LED outdoor lamps and lanterns, 7 big waterproof basic common sense!
Outdoor lighting lamps and lanterns need to withstand the test of ice and snow, wind, rain and lightning for a long time, and the cost is high, and because it is difficult to use on the outer wall, it must meet the requirements of long-term stable work. The LED is a delicate semiconductor component, if damp, there will be chip moisture absorption phenomenon, damage to the LED, PcB and other components, therefore, the LED is suitable for work in dry and low temperature. To ensure the long-term and stable operation of LED under harsh outdoor conditions, the design of waterproof structure of lamps and lanterns is extremely critical.
At present, the waterproof technology of lamps is mainly divided into two directions: structural waterproof and material waterproof. The so-called structural waterproof, is in the product of the various structural components after the combination, has a waterproof function. And the material waterproof, is the product design, set aside potting glue closed electrical components of the position, assembly with glue material to achieve waterproof. Two kinds of waterproof design are suitable for different product routes, each has its own advantages factors affecting the waterproof performance of lamps ultraviolet rays have a destructive effect on the wire insulation layer, shell protective coating, plastic parts, potting glue, sealing rubber ring rubber strip and adhesive exposed outside the lamp. After the wire insulation layer is aged and cracked, the water vapor will penetrate into the lamp through the gap of the wire core. After the lamp shell coating aging, the shell edge coating cracks or peeling, there will be a gap. After the plastic shell is aged, it will deform and crack. The aging of electronic potting glue will produce cracking. Sealing rubber ring aging deformation, there will be a gap. The adhesive between the structural components ages, and gaps can also occur when the adhesion is reduced. These are UV damage to the waterproof ability of lamps. outdoor temperature changes a lot every day. In summer, the surface temperature of the lamp can rise to 50~60 ℃ during the day, and drop to 10~20 qC at night. In winter, the temperature can drop to below zero in ice and snow days, and the temperature difference varies greatly throughout the year. Outdoor lamps in the summer high temperature environment, the material accelerated aging deformation. When the temperature drops below zero, the plastic parts become brittle and crack under the ice and snow.
with the development of waterproof material technology, various types and brands of lamps and lanterns special potting glue appear continuously, for example, modified epoxy resin, modified polyurethane resin, modified organic silica gel and so on. Different chemical formulations, potting flexibility, molecular structure stability, adhesion, resistance to uV, heat resistance, low temperature resistance, hydrophobicity, insulation properties and other physical and chemical performance indicators vary.
Elasticity: the colloid is soft, the elastic modulus is small, the adaptability is better. The elastic modulus of modified organic silicone is the smallest.
Molecular structure stability: Under the long-term action of uV, air and high and low temperature, the chemical structure of the material is stable, and it does not age and crack. Among them, modified organic silica gel is the most stable.
Adhesion: strong adhesion is not easy to peel off, of which modified epoxy resin has the strongest adhesion, but the chemical structure is less stable and easy to age and crack.
Hydrophobicity: Indicates the ability of a colloid to resist water penetration. The modified organic silica gel has better hydrophobicity.
Insulation: insulation is related to product safety indicators, the above several materials of special filling glue are good material of special potting glue are good.
From the above physical and chemical properties, the modified silicone material is the best.
sealant is usually tubular packaging, suitable for glue construction, generally used for wire ends, shell structural parts of the joint bonding and sealing. Commonly used single component formula, at room temperature and air water vapor reaction, natural solidification.
Special attention: some lamp manufacturers use neutral curtain wall glue for construction, rather than professional electronic sealant, which is easy to decompose harmful substances and damage lamps.
Some types of potting and sealant in the solidification process, will decompose a small amount of chemical liquid or gas, such as the lamp bead next to the colloidal decomposition of the lamp bead phosphor powder damage, resulting in color temperature drift, or against the LED chip, or decomposed with transparent PC plastic chemical reaction, damage the PC structure of the material, and so on. This is a potential hazard in colloid applications, and the design must be fully understood from the colloid manufacturer for its chemical and physical properties, and tested and verified.
In the bonding and sealing of the lamp shell structure, the thermal expansion and contraction are the most affected, especially for large lamps, the linear expansion coefficients of different materials are quite different, and the thermal expansion and contraction are constantly pulled, which is prone to cracks. Therefore, the waterproof ability of the material waterproof design mainly depends on the circuit board potting.
The production process of material waterproofing is long, one glue filling and solidification cycle takes 24 h, and some product designs are more complicated, even requiring 2 to 3 glue filling cycles, resulting in a long delivery cycle, a large number of production sites, and a dirty production environment. It is very troublesome to repair the product after the colloid solidifies.
The structural design of the material waterproof lamp does not need to be too precise, as long as the design reserves the colloid potting area, the liquid does not leak, and its waterproof performance is very intuitive. Therefore, the material waterproof process is more suitable for small outdoor lamps, indoor moisture-proof lamps. Usually in the low-end and cheap male mold products in a large number of applications. Such as soft lights, small strip lights, underground lights and other small lamps.