Solder Protruded Electrodes for Semiconductor Bump Height Control
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Solution Overview
Problem
Semiconductor devices with micro bumps face challenges in soldering due to height variations, leading to defective connections and poor soldering characteristics, especially when the bumps are close and the receiving land on the mounting board is small, resulting in inadequate heat transfer and solder deformation.
Innovation Solution
The semiconductor device features solder protruded electrodes with a plate-like shape extending from underlying electrodes, containing a predetermined quantity of solder that increases in height during reflow heating to ensure contact with the mounting board, thereby stabilizing the solder connection and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solder bumps are formed by plating process, then solder protruded electrodes can be formed on underlying electrodes, but height variation of bumps increases leading to defective soldering
Solution Approach 1:
The patent applies a preliminary action by forming a solder resist film with openings before the plating process. This preliminary structure defines the exact area where solder will be deposited, ensuring that even with plating variations, the solder remains confined to the correct region and maintains proper height relative to the underlying electrode, thereby reducing height variation and defective soldering
Solution Approach 2:
The patent changes the parameter of solder volume by controlling the opening area of the solder resist film. By adjusting the opening size, the amount of solder deposited is controlled, which directly affects the final bump height. This parameter control ensures consistent bump heights across all solder joints, resolving the height variation problem inherent in plating processes
2Volume of moving object
If micro bumps are used with narrow pitch, then device size is reduced, but soldering quality deteriorates due to inadequate heat transfer
Solution Approach 1:
The patent applies local quality by creating solder bumps with controlled local volume through the solder resist film openings. Each bump is formed with a specific amount of solder material localized to the opening area, ensuring adequate heat transfer capacity for each individual bump even when pitch is narrow. This local control of solder quantity maintains reliable soldering while preserving the compact device size achieved through micro bump usage
3Adaptability or versatility
If solder bump height varies, then manufacturing flexibility is improved, but soldering reliability deteriorates due to poor contact with mounting board
Solution Approach 1:
The solder resist film with pre-defined openings serves as a preliminary action that controls solder deposition. This preliminary structure ensures that solder is deposited only within the opening boundaries, creating bumps with consistent height and shape. The opening design allows flexibility in determining bump dimensions while maintaining uniformity across all bumps, thus achieving both adaptability and reliability
Solution Approach 2:
The patent uses parameter changes by controlling the opening dimensions of the solder resist film to achieve desired bump heights. By adjusting the opening size and shape, different bump configurations can be achieved (providing adaptability), while the controlled deposition process ensures consistent height across all bumps (maintaining reliability). This parameter control resolves the contradiction between flexibility and uniformity
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 solution effectively suppresses defective soldering by ensuring the solder protruded electrodes contact the mounting board, improving the yield of solder connections and allowing for easier cleaning and under-fill resin sealing, while allowing for adjustable bump height and pitch without widening the array distance.
Implementation Method 1
when the solder is melted by reflow heating
Implementation Method 2
reflow heating is performed to process the solder bumps 52 to be spherical
Data Source
AI summary
The present invention provides a semiconductor device that can suppresses poor connection caused by the variation of the heights of bumps during reflow heating, can be applied to a narrow array pitch, and can freely adjust the heights of the bumps.