Effects of Isothermal Aging on Interfacial Microstructure and Shear Properties of Sn-4.5Sb-3.5Bi-0.1Ag Soldering with ENIG and ENEPIG Substrates
and Dianlong Wang 1Round 1
Reviewer 1 Report
The paper is sufficiently novel and interesting to warrant publication, it results in an advance to the current scientific literature. The abstract reflect the content and summarize the research problem.
In the experimental part the author accurately explain how the data was collected. The authors give the sufficient information about the preparation of specimens and also sufficient information that the experiment can be reproduced.
The discussion is supported by the results, clearly explained the obtained results focused on the scientific sense. It specifically shows how the work resulted in an advance.
The conclusion sounds and justifiable as based on the results and discussion.
The structure of the paper is well-organized, the information flows in a logical manner.
The English expression is clear, understandable and easy to interpret.
The paper is acceptable in the present form after revisions. It gives the adequate reference to the prior work. It does not contain errors in mathematics, logic or experimental procedure. All figures and tables are necessary, they prove their point.
The paper is not acceptable in the present form.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
2. Materials and Methods
Please insert the information of component and PCB.
3. Results and discussion
In the case of interfacial reaction of Sn–3.0Ag–0.5Cu solder jointed with ENIG and ENEPIG surface finishes, Ni3Sn4 was inhibited in the ENEPIG joints, which suppressed the excessive voids formation as compared to ENIG during thermal aging.
Ref: C. F. Tseng et. al., "Suppressing Ni3Sn4 formation in the Sn–Ag–Cu solder joints with Ni–P/Pd/Au surface finish", Materials Letters, Volume 65, Issues 21–22, November 2011, Pages 3216-3218.
Why is the result of Sn-Ag-Cu solder case different from the result of Sn-Sb-Ag solder case?
I think discussions on this point are necessary.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Even the article is interesting the major revision is needed. My main comment which supports this decision is that the authors used just two samples (this information is on page 2 line 96) for each combination for testing and analyses. This is absolutely insufficient number of samples for testing (like shear test and other analyses) and obtaining generally applicable scientific results.
- Correct the format of degrees of Celsius in the abstract; see: 150oC
- The intermetallic layers depend on soldering conditions; therefore, the authors should insert the shape of the temperature profile in the section Materials and Methods. There should also be information about used soldered components - material compositions of the out leads.
- The authors stated the information about equipment just in the case of the scanning electron microscope (SEM; ZEISS ULTRA55). Please add the information about other used equipment as well.
- Highlight the text in figure 3a- figure 3f, it is difficult to read.
- The information about the measurement of IMC thickness is missing. The IMC layers do have irregular shapes and authors should mention how did they measure and evaluate their thickness.
- How many samples were used for the share strength test for each combination solder alloy/surface finish/ ageing time? Just two?
- It is unclear to the reader to which samples the percentages belong in a sentence: “After 1000 h aging, the shear strength of the two solder joints decreased by 5.48% and 10.85%, respectively.”
- The information about the location from which the images of morphologies (see figure 9a - 9h) were taken is missing.
- The authors state in a sentence: “As presented in Figures 10a-d, the fracture position of the solder joint occurred in the solder matrix and gradually approaches the IMC interface.“ This trend of gradually approaching the fracture to the IMC layer was obvious in all tested samples or it was obvious only at selected samples? How many samples were analyzed in this way?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
The authors improved their manuscript and I recommend publishing it.
