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Protect Your SMD Power Product From Damaging Moisture

When it comes to mounting components to circuit boards, surface mount technology saves board space and assembly time. Advantages include higher component density, resulting in smaller circuits and faster circuit speeds, plus shock and vibration resistance, and low noise. Because of these and other benefits, surface mount-packaged (SMD) components are a logical choice for automated assembly. However moisture can cause a “popcorn effect” during solder reflow.

In order to help OEMs take proper care when handling and storing moisture-sensitive devices, the Association Connecting Electronic Indu

Protect Your SMD Power Product From Damaging Moisture

stries created the IPC-M-109 Moisture-sensitive Component Standards and Guideline Manual. Among its seven documents, IPC-M-109 defines moisture sensitivity levels (MSLs), with each numerical level corresponding to the part’s risk of incurring the popcorn effect: Level 1 is the lowest risk, and Level 6 indicates the highest risk. Each level determines how long a moisture-sensitive device can be exposed to ambient room conditions (≤30°C and 85 percent relative humidity at Level 1; all other levels: ≤30°C and 60 percent relative humidity).

Find out the Product’s Floor Life

Many vendors list MSL information under the “Environmental” section of the datasheet. For example, the datasheet for Daburn Electronics' Polytron Devices MTWA4 Series of 3.5-watt DC-DC converters for medical applications indicates they are available in a 0.95 x 0.57 x 0.40-inch miniature SMD package and carry an MSL level of 2. That means it can be stored, mounted and reflowed within one year of “floor life” outside of a moisture barrier bag at less than or equal to 30°C and 60 percent relative humidity. Should the part exceed its floor life, that moisture will have to be baked out, slowly, before assembly. In addition to their miniature size, the MTWA4 converters provide 5,000 Vac input to output 2 MOPP isolation and remote ON/OFF. Their voltage input range (4.5 to 12V DC) makes them well-suited for portable devices. The MTWA4 Series of SMD-packaged DC-DC converters is well-suited for automated assembly and can satisfy various input and output requirements.

When using a surface mount component in your design, manufacturability and reliability depend on proper storage. Be sure to check the manufacturer’s datasheet for the part’s numerical moisture sensitivity level (MSL) in order to determine its floor life, and to refer to IPC J-STD-020 and J-STD-033 for other storage and handling procedures based on the MSL. The better informed you are about moisture levels according to JEDEC/IPC standards, you’ll have more certainty that your part will perform as intended.

To learn more, get in touch with our technical staff.