Mixed Technology PCB Assembly

Technology

Benefits

SMT

High component density, compact size, lightweight design, high-speed
placement

THT

Strong mechanical anchoring, excellent for large/high-power components

Technology

Benefits

SMT

High component density, compact size, lightweight design, high-speed placement

THT

Strong mechanical anchoring, excellent for large/high-power components

Advantage

Details

Greater Design Flexibility

Mixed assembly allows high-density SMT components on one or both sides of the PCB while using THT components where mechanical support or high current is required. This enhances layout freedom and improves overall electrical performance.

Superior Mechanical Strength

THT components provide reliable anchoring, making them ideal for: High-vibration environments, Power electronics, Automotive and aerospace systems, Industrial machinery. This ensures long-term durability and mechanical stability.

High Component Density

SMT enables tight placement of miniature components, supporting: Compact device footprints, Lightweight designs, High-speed digital circuits, Multi-functional PCB layouts. Hybrid PCB assembly maximizes density without sacrificing performance.

Cost-Effective & Scalable Production

Sierra Assembly supports: Rapid prototyping, Medium-size production batches, High-volume automated runs. By integrating SMT and THT, mixed technology PCB assembly reduces the need for multiple boards, lowering both development and assembly costs.

Feature

Benefit

Best of Both Methods

SMT offers compactness; THT provides mechanical and thermal stability

High-Power & High-Density Support

Ideal for PCBs requiring dense circuits and robust power features

Reliability Under Extreme Conditions

Performs well under vibration, temperature changes, and heavy electrical loads

Technical Consideration

Risks Prevented

Thermal Profile Co-ordination

SMT and THT components react differently to heat. Careful thermal management prevents: PCB warping, Solder bridging, Joint cracking, Component overheating

Solder Mask Clearence and pad design 

Optimized pad geometries and solder mask openings ensure clean, reliable joints and prevent: Cold joints, Via bridging, Solder wicking

Board Layout Optimization

Proper planning reduces manufacturing risks and ensures smooth integration: Proper spacing between SMT and THT sections, Efficient routing for dense SMT networks, Safe clearance for high-power THT areas

Disadvantage

Explanation

Higher Complexity

Combining SMT and THT increases design and assembly complexity, requiring careful planning.

Longer Production Time

Hybrid boards often take more time to assemble due to multiple processes (SMT + THT + inspection).

Increased Cost

Equipment, labor, and inspection requirements can make mixed assembly more expensive than SMT-only boards.

Thermal Management Challenges

SMT and THT components respond differently to heat, increasing the risk of warping, solder bridging, or joint cracking if not managed properly.

Inspection Difficulty

More complex assemblies may require advanced testing like X-ray inspection and ICT to detect hidden defects.

Limited Automation

Some THT components or dense mixed areas may need manual or selective soldering, limiting full automation.