Board Connector Terminal Fitting Coplanarity and Resin Dregs
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Solution Overview
Problem
Existing board connectors face issues with resin dregs production and coplanarity due to the dimensions of terminal fittings and press-fit portions, leading to electrical troubles and inconsistent connections.
Innovation Solution
A board connector design featuring a tubular housing with a tab, press-fit portion, and lead portion, where the press-fit portion has an overlapping margin in the cross-section along the height direction to ensure coplanarity and prevent resin dregs, and the tab is inserted without overlapping margins to avoid scraping the inner surface, with chamfers and cuts to manage resin dregs effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the dimensions of the terminal fitting outer surface are made equal to the mounting hole inner surface dimensions, then the press-fitting margin is maximized, but resin dregs are produced due to scraping of the back wall by the tab
Solution Approach 1:
The terminal fitting is divided into three distinct portions: tab, press-fit portion, and lead portion. Each portion has different dimensional relationships with the mounting hole. The tab portion is designed without overlapping margin to avoid scraping, while the press-fit portion has overlapping margin for secure fixation, resolving the contradiction between press-fitting strength and resin dregs prevention.
2Object-generated harmful factors
If the dimensions of the terminal fitting outer surface are made smaller than the mounting hole inner surface dimensions, then resin dregs production is reduced, but the press-fitting margin is reduced
Solution Approach 1:
Different portions of the terminal fitting have different dimensional characteristics relative to the mounting hole. The tab portion has no overlapping margin (zero clearance) to prevent scraping, while the press-fit portion has overlapping margin (positive clearance) to ensure secure press-fitting. This local differentiation resolves the contradiction by applying different dimensional strategies to different functional regions.
3Ease of manufacture
If the position of the press-fit portion in the mounting hole is not determined, then the manufacturing process is simplified, but coplanarity cannot be ensured
Solution Approach 1:
The press-fit portion is designed with overlapping margin that protrudes beyond the mounting hole inner surface in the height direction. This preliminary design feature automatically determines the position of the press-fit portion and ensures coplanarity of the lead portion with the board surface, eliminating the need for additional position determination processes while maintaining manufacturing precision.
Data Source
AI summary
A board connector (10) has a tubular housing (20) that includes a back wall (25) with penetrating through holes (26). A terminal fitting (60) includes a tab (61) to be arranged to project into the housing (20) through the through hole (26), a press-fit portion (62) to be arranged inside the through hole (26) and a lead portion (63) to be arranged along a surface of a board (90). The press-fit portion (62) is inserted into the through hole (26) with an overlapping margin in a cross-section along a height direction in which the lead portion (63) faces the surface of the board (90). The tab (61) is inserted into the through hole (26) without any overlapping margin in the same cross-section.