Research on the Disassembly Process and Model of Waste Mobile Phone Circuit Board Components

Round 1

Reviewer 1 Report

1. Design of disassembly process is ambiguous

2.How this process is ecofriendly towards environment.

3.English presentation  is poor

4. How author has measured the thermal field distribution at 260 ⸰C ? and  the COMSOL image is not clear

5.Fig 7.  is need to be more informative.

 

 

1. Design of disassembly process is ambiguous

2.How this process is ecofriendly towards environment.

3.English presentation  is poor

4. How author has measured the thermal field distribution at 260 ⸰C ? and  the COMSOL image is not clear

5.Fig 7.  is need to be more informative.

 

Author Response

Reviewer 1 suggestion and reply

1. Design of disassembly process is ambiguous

Thank you for you suggestion, I have made modifications and revisions in the abstract according to your suggestions.

2. How this process is ecofriendly towards environment.

Thank you for you suggestion, We have conducted research on the volatile gases produced during the operation of the device and have published our findings publicly. In actual operation, the device does not generate wastewater pollution, and the produced volatile gases can be easily absorbed and treated before being discharged into the atmosphere at high altitude. The noise pollution caused by machine vibration has been resolved by adding an overall shield layer to the device, and the photos in the paper are internal photos of the device without the shield layer.

3. English presentation  is poor

Thank you for you suggestion,We have made efforts to modify the English expression.

4. How author has measured the thermal field distribution at 260 ⸰C ? and  the COMSOL image is not clear

      We dismantled the feeding part of the device and first heated it to a certain temperature. In addition, several thin metal wires were arranged inside the device, and a thermocouple probe was attached to the wires to collect temperature data through the drag-and-drop method.

5. Fig 7.  is need to be more informative.

Thank you for you suggestion, We believe that a clear explanation has been provided in the main text.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

General comments: The manuscript was well-written and very interesting.

 

Specific comments

 

The methodology part of the abstract is missing. This makes the abstract less informative.

 

The citation in line 28 is unusual. What is et al. for?

 

A sentence from lines 46 to 51 is incomplete/hanging and it needs recast.

 

Need to correct the superscript and subscript for all the equations and explanations of these terms in intext.

 

A proper explanation should be given on what caused the disassembly rate to decrease as the temperature exceeds 250 ˚C. Very conflicting reasons have been given in this manuscript.

 

What are the most difficult parts of WPCBs to disassemble by this technique and what would be the reason for that?

 

Maybe the conclusions should be shortened a bit.

English quality is ok.

Author Response

Reviewer 2 suggestion and reply

 

1 . The methodology part of the abstract is missing. This makes the abstract less informative.

Thank you for you suggestion, I have made modifications and revisions in the abstract according to your suggestions

2. The citation in line 28 is unusual. What is et al. for?

Thank you for you suggestion, there are have other two institutions, one is Producer Responsibility Extension Industry Technology Innovation Alliance; The other one is China Green Supply Chain Alliance Electrical and Electronic Products Special Committee;

3. A sentence from lines 46 to 51 is incomplete/hanging and it needs recast.

Need to correct the superscript and subscript for all the equations and explanations of these terms in intext.

Thank you for you suggestion, Based on your modification suggestions, we have made a few modifications.

4. A proper explanation should be given on what caused the disassembly rate to decrease as the temperature exceeds 250 ˚ Very conflicting reasons have been given in this manuscript.

Thank you for you suggestion, I have already explained it in the main text.

5. What are the most difficult parts of WPCBs to disassemble by this technique and what would be the reason for that?

Thank you for you suggestion, I think the most difficult parts is how to further reduce the overall energy consumption of the equipment and reduce its operating costs.

6. Maybe the conclusions should be shortened a bit.

Thank you for you suggestion, I have simplified the conclusion.

Author Response File: Author Response.pdf

Reviewer 3 Report

It is urgent to find clean and efficient ways to resource the obsolete mobile phones since lots of them will be discarded as new generation is produced so quickly. If not, severe environment pollution will be discharged into our routine life. The key procedure for the resource is the dismantling of the electronic components to classified processes. Here, the authors invented an automated disassembly equipment for waste printed circuit boards (WPCBs) with optimized process conditions of a heating temperature of 250℃ and an equipment amplitude of >3.66mm. Their results showed that the dismantling rate of electronic components and metal shields can be up to 98%, but disassembly of components with underfill is less effective. Results from simulation and actual experimental suggest the thermal field was uniform. The authors suggest that their equipment and process can be used to disassemble large quantities of WPCB components. There are some questions for the authors to consider to improve their article.

 

1.      What are the main advantages of their invention comparing with the currently used equipment? What are the key challenges in this field? How do they design their equipment and the key parameters to dissolve them. Please give a discussion using tables or schemes to show their creativity.

2.      The authors mentioned that their equipment is less effective in the disassembly of components with underfill. However, they do not give the way to address this issue. Please explain it.

3.       It seems that the dismantling mechanism is based on the heating and vibration of the equipment. However, the authors also mention the different parts (e.g., integrated chips and capacitors) with different structures and different binding forces. Please give the explain how to treat different parts using the same procedure or the same parameters and how the vibration energy is changed to tear the circuit parts from the substrate or solders together with the surface/interface tension.

4.      Please give the chemical composition in their heating tanks.

Author Response

Reviewer 3 suggestion and reply

 

It is urgent to find clean and efficient ways to resource the obsolete mobile phones since lots of them will be discarded as new generation is produced so quickly. If not, severe environment pollution will be discharged into our routine life. The key procedure for the resource is the dismantling of the electronic components to classified processes. Here, the authors invented an automated disassembly equipment for waste printed circuit boards (WPCBs) with optimized process conditions of a heating temperature of 250℃ and an equipment amplitude of >3.66mm. Their results showed that the dismantling rate of electronic components and metal shields can be up to 98%, but disassembly of components with underfill is less effective. Results from simulation and actual experimental suggest the thermal field was uniform. The authors suggest that their equipment and process can be used to disassemble large quantities of WPCB components. There are some questions for the authors to consider to improve their article.

1. What are the main advantages of their invention comparing with the currently used equipment? What are the key challenges in this field? How do they design their equipment and the key parameters to dissolve them. Please give a discussion using tables or schemes to show their creativity.

Thank you for you suggestion, my main response to your question is as follows:

(1) The main advantages of this equipment are that the operating technical threshold is low, it is more closely aligned with actual production, and the initial investment and repair fee scale is small.

(2)The main challenges are to further reduce the overall energy consumption of the equipment and reduce operating costs.

(3)The design of the equipment is first simulated using finite element software, and the parameters obtained from the simulation design are used to optimize the design parameters of the actual product, based on which the manufacturing and operational research of the actual equipment are carried out.

2. The authors mentioned that their equipment is less effective in the disassembly of components with underfill. However, they do not give the way to address this issue. Please explain it.

Thank you for you suggestion. After surface mount electronic components are soldered in place, some of the components will be resealed with glue (a type of resinous organic material with no obvious softening point). The softening temperature of the glue is much higher than the melting point of the solder, which means that under optimal disassembly temperatures, components sealed with glue cannot be dismantled. That is to say, although the solder connecting the components has melted, the presence of glue prevents this equipment from effectively dismantling such surface mount electronic components.

3. It seems that the dismantling mechanism is based on the heating and vibration of the equipment. However, the authors also mention the different parts (e.g., integrated chips and capacitors) with different structures and different binding forces. Please give the explain how to treat different parts using the same procedure or the same parameters and how the vibration energy is changed to tear the circuit parts from the substrate or solders together with the surface/interface tension.

Thank you for you suggestion.The overall excitation force of the equipment is controlled by two vibration motors. The internal structure of the vibration motor includes two triangular metal weights. When these two metal weights are symmetrically installed, the eccentricity and excitation force of the vibration motor are minimized. On the contrary, when these two metal weights are partially overlapped during installation, the excitation force of the vibration motor will increase. The greater the overlap, the larger the eccentricity and excitation force of the motor. Therefore, adjusting the overlap area of the weight blocks can regulate the overall excitation force of the equipment. This principle can be applied in many industrial fields such as vibrating screening and conveying.

4. Please give the chemical composition in their heating tanks.

Thank you for you suggestion.It has already been provided in the main text.

Author Response File: Author Response.pdf

Reviewer 4 Report

This manuscript presents the design of an automated disassembly equipment for waste mobile phone circuit boards. However, I would not recommend publishing this article in its current format. Please find my comments below.

1) Many methods have been published for disassembling WPCB components. It is essential to highlight the advantages of the proposed method compared to other published methods. The introduction should provide more information on this aspect.

2) The reviewer understands that the equipment is a prototype. The reviewer recommends adding a brief discussion about how to reduce energy consumption.

3) The manuscript needs significant improvement in terms of writing quality and proofreading. For example,

Line 168 and 169: “where fvi represents the vertical disassembly force applied per solder joint, gci represents the gravitational force per solder joint pin, and fsi represents”. Please use the appropriate format for parameters (fvi, gci and fsi), and correct other parameters in the manuscript.

Line 287 and 288: “and chips A-E and capacitor A capacitor B are taken from the Huawei P9 mobile phone”

 

 

Minor editing of English language required.

Author Response

Reviewer 4 suggestion and reply

The paper reports about a system for de-assembling electronic devices from waste PCBs, with particular reference to waste mobile phones. The paper includes a good introduction where the motivations of the work are highlighted, the description of the apparatus, simulation and experimental results. The English -as far as I can judge- is good and fluent.

Below my advice for improving the paper:

(1)The organization of chapter can be improved: I suggest to separate simulations from experiments in different chapters. Results includes some theoretical part on the force that would fit better the methods section

Thank you for you suggestion. Your opinion is very good. After comprehensive consideration, considering the overall nature of this paper, we have only made a few modifications and supplements.

(2)Lines 52-57. Net clear to me. Please rephase. Are any of the chips de-assembled to be employed in new phones? Please clarify.

Thank you for you suggestion. we have made some modifications and supplements.

The dismantling of chips is mainly for the degradation of high-performance computing and storage chips in these mobile phones, such as low-end products such as smart toys and functional communication devices.

(3)Why did you not use antioxidant?

Thank you for you suggestion. Considering the operating costs, the use of antioxidants is beneficial for disassembling surface mount electronic components. However, higher disassembly temperatures result in the release of more volatile gases, which is harmful to environmental protection. The working principle of our disassembly equipment is to work at the lowest possible temperature, achieve the highest possible disassembly efficiency, and keep the disassembly system as simple as possible.

(4)How could you improve the process for chips with underfill?

Thank you for you suggestion. Currently, our research team does not have a better solution. In order to achieve cascade utilization of the chip, it is possible to standardize the manufacturing processes or standards of production enterprises in the future. As a good solution, it is advisable to minimize the use of adhesives.

(5)There are several inaccuracies in the format:

o   The reference in text does not agree to MDPI format,

o   line spacing is not uniform

o   simbols in formulas and text are different (see, e.g. line 165)

Thank you for you suggestion. we have made some modifications. About references, we will standardize the references based on MDPI.

 

Author Response File: Author Response.pdf

Reviewer 5 Report

The paper reports about a system for de-assembling electronic devices from waste PCBs, with particular reference to waste mobile phones. The paper includes a good introduction where the motivations of the work are highlighted, the description of the apparatus, simulation and experimental results. The English -as far as I can judge- is good and fluent.

Below my advice for improving the paper:

-         The organization of chapter can be improved: I suggest to separate simulations from experiments in different chapters. Results includes some theoretical part on the force that would fit better the methods section

-         Lines 52-57. Net clear to me. Please rephase. Are any of the chips de-assembled to be employed in new phones? Please clarify.

-         Why did you not use antioxidant?

-         How could you improve the process for chips with underfill?

-         There are several inaccuracies in the format:

o   The reference in text does not agree to MDPI format,

o   line spacing is not uniform

o   simbols in formulas and text are different (see, e.g. line 165)

Author Response

 

Reviewer 4 suggestion and reply

The paper reports about a system for de-assembling electronic devices from waste PCBs, with
particular reference to waste mobile phones. The paper includes a good introduction where the
motivations of the work are highlighted, the description of the apparatus, simulation and
experimental results. The English -as far as I can judge- is good and fluent. Below my advice for improving the paper:

(1)The organization of chapter can be improved: I suggest to separate simulations from
experiments in different chapters. Results includes some theoretical part on the force that
would fit better the methods section

Thank you for you suggestion. Your opinion is very good. After comprehensive consideration, considering the overall nature of this paper, we have only made a few modifications and
supplements.

(2)Lines 52-57. Net clear to me. Please rephase. Are any of the chips de-assembled to be
employed in new phones? Please clarify.

Thank you for you suggestion. we have made some modifications and supplements. The dismantling of chips is mainly for the degradation of high-performance computing and
storage chips in these mobile phones, such as low-end products such as smart toys and functional
communication devices.

(3)Why did you not use antioxidant?

Thank you for you suggestion. Considering the operating costs, the use of antioxidants is
beneficial for disassembling surface mount electronic components. However, higher disassembly
temperatures result in the release of more volatile gases, which is harmful to environmental
protection. The working principle of our disassembly equipment is to work at the lowest possible
temperature, achieve the highest possible disassembly efficiency, and keep the disassembly
system as simple as possible.

(4)How could you improve the process for chips with underfill?

Thank you for you suggestion. Currently, our research team does not have a better solution. In
order to achieve cascade utilization of the chip, it is possible to standardize the manufacturing
processes or standards of production enterprises in the future. As a good solution, it is advisable
to minimize the use of adhesives.

(5)There are several inaccuracies in the format:
o The reference in text does not agree to MDPI format,

o line spacing is not uniform

o simbols in formulas and text are different (see, e.g. line 165)

Thank you for you suggestion. we have made some modifications. About references, we will
standardize the references based

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Can be accept after minor English change.

 

Can be accept after minor English change.

 

Author Response

Thank you for your suggestion, In accordance with your advice, we have made modifications to the English writing aspects throughout the entire manuscript. Please review the revisions.

Author Response File: Author Response.pdf

Reviewer 3 Report

Now the revised version is OK for publication.

Author Response

Thank you for your suggestion, In accordance with your advice, we have made modifications to the English writing aspects throughout the entire manuscript. Please review the revisions.

Author Response File: Author Response.pdf

Reviewer 4 Report

The reviewer does not believe that the authors have made the necessary changes based on the reviewer's comments or suggestions. Please find the comments provided below.

This manuscript presents the design of an automated disassembly equipment for waste mobile phone circuit boards. However, I would not recommend publishing this article in its current format. 

1) Many methods have been published for disassembling WPCB components. It is essential to highlight the advantages of the proposed method compared to other published methods. The introduction should provide more information on this aspect.

2) The reviewer understands that the equipment is a prototype. The reviewer recommends adding a brief discussion about how to reduce energy consumption.

3) The manuscript needs significant improvement in terms of writing quality and proofreading. For example,

Line 168 and 169: “where fvi represents the vertical disassembly force applied per solder joint, gci represents the gravitational force per solder joint pin, and fsi represents”. Please use the appropriate format for parameters (fvi, gci and fsi), and correct other parameters in the manuscript.

Line 287 and 288: “and chips A-E and capacitor A capacitor B are taken from the Huawei P9 mobile phone”

 

The manuscript needs significant improvement in terms of writing quality and proofreading. For example,

Line 168 and 169: “where fvi represents the vertical disassembly force applied per solder joint, gci represents the gravitational force per solder joint pin, and fsi represents”. Please use the appropriate format for parameters (fvi, gci and fsi), and correct other parameters in the manuscript.

Line 287 and 288: “and chips A-E and capacitor A capacitor B are taken from the Huawei P9 mobile phone”

 

Author Response

The reviewer does not believe that the authors have made the necessary changes based on the reviewer's comments or suggestions. Please find the comments provided below.

This manuscript presents the design of an automated disassembly equipment for waste mobile phone circuit boards. However, I would not recommend publishing this article in its current format. 

• Many methods have been published for disassembling WPCB components. It is essential to highlight the advantages of the proposed method compared to other published methods. The introduction should provide more information on this aspect.

  Thank you for you suggestion. Your opinion is very good. We have carefully considered the issue you raised, and given that the current mainstream dismantling process involves the use of a hot air gun, and constrained by the topic of this article, we have not done too much detailed supplement or in-depth description for other processes. We have provided relevant references in the main text. If readers are interested, they can further learn about relevant technologies based on the references. In response to this issue, I would like to express my gratitude to you and strive to provide targeted and detailed discussions based on your suggestions in the relevant papers we will publish in the future.

• The reviewer understands that the equipment is a prototype. The reviewer recommends adding a brief discussion about how to reduce energy consumption.

Thank you for you suggestion. According to your valuable suggestions, we have added a discussion on energy-saving measures in the conclusion and outlook section of this article. Please review it.

3) The manuscript needs significant improvement in terms of writing quality and proofreading. For example,

Line 168 and 169: “where fvi represents the vertical disassembly force applied per solder joint, gci represents the gravitational force per solder joint pin, and fsi represents”. Please use the appropriate format for parameters (fvi, gci and fsi), and correct other parameters in the manuscript.

Line 287 and 288: “and chips A-E and capacitor A capacitor B are taken from the Huawei P9 mobile phone”

Thank you for your suggestion. Based on your valuable suggestions, we have made significant efforts to revise the manuscript with a focus on improving readers' understanding. In accordance with your advice, we have made modifications to the English writing aspects throughout the entire manuscript. Please review the revisions.

 

 

 

 

Author Response File: Author Response.pdf

Reviewer 5 Report

The paper is now improved, the English still needs some revision.

the English still needs some revision.

Author Response

Thank you for your suggestion, In accordance with your advice, we have made modifications to the English writing aspects throughout the entire manuscript. Please review the revisions.

Author Response File: Author Response.pdf

Round 3

Reviewer 4 Report

The authors have addressed all of my comments. I have no further comments. Thank you!

Author Response

（1）Does the introduction provide sufficient background and include all relevant references?

 

Thank you for your suggestion. We have made additional elaborations to the content of the main text and added two new references, numbered [15] and [16]. Please refer to the specific details in the main text section and the revised references section. This article originally focused on the description of reprocessing techniques while undervaluing the aspect of resource efficiency. These two new references have enriched and expanded the discussions on resource utilization in this article. I have made appropriate additions in the main text, as highlighted. Please refer to the highlighted sections in the main text for more details.

 

（2）Are all the cited references relevant to the research?

Thank you for your suggestion. We have removed the statement regarding the establishment of an industrial park from the 30th reference, as it had weak relevance to the main theme of the article. This modification has added two references with high relevance and removed one reference with low relevance. As a result, the current number of references is 41.

 

（3）Is the research design appropriate?

 

Thank you for your suggestion. Your suggestions are helpful in improving our research standards. There were indeed some questionable aspects in the overall research and design of the article. However, considering that the framework of this particular article has already been established and has undergone multiple revisions, we will take note of conducting proper research design in future related papers.