Instructions for use
LED production process steps are there?
A: 1 Process:
a) Cleaning: ultrasonic cleaning PCB or LED support, and drying .
b) mounting bracket : The LED die ( wafer ) bottom electrode silver paste prepared after the expansion, the die ( wafer ) is placed in the expansion of the crystal thorn bench under a microscope with barbed crystal pen will die mounted on a PCB or LED bracket corresponding pads , followed by sintering silver adhesive curing .
c) pressure welding : aluminum wire or gold wire electrodes connected to the LED die , for current injection leads. LED mounted directly on the PCB , and the general use of aluminum wire welder. ( White TOP-LED production needs gold wire welder )
d) Package : By dispensing with epoxy to protect the LED die and wire up the PCB board dispensing, the shape of the cured gel has strict requirements, which is directly related to the brightness of the backlight of the finished product . This process will also assume point phosphor ( white LED) task.
e) Welding : If the backlight is SMD-LED or other encapsulated LED adoption in the assembly process, the LED needs to be soldered to the PCB board.
f) Cut film : punch die backlight required various diffusion film, reflective film.
g) Assembly : According to the drawings, a variety of handmade materials backlight install the correct position.
h) Test: Check the backlight optical parameters and light uniformity is good.
Package of tasks 1.LED
The outer leads are connected to the electrodes of the LED chip , while protecting the LED chip, and plays the role of improving the light extraction efficiency . Cage with the key process , bonding , encapsulation .
LED package can be said to be varied, the main use of the appropriate dimensions according to different applications , cooling measures and the light effect . LED according to package classification Lamp-LED, TOP-LED, Side-LED, SMD-LED, High- Power-LED and so on .
3.LED encapsulation process
4 . Packaging Process Description
1 chip test : examination : the material surface mechanical damage and pitting Ma Hang (lockhill) chip size and the size of the electrode meets the process requirements electrode pattern is complete.
2 expansion pieces : the LED chip is still arranged in the close spacing of the dicing small ( about 0.1mm), the operation is not conducive to the process . We use the machine to expand chip bonding film expansion, is the spacing of the LED chip stretched to about 0.6mm. Expansion can also be used manually , but it is likely to cause problems and other undesirable waste chips fall .
3 Dispensing : at the point where the corresponding LED holder silver paste or an insulating adhesive ( for GaAs, SiC conductive substrate , red, yellow , green chip with the back electrode , the insulating sapphire with silver plastic liner . end of blue, green LED chips, using glue to fix the chip insulation . )
The difficulty lies in the amount of craft glue control points in colloid height , dispensing position are detailed process requirements.
As the silver plastic and rubber insulation in the storage and use are strict requirements wake silver plastic material , mixing , use of time is important to note the process matters .
4 Preparation of glue : and dispensing Instead, prepare gum is prepared silver plastic coated gum machine on the first LED back electrode , and then put back with silver plastic LED LED mounted on the bracket is much higher than the efficiency of equipment glue point . plastic , but not all products are suitable for preparation of plastic technology .
5 hand stab piece : the LED chip after expansion ( prepared glue or glue equipment ) placed in the thorn -chip platform fixture , LED fixture bracket on the bottom , under a microscope using a needle to stab an LED chip to the appropriate location on manually barbed piece and automatic pallet compared to a benefit of different chips to facilitate change at any time , apply to the need to install multiple chip products.
6 Automatic pallet : automatic loading rack is actually a combination of stick glue ( glue ) and install two steps chips , LED bracket on the first point on the silver plastic ( plastic insulation ) , and then use the vacuum nozzle to suck up the LED chip mobile location , and then placed in position on the corresponding bracket .
Automatic pallet on the main process equipment operators should be familiar with programming , while the glue stick and installation of precision equipment to be adjusted in the selection of the nozzle try to use bakelite nozzle to prevent damage to the surface of the LED chip , especially blue, green the chip must be bakelite . Because steel mouth will scratch the surface of the current diffusion layer of the chip .
7 Sintering : The purpose is to make a sintered silver paste curing , sintering temperature requires monitoring to prevent adverse batch silver paste sintering temperature is generally controlled at 150 ℃, the sintering time is 2 hours may be adjusted according to actual conditions 170 ℃.. , 1 hour . insulation adhesive is generally 150 ℃, 1 hour.
Silver plastic sintering oven process requirements must be separated by two hours ( or one hour ) open replace sintered products, intermediate shall be opened . Sintering oven for other purposes shall not prevent contamination.
8 Bonding : The purpose of bonding the electrode lead to the LED chip , complete the connection work product of the inner and outer lead bonding LED technology has two gold ball bonding and aluminum wire welding pressure . Right is aluminum wire bonding process , the first electrodes on the LED chip first point pressure , and then the aluminum strands to stand above the corresponding pressure points on the second aluminum wire snapped . Gold ball bonding process before the first point in the press before firing a ball , like the rest of the process . Pressure welding LED packaging technology is a key aspect of the process is the need to monitor the main bonding gold ( aluminum wire ) the shape of the arch wire , spot shape , tension. depth study of pressure welding process involves many problems , such as gold ( aluminum ) wire material , ultrasonic power , bonding pressure , chopper ( steel tip ) selection, chopper ( steel tip ) trajectories , etc. ( the figure is under the same conditions , two different pressure out of the chopper pads microscopic photographs, there are differences between the two on the microstructure, thus affecting the quality of products. ) here we no longer tired .
9 dispensing package LED package is mainly a little glue , potting, molding three. Difficulty of process control is basically a bubble , multi- material shortage , black spots . Designed mainly for material selection, combined with a good choice epoxy and bracket suitable dispensing package ( general LED can not pass air tightness test ) as shown on the right of the TOP-LED and Side-LED. Manual dispensing package for demanding operating level (especially white LED), the main difficulty is dispensing volume control because the epoxy will thicken during use . White LED phosphor dispensing there is cause light precipitation color problems.
10 Glue package :. Lamp-LED package in the form of potting potting process is first injected into the mold cavity LED liquid epoxy molding and insert a good bonding LED bracket , let epoxy curing oven . after the LED is disengaged from the mold cavity that is formed .
11 molded package : LED bracket welded to the pressure into the mold , the mold with two pairs of upper and lower hydraulic clamping and vacuum, the solid epoxy glue injection into the inlet channel hydraulic ram pushed heating plastic mold Road , epoxy glue along the road into the groove of each LED molding and cured .
12 curing and post-curing : refers encapsulated curing epoxy curing epoxy curing conditions generally 135 ℃, 1h molded package generally 150 ℃, 4 minutes .
13 after curing: epoxy is cured sufficiently to allow , while the LED thermal aging and curing the epoxy to improve stent (PCB) of the adhesive strength is very important . General conditions of 120 ℃, 4 hours.
14 cut tendons and dicing : Since LED is connected together ( not individual ) in production , Lamp LED package LED bracket using cut tendons cut even tendons. SMD-LED is on a PCB board , you need to complete the separation dicing machine work .
15 Testing : Testing LED photoelectric parameters , test dimensions, while the LED products according to customer requirements for sorting .
16 Packaging : The packaging of finished counting super bright LED antistatic packaging needs .