LQFP Package Explained: Pin Pitch, Dimensions & Applications
13 min
The LQFP package (Low-Profile Quad Flat Package) is a widely used surface-mount IC package known for its fine pitch, compact size, and reliable performance in modern electronics. Commonly found in microcontrollers, embedded systems, and industrial devices, LQFP packages offer a balance between high pin density and easy inspection.
In this guide, we’ll explain what an LQFP package is, how it works, its dimensions, applications, and PCB design considerations—helping engineers and manufacturers choose the right packaging solution for their projects.
What Is an LQFP Package?
An LQFP package, short for Low-Profile Quad Flat Package, is a type of surface-mount integrated circuit (IC) package featuring gull-wing leads on all four sides and a reduced body height. It is designed to provide high pin density while maintaining a relatively thin profile, making it suitable for compact and high-performance electronic systems.
Compared with standard QFP package, LQFP offers a lower package thickness, which helps meet modern product requirements for slim and lightweight designs. The leads extend outward and downward from the package body, allowing reliable solder joints and easy visual inspection after assembly.
LQFP packages are commonly used in microcontrollers, digital signal processors, communication chips, and automotive control units, where stable electrical performance and manufacturing reliability are critical.
Leadframe and Gull-Wing Lead Design
LQFP packages use a metal leadframe, typically made from copper alloy, as the internal structural and electrical backbone. The silicon die is attached to the leadframe and connected to the leads through fine gold or copper bonding wires.
The external leads adopt a gull-wing shape, bending outward and then downward to form solderable terminals. This design provides several advantages:
● Strong mechanical bonding to PCB pads
● Good solder fillet formation
● Easy optical inspection
● Improved reworkability
Because each lead is exposed and accessible, LQFP packages are easier to inspect and repair than leadless packages such as QFN or BGA.
Body Height and Low-Profile Features
One of the defining characteristics of LQFP is its reduced body thickness. Typical LQFP package heights range from 1.0 mm to 1.4 mm, depending on the pin count and manufacturer.
The low-profile structure helps:
● Reduce overall device thickness
● Improve thermal path consistency
● Support compact enclosure designs
● Meet portable and embedded system requirements
This thin profile makes LQFP especially popular in consumer electronics, automotive modules, and industrial controllers where space constraints are critical.
LQFP Package Dimensions, Pin Pitch, and Size Standards
LQFP package dimensions and pin pitch play a critical role in PCB layout design, manufacturing yield, and long-term reliability. Because LQFP is a fine-pitch surface-mount package, precise dimensional control is essential for achieving stable solder joints and minimizing assembly defects.
Most LQFP packages follow standardized mechanical outlines defined by JEDEC and IPC specifications. However, slight variations may exist between manufacturers, so designers should always verify package drawings in the official datasheet before finalizing their layouts.
Understanding these dimensional parameters helps engineers select the correct footprint, optimize routing, and reduce the risk of bridging or open solder joints.
Common Pin Counts in LQFP Packages
LQFP packages are available in a wide range of pin counts to support different levels of functional integration. The most commonly used configurations include:
● 32 pins
● 48 pins
● 64 pins
● 100 pins
● 144 pins
● 176 pins
● 208 pins
Lower pin-count LQFP packages are typically used in simple controllers and interface chips, while high pin-count versions are common in advanced microcontrollers, DSPs, and communication processors.
As pin count increases, lead pitch becomes smaller, requiring higher PCB fabrication accuracy and tighter assembly process control.
Standard Pin Pitch Sizes
Pin pitch refers to the center-to-center distance between adjacent leads. In LQFP packages, fine pitch is one of the defining features.
Typical LQFP pin pitch options include:
● 0.8 mm (coarse pitch, easier assembly)
● 0.65 mm (standard industrial pitch)
● 0.5 mm (fine pitch, high-density designs)
● 0.4 mm (ultra-fine pitch, advanced applications)
Smaller pitch enables higher I/O density but also increases the risk of solder bridging and misalignment. For pitches below 0.5 mm, advanced stencil design, precise placement, and controlled reflow profiles are strongly recommended.
How to Read LQFP Package Drawings
LQFP package drawings provide essential mechanical information for PCB footprint design and manufacturing verification. These drawings are usually included in semiconductor datasheets and follow standardized drafting conventions.
Key parameters in LQFP drawings include:
● Body length and width (D × E)
● Lead length and width (L, b)
● Lead pitch (e)
● Overall package height (A)
● Seating plane reference
Designers should pay special attention to tolerance ranges, as variations can affect solder joint quality. It is best practice to design PCB footprints using the maximum and minimum limits specified in the drawing rather than nominal values alone.
Using IPC-recommended land pattern guidelines in combination with manufacturer drawings ensures optimal solderability and long-term reliability.
LQFP vs Standard QFP
LQFP (Low-Profile Quad Flat Package) and standard QFP (Quad Flat Package) share the same basic gull-wing lead design. The key differences are summarized in the table below:
| Feature | Standard QFP | LQFP |
|---|---|---|
| Body Height | 2.0–3.6 mm | 1.0–1.4 mm (low-profile) |
| Pin Pitch | 0.8–0.65 mm | 0.65–0.4 mm (supports finer pitch) |
| Applications | Older electronics, larger boards | Slim devices, multilayer PCBs, portable electronics |
| Soldering & Assembly | Slightly more forgiving for thicker boards | Better coplanarity; lower risk of open joints in reflow |
| Mechanical Stability | Thicker body; more robust physically | Balanced between thinness and strength |
Key Takeaways:
● LQFP is preferred for compact, low-profile designs.
● Both support similar pin counts, but LQFP handles finer pitch more reliably.
● LQFP improves assembly consistency in modern SMT production.
LQFP vs TQFP
TQFP (Thin Quad Flat Package) is another thin QFP variant. The differences are subtle but important for engineers:
| Feature | TQFP | LQFP |
|---|---|---|
| Body Height | ~1.0 mm | 1.2–1.4 mm |
| Lead Thickness | Thinner leads | Slightly thicker, better thermal robustness |
| Mechanical Stability | More fragile for manual handling | More forgiving, easier assembly |
| Applications | High-volume consumer electronics | Industrial, automotive, embedded control |
| Soldering | Requires precise reflow | Slightly more tolerant to thermal variations |
Key Takeaways:
● TQFP is extremely thin, ideal for mass-produced compact devices.
● LQFP balances thinness and reliability, making it suitable for industrial and embedded applications.
● Lead size and body stability make LQFP easier to inspect and repair.
Advantages and Disadvantages of LQFP Packages
LQFP (Low-Profile Quad Flat Package) offers a balanced solution between high pin density and manufacturability. Understanding its advantages and limitations helps engineers choose the right package for their designs.
| Aspect | Advantages | Disadvantages |
|---|---|---|
| Profile & Size | Low-profile design (1.0–1.4 mm) saves vertical space, ideal for compact devices | Slightly thicker than ultra-thin packages like TQFP or QFN |
| Assembly & Inspection | Gull-wing leads allow easier soldering, optical inspection, and rework | Fine-pitch variants (<0.5 mm) require precise stencil and placement |
| Mechanical Strength | Leads are robust enough for manual handling | Not as mechanically compact as leadless packages like QFN/BGA |
| Electrical Performance | Supports moderate high-speed signals and reliable connectivity | Limited I/O density compared to BGA or QFN |
| Thermal Performance | Good thermal dissipation through leads and body | Large ground pads may require special reflow attention |
| Cost & Availability | Widely available; mature manufacturing processes reduce cost | Slightly larger PCB footprint than chip-scale packages |
Key Advantages of LQFP Packages
● Compact and Low-Profile: Saves board height without compromising reliability.
● Ease of Soldering and Inspection: Gull-wing leads simplify assembly and visual checks.
● Mechanical Reliability: Strong enough for handling and automated pick-and-place.
● Standardization: Supported by JEDEC and IPC, ensuring footprint compatibility across manufacturers.
Disadvantages of LQFP Packages
● Not Ultra-High Density: Cannot match BGA or QFN in pin count vs area ratio.
● Fine-Pitch Challenges: Pitch below 0.5 mm requires precise stencil, reflow, and inspection.
● Moderate Thermal Performance: May require heat sinks or careful thermal design for high-power ICs.
Summary:
LQFP is a versatile package bridging ease of assembly and compact design. It’s ideal for industrial, automotive, and embedded electronics but may not be optimal for ultra-high-density, thin mobile devices or very high-speed ICs.
Typical Applications of LQFP Packages
LQFP packages are widely used in electronics because they balance pin density, reliability, and assembly ease. Their low-profile design and gull-wing leads make them suitable for a variety of industries, from consumer devices to industrial electronics.
1. Microcontrollers and DSPs
● LQFP packages are the go-to choice for MCUs (Microcontrollers) and DSPs (Digital Signal Processors).
● Common in embedded systems, IoT devices, and control boards.
● Supports moderate pin counts and fine-pitch requirements for signal processing applications.
2. Automotive and Industrial Electronics
● Widely used in engine control units (ECUs), sensors, and industrial controllers.
● LQFP’s robust leads and standardized dimensions ensure reliable solder joints in high-vibration environments.
● Low-profile design allows integration into space-constrained automotive modules.
3. Consumer Electronics
● Found in devices such as smart TVs, set-top boxes, gaming consoles, and home automation controllers.
● Supports moderate-speed signals and compact PCB layouts.
● Allows easy visual inspection and repair during assembly.
4. Communication Devices
● Used in network processors, Wi-Fi/Bluetooth modules, and RF ICs.
● Supports high pin counts while maintaining manufacturability.
● Compatible with standard SMT assembly and reflow processes.
5. Prototyping and Development Boards
● Popular in evaluation boards, Arduino shields, and breakout modules.
● Easy to hand-solder or assemble with stencils in small-scale production.
● Offers a balance between professional-grade assembly and DIY-friendly handling.
Key Takeaways:
● LQFP packages are versatile: suitable for industrial, automotive, consumer, and communication electronics.
● Their low-profile, gull-wing lead design enables reliable assembly, easy inspection, and repair.
● High-density applications with extreme size constraints may require alternatives like QFN or BGA, but LQFP remains a strong choice for most mid-density designs.
PCB Layout and Footprint Guidelines for LQFP Packages
Correct PCB layout is crucial for LQFP packages. Proper land patterns, pad spacing, and solder mask design ensure reliable solder joints, minimal bridging, and long-term device performance. Following JEDEC and IPC standards reduces manufacturing issues and improves first-pass yield.
Recommended Land Pattern Design
| Parameter | Recommendation | Notes |
|---|---|---|
| Pad Shape | Rectangular or slightly rounded | Matches gull-wing leads; improves solder fillet formation |
| Pad Size | Slightly smaller than lead width | Prevents solder bridging |
| Pad Spacing | Follow pitch minus 0.05–0.1 mm | Adjust for solder paste volume and fine-pitch leads |
| Solder Mask | Mask-defined pads for fine-pitch (<0.5 mm) | Reduces risk of shorts and solder balls |
| Via Placement | Avoid placing vias directly under leads | Can cause solder wicking and tombstoning |
Pro Tip: For pitches below 0.5 mm, always use mask-defined pads and check with 3D solder paste simulation tools.
Pad Spacing and Solder Considerations
● Lead Pitch Awareness: 0.4–0.5 mm pitch requires high-precision stencil printing.
● Solder Paste Volume: Too much paste → bridging; too little → weak joints.
● Stencil Thickness: 0.12–0.15 mm is common for fine-pitch LQFP.
● Solder Mask Expansion: 5–10 µm around pad edges helps reduce shorts while maintaining solder wetting.
Routing Strategies for Fine-Pitch LQFP
1. Trace Width: Minimum 0.15–0.2 mm for signals; adjust for current.
2. Via Positioning: Place vias away from pads; consider via-in-pad only with filling.
3. Thermal Relief: Ground and power pads may need thermal relief to prevent soldering issues.
4. Layer Planning: High-pin-count LQFP may require multi-layer routing to manage fan-out.
5. Clearance: Maintain minimum 0.2 mm spacing between traces for 0.5 mm pitch packages.
Following these guidelines ensures consistent solder joints, avoids tombstoning, and improves AOI/X-ray inspection results.
Quick Checklist for LQFP PCB Design
● Verify footprint against manufacturer datasheet
● Use mask-defined pads for fine-pitch leads
● Optimize solder paste stencil thickness
● Maintain proper trace width and spacing
● Avoid vias under pads unless filled/plated
● Include thermal relief for large pads
Key Takeaways:
A well-designed PCB layout for LQFP packages prevents common SMT defects such as bridging, tombstoning, and cold joints, and ensures reliable assembly in high-volume manufacturing.
For high-pin-count LQFP assembly, ensure your PCB fabrication and SMT process meet fine-pitch requirements.
Assembly and Soldering Guide for LQFP Packages
Proper assembly and soldering of LQFP packages are essential to ensure reliable electrical connections and minimize defects like bridging, tombstoning, and cold joints. Depending on the production scale and pin pitch, different soldering methods can be used.
1. Reflow Soldering (Preferred for Production)
Reflow soldering is the standard method for LQFP packages in SMT assembly:
Steps:
1. Paste Application: Apply solder paste using a stencil with proper thickness for fine-pitch leads.
2. Component Placement: Position the LQFP on the PCB using a pick-and-place machine or carefully by hand for prototypes.
3. Preheating: Slowly heat the board to ~150°C to allow solvents in the solder paste to evaporate.
4. Reflow: Heat to peak temperature (~235–245°C for SAC305 lead-free solder) to melt the paste and form fillets.
5. Cooling: Allow natural cooling to solidify joints; avoid forced air cooling which may shift components.
Tips for Success:
● Ensure proper stencil thickness for uniform paste deposition.
● Avoid excessive solder paste; fine-pitch leads require precision to prevent bridging.
● Inspect post-reflow with AOI or visual inspection.
2. Hand Soldering (Repair or Prototyping)
Hand soldering is only recommended for low-volume repairs or prototypes, especially for LQFPs with pitch ≥0.5 mm:
Steps:
1. Apply a minimal amount of solder paste or flux to each pad.
2. Preheat the pad slightly to reduce thermal shock.
3. Use a fine-tip soldering iron (preferably 25–30 W for lead-free solder).
4. Gently touch the lead and pad to melt solder; avoid dragging the tip across leads to prevent bridging.
5. Inspect under a magnifying lens for uniform fillets.
Tips:
● Use flux pens or no-clean flux to reduce oxidation and improve wetting.
● For fine-pitch LQFP (<0.5 mm), hand soldering is not recommended; reflow is safer.
3. Common Assembly Defects and How to Fix Them
| Defect | Likely Cause | Quick Fix |
|---|---|---|
| Bridging | Excess paste or misalignment | Use solder wick or reflow with careful heat control |
| Tombstoning | Uneven heating or pad size mismatch | Preheat board evenly; check footprint design |
| Cold Joint | Insufficient heat or old paste | Reflow with fresh flux; ensure proper peak temperature |
| Solder Balls | Solvent rapid evaporation or stencil misalignment | Adjust stencil thickness; slow preheat phase |
4. Inspection and Quality Control
● AOI (Automated Optical Inspection): Detects shorts, opens, and misaligned components.
● X-Ray Inspection: For hidden leads, especially under high-pin-count LQFP.
● Manual Inspection: For small batches or prototypes, ensure shiny, concave solder fillets.
Following proper assembly, soldering, and inspection protocols ensures high reliability, particularly in industrial, automotive, and embedded applications.
Key Takeaways:
● Reflow soldering is the most reliable method for LQFP packages.
● Hand soldering is only suitable for prototypes or repairs.
● Proper paste volume, temperature control, and inspection prevent common SMT defects.
Conclusion
LQFP (Low-Profile Quad Flat Package) is a versatile and widely used surface-mount IC package, balancing compact design, high pin density, and reliable assembly. Its low-profile body and gull-wing leads make it ideal for consumer electronics, industrial systems, automotive modules, and embedded applications.
By understanding dimensions, footprint design, soldering methods, and common defects, engineers can optimize PCB layouts and ensure high-quality assembly. Whether for prototyping or full-scale production, LQFP remains a dependable choice for modern electronics.
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