Technical Bulletin February

       

Technical Bulletin February

     

Setting up a Conformal Coating Dip Facility

  The set up of a turnkey dip coating facility for companies wishing to coat in house can be complicated. Fortunately SCH   relatively Technologies can offer advice and equipment   such as the DS101 to achieve a perfect conformal coating dip process with the minimum   of effort.  

    General Requirements for Conformal Coating  

The coating room area should be clean and dust   free since PCBs are susceptible to particles sticking to the drying coating. The temperature   range should be reasonably controlled within   sensible limits as this can have critical effects on the viscosity of the coating materials.            

Perhaps even more importantly however, is the humidity. It is crucial that this is regulated to maintain a level of above 35% (for ESD reasons) and below 55% due to moisture issues which can affect the coating integrity and the application method. Extraction will be required if solvent based coatings are used and bifurcated fans should be used to ensure that unnecessary explosions are avoided. Consultation with an extraction company would be necessary and SCH can recommend a suitable company for help. With regards dipping solvents and electrical points there are no specific HSE rules and guidelines for the process. The dip system itself is completely pneumatically driven so avoids any explosion problems within the system. However, consideration should be given to nearby electrical sockets, appliances etc, especially if solvents are used in the dip coating system.

             

What do we provide?

SCH Technologies can offer conformal coating services, conformal coating equipment and Humiseals   great range of conformal coating materials. We will be happy to answer any of your questions and we’ve got the experience to solve any of your conformal coating headaches. Don’t hesitate to and we’ll help to ease the pain of conformal coating.

        

Dip Conformal Coating Equipment Required

 

A basic conformal coating facility could simply be an extracted area, a UV source and the coating. However, for setting up a Dip Conformal Coating Facility that can produce repeatable, high quality results there are several pieces of kit that will aid the operator and ensure that the best results are achieved. A basic set up could include:

           

Dip Coating System: For controllable, repeatable application of the coating to the PCB. Zahn cup kit:

Curing Cabinet:

UV Inspection Booth:

Solvent Exposure Alarm: SEA 500

For control of the viscosity of the conformal coating in the dip tank. For storage of drying PCBs after application to ensure minimal contamination from the atmosphere. For inspection of the fluorescing coating under long wave UV to ensure coating coverage to IPC A 610 Class III standards or alternatives. For monitoring the exposure of the operators during the process to ensure that they are alerted of any issues and a permanent record of the process is created.

 

     

The Conformal Coating Dip System

 

  The conformal coating dip machine should be designed to allow controlled dipping of the PCBs   which provides repeatable coating application. Both the insertion and withdrawal rates should be adjustable down to 1”/min speed although most coatings use a range of 6-9”/min. The viscosity of the coating and the withdrawal rate dictate the final thickness of the dry coating on the board and by knowledge of the two values repeatable control of the thickness is possible. A dwell time should be offered to allow time for penetration of the coating under difficult low-profile components. The tank itself should be weir driven giving a skin free, controllable material height at which to lower the product into the dip tank. There should be a lid on the tank for minimising losses and effects of contamination. The weir design should make cleaning easy and the tank should be easily removable to allow ad hoc cleaning or replacement of coating.

                   

The system shown is the DS101 Dip Coating   System.     SCH Technologies is a Trading Name of SCH Services Limited

  Newburgh Building, McLintock Way, Barnsley, South Yorkshire. S70 6BF Tel: +44 (0)1226 297711 Fax: +44 (0)1226 297733 www.conformalcoating.co.uk

SCH Technologies are ISO9001 and ISO14001certified

   

Curing Cabinet Once coated the PCBs should be stored in a cabinet whilst the coating dries. The curing cabinet has four main roles which are: 1. To extract the air around the PCBs to aid drying and remove dangerous fumes 2. To ensure that the PCB’s are held still and the coating does not flow 3. To stop the PCBs touching to avoid damaging the coating 4. To stop any particles in the atmosphere from settling onto the PCBs and sticking The system shown is the CC100 curing cabinet.    

UV Inspection Booth To inspect to IPC-A -610 standards the operator needs to use UV lighting. Also, if there are any finishing requirements to take place extraction will be required. The operator has a dark, enclosed area to study the PCB with the UV lighting intensity maximised using a UV-transmitting plastic window in the ceiling. The system shown is the IB100 single inspection booth.

Solvent Exposure Alarms (SEA) The SEA range of solvent monitoring detectors allows operators to be aware of any breaches in exposure limits. Also, the SEA 500 will data log the results and ensure that the operators have a clear record of their exposure. The system shown is the SEA 500 measurement, alarm and data logging system.   SCH Technologies is a Trading Name of SCH Services Limited

  Newburgh Building, McLintock Way, Barnsley, South Yorkshire. S70 6BF Tel: +44 (0)1226 297711 Fax: +44 (0)1226 297733 www.conformalcoating.co.uk

SCH Technologies are ISO9001 and ISO14001certified