Modern electronics are being deployed in environments that would have been considered hostile a decade ago. Automotive control units sit in engine compartments that cycle between sub-zero cold and engine-bay heat. Medical sensors are sterilized, submerged, and expected to function flawlessly for years. Industrial IoT devices monitor equipment in factories where humidity and chemical vapors are constant. In every case, the bare PCBA — no matter how well assembled — needs a protective barrier between its conductive surfaces and the world.
Two technologies dominate this protection space: conformal coating, which applies a thin polymer film across the board surface, and low pressure molding (LPM), which encases sensitive components in a solid thermoplastic shell. Each has its place, and many products benefit from using both in combination. Understanding when to choose LPM — and how to specify it correctly — is what separates a reliable product from a warranty claim.
Low pressure molding is a process in which a thermoplastic hot-melt adhesive is melted at relatively low temperatures and injected at low pressure into a mold cavity surrounding the electronic assembly. The material flows around connectors, sensors, and board-level components, then solidifies into a seamless, water-resistant shell. Unlike traditional potting with two-part epoxies, LPM cures in seconds rather than hours, and it does so without exothermic reactions that can stress heat-sensitive parts.
The result is a mechanical and environmental barrier that seals out water, dust, and corrosive gases while simultaneously strain-relieving solder joints and wire bonds. For applications requiring true waterproof performance — not just moisture resistance — low pressure molding for waterproof electronics has become the preferred encapsulation route across automotive, medical, and industrial sectors.
Both technologies protect circuit boards, but they do so at different levels of intensity. Selecting the right one depends on the severity of the operating environment, the geometry of the assembly, and the cost envelope of the product.
| Factor | Conformal Coating | Low Pressure Molding |
|---|---|---|
| Protection level | Thin film; resists moisture, dust, mild chemicals | Solid encapsulation; resists water immersion, vibration, impact |
| Typical thickness | 25 to 75 microns | 1 mm to several millimeters, fully conformal |
| Processing time | Minutes to hours (drying / curing) | Seconds per shot |
| Reworkability | Removable with solvents or plasma | Difficult to remove once molded |
| Best suited for | Dense boards needing lightweight protection | Connectors, sensors, cable assemblies needing robust sealing |
In practice, many manufacturers coat the full board for baseline protection and then apply LPM selectively to high-risk areas such as battery contacts, sensor housings, or cable exit points. This layered approach maximizes coverage while controlling material cost.
LPM is not a universal solution, but in the right applications it dramatically outperforms alternatives. The following use cases represent the strongest fit for molded encapsulation:
Automotive electronics. Window-lifter controllers, anti-pinch modules, and in-cabin sensors face temperature swings, road vibration, and occasional water ingress. LPM provides a vibration-damping, thermally stable shell that survives under-hood and door-module environments. As a low pressure molding for automotive electronics application, encapsulated cable connectors and sensor housings are common production items.
Medical devices and sensors. Implantable and body-worn devices require biocompatible encapsulation that can withstand sterilization and bodily fluids. Low-pressure processing ensures delicate sensor elements are not damaged during encapsulation, while the solid shell provides a hermetic barrier.
LED lighting. Outdoor and industrial luminaires benefit from LPM around driver circuits and wire entries, blocking moisture that causes corrosion-related premature failure.
Power batteries and connectors. Battery management boards and interconnect harnesses gain both environmental sealing and mechanical strain relief from a single molding step, eliminating the need for separate gaskets and potting compounds.
Choosing a manufacturer for low pressure molding involves more than verifying that they own the equipment. The right partner brings engineering depth, quality system maturity, and integration with upstream and downstream processes.
Process equipment and capacity. A facility should have dedicated LPM machines — not improvised potting stations — and enough units to handle your volume without creating a bottleneck. Farway Electronic, operating from a 2,000-square-metre workshop in Shenzhen, runs four low-pressure injection molding machines alongside its SMT, DIP, coating, and assembly lines, allowing encapsulation to be sequenced naturally after board-level manufacturing rather than outsourced to a third party.
Engineering involvement. Effective LPM starts at the product design stage. Mold design, gate placement, material selection, and wall thickness all influence whether the encapsulation will seal properly and whether the electronics inside will survive the molding cycle. A capable partner offers technical consulting and mold development support, not just a molding service.
Quality system coverage. Encapsulation is only as reliable as the inspection behind it. Look for manufacturers whose quality systems span the full process. Farway's inspection capabilities include AOI, X-ray, thermal imaging, and functional testing, and the company holds ISO 9001, ISO 13485, IATF 16949, and ISO 14001 certifications — covering general electronics, medical devices, automotive, and environmental management respectively. Post-molding verification through pcba testing ensures that the encapsulated assembly still meets electrical specifications before it ships.
Integration with the full manufacturing chain. LPM rarely exists in isolation. It follows SMT assembly, through-hole soldering, and conformal coating, and precedes final box-build assembly. A one-stop partner that controls all of these steps under one roof reduces handoff risk, shortens lead times, and maintains single-source traceability from bare board to shipped product.
The hot-melt adhesives used in LPM — typically polyamide or polyolefin-based compounds — are selected based on the required durometer, operating temperature range, and chemical resistance. Softer durometers absorb vibration better but may be less resistant to abrasion; harder compounds offer better mechanical protection but transmit more stress to internal components. A knowledgeable manufacturer will help you balance these trade-offs against your product's service environment.
Mold design is equally critical. Gates must be positioned so that material flows evenly around the electronics without trapping air or creating voids. Wall thickness should be sufficient to provide robust sealing without excessive material consumption. For complex geometries, prototype tooling allows the design to be validated before committing to production molds — a step that Farway supports through its in-house engineering and tool development capability.
The strongest argument for integrating LPM into a single manufacturing partner is traceability. When the same facility produces the PCB, assembles the PCBA, applies conformal coating, performs low pressure molding, conducts functional testing, and completes box-build assembly, every process step is recorded against the same serial number. If a field failure occurs, the root cause can be traced back through a single quality record rather than across multiple supplier handoffs.
Farway Electronic has built its service model around this integration. Founded in 2018 and based in LongGang, Shenzhen, the company serves more than 100 customers across 20-plus countries in automotive, new energy, security, medical, and communications markets. Its nine core manufacturing services — from PCB fabrication through finished-product assembly — are designed to be selectable individually or combined into a turnkey program. For products that require encapsulated, waterproof electronics, this means a single quote, a single project engineer, and a single quality system covering every step.
Ready to protect your electronics? Whether you need low pressure molding for a new sensor design, conformal coating for a full production run, or an integrated manufacturing partner for your next product, Farway Electronic's engineering team can help you specify the right protection strategy. Contact sales@farway.hk or call 181 2472 7402 to discuss your project requirements.
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