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Analysis on Structural & Material Waterproof

Dec 22, 2020

Technical Analysis on Structural & Material Waterproofing of outdoor LED Lights

About material waterproofing

Material waterproof design of lamps, the use of filler filling glue to insulate waterproof, the use of sealant bonding between the closed structure between the seams, so that electrical components are completely airtight, to achieve the role of outdoor lamp waterproofing.

1) Fill the glue

With the development of waterproof material technology, various types and brands of lamp-specific potted glue constantly appear, for example, modified epoxy resin, modified polyurethane resin, modified silicone and so on. The chemical formula is different, the elasticity, molecular structure stability, adhesion, anti-uV, heat resistance, low temperature resistance, water repugnance, insulation performance and other physical and chemical performance indicators are different.

Elasticity: the collate is soft, the elastic module is small, then the adaptability is better. Among them, modified silicone elastic module 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, not aging and not cracking. Among them, modified silicone is the most stable.

Adhesion: strong adhesion is not easy to peel, of which modified epoxy resin adhesion is the strongest, but the chemical structure stability is poor, easy to aging cracking.

Water repugnant: indicates the collage's ability to resist water seepage. Among them, modified silicone silicone water repugnant is better.

Insulation: insulation related to product safety indicators, the above several materials of special filling glue are good materials of special potted glue are good.

From the above comprehensive physicolic performance, the performance of modified silicone materials is the best.

2) Seal the adhesive

Sealants are usually tying packaging, suitable for adhesive construction, generally used for wire ends, shell structural parts indirect seam bonding and sealing. Commonly used single-group dispenser, at room temperature and air vapor reaction, natural solidification.

Special attention: some lamp production plants use building neutral curtain wall glue, rather than professional electronic sealant, easy to break down harmful substances, damage lamps.

Certain types of potting gels and sealants in the gel process, will break down a small amount of chemical liquid or gas, such as the lamp beads next to the colloidal decomposition of the lamp beads damage to the lamp beads fluorescent powder, resulting in color temperature drift, or infringe led chip, or decomposition with transparent PC plastic chemical reaction, damage to the PC structure of the substance, and so on. This is a potential hazard in collate applications and must be designed with the colleant manufacturer fully understood of its chemical and physical properties and tested for verification.

Sealant in the lamp shell structure of the bonding seal, the most affected by heat expansion cold shrinkage, especially large lamps, different materials of the line expansion coefficient difference is large, hot expansion cold shrink constantly pulled, very easy to appear cracks. Therefore, the waterproofing ability of the material waterproof design mainly depends on the circuit board filling.

Material waterproof production process is long, 1 irrigation gel solidification cycle needs 24 h, some product design is more complex, even need 2 to 3 irrigation cycle, resulting in a longer shipping cycle, a large number of occupation of production sites, and the production environment is dirty. After colloidal solidification, the product repair is very troublesome.

The structural design of the material waterproof lamp does not need to be too precise, as long as the design reserves the collage potted area, the liquid does not leak, its waterproof performance is very intuitive. Therefore, the material waterproofing process is more suitable for small outdoor lamps, indoor moisture-proof lamps. It is commonly used in low-end and inexpensive public-mode products. Such as soft light belt, small bar lamps, buried lights and other small lamps.

In sum, whether the structure is waterproof or the material is waterproof, for outdoor lamps long-term work stability, low failure rate needs, a single waterproof design is difficult to achieve very high reliability, the potential hidden dangers of water seepage still exist.

Therefore, the design of high-end outdoor LED luminaires, it is recommended to use waterproof technology flexibly, the structural waterproofing and material waterproofing technology to combine the advantages of long-term and short,to ensure the long-term stability of LED circuit work. If the material waterproof design, can be added to the respirator to eliminate negative pressure. And the structure waterproof design, can also consider increasing potted, double waterproof protection, improve the stability of long-term use of outdoor lamps, reduce the rate of moisture failure.

SMD-3