Tag Archive | spray equipment

Designing for Selective Robotic Conformal Coating Processing: Rule 7 “Add tooling holes for the PCB if the board is not a standard shape to be supported on the fixture or conveyor”

Many PCBs can be irregular in shape or have components very close to the edge. This can make it very difficult to support the circuit board on a fixture or even worse on a moving conveyor. So, this may mean it is difficult to get the position to be repeatable. If the position is unrepeatable then the coating will go where it is not wanted.

Rule 7

Add tooling holes for the PCB if the board is not a standard shape to be supported on the fixture or conveyor.

The Rules

The Rules for Selective Conformal Coating are straightforward. Follow them and you can save money and time in your application process. However, if the Rules are not followed, the resultant circuit board design can challenge even the most sophisticated conformal coating system and its operator to achieve the finish desired.

Click Designing Circuit Boards for Selective Robotic Conformal Coating for further Rules.

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Designing for Selective Robotic Conformal Coating Processing: Rule 5 “Do not use a conformal coating as an underfill”

Under fills are used to fill the gap under components like flip chip components. The materials are specifically designed to match the coefficient of thermal expansion (CTE) of the device on the board so that any CTE change does not mean the component pops off the board or gets damaged.  Conformal coatings are not designed for this process and CTE mismatch can lead to severe damage of devices such as BGAs.

Rule 5

Do not specify the use of conformal coating as an under fill EVER. If a device needs to be under filled, specify a formulated under fill. Or, be prepared to find the component lifting off the PCB in the long term.

The Rules

The Rules for Selective Conformal Coating are straightforward. Follow them and you can save money and time in your application process. However, if the Rules are not followed, the resultant circuit board design can challenge even the most sophisticated conformal coating system and its operator to achieve the finish desired.

Click Designing Circuit Boards for Selective Robotic Conformal Coating for further Rules.

Designing for Selective Robotic Conformal Coating Processing: Rule 4 “Avoiding component Collisions”

As stated before robot systems are generally not intelligent unless you pay for very sophisticated software based systems with clever sensing systems. When a robot head drives a spray valve around it does not consider the variation in the component placement. It will continue “through” the component if it is in the way and probably destroy the PCB at the same time.

Rule 4

Understand that through-hole components have a very wide range of placement orientations, and if used on a PCB, the drawing must cover all possible orientations of the devices, plus 2.5mm optional coating area. This is to ensure you coat the component leads, wherever they may be positioned.

The Rules

The Rules for Selective Conformal Coating are straightforward. Follow them and you can save money and time in your application process. However, if the Rules are not followed, the resultant circuit board design can challenge even the most sophisticated conformal coating system and its operator to achieve the finish desired.

Click Designing Circuit Boards for Selective Robotic Conformal Coating for further Rules.

Designing for Selective Robotic Conformal Coating Processing: Rule 3 “Grouping Components”

Robot systems are generally not intelligent unless you pay for very sophisticated software based systems with clever sensing systems. All of these options cost money and time. To keep costs down consider that PCBs are 3D objects and considering the layout of the components and where you want conformal coating to be applied can save considerable problems.

Rule 3

Try and group all components of similar heights within the same general area of the assembly. This minimises the changes in dispensing height, enabling the machine to run efficiently at optimum speeds and give you the best coating coverage.

The Rules

The Rules for Selective Conformal Coating are straightforward. Follow them and you can save money and time in your application process. However, if the Rules are not followed, the resultant circuit board design can challenge even the most sophisticated conformal coating system and its operator to achieve the finish desired.

Click Designing Circuit Boards for Selective Robotic Conformal Coating for further Rules.

What types of valve are available for robotic selective conformal coating machines?

There are three main types of valves fitted to machines and used in conformal coating applications. These are:

  1. Airless Spray Valves commonly referred to in this industry as ‘film-coat’ valves.
  2. LVLP (Low Volume Low Pressure) Atomised spray valves).
  3. Dispense valves (Contactless or regular needle style)

To find out more about these valves click Choosing the Right Valve for a Selective Robotic Conformal Coating Application Process

Aeroqual solvent monitoring removes headache from Conformal coating process

Monitoring solvents with the Aeroqual range of Exposure Monitors affords early detection of the presence of unwanted and harmful solvent emissions in the workplace such as conformal coating fumes.

A range of options is available, to suit every requirement, from single workstation to multiple lines. SCH can offer help and support in ensuring you meet your health & safety obligations when using solvent based conformal coatings.

Solvent Exposure Monitoring and Testing

Aeroqual manufactures a wide variety of application specific gas sensors and sensor modules. These are all designed for use in ambient air and are capable of measuring a range of different gases.

Volatile Organic Compounds (VOC) Detection

The sensor can be used for a wide variety of volatile organic compounds including solventsand gases from conformal coatings with particular sensitivity toward oxygenated hydrocarbon compounds.

Click here for Aeroqual details.

 

Spray Conformal Coating successfully

Spraying Conformal Coating

SCH provide Technical Bulletins, training and FAQs on the full range of issues regarding conformal coating spraying.

The FAQs target issues such as how to spray PCBs with coating without ruining the board being spraying onto meeting ESD requirements and How to set up a conformal coating spray facility?

SCH also have a dedicated training room where techniques for conformal coating spraying can be taught.

Using this facility candidates get complete hands-on experience with the systems and processes without disturbance to production with a full range of systems available to ensure the best learning environment.

Conformal coating systems in the training facility include UV conformal coating curing, conformal coating dip, conformal coating spraying, manual conformal coating inspection and the new ACCIS Automated Conformal Coating Inspection System. Further, processes such as viscosity measurement, masking, de-masking, coating thickness measurement and solvent exposure monitoring can all be undertaken to give the maximum experience to the candidate.

Conformal coating spray application is one of the widest used methods in the electronics industry. Methods include conformal coating aerosols, spray booths and selective spray robots.

Conformal Coating Aerosols are suitable for very low volume application where invsetment in equipment is prohibitve. Conformal Coating Spray booths become economic when volume use of aerosols reach > 10 aerosols per month giving a return on investment relatively quickly. Selective spray robots may become cost effective where volume is high and detailed and compelx masking is required.

 Click for further information.