Low pressure molding (LPM) is a process in which a hot-melt polyamide or similar thermoplastic adhesive is injected at relatively low pressure — typically between 1.5 and 40 bar — into a mold cavity that surrounds an electronic component or circuit board assembly. The material flows gently around delicate parts, fills gaps, and solidifies into a seamless protective shell. Because the injection pressure is far lower than conventional injection molding, the process is safe for fragile components such as sensors, microswitches, and fine-pitch connectors.
The technique was originally developed in Europe during the 1980s for automotive connector protection and has since spread across medical, industrial, consumer electronics, and new-energy sectors. Compared with traditional potting, which uses liquid resins that require long curing times, LPM completes in a matter of seconds. The thermoplastic material is also reworkable and recyclable, making it a more sustainable choice.
Key insight: Unlike potting, the entire low pressure molding cycle — material melt, injection, and cooling — can be completed in three fast, repeatable steps. This translates to shorter cycle times, lower energy consumption, and less material waste on the production floor.
LPM is not a one-size-fits-all solution, but it shines in a specific set of scenarios where environmental protection, gentle handling, and speed all matter. Below are the primary application areas where the technology delivers the most value.
Sensors used in medical equipment and industrial automation must endure repeated cleaning, chemical exposure, and temperature swings. Encapsulating these assemblies with thermoplastic material seals them against ingress while preserving signal integrity. low pressure molding for waterproof electronics is particularly valuable here because the low injection pressure will not damage delicate sensing elements or bonded wires.
Inside a vehicle, electronic control units, window-lifter modules, and anti-pinch circuits operate in environments filled with heat, vibration, and humidity. low pressure molding for automotive electronics provides a compact, lightweight, and moisture-proof barrier that helps these modules meet automotive reliability standards. The process is also compatible with overmolding connectors and harnesses, creating an integrated seal that prevents water from creeping along cable pathways.
LED drivers and power-battery management boards benefit from the thermal stability and dielectric protection that LPM materials provide. The encapsulation layer helps dissipate heat away from critical components while insulating them from short-circuit risks.
Any assembly that combines fine wiring with exposed contacts is a candidate for LPM. The process can encapsulate a connector and its attached cable in a single shot, eliminating the need for separate grommets or heat-shrink tubing and streamlining the bill of materials.
Engineers evaluating protection strategies often weigh three options: conformal coating, potting, and low pressure molding. Each has its place, but the trade-offs differ significantly.
| Factor | Conformal Coating | Potting | Low Pressure Molding |
|---|---|---|---|
| Protection level | Thin film; moisture and dust resistant | Full encapsulation; excellent environmental sealing | Full encapsulation; excellent sealing with less stress |
| Processing time | Minutes to hours (drying/curing) | Hours (long cure cycles) | Seconds per cycle |
| Pressure on components | Very low | Low, but shrinkage stress possible | Low and controlled (1.5–40 bar) |
| Reworkability | Limited | Difficult | Reworkable with heat |
| Material recyclability | No | No (thermoset resins) | Yes (thermoplastic) |
In practice, many manufacturers use conformal coating and LPM in combination — coating the full board for baseline protection, then overmolding specific high-risk areas such as connectors or sensors for an added layer of environmental sealing.
Selecting the right manufacturing partner for low pressure molding for pcb assembly goes beyond checking whether a supplier owns the equipment. Several factors determine whether a project will run smoothly from prototype to mass production.
Farway Electronic Co., Limited, based in LongGang, Shenzhen, China, operates a 2,000-square-metre production workshop that covers the full electronics manufacturing chain — from PCB fabrication and component sourcing through SMT, DIP through-hole assembly, conformal coating, low pressure injection moulding, PCBA testing, and finished-product box-build assembly.
On the low pressure molding side, Farway runs four low-pressure injection moulding machines and supports customers from technical consulting and engineering through product and mould development to volume production. The company lists applications including medical and industrial sensors, LED lighting, mobile-phone and power batteries, connector harnesses, circuit boards, and microswitches — aligning with the application areas discussed above.
Quality is backed by four management-system certifications: ISO 9001 (quality), ISO 13485 (medical devices), IATF 16949 (automotive), and ISO 14001 (environmental). Product-level compliance includes UL, RoHS, SGS, and REACH, and the company follows IPC-A-610 as its PCBA assembly standard. Since its establishment in 2018, Farway has served more than 100 industry customers across more than 20 countries and regions.
The advantage of working with a single partner for both PCBA assembly and encapsulation is clear: the same engineering team that places components and runs functional tests also designs the mould and validates the encapsulation, reducing communication gaps and accelerating the path from prototype to production.
If your product needs reliable environmental protection without the long cycle times and shrinkage stress of potting, low pressure molding is worth evaluating early in the design phase. The earlier the encapsulation strategy is considered, the more flexibility there is to optimize board layout, connector placement, and mould geometry together.
A practical first step is to share your BOM, board dimensions, and target environmental requirements with a manufacturing partner that offers both PCBA and LPM services. That partner can then recommend material grades, estimate cycle times, and prototype the mould before committing to production tooling.
Ready to protect your electronics with low pressure molding? Farway Electronic offers integrated PCBA manufacturing and encapsulation services from its Shenzhen facility, with ISO-certified processes and experience across medical, automotive, industrial, and consumer electronics. Contact the team at sales@farway.hk or visit www.farway.hk to discuss your project requirements and request a quotation.
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