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LED Encapsulation Process Requirements

Edit:Shaoxing Xinshan Science Technology Co.,Ltd   Date:Mar 17, 2017





1. LED chip test

Microscopy: if there is a mechanical damage and pitting surface pockmark (lockhill chip size and the size of the electrode is in line with the process requirement electrode design is complete

2. LED expanding slice

Due to the LED chip after scribing still closer spacing is small (0.1 mm), is not conducive to the process of operation. We adopt expansion machine to bond chip membrane expansion, is LED chip spacing stretching to about 0.6 mm. Also can use manual expansion, but it's easy to cause the chip drop as well as the waste problem.

3. LED dispensing

In LED bracket on the corresponding position of the point of silver glue or insulated. (for GaAs, SiC conductive substrate with electrodes on the back of the red light, yellow light, yellow green chip, using silver glue. For insulating substrate sapphire blue, green LED chip, using insulated to fixed chip.)

Process the difficulty lies in the dispensing quantity control in colloid height, dispensing position has a detailed technical requirements.

Because the silver rubber and insulating rubber in storage and use all have strict requirements, silver glue in the wake of material, mixing, use time are all items must pay attention to in the process.

4. LED for glue

Contrary to some glue, glue is prepared with rubber prepared first silver glue coated electrode on the back of the LED, and then brought back the silver glue LED is installed on the LED bracket. Efficiency is much higher than glue glue, but not all products are suitable for rubber process.

5. LED by hand thorn

After expansion LED chip (glue) has not prepared for glue or placed on the table's fixture, LED stent under fixture, under the microscope LED chips one by one with the needle on the corresponding position. Stab manual and automatic loading frame than have an advantage, convenient to change at different chip, is suitable for the need to install a variety of products of the chip.


6. LED automatic rack

With automatic rack is combined with the adhesive (glue) and install the chip, two steps, first point of silver glue on the LED bracket (insulated), then the LED chip with a vacuum suction nozzle sucking up mobile location, relocation in the corresponding position. Automatic rack main must be familiar with programming and operation on craft and adjust with glue and installation precision of the equipment. Choose in as far as possible on the selection of suction nozzle bakelite suction nozzle, prevent damage on the surface of the LED chip, especially the blue and green chips must be made of bakelite. Because the current diffusion layer on the surface of the steel mouth will scratch chip.

7. The LED sintering

Sintering process is the purpose of the silver adhesive curing, sintering requirements to monitor temperature, to prevent bad batch sex. Silver glue sintered at 150 ℃, the temperature of the general control sintering for 2 hours. According to the actual situation can be adjusted to 170 ℃, 1 hour. Insulated generally 150 ℃, 1 hour.

Silver glue sintering oven must be according to the technological requirements of every 2 hours (or 1 hour) to open the replacement of sintered products, intermediate shall not open. Sintering oven other purposes shall not be made to prevent pollution.


LED bonding 8.

Pressure welding electrodes to the LED chip, the purpose of finished products inside and outside the wire connection.

LED the bonding process with gold ball welding and aluminium wire bonding two kinds. Right is the process of aluminium wire bonding, first on the LED chip electrode pressure on the first point, again pull aluminium wire to the corresponding bracket above, pressure on the break after the second aluminium wire. Golden ball bonding process is burn a ball in pressure before the first point, similar to the rest of the process.

Bonding is the key link in the LED packaging technology, main need to monitor the pressure welding craft gold wire (aluminum) shape of the arch wire, solder joint shape and tension.

LED sealant was 9.

LED encapsulation is mainly a little glue, potting, moulded 3 kinds. Basically process control difficulty is bubble, lack of material, black spots. Design is mainly on the material selection, combined with good epoxy and bracket. (general LED through air tightness test)

9.1 the LED point glue:

LED and Side - the TOP - LED for dispensing encapsulation. Manually dispensing encapsulation of demanding operation level (especially the white LED), the main difficulties is to control the dispensing quantity, because epoxy in use process will thicken. White LED point glue still exist phosphor precipitation lead to a problem of light color.


9.2 the LED glue encapsulation

Lamp - LED packaging in the form of potting. Potting process is first in LED infuse liquid epoxy molding cavity and then inserted into the pressure welding good LED bracket, into the epoxy curing oven, then it will be LED out from the cavity is forming.

9.3 the LED die encapsulation

Pressure welding good LED bracket to be included in the mould, fluctuation two vice mould with hydraulic clamping and pumping air into vacuum state, put solid epoxy glue injection way of entrance heating hydraulic press plunger into the mold in the groove, epoxy along the groove into various LED molding and curing in the slot.

After 10. LED curing and curing

Curing is refers to the encapsulation of epoxy curing, general epoxy curing condition at 135 ℃, 1 hour. Moulded packaging is in commonly 150 ℃, 4 minutes. After cure epoxy is to fully cure, at the same time, thermal aging on the LED. After curing for improving epoxy bonding strength with stents (PCB) is very important. General conditions of 120 ℃, 4 hours.

11. Leds cut reinforced and scribing

Because leds in production are together (not a single), LED Lamp encapsulation using cutting steel cut LED stent reinforcement. SMD - LED is on a PCB, need to complete the separation of scribing machine work.

LED test 12.

Test LED photoelectric parameters, test dimension, at the same time according to customer requirements for separation of LED products.