Pick-and-place machine
Robotic machine
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Internal details of a two head, gantry style pick-and-place JUKI SMT machine. In the foreground are tape and reel feeders, then the (currently empty) conveyor belt for printed circuit boards, and in back are large parts in a tray. The gantry carries two pickup nozzles, flanking a camera (marked "do not touch" to avoid fingerprints on the lens).
Tape-and-reel feed mechanism used to load components into a pick-and-place machine
SMD pick-and-place machine (with simulated motion blurs)
Surface-mount technology (SMT) component placement systems, commonly 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 a broad range of electronic components (such as capacitors, resistors, and integrated circuits) onto the PCBs which are in turn used in computers, consumer electronics, and industrial, medical, automotive, military and telecommunications equipment. Similar equipment exists for through-hole components.[1][2]
This type of equipment is sometimes used to package microchips using the flip chip method.
History
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During this time, a typical SMT assembly line employed two different types of pick-and-place (P&P) machines arranged in sequence.
The unpopulated board was fed into a rapid placement machine. These machines, sometimes called chip shooters, place mainly low-precision, simple package components such as resistors and capacitors. These high-speed P&P machines were built around a single turret design capable of mounting up to two dozen stations. As the turret spins, the stations passing the back of the machine pick up parts from tape feeders mounted on a moving carriage. As the station proceeds around the turret, it passes an optical station that calculates the angle at which the part was picked up, allowing the machine to compensate for drift. Then, as the station reaches the front of the turret, the board is moved into the proper position, the nozzle is spun to put the part in the proper angular orientation, and the part is placed on the board. Typical chip shooters can, under optimal conditions, place up to 53,000 parts per hour, or almost 15 parts per second.[citation needed]
Because the PCB is moved rather than the turret, only lightweight parts that will not be shaken loose by the violent motion of the PCB can be placed this way.
From the high speed machine, the board transits to a precision placement machine. These pick-and-place machines often use high resolution verification cameras and fine adjustment systems via high precision linear encoders on each axis to place parts more accurately than the high-speed machines. Furthermore, the precision placement machines are capable of handling larger or more irregularly shaped parts such as large package integrated circuits or packaged inductor coils and trimpots. Unlike the rapid placers, precision placers generally do not use turret mounted nozzles and instead rely on a gantry-supported moving head. These precision placers rely upon placement heads with relatively few pickup nozzles. The head sometimes has a laser identifier that scans a reflective marker on the PC board to orient the head to the board. Parts are picked up from tape feeders or trays, scanned by a camera (on some machines), and then placed in the proper position on the board. Some machines also center the parts on the head with two arms that close to center the part; the head then rotates 90 degrees and the arms close again to center the part once more. The margin of error for some components is less than half a millimeter (less than 0.02 inches). [citation needed]
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Due to the huge cost of having two separate machines to place parts, the speed limitations of the chip shooters, and the inflexibility of the machines, the electronic component machine manufacturers abandoned the technique. To overcome these limitations they moved to all-in-one modular, multi-headed, and multi-gantry machines that could have heads quickly swapped on different modules depending on the product being built to machines with multiple mini turrets capable of placing the whole spectrum of components with theoretical speeds of 136,000 components an hour. The fastest machines can have speeds of up to 200,000 CPH (components per hour).[3]
onwards
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Swapping heads onboard placement machines required more inventory of heads and related spare parts for different heads to minimize the downtime. Placement machines have an all-in-one head that can place components ranging from 0.4 mm × 0.2 mm to 50 mm × 40 mm.
In addition to this there was a new concept wherein the user could borrow performance during peak periods.
There is a big change in the industry approach these days with more focus on software applications for the process. With new applications like POP and wafer placement on substrate the industry is moving beyond conventional component placement.
There is a big difference in the needs of SMT users. For many, the high speed machines are not suitable due to cost and speed. With recent changes in the economic climate the requirement for SMT placement becomes focused on the machine's versatility to deal with short runs and fast changeover.[citation needed] This means that lower cost machines with vision systems provide an affordable option for SMT users. There are more users of low end and mid-range machines than the ultra fast placement systems.[citation needed]
Operation
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The placement equipment is part of a larger overall machine that carries out specific programmed steps to create a PCB assembly. Several sub-systems work together to pick up and correctly place the components onto the PCB. These systems normally use pneumatic suction cups, attached to a plotter-like device to allow the cup to be accurately manipulated in three dimensions. Additionally, each nozzle can be rotated independently.
Component feeds
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Surface mount components are placed along the front (and often back) faces of the machine. Most components are supplied on paper or plastic tape, in tape reels that are loaded onto feeders mounted to the machine. Larger integrated circuits (ICs) are sometimes supplied and arranged in trays which are stacked in a compartment. More commonly used ICs will be provided in tapes rather than trays or sticks. Improvements in feeder technology mean that tape format is becoming the preferred method of presenting parts on an SMT machine.
Early feeder heads were much bulkier, and as a result, it was not designed to be the mobile part of the system. Rather, the PCB itself was mounted on a moving platform that aligned the areas of the board to be populated with the feeder head above.[4]
Conveyor belt
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Through the middle of the machine there is a conveyor belt, along which blank PCBs travel, and a PCB clamp in the center 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 high precision. High-end machines can have multiple conveyors to produce multiple same or different kinds of products simultaneously.
Inspection and visual system
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The part being carried from the part feeders on either side of the conveyor belt to the PCB, it is photographed from below by using high resolution camera and a lighting system. Its silhouette is inspected to see if it is damaged or missing (was not picked up), and the inevitable registration errors in pickup are measured and compensated for when the part is placed. For example, if the part was shifted 0.25 mm and rotated 10° when picked up, the pickup head will adjust the placement position to place the part in the correct location.
Some machines have these optical systems on the robot arm and can carry out the optical calculations without losing time, thereby achieving a lower derating factor.
The high-end optical systems mounted on the heads can also be used to capture details of the non-standard type components and save them to a database for future use. In addition to this, advanced software is available for monitoring the production and interconnect database &#; of the production floor to that of supply chain &#; in real-time. ASM provides an optional feature for increasing accuracy while placing LED components on a high end product where in the optical center of the LED is critical rather than the calculated mechanical center based on the component's lead structure. The special camera system measures both physical and optical center and makes the necessary adjustments before placement. It also can acquire the images in either single field of view or multiple field of view modes.[5]
A separate camera on the pick-and-place head photographs fiducial marks on the PCB to measure its position on the conveyor belt accurately. Two fiducial marks, measured in two dimensions each, usually placed diagonally, let the PCB's orientation and thermal expansion be measured and compensated for as well. Some machines are also able to measure the PCB shear by measuring a third fiducial mark on the PCB.
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Variations
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To minimize the distance the pickup gantry must travel, it is common to have multiple nozzles with separate vertical motion on a single gantry. This can pick up multiple parts with one trip to the feeders. Also, advanced software in the newer generation machines allows different robotic heads to work independently of each other to further increase the throughput.
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 that can be incorporated on to the pick and place machine. The glue is added before component placement. It is dispensed by nozzles or by using jet dispensing. Jet dispensing dispenses material by shooting it towards the target, which in this case, is the circuit board.
See also
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References
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What is an SMT Pick and Place Machine?
What is an SMT Pick and Place Machine?
An SMT pick and place machine is a type of automated equipment used in the electronics assembly industry for the assembly of surface mount technology (SMT) components. It is designed to pick up small electrical components&#;such as capacitors, resistors, and integrated circuits&#;from a component reel or tray, place them accurately onto a printed circuit board (PCB) or substrate.
The SMT pick and place machine is a highly precise piece of equipment that can rapidly pick components from reels or trays, inspect them on the fly and place them accurately on the bare PCB. This makes it an efficient tool for businesses that need to manufacture large quantities of electronics components quickly and accurately.
Types of SMT Pick and Place Machines
SMT pick and place machines are available in both batch and in-line automated versions, allowing businesses to choose the one that best meets their needs. The cost of these machines can vary widely depending on size and features, making them accessible to all budgets. In addition, they offer a high degree of accuracy and consistency for surface mount technology components, making them ideal for assembly line production. With the right machine, businesses can produce highly reliable PCB assemblies in house.
Batch pick and place equipment is best for low volume SMT requirements when high speed is not necessary. These types of machines require an operator to load the bare PCB into the machine but the workplace and components are all organized for some level of process control. More common are fully automated in-line pick and place machines where the components required for the particular PCB are loaded on the machine and the component pick up and placement is done automatically by a robotic vacuum head. The machine is programmed to optimize the pick and placement for each PCB, knowing what components are required for that PCB, where the components are located on the placement machine and where the bare PCB is located in the working area.
Why Should I Use Pick and Place?
Pick and place equipment can provide manufacturers with the ability to control manufacturing and deliveries of final product better than when PCB assembly is outsourced. By automating the pick and place process, manufacturers are able to reduce overall labor costs as well as improve productivity. Automated pick and place systems can also help to control inventory and order fulfillment due to its ability to quickly respond to changing demand for final product. Manufacturers that use pick and place automation are often able to reduce their production costs while improving efficiency and accuracy. The reduced overhead and improved productivity lead to increased profits for manufacturers, allowing them to better compete in their respective markets.
In summary, having the ability to build PCB&#;s in house with pick and place equipment provides manufacturers with several significant cost-saving benefits that enable them to remain competitive in their respective industries.
What Are The Main Components of a Pick and Place Machine?
All automated pick and place machines have some basic elements. There is the ability to hold the bare PCB in place so the robotic head can accurately place the components, the machine also needs to hold a wide range of components on tape and reel or in trays. And then there is the pick and place head, some machines have only 1 pick up nozzle and some have 15 or more. The more pick up nozzles the faster the machine can assemble components on the PCB.
Higher speed machines will automatically transport the bare PCB into position in the machine and ready the board for placement by accurately locating the board using a top-down camera for alignment. Typical machines will hold a minimum of 100 individual components feeders and some room for components that come on trays and not on reels. Some machines can hold up to 200+ different component types when they come on reels.
The main factor of all pick and place machines is the head, the head generally has a quantity of individually controlled vacuum pick up nozzles that are mounted on an X-Y gantry. The entire head assembly moves over to the feeder locations to pick up the required components, then once those components are on the head they travel over to the bare board location and they are individually placed onto the correct location of the PCB. This happens very fast with slow machines placing between 1,000 and 5,000 components per hour and fast machines placing upwards of 90,000 components per hour
It is important to remember that each PCB must have its own program or instructions as to which components are to be placed in which locations on the bare PCB. This instruction set will let the operator know what components should be placed in each feeder location on the machine. It will also enable the engineer to know how long it will take to build or assemble the components on each PCB. In this way they can know how many PCB&#;s can be assembled in each shift or day.
Once the in line pick and place machine is set up, it can build PCB&#;s in a &#;hands-free&#; mode with bare PCB&#;s transported into the machine automatically and once all components are placed they fully assembled PCB transports out into the next stage of assembly, this is either automated visual inspection or directly into a reflow oven where all components are soldered into place.
How Do I Select SMT Pick and Place Equipment?
When selecting SMT pick and place equipment, consider the following factors:
Speed: The speed of the machine is an important factor as it will determine how quickly you can assemble PCB&#;s as well as the ability to change from one PCB to another. Make sure you choose a machine that has a high enough cycle rate to meet your production needs.
Flexibility: This is another key factor when selecting a type of pick and place machine. Some machines are &#;built for speed&#; and others are designed for maximum flexibility. You need to understand the requirements of your own companies production requirements. Machines can sometimes be considered designed for High - Mix, Low volume (maximum flexibility) or for high-volume and low mix (generally very high speed and not designed for switching to different products multiple times / day.
Accuracy: Accuracy is a critical factor when selecting SMT pick and place equipment. Almost all pick and place machines are highly accurate but if the build is for semiconductor and die placement a very high degree of accuracy may be required. Most pick and place machines are accurate to 1 or 2 thousands but die placement machines need to be accurate to 10 - 15 microns. Choose a machine that meets your accuracy requirements.
Support: Adding pick and place equipment without having the required level of support could make the investment in equipment ineffective. The best machines in the world are useless if they are idle and not producing PCB&#;s. Companies must make the necessary investment in trained personnel and in proper support from all departments in the company. You will need full support from a variety of departments in your own company including engineering for accurate and updated data about each PCB to be built and the revision level, purchasing so that you have all the components in stock that are required for each build, material handling and management so that the right components are delivered to the machine when it is time to build PCB&#;s and manufacturing so that they are trained on how to use the pick and place machine effectively.
Features: Each SMT pick and place machine offers different features. Some machines offer additional capabilities like solder paste or glue dispensing, electrical testing of chip components on the fly, some offer placement inspection cameras. Consider what features are important for your application and select a machine that offers them.
By considering these factors, you will be able to find an SMT pick and place machine that meets your needs. It is important to understand your companies needs and select equipment that meets the majority of those requirements. With the right equipment in place, you can ensure your production line runs efficiently and effectively.
How Much Does a Pick and Place Machine Cost?
The cost of a SMT pick and place machine can vary significantly depending on its size, features, and capabilities. While cost should not be the only factor in deciding on an SMT pick and place machine, it is an important one to consider. In general pick and place machines start at approx $150,000 and can go up to $400,000. This is without the additional investment in component feeders which can add up to 50% to the cost.
The total cost of ownership (including maintenance and consumables) should also be taken into consideration when selecting a pick and place machine. By choosing the right size, feature set, and capabilities for the specific application, it is possible to get the best value for your money and ensure that you purchase the right pick and place machine for the job.
Conclusion
By investing in automated pick and place equipment, manufacturers are able to reap the benefits of increased efficiency, improved deliveries, reduced inventory and improved quality control. All of these factors lead to improved cost structure and both tangible and intangible benefits of in-house production. The improvements in automation, the lack of qualified manual assemblers for PCB&#;s and the reshoring of PCB assembly from overseas to the US makes this a great time to evaluate bring SMT and PCB assembly back in house.
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