In-Vehicle Control Housing Screw Structure for PCB Waterproof Mounting
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Solution Overview
Problem
Existing in-vehicle control devices face challenges in achieving both waterproofness and robustness of the circuit board fixing structure while maintaining circuit board flatness, especially with the use of ball grid array packages, due to insufficient fixing structures.
Innovation Solution
The control device incorporates a base made of a steel plate material with a U-shaped cylindrical portion and screw portion, using male or female screws to fasten the circuit board, ensuring a secure and watertight connection without requiring additional adhesive seals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the circuit board is simply fixed to the base with a clip, then the assembly is easy to manufacture, but the fixing structure lacks robustness and waterproofness
Solution Approach 1:
The base is segmented into a plate-shaped main body portion and a bottomed cylinder with U-shaped cross section that protrudes from the main body. This segmentation allows the cylinder to provide enhanced fastening functionality while the main body maintains structural support, resolving the contradiction between simple manufacturing and robust fixing.
Solution Approach 2:
The fixing structure transitions from a simple planar clip attachment to a three-dimensional configuration where the bottomed cylinder protrudes from the base surface. The screw portion on the cylinder's peripheral surface enables multi-point fastening, significantly improving robustness while maintaining manufacturing feasibility through standard fastening components.
2Reliability
If the circuit board is firmly fixed to the base, then the fixing robustness is improved, but circuit board warpage may occur
Solution Approach 1:
The fastening force is locally concentrated at the screw portion of the bottomed cylinder rather than being distributed across the entire circuit board surface. This localized fastening approach secures the circuit board firmly at critical points while minimizing overall stress and preventing warpage, thus resolving the contradiction between fixing robustness and board flatness.
3Reliability
If additional adhesive seals are used to achieve waterproofness, then the waterproof performance is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The bottomed cylinder with screw portion creates a self-sealing fastening structure where the threaded connection itself provides the waterproof seal. The interlocking screw threads and cylinder wall form a tight seal without requiring additional adhesive seals or gaskets, thus achieving waterproofness while reducing device complexity and manufacturing cost.
Data Source
AI summary
Provided is an in-vehicle control device (1) including: a base (10); a cover (20) fixed to the base; a circuit board (30) housed in the base and the cover; and an electronic component (40) mounted on the circuit board, in which the base is made of a steel plate material, and includes a plate-shaped main body portion (13), a bottomed cylinder (14) having a U-shaped cross section in which one of front and back surfaces of the main body portion is recessed and protrudes to the other side, and a screw portion (15) provided on a peripheral surface of the cylinder, and the circuit board is fastened to the base by a fastening member (6, 7) screwed into the screw portion of the cylinder.