Circuit Board Pad Layout for Warpage-Resistant Solder Joints
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Solution Overview
Problem
Heat concentration in corner regions of semiconductor devices causes warpage of the substrate, leading to solder bridging and degraded connection performance between the semiconductor device and the circuit board, affecting reliability.
Innovation Solution
The design of the circuit board includes larger first conductive pads in the corner zones and smaller second conductive pads in the center and other zones, with wider solder-ball portions for the second pads to reduce solder bridging, and the method involves optimizing the layout and soldering process to ensure proper alignment and spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform conductive pads are used in all regions of the circuit board, then manufacturing is simple, but heat concentration in corner regions causes solder bridging and connection degradation
Solution Approach 1:
The patent applies local quality by differentiating conductive pad sizes based on location: larger first conductive pads are placed in corner zones where heat concentration occurs, while smaller second conductive pads are used in central zones. This local differentiation addresses the heat-induced solder bridging problem in corners without unnecessarily complicating the entire board design.
Solution Approach 2:
The circuit board is segmented into different zones (corner zones and central zones) with different pad configurations. This segmentation allows targeted solutions for heat concentration problems in specific regions while maintaining simpler designs in other regions, resolving the contradiction between reliability and complexity.
2Reliability
If larger conductive pads are used in corner zones to prevent solder bridging, then connection reliability improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the parameter of conductive pad size based on location. By increasing pad size in corner zones, the design provides larger tolerance margins for solder joint formation, which actually reduces the effective precision requirements compared to using uniformly small pads that leave no margin for error in heat-affected regions.
3Object-generated harmful factors
If smaller conductive pads are used in central zones, then solder bridging is reduced, but connection strength may be compromised
Solution Approach 1:
The patent applies local quality by using smaller conductive pads specifically in central zones where heat concentration and solder bridging risks are lower. This localized approach maintains adequate connection strength in central regions while effectively preventing solder bridging, resolving the contradiction between preventing harmful factors and maintaining strength.
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 configuration reduces solder bridging and improves the connection performance between the semiconductor device and the circuit board, enhancing the reliability of the semiconductor assembly.
Implementation Method 1
The first conductive pads are respectively soldered to one part of the solder joints through a plurality of first solder-ball portions. The second conductive pads are respectively soldered to another part of the solder joints through a plurality of second solder-ball portions.
Data Source
AI summary
An electric device includes a semiconductor assembly, a circuit board, first conductive pads and second conductive pads. The circuit board has a chip-mounted area with a rectangular shape. The first conductive pads are arranged in a center zone or all corner zones of the chip-mounted area, and the second conductive pads are arranged within the rest in the chip-mounted area. The first conductive pads are respectively soldered to one part of solder joints of the semiconductor assembly through first solder-ball portions, and the second conductive pads are respectively soldered to another part of the solder joints of the semiconductor assembly through second solder-ball portions. Each of the second conductive pads is sized smaller than one of the first conductive pads, and a maximum width of each of the second solder-ball portions is greater than a maximum width of each of the first solder-ball portions.