PCB Casing Engagement Protrusion with Crushing Margin
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Solution Overview
Problem
Existing printed circuit board accommodation casings face issues with rattling due to gaps between the circuit board and the casing, and strengthening clamping pressure can lead to deflection, necessitating a more stable and secure holding mechanism.
Innovation Solution
The design incorporates a support surface and engagement protrusions with a crushing margin, where the support surface does not abut the printed circuit board, allowing the crushing margin to be effectively utilized to eliminate backlash and prevent deflection by releasing shavings into a gap, thereby stabilizing the board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the clamping pressure in the thickness direction is strengthened to suppress rattling of the printed circuit board, then the stability of the printed circuit board is improved, but the printed circuit board may be deflected
Solution Approach 1:
The engagement protrusion is positioned at a location where it engages the printed circuit board in the thickness direction (clamping direction) rather than only in the planar direction. This dimensional shift allows the protrusion to provide clamping force that suppresses rattling without requiring excessive planar clamping pressure that would cause deflection.
Solution Approach 2:
The engagement protrusion is specifically positioned at a location where the support surface does not abut on the printed circuit board, creating a localized engagement zone. This local quality differentiation allows the protrusion to engage the board edges without the support surface interfering, enabling effective clamping with minimal deflection risk.
2Reliability
If a crushing margin is set on the engagement protrusion to reliably hold the printed circuit board with clamping pressure, then the holding reliability is improved, but shavings may interfere with the support surface and cause deflection
Solution Approach 1:
The engagement protrusion is positioned at a location where the support surface does not abut on the printed circuit board, effectively extracting or separating the crushing function from the support function. This allows shavings generated by the crushing margin to be released without interfering with the support surface, eliminating the risk of deflection while maintaining holding reliability.
Solution Approach 2:
The casing structure is segmented into distinct functional zones: the support surface area and the engagement protrusion area. By positioning the protrusion where the support surface does not abut, the crushing function is separated from the support function, allowing independent optimization of each function without interference.
3Stability of the object's composition
If guide portions are provided on the inner wall surface to sandwich the printed circuit board, then the positional stability is improved, but gaps of tolerance may form between the board and inner wall surface
Solution Approach 1:
The engagement protrusion is designed to crush the crushing margin in advance during the insertion process, eliminating gaps of tolerance before the board is fully positioned. This preliminary action of crushing the margin pre-compresses the board against the guide portions, ensuring tight fit and eliminating rattling without requiring excessive final clamping pressure.
Data Source
AI summary
A printed circuit board accommodation casing includes: a support surface that abuts on a first planar portion of a printed circuit board; a side wall portion located outside in a planar direction of the printed circuit board, the first planar portion of which is abutted by the support surface; and an engagement protrusion formed on the side wall portion, in which a crushing margin, which is crushed against the first planar portion of the printed circuit board, is set on the engagement protrusion at a location where the support surface does not abut on the first planar portion of the printed circuit board.