MSL Baking Time Calculator
(J-STD-033)
Calculate, interpret and document the baking process according to technical standards and EPS Global’s expertise.
Frequently asked questions
Integrated circuits (ICs) and other encapsulated devices used in the electronics industry exhibit hygroscopic characteristics, meaning they tend to absorb moisture from the environment when exposed outside of sealed, humidity-controlled packaging. This absorption occurs gradually and, in most cases, is not visually perceptible.Although the presence of moisture in small quantities may seem irrelevant at first glance, it represents a significant risk during the electronic assembly process, especially during the reflow stage in the manufacture of printed circuit board assemblies (PCBAs).
This risk is substantially amplified by prevailing climatic conditions in humid regions. Areas such as Manaus, Brazil, for example, have an average annual relative humidity of around 80%, with daily variations frequently ranging between 79% and 87% due to the humid equatorial climate. Similar conditions are also observed in industrial centers worldwide where ambient humidity frequently exceeds the levels considered ideal for handling sensitive components.
Before even evaluating any impact on the functional performance of the device in the final product, it is essential to understand the critical effects of absorbed moisture during the reflow process. When a component containing internal moisture is subjected to the high thermal profiles of reflow, this moisture can rapidly vaporize, generating significant internal pressures in the encapsulation. This phenomenon can result in mechanical damage, such as cracks, internal delamination, or the “popcorning” effect, definitively compromising the reliability of the component and the assembly.
In this context, controlled baking is established as an essential preventive step, whose purpose is to remove absorbed moisture before assembly, mitigating the risks of immediate and latent failures and ensuring the integrity of the production process and the final product.
Encapsulated electronic components exhibit different levels of sensitivity to humidity, classified according to the Moisture Sensitivity Level (MSL). Each MSL level defines the maximum permitted exposure time to ambient humidity (Floor Life) after opening the sealed packaging, considering typical factory conditions (≤ 30°C / 60% RH).
The following table shows the relationship between the MSL level and the respective permitted exposure time, serving as a reference for deciding whether immediate baking or mounting is necessary before the reflow process.
| MSL | Floor Life (out of bag) |
|---|---|
| 1 | Unlimited |
| 2 | 1 year |
| 2a | 4 weeks |
| 3 | 168 hours |
| 4 | 72 hours |
| 5 | 48 hours |
| 5a | 24 hours |
| 6 | Mandatory bake before use. After bake, must be reflowed within the time limit specified on the label |
Improper execution of the baking process on electronic components or other hygroscopic materials can result in permanent damage to the device or, in more critical scenarios, the generation of latent faults that are not detectable during visual inspections or initial electrical tests, manifesting themselves only after the product enters operation in the field.
Among the main risks associated with incorrect baking are:
- Thermal degradation of the encapsulation, compromising the mechanical integrity of the component
- Internal delamination or microcracks, which significantly reduce reliability throughout the product’s lifecycle
- Compromised internal interfaces, with a direct impact on electrical and thermal performance
Additionally, special attention should be paid to the thermal restrictions associated with the packaging of the components. Devices packaged in tape and reel have specific temperature limitations, since the polymeric elements of the packaging system—including the plastic reel, carrier tape, and cover tape—can soften, deform, or suffer irreversible damage when subjected to high temperatures.
As an engineering practice, it is recommended that tape and reel components not be subjected to temperatures exceeding 60°C, unless explicitly authorized by the manufacturer. This condition should always be verified in the component datasheet and/or material labels, ensuring compliance with supplier specifications and mitigating risks of process and final product failures.
As the assembled components are preheated before the reflow process, the temperature increases at a rate of approximately 2°C per second. Soak and reflow temperatures occur around 220°C (430°F), with a maximum temperature between 240–250°C (460–480°F) being reached for periods between 40 and 80 seconds.
During this process, any moisture contained in a component will rapidly convert to vapor and can literally cause the component to rupture. Sometimes the damage is visible as cracks and broken packages, but in some cases, X-ray inspection is necessary to identify component damage, as it is not always obvious and may be located in the die or other internal parts.
This effect is often called “popcorning,” and it is not always detectable during the assembly process.
To prevent popcorning during the reflow process, components need to be baked in a controlled environment to allow moisture to evaporate at a slow, safe, and consistent rate—this is the baking secret that many overlook.
At EPS, we have specially designed, software-controlled ovens with multiple functions, from controlling the temperature and time components are exposed to heat, to specialized requirements for delicate and difficult-to-handle components where the temperature needs to be increased in increments during the baking process. This ensures your components are never stressed. Components are returned to you in your preferred packaging (e.g., on tape and reel or in trays), properly dry-bagged with humidity indicator cards and desiccant.
Important: If you choose to perform this service independently, remember that the safe temperature limit for baking components on reels is 40°C, and you should avoid stacking reels as this can cause plastic deformation in the reel flanges.
At EPS, using our automated handlers, we can de-reel your devices and place them in trays before the baking process at higher temperatures (+90°C), and then, after completion, tape and reel them again. This allows us to perform the service faster and ensure that the material returns to your facility on time.
Component manufacturers often prefer to ship components on reels, allowing customers to receive parts in the simplest and most efficient format for assembly. However, for larger connectors or modules requiring protection, trays are sometimes favored for their robustness during long-distance shipping and better mechanical protection. Their square shape can also make them more efficient for air freight.
This is a challenge that EPS solves by offering tape and reel packaging for any component (mechanical, electronic, plastic, etc.) larger than 3mm. This allows baking to be performed in trays (allowing for higher temperatures and faster processing) and then packaging on reels to facilitate assembly in pick-and-place machines.
Yes, but first you need to know that humidity is undoubtedly one of the biggest enemies of semiconductors. Semiconductors are composed of elements like silicon or germanium, which are extremely hygroscopic, meaning they easily absorb moisture from the air. Each semiconductor will have a Moisture Sensitivity Level (MSL).
MSL is an electronic standard for the length of time a moisture-sensitive device can be exposed to environmental conditions (30°C/85% RH at Level 1; 30°C/60% RH at all other levels). This determines the semiconductor’s floor life, i.e., how long it can remain exposed after opening before use. So, considering this, can we reset the floor life of a semiconductor?
If we take international standards, such as the Joint Industry Standard (IPC/JEDEC J-STD-033D), as a guideline, then not only is it possible, but the procedures are clearly defined. Any moisture-sensitive electrical component can undergo a baking process to remove moisture and, when done correctly, can reset its exposure time and floor life. This means that all semiconductors can be “revived” for use in the assembly of electronic products.
The Joint Industry Standard Document (IPC/JEDEC J-STD-033D) specifies the requirements and procedures to be considered for baking components, such as:
- MSL of the component
- Previous exposure time, if available
- Thickness of the package
- Temperature of the baking oven
- Oven specifications regarding humidity control
- Plastic, paper, and labels
- ESD protection
- Risk of oxidation
The IPC/JEDEC J-STD-033 standard does not explicitly prohibit performing multiple baking cycles on the same component. However, each additional cycle represents cumulative thermal exposure, which can negatively impact the mechanical integrity and reliability of the package.
Although baking is effective at removing absorbed moisture, excessive baking can:
- Induce cumulative thermal stress
- Increase the risk of internal delamination
- Affect the physical properties of the encapsulation and internal interfaces
Whenever multiple baking cycles are considered:
- Assess the actual need for reprocessing
- Prioritize proper floor life control
- Consult the component manufacturer for specific limits
Shelf Life: Refers to the maximum storage period of a component within the sealed packaging (moisture barrier bag or MBB), containing desiccant and humidity indicator card (HIC), under controlled conditions.
Floor Life: Corresponds to the maximum permitted exposure time of the component outside the MBB, in a factory environment, before assembly or the need for baking.
A component may be within its shelf life but have already exceeded its floor life after the packaging is opened. Effective process control requires independent monitoring of shelf life and floor life, and accurate recording of exposure time after opening the packaging.
Different baking temperatures represent distinct moisture removal strategies, with direct impacts on processing time and packaging limitations.
- 40°C: Slower process, but compatible with sensitive packaging, such as components on tape and reel
- 90°C: A balance between time and thermal risk, widely used for tray or tube components
- 125°C: Rapid moisture removal, but with strict packaging restrictions and greater thermal stress
Temperature selection should take these and other variables of your process into account:
- Packaging type
- Thermal limits of the material
- Urgency of the production process
After baking, the component returns to a low internal moisture condition, but remains susceptible to moisture reabsorption if not stored properly.
After the baking process, it is recommended to:
- Repackage the components in a new moisture barrier bag (MBB)
- Use fresh desiccant
- Insert new humidity indicator card (HIC)
- Reset floor life control
Improper storage after baking negates the effect of the process and may require reprocessing. You can purchase all moisture-sensitive packaging materials through EPS.
Baking is an effective corrective measure for removing absorbed moisture; however, it does not completely eliminate all risks associated with reflow soldering.
Even after baking, failures can occur due to:
- Inadequate reflow profiles
- Pre-existing damage to the package
- Incorrect handling or prolonged exposure post-baking
- Other correlated industrial process failures
Baking should be viewed as part of a set of best practices, which includes environmental control, proper packaging, and well-defined thermal processes. If you have questions or are looking to improve your manufacturing process, we recommend learning more about our comprehensive component services.
