Packaging technology plays a critical role in protecting electronic components and products in the manufacturing industry. "Low-pressure molding" is an innovative packaging method gaining widespread attention and usage, particularly as a viable replacement for traditional potting techniques. This article delves into the concept, advantages, and application areas of low-pressure molding.

What is Low-Pressure Molding?

　　Low-pressure molding（LPM）, also known as "low-pressure over-molding" or "low-pressure injection molding," is, as the name suggests, a low-pressure encapsulation and protective manufacturing process primarily employed for sensitive electronic components, such as circuit boards. This innovative technique utilizes low-pressure injection of hot melt adhesive, which is a thermoplastic material. The hot melt adhesive operates at lower temperatures and pressures compared to traditional molding processes, making it an excellent packaging solution for fragile and sensitive electronic components. This gentle encapsulation process ensures the protection of delicate parts while also offering benefits such as reduced cycle times and increased production efficiency in the manufacturing of electronic devices.

Advantages of Low-Pressure Molding

Time Saved + Labor Reduced + Material Saved = Cost Reduction

• Time Saved: Compared to traditional potting, heating, and curing times are significantly reduced, leading to shorter production cycles. Additionally, the use of multi-cavity molds can enhance output rates.

• Labor Reduced: The low-pressure molding process is straightforward, requiring only the placement of components into molds and the activation of the injection button. This reduces the technical skill required of operators, significantly lowering the risk of operational errors and ensuring high yields and stability.

• Material Saved: As depicted in Figure 1, low-pressure injection allows for freedom in shaping without the constraints of enclosure space, enabling the material to be applied where needed, resulting in a substantial reduction in material usage.

Low-Pressure Molding Process

    Low-pressure molding involves using molds to secure and encapsulate electronic components. Both the low-pressure injection mold and the low-pressure injection equipment are crucial components of the Low-pressure molding process, determining production efficiency and yield.

Low-pressure molding can be succinctly divided into 3 steps:

1. Placing electronic components into the mold.

2. Injecting low-pressure material to completely encase the electronic components.

3. Opening the mold indicates that the material has cooled and can be removed.

    Effective mold design can minimize defects such as bubbles, voids, shrinkage, or flash.

Low-Pressure Molding Materials

    Low-pressure injection material takes the form of hot melt adhesive. Low-pressure hot melt adhesive materials are typically made from Polyamide resin, a polymer synthesized through polymerization reactions. This resin comes in various types, mixed with other additives, processed, and modified to meet specific performance requirements. The manufacturing process includes resin melting, mixing, and pelletization, among other steps. These materials are easily moldable during low-pressure injection and solidify during cooling. Different formulations result in variations in melting point, adhesion, hardness, temperature resistance, and viscosity.

How to Choose Low-Pressure Injection Materials?

• Environmental Requirements: Consider factors like temperature, humidity, exposure to chemical environments, UV exposure, and more.

• Mechanical Strength Requirements: Evaluate hardness, flexibility, stress tolerance, flexibility, and impact resistance, among other factors.

• Sealing Requirements: Determine the required waterproofing level or airtightness, such as IPX8 or positive pressure 50kPa.

    The selection of the most suitable material depends on a comprehensive assessment of specific application requirements and the pros and cons of the materials involved.