Protruding External Connection Conductor for Module Stress Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing modules with external connection conductors face reliability issues due to stress concentration at the interface between the conductors and solder balls, leading to potential cracking or rupture under external or internal stresses like heat, caused by the fragile intermetallic compounds formed at these interfaces.
Innovation Solution
The module design features an external connection conductor with a projection extending along the surface of the resin layer, allowing the second end to protrude and distribute stress, reducing the overlap of mechanically weak interfaces with stress-concentrated areas, and includes a supporting and covering section configuration to enhance connection reliability, with the covering section formed by plating and the supporting section made of a pin-shaped conductor for cost-effective manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the second end face of the external connection conductor and the surface of the resin layer are flush with each other, then the manufacturing process is simplified, but the connection reliability deteriorates due to stress concentration at the interface between the conductor and solder
Solution Approach 1:
The external connection conductor is designed to protrude from the resin layer surface, transitioning from a flush (2D plane) configuration to a protruding (3D spatial) configuration. This dimensional change separates the conductor's second end from the resin layer surface plane, creating a stepped structure that eliminates stress concentration at the interface while maintaining manufacturing feasibility through standard PCB drilling and plating processes
Solution Approach 2:
The protruding portion of the external connection conductor acts as an intermediary element between the resin layer and the solder ball. This intermediate structure distributes mechanical stress away from the fragile intermetallic compound interface, providing a mechanical bridge that enhances connection reliability without complicating the manufacturing process
2Reliability
If the external connection conductor protrudes through the resin layer surface, then the connection reliability is improved by reducing stress concentration, but the manufacturing precision requirements increase
Solution Approach 1:
The external connection conductor is pre-formed with the required protrusion length and positioning during the PCB manufacturing process, before soldering takes place. The conductor is drilled, plated, and formed to the correct dimensions in advance, ensuring precise positioning and eliminating the need for post-assembly adjustments, thereby maintaining high manufacturing precision while achieving improved connection reliability
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 enhances the reliability of external connections by reducing stress on interfaces and increasing the connection area, preventing stress concentration and improving mechanical strength, thus providing a high degree of reliability and cost-effectiveness.
Implementation Method 1
the covering section formed by plating and the supporting section made of a pin-shaped conductor
Data Source
AI summary
A module includes a circuit board, a resin layer, an external connection conductor, a solder bump. The resin layer is disposed on a first principal surface of the circuit board. The external connection conductor is arranged in the resin layer, has a first end connected to the circuit board and a second end protruding through the surface of the resin layer and includes a projection extending along the surface of the resin layer in a portion that protrudes through the surface of the resin layer. The solder bump is disposed on the second end of the external connection conductor.