November 2022

MPS 5 Year Shelf Policy

Purpose: MPS stands behind its robust products. MPS is proud to announce that the product shelf life has been extended from 2 years to 5 years! MPS completed a reliability evaluation on different packages and the results support a 5 year shelf life. This assumes the integrity of the moisture barrier bag seal has not been compromised during that time period.

Product Evaluation: The evaluation performed determined the MPS products’ shelf life for products with lead (Pb)- free leads or termination finish. Steam conditioning (formerly known as steam aging) of the IC products, prior to solderability testing, is a common procedure used in the industry. Steam conditioning prior to solderability testing has proven to be a non-reproducible method for predicting solderability performance.

For this shelf-life evaluation, products were exposed to a controlled (Battelle Class2) environment both inside and outside of their normal packing materials, with known aging acceleration factors, and with a mechanism approximating that is seen in the real world.

The Shelf Life Evaluation Reliability Report is appended to this report

Questions & Answers

• What is Shelf Life? The minimum time that a dry-packed, surface mounted, moisture-sensitive device can be stored in an unopened moisture barrier bag (MBB) such that a specified interior bag ambient humidity is not exceeded.
• What is Floor Life?  The allowable time period between removals of moisture-sensitive devices from a moisture-barrier bag, dry storage, or dry bake and the soldering (surface mount) process.
• How is Shelf Life Measured?  The Shelf Life of a MPS product is based on the production date code.
• What are the required environmental conditions to ensure the 5 year Shelf Life? The integrity of the seal of the moisture barrier bag (MBB) shall not been compromised during the time period and product shall be stored in conditions of less than 40 °C and 90% relative humidity.
• How are MPS products packaged? MPS packs all surface mounted devices, regardless of Moisture Sensitivity Level (MSL), in a moisture barrier bag with desiccant and a Humidity Indicator Card (HIC).
• What standards does MPS follow?  IPC/JEDEC J-STD-033D: HANDLING, PACKING, SHIPPING AND USE OF MOISTURE, REFLOW, AND PROCESS SENSITIVE DEVICES
• Where can I find more information related to Floor Life, MSL, and baking parts? MPS has published the MSL Moisture Sensitivity Technical Note. This document is available for viewing and downloading at https://www.monolithicpower.com/en/support/quality/quality-documents.html

Please see our Standard Terms and Conditions for information about our product warranty.

Should you have any questions regarding this declaration, please contact your local Sales Representative.

1. Introduction

This evaluation determines the MPS products’ shelf life, the time that products can be stored prior to being soldered, with lead (Pb)-free finishes on their leads or terminations. Steam conditioning (formerly known as steam aging) of the IC products prior to solderability testing is a common procedure used in the industry. Steam conditioning prior to solderability testing has proven to be a nonreproducible method for predicting solderability performance.

For the shelf-life evaluation documented in this report, products were exposed to a controlled (Battelle Class2) environment both in and outside of their normal packing materials, with known aging acceleration factors, and with a mechanism approximating that seen in the real world.

2. References Document

2.1                  Standard Practice for Conducting Mixed Flowing Gas (MFG) Environmental Tests, ASTM B827−92.

2.2                  Solderability Tests for Components Leads, Terminations, Lugs, Terminals and Wires, IPC/EIA/JEDEC J-STD-002.

2.3                  Requirements for Soldered Electrical and Electronic Assemblies, IPC J-STD-001.

3. Evaluation Procedure

Battelle Class2 MFG (Mixed Flowing Gas) environment was selected for this shelf life evaluation, which test has been well characterized by previous work and represents a slightly corrosive indoor atmosphere where the gas concentrations and humidity levels result in corrosion of plated copper (Cu) materials, but not copper creep corrosion. Class2 environments generally are described as indoor environments having no humidity control, such as that typically found in a warehouse.

Table1 shows the test condition in this evaluation and are described in detail in ASTM B827– 92.

Figure1 shows schematic horizontal recirculating MFG test System.

Flow1 shows the detailed steps of this evaluation.

Table 1: Battelle Class 2 MFG Test Condition

Figure1. Schematic Horizontal Recirculating Mixed Flowing Gas (MFG) Test System

Flow1. Shelf Life Evaluation Steps

4. Summary of Evaluated Results

4.1 Visual-Inspection

After 96hours exposure in MFG environment, 3pcs samples of each package with different packing types were visual inspected with 50×magnification, no visible corrosion on samples’ lead surface.

4.2  Solderability

After 96hours exposure in MFG environment, check test samples’ solderability per surface- mount process simulation test method as “IPC/EIA/JEDEC J−STD−002, test method S”, which has been shown that this method is more appropriate for surface-mount devices than the traditional dip-and-look solderability method. The pass criteria is “All leads shall exhibit a continuous solder coating free from defects for a minimum of 95% of the critical area of any individual lead” in J-STD-002. No failure on any test samples.

4.3 Wetting-Balance

After 96hours exposure in MFG environment, check 2leaded packages’ soldering performance per wetting balance test as “IPC/EIA/JEDEC J−STD−002, test method E”. There shows the time-to-cross-zero (T0) axis in seconds. The units, exposed to the MFG conditions while in normal packing materials, are with very short (good) wetting times, that all they are <2s.

4.4 Board Mount

Units with 96hours exposure from each group were soldered to PCB with standard SMT process by a commercially available Pb-free alloy with composition of 96.5%Sn /3%Ag /0.5%Cu, to judge the solder joint.

4.4.1  Visual Appearance of Solder Joints

All groups exhibited good solder wetting. For all groups (except group5, LGA solder mount wasn’t exposed, can’t visual check), tested units exhibited good solder wetting performance after 96hours exposure, regardless of whether the units were stored loose or in tape. The visual appearance of all solder joints pass that judged basing on criteria in J-STD-001.

4.4.2  Cross Sections of Solder Joints

All groups exhibited good solder wetting. For all groups, tested units exhibited good solder wetting performance after 96hours exposure by cross sections check, regardless of whether the units were stored loose or in tape. The cross sections of all solder joints pass that judged basing on criteria in J-STD-001.

5. Long Term Storage Evaluation

Pick 6 lots with >5 years in storage warehouses to do evaluation.

5.1 Packaging Materials Evaluation

5.2 Tape Peel Strength Evaluation and ESD Testing

5.2 Solderability Evaluation

6. Summary of Results

• The 6 groups samples, on behalf of MPS Pb-free-finished ICs from different package type, all can pass solderability testing, still keep the good soldering performance, after 96 hours exposure to the Class 2 condition, it guarantee the storage shelf life more than 8 years.
• >5 years warehouse storage samples passed the material/solderability evaluation.

7. Conclusion

The product shelf life is longer than 5 years.