Validation of Heat-Level Vapor Phase Soldering Process and Workspace Leakage Detection with Applied Pressure Sensors
Round 1
Reviewer 1 Report
This paper provides readers with some intresting information of new monitoring framework for VPS system by the atomospheric pressure gage sensor. However, the reviewer can not find enough evidence for validating the method. The authors should present other measurable parameters (such as vaper column height, substrate position) which must be corelated to pressure values quantitatively as well as detailed corelation to temerature. Otherwise readers might not be able to fully understand the significance of what the presure change really means during the VPS process.
For some details, please check and consider the following points:
Page 1 Line 23 [abstract]
When you say "the buildup of the vapour column", how can it be measureable ? Is it possible to observe by image sensors and to detect the column height?
Page 3 Line 99
By "A new gage type sensor", do you mean the sensor you used is newer than other conventional gage type sensors, or just diffrent from TC sensor?
Page 3 Line 107
It seems that Q-450 is a product number. Please add the manufacturer information.
Page 4 Line 143-148 , Figure 2
Describe the size of the HSC sensor and its sensing tube diameter?
Page 4 Line 140-141, and 149-151
Add the sampling rate for temerature/pressure measurments.
Page 5 Line 188, 194
Please use italic for varables in equations.
Page 6 Line 218-223
Can't we identify 4 phases by only temperature monitoring? The authors insisted they can identify the fine details of phases. But the physical interpretation of the pressure curve might be not well-understandable for readers since there is no evidence data shown in the manuscript; ex) the relation between the abrupt pressure change points and vapor column height, or PCB height.
Page 7 Line 238-243
Authors recommend the pressure measurement just because temperature monitoring takes longer time to detect the saturation point. But to what extend does it prolonged for detection? If the instrument is controlled by a modern PC, the first differencial of temperature curve might be easy to attain concurrently. More importantly, authors should clarify the pysical meaning of the pressure curves by showing quantitative corelations between the pressure, temperature diffrencial, and the height of saturated vapor column.
Page 7 Figure 5
This is an illustration for explanation of procedures, but not the data supporting your conclusion, the existence of 4 phases corelating to the machine status.
Page 8 Figure 6 and Figure 7
As for the overshoot ratio and relaxation time of pressure curve peaks, do they have some significance for VPS? Are these quantities instrument-specific or dependent to the instrument, (ex) the volume of instrument chamber?
Page 13 Referecne
Some typographical errors/missing periods found in references
4, 11, 21, 23, and 27.
Author Response
Dear Reviewer, please find our reply letter with the cover letter in the attached PDF file! We felt that the format would be better in a separate document.
Thank you for the thorough review, we feel that we put a lot of effort and significantly improved our article according to your commentary.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper presents and analyzes the very well organized experiments regarding:
-hydrostatic pressure profile, e.g. the timely synchronization with temperature measurements and the maximum of the pressure peaks obtained with different heating power settings;
-process sub-steps during the soldering with heat-level method;
-sensor feedback at the special case of leakage.
The experiments demonstrate capability to control the heat transfer in HL-VPS processes by vapor pressure measurements, offering also information about broke sealing of the workspace by vapor pressure flat signals.
Minor corrections of spell errors and text editing are necessary, regarding incorrect abbreviation introduced or not explained: PFA abbreviation appear in row 129 and explanation (perfluoroalkoxy) in 134, VOCs (row 337), OSH (row 386), word “signa” without “l”, row 355. From these errors point of view (could be more) it is necessary to rewire the paper text.
In figure 10 the graphical representation is wrong because is noted by mistake pressure not temperature.
Regarding row 304 “The vapour height around 60%” perhaps correct is 60 mm. Please clarified the table structure, content specifications and notes relating to table 1 & 2. Is not necessary to precise the pressure and temperature measurement units?
The assumption: “the flat geometry of a standard PCB thermally blends into the thermal mass of the metal support” (row 200) could be usable for the present experiment because was use non-populated PCB and measured in principal the hydrostatic pressure profile using HSG sensors type. In the real situation, the load is a complex PCBA with large mass and dimensions dispersion of their components with different thermal diffusivity, having a substrate also characterized by thermal diffusivity. As result, the defined thermophysical properties influence thermal relief at PCBA surface with consequences regarding thermal profile control. From this point of view will be necessary to continue the experiments with different PCBAs having the same components structure but different PCB substrate with solder joints quality control in order to define the HL-VPS process control by combined temperature and vapor pressure measurements.
Author Response
Dear Reviewer, please find our reply letter with the cover letter in the attached PDF file! We felt that the format would be better in a separate document.
Thank you for the thorough review, we feel that we put a lot of effort and significantly improved our article according to your commentary.
Author Response File: Author Response.pdf
Reviewer 3 Report
Dear coauthors,
Please consult the attached file (pdf format) and operate the suggested minor corrections/additions.
Comments for author File: Comments.pdf
Author Response
Dear Reviewer, please find our reply letter with the cover letter in the attached PDF file! We felt that the format would be better in a separate document.
Thank you for the thorough review, we feel that we put a lot of effort and significantly improved our article according to your commentary.
Author Response File: Author Response.pdf
