In today’s rapidly evolving electronics industry, protecting sensitive PCB assemblies from environmental stress, moisture, and mechanical damage is more critical than ever. Traditional protection methods such as epoxy potting and conformal coating often come with limitations—rigidity, long curing times, or insufficient coverage.
Low Pressure Injection Molding (LPIM) has emerged as a superior solution for PCB protection, offering a balance of durability, flexibility, and efficiency. This technology is widely adopted in automotive, medical, and industrial electronics where reliability is non-negotiable.
In this guide, we’ll explore how LPIM works in PCB manufacturing, its advantages, costs in 2026, and why companies like KingsunPCB are leading providers of low pressure overmolding solutions.
1. What Is Low Pressure Injection Molding?
Low Pressure Injection Molding is a process that uses heated thermoplastic materials (typically hot-melt polyamides or polyolefins) injected at low pressure (typically 1.5–40 bar) to encapsulate and protect electronic components.
Key Characteristics:
- Low injection pressure prevents damage to delicate PCB components
- Fast cycle times (seconds to minutes)
- Excellent adhesion without primers
- Flexible and shock-resistant encapsulation
Unlike traditional high-pressure molding, LPIM is specifically designed for electronics protection, making it ideal for PCB assemblies.
2. How Low Pressure Injection Molding Works in PCB Manufacturing
2.1 Process Overview
The LPIM process involves:
- Heating thermoplastic material to a molten state
- Injecting it into a mold containing the PCB assembly
- Encapsulating components evenly
- Cooling rapidly to form a protective shell
2.2 Step-by-Step Workflow
- PCB Assembly Preparation – Cleaning and pre-inspection
- Mold Design & Setup – Custom tooling for product geometry
- Material Injection – Low-pressure filling avoids stress
- Cooling & Solidification – Rapid curing (typically <60 seconds)
- Demolding & Inspection – Final quality checks
3. Materials Used in Low Pressure PCB Overmolding
Common Materials
- Polyamide (PA) Hot Melt
- Polyolefin-Based Adhesives
Material Properties
- Strong adhesion to PCB substrates and cables
- High flexibility (ideal for vibration environments)
- Excellent resistance to moisture and chemicals
- Good thermal stability (typically -40°C to 125°C)
Material selection is crucial and depends on the application environment.
4. Advantages of Low Pressure Injection Molding for PCBs
4.1 Superior Protection
- Waterproof and dustproof sealing
- Resistance to chemicals and oils
- Vibration and shock protection
4.2 Component Safety
- Low pressure prevents component displacement
- Ideal for delicate SMT components
4.3 Faster Production
- Short cycle times compared to epoxy potting
- No long curing process required
4.4 Cost Efficiency
- Reduced labor and processing time
- Lower material waste
4.5 Eco-Friendly
- Solvent-free materials
- Reworkable in some cases
5. Applications of Low Pressure Overmolding in PCB Manufacturing
- Automotive electronics (sensors, control modules)
- Consumer electronics (wearables, smart devices)
- Industrial control systems
- Medical devices (portable diagnostic equipment)
- Cable assemblies with integrated PCBs
6. LPIM vs Other PCB Protection Methods
6.1 LPIM vs Epoxy Potting
| Feature | LPIM | Epoxy Potting |
| Flexibility | High | Low |
| Cure Time | Seconds | Hours |
| Reworkability | Possible | Difficult |
6.2 LPIM vs Conformal Coating
- LPIM provides full encapsulation
- Conformal coating offers only surface protection
6.3 LPIM vs High-Pressure Injection
- LPIM = safe for electronics
- High-pressure molding = risk of damage
7. Design Considerations for Low Pressure PCB Overmolding
- Proper spacing between components
- Mold flow channel optimization
- Venting design to avoid air traps
- Thermal management for heat-sensitive parts
- Connector and cable integration
8. Common Challenges and Solutions
Challenges
- Air bubbles or voids
- Incomplete filling
- Adhesion issues
Solutions
- Optimize mold design
- Select correct material viscosity
- Ensure proper preheating and venting
9. Cost Analysis of Low Pressure Injection Molding (2026 Pricing)
Typical Cost Breakdown (2026 USD)
| Cost Item | Price Range |
| Tooling Cost | $500 – $5,000 |
| Material Cost | $0.05 – $0.30 per gram |
| Per Unit Overmolding | $0.50 – $3.00 |
| Prototype Cost | $100 – $500 |
Factors Affecting Cost
- PCB size and complexity
- Material type
- Production volume
- Mold design complexity
Cost Comparison
LPIM is often 20–40% more cost-effective than traditional epoxy potting in medium to high volumes.
10. Why Choose KingsunPCB for Low Pressure Overmolding?
KingsunPCB offers a complete one-stop solution combining:
- PCB fabrication + assembly + overmolding
- Advanced LPIM equipment
- Custom mold design capabilities
- Strict quality control (IPC, ISO standards)
Key Advantages
- Fast turnaround (as quick as 7–10 days)
- Competitive 2026 pricing
- Engineering support for DFM optimization
- Proven experience in automotive and industrial projects
11. Future Trends in PCB Overmolding
- Advanced bio-based hot-melt materials
- Integration with smart sensors and IoT devices
- Miniaturization of overmolded electronics
- Automated inline molding systems
12. Conclusion
Low Pressure Injection Molding is transforming PCB protection by offering a fast, reliable, and cost-effective alternative to traditional methods. Its ability to safeguard delicate electronics while improving production efficiency makes it an essential technology for modern manufacturing.
For businesses seeking high-quality overmolded PCB solutions, partnering with experienced providers like KingsunPCB ensures optimal performance, durability, and cost savings.
13. FAQ About Low Pressure Injection Molding
Q1: What temperature is used in LPIM?
Typically between 180°C and 240°C, depending on the material.
Q2: Is LPIM safe for sensitive components?
Yes, the low pressure ensures no mechanical damage.
Q3: Can overmolded PCBs be repaired?
Some materials allow partial rework, unlike epoxy potting.
Q4: Which industries benefit most?
Automotive, medical, industrial, and consumer electronics.
Q5: Is LPIM cheaper than potting?
Yes, especially in medium-to-large production volumes.