Joining Sheet With Segmented Solder And Thermosetting Layers
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Solution Overview
Problem
Conventional solder joining methods using tin-bismuth based solder pastes with thermosetting resins face issues such as active agent deactivation and require advanced printing technologies, leading to low shock resistance and reliability, especially with the miniaturization of electronic components.
Innovation Solution
A joining sheet comprising a solder layer with solder particles, a thermoplastic resin, and an active agent, along with a thermosetting resin-containing layer laminated on its surface, where the active agent and thermosetting resin are in separate layers to prevent deactivation, ensuring excellent solder melting and reinforcement of the solder joining portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermosetting resin and active agent are mixed in the same solder paste, then the solder joining portion is reinforced by curing, but the active agent is deactivated by reaction with thermosetting resin, resulting in insufficient solder melting
Solution Approach 1:
The solder paste is divided into two separate layers: a solder particle-containing layer with the active agent, and a thermosetting resin-containing layer. This segmentation prevents the active agent from reacting with the thermosetting resin before heating, ensuring the active agent remains effective for solder melting while the thermosetting resin provides reinforcement after curing.
Solution Approach 2:
The thermosetting resin layer is prepared in advance and positioned adjacent to the solder particles layer, but the curing reaction is delayed until after the solder melting process. This preliminary preparation allows the system to be ready for both solder melting and subsequent reinforcement without the active agent being deactivated prematurely.
2Manufacturing precision
If screen printing is used to apply solder paste to miniaturized terminals, then solder joining can be achieved, but advanced printing technology is required and industrial burden increases
Solution Approach 1:
The solder paste is segmented into two functional layers that can be applied separately or as a integrated structure. This segmentation allows for alternative application methods that do not require precise screen printing, such as placement of pre-formed layered structures, thereby reducing the need for advanced printing technology while maintaining manufacturing precision for miniaturized terminals.
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 approach enhances solder joining reliability and strength by maintaining active agent effectiveness and eliminating the need for advanced printing technologies, enabling efficient formation of solder joints with improved shock resistance and reduced industrial burden.
Implementation Method 1
an active agent capable of activating the solder particles
Implementation Method 2
a thermosetting resin-containing layer which is laminated on at least one surface in a thickness direction of the solder layer and contains a thermosetting resin
Implementation Method 3
heating the laminate at a temperature that is not less than the melting point of solder particles
Data Source
AI summary
A joining sheet includes a solder layer which contains solder particles, a thermoplastic resin, and an active agent capable of activating the solder particles and a thermosetting resin-containing layer which is laminated on at least one surface in a thickness direction of the solder layer and contains a thermosetting resin.