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.

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.

Monitoring Method for Laser Via Hole Processing of Printed Circuit Boards Based on Two-Color Method With a High-Speed Video Camera

2020 ◽  
Author(s):  
Wataru Nakagawa ◽  
Ryuta Yamaguchi ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama
Keyword(s):  
High Speed ◽  
Printed Circuit Boards ◽  
Color Image ◽  
Irradiation Time ◽  
Single Pulse ◽  
Video Camera ◽  
Image Method ◽  
Drilling Process ◽  
Monitoring Method ◽  
Direct Laser

Abstract A build-up process is used to manufacture printed wiring boards (PWBs) for high-density circuits. Presently, CO2 laser beams are used to drill blind via holes (BVHs) that connect copper foils. The Cu-direct drilling process has received considerable attention but is problematic because it produces a copper overhang due to the complex processing phenomena. This report focuses on monitoring scattered matter by Cu-direct laser drilling with a high-speed camera and clarifying the factors related to processing quality while verifying the results by CFD (Computational Fluid Dinamics) analysis. Previous research has shown that processing progress can be made from temperature information using the two-color image method that can measure temperature without contact. However, the two-color image method generates noise in the temperature range (500–3000 °C) which is treated in this research. Filtering was possible by using the RGB data of each pixel on the image. By focusing on laser fluence, it became possible to estimate the laser irradiation time that can guarantee the quality in the drilled hole (BVH) in single pulse continuous irradiation.

Cu-Direct Via-Hole Drilling of Aramid Fiber Reinforced Build-Up Layer by CO2 Laser Beam

2005 ◽  
Author(s):  
Eiichi Aoyama ◽  
Toshiki Hirogaki ◽  
Keiji Ogawa ◽  
Nobuyuki Doi ◽  
Ryu Minagi
Keyword(s):  
Co2 Laser ◽  
Copper Foil ◽  
Effective Means ◽  
Hole Diameter ◽  
Hole Drilling ◽  
Printed Wiring Boards ◽  
Laser Absorption ◽  
Direct Laser ◽  
Via Hole ◽  
The Difference

This report describes the features of Cu-direct laser drilled hole quality on multi-layer Printed Wiring Boards (PWBs). Cu-direct laser drilling drills the outer copper foil and build-up layer at the same time, which makes it difficult to form a blind via hole (BVH) with high quality because the copper foil has high reflection coefficient for a CO2 laser with wavelength 10.6 μm. Therefore, this study focused on improving drilled hole qualities such as diameter and overhang. First, the influence of laser irradiation conditions on forming BVH and the drilled hole diameter were investigated in detail. Second, a new method employing thermography was proposed in order to evaluate the absorption of copper foil after surface treatment. Third, the effect of mixing fillers into the build-up layer in order to reduce the amount of overhang was shown to be effective both experimentally and theoretically. As a result, it is clear that decreasing the difference in the laser absorption rate of the outer copper foil is an effective means to control the hole diameter and reducing the heat characteristic difference between the outer copper foil and the build-up layer can effectively decrease overhang.

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.

Effect of Rapid-Feed Step-Drilling Cycle and Super-High-Speed Spindle for High-Speed Micro Drilling in Printed Wiring Boards

2010 ◽  
Vol 447-448 ◽  
pp. 836-840 ◽  
Author(s):  
Eiichi Aoyama ◽  
Toshiki Hirogaki ◽  
Keiji Ogawa ◽  
Satoshi Nojiri ◽  
Yutaka Takeda
Keyword(s):  
High Speed ◽  
Drilling Process ◽  
Printed Wiring Boards ◽  
Step Method ◽  
Processing Efficiency ◽  
High Productivity ◽  
Micro Holes ◽  
Drilling Quality ◽  
Micro Drilling ◽  
Drilling Conditions

A drilling technique using micro-drills of 0.2 mm or less in diameter and a super-high-speed spindle of 160000 rpm or more has been developed for drilling ultra-micro holes in printed wiring boards (PWBs). The drilling process requires higher reliability and quality to maintain the reliability of the electrical connection between circuit layers. On the other hand, higher processing efficiency is also required in PWBs manufacturing. To maintain high productivity, drilling is normally performed using a non-step method, but heat damage called B-RING occurs around the drilled holes with this method. To solve these problems without the loss of processing efficiency, we applied the rapid-feed step-drilling cycle method. We investigated the B-RING for drilling quality and evaluated the drilling time for processing efficiency under various drilling conditions. We found that using a rapid-feed step-drilling cycle with an appropriate number of steps and feed rates ensures a higher level of hole quality and processing efficiency compared with the conventional non-step drilling.

Sign in / Sign up

Export Citation Format

Share Document