Semiconductor Flip-Chip Solder Bridge Prevention
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Solution Overview
Problem
The miniaturization and increased accuracy of semiconductor devices lead to narrower bump pitches, increasing the likelihood of solder bridge failures due to adjacent pads being connected by solder in flip chip mounting.
Innovation Solution
A semiconductor device manufacturing method involving a tetragonal frame-shaped array of electrode pads on the semiconductor element and corresponding elongated connection pads on the wiring substrate, with electrode terminals formed such that their axis is separated from the center of the solder bulge on the connection pads, reducing the likelihood of solder bridges by altering the solder joint formation during the reflow process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flip chip mounting is implemented to electrically connect electrode terminals directly to pads, then electrical connection reliability is improved, but solder bridge failures occur due to narrow bump pitch
Solution Approach 1:
The connection pads are designed with asymmetric dimensions where the length in the bump layout direction is smaller than the width in the orthogonal direction. This asymmetric geometry, combined with the offset positioning of electrode terminals from pad centers, creates non-uniform solder distribution that prevents solder bridges while maintaining reliable electrical connections.
Solution Approach 2:
The electrode terminals are pre-positioned with their axes offset from the centers of the connection pads in the bump layout direction before soldering. This preliminary asymmetric positioning guides the solder flow during reflow to accumulate on one side of each pad, preventing solder from bridging to adjacent pads.
2Area of moving object
If miniaturization is implemented to reduce semiconductor chip size, then device density is improved, but bump pitch is narrowed increasing solder bridge risk
Solution Approach 1:
The connection pads exhibit local quality variation through asymmetric dimensions and offset terminal positioning. The pad geometry is specifically tailored in different directions: shorter in the bump layout direction to reduce solder bridge risk, and wider in the orthogonal direction to ensure adequate solder volume and connection reliability.
Solution Approach 2:
The pad geometry parameters are changed from conventional symmetric designs to asymmetric configurations. The length-to-width ratio is optimized with length < width, and the terminal-to-pad center offset distance is carefully controlled to achieve optimal solder distribution that prevents bridging while maintaining connection integrity.
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 method reduces defects caused by solder short-circuits between adjacent connection pads by controlling the movement and distribution of solder, ensuring reliable electrical connections and improved semiconductor device reliability.
Implementation Method 1
applying a solder including a bulging central portion on an upper surface of each of the connection pads, forming a plurality of pillar-shaped electrode terminals respectively on the plurality of electrode pads
Data Source
AI summary
A method for manufacturing a semiconductor device includes preparing a semiconductor element including electrode pads laid out along the periphery of the semiconductor element in a tetragonal frame-shaped array to form a line of electrode pads along each side of the semiconductor element, preparing a wiring substrate including connection pads corresponding to the electrode pads, applying solder including a bulging central portion on an upper surface of each connection pad, forming pillar-shaped electrode terminals on the electrode pads so that each electrode terminal has an axis separated from a peak of the bulging central portion of the solder on the corresponding connection pad in a longitudinal direction of the corresponding connection pad, and electrically connecting the electrode terminals with the solder to the connection pad.