Nickel-Rich Lead-Free Solder Paste for Oxide Layer Removal
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Solution Overview
Problem
The EU-wide ban on lead in soldering materials necessitates the development of a lead-free die- and clip-attach system that is as effective as high lead content systems, while existing solder pastes face challenges in removing oxide layers and require specific rheological properties for application and bonding.
Innovation Solution
A lead-free solder material comprising solder particles with at least 30 wt % nickel and an activator, such as organic acids or amines, which reacts with nickel oxide to facilitate bonding and reduce oxide layers, allowing for a 'no-clean' solder paste with reduced flux residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free solder material is used to comply with environmental regulations, then environmental compliance is improved, but bonding effectiveness and oxide layer removal capability deteriorate
Solution Approach 1:
The patent introduces an activator as an intermediary substance that facilitates the bonding process between nickel-based solder particles and metal surfaces. The activator specifically addresses oxide layer removal and surface activation, enabling reliable bonding with lead-free nickel-containing solder material while maintaining environmental compliance.
Solution Approach 2:
The patent modifies the chemical composition parameters of the solder material by incorporating nickel (at least 30 wt %) and specific activators (organic acids, amines, or their salts). These parameter changes enable the lead-free solder to achieve bonding effectiveness comparable to traditional lead-based systems.
2Object-affected harmful factors
If nickel-containing solder particles are used as lead-free alternative, then environmental compliance is improved, but oxide layer formation and removal difficulty increase
Solution Approach 1:
The activator is incorporated into the solder paste formulation in advance, performing preliminary chemical action on oxide layers before the actual bonding process. This preliminary activation and oxide removal action simplifies the manufacturing process by pre-conditioning the surfaces for optimal nickel solder bonding.
Solution Approach 2:
The activator serves as a chemical intermediary that reacts with nickel oxide layers, facilitating their removal or transformation into bondable surfaces. This intermediary action resolves the difficulty of oxide layer removal associated with nickel-containing solder materials.
3Ease of operation
If traditional flux systems are used with lead-free solder, then rheological properties for application are maintained, but flux residue and contamination increase
Solution Approach 1:
The patent modifies the flux composition parameters by selecting specific activators from organic acids, amines, or their salts with controlled concentrations. These parameter changes enable the flux to provide necessary rheological properties for screen printing and dispensing while minimizing harmful residue through controlled chemical activity and evaporability.
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 solution enables effective bonding without lead, reducing oxide layers and minimizing flux residue, thus meeting the performance standards of high lead content systems while adhering to environmental regulations.
Implementation Method 1
the activator is able to reduce (and thereby possibly remove) oxide layers from the surfaces to be joined by the solder (the bonding surfaces) and/or from the solder powder to allow good bonding
Implementation Method 2
heating at least the solder material to a melting temperature of the solder material
Data Source
AI summary
A lead-free solder material is provided. In one example, the solder material may include solder particles including at least 30 wt % nickel, and an activator including or consisting of at least one of a group of activator materials, the group including an organic acid or salt thereof, and an amine or salt thereof.