Surface Mount Inspection Using Actual Land Position Reference
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Solution Overview
Problem
Existing inspection techniques in surface mounting lines rely on design values for positional deviation inspections, which are unreliable when actual land positions deviate from their design values due to manufacturing errors or warping, leading to false positives or negatives.
Innovation Solution
The system determines the position of elements other than the land, such as wiring patterns, to accurately estimate the land position, using template matching and positional relationship information generated from sample boards, allowing for accurate land position determination even when lands are hidden under solder or components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If design values from CAD data are used as reference for positional deviation inspection, then the inspection process is simple and fast, but the inspection accuracy deteriorates when actual land positions deviate from design values due to manufacturing errors or board warping
Solution Approach 1:
The system performs preliminary action by capturing a board image before the inspection process and detecting land positions from this pre-captured image. The land position detection unit extracts actual land positions from the board image in advance, storing them for subsequent inspection processes. This preliminary detection of actual land positions eliminates the need to use inaccurate design values as reference during inspection, thereby resolving the contradiction between inspection speed and accuracy.
2Measurement precision
If actual land position is used as reference for inspection, then the inspection accuracy is improved, but the difficulty of detecting and measuring increases because the land may be hidden under solder or components
Solution Approach 1:
The system performs preliminary action by capturing a board image before the inspection process and detecting land positions from this pre-captured image. The land position detection unit extracts actual land positions from the board image in advance, storing them for subsequent inspection processes. This preliminary detection of actual land positions eliminates the need to use inaccurate design values as reference during inspection, thereby resolving the contradiction between inspection speed and accuracy.
Solution Approach 2:
The inspection system is segmented into distinct functional units: a board image capturing unit that captures the board image, a land position detection unit that detects land positions from the captured image, and an inspection unit that performs positional deviation inspection using the detected land positions as reference. This segmentation allows the land position detection to be performed separately before inspection, overcoming the difficulty of detecting hidden lands during the inspection process itself.
3Measurement precision
If the land area is separated from solder area in captured image to restore hidden land area, then the land position can be determined, but the technique is inapplicable when land is hidden almost entirely under solder or component
Solution Approach 1:
The system performs preliminary action by capturing a board image before the inspection process and detecting land positions from this pre-captured image. The land position detection unit extracts actual land positions from the board image in advance, storing them for subsequent inspection processes. This preliminary detection of actual land positions eliminates the need to use inaccurate design values as reference during inspection, thereby resolving the contradiction between inspection speed and accuracy.
Data Source
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Figure 3A~3B
AI summary
A technique enables an inspection using an actual land position as a reference in a surface mounting line. An inspection apparatus includes an imaging unit that captures an image of a board having a land on which a solder piece has been printed, an image of the board having a component mounted on the solder piece, or an image of the board having the component soldered to the land, a land determination unit that determines a position of an element on the board other than the land from the image of the board captured by the imaging unit, and determines a positon of the land in the image based on the determined position of the element, and an inspection unit that inspects the solder piece or component on the land using the position of the land determined by the land determination unit as a reference.