Information

5 Handling

5.1 MSL level

5 Handling

Several procedures have to be followed when packaging, storing and processing

( assembling) SMD technology DC/DC voltage regulators. The J-STD-020 standard from

the US JEDEC organization is referred to and applied for this purpose.

5.1 MSL level

The moisture sensitivity level (MSL) is a specification related to the moisture sensitivity

of non-hermetically sealed SMD components, which tend to absorb moisture due to

their construction. The components are classified (Tab. 5.1), whereby it is apparent in

which period e.g. a voltage regulator has to be processed without any problems in the

soldering process. The specified time and the conditions apply for permissible storage

without the relevant protective measures against ambient humidity.

MSL value Time Condition

1 unlimited 30 °C/85% RH

2 1 year 30 °C/60% RH

2a 4 weeks 30 °C/60% RH

3 168 hours 30 °C/60% RH

4 72 hours 30 °C/60% RH

5 48 hours 30 °C/60% RH

5a 24 hours 30 °C/60% RH

6 TOL (time on label) 30 °C/60% RH

Tab. 5.1: MSL classification and processing time for opened bag (J-STD-033C)

The background to classification and labeling of the components with the MSL level is

the fact that moisture can penetrate encapsulated components. This is caused by the

hygroscopicity of the plastic and the enclosed moisture can suddenly vaporize during

reflow-soldering of the regulator at soldering temperature >210 °C. This can lead to

cracks arising or the components bursting – the popcorn effect!

The relevant tests, e.g. multiple soldering, functional testing, ultrasound or CT investi-

gations, are performed by the manufacturer in order to correctly classify the compo-

nent with a MSL. These tests are defined in the JEDEC standard. The MSL determined

(e.g. MSL-3) is specified by the manufacturer in the datasheet and on the bag and has

to be considered in processing.

5.2 Packing/treatment

MagI³C power modules from Würth Elektronik eiSos GmbH & Co.KG are stored/shipped

in a Dry Pack (specially antistatic, water vapor-impermeable, flexible, ESD-resistant

bag) and are provided with an MSL level information sticker (see Fig. 5.1).

Moisture sensitivity

level

Popcorn effect

Dry packing

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5 Handling 5.1 MSL level 5 Handling Several procedures have to be followed when packaging, storing and processing (assembling) SMD technology DC/DC voltage regulators. The J-STD-020 standard from the US JEDEC organization is referred to and applied for this purpose. 5.1 MSL level The moisture sensitivity level (MSL) is a specification related to the moisture sensitivity of non-hermetically sealed SMD components, which tend to absorb moisture due to their construction. The components are classified (Tab.
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5 Handling 5.2 Packing/treatment Fig. 5.1: Example: bag label for power module article no.: 171 012 401 If the complete unit quantity of the opened bag cannot be processed within the timeframe specified in the MSL level, e.g. 168 hours for MSL-3, there is the option of resealing the components in a Dry Pack bag. As soon as the component is repacked air-tight, the remaining period for the MSL time specification not expired is available for another production period.
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5 Handling 5.2 Packing/treatment Fig. 5.2: Humidity indicator card In addition, to avoid moisture, a desiccant is included, which may consist of silica gel (Fig. 5.3), siliceous earth or a molecular sieve. Fig. 5.