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.

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.

Cu-Direct Laser Drilling of Blind Via-Hole in Multi-Layer PWBs: Influence of Surface Treatment on Drilled Hole Quality

2009 ◽  
Author(s):  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
Keiji Ogawa ◽  
Tsukasa Ayuzawa
Keyword(s):  
Surface Treatment ◽  
Co2 Laser ◽  
Copper Foil ◽  
Laser Energy ◽  
Copper Surface ◽  
Laser Drilling ◽  
Hole Quality ◽  
Direct Laser ◽  
Overhang Length ◽  
Direct Drilling

This report describes the quality assessment of Blind Via Holes (BVHs) of Printed Wiring Boards (PWBs) drilled by a CO2 laser using Cu-direct drilling. In the Cu-direct drilling method, the copper foil and the build-up layer are melted at the same time, and the surface is treated to increase the laser energy absorbed by the copper foil since an untreated copper surface reflects most of the 10.6-μm-wavelength CO2 laser beam. However, there are few reports dealing with Cu-direct laser drilling of PWBs. In addition, when copper and resin with different processing thresholds are drilled at the same time, occurrences of a defect called overhang have been observed. So, in this report, first we propose a new method using thermography to measure the absorptance of a PWB surface for a CO2 laser. Moreover, we investigate how surface treatment of the outer copper foil influences the quality of a laser-drilled hole. Then, we observe the circumference of a point irradiated with the CO2 laser and explain how melting processes are different from surface treatment. Finally, based on the research we establish a method in order to cut down the overhang length as a parameter of drilled-hole quality. We also show that a high absorptance improves BVH quality.

scholarly journals Evaluation of Blind Via Hole Quality on Multi-Layer Printed Wiring Boards by Cu Direct Laser Drilling

2006 ◽  
Vol 55 (3) ◽  
pp. 335-340 ◽  
Author(s):  
Toshiki HIROGAKI ◽  
Eiichi AOYAMA ◽  
Keiji OGAWA ◽  
Ryu MINAGI ◽  
Toshiki MURAKAMI ◽  
...  
Keyword(s):  
Laser Drilling ◽  
Printed Wiring Boards ◽  
Hole Quality ◽  
Direct Laser ◽  
Via Hole

scholarly journals Highly Reliable CO2 Laser VIA Hole Drilling Technology by In-site Process Monitoring

2012 ◽  
Vol 15 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Ken-ichiro Tanaka ◽  
Masao Kubo ◽  
Yuichi Uchida ◽  
Isamu Miyamoto
Keyword(s):  
Process Monitoring ◽  
Co2 Laser ◽  
Hole Drilling ◽  
Drilling Technology ◽  
Via Hole

Influence of Cu Surface Treatment on the Cu-Direct Via Hole Drilling Efficiency of PWBs

2007 ◽  
Author(s):  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
Keiji Ogawa ◽  
Shogo Matsutani
Keyword(s):  
Laser Beam ◽  
Surface Treatment ◽  
Co2 Laser ◽  
Copper Foil ◽  
Copper Surface ◽  
Surface Shape ◽  
Hole Drilling ◽  
Black Oxide ◽  
Direct Drilling ◽  
The Relationship

This report describes the quality assessment of blind via holes (BVHs) of Printed Wiring Boards (PWBs) drilled by a CO2 laser using Cu-direct drilling. In the Cu-direct drilling method, the copper foil and the buildup layer are melted at the same time, and the surface is treated to increase the laser energy absorbed by the copper foil because an untreated copper surface reflects most of the 10.6-μm-wavelength CO2 laser beam. We used black-oxide and V-bond treatments as surface treatment. Previously, the only black-oxide treatment was paid attention to, but the new V-bond treatment is also investigated in this report. First, a straightforward method employing infrared thermography was proposed to determine the absorbance of the CO2 laser beam by the copper surface. Then, we used SEM to characterize the copper surfaces after surface treatment, and established the relationship between laser absorbance and surface shape. Subsequently, we observed the circumference of a point irradiated with the CO2 laser and explained melting processes were different from surface shape. Finally, we investigated the relationship between laser absorbance and BVH quality, and showed that a high absorbance improved BVH quality.

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