As more and more lamps use LEDs as light sources, the production process of LEDs has also become very mature. So how are LEDs specifically produced? Below, Baite Lighting takes everyone to understand the production process of LEDs.

1, craft:

A) Cleaning: PCB or LED bracket is cleaned by ultrasonic and dried;

b) Mounting: After the silver electrode on the bottom of the LED die (large wafer) is prepared with silver glue for expansion, the expanded die (large wafer) is placed on the spin table, and the die is placed under a microscope with a spin pen One by one mounted on the corresponding pads of the PCB or LED bracket, followed by sintering to cure the silver glue;

C) Pressure welding: Connect the electrode to the LED die with an aluminum or gold wire welder as a lead for current injection. The LED is directly mounted on the PCB, generally using an aluminum wire welding machine. (To produce white light TOP-LED requires a gold wire welding machine);

D) Packaging: The LED die and the bonding wire are protected by epoxy with epoxy. Dispensing on the PCB board has strict requirements on the shape of the gel after curing, which is directly related to the brightness of the finished backlight. This process will also assume the task of point phosphor (white LED);

E) Soldering: If the backlight source is SMD-LED or other packaged LEDs, the LEDs need to be soldered to the PCB before the assembly process;

F) Film cutting: use a punch to cut various diffusion films, reflective films, etc. required for the backlight;

G) Assembly: According to the requirements of the drawings, manually install the various materials of the backlight in the correct position;

H) Test: check whether the photoelectric parameters of the backlight and the uniformity of light output are good;

2, the task of LED packaging

Is to connect the outer leads to the electrodes of the LED chip, at the same time protect the LED chip, and play a role in improving the efficiency of light extraction. The key processes are mounting, pressure welding, and packaging.

3. LED package

LED packages can be described in a variety of ways, mainly according to different applications using corresponding dimensions, heat dissipation measures and light output effects. LEDs are classified according to the package type Lamp-LED, TOP-LED, Side-LED, SMD-LED, High- Power-LED and so on.

4. LED packaging process

5, package process description

(1) Chip inspection

Microscopy: whether there is mechanical damage on the surface of the material and whether the size of the lockhill chip and the electrode size meet the process requirements, and whether the electrode pattern is complete.

(2) Expansion

(3) Dispensing

(4) prepared plastic

In contrast to dispensing, the preparation is to use a glue preparation machine to apply silver glue on the back electrode of the LED, and then install the LED with silver glue on the back to the LED bracket. The efficiency of preparing glue is much higher than dispensing, but not all All products are suitable for rubber preparation process.

(5) Hand thorn

Place the expanded LED chip (prepared or unprepared) on the fixture of the lancet table, place the LED holder under the fixture, and pierce the LED chip one by one with a needle under the microscope. Compared with automatic mounting, there is an advantage, it is easy to change different chips at any time, and it is suitable for products that need to install multiple chips.

(6) Automatic mounting

Automatic mounting is actually a combination of two steps: dipping (dispensing) and installing the chip. First, apply silver glue (insulating glue) on the LED bracket, and then use a vacuum nozzle to suck the LED chip into the moving position, and then place it in Corresponding bracket position.

(7) Sintering

The silver glue sintering oven must be opened and replaced with sintered products every 2 hours (or 1 hour) according to the process requirements. The middle should not be opened at will. The sintering oven should not be used for other purposes to prevent pollution.

(8) Pressure welding

The purpose of pressure welding is to lead the electrode to the LED chip and complete the connection of the inner and outer leads of the product.

There are two kinds of bonding processes for LED: gold wire ball welding and aluminum wire welding. The picture on the right is the process of aluminum wire pressure welding. First press the first point on the LED chip electrode, then pull the aluminum wire above the corresponding bracket, and press the second point to tear off the aluminum wire. The gold wire ball welding process burns a ball before pressing the first point, and the other processes are similar. Pressure welding is a key link in LED packaging technology. The main thing to monitor in the process is the shape of the gold wire (aluminum wire) arch wire, the shape of the solder joint, and the tensile force.

The in-depth study of the pressure welding process involves many aspects, such as gold (aluminum) wire materials, ultrasonic power, pressure welding pressure, the selection of a split knife (steel mouth), the trajectory of the split knife (steel mouth), and so on. The picture is a microphotograph of the solder joint pressed by two different splitters under the same conditions. The microstructure of the two is different, which affects the product quality.) We will not repeat them here.

(9) Dispensing packaging LED packaging mainly has three types of glue, potting, and molding. Basically, the difficulty of process control is bubbles, lack of material, and black spots. The design is mainly on the selection of materials, and the combination is good. Epoxy and bracket. (General LEDs fail the air-tightness test) TOP-LED and Side-LED as shown in the figure on the right are suitable for dispensing packages. Manual dispensing packaging requires a high level of operation (especially white LEDs). The main difficulty is the control of the amount of dispensing, because the epoxy will thicken during use. There is also phosphor precipitation in white LED dispensing, resulting in light emission. The problem of chromatic aberration.

10 (10) Pouring plastic package

The encapsulation of the Lamp-LED adopts the form of potting. The potting process is to inject liquid epoxy into the LED molding mold cavity, then insert the pressure-welded LED bracket, put it into the oven to allow the epoxy to cure, and then remove the LED from the mold. It is formed when it comes out of the cavity.

11 (11) Molded package

Put the pressure-welded LED bracket into the mold, close the upper and lower pairs of molds with a hydraulic press and evacuate the vacuum. Put the solid epoxy into the inlet of the injection lane and press the hydraulic ejector into the mold lane. The glue lane enters each LED forming groove and solidifies.

(12) Cure and post-cure

Cure refers to the curing of encapsulated epoxy. Generally, epoxy curing conditions are at 135 ° C for 1 hour. Molded package is generally at 150 ° C for 4 minutes.

(13) Post-cure

Cure is to make epoxy fully cured and heat aging LED at the same time. Post-curing is very important to improve the bonding strength between epoxy and bracket (PCB). The general conditions are 120 ° C for 4 hours.

(14) Cutting ribs and scribes

Because LEDs are connected together (not single) in production, Lamp package LEDs use ribs to cut the ribs of the LED bracket. SMD-LED is on a PCB, and a dicing machine is needed to complete the separation.

(15) Test

Test the photoelectric parameters of LEDs, check the dimensions, and sort LED products according to customer requirements.

(16) Packing

Count and package the finished products. Super bright LEDs need anti-static packaging.

The above is a complete set of LED production process. If you want to know more about LED lighting, please visit Baite Lighting official website: http://www.belsz.com/zhaomingzhishi/