Semiconductor Solder Joint Strength via Outer Electrode Area
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Solution Overview
Problem
Lead-free solder materials used in surface mount semiconductor devices reduce the bonding strength between solder balls and electrode portions, with prolonged melting times exacerbating this issue by increasing interface breaks and reducing joint integrity.
Innovation Solution
The semiconductor device design features solder balls made of tin and silver, with electrode portions on the outer periphery larger than those on the inner periphery, allowing for quicker cooling and alloy formation, enhancing interface strength through selective suppression of alloy components and improved heat dissipation using cooling gas or a heat sink plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-free solder materials are used, then environmental compliance is improved, but bonding strength between solder balls and electrode portions deteriorates
Solution Approach 1:
The patent applies different area sizes to different electrode portions based on their location. Outer periphery electrode portions are made larger than inner periphery electrode portions, creating local quality differences that optimize cooling efficiency and bonding strength for each region while maintaining overall device performance with lead-free solder materials
Solution Approach 2:
The patent introduces a new dimension of control by varying the area of electrode portions in the planar direction. This dimensional change allows for differentiated thermal management and bonding optimization without changing the solder material composition or adding complex external cooling systems
2Manufacturing precision
If melting time is prolonged, then solder balls are thoroughly melted and bonded, but bonding strength reduces due to increased interface breaks
Solution Approach 1:
The patent creates local quality differences in thermal dissipation by varying electrode portion areas. Outer electrode portions with larger areas provide enhanced cooling that shortens melting time and prevents interface breaks, while inner electrode portions maintain adequate melting characteristics
Solution Approach 2:
The patent changes the physical parameter of electrode portion area to control thermal dissipation rate. By adjusting this parameter spatially, the patent optimizes both melting completeness and bonding strength, achieving short melting times without interface breaks
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 increases the bonding strength and thermal shock resistance of solder balls, preventing falls and strength deterioration, while maintaining effective connection and thermal management in semiconductor devices.
Implementation Method 1
the electrode portions on the outer periphery are formed larger than the electrode portion on the inner periphery, and the plurality of ball electrodes are solder balls heated and melted on the electrode portions on the underside of the board so as to form an alloy on the interfaces, the solder balls containing tin and silver but not containing lead. The electrode portions under the solder balls on the outer periphery (that is, the electrode portions on the outer periphery) are formed larger than those on the inner periphery, thereby achieving effective cooling.
Implementation Method 2
the plurality of ball electrodes are solder balls heated and melted on the electrode portions on the underside of the board so as to form an alloy on the interfaces
Implementation Method 3
heated and melted the solder balls to form an alloy on the surfaces of the electrode portions
Data Source
AI summary
A semiconductor device of the present invention includes a circuit board having a number of electrode portions on the front side and the underside, an electronic circuit element such as a semiconductor chip bonded to the electrode portions on the front side of the circuit board and composing an electronic circuit; and a plurality of ball electrodes for external connection, the ball electrodes being formed on the electrode portions on the underside of the circuit board. Of the electrode portions on the underside of the circuit board, an electrode portion on the outer periphery is formed larger than an electrode portion on the inner periphery. The plurality of ball electrodes are solder balls heated and melted on the electrode portions on the underside of the board so as to form an alloy on the interfaces, the solder balls containing tin and silver but not containing lead.