Terminal Pin Protrusion Design for Bubble-Free PCB Soldering
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Solution Overview
Problem
Existing printed circuit board joining techniques using terminal pins and soldering often result in bubbles forming near the protruding portions, which can lead to cracking under vibration and affect conductivity due to insufficient solder filling.
Innovation Solution
A printed circuit board unit design featuring a terminal pin with a protruding portion that includes a projection surface and a recess surface, providing a sufficient clearance for molten solder to fill the through hole, preventing bubble retention and ensuring reliable conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a protruding portion is added to the terminal pin to prevent it from falling before soldering, then the terminal pin can stand upright in the through hole, but the protruding portion may cause insufficient solder filling and bubble formation
Solution Approach 1:
The protruding portion is designed with differentiated local qualities: a projection surface that abuts the second inner surface to provide stability, and a recess surface that creates clearance for solder filling. This local differentiation resolves the contradiction by making different parts of the protruding portion serve different functions - one for stability, another for reliable soldering
Solution Approach 2:
The protruding portion extends in the thickness direction beyond the printed circuit board thickness, creating an additional dimensional space. This extra dimension provides the clearance between the recess surface and the first inner surface, allowing solder to flow properly while the projection surface maintains stability
2Stability of the object's composition
If the protruding portion abuts both inner surfaces of the through hole, then the terminal pin is securely positioned, but the solder cannot be sufficiently filled around the protruding portion
Solution Approach 1:
The protruding portion has different surface characteristics at different locations: the projection surface abuts the second inner surface for positioning stability, while the recess surface maintains clearance from the first inner surface to allow solder filling. This local quality differentiation resolves the contradiction between secure positioning and proper solder filling
3Productivity
If bubbles remain in the solder near the protruding portion, then the soldering process is completed quickly, but the solder joint becomes weak and may crack under vibration
Solution Approach 1:
The recess surface is designed in advance to create clearance space before soldering occurs. This preliminary structural design ensures that molten solder has adequate space to flow and fill the through hole completely, preventing bubble formation and ensuring strong, vibration-resistant solder joints
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
The design ensures complete solder filling, preventing bubble retention and enhancing the reliability of the electrical connection between the terminal pin and the printed circuit board, even under vibrational stress.
Implementation Method 1
the molten solder is sufficiently filled into the through hole through the clearance between the recess surface of the protruding portion and the first inner surface of the through hole
Data Source
AI summary
A printed circuit board unit includes: a printed circuit board including a through hole including first and second inner surfaces opposite to each other; a terminal pin including an insertion portion inserted into the through hole; solder filled into the through hole, and joining the printed circuit board with the terminal pin, wherein the insertion portion includes a base portion abutting the first inner surface, and a protruding portion including: a projection surface projecting from the base portion to the second inner surface and abutting the second inner surface; and a recess surface located at a rear side of the projection surface and spaced apart from the first inner surface, and a length of the protruding portion in a thickness direction of the printed circuit board is greater than a thickness of the printed circuit board.