Flowable Protective Compound for PCB Heat Sink Attachment
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Solution Overview
Problem
Existing electronic assemblies for transmission control modules face challenges in effectively dissipating heat and protecting components from mechanical and fluid loads, particularly in harsh environments like gear oil, while maintaining a compact design.
Innovation Solution
A printed circuit board with heat-generating components is covered by a flowable and curable protective compound, which also fills the gap between the board and a heat sink, adhering to both and providing a sealing and attachment mechanism, allowing for efficient heat dissipation and protection. The heat sink features a depression for stable contact and additional component placement on the second side of the board, reducing overall height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective cover is applied over heat-generating components, then components are protected from mechanical and fluid loads, but heat dissipation is impaired
Solution Approach 1:
The patent uses a thin, flowable protective compound that cures to form a protective layer. This compound can be applied as a liquid or paste that flows into all gaps and crevices, then hardens to provide mechanical protection while maintaining thermal conductivity pathways for heat dissipation.
Solution Approach 2:
The protective compound is designed as a composite material that combines protective properties (mechanical strength, fluid resistance) with thermal conductivity. This allows the same material to simultaneously protect components from gear oil and mechanical loads while enabling heat to pass through to the heat sink.
2Temperature
If a heat sink is placed in direct contact with the printed circuit board, then heat dissipation is maximized, but components on the second side of the board cannot be accessed and assembly height increases
Solution Approach 1:
The protective compound serves as an intermediary substance between the heat-generating components on the first side of the circuit board and the heat sink. It fills the gap and provides a thermally conductive pathway for heat to transfer from the components, through the compound, to the heat sink, while allowing the heat sink to be positioned closer to the board without direct contact.
Solution Approach 2:
The patent changes the physical state of the protective compound from liquid (flowable) to solid (cured) to achieve different functions at different stages. In liquid form, it flows into gaps and provides thermal contact; in cured form, it maintains structural integrity while preserving thermal pathways.
3Strength
If mechanical attachment methods are used to secure the heat sink, then attachment strength is ensured, but assembly complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces mechanical attachment methods (screws, clips, adhesives requiring separate application steps) with a flowable protective compound that is applied once and serves multiple functions. The compound is sprayed or poured over the components, flows into the gap, and upon curing, simultaneously provides protection and attachment to the heat sink.
Solution Approach 2:
The protective compound and attachment function are merged into a single material and application step. The same flowable compound that protects the components also serves as the attachment medium that bonds the heat sink to the circuit board assembly, eliminating the need for separate attachment components or steps.
4Length of stationary object
If the heat sink is positioned close to the printed circuit board, then assembly height is reduced, but heat-generating components cannot be adequately protected from gear oil
Solution Approach 1:
The protective compound acts as an intermediary barrier between the gear oil environment and the heat-generating components. It fills the gap between the heat sink and circuit board, creating a sealed environment that protects components from fluid infiltration while maintaining thermal pathways for heat dissipation.
Solution Approach 2:
The flowable protective compound forms a thin, conformal protective film over the components when cured. This film is thin enough to maintain compact assembly height but provides adequate protection against gear oil infiltration, combining protection functionality with space efficiency.
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 configuration effectively protects components from mechanical and fluid loads, enhances heat dissipation through a low thermal resistance path, and simplifies the attachment process, reducing the assembly's height and cost while maintaining reliability.
Implementation Method 1
the at least one gap is at least partially filled with the at least one flowable and curable protective compound in such a way that the flowable and curable protective compound is in direct contact with the circuit board and the heat sink and the heat sink in the cured state of the free-flowing and curable protective compound adheres to the protective compound in a cohesive manner
Implementation Method 2
the protective compound can support the dissipation of the heat generated by the components, for example via vias through the circuit board and in the direction of the heat sink
Data Source
Figure 1~4
Figure 5~7
AI summary
For an electronic assembly (1), in particular for a transmission control module, comprising a printed circuit board (2) having a first side (3) and a second side (4), which is averted from the first side (3), and having at least one heat-generating component (5) which is arranged on the first side (3) of the printed circuit board (2), wherein the electronic assembly (1) further comprises a heat sink (6) which has an inner face (7) facing the second side (4) of the printed circuit board (2), wherein the inner face (7) of the heat sink (6) is, at least in sections, spaced apart from the printed circuit board (2) by at least one gap (8), it is proposed that the at least one heat-generating component (5) is covered by a flowable and curable protective compound (9), and that the at least one gap (8) is at least partially filled with the at least one flowable and curable protective compound (9) in such a way that the flowable and curable protective compound (9) is in direct contact with the printed circuit board (2) and the heat sink (6), and the heat sink (6) adheres to the protective compound (9) in a cohesive manner when the flowable and curable protective compound (9) is in the cured state.