Frequently Asked Questions about Bubble-free Potting
How do bubbles form during the potting process?
There are two reasons why undesired air bubbles may form during potting:
- The potting material may not displace the air in the component at the desired spots
- Preparing and applying the potting material introduces air into the potting process
Why is it important to avoid air bubbles during potting?
Air bubbles that form when potting electronic components cause a range of problems that, depending on the quality requirements, usually cannot be tolerated or can result in component failure:
- Bubble expand under thermal load, resulting in stresses inside the workpiece. This compromises the component’s function and, in the worst case, leads to cracks in its outer layer.
- Air bubbles have poor thermal conductivity and thus increasingly impair the desired potting function.
- Air bubbles reduce the insulation quality and thus the high-voltage resistivity of the components.
- Air bubbles promote corrosion in components.
When is potting in a vacuum advisable?
In many applications air bubbles can be tolerated to a certain extent from a functional point of view. However, increasing numbers of electrical components have structural and quality requirements that demand completely bubble-free potting. This short checklist can help you determine when potting in a vacuum is appropriate:
- The spaces in the component to be potted are extremely small and atmospheric-pressure potting is not possible – #miniaturization
- The complex structure of the component (e.g. many undercuts) does not allow for bubble free atmospheric-pressure potting – #component design
- Sensitive electronics must be fully and reliably protected from outside influences (moisture, dirt, etc.) to guarantee sustainable product use – #functional quality, #high-performance applications
- Potting is part of component thermal management, which means that heat must be reliably dissipated – #functional quality, #high-performance applications, #reliability
- Potting should reduce thermal loads in the component – #functional quality, #reliability
- Potting should reduce a component’s fire risk – #safety, #high-performance applications
- Potting is used to protect electronic components from corrosion – #functional quality, #reliability
- Components should be potted if potting in a vacuum is increasingly becoming the standard for that component – #coiled products (stators, regulators, transformers), #high-voltage components (isolators), unprotected wire coils and enameled copper wires
- The potted electronics fulfill their safety functions – #safety, #reliability
If one or more of these points apply to your products, then they meet the potting requirements, so, if you have previously had bad experiences or if you clearly do not want to take any chances, then potting in a vacuum is the technology that will provide the desired results.
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