PCB Potting Container Gaps for Thermal Stress Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The use of potting compounds in field devices for explosion-endangered regions poses challenges due to volume changes with temperature, leading to potential cracks and failure to maintain the required minimum covering for EX-qualification.
Innovation Solution
A circuit board design featuring a potting compound container with gaps in the convex edge regions of the potting compound cover, which suppresses capillary action and prevents the potting compound from migrating, thereby ensuring a consistent minimum covering even with temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a potting compound container is filled completely with potting compound to ensure adequate covering, then the minimum covering for EX-qualification is maintained, but volume changes with temperature cause cracks and force the potting compound to migrate
Solution Approach 1:
The patent introduces gaps specifically at convex edge regions of the potting compound container cover, creating localized variations in the container structure. These gaps are positioned only where capillary forces are strongest (at convex edges), allowing the potting compound to be contained adequately in most areas while providing relief zones at critical locations where temperature-induced volume changes occur.
Solution Approach 2:
The gaps are pre-positioned in the container design to counteract the capillary forces that would otherwise cause the potting compound to migrate toward the cover. By anticipating the direction and mechanism of potential migration (via capillary action at convex edges), the design preemptively blocks this harmful effect while maintaining adequate covering elsewhere.
2Reliability
If an intermediate space is kept free between the potting compound container and filled potting compound to accommodate volume changes, then crack formation is prevented, but capillary forces cause the potting compound to climb the side walls and occupy the intermediate space
Solution Approach 1:
The patent introduces gaps specifically at convex edge regions of the potting compound container cover, creating localized variations in the container structure. These gaps are positioned only where capillary forces are strongest (at convex edges), allowing the potting compound to be contained adequately in most areas while providing relief zones at critical locations where temperature-induced volume changes occur.
Solution Approach 2:
The patent converts the harmful capillary effect into a controlled feature by introducing gaps at convex edges. These gaps allow the potting compound to safely terminate before reaching the cover, transforming the potential harm of capillary migration into a predictable design feature that actually helps define the boundary of the potting compound and ensures adequate covering in the central region.
3Ease of manufacture
If the potting compound container is designed without gaps to maintain structural integrity, then manufacturing is simpler, but capillary forces cause migration and cracks form during temperature changes
Solution Approach 1:
The patent introduces gaps specifically at convex edge regions of the potting compound container cover, creating localized variations in the container structure. These gaps are positioned only where capillary forces are strongest (at convex edges), allowing the potting compound to be contained adequately in most areas while providing relief zones at critical locations where temperature-induced volume changes occur.
Solution Approach 2:
The patent introduces asymmetry into the otherwise symmetric potting compound container by creating gaps specifically at convex edge regions. This asymmetric feature targets the specific locations where capillary forces are strongest, providing effective resistance to migration while maintaining structural integrity and simplicity in the overall container design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively maintains the necessary minimum covering for EX-qualification, preventing cracks and ensuring the reliability and safety of field devices in explosive environments by managing volume changes and capillary forces.
Implementation Method 1
Disadvantageous in the use of a potting compound is that such changes its volume as a function of temperature. In the case of a decrease of temperature, the potting compound shrinks and in the case of an increase of temperature, the potting compound expands.
Implementation Method 2
When an intermediate space between the potting compound container and the filled potting compound is kept free, it can, however, occur that the potting compound because of capillary forces climbs the side walls of the potting compound container in the direction of the potting compound cover
Data Source
AI summary
Circuit board for a field device of automation technology comprising a plurality of electronic components (4) and a potting compound container (2) made of a plastic and having a peripheral side wall defining an outer contour of the potting compound container, a potting compound cover adjoining the side wall and an opening located on the potting compound cover far side, wherein the potting compound container is set via the opening over at least a part of the plurality of electronic components (4) and filled with a potting compound in such a manner that electronic components covered by the potting compound have a predetermined, or defined, minimum covering, wherein the potting compound container is, however, not completely filled with potting compound and wherein in the potting compound cover in an edge region, which borders a transition from the side wall to the potting compound cover, at least one gap is present, which extends at least over a convex edge region of the outer contour.