Low Pressure Molding (LPM) is an ideal overmolding electronics method for delicate, low-volume electronic equipment. The LPM process is similar to HPM, but uses less pressure to inject molten plastic into a mold. Because the pressure is reduced, this method requires more time than HPM, but—compared to potting—it offers a variety of benefits to help improve the cost, quality and time involved in overmolding delicate electronics like PCBs, connectors, sensors and cable assemblies.
High Pressure Molding (HPM) is the manufacturing world’s answer to many production woes. Instead of pouring liquid resin, this overmolding method injects the resin at high pressure into a metal mold. The extreme pressure presses the resin more tightly against the mold walls to create greater detail or produce parts with complex geometry. High pressure also makes this process fast, resulting in less production time and resources, a high production rate and, ultimately, a less expensive product.
But, not all products can stand up to the force of high pressure molding. PC board assemblies and other electrical parts are delicate, and require a softer molding approach that can still outperform potting, but doesn’t damage product components.
According to IPC Association Connecting Electronics Industries, the demand for printed circuit boards (PCB) and electronics manufacturing services has increased year-over-year by 39%. This surge is expected to continue. To keep up with demand, manufacturers must develop newer, leaner production processes that result in a faster turnaround time without adding to the cost of ownership or compromising quality.
Traditionally, manufacturers used potting to encapsulate and protect electrical components. This process involves pouring liquid resin over electrical components, boards, or assemblies to insulate and protect the product against thermal shock, moisture, corrosive substances, etc.
The downside of potting is that the process involves many steps and requires a long curing period that increases the cycle time and can be conducive to shrinking, putting the electronic component at risk. Depending on the method used, potting materials and processes can also be quite expensive. For example, vacuum potting or using silicone rubber compounds.
The Benefits of Low Pressure Overmolding Electronics vs. Potting
1. Faster, Simpler Process/Reduced Development Cycle
LPM only involves three steps instead of seven or eight steps involved in traditional potting. The thermoplastic polyamide materials (also referred to as “hot melts”) are heated until they turn into liquid, are injected into a mold (which encapsulates the electronic part) and left to cool and solidify. Unlike potting, LPM doesn’t require a curing process, which also substantially reduces the amount of time and risk involved in encapsulating an electronic part.
2. Less Expensive
By simplifying the process, manufacturers reduce the number of resources and manufacturing time involved in producing the product. This cuts down on the cost of labor and materials, and will ultimately lower the cost of ownership. Thanks to the lower injection pressure involved in LPM, mold sets can also be made using aluminum, which is an affordable material with excellent thermal conductivity.
3. Excellent Resistance and Protection
Despite a reduction in materials, time and cost, low pressure molding still provides delicate electrical parts with excellent protection and temperature or solvent resistance. Low pressure molding creates a watertight encapsulation and considerable room for customization, including the addition of logos and color coding.
4. Environmentally Responsible
The materials used for low pressure molding are non-toxic, non-hazardous and derived from natural ingredients. Additionally, the leftover materials are either biodegradable or can be recycled into new materials. The simplification of the production process also utilizes less energy than the traditional potting process.
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