The main steps in the LED factory production are: cleaning - loading - welding - packaging - welding - cutting - assembly - testing - packaging. Which is particularly important packaging process, the following process to provide users with a brief look at the current LED technology situation.
First, the chip test
Mirror: whether the surface of the material has mechanical damage and fine potholes.
Second, spread the film
As the LED chip after the scribe is still arranged in close spacing is very small (about 0.1mm), is not conducive to the operation of the process. We use the expansion machine to expand the film of the adhesive chip is the LED chip spacing stretched to about 0.6mm. You can also use manual expansion, but it is likely to cause the chip to fall and waste and other undesirable problems.
Third, dispensing
In the corresponding position of the LED stent silver glue or insulating glue. (For GaAs, SiC conductive substrate, red, yellow, yellow and green chip with back electrode, silver paste is used. For sapphire insulating substrate blue, green LED chip, using insulating glue to fix the chip.) Process difficulty Is the amount of dispensing control, in the colloid height, dispensing position has a detailed process requirements.
Four, prepared rubber
And dispensing on the contrary, the preparation of rubber is the first with a plastic machine on the back of the silver paste on the electrode, and then the back with silver plastic LED installed on the LED bracket. The efficiency of the glue is much higher than that of the dispensing, but not all products are suitable for the preparation process.
Five, hand thorns
Will be expanded after the LED chip (with glue or not prepared) placed in the jaw table on the fixture, LED bracket placed under the fixture, under the microscope with a needle to the LED chip one by one to the appropriate position. There is a benefit compared to manual loading and automatic mounting, making it easy to replace different chips at any time for products that require a variety of chips.
Six, automatic loading
Automatic loading is actually a combination of glue (dispensing) and the installation of the chip two steps, first in the LED bracket on the silver glue (insulation), and then use a vacuum nozzle to suck the LED chip moving position, and then placed in the Corresponding to the stent position. Automatic loading in the process mainly to be familiar with the equipment operation and programming, while the equipment of the glue and installation accuracy to adjust. In the selection of the nozzle as much as possible the choice of bakelite nozzle, because the mouth will scratch the chip surface current diffusion layer.
Seven sintering
The purpose of sintering is to soften the silver paste, sintering requirements to monitor the temperature to prevent the poor batch. Silver sintering temperature is generally controlled at 150 ℃, sintering time of 2 hours. According to the actual situation can be adjusted to 170 ℃, 1 hour. Insulating rubber is generally 150 ℃, 1 hour. Silver plastic sintering oven must be in accordance with the process requirements of 2 hours (or 1 hour) to open the replacement of sintered products, the middle shall not be free to open. Sintering oven can not be used for other purposes to prevent contamination.
Eight, pressure welding
The purpose of welding lead the electrode lead to the LED chip, complete the product inside and outside the lead connection work. LED welding process is gold wire and aluminum wire welding two. Pressure welding is the key link in LED packaging technology, the main need to monitor the process is the pressure welding wire (aluminum wire) arch wire shape, solder joint shape, tension.
Nine, sealant
LED packaging is mainly a little plastic, potting, molding three. Basically, the difficulty of process control is the bubble, more than material, black spots. Design is mainly on the selection of materials, use a combination of good epoxy and stent.
1. Dispensing:
TOP-LED and Side-LED for dispensing. Manual dispensing package on the operating level requirements are high, the main difficulty is the amount of dispensing control, because the use of epoxy in the process will become thicker. White LED dispensing also exists fluorescent powder precipitation caused by the color of the problem.
2. Glue package
Lamp-LED package in the form of potting. Potting process is the first injection molding cavity in the LED injection of liquid epoxy, and then insert the welding of a good LED bracket, into the oven to epoxy curing, the LED from the mold out of the shape.
3. Molded package
Will be welded with a good LED stent into the mold, the upper and lower mold with a hydraulic press mold and vacuum, the solid epoxy into the injection of the entrance of the hydraulic pressure into the mold with the hydraulic plunger into the mold, The glue into the various LED molding groove and curing.
Ten, curing and post-curing
Curing is the encapsulation of epoxy curing, generally epoxy curing conditions at 135 ° C for 1 hour. The molded package is typically at 150 ° C for 4 minutes. After curing is to make the epoxy fully cured, while the thermal aging of the LED. Post-curing is important for improving the bonding strength between epoxy and stent (PCB). The general conditions are 120 ° C for 4 hours.
Eleven, cut and scissors
As the LED is connected together in the production (not a single), Lamp package LED cut with the use of cutting ribs LED brackets. SMD-LED is in a PCB board, the need for dicing machine to complete the separation work.
Twelve test
Test the LED optical parameters, test the size, at the same time according to customer requirements for LED products sorting.
Thirteen, packaging
The finished product is packed in count. Super bright LED need anti-static packaging.