Low-Temperature Pressure Sintering in Low-Oxygen Atmospheres
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Solution Overview
Problem
Low-temperature pressure sintering processes face challenges in preventing oxidation of metal surfaces during the sintering of electronic subassemblies, as existing protective measures like Ni-flash Au or Ni-Pd coatings are costly and incomplete, and the process itself accelerates oxidation due to heating.
Innovation Solution
The process involves conducting low-temperature pressure sintering in a controlled low-oxygen atmosphere with an oxygen content between 0.005 and 0.3%, using a gastight chamber and an oxygen-containing material that releases oxygen under pressure to maintain a minimal oxygen concentration, and employing a separating film like Teflon to prevent oxidation, along with a sintering temperature of 230-300°C and pressure of 20-40 MPa.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If low-temperature pressure sintering is performed to join electronic components, then joining strength is improved, but oxidation of metal surfaces accelerates due to heating
Solution Approach 1:
The patent applies an inert atmosphere (nitrogen or other inert gas) during the low-temperature pressure sintering process to prevent oxidation of metal surfaces. The inert gas environment replaces oxygen, eliminating the harmful oxidation effect while allowing the sintering process to proceed at low temperatures to achieve strong joining without compromising metal surface integrity.
2Reliability
If precious metal coatings (Ni-flash Au or Ni-Pd) are applied to protect against oxidation, then oxidation resistance is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent extracts and eliminates the need for precious metal protective coatings by performing the sintering process in an inert atmosphere. This removes the additional manufacturing steps and materials required for coating application, while still achieving oxidation protection through the controlled gas environment, thereby reducing both cost and manufacturing complexity.
3Reliability
If precious metal coatings are applied to prevent oxidation, then oxidation resistance is improved, but the ability to perform multi-stage sintering operations is reduced
Solution Approach 1:
By maintaining an inert atmosphere throughout the entire multi-stage sintering process, the patent enables multiple sintering operations to be performed sequentially without oxidation concerns. The inert environment protects metal surfaces during each stage, allowing complex multi-stage processes to be executed successfully without requiring protective coatings that would limit process flexibility.
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 effectively prevents oxidation of metal surfaces, allowing for durable and reliable sintered connections while reducing costs and cycle time, enabling successful two-stage sintering operations and maintaining the integrity of electronic subassemblies.
Implementation Method 1
an oxygen-containing material which releases oxygen under pressure, such that, in the course of the sintering operation, the aforementioned minimum oxygen concentration in the process atmosphere can be achieved directly at the sintering location by the application of pressure and temperature
Implementation Method 2
the heating up of the components and circuit carriers to be joined not only accelerates the diffusion of the joining material introduced, e.g. silver (Ag), into the connecting metals of the parts to be joined
Implementation Method 3
but also assists the oxidation of metallic surfaces. Thus, for example, the oxidation of copper (Cu) begins visibly to proceed more quickly at 80° C. than at room temperature
Data Source
AI summary
Process for producing an electronic subassembly by low-temperature pressure sintering, comprising the following steps: arranging an electronic component on a circuit carrier having a conductor track, connecting the electronic component to the circuit carrier by the low-temperature pressure sintering of a joining material which connects the electronic component to the circuit carrier, characterized in that, to avoid the oxidation of the electronic component or of the conductor track, the low-temperature pressure sintering is carried out in a low-oxygen atmosphere having a relative oxygen content of 0.005 to 0.3%.