Introduction to the manufacturing process steps of LED injection molding module

1. LED injection module chip inspection

Microscopic inspection: Whether there is mechanical damage and pitting on the surface of the material, whether the chip size and electrode size meet the process requirements and whether the electrode pattern is complete.

2. LED injection molding module expansion

Because the LED injection molding module chips are still closely arranged with a small spacing (about 0.1mm) after dicing, it is not conducive to the operation of the subsequent process. The film bonding the chips is expanded by a chip expander, so that the spacing between the chips of the LED injection molding module is stretched to about 0.6mm. Manual expansion can also be used, but it is easy to cause undesirable problems such as chip drop and waste.

3. LED injection molding module dispensing

Apply silver glue or insulating glue to the corresponding position of the chip holder. For GaAs and SiC conductive substrates, red light, yellow light, and yellow-green chips with back electrodes use silver glue. For blue and green LED chips with sapphire insulating substrates, insulating glue is used to fix the chips.

The difficulty of the process lies in the control of the amount of glue, and there are detailed process requirements in the height of the glue and the position of the glue. Since silver glue and insulating glue have strict requirements for storage and use, the wake-up, stirring and use time of silver glue are all matters that must be paid attention to in the process.

4. Glue preparation for LED injection module

Contrary to dispensing, glue preparation is to use a glue preparation machine to apply silver glue on the back electrode of the LED injection molding module chip, and then install the LED injection molding module chip with silver glue on the back on the LED injection molding module chip bracket. The efficiency of glue preparation is much higher than that of dispensing, but not all products are suitable for glue preparation.

5. LED injection molding module manual thorn

Place the expanded LED injection molding module chips (with or without glue) on the fixture of the piercing table, place the LED injection molding module bracket under the fixture, and use a needle to pierce the LED injection molding module chips one by one under the microscope. to the corresponding location. Compared with automatic racking, manual thorn chips have an advantage, which is easy to replace different chips at any time, and is suitable for products that need to install multiple chips.

6. Automatic mounting of LED injection modules

The automatic racking actually combines the two steps of dipping (dispensing) and installing the chip. First, put silver glue (insulation glue) on the LED injection molding module bracket, and then use the vacuum nozzle to suck up the LED injection molding module chip. Move the position, and then place it on the corresponding bracket position. In the process of automatic racking, it is mainly necessary to be familiar with the operation and programming of the equipment, and at the same time, adjust the glue and installation accuracy of the equipment. In the selection of nozzles, try to use bakelite nozzles to prevent damage to the surface of the LED injection molding module chips, especially blue and green chips must use bakelite. Because the steel nozzle will scratch the current spreading layer on the surface of the chip.

7. LED injection molding module sintering

The purpose of sintering is to solidify the silver paste, and sintering requires monitoring of temperature to prevent batch failure. The temperature of silver glue sintering is generally controlled at 150 ° C, and the sintering time is 2 hours. According to the actual situation, it can be adjusted to 170℃ for 1 hour. Insulation glue is generally 150 ℃, 1 hour. The silver glue sintering oven must be opened to replace the sintered product every 2 hours (or 1 hour) according to the process requirements, and it must not be opened at will. The sintering oven shall not be used for other purposes to prevent pollution.

8. LED injection molding module pressure welding

The purpose of pressure welding is to lead the electrodes to the LED injection molding module chip to complete the connection of the inner and outer leads of the product. There are two types of pressure welding processes for LED injection molding modules: gold wire ball welding and aluminum wire pressure welding. The process of aluminum wire pressure welding is to press the first point on the LED chip electrode, then pull the aluminum wire to the top of the corresponding bracket, press the second point and then tear the aluminum wire. The gold wire ball bonding process burns a ball before pressing the first point, and the rest of the process is similar. Pressure welding is a key link in LED packaging technology, and the process that needs to be monitored is the shape of the pressure-bonded gold wire (aluminum wire) arch wire, the shape of the solder joint, and the tension.

9. LED injection molding module sealant

The packaging of LED injection molding modules mainly includes three types: dispensing, potting and molding. Basically, the difficulty of process control is air bubbles, lack of material and black spots. The design is mainly about the selection of materials, and the selection of epoxy and brackets with good combination. LED injection molding module dispensing TOP-LED and Side-LED are suitable for dispensing packaging. The manual dispensing package requires a high level of operation (especially white LEDs), and the main difficulty is the control of the amount of glue dispensed, because the epoxy will thicken during use. Dispensing of white LED injection molding modules also has the problem of phosphor precipitation causing color difference in light output. LED injection molding module potting packaging Lamp-LED packaging is in the form of potting. The process of potting is to first inject liquid epoxy into the LED molding cavity, then insert the pressure-welded LED bracket, put it in an oven to cure the epoxy, and then remove the LED from the cavity to form. LED molding package Put the pressure-welded LED bracket into the mold, close the upper and lower molds with a hydraulic press and vacuumize, put the solid epoxy into the entrance of the injection channel, and press the hydraulic ejector into the mold rubber channel for heating. The epoxy enters the molding groove of each LED injection module along the glue channel and cures.

10. LED injection molding module curing and post-curing

Curing refers to the curing of the encapsulated epoxy, and the general epoxy curing conditions are at 135°C for 1 hour. Molded packages are typically held at 150°C for 4 minutes. Post-curing is to allow the epoxy to fully cure, and at the same time to thermally age the LED injection molding module. Post-curing is very important to improve the bond strength of the epoxy to the bracket (PCB). Typical conditions are 120°C for 4 hours.

11. Rib cutting and dicing of LED injection molding module

Since the LED injection molding modules are connected together in production (not single), the Lamp packaged LED injection molding modules use cutting ribs to cut off the connecting ribs of the LED injection molding module brackets. SMD-LED is on a PCB board and requires a dicing machine to complete the separation work.

12. LED injection molding module test

Test the optoelectronic parameters of the LED injection molding module, check the external dimensions, and sort the LED products according to customer requirements.