The main processes of LED package manufacturing include die bonding, wire bonding, phosphor coating, lens molding and test sorting. Among them, eutectic soldering, wire bonding, coating and lens forming are the core technologies and equipment in the whole manufacturing process. A brief introduction will be made to the mechanism, technology and equipment of these four major processes and equipment to find out some technical problems that China needs to overcome in the development of LED emerging strategic industries.
At present, in view of the broad industrial application background of LED eutectic technology, developed countries such as Europe and the United States have invested a lot of energy in the research of LED eutectic core technology. As shown in the figure below, the research on eutectic soldering equipment in these countries is mainly concentrated in two directions: one is eutectic hot pressing, and the chip with the eutectic solder layer is bonded to the bracket (substrate) by heating and applying pressure. Together; the second is eutectic reflow, by heating and using a flux to bond the chip with the eutectic solder layer and the support.
The relevant core research and technical achievements abroad mainly focus on CREE , Lumileds, Osram and other foreign LED well-known enterprises. Cree is a leader in the development of high-power LED eutectic soldering equipment, and has launched the EZ9004, a high-power LED series eutectic package. However, due to the complicated process and the need to use the reflow soldering process, there are also shortcomings such as low yield, chip oxidation, floating soldering, and high void ratio, so the device can only be used in research institutions and small batch production. Seoul Semiconductor also introduced high-power products for eutectic soldering.
In recent years, with the rapid development of China's semiconductor industry, related companies and scholars have begun research on LED eutectic soldering processes and equipment. Some enterprises and research institutes are committed to introducing and researching the development trend of eutectic soldering technology, equipment selection, etc. The other part has realized the localization of manual LED eutectic welding machine through imitation and transformation; some companies have developed semi-automated LED eutectic welding machine according to the structure of the placement machine, but the placement machine cannot solve the LED package. In the process, the core problems such as chip oxidation, bonding pressure change, and contact cavity void ratio, so the LED solid crystal equipment modified by the placement machine is still not commercially available. In recent years, with the support of the Guangdong and Guangdong tenders, the cooperation between 45 and Guoxing Optoelectronics has developed prototypes and applications.
The current eutectic welder is still the main technical difficulty in the following aspects:
(1) Design and manufacture of high-precision welding nozzles;
(2) High-speed and high-precision identification and positioning of LED chips and substrates;
(3) High-precision position/force control based on vision in the eutectic process;
(4) Stepped pulse temperature control based on a specific temperature curve during welding.
At present, the main wire bonding machine providers include K&S (also known as KNS), ESEC (European semiconductor equipment), ASM, and Kaijo, which basically monopolize the main gold wire machine market. There are no mature and reliable gold wire machine products in China. Among them, K&S is a US company, ESEC is a Swiss company, ASM is a Hong Kong company in China, and Kaijo is a Japanese company.
The wire bonding technology as the core technology of the wire bonding machine refers to a process technology of connecting the external lead wires of the semiconductor chip with the substrate wiring pads or the pins of the electronic package casing by using the coupling of heat, force and ultrasonic energy, The basic principle is shown below. First, the high-voltage electric spark (EFO) is used to melt the end of the wire passing through the small hole of the file into a spherical shape, and then the lowering of the file, the metal ball is brought into contact with the surface of the die pad under a certain pressure, through the longitudinal direction of the transducer. The combination of ultrasonic vibration, boring pressure and heating energy causes plastic deformation of the contact surface between the metal ball and the pad, the oxide film at the contact interface is destroyed, and uniform atomic bonds are formed by diffusion of the metal atoms on the contact surface and lattice dislocations. After soldering the joint; after the boring tool is lifted a distance with the bonding head, the lead wire is moved to the pad on the lead frame, and finally the wedge soldering (crescent) solder joint is completed under the coupling of ultrasonic energy and heating energy.
Originally used in the form of a series mechanism driven by a rotating electric machine and a ball screw, such as the FB-128 wire bonding machine of Japan Kaijo Co., the bonding speed is only 5 lines/second. By the 1990s, linear motors replaced the wide range of applications of rotary motors with wire bonding equipment, such as the 8028 wire bonder from K&S, USA. The positioning platform utilizes a generalized parallel mechanism supported by linear guides. The movement between the X and Y directions is decoupled by the rolling bearing, and the bonding speed reaches 11 lines/second. By special design for linear motors, Kaijo eliminates the decoupling mechanism and eliminates the decoupling mechanism and applies it to the FB-700 wire bonder with a bonding speed of 16 lines per second. The 3200 wire bonder developed by Swiss ESEC company using this structure has a maximum bonding speed of 21 lines/second and 28 lines/second in the laboratory, which is the highest level in the world.
The main technical difficulties of the current high speed wire bonding machine are:
(1) High-precision position/force control platform technology;
(2) wire bonding technology;
(3) Bonding trajectory planning.
Developed countries such as Europe and the United States have invested a lot of research energy in phosphor technology. The leading companies include Cree, Philips Luminleds, Osram, NORDSON, ASYMTEK, etc. They have mastered phosphor coating technology, conformal coating technology, Keep away from coating technology such as coating, but foreign major companies have been blocking the relevant processes, core technologies and equipment for their own market interests. Domestic manufacturers can only use traditional dispensing technology and technology. Commonly used foreign dispensing machines include equipment produced by Japan Musashi MUSASHI, Iwa IEI, NAKA, Zhongshi Liquid Control NLC, and US NORDSON. The concept of conformal coating proposed by Lumileds has become an important development direction of power white LED packaging technology. At present, internationally advanced white LED manufacturers (Cree, Philips Luminleds, Osram) have begun to sell conformal coating structures, indicating that foreign advanced manufacturers have completed the development of their own conformal coating technology and Some products have been successfully used.
Different LED packaging processes correspond to different phosphor coating equipment. For example, Philips Luminleds originally proposed the 1W power LED packaging process. The current SMD packaging process and COB integrated chip packaging process on the market correspond to the traditional dispensing phosphor coating process, which requires the use of phosphor dispensing equipment. As shown in the figure below, the main methods of dispensing are:
(1) Time/Pressure Type Since the time/pressure type dispensing technology uses only pulsating air pressure and a needle tube to dispense, more than 70% of the dispensing systems use this technology. It works best when the colloidal viscosity is medium and large, and it can point out various shapes such as dots, lines and the like.
(2) The metering type metering dispensing head is a further development of the time/pressure type dispensing technology, which adopts a new design to improve the dispensing performance. Typical of this technology are Archimedes metering tube dispensing and piston dispensing.
(3) The piston type uses a piston-cylinder-like mechanism for dispensing. The gel is first introduced into an open cylinder, and then the motor-driven piston seals the cylinder and creates motion until the fluid in the chamber is completely squeezed from the dispensing head. Since this method actually controls the volume of fluid in the cylinder rather than the fluid pressure, the effect of changes in colloidal properties is avoided. Regardless of how the viscosity of the gel changes, the amount of glue dispensed with this technique can remain constant.
The ceramic substrate LED packaging technology, or wafer-level phosphor coating technology, requires the use of high-precision phosphor atomization spraying equipment. At present, only a few companies such as NORDSON and ASYMTEK in the world can produce it. The schematic diagram of the core atomizer nozzle structure of the core component is shown in the figure below.
The main technical difficulties of current phosphor coating machines are:
(1) Mechanism modeling, control and process of atomized spraying;
(2) Surface uniformity control and thickness control of the phosphor coating;
(3) Modeling of distributed parameter system for phosphor powder spot spraying;
(4) Key visual detection principles and algorithms for uniformity and thickness;
(5) Design and manufacture of high-precision phosphor slurry atomizing nozzle.
As with phosphor coating equipment, different forms of LED packaging require different forms of compression molding equipment. For example, the SMD package structure does not require a die-molding device, and it only needs to be coated with a phosphor and then dried. The ceramic substrate LED packaging process requires the molding of ATOM Corporation of Japan TOWA Corporation and Hong Kong (Netherlands). Equipment; traditional 1W power type LEDs need to be subjected to different processes such as transparent lens, hot pressing and glue injection to complete the stamping and packaging process.
Foreign companies that can produce ceramic substrate LED molding equipment (molding machine) include Japan TOWA Company, Apic Yamada Company, Hong Kong (Netherlands) ASM Company, Holland FICO Company, and Korea HANMI Company. The more advanced die-packing technology is compression molding of TOWA, and the process schematic is shown in the figure below. The commonly used molded packaging equipment in China is mainly equipment of TOWA, ApicYamada, ASM and other companies. Towa's equipment is now the mainstream machine, but the price is very expensive, it is difficult to promote the application in China.
Domestic companies producing stamping and packaging equipment include Taiwan's Tianhe Company, GPM Company, and Single Well Industrial Company. There is basically no company in the mainland that can produce LED die-packaging equipment. The die-pressing package in the molding of the die-molded lens in China is mainly operated manually.
The main technical difficulties at present are:
(1) Development and manufacture of special release materials;
(2) Research and development of high-precision injection molding systems;
(3) Research and development of fully automatic stamping and packaging process and equipment.
Due to the wide application of high-power LEDs in lighting, the performance requirements of high-power LED packaging technology are getting higher and higher. Appropriate phosphor coating and compression molding methods, reasonable lens selection and shape change can effectively improve the light extraction efficiency and service life of white LEDs. New packaging materials, packaging processes, packaging concepts and lens materials and structures are inevitably the main research directions to improve the light-emitting efficiency of white LEDs.
At present, China's LED packaging industry still has the following problems: (1) The localization of key equipment such as phosphor coating machine, die-packing machine, eutectic welding machine, and placement machine is still in its infancy. (2) The key processes and technologies are almost monopolized by several foreign companies, and domestic LED packaging companies need to break through patent blockade. (3) It is urgent to carry out strategic layout from the entire industrial chain of chips, materials, equipment and applications, and concentrate limited resources on technological, material and equipment technology innovation to promote the sound development of China's LED industry.
1, eutectic welding machine
At present, in view of the broad industrial application background of LED eutectic technology, developed countries such as Europe and the United States have invested a lot of energy in the research of LED eutectic core technology. As shown in the figure below, the research on eutectic soldering equipment in these countries is mainly concentrated in two directions: one is eutectic hot pressing, and the chip with the eutectic solder layer is bonded to the bracket (substrate) by heating and applying pressure. Together; the second is eutectic reflow, by heating and using a flux to bond the chip with the eutectic solder layer and the support.
The relevant core research and technical achievements abroad mainly focus on CREE , Lumileds, Osram and other foreign LED well-known enterprises. Cree is a leader in the development of high-power LED eutectic soldering equipment, and has launched the EZ9004, a high-power LED series eutectic package. However, due to the complicated process and the need to use the reflow soldering process, there are also shortcomings such as low yield, chip oxidation, floating soldering, and high void ratio, so the device can only be used in research institutions and small batch production. Seoul Semiconductor also introduced high-power products for eutectic soldering.
In recent years, with the rapid development of China's semiconductor industry, related companies and scholars have begun research on LED eutectic soldering processes and equipment. Some enterprises and research institutes are committed to introducing and researching the development trend of eutectic soldering technology, equipment selection, etc. The other part has realized the localization of manual LED eutectic welding machine through imitation and transformation; some companies have developed semi-automated LED eutectic welding machine according to the structure of the placement machine, but the placement machine cannot solve the LED package. In the process, the core problems such as chip oxidation, bonding pressure change, and contact cavity void ratio, so the LED solid crystal equipment modified by the placement machine is still not commercially available. In recent years, with the support of the Guangdong and Guangdong tenders, the cooperation between 45 and Guoxing Optoelectronics has developed prototypes and applications.
The current eutectic welder is still the main technical difficulty in the following aspects:
(1) Design and manufacture of high-precision welding nozzles;
(2) High-speed and high-precision identification and positioning of LED chips and substrates;
(3) High-precision position/force control based on vision in the eutectic process;
(4) Stepped pulse temperature control based on a specific temperature curve during welding.
2, wire bonding machine
At present, the main wire bonding machine providers include K&S (also known as KNS), ESEC (European semiconductor equipment), ASM, and Kaijo, which basically monopolize the main gold wire machine market. There are no mature and reliable gold wire machine products in China. Among them, K&S is a US company, ESEC is a Swiss company, ASM is a Hong Kong company in China, and Kaijo is a Japanese company.
The wire bonding technology as the core technology of the wire bonding machine refers to a process technology of connecting the external lead wires of the semiconductor chip with the substrate wiring pads or the pins of the electronic package casing by using the coupling of heat, force and ultrasonic energy, The basic principle is shown below. First, the high-voltage electric spark (EFO) is used to melt the end of the wire passing through the small hole of the file into a spherical shape, and then the lowering of the file, the metal ball is brought into contact with the surface of the die pad under a certain pressure, through the longitudinal direction of the transducer. The combination of ultrasonic vibration, boring pressure and heating energy causes plastic deformation of the contact surface between the metal ball and the pad, the oxide film at the contact interface is destroyed, and uniform atomic bonds are formed by diffusion of the metal atoms on the contact surface and lattice dislocations. After soldering the joint; after the boring tool is lifted a distance with the bonding head, the lead wire is moved to the pad on the lead frame, and finally the wedge soldering (crescent) solder joint is completed under the coupling of ultrasonic energy and heating energy.
Originally used in the form of a series mechanism driven by a rotating electric machine and a ball screw, such as the FB-128 wire bonding machine of Japan Kaijo Co., the bonding speed is only 5 lines/second. By the 1990s, linear motors replaced the wide range of applications of rotary motors with wire bonding equipment, such as the 8028 wire bonder from K&S, USA. The positioning platform utilizes a generalized parallel mechanism supported by linear guides. The movement between the X and Y directions is decoupled by the rolling bearing, and the bonding speed reaches 11 lines/second. By special design for linear motors, Kaijo eliminates the decoupling mechanism and eliminates the decoupling mechanism and applies it to the FB-700 wire bonder with a bonding speed of 16 lines per second. The 3200 wire bonder developed by Swiss ESEC company using this structure has a maximum bonding speed of 21 lines/second and 28 lines/second in the laboratory, which is the highest level in the world.
The main technical difficulties of the current high speed wire bonding machine are:
(1) High-precision position/force control platform technology;
(2) wire bonding technology;
(3) Bonding trajectory planning.
3, phosphor coating machine
Developed countries such as Europe and the United States have invested a lot of research energy in phosphor technology. The leading companies include Cree, Philips Luminleds, Osram, NORDSON, ASYMTEK, etc. They have mastered phosphor coating technology, conformal coating technology, Keep away from coating technology such as coating, but foreign major companies have been blocking the relevant processes, core technologies and equipment for their own market interests. Domestic manufacturers can only use traditional dispensing technology and technology. Commonly used foreign dispensing machines include equipment produced by Japan Musashi MUSASHI, Iwa IEI, NAKA, Zhongshi Liquid Control NLC, and US NORDSON. The concept of conformal coating proposed by Lumileds has become an important development direction of power white LED packaging technology. At present, internationally advanced white LED manufacturers (Cree, Philips Luminleds, Osram) have begun to sell conformal coating structures, indicating that foreign advanced manufacturers have completed the development of their own conformal coating technology and Some products have been successfully used.
Different LED packaging processes correspond to different phosphor coating equipment. For example, Philips Luminleds originally proposed the 1W power LED packaging process. The current SMD packaging process and COB integrated chip packaging process on the market correspond to the traditional dispensing phosphor coating process, which requires the use of phosphor dispensing equipment. As shown in the figure below, the main methods of dispensing are:
(1) Time/Pressure Type Since the time/pressure type dispensing technology uses only pulsating air pressure and a needle tube to dispense, more than 70% of the dispensing systems use this technology. It works best when the colloidal viscosity is medium and large, and it can point out various shapes such as dots, lines and the like.
(2) The metering type metering dispensing head is a further development of the time/pressure type dispensing technology, which adopts a new design to improve the dispensing performance. Typical of this technology are Archimedes metering tube dispensing and piston dispensing.
(3) The piston type uses a piston-cylinder-like mechanism for dispensing. The gel is first introduced into an open cylinder, and then the motor-driven piston seals the cylinder and creates motion until the fluid in the chamber is completely squeezed from the dispensing head. Since this method actually controls the volume of fluid in the cylinder rather than the fluid pressure, the effect of changes in colloidal properties is avoided. Regardless of how the viscosity of the gel changes, the amount of glue dispensed with this technique can remain constant.
The ceramic substrate LED packaging technology, or wafer-level phosphor coating technology, requires the use of high-precision phosphor atomization spraying equipment. At present, only a few companies such as NORDSON and ASYMTEK in the world can produce it. The schematic diagram of the core atomizer nozzle structure of the core component is shown in the figure below.
The main technical difficulties of current phosphor coating machines are:
(1) Mechanism modeling, control and process of atomized spraying;
(2) Surface uniformity control and thickness control of the phosphor coating;
(3) Modeling of distributed parameter system for phosphor powder spot spraying;
(4) Key visual detection principles and algorithms for uniformity and thickness;
(5) Design and manufacture of high-precision phosphor slurry atomizing nozzle.
4, compression molding machine
As with phosphor coating equipment, different forms of LED packaging require different forms of compression molding equipment. For example, the SMD package structure does not require a die-molding device, and it only needs to be coated with a phosphor and then dried. The ceramic substrate LED packaging process requires the molding of ATOM Corporation of Japan TOWA Corporation and Hong Kong (Netherlands). Equipment; traditional 1W power type LEDs need to be subjected to different processes such as transparent lens, hot pressing and glue injection to complete the stamping and packaging process.
Foreign companies that can produce ceramic substrate LED molding equipment (molding machine) include Japan TOWA Company, Apic Yamada Company, Hong Kong (Netherlands) ASM Company, Holland FICO Company, and Korea HANMI Company. The more advanced die-packing technology is compression molding of TOWA, and the process schematic is shown in the figure below. The commonly used molded packaging equipment in China is mainly equipment of TOWA, ApicYamada, ASM and other companies. Towa's equipment is now the mainstream machine, but the price is very expensive, it is difficult to promote the application in China.
Domestic companies producing stamping and packaging equipment include Taiwan's Tianhe Company, GPM Company, and Single Well Industrial Company. There is basically no company in the mainland that can produce LED die-packaging equipment. The die-pressing package in the molding of the die-molded lens in China is mainly operated manually.
The main technical difficulties at present are:
(1) Development and manufacture of special release materials;
(2) Research and development of high-precision injection molding systems;
(3) Research and development of fully automatic stamping and packaging process and equipment.
5 Conclusion
Due to the wide application of high-power LEDs in lighting, the performance requirements of high-power LED packaging technology are getting higher and higher. Appropriate phosphor coating and compression molding methods, reasonable lens selection and shape change can effectively improve the light extraction efficiency and service life of white LEDs. New packaging materials, packaging processes, packaging concepts and lens materials and structures are inevitably the main research directions to improve the light-emitting efficiency of white LEDs.
At present, China's LED packaging industry still has the following problems: (1) The localization of key equipment such as phosphor coating machine, die-packing machine, eutectic welding machine, and placement machine is still in its infancy. (2) The key processes and technologies are almost monopolized by several foreign companies, and domestic LED packaging companies need to break through patent blockade. (3) It is urgent to carry out strategic layout from the entire industrial chain of chips, materials, equipment and applications, and concentrate limited resources on technological, material and equipment technology innovation to promote the sound development of China's LED industry.
Turbines consist of runners, turbine boxes, nozzle assemblies, inlet pipes, deflectors and more. The runner is assembled by torque transmission by the shaft and pawn of the generator.
The centerline of the jet is in the same plane as the runner because the uses the dynamic force of the high pressure water stream to rotate the runner and forces the rotor to work while it is rotating.
Turbines have the advantages of dense construction, stable running and easy operation. Small turbines that are usually organized with horizontal shafts and 1-2 nozzles Normal size and larger turbines are most often organized by vertical shafts and 4 or 6 to get more force Equipped on the nozzle.
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Shenyang Zhicheng Heavy Machinery Manufacturing Co., Ltd. , https://www.zhichengmachinery.com