Moisture Sensitivity Level Explained: MSL, Dry Pack, HIC, and Floor Life
MSL is the package's qualified exposure class before reflow. Dry pack protects the devices, the humidity indicator card reports the bag environment, and floor life is the cumulative permitted out-of-bag exposure. They are four different controls. A good-looking HIC does not prove every device is dry, and a new seal date does not restore hours already used.
At no more than 30°C / 60% RH under the standard reference table.
MBB, desiccant, HIC, caution label, carrier, seal, and traceable records.
Use the printed instructions for that card, not a universal color slogan.
Keep the used hours with the lot unless an approved recovery process resets them.
Manage three records, not one label.
A release decision needs the exact package classification and peak reflow temperature, the dry-pack/HIC condition at receipt and opening, and a cumulative exposure history. If one record is missing, another cannot safely substitute for it.
Exact OCM part/package, MSL, peak package-body temperature, and applicable customer or standards revision.
MBB integrity, seal date, desiccant, HIC result, caution label, carrier condition, and repack history.
Every ambient interval, dry-cabinet interval, reseal, bake, split, line issue, return, and final disposition.
The terms work together, but they answer different questions.
The practical mistake is letting one acceptable observation erase a different unknown. A valid MSL label does not reconstruct handling; an HIC does not calculate hours; a reseal does not dry a package by itself.
| Term | What it answers | What it does not prove | Buyer or factory action |
|---|---|---|---|
| Moisture sensitivity level | How long the exact qualified package may remain exposed under specified conditions before the relevant reflow process. | The actual moisture content of this reel, whether the bag stayed intact, or whether handling was compliant. | Verify the complete OCM part number, package, MSL, and peak package-body classification temperature. |
| Dry pack | How moisture-sensitive devices are protected during shipment and sealed storage. | That an opened, damaged, sampled, repacked, or incorrectly resealed lot still has its original condition. | Inspect the complete packaging system and request repack, opening, storage, and bake disclosure. |
| Humidity indicator card | Whether the environment around the card reached the thresholds printed on that card. | The precise moisture in each package body, a complete exposure history, or a full unused floor-life allowance. | Read immediately, apply the exact printed rule, record the result, and resolve conflicting evidence. |
| Floor life | The permitted cumulative exposure after opening or leaving qualified dry control and before reflow. | Sealed shelf life, solderability life, electrical life, date-code acceptability, or authenticity. | Timestamp every interval and transfer the remaining value with each reel, tray, tube, split, or kit. |
| Bake | An approved time-and-temperature drying process that may restore handling status. | Repair of cracks, delamination, corrosion, oxidation, damaged carriers, mixed lots, or lost traceability. | Use the controlled table and OCM instruction; verify package, thickness, carrier, cycle, and solderability limits. |
Moisture can remain invisible until rapid heating turns it into a package-integrity problem.
Plastic encapsulants, die-attach materials, organic substrates, and interfaces can absorb moisture from ambient air. The device may look normal and pass room-temperature electrical checks. Reflow then adds rapid heat, vapor pressure, material expansion, and interface stress.
Diffusion
Moisture moves into nonhermetic polymeric package materials during humid exposure. Uptake depends on material, geometry, temperature, RH, and time.
Rapid heating
Reflow can push the package above 200°C within minutes. Oven setpoint is not the same as measured package-body temperature.
Internal stress
Vapor pressure, hygroscopic swelling, thermal expansion mismatch, and weakened adhesion load interfaces inside the package.
Visible or latent damage
Cracks, bulging, die-attach separation, or delamination may occur. Some defects require scanning acoustic microscopy and may escape initial electrical test.
Its package-assembly guidance documents a typical crack after solder shock and warns that the crack can create a direct path from leadframe to the external environment.
TI's SNOA300A includes a measured moisture-absorption profile for a 28 × 28 × 3.4 mm QFP and explains dry packing, HIC evaluation, floor life, and resealing.
An audible “pop” is not required. Internal delamination can be present while the exterior looks acceptable.
Public records show how real organizations test, specify, and control moisture-sensitive devices.
These are manufacturer, NASA/CALCE, and JPL records. They are not YURUNOX customer results, and they should not be converted into a universal bake recipe.
Infineon shows the physical defect and the carrier tradeoff.
Infineon's assembly guidance reproduces the standard MSL floor-life table, shows a typical “popcorn” crack after solder shock, and states that repeated baking can harm solderability through oxidation or intermetallic growth. It also warns that trays, tubes, reels, and tapes may not withstand elevated bake temperatures.
Electrical passing did not eliminate the need for package-integrity inspection.
A NASA-hosted CALCE guidebook lists eight plastic-encapsulated device types. The protocol baked parts at 125°C for 24 hours, soaked them to each manufacturer's JEDEC MSL condition, applied flux, reflowed, inspected externally at 40×, and used scanning acoustic microscopy for delamination. All parts passed electrical testing after preconditioning.
JPL's QC115a makes the dry-pack system explicit.
JPL's public quality clause QC115a requires moisture-sensitive plastic SMDs above MSL 1 to be dry packed with a moisture-barrier bag, desiccant, humidity indicator, identification label, and caution label, under the latest required J-STD-033 handling framework.
MSL 1 through 6: use the table as a classification reference, not a release decision.
The exact lot label, OCM data, customer specification, actual factory environment, and licensed procedure still control.
| MSL | Reference floor life | Reference condition | Operational meaning |
|---|---|---|---|
| 1 | Unlimited | ≤30°C / 85% RH | No standard floor-life time limit at or below the stated condition. ESD, contamination, solderability, storage, carrier, traceability, and process controls still apply. |
| 2 | 1 year | ≤30°C / 60% RH | A long allowance, but still an exposure classification rather than sealed shelf life. |
| 2a | 4 weeks | ≤30°C / 60% RH | An intermediate class that can be lost when ERP or label systems accept only whole numbers. |
| 3 | 168 hours | ≤30°C / 60% RH | Seven cumulative reference-condition days. Common enough to deserve automatic kitting and return controls. |
| 4 | 72 hours | ≤30°C / 60% RH | Three cumulative days, including inspection, setup, stoppage, holds, and line-side time. |
| 5 | 48 hours | ≤30°C / 60% RH | Two cumulative days. Small scheduling delays can materially change disposition. |
| 5a | 24 hours | ≤30°C / 60% RH | One cumulative day. Partial issues and rapid dry return need disciplined timestamps. |
| 6 | Time on label | ≤30°C / 60% RH | Mandatory bake before use, then reflow within the time stated on the caution label. |
Manufacturer guidance from Infineon reproduces these commonly used values and ties moisture sensitivity to the maximum allowed reflow temperature. MSL is assigned to the exact qualified device/package construction, not to a broad package name such as QFN, BGA, LED, or sensor.
Inspect the system, not the metallic appearance or vacuum tightness.
A proper dry pack normally combines the correct moisture-barrier bag, dry desiccant, HIC, caution/identification label, approved component carrier, qualified seal, and traceable handling records.
Moisture-barrier bag
Correct material, intact surface and seams, no puncture, tear, open seal, or contamination.
Desiccant
Present in the approved amount, dry, suitable for the pack process, and not leaking or damaged.
HIC
Present, readable, appropriately stored, and interpreted immediately under its printed rule.
Caution label
Exact MSL, seal date, floor life, peak temperature, and handling instructions remain legible.
Carrier and records
Reel, tray, tube, tape, quantity, lot/date code, opening, reseal, exposure, and bake status agree.
Read the card before room air changes the evidence.
Card chemistry, spot values, color direction, reversibility, storage limits, and acceptance criteria can differ. A universal “blue is dry, pink is wet” rule is not safe across suppliers.
Confirm the lot and ready the exposure log before opening.
Check the unopened MBB, seal, labels, punctures, tears, and contamination.
Use the approved area and record the exact opening time immediately.
Compare the relevant spots with the printed card and caution-label rule.
Capture result, time, lot, MSL, operator, ambient condition, and anomaly.
Move to SMT, qualified dry control, approved reseal, or quarantine.
What an acceptable HIC supports
- The card did not indicate excessive humidity under its printed criteria at the time it was read.
- The observation can be combined with bag, label, seal, and handling records.
- The receiving team has one objective part of the dry-pack evidence.
What it cannot prove
- That every package body is dry or undamaged.
- That the MBB was never punctured or mishandled.
- That the reel has a fresh, full floor-life allowance.
- That another supplier's HIC uses the same interpretation.
Resealing between runs does not erase the hours already used.
Use this simple planner only when every interval was within the applicable reference conditions and no unknown or out-of-limit event occurred.
Reference-condition planner
Add up to three ambient-exposure intervals for one lot.
The clock includes more than productive machine time
Count receiving inspection, sampling, kitting, feeder setup, line-side waiting, breakdowns, quality holds, unfinished work orders, and time before the leftover reel returns to qualified dry control.
Dry storage may pause or recover under defined conditions
A cabinet display is not enough. Validate usable volume, RH mapping, door-open recovery, alarms, calibration, access, excursions, and lot entry/exit history. Moderate dry storage may stop additional accumulation without restoring the original allowance.
Shelf life is different
Shelf life concerns correctly sealed material under specified packaging and storage. Floor life concerns exposure after opening or removal from qualified dry control. An unexpired sealed-shelf-life label does not give an opened reel fresh hours.
Vacuum appearance is different
A tight bag can still contain the wrong desiccant, a damaged card, an inadequate barrier, or an unrecorded opening. A qualified seal protects future storage; it does not reconstruct the past.
Start with the evidence state, then choose the controlled route.
The panel below is a planning guide. The licensed current standard, exact OCM instruction, customer specification, and internal quality procedure remain authoritative.
Verify identity and pack condition before breaking the seal.
Match PO, packing list, OCM label, MSL caution label, part number, quantity, lot/date code, seal date, and carrier. Prepare the exposure log first. Open only in the approved area, read the HIC immediately, and route the material without delay.
Carry used hours with the lot through every split and return.
Subtract documented qualified ambient exposure from the applicable allowance. If the material will not complete reflow, move it to the validated dry-storage or approved reseal route without deleting the used hours.
One acceptable cue cannot cancel a puncture, missing card, or unknown seal history.
Record the anomaly, isolate the material, preserve labels and packaging, review source and transport records, and obtain the controlled quality/process-engineering disposition. Do not recreate a pass from vacuum appearance or urgency.
Bake only under the correct package, exposure, carrier, and solderability limits.
Identify body thickness, MSL, classification temperature, prior exposure, carrier rating, labels, termination finish, cumulative bake history, and the reason for drying. Use the controlled table and OCM instruction. Record oven, recipe, actual time/temperature, operator, cooling, post-bake pack, and new clock status.
Build the clock into the material flow instead of reconstructing it after a line stop.
Require exact MSL, peak temperature, original/repack status, dry-pack method, and handling records.
Match identity, inspect the unopened MBB and carrier, quarantine damage, and plan the HIC read.
Issue the smallest practical quantity and transfer lot identity plus remaining life to every split.
Record release from dry control, work order, feeder, ambient condition, and all setup or hold time.
Verify the actual package-body profile and complete the relevant reflow inside the allowed window.
Timestamp removal from ambient, calculate cumulative use, inspect the carrier, and enter the approved dry route.
Keep the rule tied to the exact material.
OCM part/package, lot/date code, quantity, MSL, classification temperature, supplier/source, bag seal/open time, carrier, and work order/board lot.
Record intervals, not only a final number.
Ambient start/end, temperature/RH when required, cabinet ID and entry/exit, RH trend, reseal, bake, operator, equipment, and exception intervals.
Give the next user an actionable status.
Nominal remaining hours, calculation basis, qualified-condition limitation, hold/release status, approved procedure, disposition owner, and linked evidence.
Ask for moisture evidence before shipment, especially for partial reels and broker stock.
A genuine device can still be unsuitable for reflow when dry-pack integrity, exposure history, carrier condition, or storage evidence is poor.
Moisture-sensitive component requirement 1. Supply the exact approved OCM part number and package. State the OCM-defined MSL and peak package-body classification temperature. 2. Disclose whether the lot is in original factory dry pack, authorized-distributor dry pack, or later repack. No source, lot, package, carrier, or pack substitution without written approval. 3. Provide the MBB seal date, label photos, HIC type/status, desiccant, carrier condition, lot/date code, quantity, and applicable storage basis before shipment. 4. Disclose every opening, sampling, inspection, test, split, dry-cabinet interval, reseal, and bake. Include cumulative ambient exposure and remaining floor life for each lot or split. 5. If baked, provide the approved procedure/table, package and carrier basis, equipment, actual time/temperature record, operator, cooling, post-bake pack, and new handling status. 6. Material remains subject to incoming identity, MBB, HIC, carrier, traceability, exposure-record, and risk-based technical acceptance. Define rejection, return, and corrective-action terms.
Three common failure patterns show where the record chain breaks.
The MSL 3 reel “reset” by a new seal date
A reel is opened Monday, used on two shifts, and resealed Friday with desiccant. The old exposure log is not transferred, so the next work order assumes a fresh 168 hours. The new seal protects future storage but cannot prove the absorbed moisture was removed or the used hours were zero.
Controlled response: quarantine, reconstruct every documented interval, or apply the approved unknown-history disposition.An acceptable-looking HIC inside a punctured MBB
Receiving finds a puncture near the bag edge while the card appears acceptable. The evidence conflicts: the card cannot show how long the puncture existed, the local path to the carrier, or whether it was read and stored correctly.
Controlled response: preserve the pack, record both observations, review transport/seal history, and escalate under the lot's MSL and current procedure.An urgent high-temperature bake in a plastic reel
A line-down lot exceeds floor life and enters a hot oven before anyone checks the reel or cover-tape rating. Drying the package may reduce one risk while warping the carrier, weakening tape, disturbing orientation, or creating feeding and contamination problems.
Controlled response: select the approved recipe first, verify the media, and use controlled transfer or lower-temperature alternatives only when permitted.Send the MPN, MSL label, pack photos, and handling history before purchase.
YURUNOX can help organize a lot-specific sourcing and evidence review around the exact package, quantity, source situation, dry-pack condition, exposure history, and required delivery date. Final release remains subject to the buyer's approved engineering and quality requirements.
- Exact OCM part number and package
- MSL label and peak temperature
- MBB, HIC, desiccant, and carrier photos
- Original pack, repack, open, reseal, and bake history
- Quantity, destination, and delivery date
Connect moisture control to supplier, quality, and receiving decisions.
MSL, HIC, floor life, storage, and bake questions
Use the exact component label, current controlled procedure, OCM package information, and customer requirement for the final lot decision.
What does moisture sensitivity level mean?
MSL classifies a nonhermetic surface-mount package by how long it may remain exposed to specified ambient conditions before the relevant solder-reflow process. It supports dry packing, storage, floor-life tracking, and drying controls. It does not measure the actual moisture in one device.
What is the reference floor life of MSL 3 components?
The commonly published reference is 168 cumulative hours at no more than 30°C and 60% RH. Verify the exact OCM label and peak classification temperature, and apply controlled equivalent-exposure or disposition rules when conditions or history fall outside the qualified basis.
Does MSL 1 mean no moisture or storage control is needed?
No. MSL 1 has unlimited floor life only at or below its stated 30°C / 85% RH reference condition. ESD, contamination, solderability, packaging, storage, carrier, reflow profile, traceability, and manufacturer-specific rules still apply.
What is the difference between shelf life and floor life?
Shelf life is the storage period for correctly sealed material under specified packaging and environment. Floor life is the permitted cumulative exposure after opening or leaving qualified dry control and before reflow. A valid sealed-shelf-life label does not reset an opened reel.
How should I read a humidity indicator card?
Read it immediately after opening and follow the interpretation printed on that exact card and caution label. Record the result with the lot and opening time. Do not use a universal color rule or treat the HIC as a calibrated moisture meter for the components.
Does a good HIC result prove the components are dry?
No. It supports the limited conclusion that the card did not indicate excessive humidity under its printed criteria when read. It does not prove every package body's moisture, prior exposure accounting, seal integrity, or a full remaining floor life.
Does vacuum resealing reset MSL floor life?
No. A qualified reseal can protect against additional uptake, but vacuum appearance or a new seal date does not remove absorbed moisture or restore consumed hours. Keep cumulative exposure with the lot. A reset requires the approved recovery or drying method.
When should moisture-sensitive components be baked?
Bake when the applicable standard, OCM instruction, customer rule, or approved engineering disposition requires it—for example after excessive or unknown exposure, an unacceptable HIC, compromised dry pack, or an MSL 6 instruction. Do not bake simply because the date code is old.
Can I bake components in their original reel or tray?
Only if the carrier is rated for the selected temperature and the controlled procedure permits it. Many shipping reels, tubes, trays, tapes, and labels are not high-temperature media. An uncontrolled carrier transfer can also introduce ESD, orientation, lead, cleanliness, count, and traceability risks.
What should I do when floor-life history is unknown?
Quarantine the material and reconstruct documented ambient, cabinet, reseal, bake, inspection, test, and line-use events. If the history cannot be established, use the approved unknown-exposure disposition rather than entering zero hours. Link the decision to affected assemblies.
Primary sources used for the technical and standards review
- Global Electronics Association — IPC Standards Revision Table
Current revision history for J-STD-020 and J-STD-033. - Global Electronics Association — Status of Standardization
Current published, final-draft, and project-approved status. - IPC/JEDEC J-STD-033D table of contents
Official handling-standard overview. Obtain the licensed standard for requirements and tables. - Infineon — General Recommendations for Assembly of Packages
MSL table, reflow damage, dry handling, and baking cautions. - Texas Instruments SNOA300A — Plastic Package Moisture-Induced Cracking
Moisture absorption, dry packing, HIC, floor life, and resealing. - Texas Instruments — Quality and Reliability FAQs
Manufacturer-specific shelf-life, MBB, HIC, storage, and baking guidance. - Microchip — Moisture Sensitivity Levels Communication
Package-specific MSL, labels, seal dates, floor life, and shipping-media limits. - NASA NEPP / CALCE — Guidebook on the Use of PEMs
Named-device preconditioning, reflow, electrical test, microscopy, and SAM workflow. - NASA JPL — Quality Clause QC115a
Operational dry-pack requirements for moisture-sensitive plastic SMDs. - NXP AN1902 — Package and MSL Guidance
Package-specific lookup, MSL definitions, floor-life table, and carrier-temperature caution.
This article is an educational purchasing and handling guide, not a replacement for a licensed standard, original component manufacturer instruction, customer specification, or factory engineering disposition. External images remain hosted by their source platforms and are attributed under the licenses stated in each caption.