PCB Terminal Recess for Solder Void Reduction
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Solution Overview
Problem
In electronic devices with printed circuit boards, air bubbles trapped in solder paste during the reflow process can lead to voids, compromising the connectivity between the electronic elements and the printed circuit board.
Innovation Solution
The design incorporates terminals with surface and insertion sections, where the surface section has a recess part aligned with the through hole, allowing air bubbles to escape during the reflow process, and optionally includes exhaust holes to further release gases, reducing void formation and enhancing connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface section is located over the through hole to restrict bubble movement, then the bubble movement is restricted, but voids are generated when bubbles remain in the solder paste
Solution Approach 1:
The surface section is divided into a flat part and a recess part, creating distinct functional zones. The recess part specifically addresses bubble management while the flat part maintains mechanical strength and electrical connection, resolving the contradiction between connection reliability and void formation.
Solution Approach 2:
Different portions of the surface section have different properties: the flat part provides structural support and electrical connection, while the recess part provides bubble release functionality. This local differentiation allows the single component to simultaneously achieve both connection reliability and reduced void formation.
2Reliability
If solder paste is applied in the through hole to couple the insertion section, then electrical connection is achieved, but air bubbles are trapped in the solder paste
Solution Approach 1:
The recess part acts as a dedicated bubble extraction zone, providing a specific pathway for trapped air bubbles to escape from the solder paste during reflow, while the rest of the structure maintains electrical connection functionality.
Solution Approach 2:
The recess part serves as an intermediary structure between the solder paste and the external environment, facilitating bubble release without compromising the electrical connection between the insertion section and the through hole.
3Object-affected harmful factors
If the surface sections are located on the upper-surface side to restrict bubble movement, then bubble movement is restricted, but the coupling certainty is reduced due to void formation
Solution Approach 1:
The surface section is segmented into functional zones where the recess part handles bubble management and the flat part ensures mechanical and electrical connection, allowing simultaneous achievement of bubble restriction and coupling certainty.
Solution Approach 2:
By giving different local properties to different parts of the surface section, the design allows the recess part to facilitate bubble release while the overall structure maintains coupling certainty, resolving the contradiction between bubble restriction and coupling reliability.
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 design effectively reduces the number of voids in the solder joints, improving the reliability and consistency of the connection between the electronic elements and the printed circuit board.
Implementation Method 1
air bubbles to escape during the reflow process
Implementation Method 2
The surface section is coupled with the surface land through the solder. The insertion section is disposed in the through hole and is coupled with the insertion land through the solder.
Data Source
AI summary
An electronic device includes a printed circuit board and an electronic element having a terminal. The terminal has a surface section and an insertion section. The printed circuit board includes a through hole extending from a first surface to a second surface of the printed circuit board, a surface land disposed on the first surface, and an insertion land integrally disposed on a sidewall of the through hole and on a periphery around the through hole. The surface section is coupled with the surface land through a solder. The insertion section is disposed in the through hole and is coupled with the insertion land through the solder. The surface section has a recess part and a portion of recess part is disposed so as to be axially aligned with a portion of the through hole.