PCB Fixing Element Reduces Tolerance Demands in Press-Fit Assembly
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Solution Overview
Problem
The existing press-fit method for fastening printed circuit boards in acceleration sensor housings is prone to high accuracy and tolerance demands, leading to a significant number of rejects and increased production costs due to potential short circuits and mechanical misalignment.
Innovation Solution
A fixing element within the housing engages with the printed circuit board's outer boundary edge, providing additional mechanical stability and reducing tolerance requirements by using a ribbed projection that presses or cuts into the board's edge, allowing for improved alignment and support of the circuit board during insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the press-fit method is used to fasten the printed circuit board, then a solder-free electrical and mechanical connection is achieved, but very high accuracy and tolerance demands are required leading to increased rejects
Solution Approach 1:
The fastening function is segmented into two independent parts: electrical connection via press-fit pins and mechanical fixation via the fixing element. This segmentation allows each part to be optimized independently, reducing the tolerance burden on the press-fit zones while maintaining connection reliability.
Solution Approach 2:
The fixing element acts as an intermediary component that provides mechanical stabilization during the press-fit process. By engaging with the circuit board edge before and during insertion, it mediates the alignment between housing and board, reducing the precision demands on the press-fit zones.
2Stability of the object's composition
If four press-in zones are provided for mechanical attachment, then the printed circuit board is securely fastened, but the complexity of ensuring exact alignment of all connection pins increases
Solution Approach 1:
The mechanical fixation function is extracted from the press-fit zones and assigned to a dedicated fixing element. This removes the dual burden of electrical connection and mechanical fixation from the same components, simplifying the alignment requirements for the press-fit zones while maintaining mechanical stability.
Solution Approach 2:
Instead of using the press-fit pins for both electrical connection and mechanical support, the invention inverts the approach by using a separate fixing element for mechanical support and reserving the pins primarily for electrical connection. This inversion reduces the complexity of ensuring exact alignment.
3Reliability
If deviation of 1/10 mm occurs during insertion, then misalignment causes destruction of connection pins or short circuits, but such high precision requirements increase production costs
Solution Approach 1:
The fixing element provides beforehand cushioning by engaging with the circuit board edge prior to insertion and maintaining engagement during the process. This cushioning effect compensates for potential misalignments and prevents the harmful effects of 1/10 mm deviations, reducing rejects without increasing production costs.
Solution Approach 2:
The invention converts the potential harm of tolerance variations into a benefit by designing the fixing element to accommodate and correct minor misalignments. The frictional engagement mechanism transforms what would be destructive deviations into self-correcting alignment adjustments, reducing rejects while maintaining ease of manufacture.
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 solution reduces the need for precise alignment, decreases rejects, and enhances mechanical stability, thereby lowering production costs and preventing short circuits during the assembly process.
Implementation Method 1
which, when the printed circuit board is inserted into the housing, frictionally engages with an opposite outer boundary edge of the printed circuit board
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a fixing device and a method for fixing a printed circuit board (6) in a housing (4), wherein in order to produce a soldering-free electrical and mechanical connection between the housing (4) and the printed circuit board (6), during the insertion of the printed circuit board (6) into the housing (4), connecting pins (14) projecting beyond the housing (4) are pressed into plated-through openings (13) in the printed circuit board (6). According to the invention, for mechanical fixing and for compensating for tolerances, alongside two connecting pins (14) required for the electrical connection, a fixing element (44) integrally formed on the housing (4) in the interior of the housing is provided, which fixing element, during the insertion of the printed circuit board (6) into the housing (4), engages in a frictionally locking manner with an opposite outer boundary edge (34) of the printed circuit board (6).