Technical Summary: Plastic Small Outline and Shrink Small Outline Packages

Overview

The plastic Small Outline Package (SOP) and Shrink Small Outline Package (SSOP) families are widely used in surface-mount technology (SMT) for integrated circuits and discrete components. These packages are designed to provide a compact footprint while maintaining reliable electrical and mechanical performance. The SOP and SSOP variants listed here cover a range of lead counts (14 to 28 leads) and body widths (3.9 mm to 7.5 mm for SOP, 5.3 mm for SSOP), making them suitable for various applications in consumer electronics, industrial systems, and telecommunications.

These packages are constructed from high-quality plastic materials, ensuring durability and resistance to environmental stressors such as moisture and thermal cycling. Their standardized dimensions and lead configurations facilitate ease of assembly and compatibility with automated pick-and-place equipment.

Features

• Compact Design: Optimized for space-constrained PCB layouts with body widths as narrow as 3.9 mm (SOP) and 5.3 mm (SSOP).
• Lead Count Variants: Available in 14, 16, 20, 24, and 28-lead configurations to accommodate diverse circuit complexity.
• Surface-Mount Compatibility: Designed for SMT assembly processes, enabling high-volume manufacturing efficiency.
• Robust Construction: Plastic molding ensures mechanical strength and resistance to environmental factors.
• Thermal Performance: Adequate heat dissipation properties for moderate-power applications.
• Standardized Footprints: Consistent lead pitch and dimensions for compatibility with industry-standard PCB layouts.

Applications

These packages are versatile and find use in a broad spectrum of electronic systems, including but not limited to:

• Consumer Electronics: Smartphones, tablets, wearables, and audio devices where space efficiency is critical.
• Industrial Automation: Control systems, sensors, and motor drivers requiring reliable SMT components.
• Telecommunications: Networking equipment, routers, and baseband modules.
• Automotive Electronics: Infotainment systems, engine control units (ECUs), and lighting modules.
• Medical Devices: Portable diagnostic equipment and patient monitoring systems.

Electrical Characteristics

While the electrical performance of the packaged device depends on the specific IC or component housed within, the SOP and SSOP packages themselves are designed to minimize parasitic effects and ensure signal integrity. Key electrical considerations include:

• Lead Inductance: Low parasitic inductance due to short lead lengths, suitable for high-frequency applications.
• Capacitance: Minimal inter-lead capacitance to reduce crosstalk in high-speed circuits.
• Current Handling: Leads are rated for typical currents up to 500 mA, depending on the specific package and lead material.
• Insulation Resistance: High resistance (>1 GΩ) between adjacent leads to prevent leakage currents.

Package Information

Dimensional Specifications

Below are the detailed dimensions for each package variant:

• SOT108-1 (14 leads, SOP): Body width = 3.9 mm, lead pitch = 0.65 mm (typical).
• SOT109-1 (16 leads, SOP): Body width = 3.9 mm, lead pitch = 0.65 mm.
• SOT162-1 (16 leads, SOP): Body width = 7.5 mm, lead pitch = 1.27 mm.
• SOT163-1 (20 leads, SOP): Body width = 7.5 mm, lead pitch = 1.27 mm.
• SOT137-1 (24 leads, SOP): Body width = 7.5 mm, lead pitch = 1.27 mm.
• SOT136-1 (28 leads, SOP): Body width = 7.5 mm, lead pitch = 1.27 mm.
• SOT337-1 (14 leads, SSOP): Body width = 5.3 mm, lead pitch = 0.65 mm.
• SOT338-1 (16 leads, SSOP): Body width = 5.3 mm, lead pitch = 0.65 mm.
• SOT339-1 (20 leads, SSOP): Body width = 5.3 mm, lead pitch = 0.65 mm.
• SOT340-1 (24 leads, SSOP): Body width = 5.3 mm, lead pitch = 0.65 mm.
• SOT341-1 (28 leads, SSOP): Body width = 5.3 mm, lead pitch = 0.65 mm.
• SOT27-1 (DIP): Dual In-line Package with through-hole mounting, lead pitch = 2.54 mm.

Material and Finish

All SOP and SSOP packages are constructed from high-temperature, flame-retardant plastic (typically UL94 V-0 rated). The leads are made of copper alloy with a tin or lead-free finish (e.g., matte tin or nickel-palladium-gold) to ensure solderability and corrosion resistance.

Thermal Properties

• Operating Temperature Range: -40°C to +125°C (standard industrial range).
• Thermal Resistance (θ_JA): Varies by package size; typical values range from 50°C/W to 120°C/W.
• Moisture Sensitivity Level (MSL): MSL 3 or better, indicating limited exposure tolerance to ambient moisture before baking is required.

Assembly and Handling Guidelines

To ensure optimal performance and reliability during PCB assembly, adhere to the following guidelines:

• Storage: Store in a dry environment (<40% relative humidity) with anti-static precautions.
• Reflow Profile: Follow JEDEC J-STD-020 reflow soldering profiles, ensuring peak temperatures do not exceed 260°C for lead-free finishes.
• PCB Land Patterns: Use manufacturer-recommended land patterns to avoid tombstoning or misalignment.
• ESD Protection: Handle with ESD-safe equipment to prevent damage to sensitive components.

Conclusion

The SOP and SSOP package families provide a reliable and compact solution for modern surface-mount applications. With a range of lead counts and body widths, these packages cater to diverse design requirements while maintaining high standards of electrical and mechanical performance. Their compatibility with automated assembly processes and robust material properties make them a preferred choice for engineers across industries.