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Method for a multihead laser drilling system

IP.com Disclosure Number: IPCOM000101717D
Publication Date: 2005-Mar-16
Document File: 4 page(s) / 25K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a multihead laser drilling system. Benefits include improved functionality, improved performance, improved throughput, and cost effectiveness.

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Method for a multihead laser drilling system

Disclosed is a method for a multihead laser drilling system. Benefits include improved functionality, improved performance, improved throughput, and cost effectiveness.

Background

              Conventionally, most laser drilling machines are single-head or dual-head machines. Their productivity is limited to a specific rate . The industry trend is decreasing via dimensions. However, CO2 laser  drilling productivity decreases as the dimensions decrease.

              Via positioning accuracy is another laser drilling issue. Most of the conventional efforts have been focused on modifying and changing the component of the laser drilling system. Modifications have proven useful to achieve about 33 % improvement in the alignment accuracy. However, to meet expected design rule requirements, an innovative change in the laser drilling system archeticture is required.

              Speeding up the laser-drilling process would increase the number of holes drilled per second. This change would increase the throughput and productivity of the laser drilling machine and reduce the cost of the laser drilling operation.

              As via dimensions decrease, an unwanted reduction in the drilling productivity occurs due to the difficulty of focusing the infrared beam of the CO2 laser down to the small via diameter currently projected on the substrate roadmaps. A method to speed up the laser drilling process and compensate for the throughput reduction is essential to ensure a cost-effective drilling operation.

              Improving the laser alignment accuracy would enable a decrease in the ratio between the capture pad and the via diameter. This change is required to increase routing density. Reducing the surface area occupied by the pad to the size that is only enough to compensates for the via-to-pad misalignment.

General description

      The disclosed method includes an apparatus that enables a faster laser drilling process with higher accuracy for via-to-pad alignment. A single laser generator produces a high-power laser beam that is split into two secondary beams. Each of the secondary beams is divided to four processing beams. Each processing beam is distributed among 4 galvanometer scanners, resulting in 16 drill operations being conducted simultaneously on 4 panels. Additionally, via-to-pad positioning accuracy is improved by minimizing the number of the X/Y table motions required to complete the drilling process on one panel.

      The key elements of the method include:

•             Generation of a primary high-power laser beam that can be divided into four individual processing beams

•             Division of the primary beam into various laser processing beams by using various optical elements

•             Synchronization of four independent galvo-scanner systems across one panel

•             Definition of the galvo-scan field and the X/Y table motion direction that minimize...