Gold Electrode Connection Structure for Narrow-Pitch Package Reliability
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Solution Overview
Problem
The challenge of securing conduction reliability and insulation reliability in semiconductor packages with narrow pitch connections, particularly due to thermal stress and alloy formation during high-temperature soldering, is exacerbated by the brittleness of tin-bismuth solder and the incompatibility of materials with different thermal expansion coefficients.
Innovation Solution
A connection structure utilizing gold electrodes connected by a bonding portion comprising a tin-gold alloy as the primary region and a bismuth-containing region as a reinforcing portion, with an intermediate layer of an anisotropically conductive film containing uniformly spaced solder particles, ensuring high melting point and crack resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional connection structures (screw connections, welding, bonding) are used to connect the battery module housing to the battery pack housing, then the battery pack can be assembled, but production costs increase and production time is extended
Solution Approach 1:
The connection structure is segmented into a first connection portion integrated with the battery module housing and a second connection portion integrated with the battery pack housing. This segmentation allows each portion to be independently formed on respective components and then connected through a simplified connection process, reducing overall assembly complexity and time
Solution Approach 2:
The connection portions are merged with their respective housings through integral formation (e.g., injection molding), creating a unified structure that eliminates separate connection components. This merging reduces the number of parts and simplifies the assembly process while maintaining connection functionality
2Ease of manufacture
If conventional connection structures (screw connections, welding, bonding) are used to connect the battery module housing to the battery pack housing, then the battery pack can be assembled, but manufacturing costs increase
Solution Approach 1:
The connection structure is divided into first and second connection portions that can be independently manufactured and then assembled. This segmentation enables parallel production of connection components and housings, reducing manufacturing lead time and cost while simplifying the overall manufacturing process
Solution Approach 2:
The connection portions are designed to self-align and connect through their geometric features (e.g., protrusions and recesses, snap-fit mechanisms) without requiring external fastening operations. This self-service capability eliminates the need for additional screws, welds, or bonds, reducing both manufacturing cost and process complexity
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
A connection structure including: a first circuit member having a plurality of first electrodes; a second circuit member having a plurality of second electrodes; and an intermediate layer having a plurality of bonding portions electrically connecting the first electrodes and the second electrodes, in which at least one of the first electrode and the second electrode that are connected by the bonding portion is a gold electrode, and 90% or more of the plurality of bonding portions include a first region containing a tin-gold alloy and connecting the first electrode and the second electrode and a second region containing bismuth and being in contact with the first region.