Tag Archive | design rules

What information do I need to provide to get a conformal coating quotation for subcontract service?

When deciding to look at outsourcing your conformal coating process there are fundamental questions you need to answer and information to be provided to allow us to provide an accurate quote.

Questions to be answered include:

  1. Do you require the circuit boards to be cleaned or is this a no clean process?
  2. What are your expected volumes of PCBs to be processed?
  3. What turnaround time do you require on the service?
  4. What conformal coating material do you want applied?
  5. Do you have photos and /or masking drawings of the PCBs?
  6. How big are the PCBs for costing purposes?
  7. Do you have a particular coating process you prefer to be used?
  8. Do you have any masking requirements before coating application?
  9. What conformal coating standards do you require the PCBs to be inspected to?
  10. Are there any materials on the PCB such as silicone RTV that can cause problems when processing?
  11. Are there any special requirements?

These are the basic questions and each of them will lead to further questions. As with many projects, many answers are unknown and SCH can help develop the conformal coating process with you.

Take a look at our conformal coating services introduction to understand what we can offer you.

Or, contact us here at +44 1226 249019 or email sales@schservices.com

 

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Designing for Selective Robotic Conformal Coating Processing: Rule 13 “Sticking coatings to non stick silicones is a pain”

Applying silicone RTVs to circuit boards to provide support to components for long term reliability is fine. Just don’t do it before you apply a conformal coating to the surface unless the conformal coating itself is a silicone. Acrylic and urethane coatings do not stick to silicone. So, don’t try unless you want defects appearing.

Rule 13

If you call out silicone staking materials for ruggedisation purposes, use a silicone conformal coating. If you don’t want to use a silicone conformal coating, then use a urethane or epoxy staking compound.

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 12 “Coating 3D components is hard work. Why do it?”

When a circuit board surface looks like a scene from a cityscape and is highly 3D in nature, choosing to coat the sides of components is a really difficult process. You will need at least 5 axes of rotation, the process will slow down, quality really goes down and it looks awful cosmetically. If you don’t need it, don’t do it.

Rule 12

Make coating component packages optional.  Coating the sides of a 3D device is difficult, especially since the coating is subject to gravity, as well as de-wetting due to mould release agents used in the component fabrication.  The plastic or metal package mouldings are almost certainly more resistant to humidity or other forms of water than any conformal coating.

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 11 “Why do you want to coat the edge of a circuit board”

Conformal coating works by protecting the components and stopping conduction through leakage between leads and devices. Most of the time the edge of the circuit board does not need to be coated. So, why specify that it should be?

Rule 11

Make coating the edge of a PCB optional – it is tricky and messy, especially if there is no frame or breakout around the board, and is of questionable efficacy in improving coating or reliability performance.

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 10 “Treat connectors with respect!”

Conformal coating and connectors are the ultimate problem for processing with a spray valve or gun. Any coating close to a connector could wick (suck up into) a connector very easily and ruin the component. Therefore, a strategy for handling coating around connectors is required.

Rule 10

Use conformal coating gel around connectors if you want to get close to the connector with the material.  Conformal coating materials will flow freely into unsealed connectors and wick up connector leads.

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 9 “A flat board is a happy conformal coating process”

Many printed circuit boards can become warped in the manufacturing process. Or, they can bend in the conformal coating process if not adequately supported. This means that the surface is not even for the valves to travel across. For processes where the valves are running very close to the surface of the board this can be critical and lead to defects.

Rule 9

The board should be flat and sufficiently rigid to prevent sagging during dispensing or curing, otherwise coatings may flow and pool in unexpected fashions.  In particular, heavy boards may need to be palletized to provide sufficient rigidity.

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 8 “Biscuit layout can be critical. Get it right”

When laying out multiple PCB biscuit designs , this can be a real source of problems and make the process very inefficient.

Rule 8

When coating multiple PCBs in a biscuit configuration, ensure you seek input from production engineers regarding orientation to optimise robot path and valve operation. Having to stop and start often and/or change dispense height reduces your throughput massively and the coating can be deposited poorly.

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.