanliness, water at different levels of hardness, as well as various combinations of specialized chemicals. In cases where a thorough and extreme cleanse is required – we make use of more advanced equipment, such as plasma etching and cleaning (using the required energy spectrum) as well as ultra-sonic equipment. Apart from these common methods, Simtal also has experience using other advanced methods developed in-house.
In coordination and with the prior approval of the infrastructure’s design and development team, for each infrastructure Simtal suit a specific cleaning process. Simtal’s planning process verifies full compliance with customer requirements and the infrastructure’s materials.
Improved adhesion
Perylene is an inert product. In order for it to adhere to a device, a variety of processes have been developed over the years to improve adhesion. These processes are usually run on the infrastructure, either by immersion in an alcoholic detergent mixed with materials that improve adhesion, or by making changes to the surface of the infrastructure. Other methods, exclusive to Simtal, may be applied depending on the infrastructure.
Masking
The completion of the cleansing process brings the infrastructure to the next stage of treatment – the masking station: the remarkable penetrability of Parylene during the coating process enables the highest level of coating – while the areas that should not be coated must be carefully masked. Simtal has over 3400 different masking materials (adhesives, silicones, masking tapes, bolt caps and more) suited for masking various infrastructures of a variety of materials and complex architectures. Simtal’s advantage is in its accumulated expertise and knowhow of the most effective and reliable masking techniques and materials.
Jigging - Occupancy and Mounting
Once the masking is complete, we reach the occupancy stage (‘Jigging’) using a carrier – in applications where much importance is placed on the amount of infrastructure coated in each run (batch) – correct occupancy can significantly reduce costs.
Coating
Performed at ambient temperatures after priming, the dimer (raw material) is cracked into a monomer and fed at a rate that polymerizes (the actual coating) between a quarters to 5 microns an hour. All controlled by the developer / operator.
Dismantling the mounted substrates and removing the masking
At the end of the coating process the various masking materials are removed in order to expose the “no coating needed areas”. Simtal has developed various methods to accurately remove masks, preventing any damage to the components.
Final Testing
Final testing of the coating quality is one of the foundation blocks of the coating process. This part of the process changes according the different parameters used during the coating run; as its range of characteristics allow the coated product to be used or applied in ways, which would not have been possible with other conformal coatings. This makes the Parylene coating into an integral part of the chemical and mechanical infrastructure, rather than a simple protective coating.
Therefore, some of the accepted testing within the coating industry aren’t applicable to Parylene. Some basic tests do apply, while others are determined together with the client and derived from the features and characteristics which the coating was required to provide.
Thickness testing – There are a few common ways of executing thickness tests for Parylene:
- Using a degree altimeter (Pantostepper) – An apparatus that sketches and copies an enlarged sketch of the infrastructure’s surface profile, “climbing” over the coating layer and measuring its thickness.
- Using a magnetic field meter (Eddy Current) – A test that measures the change in capacity and intensity of the magnetic field of the infrastructure, in respect to the distance from the metal (a distance that simulates the thickness of the coating. Using a smart algorithm it translates it into the exact thickness of the coating).
- Using a micrometer – A simple manual test of the coating’s thickness, considered less precise but excellent when required to establish the general measurements.
