Electronic Control Device Solder Connection Asymmetry
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Solution Overview
Problem
In electronic control devices for vehicles, the solder connections between chip components and wiring patterns are prone to cracking due to thermal expansion and contraction, leading to premature wire breakage and reduced reliability.
Innovation Solution
The electronic control device features wiring patterns with lands and wiring portions that are narrower than the chip component, with the connection points positioned outside the chip component's dimensions, allowing stress to be absorbed and crack progression to occur further away from the center, thereby increasing the distance to wire breakage and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the connection portion of land and wiring is disposed within the region where the chip component extends, then the stress applied to the solder can be absorbed by making the wiring narrower than the chip component, but a large stress is generated in both sides in the width direction of the solder connection portion, causing cracks to occur and reducing lifetime
Solution Approach 1:
The patent applies asymmetry by positioning the connection portion of the land and wiring at an asymmetric location relative to the chip component. Specifically, the connection portion is disposed outside the region where the chip component extends in the longitudinal direction, creating an uneven stress distribution that reduces stress concentration at the solder connection portion. This asymmetric positioning prevents cracks from occurring at both sides simultaneously, thereby improving solder connection reliability while maintaining stress absorption capability.
Solution Approach 2:
The patent moves the connection portion from a position within the chip component's longitudinal region to a position outside this region, effectively utilizing space in another dimensional arrangement. By disposing the connection portion outside the chip component's extension region, the design creates additional spatial buffer that reduces stress concentration on the solder, thereby preventing crack formation and improving reliability without compromising the stress absorption function.
2Stress or pressure
If the wiring width is made narrower than the chip component width, then stress can be absorbed, but the distance to the position where crack reaches the center is short, causing wire breakage to occur quickly
Solution Approach 1:
The patent employs asymmetry by positioning the connection portion outside the chip component's longitudinal extension region. This asymmetric arrangement creates an uneven stress distribution pattern where the stress is not concentrated at the center but distributed more favorably, extending the distance a crack must travel to reach the center. This increases the device lifetime by delaying wire breakage while maintaining effective stress absorption through the narrowed wiring design.
Solution Approach 2:
The patent applies preliminary action by pre-positioning the connection portion outside the chip component's extension region before any thermal cycling or stress occurs. This pre-positioning creates a built-in stress distribution pattern that inherently resists crack propagation from the outset, extending the time required for cracks to reach the center and cause wire breakage, thereby increasing device lifetime while maintaining stress absorption capability.
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 extends the lifetime of the device by delaying wire breakage and improving reliability by allowing the crack to propagate further before causing failure, reducing the stress on solder connections and preventing premature failure.
Implementation Method 1
solid wiring patterns and a chip component repeat expansion and shrinkage
Implementation Method 2
the stress applied to the solder can be absorbed by making the width of the wiring narrower than the width of the chip component soldered to the land
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
The objective of the present invention is to improve reliability in a solder connection portion between an electronic component and a wiring pattern. A pair of wiring patterns (31A and 31B) are formed on a circuit wiring board (30) with an insulation layer (37) therebetween. Each wiring pattern (31A and 31B) has a land (33a or 33b) and a wiring portion (34a or 34b) that is narrower than the land. By way of solder (42), a chip component (41) is soldered to the lands (33a and 33b). The x (width) direction center (Xa) of each connection portion (53) where a respective wiring portion (34a or 34b) is connected to a respective land (33a or 33b) is disposed at a position that is outside of both the region in which a region of predetermined width (Wc) of the chip component (41) extends in the x (longitudinal) direction, and the region in which a region of predetermined length (Lc) of the chip component (41) extends in a y (transverse) direction.