Low pressure injection molding is an innovative manufacturing process between injection molding and potting. It is injection molding at very low pressures and very low temperature with hot melt adhesives. It is a cost effective alternative to epoxy potting for protection of fragile electronic components. It offers superior strain relief compared to conventional plastic injection molding. Typically benefit of Superior material properties of water-tight encapsulation with excellent Physical Properties & Chemical Properties.
Due to the requirements of various application environment, such as high and low temperature, dust, waterproof, ultraviolet, chemical medium resistance, etc., the structure of different products involved in different industries can not meet all the requirements, so they can only enhance the performance of their own products with the help of different processes, so as to adapt to different application environment. Therefore, different protection technologies are required, and low pressure injection molding is one of them.
At present, the most commonly used protection technologies are: potting(which is divided into a variety of adhesive systems, including epoxy, silica gel, UV glue, etc.), coating, heat shrinkable sleeve, thermosetting materials, 3D molding, plasma powder coating, ceramic packaging, high-pressure injection molding, etc.
The advantages are mainly reflected in the efficient and can be molded into structural parts. Compared with the traditional protection process, such as potting, coating, heat shrinkable sleeve, high pressure injection molding, etc., it is not only faster, but also can compensate for the defects of these processes, such as stress, high temperature, high pressure, complicated production steps, etc.
The traditional potting process is mainly complex. A product needs to achieve the purpose of protection. First of all, it needs to have a potting shell. When the potting glue enters the shell, it needs to be vacuumed to solve the problem of bubbles. Moreover, most potting adhesives have a long time to fix. Normally, it takes several hours or even 1 day to complete the curing, even use heating process, it also takes a few minutes, and the appearance is not guaranteed to be consistent. The low pressure injection molding process is mainly reflected in the simple operation process, only need to implant products in the mold, through a few seconds that can get the same appearance of products, greatly improving the production efficiency and product unity.
Coating protection is commonly used on PCB. The main feature is that the thickness of coating is relatively thin, most of them are used in relatively narrow space such as mobile phones and flat plates, as well as simple dust-proof requirements for large circuit boards. The thickness of spraying is generally different from micron level to millimeter level. To obtain higher protection level, repeated spraying is required to obtain. Because of its strong volatility, it needs a closed space during spraying, and the curing method is also long. Generally, it needs heating and curing for about half an hour. After each spraying, it can be sprayed again. The water-proof protection of low pressure injection molding is better than coating The waterproof grade of coating is IP55, IP56, IP66, etc., while the low pressure injection molding can reach to IP68.
The heat shrinkable sleeve is generally used in the field of wiring harness. Its main features are fast, easy to operate and low cost. However, for the harness with waterproof requirements, the stability is too poor. When the heat shrinkable sleeve is cured by hand-held hot air gun on the harness, it is difficult to cover the whole area. Therefore, the problem of high defect rate or poor stability will be caused. What low pressure injection molding can bring is the consistent waterproof stability, and the appearance can obtain a unified appearance due to the material characters, while the heat shrinkable sleeve is uncontrollable according to the random change of thermal shrinkage.
First of all, high pressure injection molding products are irreplaceable in most fields. Only in some overmolding protection aspects, because of the high pressure and temperature, the products can be damaged in the protection process or can not achieve the expected protection purpose. Low pressure injection molding and high pressure injection molding are complementary relations, and low pressure injection molding can be used to protect in advance, then us high pressure injection molding to protect parts.