PCB Opening Under MLCCs to Prevent Heat Buildup and Charring
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Solution Overview
Problem
Multilayer ceramic capacitors (MLCCs) used in automotive EMC filtering can malfunction, leading to heat generation and potential fires due to leakage currents, which pose a safety risk as they can cause the printed circuit board to char and combust.
Innovation Solution
A circuit design featuring a printed circuit board with an opening in the region of the MLCC projection, which prevents heat accumulation and reduces the risk of ignition, with the opening being elongated parallel to the MLCC contact rows and having dimensions that are at least 20% to 50% of the MLCC projection, and created using curved or parallel boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an MLCC is mounted directly on the printed circuit board, then the electrical connection is reliable and compact, but heat accumulates between the MLCC and the board causing charring and fire hazards
Solution Approach 1:
The patent extracts the harmful heat accumulation zone by creating an opening in the printed circuit board directly beneath the MLCC. This removes the problematic interaction between the MLCC and the board material, allowing heat to dissipate rather than accumulate, while preserving the electrical connection through the opening edges or surrounding structure.
Solution Approach 2:
The opening is created in advance during board manufacturing, before the MLCC is mounted. This preliminary structural modification prevents heat accumulation from occurring in the first place, rather than attempting to mitigate it after the fact. The anti-action is built into the board design itself.
2Object-affected harmful factors
If the printed circuit board has an opening under the MLCC, then heat accumulation is prevented and fire safety is improved, but the structural integrity and current carrying capacity of the board may be reduced
Solution Approach 1:
The opening is localized specifically beneath the MLCC footprint, rather than being a general reduction in board material. This concentrates the safety improvement where it is most needed (directly under the heat-generating component) while minimizing the impact on overall board strength. The surrounding board structure remains intact to maintain structural integrity.
Solution Approach 2:
The opening covers only the necessary area beneath the MLCC, which is partial action - enough to prevent heat accumulation but not so extensive as to compromise board strength. The dimensions are optimized to provide sufficient safety margin without excessive material removal.
3Object-affected harmful factors
If the opening is large enough to prevent heat accumulation effectively, then fire safety is improved, but the layout complexity and manufacturing difficulty increase
Solution Approach 1:
The opening is created during the standard PCB manufacturing process, before component mounting. This preliminary action integrates the safety feature into the base manufacturing workflow rather than requiring separate post-processing steps, maintaining ease of manufacture while achieving effective heat dissipation.
Solution Approach 2:
The opening is designed as a simple geometric shape (rectangular, circular, or oval) that can be easily defined by standard PCB routing tools. This segmentation into a basic shape makes the manufacturing process straightforward and compatible with existing fabrication capabilities.
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
This design effectively prevents charring and flame propagation on the printed circuit board, ensuring safety by maintaining the circuit's layout integrity and preventing current flow through the board, thus limiting damage to the MLCC and other components.
Implementation Method 1
it essentially prevents heat from accumulating between the MLCC and the printed circuit board
Implementation Method 2
leakage current 38 will occur, which does not trigger any protection measures but power consumption increases and heat is generated
Data Source
AI summary
A circuit having a printed circuit board and at least one multilayer ceramic capacitor (MLCC) is described, characterized in that the printed circuit board has at least one opening in the region of the projection of the MLCC on the printed circuit board. The opening is not filled with any material and in the event of the MLCC malfunctioning it essentially prevents heat from accumulating between the MLCC and the printed circuit board.