Circuit Board Recognition Mark Layout for Accurate Chip Mounting
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Solution Overview
Problem
Conventional circuit boards face challenges in accurately identifying recognition marks due to partial hiding by the solder resist layer, leading to potential misidentification of pads as recognition marks, especially when the opening shape is not circular and the dimensional ratio of the opening is unstable, affecting the accuracy of semiconductor chip mounting.
Innovation Solution
A circuit board design featuring a recognition mark with a circular shape exposed through a through-hole of variant shape, where the through-hole includes a circular first through-hole and a semi-circular second through-hole, ensuring the entire upper surface of the recognition mark is exposed and easily recognizable, even when the shape is not perfectly circular.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the opening shape is circular and the recognition mark is exposed, then the recognizability of the recognition mark is improved, but the dimensional ratio of the opening becomes unstable when the opening shifts
Solution Approach 1:
The patent introduces an asymmetric second opening that extends in a specific direction from the circular first opening. This asymmetric design provides a reference direction that remains stable even when the entire opening structure shifts, allowing the mount device to accurately identify the recognition mark's position and orientation without being affected by dimensional ratio changes
2Measurement precision
If the opening is perfectly circular to match the pad shape, then the recognizability is improved, but the mount device may mistakenly identify the recognition mark as a pad
Solution Approach 1:
The asymmetric second opening breaks the circular symmetry of the first opening, creating a unique shape that cannot be confused with the circular pad. This asymmetric feature serves as a distinctive identifier that allows the mount device to reliably distinguish the recognition mark from pads, eliminating misidentification while maintaining high recognizability
3Reliability
If the opening shape is variant (non-circular) to prevent misidentification, then the reliability of identification is improved, but the recognizability of the recognition mark deteriorates
Solution Approach 1:
The opening is segmented into two distinct parts: a circular first opening that provides high recognizability and a directional second opening that provides asymmetric identification features. This segmentation allows each part to fulfill its specific function - the circular portion ensures easy recognition while the asymmetric portion prevents misidentification, achieving both high recognizability and reliability simultaneously
Data Source
AI summary
A circuit board includes an interconnect and an insulating layer that covers the interconnect. The interconnect includes a first interconnect that is formed to serve as a recognition mark of which planar shape is a predetermined shape. The insulating layer has a through-hole of which planar shape is variant and that penetrates the insulating layer in a thickness direction of the insulating layer such that an entire upper surface of the first interconnect is exposed. The through-hole includes a first through-hole of which planar shape is a predetermined shape and that penetrates the insulating layer in the thickness direction such that the entire upper surface of the first interconnect is exposed and a second through-hole that serves as part of an inner wall surface of the first through-hole and that penetrates the insulating layer in the thickness direction.