Low pressure injection molding (LPM) is an encapsulation process in which a hot-melt polyamide or polyolefin material is injected at low pressure — typically between 1.5 and 40 bar — into a mold cavity that contains a finished circuit board assembly. The material flows around sensitive components, fills gaps, and solidifies within seconds, forming a seamless, conformal protective shell that adheres directly to the board and its connectors.
Unlike traditional potting, which requires mixing, vacuum degassing, and long cure cycles, LPM is a single-material, single-step process. The lower injection pressure means fragile components — BGA packages, thin ceramic sensors, glass diodes, wire bonds — are not stressed during encapsulation. This is why the technology has spread from its automotive origins into medical devices, industrial sensors, consumer wearables, and communication modules.
Conventional injection molding can run at hundreds of bar. At those pressures, a populated PCBA would be crushed or its solder joints displaced. LPM keeps the molding pressure low enough to surround populated boards without distortion, while still delivering the dense, void-free encapsulation that liquid potting struggles to achieve consistently.
The mistake many product teams make is treating encapsulation as an isolated step sourced from a specialty vendor, disconnected from the rest of the build. In practice, low pressure injection molding delivers the most value when it is embedded inside an integrated PCBA manufacturer China workflow — where the same engineering team that lays out the board, runs the SMT line, and conducts functional testing also controls the encapsulation process.
A connected workflow looks like this: PCB fabrication and component sourcing proceed under the same quality system; SMT and DIP assembly place and solder the parts; conformal coating or low pressure injection molding PCBA protects the assembled board; then ICT, FCT, and visual inspection verify the finished module before box-build assembly. When all of these steps sit under one roof, the encapsulation mold can be designed against the real board stack-up, the coating and molding steps can be sequenced correctly, and defects can be traced back through a single quality record rather than bouncing between suppliers.
Marketing copy for encapsulation tends to repeat the same words — "protection," "reliability," "durability." Those things are true, but the benefits that convince a procurement manager are more concrete. When LPM is integrated into a complete manufacturing flow, the savings and gains fall into several measurable categories.
Potting still has a place for deep-fill enclosures and extreme chemical exposure, but for most board-level protection decisions, the trade-off looks like this:
| Dimension | Low Pressure Injection Molding | Conventional Potting |
|---|---|---|
| Cycle time per part | Seconds (typically 10–60s) | Hours (often 8–24h cure) |
| Injection pressure | Low (1.5–40 bar) | Gravity or vacuum fill |
| Material mixing | Single-component, no mixing | Two-part, metered mix required |
| Component stress | Low — safe for fragile parts | Low pressure, but shrinkage stress possible |
| Rework / failure analysis | Hot-melt removable | Often destructive and difficult |
| Part consolidation | Replaces housings, gaskets, fasteners | Usually requires a potting cup or shell |
LPM is not a universal answer, but it is the right answer across a remarkably broad set of industries. Farway's own service-area catalog reflects exactly where the demand is concentrated.
Window-lifter controllers, playback modules, and sensor packs need vibration resistance and thermal cycling survival — the original use case for LPM.
Sensors and handheld modules benefit from biocompatible encapsulation that supports sterilization and protects fine-pitch components.
Battery management boards and power conversion modules require insulation, thermal stability, and resistance to conductive dust.
Outdoor modules face humidity, UV, and temperature swings. A conformal molded shell outperforms coating-only protection in harsh enclosures.
For a medical PCBA manufacturer working to ISO 13485, the single-step, void-free nature of LPM is especially valuable because it produces a consistent, inspectable encapsulation layer that survives documentation and process validation. For automotive work under IATF 16949, the cycle-time and part-consolidation gains support the cost targets that Tier 1 programs demand.
Encapsulation is only as reliable as the system around it. Before selecting a partner for low pressure injection molding, product teams should expect clear answers to a few practical questions.
LPM is not free. The initial mold and process development carry a setup cost, and the hot-melt materials are priced above generic epoxy potting compounds. But the total cost of ownership usually favors LPM once cycle time, part consolidation, scrapped rework, and floor-space utilization are counted. A molded module that replaces a housing, gasket, and potting cup — and cures in under a minute — typically beats a potted assembly on per-unit cost once volumes rise above the prototype stage. For programs that also need prototype through volume production under one partner, the economics improve further because the same mold design and process recipe scale without re-qualification.
Low pressure injection molding is a powerful technology, but it delivers its full value only when it is treated as one stage in a controlled, traceable manufacturing chain — not as an outsourced afterthought. When the same engineering team that designs the board, runs SMT and DIP, applies conformal coating, and performs functional testing also controls the LPM step, the result is a module that is designed, built, protected, and verified under a single quality system.
That integration is exactly the model a Shenzhen-based electronics manufacturing services China partner is built to provide. With a 2,000-square-metre production workshop, SMT and DIP lines, conformal coating and low-pressure injection molding capacity, in-line ICT/FCT/X-ray testing, and certifications spanning ISO 9001, ISO 13485, IATF 16949, and ISO 14001, the same factory that builds the board can encapsulate it, test it, and ship the finished module — with one quality record from bare PCB to boxed product.
If your product needs reliable, low-stress encapsulation backed by a full PCBA, testing, and box-build workflow, talk to an integrated manufacturing partner rather than a standalone encapsulation shop. Reach out to discuss your board, your environment, and your volume — and get a single quote that covers the whole chain from bare board to finished product.
Hey there! Your message matters! It'll go straight into our CRM system. Expect a one-on-one reply from our CS within 7×24 hours. We value your feedback. Fill in the box and share your thoughts!