Quality Estimating Model Based on Temperature of Hole Bottom in Laser Drilling of Blind Holes

2003 ◽  
Author(s):  
Eiichi Aoyama ◽  
Hisaya Kondou ◽  
Ryu Minagi ◽  
Tsutao Katayama ◽  
Toshiki Hirogaki ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Copper Foil ◽  
Thermal Stresses ◽  
Present Report ◽  
Laser Drilling ◽  
Core Material ◽  
Foil Surface ◽  
Printed Wiring Board ◽  
Heat Damage ◽  
Suitable Material

The printed wiring board (PWB) has becomes relatively smaller due to the downsizing of electric devices. Higher densification has been advanced by the circuit formation of multi-layer PWBs in the current manufacturing of these boards. In current manufacturing of multi-layer printed wiring boards, a method frequently used is to laminate the core with insulating resin as build-up layers. Microvia drilling using laser technology has become the prevailing method of machining smaller blind via holes. Aramid fiber reinforced plastic (AFRP) is considered suitable material for the build-up layers, because it is efficient in laser drilling. However, heat damage in the hole has been a problem because the laser drilling cause a heat damage to the PWB materials. The poor hole quality, such as the carbonization of the resin and the peel around circuit copper foil/core material, causes decrease in the reliability of circuit connections. In the present report, first, we took multi layer PWB-reinforced by aramid unwoven cloth, and measured the temperature distribution of the circuit copper foil during laser drilling using a thermocouple. Second, we proposed a heat input prediction model using a finite element method (FEM), considering the change of laser absorption of the circuit copper foil surface. Finally, we carried out a thermal stress analysis based on the temperature distribution, and confirmed the efficiency of this analysis. As a result, the calculated temperatures by this model, considering the variation of the absorption of foil surface during laser drilling, are in good agreement with the experimental temperatures. It is confirmed that this model is effective in estimating the temperatures and thermal stresses in the bottom copper foil during laser drilling of the build-up layers.

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.

Coupled Thermal-Structural Analysis of Generator For sCO2 Turbomachinery

2021 ◽  
Author(s):  
Ramesha Guntanur ◽  
Ashutosh Patel ◽  
Vijay Biradar ◽  
Pramod Kumar
Keyword(s):  
Thermal Analysis ◽  
Finite Element ◽  
Temperature Distribution ◽  
Structural Analysis ◽  
Contact Pressure ◽  
Temperature Rise ◽  
Thermal Stresses ◽  
Flow Path ◽  
Heat Losses ◽  
Positive Contact

Abstract This paper presents the coupled thermal and structural analysis of the rotating components of the generator using ABAQUS finite element solver. The interference between shaft and rotor is optimized to have a positive contact pressure and also minimize the stresses in the laminate at all operating speeds. Thermal analysis is performed to simulate the temperature distribution arising from the heat losses of generator. The flow path of the coolant is designed through the shaft to minimise the temperature rise of the generator. The resulting changes in the contact pressure between laminated disc and shaft is computed using sequentially coupled thermal and structural analysis. The thermal stresses of rotor are computed estimated and the design is optimized for transmitting torque at different operating speeds.

Research Status of Copper Foil Surface Treatment and Development of Novel Process

2017 ◽  
Vol 727 ◽  
pp. 43-51
Author(s):  
Wen Jing Wang ◽  
Xue Feng Liu
Keyword(s):  
Surface Treatment ◽  
Future Development ◽  
Copper Foil ◽  
Science Research ◽  
Research Progress ◽  
Foil Surface ◽  
Research Status ◽  
New Process ◽  
The Future ◽  
Brush Plating

Surface treated copper foil and its preparation is very important and widely used. The science research and enterprise competition always focus on the surface treated methods in the copper foil field. This paper summarized the typical surface treated processes of copper foil, and emphasized on research progress and problems of copper foil surface treated processes. The brush plating-dealloying treated process of copper foil was proposed based on the problems. The principle and research status of new process was introduced. At last, the future development of surface treated process and application prospect were forecast.

scholarly journals Determination of temperature and thermal stresses distribution in power boiler elements with use inverse heat conduction method

2011 ◽  
Vol 32 (3) ◽  
pp. 191-200 ◽  
Author(s):  
sławomir Grądziel
Keyword(s):  
Boundary Condition ◽  
Heat Conduction ◽  
Temperature Distribution ◽  
Thermal Stresses ◽  
Thermal Boundary Condition ◽  
Transient Temperature ◽  
Inverse Heat Conduction ◽  
Transient Temperature Distribution ◽  
Power Boiler

Determination of temperature and thermal stresses distribution in power boiler elements with use inverse heat conduction method The following paper presents the method for solving one-dimensional inverse boundary heat conduction problems. The method is used to estimate the unknown thermal boundary condition on inner surface of a thick-walled Y-branch. Solution is based on measured temperature transients at two points inside the element's wall thickness. Y-branch is installed in a fresh steam pipeline in a power plant in Poland. Determination of an unknown boundary condition allows for the calculation of transient temperature distribution in the whole element. Next, stresses caused by non-uniform transient temperature distribution and by steam pressure inside a Y-branch are calculated using the finite element method. The proposed algorithm can be used for thermal-strength state monitoring in similar elements, when it is not possible to determine a 3-D thermal boundary condition. The calculated temperature and stress transients can be used for the calculation of element durability. More accurate temperature and stress monitoring will contribute to a substantial decrease of maximal stresses that occur during transient start-up and shut-down processes.

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