Injection molding is the most efficient method for producing large quantities of plastic parts at high speed and low cost. However, this process is not always compatible for manufacturing parts that encapsulate sensitive electronic components; high melting temperatures and pressures required for standard injection molding can damage these sensitive components. As a result, electronics have traditionally been incorporated into plastic parts with a process called potting.
Potting is a process used to protect electronic assemblies by forming a barrier against moisture, dust, and vibration by casting components in a protective polymer. The process involves placing the electronic assembly into a mold or “pot”, pour-filling the mold with liquid resin (e.g., epoxy, silicone, polyurethane) and allowing the resin to harden. While effective, potting is slow, material-intensive, and often results in heavy products. As more electronics are incorporated into consumer and medical devices, the industry requires a faster, lighter, and more efficient encapsulation method. This can be accomplished using a process called low-pressure injection molding (LPM).
What Is Low-Pressure Injection Molding?
Low-pressure injection molding is similar to traditional injection molding, wherein heated material is injected into a mold cavity using pressure. The differences are that the material is injected at much lower pressures—typically between 1.5 to 40 bar—and the materials used have more moderate melting temperatures (180 to 240°C).
How Low-Pressure Injection Molding Works
- Material Heating: Materials like polyamide, polyolefin, or epoxy resin are heated until they melt. These materials are chosen for their strong adhesion, flexibility, and resistance to environmental conditions.
- Slow Injection: The molten material is injected into the mold at a controlled, slower speed. This slow injection minimizes the risk of damaging fragile parts while still ensuring even distribution and preventing air pockets.
- Mold Filling & Cooling: Once the mold is filled, the material cools down and solidifies. This process creates a uniform bond around the encapsulated components, providing lasting protection.
- Final Product: The end result is a part with precise features, no warping, and minimal defects. The molded part is durable and built to last.
The eco-friendly hot melt adhesives offer excellent waterproofing and protection from harsh chemicals, vibrations, and temperature extremes, making LPM ideal for electronics that need to be ruggedized or waterproofed.
LPM vs. Potting and Traditional Injection Molding
LPM sits somewhere between potting and traditional injection molding in terms of functionality. Here’s how it stacks up against both:
LPM vs. Potting
- Efficiency: Potting involves multiple steps, like mixing, dispensing, and curing, which can take several hours. LPM, on the other hand, completes encapsulation in just three quick steps—taking just a few seconds.
- Cost-Effectiveness: LPM cuts down on material, labor, and shipping costs. In fact, it often costs half the price of a potted part. Additionally, it reduces the need for excessive curing time and space.
- Applications: Potting is useful in some situations, but LPM provides superior adhesion and protection for delicate components like microchips and circuit boards. This means longer product life and greater reliability.
LPM vs. Traditional Injection Molding
- Pressure and Temperature: Traditional injection molding operates under high pressure (100-150 bar) and higher temperatures (280-320°C), which can be too intense for delicate, electronic parts. LPM’s lower pressure and temperature settings make it ideal for fragile components.
- Mold Materials: Traditional injection molding requires durable steel molds, while LPM uses lighter, more affordable aluminum molds. This is a great cost-saver for prototypes or low-volume runs.
- Production Volume: Traditional molding is the best choice for large production volumes, but LPM is perfect for smaller runs, prototypes, or highly specialized parts.
Applications of Low-Pressure Injection Molding
LPM is used to protect delicate parts in many applications, including:
- Electronics: Circuit boards, sensors, and microchips require protection from moisture, dust, and vibration to perform reliably and last longer.
- Medical Devices: Small, sensitive components in medical equipment (like sensors or connectors)
- Automotive: Sensors and electronic components in vehicles that need to stand up to tough conditions, like extreme temperatures and vibrations.
- Consumer Products: Smartphones, wearables, or outdoor electronics that need to be durable and resistant to the elements.
Benefits of Low-Pressure Injection Molding
- Gentle on Components: LPM is designed to protect delicate electronics and other sensitive parts during the molding process, reducing the risk of damage and ensuring consistent performance.
- Improved Waterproofing: The molding process creates high-quality seals that prevent water, dust, and contaminants from getting inside, making it ideal for outdoor or high-moisture applications.
- Reduced Stress: Because LPM uses lower pressure, it minimizes stress on both the part and the mold, which reduces the chances of warping or cracking.
- Cost Efficiency: LPM simplifies the process, reduces waste, and allows for the use of less expensive molds, making it a great choice for low-volume production.
- Eco-Friendly: With its use of sustainable adhesives, LPM reduces environmental impact while still delivering top-notch performance.
- Versatility: LPM can be used in a wide variety of industries, offering customized solutions for different needs.
Considerations and Challenges of LPM
While LPM offers many benefits, it’s not perfect for every situation.
- Material Costs: The adhesives used in LPM can be more expensive than traditional materials. However, the cost savings from faster production and reduced waste often make up for this.
- Not Suitable for Large Parts: LPM is best suited for small to medium-sized components. For large parts, traditional methods may still be the best option.
- Process Sensitivity: Achieving consistent results requires careful temperature and pressure control. Skilled operators and precise equipment are necessary to avoid issues like air pockets or uneven filling.
Why Choose Protoshop for Injection Molding?
Protoshop is recognized for offering exceptional injection molding services that cater to a wide variety of project needs. Whether it’s the traditional high-pressure prototype injection molding or low-pressure molding, our experienced team ensures that the right method is chosen for each unique requirement. Protoshop collaborates with LPM partners to service your overmolding of electronic components with the same quality and speed that we achieve with our prototype molds.
Have questions about low-pressure injection molding or any other molding techniques? Reach out to Protoshop. We’re ready to assist in navigating the process and ensuring the best results for your project.