Circuit Board Terminal Layout to Prevent Reflow Tilting
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Solution Overview
Problem
Circuit boards with unused terminals can tilt during reflow soldering due to the absence of connection pins on these terminals, disrupting the stability and alignment of the circuit board when connected to another board.
Innovation Solution
A circuit board design where connection pins are provided on at least some terminals, with drive terminals disposed in a point-symmetric manner across four divided areas on the board's lower face, ensuring balanced support and stability even with unused terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If connection pins are provided on all connection terminals, then the circuit board stability is improved, but the manufacturing cost and complexity increase
Solution Approach 1:
The connection terminals are segmented into two categories: drive terminals (which receive connection pins) and function terminals (which may not receive connection pins). This segmentation allows the circuit board to have selective pin provision, improving stability where needed while reducing complexity and cost where functions are optional or unused.
Solution Approach 2:
Instead of providing connection pins on all terminals (excessive action), the invention applies partial action by providing pins only on drive terminals that are always used, while omitting pins on function terminals that may remain unused. This reduces overall complexity while maintaining necessary stability.
2Ease of manufacture
If connection pins are omitted on unused terminals, then the manufacturing cost is reduced, but the circuit board may tilt during connection
Solution Approach 1:
The invention uses asymmetric placement of drive terminals within each divided area, positioned non-uniformly relative to the area center. This asymmetric arrangement, when combined with the four-area division, creates an overall balanced distribution of drive terminals across the circuit board, ensuring stable alignment during reflow soldering even when some function terminals lack connection pins.
Solution Approach 2:
The drive terminals in opposite divided areas are positioned to balance each other, creating a counterweight effect. The non-uniform but point-symmetric arrangement ensures that the gravitational and thermal forces during soldering are evenly distributed, preventing tilting even with selective pin omission.
3Stability of the object's composition
If drive terminals are arranged in a point-symmetric manner, then the circuit board tilt is prevented, but the design complexity increases
Solution Approach 1:
The circuit board lower face is divided into four distinct areas, with drive terminals arranged in a point-symmetric manner across these areas. This segmentation approach simplifies the design process by providing a structured framework for terminal placement, making it easier to achieve balanced distribution while preventing tilt.
Solution Approach 2:
The point-symmetric arrangement of drive terminals creates a balanced, equipotential distribution of support points across the circuit board. This symmetric configuration ensures that thermal and mechanical stresses are evenly distributed during soldering, achieving tilt prevention through a systematic design pattern that is actually simpler to implement than arbitrary asymmetric arrangements.
Data Source
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Figure 3
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AI summary
In a circuit board (1) installed with a semiconductor module on an upper face and provided with connection terminals (14) on a lower face, a connection pin is provided on at least some of the connection terminals (14). The connection terminals (14) include a drive terminal (14D) for driving the semiconductor module and a function terminal (14F) for connecting the semiconductor module and other function units. The disposition of the drive terminal (14D) in each of divided areas (D1 to D4) is point-symmetric with respect to a center (O) of the circuit board (1), the divided areas (D1 to D4) being the circuit board (1) divided into four.