How do you control the coating thickness in the dipping process and what is the tolerance of the coating thickness?
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.
How do I monitor the viscosity?
What is the loading mechanism for the DS100 dip system?
Can the DS100 utilise in line curing?
Can I horizontally dip into the conformal coating using the DS101?
Is the argon blanket an important option for the DS101?
How often do you recommend a viscosity check on the conformal coating material in the DS101 tank?
SCH have an option of automatic viscosity control and top up system for the DS101 dip coating system. Can you advise how this works?
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.
How is the height of the conformal coating material in the tank controlled on the DS101 dip coating system?
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!).