Wiring Board Alignment Mark Structure for Accurate CCD Reading
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Solution Overview
Problem
Existing wiring boards face challenges in accurately aligning upper layers with lower layers due to reading errors in alignment marks, particularly when using charged coupled device (CCD) cameras for image recognition, as the alignment marks are prone to errors from filler aggregation during laser processing.
Innovation Solution
The alignment mark is designed with a metal pattern and a first resin pattern that includes a central region covered by a first resin region and exposes portions of an outer region, reducing the need for extensive laser processing and minimizing filler aggregation, thereby enhancing readability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the alignment mark is formed with extensive laser processing to expose the metal pattern, then the alignment mark becomes visible for reading, but filler aggregation occurs during laser processing which causes reading errors
Solution Approach 1:
The patent converts the harmful effect of filler aggregation during laser processing into a beneficial design feature. Instead of attempting to completely eliminate filler presence, the design accepts that filler will aggregate in the outer region during laser processing, and deliberately structures the alignment mark so that the critical central region remains clear of filler. The filler aggregation in the outer region is tolerated as it does not interfere with the readable central portion, thus converting a processing defect into a non-critical feature.
Solution Approach 2:
The alignment mark is segmented into a central region and an outer region with distinct functions. The central region is designed to be primarily covered by the resin pattern with minimal laser processing, ensuring it remains free of filler aggregation and maintains high readability. The outer region accepts extensive laser processing and filler aggregation, serving as a sacrificial zone that protects the central region from the harmful effects of the laser process.
2Ease of manufacture
If the outer region of the metal pattern is extensively exposed through laser processing, then the alignment mark structure is completed, but filler aggregates during processing which reduces measurement precision
Solution Approach 1:
The resin pattern serves as an intermediary protective layer between the laser processing and the metal pattern's central region. During laser processing, the resin pattern is selectively removed from the outer region while maintaining coverage over the central region. This intermediary approach allows the laser to process the outer region and form the alignment mark structure while protecting the central region from filler aggregation, thus enabling easy manufacture without sacrificing measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed alignment mark design reduces reading errors by preventing filler aggregation and improving visibility of the alignment mark edges, ensuring accurate alignment without delamination.
Implementation Method 1
The alignment mark is optically read by a charged coupled device (CCD) camera or the like to perform an image recognition
Implementation Method 2
the first resin pattern includes a first region covering the central region, and a second region covering a portion of the outer region and exposing other portions of the outer region
Data Source
AI summary
A wiring board includes an interconnect layer including a metal pattern, and an insulating layer, disposed on the interconnect layer, and including a first resin pattern. The insulating layer includes a filler. The metal pattern includes a central region, and an outer region located on an outer periphery of the central region. The first resin pattern includes a first region covering the central region, and a second region covering a portion of the outer region and exposing other portions of the outer region. The metal pattern and the first resin pattern constitute an alignment mark.