In the encapsulation process of photovoltaic modules, solar panels below 2W are usually encapsulated by the glue-dropping process. The encapsulant is made of epoxy resin crystal glue, which is composed of high-purity epoxy resin, curing agent and other components. The cured product has the characteristics of water resistance, chemical corrosion resistance, colorless and transparent, dustproof, and not easy to deteriorate and turn yellow. The use of the crystal glue can not only protect the surface of the craft product, but also increase the surface gloss and brightness, and further increase the surface decoration effect. The glue drop process can also be used for surface decoration and protection of handicrafts made of metal, ceramics, glass, plexiglass and other materials.
First stick a double-sided tape on the bottom plate to stick and fix the crystal silicon wafer. The bottom plate is better made of nylon. In order to save costs, many manufacturers use plastic cardboard as the bottom plate. In the natural environment, the bottom plate will expand and shrink due to changes in temperature and humidity, resulting in the breakage of the finished silicon wafer.
Pass the solder strips at both ends of the soldered solar cell strip through the two holes on the bottom plate and stick it with the double-sided adhesive on the bottom plate (the front side of the bottom plate); the tin strips at both ends of the crystalline silicon pass through the two holes on the bottom plate (the bottom plate The back side); the tin strips at both ends of the crystalline silicon are soldered to the positive and negative points of the bottom plate with an electric soldering iron.
Arrange the tested crystalline silicon solar panels on a special rack, and drip glue (epoxy resin) onto the panels. Generally, the glue dripped cannot completely cover the solar panel, and it needs to be adjusted by hand.
The function of vacuuming is to make the glue and the bottom plate completely fit to prevent the generation of air bubbles.
What the baking does is make the glue melt and stick to the base plate.
1. Glue-dropping process utensil preparation
Weighing equipment: electronic balance.
Dispensing equipment: wide-mouth flat-bottomed cup, round glass rod.
Work carrier: square glass plate, carrier spacer.
Drying equipment: oven.
2. The operation steps of the glue-dropping process
(1) Prepare the necessary utensils and equipment such as weighing instruments, glue dispensing equipment, work carriers, drying equipment, and the work to be dispensed in place.
(2) Place the electronic balance, oven, work carrier and work surface and adjust the level.
(3) Use a dry and clean wide-mouth flat-bottom container (tool) to weigh the A glue, and at the same time weigh the B glue in proportion (usually 3:1 weight ratio).
(4) Stir the AB mixture left and right or clockwise and clockwise with a round glass rod, and at the same time, the container (tool) should preferably be tilted 45 degrees and keep rotating, and continue to stir for 1~2min.
(5) Put the stirred AB mixed glue into a soft plastic bottle with a pointed mouth for dispensing.
(6) When the glue dripping area is slightly larger or the number of glue dripping is large, in order to accelerate the elimination of air bubbles in the glue, a fire gun with liquefied gas as fuel can be used to defoam after the fire. When defoaming, the flame of the musket should be adjusted to a state of complete combustion, and the flame should preferably be kept at a distance of about 25cm from the surface of the work object. The walking speed of the musket should not be too fast or too slow, just maintain an appropriate speed.
(7) After the bubbles are completely eliminated, the work can be moved horizontally into the oven for heating and curing. The temperature adjustment should be baked at about 40 °C for 30 minutes and then raised to 60 °C-70 °C until the glue is completely cured.
(8) If there are strict requirements on the effect of glue dripping, it is recommended to let the work that has dripped glue be dried at a natural level.
3. Precautions for glue-dropping process
(1) Appliances such as electronic balances, ovens, work surfaces or work carriers must be placed horizontally, otherwise it will affect the accuracy of weighing or cause glue spills on the work that has just been dripped with glue.
(2) When weighing glue with an electronic balance, the weight of the container must be removed to avoid inaccurate weighing.
(3) The containers used must be dry, clean and dust-free, otherwise it will affect the surface effect of the glue after curing, resulting in undesirable phenomena such as ripples, water marks and pitting.
(4) The glue must be accurately weighed according to the weight ratio. The imbalance of the ratio will make the glue dry for a long time or the hard glue will become soft.
(5) Be sure to stir the glue evenly, otherwise the surface of the glue will appear tortoise shell pattern or resin pattern after curing, or the glue will be incompletely cured.
(6) The operation site and working environment must be ventilated, and must be free of dust and debris, otherwise it will affect the transparency of the colloid or make the surface of the glue solidified with spot effect.
(7) The relative humidity of the air in the working environment is recommended to be controlled within 68%, and the on-site temperature is preferably 23℃~25℃. If the working environment is too humid, the surface of the glue will be oxidized into fog or bubbles that are difficult to eliminate. Too low or too high temperature will affect the curing and use time of the glue.
(8) The work that has dripped glue should be dried in the concentrated area, and the drying temperature should be controlled at 28℃-40℃.
(9) If you need to speed up the speed, you can use the method of heating and curing, but it must be dried in the concentrated drying area for more than 90 minutes before heating. The heating temperature should be controlled within 65 °C, and the specific drying time should be based on the glue itself. to decide.
E-07AB and E-08AB type glues can be fully cured within 8h at 65℃. Routine operation adopts room temperature curing at 28℃-35℃, and the time should be about 20h, which can ensure the quality of the glue to the greatest extent.
(10) After the glue bucket is opened, it should be covered immediately after pouring out the glue, so as to prevent the glue from being oxidized and crystallized due to prolonged contact with the air.
4. Glue-dropping process equipment
In addition to manual dispensing, the dispensing process can also be performed using a fully automatic dispenser device. Automatic dispensing machine devices are widely used in semiconductor, electronic components, LCD manufacturing and other fields. Its principle is to press the glue into the feed pipe connected to the piston through compressed air. When the piston rushes upward, the piston chamber is filled with glue, and when the piston pushes down, the glue is pressed out from the dispensing head. The automatic dispensing machine is suitable for fluid dispensing, and the degree of automation is much higher than that of the manual dispensing machine. Judging from the effect of dispensing, the quality level of its products will be higher.
The automatic dispensing machine device has the function of three-dimensional space, not only can take any chart on the plane, but also take the three-dimensional picture of space (multiple planes); it has a USB interface, and the program can be transferred between the machines; it has a vacuum return The suction function ensures no glue leakage and no wire drawing. It can be used with a dispensing valve and a large-capacity pressure barrel (when the amount of glue to be pointed is large).