The Performance Characterization of a Drop-on-Demand Inkjet-Printed Gold Film Under the Temperature Conditions for Airborne Equipment

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript describes the validation of a conductive inkjet printed gold layer for avionic applications. The manuscript is relatively well written and the experimentation is carried out with acceptable rigor. In my opinion, however, the current form of the manuscript presents a limited level of novelty. The authors use a commercial gold nanoparticles dispersion, they print it using a single set of printing conditions and anneal the resulting layers at a fixed temperature. I understand that the novelty here is testing the properties of the conductive gold layer according to avionics standards, but a minimum exploration of different printing conditions is, in my opinion, required. Exploring the effect of different film thicknesses (number of printing layers), different annealing temperatures and others on the final properties is required in order to provide a meaningful overview.

In addition, the main issues that I can detect are:

1) The manuscript is full of “Error! Reference source not found”. Please revise.

2) Figure 1 is quite messy. I suggest reorganizing it.

3) Figure 2 (the SEM characterization of the Au layer) is mislabeled as figure 1. In addition, these are results and should be moved to the results section and properly discussed there.

4) Lines 108-109: these results should be reported in the present manuscript. Please wait and report the results of the ongoing characterization.

5) What is the thickness of the films? Providing the micrography of a section would be helpful.

6) The authors report values of resistance, but what is the sheet resistance of the layers?

7) What is the reproducibility of the experiments carried out? How many samples were characterized?

Author Response

Dear reviewer. Thank you very much for your time and effort in reviewing our work. Please find below the answer to your inquiries. 

1) The manuscript is full of “Error! Reference source not found”. Please revise.
This has been fixed. It looks like there was an issue when referencing figures and table after we uploaded the original document. This issue has been fixed.

2) Figure 1 is quite messy. I suggest reorganizing it.
Figure 1 shows the workflow for the fabrication and evaluation of the device. The authors decided to provide a better caption to explain each step of the process instead.

3) Figure 2 (the SEM characterization of the Au layer) is mislabeled as figure 1. In addition, these are results and should be moved to the results section and properly discussed there.
The figure numbering has been fixed. With respect to moving the figure to the results section, the authors believe that the results section should focus on analyzing the device response to the different airborne environmental categories. The SEM image merely shows that the sintering process was performed successfully.

4) Lines 108-109: these results should be reported in the present manuscript. Please wait and report the results of the ongoing characterization.
Those results at part of a different project, therefore they are not included here.

5) What is the thickness of the films? Providing the micrography of a section would be helpful.
The authors mentioned that the gold film was fabricated by printing 3 layers on functional ink. There are abundant number of papers that report the thickness of 3 layered films fabricated using functional inks with nano particles.
Since this study focuses on evaluating the device response after a typical drop on demand device fabrication routine, the authors do not aim to characterize the film. Instead, the authors aimed to perform functional tests. 

6) The authors report values of resistance, but what is the sheet resistance of the layers?
The resistance is provided at different temperatures in order to compute the TCR. 

7) What is the reproducibility of the experiments carried out? How many samples were characterized?
The reproducibility is demonstrated after 3 tests. every test shows the same starting condition. Also, Figure 7 shows the behavior of the sample after 2.9 hours. 

The standard used calls for different tests and one of them is a 10-hour test with no need of repetition. 
The variance is a function of time.

 

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

In this manuscript, the performance of a film on a ceramic substrate manufactured using gold (Au) NPs manufactured with the Drop-on-Demand methodology for avionics applications is evaluated. The results showed that the Au films printed on an Alumina substrate successfully resisted the environmental temperature procedure for airborne equipment. This work is meaningful for the development of avionics industry. However, the manuscript is not well written. The novelty of this research including the sceneries is unclear. This paper is thus not recommended for publication in this journal.

The authors need to pay attention to the following issues:

1.The novelty of this manuscript is not clearly described in section Introduction. It is suggested that authors clarify the knowledge gap and the novelty of the paper.

2.What are the temperature values for stages T4 and T5 in Table 4? It is suggested that the authors add the temperature values for stages T4 and T5 in Figure 5.

3.In section 4, it is recommended to supplement the in-depth analysis of the results.

4.In Figure 9, why is the temperature testing range for TCR selected as 18-85 ℃?

5.The introduction mentions that utilizing high thermal budget materials such as alumina ceramic as a substrate would make it possible to sinter conductive material at high enough temperatures to achieve thermomechanical stability of the film. In this study, how is the mechanical stability of the inkjet-printed Au film? It is suggested to add relevant characterization and analysis.

6.The manuscript is sloppily written. It is recommended that the authors conduct a thorough review before the next submission. Some problems about academic standards exist in the manuscript, such as (not limited): The manuscript fails to reference the figures and tables, resulting in errors. The font size in figures should be kept as consistent as possible. The fitting formula in Figure 9 has the writing error.

Comments on the Quality of English Language

English Language needs to be improved.

Author Response

The authors would like to thank the reviewer for recommendations provided. 
Please find the comments to below.

1.The novelty of this manuscript is not clearly described in section Introduction. It is suggested that authors clarify the knowledge gap and the novelty of the paper.
The novelty of this work was added and shown in page 1 line 70.

2.What are the temperature values for stages T4 and T5 in Table 4? It is suggested that the authors add the temperature values for stages T4 and T5 in Figure 5.
The table was wrong and incomplete. The table corrected was updated. 

3.In section 4, it is recommended to supplement the in-depth analysis of the results.
The authors added.
Section 4 is meant to show the results obtained from the environmental characterization of the sample. The authors provided more details to explain the results obtained.

4.In Figure 9, why is the temperature testing range for TCR selected as 18-85 ℃?
Because that is the temperature range provided by the avionics standard.

5.The introduction mentions that utilizing high thermal budget materials such as alumina ceramic as a substrate would make it possible to sinter conductive material at high enough temperatures to achieve thermomechanical stability of the film. In this study, how is the mechanical stability of the inkjet-printed Au film? It is suggested to add relevant characterization and analysis.
The goal of the paper was not to check the stability of the substrate. 
It is accepted practice to use such substrate. The goal was to study the gold film manufactured using the drop-on-demand method.

6.The manuscript is sloppily written. It is recommended that the authors conduct a thorough review before the next submission. Some problems about academic standards exist in the manuscript, such as (not limited): The manuscript fails to reference the figures and tables, resulting in errors. The font size in figures should be kept as consistent as possible. The fitting formula in Figure 9 has the writing error.
We welcome this input, and each paragraph was meticulously checked. 

 

 

Reviewer 3 Report

Comments and Suggestions for Authors

In this work, the functional inks that contain nanoparticles (NPs) were used to 3D print electronic materials on different substrates, which have the most promising application in the aerospace industry due to the capability of the method to fabricate custom low weight geometry films. The experimental results show that the Au films printed on an alumina substrate successfully resisted the environmental temperature procedure for airborne equipment. The manuscript could be published on the Journal after a minor revision.

1. Please polish the language, such as “Furthermore, The” should be “Furthermore, the”.

2. The key words should add the “Au film”

3. The key word of “Gold nano particles” should be “Gold nano particles ink”.

4. “Drop- on-Demand” should be “Drop- on-Demand inkjet print”.

5. “Error! Reference source not found” should be found to revise into right format.

6. Please provide the characterization of Gold nano particles ink.

7. The conclusion should be extracted and purified into one paragraph.

8. Please add some related literatures about inkjet printing metal film structures. Sensors and Actuators: A. Physical 2023, 351, 114161.

Author Response

The authors would like to thank the reviewer for their suggestions. 

1. Please polish the language, such as “Furthermore, The” should be “Furthermore, the”.
   The document was polished per the recommendation.
   
   
   
2. The key words should add the “Au film”
   Gold film added as a key word
3. The key word of “Gold nano particles” should be “Gold nano particles ink”.
   “Gold nano particles ink” added as a key word
4. “Drop- on-Demand” should be “Drop- on-Demand inkjet print”.
   “Drop- on-Demand” changed to “Drop- on-Demand inkjet print”
   
   
5. “Error! Reference source not found” should be found to revise into right format.
   “Error! Reference source not found” fixed
   
   
6. Please provide the characterization of Gold nano particles ink.
   The gold nano particles ink is a commercial product, and the information is widely available. The authors added the specifications (Novacentrix JG-125).
   
   
7. The conclusion should be extracted and purified into one paragraph.
   The conclusions aimed to explain the physical factors that contributed in the results section.
   
   
   
8. Please add some related literatures about inkjet printing metal film structures. Sensors and Actuators: A. Physical 2023, 351, 114161.
   The reference has been added.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Unfortunately, the way the authors addressed my observations is unsatisfactory. The study carried out is too limited, and the relationship between the processing conditions of the gold layers and the performances observed is totally missing. The authors simply prepared a gold layer using a standardized set of processing conditions, without providing any insight of how processing conditions affect performances. Then, they verified that said layer can be used in the context of airborne equipment production. This approach makes the study incomplete. In general, the study presents a limited set of experimental results.

In detail, for the different points:

3) I do not agree. The SEM is fundamental to show the morphology obtained. It is a result.

4) The results regarding how microstructure changes affect temperature-dependent resistance measurements should be included here, in order to provide some insight.

5) The answer provided here is a nonsense. Final thickness depends on the type of ink employed, on the printer used, on annealing conditions,… Consequently, the answer “There are abundant number of papers that report the thickness of 3 layered films fabricated using functional inks with nano particles” is totally unacceptable. The authors must directly measure the thickness of their layers.

Author Response

3) I do not agree. The SEM is fundamental to show the morphology obtained. It is a result.
SEM images taken prior test are now shown in the document.

4) The results regarding how microstructure changes affect temperature-dependent resistance measurements should be included here, in order to provide some insight.
No noticeable effects were seen based on prior vs after SEM images.

5) The answer provided here is a nonsense. Final thickness depends on the type of ink employed, on the printer used, on annealing conditions,… Consequently, the answer “There are abundant number of papers that report the thickness of 3 layered films fabricated using functional inks with nano particles” is totally unacceptable. The authors must directly measure the thickness of their layers.
The authors have no means to perform this experiment. Based on literature our sample is still considered a thin film sample.
Hopefully in a future study the thickness can be provided.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Authors have well responded to reviewers’ comments. The manuscript has been greatly revised and the English has been improved. Introduction section has been revised for further clarifying the novelty of this manuscript. Meanwhile, the layout of this manuscript is proper, the figures are acceptable, and the section of the results and discussions is substantial. Overall, the revised manuscript can be basically accepted for publication in this journal.

Author Response

Thank you.