Silyl-Protected Solder Paste for Stable Storage and Bonding
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Solution Overview
Problem
Existing solder pastes for surface mount components on circuit boards face deterioration in physical properties during storage and soldering due to the reaction of carboxyl groups with solder powders, leading to reduced aggregating properties, wettability, and increased viscosity.
Innovation Solution
A solder paste containing solder powder and a flux component with a compound having a carboxyl group protected by a trialkylsilyl group, which remains inert during storage and hydrolyzes to form carboxyl groups upon heating, effectively removing oxide films and maintaining physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional flux component containing free carboxyl groups is used, then the solder paste shows good initial wettability and aggregating properties, but the physical properties deteriorate during storage due to reaction with solder powder
Solution Approach 1:
The carboxyl groups are pre-protected by silylating them before storage. This preliminary action prevents the harmful reaction between carboxyl groups and solder powder during storage, while allowing the carboxyl groups to become active when needed during soldering through hydrolysis.
Solution Approach 2:
A silylating agent is introduced as an intermediary substance that temporarily protects the carboxyl groups by forming silyl esters. This intermediary compound prevents direct reaction between carboxyl groups and solder powder, while being convertible back to active carboxyl groups under soldering conditions.
2Reliability
If the carboxyl groups are kept active to ensure good wettability, then bonding performance is improved, but viscosity increases and aggregating properties deteriorate during storage
Solution Approach 1:
The carboxyl groups are pre-protected by silylation before storage to maintain stable physical properties. Upon heating during soldering, the silyl esters hydrolyze to regenerate active carboxyl groups, ensuring good wettability and bonding performance without compromising storage stability.
Solution Approach 2:
The chemical state of the carboxyl groups is changed from active (prone to reaction) to protected (stable) form for storage, then reverted back to active form during soldering through hydrolysis. This parameter change allows optimization of both storage stability and bonding performance at different stages.
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
The solder paste maintains excellent physical properties during storage and ensures low connection resistance and good bonding between components, improving conductivity and storage stability.
Implementation Method 1
a flux component containing a compound having at least one carboxyl group protected by a trialkylsilyl group
Implementation Method 2
effectively removing oxide films and maintaining physical properties
Implementation Method 3
an electrode of the electronic component and an electrode of the board are bonded by a solder bonding portion formed using the solder paste
Data Source
AI summary
A solder paste includes a solder powder; and a flux component containing a compound having at least one carboxyl group protected by a trialkylsilyl group.