A Novel Bi₂O₃-TeO₂-B₂O₃-CuO Glass for Copper Metallization of Si₃N₄: Wettability, Thermal Stability, and Bonding Performance

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Interesting scientific contribution in the field of ceramic surface metallization using a glassy paste with copper dispersoids.

Author Response

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Reviewer 2 Report

Comments and Suggestions for Authors

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Reviewer 3 Report

Comments and Suggestions for Authors

  Authors have presented a Bi₂O₃ – TeO₂ – B₂O₃ – CuO glass system for applications at the surface metallization of Si3N4 ceramics. Glass system was investigated by varied method such as XRD, SEM, DSC, tensile testing, etc. The results are interesting and an optimal glass composition containing 20 mol % Bi₂O₃ was proposed.

A major revision is recommended to the authors, on the following points:

1. A general chemical formula of the glasses will be indicated.
2. The qualities of the Figures 4 and 7b) are not acceptable.
3. In the section 3.2 there are some incomplete sentences.
4. Figure 8 represents the effect L3 content on tensile strength and in the legend is written bond strength???Why?

Author Response

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Reviewer 4 Report

Comments and Suggestions for Authors

This manuscript discusses the development of a Bi2O3 – TeO2- B2O3-CuO glass system targeted for copper thick film metallization of silicon nitride ceramic substrates. The authors of this manuscript systematically investigate the influence of Bi2O3 content on thermal stability, wettability, microstructure, electrical resistivity, and bonding strength. The study also combines thermal analysis, wettability and mechanical studies to investigate the interfacial bonding mechanism. This topic is relevant to electronic packaging and ceramic metallization technologies, particularly for low-T processes on silicon nitride substrates. This work has sufficient experimental design, and the results are clearly presented. The authors claim that optimized glass composition improves wettability and adhesion while also maintaining electrical performance.  However, the discussion requires some more improvement before publication. Some of my comments are listed below.

1. Add some more information on the research gap and novelty of the work in the introduction part. Where exactly the research gap is addressed (composition optimization or interfacial mechanism, wettability enhancement or in terms of applications).
2. The author could have added some more information on possible interfacial reaction phases and any evidence on chemical bonding.
3. It would be better if the author adds XPS data. Because EDS mapping alone is not sufficient to confirm the reaction mechanisms.
4. Wettability needs more information. Has the authors performed any roughness profile using stylus profilometer or AFM study to see surface topography.
5. Reason for optimized wetting behavior at 750°C – justify?
6. What will be the CTE of substrate or without addition of Bi2O3. Stress mitigation by CTE requires more information and cite with references.
7. Figure captions should be self-explanatory. For example, Figure 7 caption.

Author Response

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Round 2

Reviewer 4 Report

Comments and Suggestions for Authors

Thank you for authors revision. I accept