Spirit & Success, Together, Enbon led display screen
Manuf Process

Manuf Process

Various production processes and technologies are used to produce LED displays. For example, Enbon uses technologies such as LED display chip testing.

Manufacturing Process

As a leading LED display manufacturer in China, Enbon products cover two series of direct plug-in (DIP) and SMD surface mount, which fully meets the requirements of different point spacing, visual distance, brightness and environmental requirements for applications. Established a complete product development, production and quality management system, It has 8 fully-automatic imported SMT production lines, 4 fully-automatic printing machines, and 2 fully automatic drying lines for outdoor products, which can fully meet the needs of different orders and specifications.The products have passed CCC, FCC, CE, IAF, ROHS and other international Standard certification, product and enterprise qualification certification, product test report and patent certificates are complete.

LED Display
Chip Inspection

Whether there is mechanical damage and pitting pits on the surface of the material (lockhill chip size and electrode size is in line with the process requirements electrode pattern is complete).

LED Display Expanding

Because the LED electronic display chip is still arranged closely after the slice is small (about 0.1mm), it is not conducive to the operation of the post-process. We used a reamer to expand the film of the bonded chip, so that the spacing of the LED chip was stretched to about 0.6mm. Manual expansion can also be used, but it is easy to cause chip drop waste and other undesirable problems.

LED Dispensing

Silver glue or insulating glue is placed on the corresponding position of the LED display bracket. (For GaAs, SiC conductive substrate, red light, yellow light, yellow green chip with back electrode, silver glue is used. For blue light and green LED chips with sapphire insulating substrate, insulating glue is used to fix the chips. The difficulty of the process is the control of the amount of glue, in the height of the colloid, the position of the glue is detailed process requirements. As silver glue and insulating glue have strict requirements for storage and use, the awakening, mixing and use time of silver glue are matters that must be paid attention to in the process.

LED Manual Pricking

Place the expanded LED chip (with or without glue) on the fixture of the pricking table, put the LED bracket under the fixture, and prick the LED chip one by one to the corresponding position under the microscope with a needle. Compared with automatic mounting, manual chips have one advantage: it is easy to change different chips at any time. It is suitable for products requiring installation of multiple chips.

LED Screen Automatic Mounting

Automatic mounting is actually a combination of glue (dispensing) and chip installation two steps, the first point on the LED bracket silver glue (insulation glue), and then use the vacuum nozzle to suck up the LED chip moving position, and then placed on the corresponding position of the support. In the process of automatic rack installation, we should be familiar with the operation programming of the equipment, and adjust the glue and installation accuracy of the equipment. In the selection of the nozzle as far as possible to choose bakelite nozzle, to prevent damage to the surface of the LED chip, especially blue, green chip, we must use bakelite. Because the nozzle scratches the current diffusion layer on the surface of the chip.

LED Sintering

The purpose of sintering is to solidify the silver glue, and sintering requires monitoring of temperature to prevent bad batch quality. The sintering temperature of silver glue is generally controlled at 150℃ and the sintering time is 2 hours. According to the actual situation can be adjusted to 170℃, 1 hour. Insulating glue generally 150℃, 1 hour. Silver glue sintering oven must be opened every 2 hours (or 1 hour) according to the process requirements to replace the sintered products, not open at will in the middle. Sintering oven shall not be used for other purposes to prevent pollution.

LED Pressure Welding

The purpose of pressure welding is to lead the electrode to the LED chip and complete the connection of the internal and external leads of the product. LED display pressure welding process has gold wire ball welding and aluminum wire pressure welding two kinds. First, press the first point on the electrode of the LED chip, then pull the aluminum wire to the corresponding bracket, press the second point, and then pull off the aluminum wire. The process of gold wire ball welding is to burn a ball before pressing the first point, and the rest of the process is similar. Pressure welding is a key link to the packaging technology of LED large screens. The main process that needs to be monitored is the pressure welding of gold wire (aluminum wire) arch wire shape, solder joint shape, tension.

LED Sealant

LED electronic display screen packaging uses adhesive, potting, and molding methods. Process control challenges include managing bubbles, material quantity, and black spots. Design focuses on selecting suitable epoxy and support combinations. LED dispensing has TOP-LED and Side-LED options. Manual dispensing requires precise control of epoxy amount. White LED dispensing can have color differences due to phosphor precipitate. LED glue and Lamp-LED encapsulation are common methods. Potting injects liquid epoxy into the molding cavity, curing to mold the LED. LED molding involves filling molds with solid epoxy, which flows into LED grooves and solidifies.

LED Curing And Post-Curing

Curing refers to the curing of encapsulation epoxy. Generally, the epoxy curing condition is 135℃, 1 hour. Molded packaging is generally at 150℃ for 4 minutes. Post-curing is to allow the epoxy to cure sufficiently while thermal aging is performed on the LED. Post-curing is very important to improve the bonding strength of epoxy and PCB. The general condition is 120℃ for 4 hours.

LED Rib Cutting And Slicing

Since the LED display screen is connected together in production (not single), Lamp packaging LED adopts rib cutting to cut off the rib of LED bracket. SMD-LED is on a PCB board,and needs to slice the machine to complete the separation work.

LED Test

Test the photoelectric parameters of LED, check the shape and size, and separate the LED electronic display products according to customer requirements.

Cabinet Forming Process

The box is splice of different modules, the flatness of the box and the gap between modules are directly related to the overall effect of the box assembly. Aluminum plate processing box and die-cast aluminum box are widely used box types at present, and the flatness can reach 10 wires. The stitching gap between modules is evaluated by the distance between the nearest pixels of the two modules. If two pixels are too close, a bright line will light up; if two pixels are too far, a dark line will result. Before assembly, it is necessary to measure and calculate the joint of the mold, and then select the relative thickness of the metal sheet as the fixture to insert in advance for assembly.

Waterproof Process For Outdoor Rental, Solid Installation Products

A LED display waterproof structure production process. Its characteristics are the following steps:

  • Die casting aluminum alloy box;
  • The corrugated waterproof silicone pad is installed in the corrugated groove at the upper part of the aluminum alloy box;
  • The PCB board is installed and fixed on the corrugated waterproof silicone pad inside the aluminum alloy box;
  • The sealant is injected into the gap in the PCB board, the gap between the edge of the PCB board and the edge of the aluminum alloy box, forming a waterproof layer
  • Fix the mask on the PCB board.

LED Display Box Spraying Method

  • The metal material molding box structure;
  • Clean the box structure and remove surface dust;
  • Spray aluminum powder layer on the outer surface of the box;
  • Set a ground solder joint on the aluminum powder layer of the box, and set a protective layer on the ground solder joint;
  • Sand blasting is carried out on the inner surface of the box and the aluminum powder layer;
  • After a period of time, pickling phosphating;
  • Spray the surface of the box after pickling phosphating;
  • The surface of the sprayed box is coated with resin.

Finished Product Inspection Process

  • - After finishing the packaging of finished products in the production department, the packaging team leader shall arrange personnel to send batches to the waiting area for sampling inspection according to different orders, different models and batches. If the order quantity is greater than 500 sets, each 500 sets will be considered as a batch; if the order quantity is less than 500 sets, the whole number will be considered as one batch to submit QA for sampling inspection.
  • Finished product QA shall execute GB/T2828.1-2012 according to working guidelines and related standards Level II once normal sampling inspection, according to AQL serious defect =0, major defect =0.25, minor defect =1.0, test and determine the batch of finished products, and extract 2PCS of finished products for each order for dismantling inspection: the appearance and combination of the operation process, main materials shall meet the requirements, and the sampling inspection results shall be recorded in the finished product inspection report.
  • QA marks the batches of products that have been tested and verified to track and control the quality status of the batches of products;
  • QA shall stamp the "QA PASS" stamp on the side mark of the outer box of the batch product after it is judged to be qualified, and notify the manufacturer to transfer the product to the qualified product area or handle warehousing.
  • QA finds nonconforming products in random inspection, reports to quality assurance supervisor for confirmation, marks and issues the nonconforming batch. Corrective and Preventive Action Report > Or < Quality exception handling sheet > Immediately notify the packaging team leader or production supervisor of production department to sign the machine and move the batch products to the nonconforming area.
  • If appearance/packaging problem is identified after QA sampling, the production department shall analyze the cause and take corrective and preventive measures.
  • If the non-conforming product is a functional problem after QA sampling is confirmed, the quality assurance supervisor/Technical Department technician will analyze the cause of the non-conforming product and fill in the analysis result on < Corrective and Preventive Action Report > Or < Quality exception handling sheet > In the column of cause of problem, if it is caused by human/process/material problem, the technical department shall take corrective and preventive measures
  • When taking corrective measures, relevant departments shall clarify the specific methods of rework and temporary improvement measures, and the quality assurance supervisor shall confirm the rework methods according to the improvement measures.
  • The production department shall rework all the unqualified batches rejected by QA according to the rework instructions, and send them to QA for sampling inspection again after the rework is qualified, and they can be stored and shipped until QA is qualified for sampling inspection.
  • In the process of sampling inspection, if the main defects of a product occur two consecutive times within a month and the problem is the same, the supervisor of quality assurance department shall convene the technical department, Production Department and other relevant personnel to conduct special review and develop improvement countermeasures. QA shall track the processing results and report the tracking results to the general manager.
  • Quality record :QA shall summarize the inspection results of finished products every day, calculate the batch qualified rate and sampling defective rate of the day, and make a weekly report, so as to know the quality status of finished products this week, and track and record the implementation of corrective and preventive measures. QA shall summarize the inspection results of the month and prepare a monthly quality summary report for the purpose of reviewing the achievement of quality objectives and as a basis for quality improvement.