Smt Equipments (Pick And Place, Solder Paste Screen
SMT Equipments (Pick-and-Place, Solder Paste Screen Printer, Reflow Oven, Curing / Baking Oven, Repair and Inspection) By N.K.SHARMA www.logextechno.com
<ul><li>SMT Equipments </li></ul><ul><li>In SMT or Surface Mount Assemblies (all Three Types of Surface Mount – Type I, II, and III) have three major process steps in common: </li></ul><ul><ul><ul><li>mounting of electronic components , </li></ul></ul></ul><ul><ul><ul><li>soldering , and </li></ul></ul></ul><ul><ul><ul><li>cleaning. </li></ul></ul></ul><ul><li>A complete through-hole process and a surface mount process have nothing in common. </li></ul><ul><li>Following equipments are required for any SMT production line: </li></ul><ul><ul><ul><li>Solder paste printer </li></ul></ul></ul><ul><ul><ul><li>THM Inserter </li></ul></ul></ul><ul><ul><ul><li>SMD Placer </li></ul></ul></ul><ul><ul><ul><li>Adhesive Cure Oven </li></ul></ul></ul><ul><ul><ul><li>Reflow Oven </li></ul></ul></ul><ul><ul><ul><li>Cleaner </li></ul></ul></ul><ul><ul><ul><li>Wave Solder </li></ul></ul></ul>
Pick-and-Place Machine for SMT Pick-and-Place machine is the heart of surface mount. A pick-and-place machine picks and places electronic components onto the PCB prior to soldering. Pick-and-Place machines use vacuum pickup tools to hold the components. Few others also use vision-assisted alignment. In general, pick-and-place machines offer better speed, accuracy, and flexibility than through-hole insertion machines.
LS40V Pick and Place Machine with Vision Premium model with unmatched precision for low to medium production runs utilizing Cognex® Vision system. Automated Systems
This is a modular system built for growth. Stand alone or Inn-line 4800 CPH placement combined with flexibility and intelligence. The basic machine is complete except for the feeders and a PCB fixture. As soon as feeders are added to the package the machine is ready for production. In the basic configuration the MP-100 has one placement pipette, one component camera and one feeder bank. To increase the placement rate, component range or number of feeders the machine can be upgraded with an extra pipette, camera or feeder banks. This machine beats all competitors on price and performance and can be upgraded when needed.
Manual Systems MPP-21 Pick and Place System Efficient and accurate manual pick & place system with dispenser designed for low volume prototype and medium volume production runs. MPP-11 Pick and Place System Cost effective manual pick & place and dispenser system for short run and prototype assembly of printed circuit boards.
SMT Placement Machines Placement machines are the most critical and expensive pieces of equipment in SMT, which commonly constitute the bottleneck of the assembly line, and hence determine the throughput. Growing production volumes, reducing size of components and complexity of the boards reinforced the usage of full-automated assembly lines. Depending on the placement type, fully automated placement systems can be observed in two main groups: simultaneous and sequential placement equipment.
simultaneous placement systems , In simultaneous placement systems, the machine picks up and places all components at once, which requires the positioning of these components on a pattern before they are assembled. This method has been developed for producing PCBs including standard simple components in very large batch sizes. High production rates can be achieved with simultaneous placement, but it is not suitable for flexible automation due to long setup times and high level of customization.
Sequential assembly machines Sequential assembly machines work with so-called pick-and-place principle, i.e. pick every single component and then place it on the PCB in a sequential manner. These machines are more flexible and can assemble a wide range of components but do not reach the placement rates of simultaneous machines. There are also some special types of machines, which allow simultaneous pick up of multiple components and sequential placement of each on the PCB.
<ul><li>Another way to classify the placement equipment is by its design and functionality. In this study, placement machines are classified based on their working principles as following: </li></ul><ul><ul><ul><li>pick-and-place machines, </li></ul></ul></ul><ul><ul><ul><li>collect-and-place machines, </li></ul></ul></ul><ul><ul><ul><li>chip shooter, and </li></ul></ul></ul><ul><ul><ul><li>other forms of SMT machines </li></ul></ul></ul>
MATERIALS “ Three” important materials are involved in the SMD component placement process. Components, PCBs, solder paste or adhesive. Components A variation of dimensions, shapes and coloration of the components can play a role in the placement performance. Components that exceed the maximum or minimum tolerance set-up in the vision parameters will be rejected. Components from different vendors can have different colours and surface. This can cause problems in vision processing resulting in mis-alignment or rejection. PCBs The flatness of the PCBs and the solder land are both essential to the placement quality. If the PCBs are bend or twisted, the result can be mis-aligned components or missing components. Unequal height of HAL (Hot Air Leveling) of solder pads can result in mis-aligned components. The component leads will slide to the side and down from a too high solder pad. Unequal HAL layer can also cause mis-reading of fiducial marks. Solder paste / adhesive The tackiness and positioning accuracy of the solder paste or adhesive is essential to the placement quality. The solder paste or adhesive must hold the component in place until reflow soldered.
SMT (surface-mount technology) component placement systems, also called pick-and-place machines or P&Ps, are robotic machines which are used to place surface-mount devices (SMDs) onto a printed circuit board (PCB). They are used for high speed, high precision placing of broad range of electronic components, like capacitors, resistors, integrated circuits onto the PCBs which are in turn used in computers, telecommunications equipment, consumer electronic goods, industrial equipment, medical instruments, automotive systems, military systems and aerospace engineering. The systems, also commonly called 'pick and place' machines, normally use pneumatic suction nozzles, attached to a plotter-like device to allow the nozzle head to be accurately manipulated in three dimensions, and each nozzle can be rotated around its own axis.
Surface-mount components are placed along the front (and often back) faces of the machine. Most components, large and small are supplied on paper or plastic tape, the tape reels are loaded onto 'feeders', mounted to the machine. Larger ICs are sometimes supplied arranged in trays, which are stacked in a compartment on the machine for this purpose.
Through the middle of the machine there is a conveyor belt, along which unpopulated PCBs travel, and a PCB clamp in the centre of the machine. The PCB is clamped, and the nozzles pick up individual components from the feeders/trays, rotate them to the correct orientation and then place them on the appropriate pads on the PCB with a great deal of precision. Most Placement machines now can optically inspect components on picking, to ensure that the correct component has been picked, that it has been picked successfully and that it is in the correct rotational orientation. The components may be temporarily adhered to the PCB using the wet solder paste itself, or by using small blobs of a separate adhesive, applied by a glue dispensing machine.
PLACEMENT FACTORS When placing Surface Mount Components onto a PCB there are a lot of factors to consider. In the listing below the most essential factors are mentioned.
SMTrue Run Optimize Software Off-line programming and management software module for increased efficiency and throughput.
<ul><li>Features </li></ul><ul><li>Micro-table </li></ul><ul><ul><li>The micro-table clamps printed circuit boards as large as 297 mm x 420 mm (11.8" x 16.5"). A fine-adjustment capability and X and Y axis lockdowns make the ProtoPlace ideal for the placement of complex components. </li></ul></ul><ul><li>LCD Display </li></ul><ul><ul><li>Control and monitor the process via the 4-line LCD display. </li></ul></ul><ul><li>Keyboard </li></ul><ul><ul><li>The integrated multifunctional keyboard allows the direct selection of options, fine control of adjustments, and setting precise individuals parameters. </li></ul></ul><ul><li>Manipulator </li></ul><ul><ul><li>The manipulator picks & places components, and soldering with paste, glues and washers. The manipulator easily reaches every feeder (stick and tape feeders, turntable, or palette) by using vacuum and a picking needle. An additional manual control rotates components where needed and manual places components with only the touch of the needle. </li></ul></ul>
Semi-automatic placement of BGA components Product characteristics Placement of BGA and QFP components from 5 mm x 5 mm to 45 mm x 45 mm Granite base Air-bearing positioning table Inspection after placement
<ul><li>Dispenser </li></ul><ul><ul><li>This external unit dispenses soldering paste, glues, and washers from its mount directly on the manipulator. </li></ul></ul><ul><li>Air Regulator </li></ul><ul><ul><li>The air regulator regulates pressure during dispensing, vacuum during placement, and vacuum during dispensing. </li></ul></ul><ul><li>Software </li></ul><ul><ul><li>Each ProtoPlace includes user-friendly software designed to ease the operation and automation of component placement and paste dispensing. </li></ul></ul><ul><li>Foot Switch </li></ul><ul><ul><li>The integrated foot switch provides additional hands-free mode control to the user. </li></ul></ul>
Solder Paste Screen Printer for SMT A Solder Paste Screen Printer for SMT is needed to screen solder paste onto the printed circuit board (PCB) before placement of surface mount components. Solder Paste Printing Systems are available in three configurations: manual, semi-automatic and fully automatic. The machine can be table mounted, stand-alone, or in-line.
Reflow Soldering Equipment for SMT There are many reflow soldering methods and each method has advantages and disadvantages. The most widely used reflow processes in electronics are: vapor phase and infrared. A reflow soldering equipment / machine is the second major equipment after pick-and-place machine in any SMT line.
Curing / Baking Oven for SMT In electronics , an oven is required for both adhesive curing and solder paste baking operations. The same or different ovens may be used for adhesive curing and baking of solder paste. If an Infrared (IR) oven or a convection oven is used for reflow soldering, it is not necessary to have separate adhesive and solder paste baking ovens. The same IR or convection oven can be used for adhesive curing, solder paste baking, and reflow soldering.
Wave Soldering Equipment The need for wave soldering equipment can also be met by simply retrofitting the conventional solder pot with dual pot – at a small fraction of the cost of a new machine. A completely new machine is not necessary
Solvent Cleaning in SMT In SMT, the cleaning process has received considerable attention because of efforts to eliminate chlorofluorocarbons (CFCs) and other ozone depleting chemicals. The subjects of flux, solder and cleaning are closely intertwined. The selection of solvent and cleaning equipment depends of the flux used and the cleanliness requirements
Repair and Inspection Equipment for SMT Equipment unique to surface mounting includes inspection and repair / rework equipment. There are two main types of automated inspection equipment for SMT on the market: x-ray and laser. Repair / Rework equipment include: conductive tips or hot air for removal and replacement of components, conductive tips with built-in heating elements, hot air repair / rework tools.
SMT Repair and Inspection Equipment Equipment unique to surface mounting includes inspection and repair / rework equipment. Inspection equipment for surface mounting in electronics has not matured yet. There are two main types of automated inspection equipment on the market: x-ray and laser. However, most electronic companies depend on visual inspection at 2 to 10X, using either microscope of magnifying lamp.
Repair / Rework equipment and electronic PCB assembly tools and equipments use conductive tips or hot air for removal and replacement of components. Conductive tooling, such as soldering iron tip attachments, is very inexpensive. The tips come in different configurations for different electronic components but have limited applications. At a slightly higher cost, there are other conductive tips with built-in heating elements. At a much higher cost, hot air repair / rework tools are available that use nozzles of different sizes for components of different types and sizes. The hot air repair tooling is most commonly used for surface mounting in SMT because it is ideal for damage-free repair.
AM-1A Complete Rework Station SMD Rework Station for rework and repair of through-hole and SMT boards. It contains 4 modules which cover the main rework tasks. Optional Micro Hot Tweezers and Standard Hot Tweezers are available with numerous cartridges. Standard Hot tweezers can also be used for wire stripping. Hot air for desoldering any size of SMD components. The station uses the exclusive JBC system, based on protectors-extractors (See image at bottom of page) and hot-air flow, which makes desoldering clean and quick, concentrating the heat on the IC, and protecting the rest of the circuit at the same time. A medium-sized SMD can be desoldered in less than 20 seconds. When the IC is at desoldering temperature the extractor snaps the IC upward so fast that the leads are almost completely devoid of solder. This makes replacement of the same IC very easy if you wish. Desoldering SMTs, through hole components and cleaning of through-hole components and pads by using the desoldering iron DR 5600 , which contains an independent vacuum pump. Pick & Place vacuum pen to aid in positioning components. Soldering of all types of components, with the swift response, power and temperature recovery
End of part I (SMT) By N.K.SHARMA www.logextechno.com