Face-Up Chip Mounting Alignment with Dual-Focus Mark Recognition
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Solution Overview
Problem
Existing face-up mounting devices struggle with achieving high-precision alignment on the submicron level due to variations in straightness when the mounting head descends, leading to errors in the alignment to mounting transition. Additionally, the complexity of reflective optical systems increases costs and complicates the alignment process.
Innovation Solution
A mounting device with independently provided chip and substrate recognition imaging means, allowing for simultaneous recognition of marks through a shared optical axis path with different focal positions. This device includes a control unit that calculates positional deviations and performs alignment by driving the mounting head and/or substrate stage, ensuring accurate alignment within a single depth of field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reflective optical system is used to recognize chip and substrate recognition marks, then alignment recognition is enabled, but the optical path lengths differ due to height differences between marks, making it difficult to acquire high-resolution images simultaneously
Solution Approach 1:
The patent introduces a beam splitter as an intermediary optical element that divides the optical path into two separate paths. This allows independent focusing for chip and substrate recognition marks at different heights while sharing a common illumination source and detection system, resolving the depth of field conflict without requiring separate imaging systems
Solution Approach 2:
The optical system is segmented into multiple independent imaging channels, each with its own focal plane. The chip recognition imaging unit focuses on the chip surface while the substrate recognition imaging unit focuses on the substrate surface, allowing simultaneous high-resolution imaging of both marks despite their height difference
2Productivity
If the mounting head descends from alignment height to mounting height, then mounting is completed, but straightness variations cause alignment errors
Solution Approach 1:
The patent replaces mechanical alignment methods with optical field-based alignment using recognition marks and imaging systems. This allows alignment to be performed optically at the mounting head position without relying on mechanical straightness, as the recognition mechanism can detect and compensate for positional deviations
Solution Approach 2:
The system changes the alignment parameter from mechanical position to optical image coordinates. By capturing images of recognition marks and calculating positional deviations in the image plane, the system can achieve high-precision alignment independent of mechanical straightness variations during head descent
3Measurement precision
If recognition marks are made on the electrode surface side for clear relative position reference, then alignment reference is improved, but the height difference between chip and substrate marks increases, complicating the optical system
Solution Approach 1:
The patent makes the recognition marks serve dual functions: they provide clear relative position reference for alignment while also being positioned at different heights to enable independent focusing. The marks are designed to be recognizable by the imaging system regardless of their vertical separation, eliminating the need for complex reflective optical paths
Data Source
AI summary
A mounting device comprises a substrate stage, a mounting head, an elevating unit, a recognition mechanism, and a control unit. The recognition mechanism acquires position information about a chip recognition mark and a substrate recognition mark using an imaging unit. The control unit calculates an amount of positional deviation between a chip component and a substrate from the position information about the chip recognition mark and the substrate recognition mark, and performs alignment by driving the mounting head and/or the substrate stage according to the amount of the positional deviation. The chip component and the substrate are brought closer with each other and the alignment is performed in a state in which the imaging unit simultaneously images the chip recognition mark and the substrate recognition mark within a depth of field, after which the chip component and the substrate are brought into close contact with each other.