Title

Modelling of microvia drilling with a Nd : YAG laser

Authors

Authors

C. Zhang; I. A. Salama; N. R. Quick;A. Kar

Comments

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Abbreviated Journal Title

J. Phys. D-Appl. Phys.

Keywords

OVERHEATED METASTABLE STATES; RADIATION; HOLES; VAPORIZATION; CERAMICS; POLYMERS; Physics, Applied

Abstract

Drilling of microvias with Nd:YAG laser of wavelength 1.06 mu m is studied for polymer materials used in high density electronic packaging applications. Generally thermal ablation is the dominant mechanism for such polymer materials in the nanosecond and microsecond laser pulse regimes. A transient thermal model is developed to describe the drilling process. Since a fraction of the laser energy is absorbed inside the polymer layer, volumetric heating occurs and an overheated small metastable region can form inside the layer. Thus the drilling mechanism involves thermal phase change, chemical decomposition and possibly explosion due to rapid thermal expansion and vaporization inside the polymer material. The volumetric heating can cause large thermal stresses inside the material, resulting in convex forms at the free surface of the substrate. Experimental results show the formation of such convex surfaces during laser irradiation. These surfaces eventually rupture and the material is removed explosively due to high internal pressures.

Journal Title

Journal of Physics D-Applied Physics

Volume

39

Issue/Number

17

Publication Date

1-1-2006

Document Type

Article

Language

English

First Page

3910

Last Page

3918

WOS Identifier

WOS:000239991000031

ISSN

0022-3727

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