SOIC vs SSOP vs TSSOP: Small Outline Package Comparison

The small outline package family dominates modern PCB designs, but choosing between SOIC, SSOP, and TSSOP can significantly impact your board’s size, assembly process, and overall manufacturability. I’ve worked with all three package types across consumer electronics, industrial controls, and automotive projects, and the right choice depends entirely on your specific constraints.

This comprehensive SOIC package comparison covers the critical differences in dimensions, lead pitch, thermal performance, and assembly requirements. Whether you’re optimizing for board space or ease of hand soldering during prototyping, understanding SSOP vs TSSOP tradeoffs helps you make informed decisions early in your design cycle.

Understanding the Small Outline Package Family

The small outline package family evolved from the need to replace bulky through-hole DIP packages with surface mount alternatives. All three packages share the same fundamental architecture: a rectangular plastic body with gull-wing leads extending from two opposite sides. The differences lie in their dimensions, lead pitch, and package height.

What is an SOIC Package?

The SOIC package (Small Outline Integrated Circuit) represents the original surface mount adaptation of the DIP package. It occupies 30-50% less board area than an equivalent DIP while maintaining the same pin-outs, making migration from through-hole to surface mount straightforward.

Key SOIC package characteristics include a 1.27mm (50 mil) lead pitch, which provides excellent tolerance for automated assembly and remains manageable for hand soldering. Body widths follow JEDEC standards, with narrow body (3.9mm) and wide body (7.5mm) being most common. The package height typically ranges from 1.5mm to 1.75mm.

SOIC naming conventions follow the format SO-N or SOIC-N, where N indicates pin count. An SOIC-16, for example, has 16 pins arranged in two rows of 8.

What is an SSOP Package?

SSOP (Shrink Small Outline Package) reduces the SOIC footprint by tightening the lead pitch and compressing the body dimensions. The “shrink” designation accurately describes its purpose: achieving higher pin density in less board space.

The standard SSOP lead pitch is 0.65mm (25.6 mil), roughly half the SOIC pitch. Body widths typically come in 150 mil (3.8mm), 209 mil (5.3mm), and 300 mil (7.6mm) variants. Package height ranges from 1.65mm to 1.85mm, similar to SOIC.

SSOP packages support pin counts from 8 to 64, enabling complex ICs in compact form factors. The tighter pitch demands more precise assembly processes but rewards designers with significant space savings.

What is a TSSOP Package?

TSSOP (Thin Shrink Small Outline Package) combines the reduced pitch of SSOP with a dramatically thinner profile. As the name suggests, “thin” is the distinguishing feature—package height drops to 0.9mm to 1.2mm, roughly half the thickness of standard SOIC or SSOP.

TSSOP lead pitch is typically 0.65mm, matching SSOP, though 0.5mm variants exist for higher density applications. Body widths come in 3.0mm, 4.4mm, and 6.1mm options, conforming to JEDEC standards. Pin counts range from 8 to 80.

The thin profile makes TSSOP essential for applications with strict height constraints—smartphones, tablets, thin laptops, and other portable devices where every millimeter matters.

SOIC vs SSOP vs TSSOP: Complete Specification Comparison

Understanding the dimensional differences helps you make the right package selection.

Lead Pitch and Pin Density Impact

The lead pitch difference between SOIC package and its shrink variants fundamentally changes PCB design requirements.

With SOIC’s generous 1.27mm pitch, you can route traces between pads on a two-layer board without difficulty. The 0.65mm pitch of SSOP and TSSOP typically requires either finer trace/space rules or additional PCB layers for escape routing.

Size and Footprint Comparison

Board space savings drive many decisions in the SSOP vs TSSOP selection process.

Footprint Area by Pin Count

Moving from SOIC to SSOP typically saves 25-35% board area. TSSOP provides an additional 15-25% reduction over SSOP. For designs with dozens of ICs, these savings compound significantly.

Height Profile Considerations

Package height becomes critical in space-constrained applications:

TSSOP’s sub-1.2mm profile enables designs impossible with thicker packages. For stacked PCB assemblies or products with tight enclosure constraints, TSSOP often becomes the only viable option.

Assembly and Soldering Comparison

Assembly complexity increases as package dimensions shrink. Understanding these tradeoffs helps balance design goals against manufacturing realities.

Hand Soldering Feasibility

From a practical standpoint, the SOIC package remains the most accessible for prototyping and rework:

SOIC’s 1.27mm pitch provides comfortable margins for manual work. The “lake of solder and wick” technique works reliably even with modest soldering skills. For SSOP and TSSOP, the same technique applies but requires steadier hands and better optical aids.

Automated Assembly Considerations

Production assembly differs in process requirements:

SOIC Package Assembly:

• Standard stencil thickness (0.125-0.15mm) works well
• Wide process window for paste deposition
• Forgiving placement accuracy (±0.1mm acceptable)
• Visual inspection straightforward

SSOP Assembly:

• Finer stencil apertures required
• Tighter paste volume control
• Placement accuracy ±0.05mm recommended
• Increased bridging risk during reflow

TSSOP Assembly:

• Precision stencils essential (laser-cut recommended)
• Careful paste volume optimization
• Placement accuracy ±0.05mm or better
• Height profile requires attention during handling

Solder Bridging Risk

The tighter pitch of shrink packages increases solder bridge probability:

Electrical Performance Characteristics

Package geometry influences electrical behavior, particularly at higher frequencies.

Parasitic Inductance and Capacitance

Shorter leads in shrink packages reduce parasitic effects:

For applications above 50-100MHz, the reduced lead inductance of TSSOP provides measurable signal integrity benefits. The shorter interconnect paths between die and PCB minimize parasitic effects that can cause ringing, overshoot, and EMI issues.

Frequency Performance Guidelines

Thermal Management Comparison

Heat dissipation capabilities vary across the small outline package family.

Standard Package Thermal Performance

Without exposed thermal pads, all three packages rely on lead conduction for heat transfer:

For ICs dissipating more than 0.5-1W, standard small outline packages may prove inadequate without additional thermal management strategies.

Enhanced Thermal Variants

Several thermal-enhanced variants address power dissipation needs:

These variants include an exposed metal pad on the package underside, providing a direct thermal path from die to PCB. PCB design must include a matching thermal pad with via connections to internal copper planes.

When selecting complex ICs like Altera FPGA devices, thermal considerations often drive package selection toward exposed-pad variants or larger packages entirely.

Application Selection Guidelines

Different applications favor different package choices.

When to Choose SOIC Package

The SOIC package remains optimal for:

• Prototype development: Easy hand soldering and rework
• Low-frequency applications: General-purpose logic, power management
• Industrial equipment: Robust, well-characterized package
• Cost-sensitive designs: Mature package with established supply chain
• Designs requiring inspectability: Large leads simplify visual QC
• Mixed through-hole/SMT boards: Easier assembly process integration

When to Choose SSOP

SSOP provides the right balance for:

• Moderate space constraints: Meaningful size reduction over SOIC
• Consumer electronics: Established package for telecom, disc drives, audio
• Designs with 16-48 pin ICs: Sweet spot for pin count vs. footprint
• Mid-volume production: Assembly processes well understood
• Applications requiring moderate frequency performance: Signal processing, data conversion

When to Choose TSSOP

TSSOP becomes essential when:

• Height restrictions exist: Sub-1.2mm profile required
• Maximum density needed: Smallest footprint in dual-row format
• High-frequency operation: Best electrical performance in SOP family
• Portable devices: Smartphones, tablets, wearables
• Multi-layer PCB available: Escape routing needs additional layers
• Automated inspection available: Hidden solder fillets harder to verify visually

Package Selection by Industry

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PCB Design Considerations

Each package type imposes different PCB design requirements.

Land Pattern Guidelines

Follow IPC-7351 recommendations for land patterns:

Routing and Layer Requirements

Useful Resources for Small Outline Package Design

These resources support successful SOIC, SSOP, and TSSOP implementation:

Component Libraries:

• Ultra Librarian: Verified footprints and 3D models
• SnapEDA: Symbol and footprint downloads
• Manufacturer websites: Package drawings and land patterns

Industry Standards:

• JEDEC MS-012: SOIC narrow body
• JEDEC MS-013: SOIC wide body
• JEDEC MO-118, MO-150: SSOP specifications
• JEDEC MO-153: TSSOP specifications
• IPC-7351: Land pattern design guidelines

Assembly Guidelines:

• IPC-A-610: Acceptability of electronic assemblies
• J-STD-001: Soldering requirements
• Manufacturer application notes: Package-specific guidance

Design Tools:

• IPC-7351 Land Pattern Calculator
• Saturn PCB Toolkit
• Manufacturer footprint generators

Frequently Asked Questions About SOIC, SSOP, and TSSOP

What is the main difference between SOIC and SSOP packages?

The primary difference is lead pitch. SOIC uses 1.27mm (50 mil) pitch while SSOP uses 0.65mm (25.6 mil) pitch. This tighter spacing allows SSOP to fit more pins in a smaller footprint or achieve smaller packages at the same pin count. SSOP typically saves 25-35% board area compared to equivalent SOIC packages. However, the finer pitch makes SSOP more challenging for hand soldering and requires more precise automated assembly processes.

Is TSSOP easier or harder to solder than SSOP?

TSSOP and SSOP have the same lead pitch (typically 0.65mm), so the soldering difficulty is similar from a pin spacing perspective. However, TSSOP’s thinner profile (0.9-1.2mm vs 1.65-1.85mm) can make handling slightly more challenging during manual assembly. The thinner package also has less thermal mass, which affects heat distribution during soldering. For hand soldering, both require good technique, flux, and adequate magnification. The main challenge with both packages compared to SOIC is the reduced margin for error due to the tighter pitch.

Can I replace an SOIC with an SSOP or TSSOP of the same pin count?

No, these packages are not directly interchangeable despite having the same pin count. The different lead pitches and body dimensions mean the PCB footprints are completely different. Replacing an SOIC-16 with an SSOP-16 or TSSOP-16 requires a new PCB layout with updated land patterns. Some manufacturers offer the same IC in multiple package options, but you must design your PCB specifically for the package you intend to use. Always verify package availability before finalizing your design.

Which small outline package has the best thermal performance?

Among standard (non-thermal-enhanced) variants, SOIC typically offers the best thermal performance due to larger lead cross-sections that conduct more heat to the PCB. However, all standard small outline packages have relatively poor thermal resistance (80-150°C/W) because they rely solely on lead conduction. For applications requiring better thermal management, choose thermal-enhanced variants like HTSSOP (TSSOP with exposed pad) or HSOIC, which include an exposed metal pad that solders directly to a PCB thermal pad. These variants can reduce thermal resistance by 30-50%.

What PCB layer count do I need for TSSOP packages?

While technically possible on two-layer boards, TSSOP packages typically benefit from four or more PCB layers. The 0.65mm (or 0.5mm) lead pitch leaves minimal space between pads for trace routing. With only two layers, escape routing becomes very challenging, especially for higher pin counts. Four-layer boards allow signal traces on outer layers with power and ground planes inside, simplifying routing while improving signal integrity. For TSSOP packages with 28+ pins or fine-pitch variants, six layers may be appropriate depending on your routing density requirements.