【正文】 LOGO SMT工藝 10 SMT PROCESS TRAINING 10 Introduction, Technology Trends, Assembly Types and SMT Component Technologies LOGO Module 4 – Unit 3 Placement Considerations and Flexibility 3 Considerations for Placement Board Size ? Equipment adjusts to min/max PCB or panel size for various SMT products ? Inline 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 puter for accurate placement 4 Considerations for Placement Components ? Each placement tool usually handles a range of ponent sizes ? Vacuum nozzle size defined by dimensional range of ponents ? Zstrokes refers to ponent movement in updown locations ? Component alignment on pickup head utilizes vision ? Chips: outline centroid ? IC’s: centroid, individual leads, coplanarity, etc. ? Component verification is done “on the fly”, checking for correct ponent values ? Equipment detects missing parts 5 Considerations for Placement Feeders ? Complexity of changeover of feeders is process consideration ? Number of feeders required equals number of different ponents in bill of materials ? Feeder must be patible with ponent packaging from vendor ? Tape cover peelback capabilities built into feeders ? Ease of loading pin locators and electrical connections affect process time ? Operator awareness necessary for feeder selection accuracy 6 Component Placement System ? Flexibility ? The wider the variety of ponents a machine can place, the more flexible it is ? Most mon feeder types: ? Tape and reel ? Bulk ? Matrix trays and waffle packs ? Magazines or tubes ? Vibratory feeders ? Surf tape ? Direct Die feeder 7 Tape and Reel ? Preferred for large quantity production ? Ability to hold large quantities of parts ? Lower downtime required for reloading ? Controlled Orientation and position for parts ? Lot number traceability control ? The tape is available in varying widths ranging from 8 mm to 72 mm ? The ponent carrier in tape is made of punched cardboard or thermoformed plastic ?Suitable for passive ponents, discrete actives, SOJs, PLCCs, SOICs, Standard pitch QFPs, Bare Dies, BGAs other SMDs that do not have fragile leads 8 Siemens: 3x8 mm Feeder 0201 ? 3x8 mm Feeder ?golden edition“ specialized for 0201 and 0402 ? Increased accuracy / repeatability ? No tape shutter, eliminates mechanical influence on the ponent 3x8 mm Standardfeeder Tape shutter 3x8 mm Feeder ?Golden edition“ Fixed tape removal edge 9 Bulk Packaging ? Pros ? Small, no waste ? High capacity ? Fast refill ? Cons ? New feeders required ? New ponent reference number ? Possible damage to end terminations 10 Matrix Tray and Waffle Pack ? These are useful for smaller production runs with customized products ? Largely used for Integrated Circuit packages ?Available in sizes of 2” x 2” and larger For Fine Pitch QFPs, BGAs, etc. For Bare Dies CSPs 11 Suitable for SOICs, SOJs PLCCs Feeder Tubes ? Both flexible and rigid sticks are available for several sizes of integrated circuits and other ponents ?A reasonable number of devices can be handled in each stick ? The parts will remain oriented and protected, once loaded 12 Vibratory Feeders Feeder Tubes Source: US VIBRA, Inc. 13 Surf Tape ? A pressuresensitive sticky tape fixed to the base of the punched plastic carrier ? Components adhere with their backside to the sticky tape ? No cover tape is used ? Used for bare dies and flip chips ? Flip chips have to be flipped inside the feeder 14 Source: Chip Scale Review Direct Die Feeder 15 Smart Feeders 16 Retrofitable Smart Feeder Utilizing RFID 17 Programming 18 Vision System LOGO Module 4 – Unit 3 Pick and Place Process Steps 20 Pick and Place Process Steps ? Step 1 ? Boards from the screen print operation move into the Pick and Place ? SMT lines may utilize 1 or more Pick and Place machines to populate PCBs ? The Pick and Place assembles large and small SMT ponents onto the printed circuit board (PCB) with correct orientation, polarity and placement location ? Step 2 ? Components are loaded onto the Pick and Place using feeders ? Step 3 ? The Pick and Place is controlled by software, using a puter mouse and monitor ? Step 4 ? A vision system verifies the PCB is aligned properly in the Pick and Place, using fiducial markings Software, monitor and mouse Component Placement Feeder Fiducials 21 Pick and Place Process Steps ? Step 5 ? Nozzles “pick up” and “place” ponents ? Step 6 ? A camera takes a