Conformal Coating Dipping: Process Controls
Why Choose Conformal Coating Dipping?
Dipping immerses the entire PCB into a coating bath, ensuring full coverage under components and over complex 3D assemblies. Additionally, it eliminates overspray, reduces waste, and can be automated easily for higher throughput. This method exemplifies the efficiency of conformal coating dipping.
Controlling Coating Thickness
Film thickness mainly depends on:
- Withdrawal speed: Slower withdrawal creates thicker films, while faster speeds produce thinner coats.
- Viscosity: Keeping viscosity consistent ensures predictable film build. Aim for a variation of no more than ±5 µm on test coupons.
- Typical example: For an acrylic at 200 cps viscosity, a withdrawal speed of 150 mm/min typically achieves 25–50 µm thickness.
Horizontal Dipping
Some assemblies can also use horizontal dipping with systems like the DS101 Dip Coating System or our custom inline dip coating systems. However, this method requires close control of drainage, masking, and part orientation to avoid defects related to the conformal coating dipping process.
Monitoring & Controlling Viscosity
Most batch dip systems rely on a Zahn cup to monitor flow time. For more advanced control, inline viscosity systems can measure and correct viscosity by adding thinner or fresh coating automatically. Thus, dipping processes for conformal coating benefit by keeping the film thickness more consistent throughout the shift.
More information is available here:
Conformal Coating Viscosity – Importance in Process Control
Dip Tank Height Control
Systems such as the DS101 dip machine manage coating height through a weir edge. Excess material flows into a sump, which helps stabilize dip level and reduces solvent loss and contamination. Proper control during conformal coating dipping is crucial.
Automated Process Controls
To further improve consistency and reduce operator input, several automation options are available:
- Automated dosing: Sensors detect low levels and feed material from sealed containers to maintain coating height.
- Material top-up systems: These systems prevent the tank from running dry, reducing interruptions and evaporation loss.
- Material heating: Holding coatings at a stable temperature (typically 20–30 °C) helps maintain viscosity and reduces bubbles during withdrawal.
- Closed-loop viscosity control: Inline systems can automatically dose thinner or fresh material to hold viscosity within specification.
Advanced Options
- Argon or dry-air blanket: This reduces solvent evaporation and helps protect moisture-sensitive coatings from ambient humidity, improving bath stability and quality.
- Filtration baskets: These capture debris and cured particles before they reach the pump or recirculation system, which helps extend material life and minimize maintenance.
- Custom board fixtures: Purpose-designed fixtures maintain immersion depth, alignment and drainage, improving repeatability across different PCB designs, illustrating the benefits of conformal coating dipping.
Best Practices for Dip Coating
- Record tank hours, board volume and thinner additions to help predict viscosity changes related to the conformal coating dipping procedure.
- Inspect the tank if the lid stays open for long periods to avoid contamination.
- Match dip settings to the coating chemistry (e.g. acrylic, silicone, water-based) to prevent defects.
Need Help with Conformal Coating Dipping?
We supply dip coating systems, subcontract coating services and training to help you control thickness, reduce waste, and improve consistency. Additionally, our team can support setup, trials, and process optimization, especially when it comes to the specifics of the conformal coating dipping technique.
Why Choose SCH Services?
Working with SCH Services gives you access to an integrated platform for Conformal Coating, Parylene and ProShieldESD solutions — including equipment, materials, subcontract services, and training. Our team brings over 25 years of direct production experience across aerospace, automotive, defense, and electronics industries.
- ✈️ 25+ Years of Experience in coating systems and application methods.
- 🛠️ End-to-End Support from setup and trials to training and troubleshooting.
- 📈 Scalable Solutions – suitable for prototypes through to high-volume production. Our expertise is particularly strong in conformal coating dipping.
- 🌍 Global Reach – supply and support across Europe, North America, and Asia.
📞 Call: +44 (0)1226 249019
✉ Email: sales@schservices.com
💬 Contact Us ›
