Study on the Performances of Toughening UV-LED-Cured Epoxy Electronic Encapsulants
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe paper deals with the:
‘Study on the performances of Toughening UV-LED cured epoxy electronic encapsulants’,
Co-written by Xiaolong Dai, and Jianbo Li, from Tongji University (Shanghai, China)
This paper investigates three toughening agents on the performance of UV-LED cured epoxy electronic encapsulants. Are evaluated curing behavior, thermomechanical properties, and impact resistance in alicyclic epoxy resins, to potential applications in more environmentally friendly UV-cured electronic encapsulation.
1. Introduction
P1/13, Paragraph 3-Line 6. Here is identified the problem with Core-shell rubber particles in UV-LED cured epoxy systems: ‘may influence the dispersion and phase separation of CSR within the epoxy matrix’
Comments: what’s happened (mechanism/default) in dispersion and phase separation?
Line 4: ‘the incorporation of CSR can improve the toughness and flexibility of the epoxy resin’
Comments: can the authors give estimation in improvements? It is 1% more in toughness and flexibility?
P2/13, Paragraph 1-Line 5. Here is identified the problem with Nano-silica particles in UV-LED cured epoxy systems: ‘their dispersion and interaction with the epoxy matrix under UV-LED curing conditions must be thoroughly examined’
Comments: what’s happened (mechanism/default >> reactivity is kinetics?) in dispersion and interaction?
Line 3: ‘NSP enhances mechanical properties and thermal stability by improving the resin's modulus and reducing the coefficient of thermal expansion [17,18,19]’
Comments: can the authors give estimation in improvement? It is 1% more?
P2/13, Paragraph 2-Line 5. Here is identified the benefit with Epoxidized polybutadiene in UV-LED cured epoxy systems: ‘EPB's effectiveness as a toughening agent is influenced by the rapid curing process and low curing temperatures. EPB can enhance the flexibility and impact resistance of the UV-LED cured epoxy resin…’
Comments: no limitation are expected ; as residual constraint, default as porous system etc.?
Comments: can the authors give estimation in improvement? It is 1% more in flexibility, impact resistance?
P2/13, Paragraph 3. UV-LED curing technology. Has/Is this technology been used from a long date? Can we add a little history please?
2. Materials and Methods
P2/13, 2.1. Experimental Reagents:
Maybe we can add a sentence as:
The chemicals are:
- one alicyclic epoxy resin as 3,4-Epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (EEC), Daicel CEL-LOXIDE 2021P, Japan;
- Triarylsulfonium hexafluoroantimonate salt (PAG), PAG20102, industrial grade, Qiangli Chemical, China;
- Core-Shell Rubber particles (CSR) with a core-shell rubber dispersion solution, MX553 from Kaneka, Japan;
- Nano-Silica Particles (NSP) with a nano-silica dispersion solution, Evonik Nanopox E601, Germany;
- and Epoxidized PolyButadiene (EPB), Daicel EPOLEAD PB3600, Japan.
Other materials are:
- Spherical silica, FB35 from Denka, Japan,
(…)
All chemicals were used without special treatment before use.
2.2. Sample Preparation:
Comments: what is the role of PAG with EEC?
Comments: ‘Then, NSP, CSR, EPB, and other materials were added and mixed respectively.’ What are the ‘other materials? Please add them. What is their role?
Comments: what is the role of Spherical silica (FB35 from Denka, Japan)?
2.3. Experimental Testing and Characterization:
In part last part ‘Die shear strength (DSS) tests‘ it is saying ‘10 samples were tested repeatedly in each experimental group, and the average value was taken.’
Comments: for each part ‘Curing depth testing method’ ‘DMA’ ‘TMA’ TGA’ ‘UV-DSC’ ‘SEM’ 3 points bending tests’, how many samples were prepared and how many repetition data collection?
3. Results
3.1. UV-DSC Analysis
P4/13, Line 9.
Add a point between the 2 sentences: ‘Core-shell rubber particles (CSR) also broadened the exothermic peak The rub…‘
Maybe authors can add the global kinetics of each reaction by integration of DSC peaks? And can have access to the calculation of heat energy for each system, to compare with the given discussion.
Be careful in authors citation: ‘Pramanik M [27] showed…’ & ‘Baek,D [28]’
3.2. UV Curing Depth
What to add uncertainties/error bars for the discussion?
3.2. Thermal Properties of UV epoxy adhesive modified by different toughener.
3.2.1. Dynamic Mechanical Analysis (DMA)
P6/13, ‘Baek,D [28] also found that more CSR content in epoxy adhesive, Tg shifted to higher temperature.’
Is it possible to add estimation in improvements? Maybe calculate estimation and plot them versus the systems?
In the works of Baek,D [28], no more discussion is given? What is new in the present work?
3.2.2. Thermomechanical Analysis (TMA)
P7/13, What about to add uncertainties for the discussion?
3.2.3. Thermogravimetric Analysis (TGA)
P7/13, ’The second major weight loss occurred around 450°C, indicating the breakdown of the remaining polymer structure.’
What are the remaining polymer structures?
No degradation in Core-Shell Rubber particles (CSR)? No degradation in Nano-Silica Particles (NSP)? No degradation in Epoxidized PolyButadiene (EPB)?
Table 3: What about to add uncertainties for the discussion?
3.3. Mechanical Properties and Fractured Surfaces of UV epoxy adhesive modified by different toughener.
Table 4 ‘In Load’, do we need all the number after the coma?
Table A, idem What about to add uncertainties for the discussion? But results can be affected by voids, as discussed? What is author’s opinion?
Can effect (voids, degradation, default) can be see in 3.4. Chiplet Adhesion (DSS)? and in 3.5. Water absorption?
3.5. Water absorption
Add a point between the 2 sentences: ‘…which can improve moisture resistance; The inter-…’
4. Discussion
Maybe authors can improve discussion by adding works done and found in references? /Perhaps the article can be improved with better discussion by citing works done in the cited references.
References
Please check all quotes. Data is sometimes missing.
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors1. The abstract should be concise and needs to be rewritten with the most important results of the findings.
2. Provide more details of the sample preparation.
3. Figure 6. Scales of the SEM images are not visible.
4. I think section 4 is the conclusion of the findings, not the discussion please recheck and provide a conclusion
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript by Li and Dai describes different polymeric forms, which consisted of varying ratios of NSP, CSR, and EPB hardening agents were mixed with preexisting UV-LED electronics encapsulants were casted into molds. They were hardened in a UV chamber and the physical properties were measured by DMA, TMA, TGA, UV-DSC, SEM, and DSS. The depths at which the UV could penetrate and cure the forms was also measured. The addition of the hardening additives improved the toughness and thermal stability of the electrical insulators. However, the EPB significantly diminishes the storage modulus of the cured materials.
Overall the manuscript is well done and the presentation/experimentation is adequate. Only suggestion would be to test oxygen permeability if able, but is not absolutely necessary.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThanks for the corrected V2.
Last point / last revision: to check please, the citations in the references are not written in the same way, shouldn't we harmonize for the quality of the manuscript?
Sometimes it is 'Polymers 2023, 15, 1689', sometimes 'Polymers. 2021;13(13):2161', or 'Organic Electronics, Volume 13, Issue 1, 2012, Pages 53-57', etc.
Sometimes information is missing 'Polymer Science, Series A,2019.'
Author Response
Please see the attachment
Author Response File: Author Response.pdf
