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Method for laser trimming of etch-resistive material for localized fine-feature patterning

IP.com Disclosure Number: IPCOM000032214D
Publication Date: 2004-Oct-26
Document File: 3 page(s) / 137K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for laser trimming of etch-resistive material for localized fine-feature patterning. Benefits include improved functionality and improved yield.

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Method for laser trimming of etch-resistive material for localized fine-feature patterning

Disclosed is a method for laser trimming of etch-resistive material for localized fine-feature patterning. Benefits include improved functionality and improved yield.

Background

      Increased product density is driving board features to less than 0.003 inch for printed circuit boards (PCBs) and package designs for localized usage.

      Inner-layer line widths are typically created using a conventional resist, expose, develop, and etch process. As line widths are reduced (less than 0.003 inch) the resist application, which defines the line width, becomes increasingly critical. As the width of the resist material is reduced, the resist has a greater propensity to loose adhesion and flake-off during development. The result is inferior resolution on the sub-0.003-inch lines, resulting in low yield on inner layers and higher board cost.

      An option to the conventional process is full resist removal by laser ablation, but this is inefficient and a costly process when large features are combined with fine features. Full resist removal by laser ablation is available but not utilized in PCB industry due to the reduced factory throughput.

      Each print develop process has a minimum feature capability. Reducing the feature size on any portion within a working area requires a complete change of the print development process.

              With conventional inner-layer processing, the fabricator applies the resist material to the copper areas to be imaged. The inner layer is imaged or exposed at ~0.004-inch width. The full inner layer is developed using a sodium carbonate spray process. The typical etch process is performed.

General description

      The disclosed method is the laser trimming of developed resist material to create fine features on inner layers.

              The key elements of the method inc...