Design rules for dipping

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Design rules for circuits to be dip conformal coated are specialist guidelines
Dipping using conformal coating brings along its own specific rules and guidelines that can help save a lot of time, money and trouble on the production line.

Here are a list of rules and guidelines that could be considered.

  1. Design the board so the masking components are at one end
  2. Design to hold the board correctly
  3. Design the fixture correctly to avoid coating contamination
  4. Match the coating material to the dip process
  5. Design the board to drain to a corner
  6. Avoid using components that can hold conformal coating
  7. Use the correct components

 

Design the board so the masking components are at one end

If you can place connectors at one end of a circuit board then the dip process is truly the fasted method of application.

This technique is used a lot in automotive electronics.
 

Design to hold the board correctly

Ensure there is somewhere to hold or hook the PCBs during the dip process that allows the board to be suspended.

In conformal coating dipping the most critical factor is how to hold the circuit in the right orientation
In conformal coating dipping one of the most critical factors is how to hold the circuit in the right orientation for the dip process

PCBs ready to be dipped in conformal coating with a part allowing easy hanging

 PCBs ready to be dipped in conformal coating with a part allowing easy hanging

Design the fixture correctly to avoid coating contamination

If possible try and ensure the parts holding the board, whether it is a hook or fixture, do not get coated during the dip process to avoid cleaning the fixture.

When dipping a circuit board in conformal coating avoid the fixture coming into contact with the material itself. This adds another level of process with the cleaning of the fixture.
Avoid allowing the fixture to be contaminated with conformal coating. This adds another cleaning process to the production

The fixture is designed so that it never enters the conformal coating during dipping and cleaning is not required.
 

Match the coating material to the dip process

Try and avoid UV cure and moisture cure materials in standard dip coating systems.

If these materials are to be used, ensure that the dip coating system has suitable options and designs to handle the materials in the correct manner.

Also, ensure the staff are trained in the key issues relating to handling these coatings.
 

Design the board to drain to a corner

Design the circuit to allow it to be drained to a corner rather than an edge.

This can ensure less edge build up of conformal coating on the circuit board.

Draining of conformal coating dipped circuit boards
Ensure the conformal coating can drain easily from the circuit board to avoid excessive build up of thickness

 

Avoid using components that can hold conformal coating

Some components when dipped can capture coating in their shape.

If this happens then the coating will puddle and not drain away.

This can lead to problems of coating running off at a later stage or very thick coating leading to a problem with the coating integrity in the long term.
 

Use the correct components

Use the male header pin type connectors that can be masked easily with boots rather than the female sockets which cannot be easily.

Avoid using difficult to mask components or fit them after dip coating.

The challenge of masking them may be so high that the cost of processing is too much.

Male pin connectors makes conformal coating much easier due to the ease of masking with a masking boot

Male pin connectors makes conformal coating masking much easier due to the ease of masking with a masking boot

Do you know a Design Rule for dip conformal coating that could help others? Tell us now and we can add it to the list.

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