Pulse Laser Irradiation Control Method for Blind Via-Hole Drilling of Printed Wiring Boards Based on High-Speed Camera Monitoring

2016 ◽  
Vol 874 ◽  
pp. 285-290 ◽  
Author(s):  
Koji Kanki ◽  
Munetaka Iozumi ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
Keiji Ogawa
Keyword(s):  
Laser Irradiation ◽  
High Speed ◽  
Processing Time ◽  
Control Method ◽  
Hole Drilling ◽  
Peak Time ◽  
High Speed Camera ◽  
Printed Wiring Boards ◽  
Pulse Irradiation ◽  
Multiple Pulses

In recent years, the performance and miniaturization of portable information devices have rapidly advanced. The build-up process is often used in the manufacturing of printed wiring boards (PWBs) for high-density circuits. At present, CO2 laser beams are generally used in the build-up process to drill blind via holes (BVHs) that connect copper foils. However, Cu direct drilling is problematic in that it produces a copper overhang as a result of copper and resin, with different decomposition points, being melted simultaneously. Overhang could cause an adverse effect in plating the hole for connectivity. However, only few studies have investigated Cu direct processing for drilling BVHs. At an actual production site of PWBs, the number of processing holes is enormous, which leads to neglecting the quality of each processed hole. Therefore, we focused on pulse drilling, which involves laser irradiation using short multiple pulses to reduce the thermal effect. Pulse drilling could reduce overhang compared to single pulse irradiation; however, it lengthens the total processing time. Pulse irradiation after BVH formation would be unnecessary, since it could cause thermal damage to the hole and lengthen the processing time. Therefore, during pulse irradiation, it is essential to distinguish whether a BVH is formed. We observed the value of the motion graph, which was acquired from the high-speed camera images. The motion graph shows the luminance value of an image at a given time of the video. Based on the peak time of the motion graph during each pulse, we proposed a method to distinguish BVH formation during multiple pulse drilling.

Process Design and Control Method of Laser Via Hole Drilling of Printed Wiring Boards Based on High Speed Camera Monitor

2017 ◽  
Author(s):  
Koji Kanki ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
Keiji Ogawa
Keyword(s):  
High Speed ◽  
Copper Foil ◽  
Control Method ◽  
Irradiation Time ◽  
Hole Drilling ◽  
Drilling Process ◽  
High Speed Camera ◽  
Printed Wiring Boards ◽  
Laser Method ◽  
Direct Laser

In recent years, the performance and miniaturization of portable information devices have rapidly advanced. The build-up process is often used in the manufacturing of printed wiring boards (PWBs) for high-density circuits. At present, CO2 laser beams are generally used in the build-up process to drill blind via holes (BVHs) that connect copper foils. The Cu direct-laser method is often used in this process, which irradiates laser to drill the copper foil and insulation layer simultaneously. Cu direct-laser involves a complex phenomenon because it drills copper and resin, with different decomposition points, at the same time. However, only few studies have been made in this field. This report focuses on monitoring Cu direct-laser drilling with a high-speed camera. We drilled holes with four different laser power outputs, 25 W, 50 W, 75 W, and 95 W and measured the size of the drilled holes. During the drilling process, the camera captured the emission of scattering materials in the PWBs. We have processed the images obtained from the camera to observe the scattering material. As a result, we found out that changes in the amount of scattering occur on four occasions: when the outer copper foil is drilled through, when the drilled depth reaches the inner copper foil, when the increase rate of the hole diameter is reduced, and when the inner copper foil is drilled through. Based on these results, the suitable laser irradiation time can be determined for different drilling conditions.

Optimization of Feed Speed and Stroke for Step Micro Hole Drilling of Printed Wiring Boards by Response Surface Method

2012 ◽  
Vol 523-524 ◽  
pp. 509-514 ◽  
Author(s):  
Naoya Noguchi ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
Keiji Ogawa ◽  
Yutaka Takeda
Keyword(s):  
Response Surface ◽  
Response Surface Method ◽  
High Speed ◽  
Hole Drilling ◽  
Feed Speed ◽  
Printed Wiring Boards ◽  
Step Cycle ◽  
Stroke Length ◽  
Surface Method ◽  
Micro Drilling

There have been few reports dealing with the drilling of printed wiring boards (PWBs) with micro-drills that are smaller than 0.2 mm in diameter, and super-high-speed spindles that are higher than 160,000 rpm. In these cases, preventing the micro-drill from breaking and keeping the position accuracy of the drilled hole has been difficult. We therefore focus on the high-speed step-drilling method and short stroke as a novel way of resolving these problems. On the other hand, determining the complicated combination of feed speed, rapid feed speed, and stroke length is difficult. Under these backgrounds, in this report we propose a fast-feed step cycle that use fast-feed command without the processing feed. Thus, we attempted to apply the response surface method to optimize these parameters. As a result, a proposed method was found to be effective to improve the drilled hole quality and drilling efficiency in such kinds of micro-drilling of the PWBs.

scholarly journals Investigation of Er:YAG laser-activated irrigation for the removal of biofilm and observations of laser-induced cavitation behavior

2022 ◽  
Author(s):  
Taiji Nagahashi ◽  
Yoshio Yahata ◽  
Keisuke Handa ◽  
Masato Nakano ◽  
Shigeto Suzuki ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Root Canal ◽  
High Speed ◽  
Er:Yag Laser ◽  
Positive Control ◽  
High Speed Camera ◽  
Pulp Chamber ◽  
Root Canal Irrigation ◽  
Biofilm Removal ◽  
The Impact

Abstract Background We investigated the biofilm removal effects of LAI using a pig model, focusing on the impact of the fiber tip position, and used a high-speed camera to observe the occurrence and positioning of the cavitation associated with laser irradiation. Methods A total of 16 roots of deciduous mandibular second premolars from 4 pigs were used. After a pulpectomy, the canals were left open for two weeks and sealed for 4 weeks to induce intraradicular biofilm. Then, root canal irrigation was performed with Er:YAG laser activation. The fiber tip was inserted at two different positions, i.e., into the root canal in the intracanal LAI group and into the pulp chamber in the coronal LAI group. Intracanal needle irrigation with saline or 5% NaOCl was utilized in the positive control and CNI groups. SEM and qPCR were carried out to evaluate treatment efficacy. For qPCR, ANOVA and a Tukey-Kramer post hoc test were performed with α = 0.05. A high-speed camera was used to observe the generation of cavitation bubbles and the movement of the induced bubbles after laser irradiation. Results The intracanal and coronal LAI groups showed significantly lower amounts of bacteria than either the positive control or CNI groups. There was no significant difference found between the intracanal and coronal LAI groups. SEM images revealed opened dentinal tubules with the destruction of biofilm in both LAI groups. High-speed camera images demonstrated cavitation bubble production inside the root canal after a single pulse irradiation pulse. The generated bubbles moved throughout the entire internal multi-rooted tooth space. Conclusions Coronal LAI can generate cavitation in the root canal with a simply placed fiber inside the pulp chamber, leading to effective biofilm removal. This method could thus contribute to the future development of endodontic treatments for refractory apical periodontitis caused by intraradicular biofilm.

scholarly journals Investigation of Er:YAG laser-activated irrigation for the removal of biofilm and observations of laser-induced cavitation behavior

2021 ◽  
Author(s):  
Taiji Nagahashi ◽  
Yoshio Yahata ◽  
Keisuke Handa ◽  
Masato Nakano ◽  
Shigeto Suzuki ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Root Canal ◽  
High Speed ◽  
Er:Yag Laser ◽  
Positive Control ◽  
High Speed Camera ◽  
Pulp Chamber ◽  
Root Canal Irrigation ◽  
Biofilm Removal ◽  
The Impact

Abstract BackgroundWe investigated the biofilm removal effects of LAI using a pig model, focusing on the impact of the fiber tip position, and used a high-speed camera to observe the occurrence and positioning of the cavitation associated with laser irradiation.MethodsA total of 16 roots of deciduous mandibular second premolars from 4 pigs were used. After a pulpectomy, the canals were left open for two weeks and sealed for 4 weeks to induce intraradicular biofilm. Then, root canal irrigation was performed with Er:YAG laser activation. The fiber tip was inserted at two different positions, i.e., into the root canal in the intracanal LAI group and into the pulp chamber in the coronal LAI group. Intracanal needle irrigation with saline or 5% NaOCl was utilized in the positive control and CNI groups. SEM and qPCR were carried out to evaluate treatment efficacy. For qPCR, ANOVA and a Tukey-Kramer post hoc test were performed with α=0.05. A high-speed camera was used to observe the generation of cavitation bubbles and the movement of the induced bubbles after laser irradiation.ResultsThe intracanal and coronal LAI groups showed significantly lower amounts of bacteria than either the positive control or CNI groups. There was no significant difference found between the intracanal and coronal LAI groups. SEM images revealed opened dentinal tubules with the destruction of biofilm in both LAI groups. High-speed camera images demonstrated cavitation bubble production inside the root canal after a single pulse irradiation pulse. The generated bubbles moved throughout the entire internal multi-rooted tooth space.ConclusionsCoronal LAI can generate cavitation in the root canal with a simply placed fiber inside the pulp chamber, leading to effective biofilm removal. This method could thus contribute to the future development of endodontic treatments for refractory apical periodontitis caused by intraradicular biofilm.

Real-Time Auto-Light System for High-Speed Camera

2013 ◽  
Vol 397-400 ◽  
pp. 1418-1421
Author(s):  
Hua Yang ◽  
Min Hua Liang
Keyword(s):  
Real Time ◽  
Exposure Time ◽  
High Speed ◽  
Large Scale ◽  
Control Method ◽  
High Speed Camera ◽  
Light System ◽  
Time Control ◽  
High Quality Image ◽  
Variance Weighted Information Entropy

In order to obtain stable and high quality image from high-speed camera in real time under different environment, the system hardware based on TMS320DM642 is designed and a complex control method is proposed to realize auto-light control rapidly by harmonizing alterable diaphragm and camera exposure time. The algorithm of the auto-light system mainly consists of two parts: the analysis of brightness information based on Variance weighted information entropy, camera exposure time control and alterable diaphragm control based on data analysis. The project results show that the algorithm has rapid convergence and strong adaptability, and the system can realize large-scale and real-time auto-light at different conditions.

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