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Thin shrink small outline package
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The Thin Shrink Small Outline Package (TSSOP) is a rectangulardorbin surface mount plastic integrated circuit (IC) package with gull-wing leads.
Application
[edit]They are suited for applications requiring 1 mm or less mounted height and are commonly used in analog and operational amplifiers, controllers and Drivers, Logic, Memory, and RF/Wireless, Disk drives, video/audio and consumer electronics.[1]
Physical properties
[edit]The Thin shrink small outline package has a smaller body and smaller lead pitch than the standard SOIC package. It is also smaller and thinner than a TSOP with the same lead count. Body widths are 3.0 mm, 4.4 mm and 6.1 mm. The lead counts range from 8 to 80 pins. The lead pitches are 0.5 or 0.65 mm.
Exposed Pad
[edit]Some TSSOP packages have an exposed pad. This is a rectangular metal pad on the bottom side of the package. The exposed pad will be soldered on the PCB to transfer heat from the package to the PCB. In most applications, the exposed pad is connected to ground.[2]
HTSSOP
[edit]The Heat sink thin shrink small outline package[3] (HTSSOP) is Texas Instruments name for a TSSOP with an exposed pad on the bottom side.[4] There are some other manufacturers who use the same name.
See also
[edit]Similar package types
[edit]References
[edit]- ^ "TSSOP in STATS ChipPAC datasheet". Retrieved 14 December 2020.
- ^ "Exposed pads: a brief introduction". www.maximintegrated.com. Retrieved 8 January 2021.
- ^ "Plastic Packages for Integrated Circuits (HTSSOP)". www.renesas.com. Retrieved 8 January 2021.
- ^ "TSSOP on mbedded ninja". mbedded ninja. Retrieved 8 June 2022.
External links
[edit]
Wikimedia Commons has media related to TSSOP integrated circuit packages.
Thin shrink small outline package
View on Grokipediafrom Grokipedia
The Thin Shrink Small Outline Package (TSSOP) is a rectangular, surface-mount plastic integrated circuit (IC) package featuring gull-wing leads on two opposite sides, designed for compact, low-profile applications with a typical body thickness of 0.9 mm and lead pitches ranging from 0.4 mm to 0.65 mm.[1] It supports pin counts from 8 to 56 (and up to 80 in some variants), enabling higher integration density compared to standard Small Outline Integrated Circuit (SOIC) or Small Outline Package (SOP) types, while maintaining a molded construction with solder-plated leads for reliable surface mounting.[1][2]
TSSOP packages adhere to JEDEC standards and are available in body widths of 3.0 mm, 4.4 mm, or 6.1 mm, making them suitable for high-volume production with options for copper wire interconnects and exposed pad configurations to enhance thermal performance.[1][3] Their thin profile—under 1 mm in height—reduces overall weight and board space, offering advantages in shorter lead lengths that minimize electrical crosstalk and improve signal integrity in dense circuits.[3][4]
Commonly used in portable electronics, automotive systems, and computing peripherals, TSSOPs provide a cost-effective solution for applications requiring greater board density without compromising performance, though their fine pitch demands precise soldering techniques and may necessitate specialized inspection tools like X-ray for quality assurance.[2][4] They are RoHS-compliant with lead-free options and green materials, supporting environmental standards in modern manufacturing.[3]
This table illustrates key dimensional and performance trade-offs, with data normalized for comparability; actual values vary by manufacturer.[53][3][55]
Overview
Definition and Characteristics
The Thin Shrink Small Outline Package (TSSOP) is a rectangular surface-mount plastic integrated circuit (IC) package characterized by gull-wing shaped leads extending from two opposite sides. This design enables direct mounting onto the surface of a printed circuit board (PCB) without the need for through-hole insertion, facilitating higher component density in electronic assemblies.[5][2] Key characteristics of the TSSOP include its compact size tailored for space-constrained applications, a thinner profile typically measuring 1.0 mm or less in height compared to broader small outline packages, and lead pitches of 0.5 mm or 0.65 mm. These attributes make it well-suited for automated assembly using surface-mount technology (SMT), where the package's low profile and fine pitch allow for efficient reflow soldering and minimal board real estate usage.[6][1] In terms of basic operational traits, the TSSOP supports reliable signal integrity for low- to medium-pin-count devices, accommodating 8 to 80 pins, with the gull-wing leads serving dual purposes of mechanical support and electrical interconnection to the PCB. The package is standardized by the Joint Electron Device Engineering Council (JEDEC) under outline MO-153, which defines variations for body widths of 3.0 mm, 4.4 mm, or 6.1 mm to accommodate different device requirements.[1][7]History and Evolution
The Thin Shrink Small Outline Package (TSSOP) emerged in the early 1990s as an advancement over earlier surface-mount packages like the Small Outline Integrated Circuit (SOIC) and Shrink Small Outline Package (SSOP), addressing the growing need for reduced height and footprint in compact electronics.[8] This evolution was spurred by the rapid expansion of portable consumer devices, where space constraints demanded components with profiles under 1.2 mm to fit into slim designs for emerging mobile phones and laptop computers.[8] By 1993, TSSOP had gained recognition as a viable standard for logic, analog, and memory ICs, reflecting the industry's shift toward higher-density surface-mount technology (SMT) to lower assembly costs and improve board efficiency.[8] Key introductions by major semiconductor manufacturers marked the package's adoption in the mid-1990s. Integrated Device Technology (IDT) pioneered TSSOP integration for high-speed Fast CMOS (FCT) octal logic products in 1994, enabling better performance in space-limited applications.[8] Texas Instruments followed in 1995 with the launch of its 20-pin TSSOP PowerPAD variant, which incorporated an exposed thermal pad to enhance heat dissipation while maintaining the thin profile.[9] NXP Semiconductors (formerly Philips) offered TSSOP configurations for a range of analog and logic devices, contributing to its proliferation in automotive and consumer sectors. These efforts were driven by the surge in demand for low-profile packaging amid the 1990s boom in portable electronics, where miniaturization became essential for battery-powered systems and high-frequency operations.[8] Standardization accelerated broader industry uptake in the mid-1990s, with JEDEC registering the TSSOP under outline MO-153 around 1996 to define precise dimensions, lead pitches (typically 0.65 mm or 0.5 mm), and material specifications for interoperability, building on earlier EIAJ guidelines for similar shrink packages.[10] This formalization ensured compatibility across global manufacturers, facilitating supply chain efficiency.[8] In the early 2000s, TSSOP evolved further with variants emphasizing thermal management, such as enhanced exposed pad designs, to support higher-power ICs in demanding environments like telecommunications and computing peripherals.[9] These advancements maintained the core thin, gull-wing leaded structure while adapting to escalating performance requirements in an era of increasing device complexity.[8]Design and Specifications
Physical Dimensions and Lead Configuration
The Thin Shrink Small Outline Package (TSSOP) is characterized by a compact rectangular body designed for surface-mount applications, with standard body widths of 3.0 mm (narrow), 4.4 mm (medium), and 6.1 mm (wide) to accommodate varying pin densities. The package height is typically 1.0 mm to 1.2 mm maximum, while the body length varies based on pin count, ranging from about 4.9 mm for 8-pin devices to 12.5 mm for 48-pin or higher configurations.[11] These dimensions ensure compatibility with automated assembly and are defined under JEDEC standard MO-153 for consistency across manufacturers.[1][6][12] Lead configuration in TSSOP features gull-wing style leads extending from the two longer opposite sides of the package, arranged symmetrically with pitches of 0.65 mm for standard variants or 0.50 mm for fine-pitch options. Lead counts range from 8 to 80 pins, with lead thickness measuring 0.15 mm to 0.20 mm and a coplanarity tolerance of 0.10 mm to support reliable reflow soldering and minimize defects.[13][13] Pinout standards follow a sequential numbering scheme starting at pin 1, typically marked by a molded dot or chamfer on the package corner nearest the first lead, with numbering proceeding counterclockwise along the lead rows from one end to the other. For PCB integration, recommended land patterns adhere to IPC-7351 guidelines, which specify pad dimensions and solder joint geometries optimized for reflow processes, such as pad widths of 0.30 mm to 0.40 mm and toe lengths of 0.60 mm to 0.80 mm depending on density level.[13][14]| Parameter | Typical Values |
|---|---|
| Body Width | 3.0 mm, 4.4 mm, 6.1 mm |
| Body Height | 1.0–1.2 mm |
| Lead Pitch | 0.50 mm or 0.65 mm |
| Lead Count | 8–80 pins |
| Lead Thickness | 0.15–0.20 mm |
| Coplanarity Tolerance | 0.10 mm |
Materials and Manufacturing Process
The leadframe in a Thin Shrink Small Outline Package (TSSOP) is typically constructed from copper alloys, such as C194, or Alloy 42 (an iron-nickel alloy), which provide the necessary structural integrity and electrical conductivity for the package's leads.[15][16] These leadframes are plated with tin or matte tin to enhance solderability and prevent oxidation during assembly and use.[17][18] The integrated circuit (IC) die is attached to the leadframe using a thermally conductive epoxy adhesive or solder, which ensures efficient heat dissipation from the die to the package exterior.[19] Encapsulation is achieved with an epoxy molding compound (EMC), a thermoset resin that offers robust mechanical protection, moisture resistance, and electrical insulation while maintaining dimensional stability.[20][21] The manufacturing process begins with die attachment, where the IC die is bonded to the central paddle of the leadframe strip using epoxy or solder, followed by electrical interconnection via wire bonding—typically with gold or aluminum wires—or, less commonly for TSSOP, flip-chip bumping for higher-density applications.[16][22] The assembly then undergoes transfer molding, in which preheated EMC pellets are liquefied under high pressure (typically 5-10 MPa) and injected into a multi-cavity mold at temperatures around 175°C, encapsulating multiple units on the leadframe strip to form the protective body.[22] Post-molding, the strip proceeds to lead trimming and forming, where excess material is sheared and the leads are bent into the characteristic gull-wing shape for surface-mount compatibility, followed by singulation to separate individual packages.[23] Final steps include selective plating of the leads if not pre-plated, laser marking for identification, and inspection to ensure compliance with standards.[17] TSSOP production adheres to quality standards that emphasize reliability, including Moisture Sensitivity Level (MSL) classifications of 1 to 3 per JEDEC J-STD-020, which dictate safe exposure times to ambient humidity before reflow soldering to prevent issues like popcorning.[24][25] Since 2006, TSSOP packages have complied with RoHS directives by using lead-free materials, such as matte tin plating over copper leadframes, eliminating hazardous substances like lead in solders and finishes.[26] Common manufacturing defects include wire sweep, caused by mold flow forces displacing bonding wires during encapsulation, and delamination at interfaces like the die-attach or mold compound, often triggered by moisture absorption or thermal mismatch.[27][28] These are mitigated through optimized molding parameters and material selection to achieve high yields in production. The use of inexpensive leadframe bases and mature transfer molding techniques contributes to TSSOP's cost-effectiveness, making it suitable for high-volume production of consumer integrated circuits where economies of scale reduce per-unit costs to fractions of a cent.[29][30]Variants and Features
Standard TSSOP Configurations
The Thin Shrink Small Outline Package (TSSOP) offers a range of standard configurations tailored to various integrated circuit (IC) types, primarily defined by pin count, body width, and lead pitch to balance space efficiency and functionality. These baseline variants exclude thermal enhancements, focusing on compact surface-mount designs for general electronics assembly. Standardization through JEDEC ensures consistent dimensions across manufacturers, facilitating interoperability in production. Pin count variants in standard TSSOP packages typically range from 8 to 64 leads, with common selections aligned to IC complexity. Configurations with 8 to 16 pins are suited for simple logic devices and gates, such as inverters or buffers, where minimal I/O requirements allow for smaller footprints. For operational amplifiers (op-amps) and controllers, 20 to 28 pins provide adequate connectivity for dual or quad-channel designs and basic signal processing. Higher counts of 48 to 64 pins accommodate microcontrollers or memory interfaces, supporting increased peripheral integration without excessive board space. Body size adaptations further customize TSSOP for density and pin capacity needs. Narrow bodies at 3 mm width are optimized for high-density printed circuit boards (PCBs), ideal for space-constrained applications with lower pin counts. Medium 4.4 mm widths serve general analog ICs, offering a versatile balance for mid-range pin configurations. Wider 6.1 mm bodies support higher pin counts, enabling more complex routing while maintaining a thin profile. Lead pitch options include 0.65 mm for cost-sensitive designs, providing reliable solderability in standard automated assembly processes, and 0.5 mm for compact layouts requiring finer spacing. A representative example is the 14-pin TSSOP at 0.65 mm pitch and 4.4 mm body width, commonly used for logic ICs like multiplexers or comparators. These pitches ensure compatibility with prevalent PCB fabrication tolerances. JEDEC standard MO-153 defines the outlines for these configurations, with variations such as AB for 14-lead packages ensuring precise tolerances for lead coplanarity and body dimensions. This standardization promotes adoption by major manufacturers including Texas Instruments, NXP Semiconductors, and ON Semiconductor, who adhere to these specifications for consistent quality and supply chain reliability.Exposed Pad and Thermal Enhancements
The exposed pad in thin shrink small outline package (TSSOP) variants features a central copper leadframe die pad exposed on the bottom of the package, typically occupying 20-50% of the package body's area to facilitate heat spreading from the die. This pad is directly connected to the die attach paddle, enabling efficient thermal conduction, and is often electrically tied to ground or Vss for additional functionality in circuit design.[31] These enhancements significantly improve thermal performance by reducing the junction-to-ambient thermal resistance (θ_JA), often by 20-60% compared to standard TSSOP packages, through integration with PCB features like vias to internal copper planes. The thermal resistance is defined by the equation θ_JA = (T_J - T_A) / P, where T_J is the junction temperature, T_A is the ambient temperature, and P is the power dissipation; with exposed pad designs, θ_JA can decrease from approximately 100°C/W in unmodified TSSOP to around 50°C/W or lower, depending on board layout and airflow.[31][32] Implementation involves soldering the exposed pad to a corresponding thermal land on the PCB, using via-in-pad configurations (e.g., 0.33 mm diameter vias) to transfer heat to inner layers or planes, which requires careful moisture sensitivity level (MSL) handling to avoid pad oxidation during storage and assembly. Variants such as EP-TSSOP, incorporating the exposed pad, are available in 8- to 38-pin configurations[31] and are commonly applied in power management integrated circuits to support higher dissipation levels. Higher pin counts up to 48 are available from other manufacturers.[33]Applications and Performance
Primary Uses in Electronics
The Thin Shrink Small Outline Package (TSSOP) is widely employed for packaging various integrated circuits (ICs) that require compact surface-mount configurations. In analog applications, it commonly houses operational amplifiers (op-amps) such as the AD8630 quad op-amp, which supports precision signal conditioning in sensor interfaces.[34] Comparators like the LM393 dual differential comparator also utilize TSSOP for voltage comparison tasks in low-power circuits.[35] For digital logic, TSSOP accommodates components including flip-flops and gates; for instance, the SN74AHCT273 octal D-type flip-flop with clear is available in this package, facilitating data storage and synchronization in control systems.[36] Buffers such as the SN74HC244 octal buffer with 3-state outputs are similarly packaged, enabling efficient bus interfacing and address driving for memory systems.[37] Mixed-signal ICs benefit from TSSOP's form factor, with analog-to-digital converters (ADCs) like the ADS7960-Q1 12-bit SAR ADC in 30-pin TSSOP serving data acquisition needs.[38] Digital-to-analog converters (DACs), including the DAC8871 16-bit voltage-output DAC in 16-pin TSSOP, support signal generation in embedded applications.[39] Low-power microcontrollers, such as the MSP430G2x53 series in 20- or 28-pin TSSOP, integrate these functions for sensor processing and portable control.[40] In consumer electronics, TSSOP-packaged ICs drive audio and video functions in smartphones and wearables, where their low profile enables slim designs; for example, DACs and op-amps handle signal processing in portable media devices.[39] Automotive systems deploy TSSOP for sensors and controllers under strict height constraints of 1 mm or less, as seen in ADCs for vehicle diagnostics and microcontrollers for engine management.[38] In computing, these packages support memory buffers and disk drive interfaces through logic buffers that manage data lines in storage peripherals.[37] TSSOP integrates seamlessly via surface-mount assembly on multi-layer printed circuit boards (PCBs), promoting high-density layouts in space-constrained assemblies.[5] Its suitability for battery-powered devices stems from the compact form that minimizes board real estate while supporting low-power IC operation.[40] Adoption of TSSOP has grown for mid-range pin counts (typically 8 to 48 pins), where it offers a balance between simplicity and density, supplanting obsolete through-hole DIP packages while avoiding the complexity of leadless QFN alternatives.[5]Advantages and Limitations
The Thin Shrink Small Outline Package (TSSOP) offers significant space-saving benefits due to its reduced profile, being significantly thinner than the standard Small Outline Integrated Circuit (SOIC) package, which enables higher component density on printed circuit boards. This thinner design, typically 0.9 mm (maximum 1.2 mm) in body height compared to SOIC's maximum 1.75 mm, facilitates compact layouts in space-constrained applications. Additionally, TSSOP is cost-effective for leadframe-based production, providing a low-cost solution suitable for high-volume manufacturing.[3] Its gull-wing leads contribute to good electrical performance through relatively low inductance, typically in the range of 5-10 nH per lead, supporting efficient signal transmission.[41] Compared to ball grid array (BGA) packages, TSSOP allows easier visual inspection and rework due to the exposed leads, simplifying assembly and maintenance processes.[42] Despite these strengths, TSSOP has limitations in thermal management, particularly without an exposed pad, where junction-to-ambient thermal resistance (θ_JA) often exceeds 80°C/W—such as 103.5°C/W for a 16-pin configuration—making it less ideal for high-power integrated circuits that require efficient heat dissipation.[43] Scalability for higher pin counts is constrained compared to quad flat no-lead (QFN) packages, as TSSOP typically maxes out around 56 pins with increased routing complexity.[44] The package is also vulnerable to mechanical stress on flexing boards, where the gull-wing leads can experience bending or fatigue under vibration or thermal cycling.[45] TSSOP demonstrates strong reliability in harsh environments, supporting operating temperatures from -40°C to 125°C, as verified in numerous industrial-grade devices. Common failure modes, such as lead cracking from thermal expansion mismatch, are effectively mitigated by matte tin plating on the leads, which enhances ductility and prevents tin whisker growth. In terms of performance, TSSOP maintains signal integrity for frequencies up to 100 MHz, with minimal distortion from lead inductance in well-designed layouts.[42] Power handling capability reaches 1-2 W when paired with appropriate PCB thermal vias and copper area, though this depends on ambient conditions and device specifics.[9] These attributes make TSSOP suitable for consumer devices requiring balanced size and performance.[42]Comparisons
Versus SOIC and TSOP
The Thin Shrink Small Outline Package (TSSOP) differs from the Small Outline Integrated Circuit (SOIC) primarily in its reduced profile, offering a body thickness of approximately 1.0 mm compared to the SOIC's 1.75 mm, resulting in a 30-40% thinner package that enables greater density in height-constrained applications.[46][13] For the same pin count, such as in 8- or 16-lead configurations, the TSSOP features a similar body width (typically 4.4 mm versus narrow SOIC's 3.9 mm) and shorter length, while maintaining a surface-mount gull-wing lead configuration but with a finer lead pitch of 0.65 mm versus the SOIC's standard 1.27 mm.[47][48] However, the SOIC's larger leads and greater overall mass provide superior current-handling capacity and thermal dissipation for higher-power applications, making it preferable where elevated power dissipation is required without additional thermal enhancements.[49] In comparison to the Thin Small Outline Package (TSOP), which is often optimized for memory devices, the TSSOP employs gull-wing leads extending from the longer sides of the package, facilitating better visual inspection of solder joints during assembly compared to the TSOP's typical J-lead configuration on the shorter sides.[50] While both packages achieve thin profiles around 1.0 mm, the TSSOP offers broader versatility for logic and mixed-signal integrated circuits due to its standardized long-side lead placement and compatibility with higher pin counts up to 56 or more. Functionally, the TSSOP's gull-wing leads enhance board-level reliability under vibrational stress by allowing greater flexure and stress absorption at the solder joints, outperforming J-lead designs in environments with mechanical shock; pin count ranges overlap (e.g., 28-48 leads), but the TSSOP has become the preferred choice for non-memory ICs since the early 2000s due to improved manufacturability and inspection ease.[51][52] When selecting between these packages, the TSSOP is ideal for designs prioritizing minimal height and board space, such as in portable electronics, whereas the SOIC suits legacy systems or those demanding higher thermal performance via larger leads, and the TSOP remains relevant for specialized memory modules requiring compact, short-side lead arrangements without exposed pads for heat transfer.[53][54]Versus Other Surface-Mount Packages
The Thin Shrink Small Outline Package (TSSOP) offers visible gull-wing leads that facilitate easier electrical probing, inspection, and repair compared to the Quad Flat No-Lead (QFN) package, which relies on hidden bottom pads requiring specialized equipment for access.[44] QFN packages achieve higher pin density, supporting over 64 pins in a smaller footprint—such as a 20-pin QFN occupying 15.75 mm² versus 41.60 mm² for a comparable TSSOP—making them suitable for compact designs, though they demand precise reflow soldering to avoid voids under the pads.[53] For low-pin-count applications (under 48 pins), TSSOP remains more cost-effective due to simpler leadframe construction and broader compatibility with standard assembly processes.[3] In contrast to the Mini Small Outline Package (MSOP), which serves as a miniaturized variant of TSSOP with a narrower body (typically 3 mm wide versus TSSOP's 4.4 mm) and 0.65 mm lead pitch for ultra-compact integration, TSSOP provides greater robustness for moderate power dissipation through its larger thermal mass and standard 0.65 mm pitch.[3] MSOP excels in space-constrained applications like portable devices, reducing footprint by up to 30% while maintaining similar mounted heights under 1 mm, but it sacrifices some mechanical strength and ease of handling during manual assembly.[55] Compared to Ball Grid Array (BGA) and Land Grid Array (LGA) packages, TSSOP simplifies prototyping and rework by eliminating the need for underfill materials or X-ray inspection, as its external leads allow straightforward visual verification and iron-based soldering, though it is limited to fewer than 100 pins.[56] BGA and LGA enable higher I/O counts (often exceeding 200 pins) with superior electrical performance and smaller footprints for high-density boards, but they increase assembly costs by 20-50% due to advanced reflow requirements and yield risks in fine-pitch variants.[57] Overall, TSSOP strikes a balance between cost, ease of integration, and performance for mid-range integrated circuits in consumer and industrial electronics, though industry trends since the 2010s show migration toward QFN for new designs prioritizing density and thermal efficiency in automotive and mobile applications.[58]| Attribute | TSSOP-20 | QFN-20 | MSOP-8 (typical) | BGA-64 (example) |
|---|---|---|---|---|
| Footprint (mm²) | 41.60 | 15.75 | 9.00 | 25.00-36.00 |
| Max Height (mm) | 1.20 | 1.00 | 1.10 | 1.00 |
| Lead Pitch (mm) | 0.65 | 0.50 | 0.65 | 0.80 |
| Thermal Resistance θJA (°C/W) | 69.5 | 29.9 | 100-150 | 20-30 |