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MSL Levels 1 to 6: Floor Life and Soak Conditions Table

Moisture trapped in a plastic package can crack it or delaminate it during reflow. The moisture sensitivity level tells you how long a part may sit out of its dry bag before it must be baked. This table gives the floor life and soak conditions for each level so operators and planners can check them at a glance.

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Item	Parameter	Value	Note
MSL 1	Floor life	Unlimited at 30 C / 85% RH or below	No dry pack required
MSL 1	Soak (qualification)	85 C / 85% RH for 168 hours
MSL 2	Floor life	1 year at 30 C / 60% RH or below
MSL 2	Soak (qualification)	85 C / 60% RH for 168 hours
MSL 2a	Floor life	4 weeks at 30 C / 60% RH or below
MSL 2a	Soak (qualification)	30 C / 60% RH for 696 hours
MSL 3	Floor life	168 hours at 30 C / 60% RH or below	Common level for BGAs and QFPs
MSL 3	Soak (qualification)	30 C / 60% RH for 192 hours
MSL 4	Floor life	72 hours at 30 C / 60% RH or below
MSL 4	Soak (qualification)	30 C / 60% RH for 96 hours
MSL 5	Floor life	48 hours at 30 C / 60% RH or below
MSL 5	Soak (qualification)	30 C / 60% RH for 72 hours
MSL 5a	Floor life	24 hours at 30 C / 60% RH or below
MSL 5a	Soak (qualification)	30 C / 60% RH for 48 hours
MSL 6	Floor life	Time on label (TOL)	Must be baked before use, reflow within the time on the label
MSL 6	Soak (qualification)	Mandatory bake before use
Floor life clock	Starts	When the moisture barrier bag is opened or the part leaves dry storage	Track per reel, tray or tube
Moisture barrier bag	Minimum shelf life	12 months at below 40 C / 90% RH	Per J-STD-033 guidance
Humidity indicator card	Purpose	Shows RH inside the bag when opened	Read it at opening and record the result
Label	Required content	MSL level, peak reflow body temperature, floor life, bake information	Check the label, not the datasheet alone
Peak body temperature	Why it matters	MSL is rated at a stated peak package temperature	Lead-free reflow is hotter than tin-lead, so ratings can differ

Values summarise J-STD-020 (classification) and J-STD-033 (handling, packing and shipping). Bake times depend on package thickness and prior exposure and are given in J-STD-033, so they are not listed here. Always follow the component maker's label.

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How to use the table

Find the MSL printed on the moisture barrier bag label, then look up the floor life. The clock starts when the bag is opened. A level 3 part has 168 hours at or below 30 C and 60% relative humidity. If a reel is partly used and returned to a dry cabinet, the exposure time already used still counts unless a bake resets the clock according to J-STD-033. Search for a level or the word floor to narrow the list, then export for a line-side reference sheet.

Why the soak conditions matter

The soak column shows the preconditioning used when the part maker qualifies a package to a level, for example 192 hours at 30 C and 60% RH for level 3. Those conditions represent the moisture the part absorbs during its allowed floor life. You do not repeat the soak in production. You rely on the label, and you protect parts by limiting exposure and storing them in dry cabinets or resealing with fresh desiccant and a humidity card.

Log bag open time on the reel or in the MES
Use dry cabinets at or below 10% RH for long holds
Bake only per J-STD-033 and the component label
Watch tape-and-reel limits on bake temperature

Common mistakes

Common failures are losing track of open time during line changeovers, assuming a part is safe because it looks fine, and baking at a temperature the carrier cannot take. Also check that peak reflow temperature does not exceed the label rating: a lead-free profile on a part rated for a lower peak causes popcorning even inside floor life. Defense and aerospace builds should keep these records with the lot for later traceability.

Frequently Asked Questions

What does MSL 3 mean?

MSL 3 means the package can stay outside its dry bag for up to 168 hours at 30 C and 60% relative humidity before reflow. After that time, the part needs a bake per J-STD-033 or must be returned to dry storage with its clock handled per the standard.

Does the floor life clock stop in a dry cabinet?

It depends on the cabinet and the standard's rules. J-STD-033 describes conditions under which exposure can be paused or reset by baking. Without a compliant cabinet or bake, treat the clock as still running.

What is MSL 6?

Level 6 parts must be baked before use and must be reflowed within the time on label, which is printed on the bag. They have no fixed floor life listed in the table because the label controls it.

Where do bake times come from?

From J-STD-033 tables, which depend on package body thickness, moisture level and bake temperature. They are not listed in this table. Use the standard or the component supplier's guidance for your exact part.

Netray can pull open-time and lot data from your ERP or MES into a private dashboard. We can show what that looks like on your own data.

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