Self-Assembled Solder Bridge for Fine Pitch Semiconductor Mounting
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Solution Overview
Problem
Existing semiconductor mounting techniques, such as wire bonding, flip chip bonding, and tape automated bonding, face challenges including large mounting areas, increased time and effort for terminal connections, alignment difficulties, high costs due to expensive substrates, and compromised heat dissipation.
Innovation Solution
A novel fine pitch connection technique using a solder connector formed by self-assembly of solder particles in a bridge shape, connected between the semiconductor element's element electrode and the mounting board's electrode terminal, facilitated by a solder resin paste with a convection additive that promotes convection upon heating, allowing for self-aligned and self-assembled connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If wire bonding method is used to connect semiconductor chip electrodes to lead frame terminals, then electrical connection is achieved, but mounting area becomes large and connection time increases
Solution Approach 1:
The patent merges the semiconductor chip mounting and electrical connection processes into a single integrated step. The chip is mounted directly onto the substrate with its electrode-formed surface facing the substrate, and electrical connection is established simultaneously through bumps formed on the chip electrodes, eliminating the need for separate wire bonding operations.
Solution Approach 2:
The patent extracts and eliminates the intermediate lead frame component from the traditional wire bonding structure. By connecting the semiconductor chip directly to the substrate without a lead frame, the mounting area is reduced and the connection process is simplified.
2Area of stationary object
If flip chip bonding method is used with bumps on semiconductor chip, then direct mounting on substrate is achieved, but alignment becomes difficult due to narrow pitch
Solution Approach 1:
The patent applies preliminary action by pre-forming bumps on the semiconductor chip electrodes before mounting. These bumps serve as both connection elements and alignment references, enabling accurate positioning of the chip on the substrate even at narrow pitches.
3Reliability
If traditional wire bonding method is used, then electrical connection is established, but heat dissipation from semiconductor chip is compromised
Solution Approach 1:
The patent merges the electrical connection function and heat dissipation function into a single integrated structure. The bumps that provide electrical connection also serve as thermal conduction paths, directly transferring heat from the semiconductor chip to the substrate without the thermal resistance introduced by wire bonding.
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 the mounting area, simplifies the connection process, enhances alignment ease, lowers equipment costs, and improves heat dissipation while enabling fine pitch connections, offering a more efficient and cost-effective alternative to traditional methods.
Implementation Method 1
heating the solder resin paste so that the convection additive boils to cause convection in the resin, thus causing self-assembly of the solder powder contained in the solder resin paste to form a solder member that connects at least between the element electrode and the electrode pattern and between the electrode terminal and the electrode pattern
Implementation Method 2
the convection additive boils to cause convection in the resin
Implementation Method 3
causing self-assembly of the solder powder contained in the solder resin paste to form a solder member that connects at least between the element electrode and the electrode pattern
Data Source
AI summary
A mounted body (100) of the present invention includes: a semiconductor element (10) having a surface (10a) on which element electrodes (12) are formed and a rear surface (10b) opposing the surface (10a); and a mounting board (30) on which wiring patterns (35) each having an electrode terminal (32) are formed. The rear surface (10b) of the semiconductor element (10) is in contact with the mounting board (30), and the element electrodes (12) of the semiconductor element (10) are connected electrically to the electrode terminals (32) of the wiring pattern (35) formed on the mounting board (30) via solder connectors (20) formed of solder particles assembled into a bridge shape. With this configuration, fine pitch connection between the element electrodes of the semiconductor element and the electrode terminals of the mounting board becomes possible.