SMT工艺知识讲义（英文版）(ppt 67页)

SMT工艺知识讲义（英文版）内容提要：
Considerations for Placement - Board Size
Equipment adjusts to min/max PCB or panel size for various SMT products
In-line conveyor fixturing is utilized
Edge margin requirements must be designed into PCB or panel
Thickness of PCB is process consideration
Work envelope needs to include PCB size, feeders, and placement
Fiducials on PCB are used by camera and computer for accurate placement
Considerations for Placement - Components
Each placement tool usually handles a range of component sizes
Vacuum nozzle size defined by dimensional range of components
Z-strokes refers to component movement in up-down locations
Component alignment on pick-up head utilizes vision
Chips: outline & centroid
IC’s: centroid, individual leads, coplanarity, etc.
Component verification is done “on the fly”, checking for correct component values
Equipment detects missing parts

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