Conformal coating is a protective treatment applied to assembled electronic boards (PCBA) through the dispensing of a “plastic” film (made of resins), usually transparent.
Why is Conformal Coating Necessary?
This treatment, in addition to improving electrical insulation and preventing oxide formation on exposed metal points of the PCB, serves to protect boards against various environmental factors that can negatively affect the functionality of electronic boards. Humidity, dirt, airborne conductive dust, saline environments, etc…
There are different technologies in the market (besides the acrylic one, the “silicone” technology is also widely used). Today we’ll discuss the most widespread technology, the acrylic one.
The Advantages of Acrylic Conformal Coating
The success of acrylic technology is due to several factors, which we will examine below:
- Acrylic technology polymerizes very quickly at room temperature, usually within a few minutes.
- It’s a technology resistant to fungi and mold.
- During polymerization, unlike other technologies, it doesn’t produce any overheating (due to the chemical process).
- It’s “the best available technology for ‘protection against’ moisture”.
- It has good dielectric properties (insulation).
- It performs well in terms of working temperature.
- It’s among the easiest technologies to rework if needed.
- It’s among the easiest to manage at the production level.
- It’s an established technology with low costs.
Conformal coating also improves board protection against thermal cycles and mechanical shock!
Conformal Coating Application Methods
Conformal coating can be applied in three main ways. This depends on the board complexity, the number of pieces to produce, any masking requirements, and/or other factors. The three methods are:
- Brush application
- Dip coating
- Spray (Manual and/or automatic)
We will focus particularly on automatic spray application using multi-axis Cartesian systems (robots). This technology is the most precise, the most repeatable, and allows avoiding manual masking while achieving controlled and consistent thickness across the entire board.
Using a system with automatically set parameters eliminates dependency on individual operator skills. This results in a higher quality and more repeatable process through a well-defined and programmed dispensing head path.
…Some Info where Acrylic Technology is less or not Effective
After discussing the undeniable advantages, there are some cases where acrylic technology is not suitable for use, as it is less effective. For example, where solvents are present or where operating temperatures are high (above 100°C) or in “harsh” environments, acrylic technology is not the most suitable.
Prime, in pursuit of continuous technological investments, has focused on an autonomous work cell equipped with a robotized system with automatic loading and unloading. On this page you can verify the capabilities of our automatic system.
The “film” deposition is performed precisely and repeatedly through a selective conformal coating system. The thickness is also controlled (typically for Acrylic technology, it ranges from 25/30 microns up to 50/60 microns).
The maximum dimensions of electronic boards are 450mm x 450mm. We must also consider a maximum component height of 50 mm on both the top and bottom sides.
This allows us to perform a precise, repeatable process automatically without wasting time on manual activities such as “masking” and subsequent “unmasking”.
…………. where electronic boards need protection against dust and particularly humid environments, “Acrylic” conformal coating helps us improve the reliability of our products, including from a mechanical perspective.
