Nano-Copper Ink PTH Interconnect Low-Temperature Sintering
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Solution Overview
Problem
The wave soldering process for filling plated-through holes (PTH) in semiconductor manufacturing is inadequate due to high temperatures that can damage heat-sensitive components, difficulty in achieving full barrel filling without voids, especially in thicker boards and large components, and copper pad erosion.
Innovation Solution
The use of nano-copper ink dispersed in a solvent, applied using aerosol jet printers or SMT dispense machines, which is sintered at lower temperatures (below 200°C) to form reliable conductive interconnects, reducing copper pad erosion and achieving higher than 75% barrel filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wave soldering process is used to fill PTH, then copper interconnect can be formed, but high temperatures (235-245°C) damage heat-sensitive components
Solution Approach 1:
The patent changes the temperature parameter from traditional wave soldering (235-245°C) to low-temperature sintering (below 200°C). This is achieved by using nanoscale copper particles (1-100 nm) that can sinter at lower temperatures, thereby protecting heat-sensitive components while still forming reliable copper interconnects in PTH
2Manufacturing precision
If wave soldering process is used, then PTH filling can be achieved, but full barrel filling without voids is difficult due to heat sink effect
Solution Approach 1:
The patent uses nanoscale copper particles (1-100 nm) instead of bulk materials, which enable sintering at lower temperatures (below 200°C). This uniform low-temperature processing eliminates the heat sink effect problem that causes non-uniform temperature distribution and void formation in traditional wave soldering, achieving full barrel filling without voids
3Productivity
If wave soldering process is used, then PTH assembly can be completed, but copper pad erosion occurs
Solution Approach 1:
The patent reduces the processing temperature from 235-245°C to below 200°C by using nanoscale copper particles. This temperature reduction eliminates the thermal conditions that cause copper pad erosion while still achieving complete PTH assembly through low-temperature sintering of the nanoparticles
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 method enhances joint reliability, reduces component damage, and is more cost-effective by using copper instead of expensive metals, while minimizing copper pad erosion and achieving full barrel filling.
Implementation Method 1
the method further comprises sintering
Implementation Method 2
the removing the solvent comprises heating at a predetermined temperature
Data Source
AI summary
Methods of making a copper interconnect plated through hole assembly are disclosed. Nano copper ink dispersed in an organic solvent is able to be filled in the plated through hole and forming the copper interconnect by sintering at a temperature below the melting of the copper.