At present, the environmental protection, energy saving and cost-effective features of LED lighting products have been accepted by the market. At the same time, governments in various countries have introduced relevant policies to phase out incandescent lamps and promote the application of LEDs in indoor lighting. The LED light industry will also become an energy and environmental solution. Synonymous with the problem, the LED lighting market is developing rapidly. Such rapid development will inevitably involve the rapid development of LED placement machines and LED production equipment.
SMT and placement machine
Surface Mount Technology (SMT), also known as surface mount technology, surface mount technology, and patch soldering technology. It is a board-level electronic assembly technology that mounts surface mount components (SMD) onto a printed circuit board (PCB). At present, surface mount technology has been widely used in advanced electronic products, especially in computer and communication electronics. Figure 1 shows a printed board made by SMT.
1.1SMT advantages
SMT was born with the development of the electronics industry, and developed with the development of electronic technology, information technology, and computer application technology. The rapid spread of SMT benefits from its advantages.
1) The component assembly density is high, and the electronic product is small in size and light in weight.
2) It is easy to automate and improve production efficiency.
3) High reliability. Automated production technology ensures reliable connection of each solder joint, and its surface mount component (SMD) is highly reliable and shock-resistant because it is leadless or short lead and is firmly mounted on the PCB surface. Strong.
4) Good high frequency characteristics. Surface-mount components (SMD) have no leads or segment leads, which not only reduce the influence of the distribution characteristics, but also adhere to the surface of the PCB, which greatly reduces the parasitic capacitance and parasitic inductance between the leads, so to a large extent Reduced electromagnetic interference and radio frequency interference, improving high frequency characteristics.
5) Reduce costs. SMT increases the PCB layout density, reduces the number of drilled holes, reduces the area, and reduces the number of PCB layers with the same function, which reduces the manufacturing cost of the PCB. The leadless or short lead SMC/SMD saves the lead material, omits the trimming and bending process, and reduces equipment and labor costs. The increase in frequency characteristics reduces the cost of RF commissioning. The volume of electronic products is reduced and the weight is reduced, which reduces the cost of the whole machine. Good welding reliability, resulting in reduced repair costs.
1.2 SMT basic process
(1) SMT is a system engineering technology, and Figure 2 is the basic process flow of SMT.
(2) A typical SMT production line is shown in Figure 3.
It can be roughly seen from Fig. 2 and Fig. 3:
1) There must be three important equipments to form the SMT production line: printing machine, dispensing machine, placement machine, reflow oven, wave soldering machine, and wave soldering process, with the development of surface mount technology, In particular, a large number of applications of the bottom lead integrated circuit package BGA\QFN have become more and more ineffective, so the current mainstream is the process of reflow soldering.
2) Whether it is for mainframe manufacturers or medium-sized machine manufacturers, the classic SMT production line can be generally composed of two placement machines, one high-speed placement machine (chip component placement machine) and one high-precision placement machine ( IC component placement machine), in this way, is conducive to the highest production efficiency of the entire SMT production line. But things are changing now, and many placement machine manufacturers have introduced multi-function placement machines, making it possible to have only one placement machine for the SMT line. A multi-functional placement machine can complete the placement of all components while maintaining a high placement speed, reducing investment, and is favored by small and medium-sized enterprises and academies.
1.3 The simplest placement machine model
As shown in Figure 4, the most basic placement machine consists of a rack, a board clamping mechanism, a feeder (not shown), a patch head, a nozzle, and X, Y, and Z axes, of which Z In addition to being able to move in the Z direction, the shaft can also be rotated in the θ direction (to adjust the angle of rotation of the component from the pad).
1.4 LED Mounter
On the pan-yiyi, the LED placement machine belongs to the surface mount technology (SMT) placement machine. With the development of LED technology, the traditional SMT placement machine can not meet the production needs of the LED industry. At this time, the LED placement machine It came into being.
The LED placement machine is a SMT placement device specially designed for the LED industry to realize the assembly of large-scale LED circuit boards. Equipment requirements are not high, but require fast speed. LED-specific placement machines reduce the cost of placement equipment and increase production efficiency. At present, there are many types of LED placement machines, but their overall layout is similar whether it is a fully automatic high-speed placement machine or a manual low-speed placement machine.
Fully automatic LED placement machine is a high-precision automation equipment controlled by computer and light collector. It consists of rack, PCB transfer mechanism and bearing organization, drive and servo positioning system, placement head, feeder, optical identification. The system, sensor and computer control system are composed of some functions such as suction-displacement-positioning-placement, which completes the fast and accurate placement of SMD on the PCB.
1.5 difference between LED placement machine and traditional placement machine
LED placement machines mainly need to meet the requirements of lamp placement accuracy of 3014, 2835, 3528 and 5050, 5630, 5730. Compared with the processing precision of the traditional placement machine, the LED placement machine requires relatively low. However, the LED placement machine pays more attention to the performance, that is, the stability, speed, operability and size requirements of the machine operation. Therefore, the LED placement machine must have the following design ideas and hard requirements.
1) The intelligent means is more maturely applied to the LED special placement machine. All kinds of sensors with excellent performance can fully collect data for computer disposal during the operation, ensuring the stability and reliability of the entire placement process. At the same time, according to other methods, the LED placement machine should be regularly maintained according to scientific methods and technical specifications. For example, cleaning and washing the surface of the machine and the surface of the circuit board can effectively prevent the internal heat dissipation of the machine due to dust and scale. Causes overheating to burn the device. LED placement machines have good stability to maximize efficiency and reduce production costs.
2) The speed of the LED placement machine must be fast, with a minimum mounting speed of 18000 points/h or more.
3) The easy-to-learn operation method can shorten the training time of personnel extremely, and effectively reduce misoperation, improve production efficiency and product quality in the production process.
4) The LED placement machine must be able to mount a PCB of 1200mm length. Because a large part of the LED replaces the traditional light pipe illumination, the length will greatly exceed the traditional PCB size. In addition to these, in order to ensure that there is no color difference in a single LED panel, the entire batch of LED bulbs to be mounted is required to have the same color temperature BI (BIN generally represents the range of some parameters of the LED bead, and different ranges can be used separately. The number indicates that these parameters include voltage, color temperature, brightness, etc., so there are arguments such as voltage BIN, color temperature BIN, and brightness BIN. BIN can be used to represent the model number of the product.
1.6 Development status of domestic LED placement machine technology
As the huge market potential of the fourth generation of light sources, coupled with the strong support of government policies, the domestic LED lighting industry is almost a leap-forward development. From the popularity of the early LED display to the current transition to LED commercial lighting, indoor lighting, outdoor lighting, lighting engineering, etc., LED products have realized the transition from a single hot product to the application and popularization of LED in all fields.
The development of LED has driven the popularity of related equipment industry. The development trend of reflow soldering, wave soldering, printing machine, LED placement machine and LED packaging equipment is rapid. At present, most of the domestic LED equipment is a small placement machine that can mount a 1.2m light board. Basically, the platform type motion structure is combined with the double swing arm movement mode to realize LED mounting. Track-type LED placement machines are relatively rare in China. This is also the next step in the development of many companies.
At present, the domestic LED placement machine technology is still in a preliminary stage. The products developed can only meet the early needs of some small and medium-sized enterprises. China is a big electronics manufacturing country and needs different grades of domestic LED placement machines. Therefore, it is necessary to optimize the model according to the actual situation, reduce the difficulty of the development of the domestic LED placement machine, and quickly enter the electronic equipment industry.
The most critical technology of LED placement machine
2.1 Precision machine photoelectric integration technology
In the operation of the LED placement machine, this technology is reflected in the fact that the placement head picks up the components from the feeder and passes through the calibration mechanism through precise mechanical movement, and then accurately and quickly mounts the components on the PCB. .
2.2 Visual Technology
Take the non-stop fast shooting positioning technology to achieve optical image capture and positioning.
2.3 Magnetic levitation technology
It can solve the application of high-speed and patch precision motion control technology magnetic suspension linear motor drive, and it has the disadvantages of low speed and high noise of the original servo rotary motor screw. The linear motor uses magnetic levitation technology, which has no friction during movement, no resistance, high speed and long service life.
2.4 efficient intelligent software technology
As the composition and structure of the placement machine become more complex and diversified, the importance of the placement machine software technology is increasingly reflected. Efficient real-time multi-task parallel processing operating system, intelligent placement program optimization, automatic diagnostic technology, etc. will inevitably greatly improve production efficiency and product quality.
2.5 modular and system integration technology
The purpose of modularization and system integration technology is to propose optimized and improved solutions for the three basic requirements of speed, accuracy and flexibility of LED placement machines. Flexible modular technology emphasizes device portability, interoperability, scalability, and configurability, providing device control platform reconfigurability and openness to control requirements, enabling simple and efficient construction and completion of specific requirements Surface mount equipment to increase assembly productivity.
2.6 Motor uses lightweight design concept
The weight of the moving part of the machine can be greatly reduced, so that the power consumed during the operation of the machine is also greatly reduced to only 1/4 of the consumption of the ordinary placement machine, and the power consumption can reach 1/4 or less of the ordinary placement machine; the LED placement machine The placement accuracy is not high, but the speed is required to be faster. At present, there are several professional placement machines for LEDs in China. According to the speed, they can be divided into 4 heads, 6 heads and 8 heads. You can refer to the Temray LED640, LED660V and LED680V LED special placement machines. Actual understanding. The middle number represents the number of placement heads. The higher the number, the higher the speed. The mainstream application of LED placement machine should be able to mount a large area of ​​PCB board, to meet the online requirements, in order to ensure speed.
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