DS101 conformal coating dip system
The DS101 Conformal coating dip system is a precision built, floor standing, conformal coating dip machine. It is designed for medium to high volume batch processing of printed circuit boards.
The system operates on compressed air only. Being entirely pneumatic the machine is safe to use with flammable materials. It also reduces the cost of expensive electronics required with explosive solvents.
The machine uses an air over oil pneumatic system for precision regulated speed control of the dip process. The automatic dip cycle process provides a smooth immersion and withdrawal rate which eliminates air entrapment and ensures an even film.
This allows a wide range of conformal coatings to be coated with repeatable high tolerance of conformal coating thickness to be achieved.
- A pneumatically driven control & pump system operating from a single air inlet to meet the most stringent H&S needs
- Front-mounted control panel for easy operation
- Constant levelling re-circulating weir system
- Multiple horizontal support rods on dipping arm
- Compatible with solvent, silicone and water based coatings
- Fume extraction hood and extraction point for spigot to be fitted
- RoHS compliant system
- Fixed steel rule to calibrate dipping speeds
- Custom tank and dip system sizes
- Customized PCB jigging and carriers
- Flow cup, viscosity tables and stop watch for material viscosity control
Standard dip tank
- Stainless steel dip tank.
- Usable area is approximately:
– 600 mm long (left to right facing machine)
– 200 mm wide (front to back facing machine)
– 300 mm deep
– 50mm wide rear weir, 150mm deep for easy clean.
- The system is constructed of powder coated steel with solvent resistant stainless tank internal panels and tank.
- System is pneumatics only. No electronics are used.
Dimensions and weight
Conformal coating dip coating FAQs
The dip speed is controlled by air over oil hydraulics which can control the speed down to 2″ per minute which is very slow and more than adequate for conformal coating. Repeatability is about getting accurate viscosity control since the withdrawal rates and viscosity control the coating thickness.
Typical speeds for conformal coatings at viscosity of 200 cps are 6″ withdrawal speed giving a 25-50um coating for an acrylic coating. This does vary from coating material to material so control measures should be put in place if accurate thickness is required.
The typical coating tolerance is depending on what you measuring on? If it is a flat coupon, then with a known viscosity of product you should be able to achieve +/- 5um.
The viscosity is monitored by utilizing a zahn type measuring cup. This is essentially an egg cup with a hole in the base on a wire. You dip the cup into the liquid and lift it out of the coating. Since the volume of the cup is known and fixed, if you time the flow of the coating out of the cup you get a relatively accurate and simple method of measuring viscosity which is certainly suitable in 99% of cases.
The PCBs are hung on the cross rods by hooks (we can supply or you make / buy your own?) or any other form of jigging ( we can custom build). The immersion and withdrawal of the cross rods is carried out by a custom piston which moves up and down at a controlled rate down to 1-2”/min since we use an air over oil system.
This is a batch dip system without inline curing. If you wish inline curing you will be adding a zero to the price. Sort of range is £30K-70K depending on size of system, rate of cure, type of material to use.
It is perfectly possible to horizontally dip PCBs using the automated batch systems such as the DS101 conformal coating dip system. There are factors such as the size of the board, the depth of dipping allowed, the type of conformal coating to be used and the masking & components on the board that must be considered but SCH regularly use this technique to minimise costs for customers.
The argon blanket is a useful accessory for overlaying conformal coatings that are sensitive to moisture such as moisture cure silicones like Dow Corning 2577. The principle is the argon gas is heavier than air and using a series of valves a blanket of argon gas is bled over the conformal coating tank, effectively trapping the solvents under the argon. This is also effective in regions of high humidity and can help prevent moisture ingress.
Checking viscosity is down to the time the tank lid is off. If it is off all day I would suggest twice a day check to ensure control. If it is a few hours then each time you start. The main issue is building a pattern of use. As you use the dip coating system, record the hours, volume of boards and the conformal coating thinners used, and chart this. Then, you will be able to anticipate when it needs checking and when it doesn’t. Also, contributes to the lean manufacture processing.
Automated viscosity control is a sophisticated process reserved for companies who are going to process a lot of PCBs and change the viscosity of the tank a lot of times in a shift or for companies who want a totally closed loop process without manual adjustment.
The viscosity system is an inline viscometer with feedback monitoring the tank constantly. There is a dosing system that would adjust the coating as required, feeding back into the conformal coating tank either conformal coating material or conformal coating thinners.
On the DS101 dip coating system there are two parts to the tank. These are the dipping area and the sump, which are separated by the weir edge. The material is pumped into the tank, over the weir into the sump. Therefore, the weir edge holds the height constant and the weir sump drops with material use.
Monitoring the weir sump depth is crucial again to learn how fast it is drained. We recommend a 25mm (1”) edge difference between the top of the weir and the sump material and keeping the material close to that avoids a wide evaporation area over the weir which means more solvent evaporation. This can also be critical with materials that do not re-dissolve into the material when dry like water based coatings. If they do dry /cure then these bits float around in the sump and then eventually could clog the pump. We would recommend using a stainless steel basket which we have designed to catch these bits like a sieve and any other bits floating (or even PCBs dropped!).
SCH can make the tank any size you want. However, there is a ratio of surface area of the tank to depth that is important. If you have too little volume of coating in relation to the surface area, the evaporation of the solvent will change the viscosity of the tank too quickly and you will constantly be monitoring it. We have no formula for this but making it too shallow could be a proble