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Littelfuse
MSL Classification

MSL Classification

Product catalog summary

Introduction
Littelfuse provides overvoltage, overcurrent, and overtemperature circuit protection devices, particularly for portable medical products. This document introduces the Moisture Sensitivity Level (MSL) classification for these devices.

Moisture Level Classification and Floor Life
The MSL classification determines the handling and storage requirements for non-hermetic solid-state surface-mount devices to prevent damage during assembly. The classification levels range from 1 to 6, with specific time and environmental conditions for each level. For example, Level 1 has unlimited floor life at ≤ 30°C/85% RH, while Level 2a requires assembly within 4 weeks at ≤ 30°C/60% RH.

IPC/JEDEC J-STD-020C Standard
This standard is used to classify devices based on moisture sensitivity and reflow conditions. It includes a lead-free reflow profile with a peak temperature of 250°C on the package surface. Devices are classified to ensure they are packaged, stored, and handled correctly to avoid damage during solder reflow.

Product Classification
Most Littelfuse circuit protection products are classified as MSL Level 1, indicating low moisture sensitivity. However, surface-mount PolySwitch and PolyZen devices are classified as MSL Level 2a, requiring assembly within 4 weeks of opening the moisture barrier bag. If this period is exceeded, a rebake is necessary.

Product Type MSL Classification
The document provides a table listing various Littelfuse products and their respective MSL classifications. For instance, PolySwitch femtoSMD and picoSMD devices are classified as Level 1, while PolySwitch nanoSMD, microSMD, and miniSMD devices are classified as Level 2a.

Notice
The information is deemed accurate, but users must independently evaluate the suitability of products for their applications. Littelfuse products are not intended for critical applications such as military or medical devices unless specified in the documentation. Warranties are void for unintended uses, and Littelfuse is not liable for damages from such uses.

Catalog excerpts

Introducing MSL Classification Littelfuse overvoltage, overcurrent and overtemperature circuit protection devices help designers provide effective protection for the portable medical products. Littelfuse* Expertise Applied | Answers Delivered

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The IPC/JEDEC J-STD-020C Moisture/Reflow Sensitivity Classification for Non-Hermetic Solid State Surface-Mount Devices standard is used to determine what classification level should be used for initial reliability qualification. Once identified, the surface-mount devices can be properly packaged, stored and handled to avoid subsequent thermal and mechanical damage during the assembly solder reflow attachment and/or repair operation. The standard is based upon several conditions including relative humidity and uses a lead-free reflow profile that results in a 250°C temperature (+0/-5°C) on the...

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