Conformal coating protects printed circuit board assemblies (PCBAs) used in automotive or outdoor environments from moisture, dust, and chemicals. While dip coating the entire board provides incredibly robust protection, it is prone to trapping air bubbles (voids) under complex components. Here is an in-depth look at how conformal dip coats protect electronics, and how precise speed and angle controls on your dip coater eliminate air bubbles and prevent insulation failures.
1. The Advantages of Protecting PCBs with a Dip Coat
Unmatched Penetration for Complex Components
When applying conformal coatings via spray, “blind spots” are inevitable. Spray simply cannot reach behind tall capacitors or underneath the tight pins of an IC chip. If even a tiny area is left uncoated, moisture will eventually get in and cause a short circuit.
The greatest advantage of dip coating is that the entire board is submerged directly into the resin (such as silicone or urethane). There are no blind spots. No matter how densely packed the components are, the liquid penetrates every crevice, forming a flawless moisture and insulation barrier.
2. The Biggest Enemy of Conformal Coating: Bubbles (Voids)
How Air Gets Trapped Under Components
While dip coating provides superior coverage, it comes with one major challenge: entrapped air bubbles (voids).
When you submerge the board, air often gets trapped underneath IC chips or inside connector gaps with nowhere to escape. If the resin cures with these bubbles still inside, those areas are effectively left bare. These voids act as starting points for corrosion and insulation failure. The key to a high-quality conformal coating is successfully venting this air.
3. Venting Bubbles with Dip Coater Speed and Angle Controls
Eradicating Insulation Failures During the Dipping Phase
To prevent air entrapment, controlling the insertion phase (lowering the part into the liquid) with your dip coater is absolutely critical.
First, the board should never be dipped perfectly flat. It must enter the liquid at an optimized angle, allowing the air to escape upwards. Second, the dip coater must lower the board at a very slow, controlled “dipping speed” that matches the rate at which the air is pushed out. SDI dip coaters allow you to program this downward dipping speed completely independently from the withdrawal speed. This ensures that even the most complex PCBs receive a flawless, bubble-free dip coating every time.
▼ Program Your Downward Speeds: Explore SDI’s Dip Coater Features https://www.sdicompany.com/en/