LED packaging process
4. Packaging Technology Description
a. Chip Test
Microscopic examination: Are there surface mechanical damage and pitting Ma Hang (lockhill)
Chip size and electrode size of the compliance with technical requirements
Electrode pattern is complete
b. expanding film
As the LED chip dicing arranged after the close spacing is still very small (about 0.1mm), is not conducive to post-process operation. We use expansion-chip machine to bond the chip membrane expansion, is the spacing of LED chips stretch to about 0.6mm. Expansion can also be used manually, but it is likely to cause adverse issues such as chips fall to waste.
c. Dispensing
LED stent in place the point corresponding silver plastic or rubber insulation. (For GaAs, SiC conductive substrate, with the back electrode of the red, yellow, yellow, and green chips, using silver glue. Insulating sapphire substrates for blue, green LED chips, using insulating glue to fix the chips.)
Technological difficulty is the control of dispensing quantity in the gel height, dispensing locations are the detailed process requirements.
As the silver glue and insulating rubber in the storage and use are strict requirements, silver glue wake up materials, mixing, use of time are Technology must pay attention to.
d. Preparation of glue
And dispensing the contrary, the prepared gel is prepared by plastic machine should first silver plastic coated electrodes in the LED on the back and then back with a silver glue on the LED installed on the LED bracket. Preparation of rubber is much higher than the efficiency of dispensing, but not all products are applicable to prepare gel process.
e. Hand thorn film
After the expansion of LED chips (prepared or not prepared adhesive glue) placed in the fixture on the barbed-chip platform, LED fixture on the bottom bracket, with a needle under the microscope will be an LED chip, a thorn to the appropriate position. Manual and automatic loading rack barbed piece compared to a good, easy to switch to a different chips at any time apply to the need to install a variety of chip products.
f. Auto-loading rack
Auto-loading rack is in fact a combination of stick glue (Dispensing) and the installation of chip two steps, first LED stand on the point of silver glue (insulating plastic), and then use the vacuum nozzle to suck LED chips from mobile location, and then placed in the the corresponding bracket position.
Automatically installed on the main frame in process equipment operation should be familiar with programming, while the equipment and installation of precision plastic stick to adjust. As far as possible in the choice of nozzle selection of bakelite nozzle to prevent the LED chip surface damage, especially blue, green, chip to be used bakelite for. The fact that steel mouth will scratch the surface of the current diffusion layer chip.
g. Sintering
The purpose is to make sintered silver glue curing, sintering temperature required to monitor, prevent the batch of bad.
Silver plastic sintering temperature is controlled at 150 ℃, sintering time 2 hours. According to the actual situation can be adjusted to 170 ℃, 1 Xiao Shi.
Insulating rubber in general 150 ℃, 1 Xiao Shi.
Silver plastic sintering oven according to process requirements must be separated 2 hours (or 1 hour) to open to replace sintered products, in the middle are not free to open. Sintering oven no further for other purposes, to prevent pollution.
h. bonding
The purpose of bonding the electrode diverted to the LED chip, the finished product to link internal and external leads.
LED's are gold ball bonding process welding and aluminum wire bonding the two. On the right is aluminum wire bonding process, the first electrode on the pressure in the LED chip, the first point, and then to the corresponding bracket aluminum Isla above, the pressure after the second point on the aluminum wire snapped. Gold ball bonding process of the first point in the pressure before firing a ball, the rest of the process is similar.
Bonding is a LED packaging technology, a key link in the main process is the need to monitor bonding gold (Aluminum) arch wire shapes, solder joint shape, Rally.
On the bonding process involves in-depth study of a wide range of issues, such as gold (aluminum) wire materials, ultrasonic power, bonding pressure, chopper (steel mouth) to choose from, chopper (steel mouth) movement trajectories. (The figure is the same condition, two different kinds of chopper pressure pad out of the micro picture, both at the micro-structure there are differences, thus affecting the quality of products.) We are not tired out here.
i. dispensing package
LED package main somewhat adhesive, potting, molding of three. Basically, the difficulty is the bubble process control, multi-Queliao, black spots. Designed mainly for material selection, selection of a good combination of epoxy and stent. (General LED can not airtight test) as shown on the right of the TOP-LED and Side-LED for dispensing package. Manual dispensing package, the operation of a high level of demand (especially white LED), the main difficulty is the dispensing volume control, because the process would be the use of epoxy thickens. Dispensing white LED's are still leading to a light color phosphor deposition problems. Welcome to LED World Net ()
j. filling plastic packaging
Lamp-LED package using potting form. Casting process is first in the LED forming liquid epoxy into the mold cavity, and then insert the LED bracket bonding well placed in oven for epoxy curing, will be LED from the mold cavity or extrusion molding.
k. molded package
Would be a good bonding LED stent placed in molds, the two mold the upper and lower clamping hydraulic machines and vacuum, the solid epoxy adhesive Road, the entrance into the injection heat hydraulic mandrel pressed into molds plastic Road, epoxy-shun Road access to all the plastic molding tank and LED curing.
l. curing and post curing
Curing refers to the package, epoxy curing, general epoxy curing conditions in 135 ℃, 1 Xiaoshi. Molded package, generally 150 ℃, 4 Fenzhong.
m. After the curing
After the cure is to enable the epoxy to fully cure, while LED thermal aging. After curing epoxy for improving stent (PCB) of the bonding strength is very important. The general conditions of 120 ℃, 4 Xiao Shi.
n. cut tendons and dicing
As the LED in production are linked to (not single), Lamp Trim Package LED used to cut off the connection LED bracket bars. SMD-LED is in the midst of PCB board needed to complete the separation of dicing machines work.
o. Test
Test LED electro-optical parameters, test dimensions, but also with customer requirements for LED product sorting.
p. Packaging
Count the finished product packaging. Super bright LED need anti-static packaging.
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