Solder Bump Formation Using Molded Resin Composition
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Solution Overview
Problem
Conventional methods for forming solder bumps on semiconductor devices and wiring boards are complex and costly, making it difficult to achieve high-density mounting with uniform bump height and reliable connections.
Innovation Solution
A method involving a flat plate with projections or recesses is used to align with electronic components, where a resin composition with solder powder is annealed to self-assemble and form uniform solder bumps with pits or projections, allowing for controlled height and uniform shape formation, and subsequent fitting and connection without melting, enabling low-temperature mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional solder bump formation method is used, then solder bumps can be formed, but the bumps are limited to hemispherical shape and pitch reduction is difficult
Solution Approach 1:
The patent changes the physical state parameters of solder material by using powder form instead of liquid or solid ingot, and controls temperature parameters during formation to achieve non-hemispherical shapes. This enables pyramid and other customized shapes that improve mounting density
Solution Approach 2:
The patent performs preliminary shaping of solder bumps before mounting by forming them in molds with specific geometries (pyramid, cube, etc.). This preliminary action allows the bumps to fit precisely into corresponding recesses on the substrate, enabling higher pitch reduction
2Reliability
If metal bumps with conducting adhesive are used, then connections can be formed, but pitch reduction and mounting density improvement are insufficient
Solution Approach 1:
The patent extracts and eliminates the conducting adhesive layer from the connection structure by using pure solder bumps. The solder material itself provides both the mechanical connection and electrical conductivity, simplifying the structure and enabling smaller pitch
Solution Approach 2:
The patent uses composite solder material composition including base metal particles, alloying elements, and optional additives to achieve both mechanical strength and electrical conductivity in a single material system, eliminating the need for separate adhesive layers
3Productivity
If complex fabrication processes are used for high density mounting, then mounting density can be improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent segments the fabrication process into independent stages: solder powder preparation, mold filling, sintering/formation, and mounting. Each stage can be optimized separately and performed with simple equipment, reducing overall process complexity while achieving high density
Solution Approach 2:
The patent uses mold copies to replicate precise bump geometries. Simple mold cavities are copied onto multiple solder bumps simultaneously, enabling high precision shapes without complex fabrication processes
4Reliability
If uniform bump height is required for reliable connections, then connection reliability improves, but process control complexity increases
Solution Approach 1:
The patent performs preliminary height control during the bump formation stage by using molds with precise depth control and controlled sintering/compaction processes. This preliminary action ensures uniform height before mounting, eliminating the need for complex post-formation control
Solution Approach 2:
The patent enables self-leveling and self-densification of solder powder during the formation process through controlled heating and pressing. The material itself achieves uniform density and height without requiring complex external control mechanisms
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 allows for high-density, reliable semiconductor mounting with uniform solder bumps, simplifying the fabrication process and reducing costs while ensuring high connection strength and precision.
Implementation Method 1
forming solder bumps on the terminals by melting the solder powder included in the resin composition through annealing of the resin composition
Implementation Method 2
allowing the melted solder powder to self-assemble on the terminals for growing the melted solder powder up to a level of a surface of the flat plate
Implementation Method 3
after cooling and solidifying the solder bumps
Data Source
AI summary
A method for forming solder bumps for realizing high density mounting and a highly reliable method for mounting a semiconductor device is provided. A flat plate having a plurality of projections or recesses thereon is prepared; the flat plate is aligned to oppose an electronic component and a resin composition including a solder powder is supplied to a gap between the flat plate and the electronic component; the resin composition is annealed to melt the solder powder included in the resin composition for growing the solder powder up to the level of the surface of the flat plate by allowing the melted solder powder to self-assemble on terminals, so as to form solder bumps on the terminals; and the flat plate is removed after cooling and solidifying the solder bumps. Thus, the solder bumps having pits corresponding to the projections or having protrusions corresponding to the recesses are formed.