Practical guidelines for PWB Moisture Sensitivity, Packaging and Handling Mumtaz Y. Bora Peregrine Semiconductor San Diego, CA, USA
Agenda and Overview Industry Standards for Moisture Sensitivity Packages Package Handling/Baking/Packaging Guidelines PWB Handling/ Baking/Packaging Guidelines Controls at PWB/Assembly Site Summary
Moisture Classification Level and Floor Life Level Floor life (out of bag) at factory ambient <30 C/60% RH or as stated 1 Unlimited at <30 C/85% RH 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 labe
Handling PWB Moisture Sensitivity J-STD 020E -03/2008- IC Package MSL Class J-STD 033C 01/2007 Assembly MSL Floor Life J-STD 075 Non-IC Packages for Assembly IPC HDBK-001 -Baking Guidelines IPC TM 650 2.4.24.1 Time to Delamination IPC TM 650 2.3.40 Decomposition Temperature IPC SM 840D Solder Mask Qualification IPC 4101B -Laminate and Pre preg Materials J-STD-609 Marking and labeling of Components, PCBs and PCBAs to Identify Lead,Lead Free and other Attributes IPC 1601A Printed Board Handling and Storage guidelines- Contact :Joseph Kane BAE systems- IPC liaison- John Perry /Nancy Jaster
PWB Moisture Uptake Resin System Type of PWB construction Environment Temperature Humidity Rinse Operations Storage/Handling Moisture Sensitivity is not driven by Material alone Industry Guidelines for Maximum Moisture Content before packaging PWBs Test Method- TM 2.6.28 PWB Maximum Moisture Content Measurement
PWBs Used for Lead Free Reflow Mid Tg- 150C 310C Td High Tg -170C 340C Td Halogen Free Laminates -170C 340C Td Proposed Guidelines IPC- 1601Rev A Max Moisture 0.1% for Lead free Reflow (260C Max). Max Moisture - 0.2 % for Lead based Reflow (230C) Test Method IPC TM-650 Method 2.6.28
Typical Delamination Defects Delamination Blistering
PWB Supplier Quality Controls Storage/Handling Controls Prepreg Storage Laminate Storage Inner Layer Production Etched Cores Sub-Assembly Laminated Panels Evaluate/Audit : Transportation of Product Environment (Temp./Humidity) Warehouse Storage Conditions Baking Operation
Handling PWBs PWBs are Moisture Sensitive. Vacuum Sealed Bags should be opened just prior to usage. Open PWBs absorb moisture at room temp.
Supply Chain Controls Supplier Staging User Understand Parts Movement and Staging Customs Hold/ Warehouse Storage Request temp./ humidity controls Data Monitor seasonal temp. humidity changes Track Product Performance
Assembly Hub Temp./Humidity Temperature and Humidity Record Time Temperature 20+/-5 C Humidity 40-60% 8 20C 50% ab 12 19C 49% ab 16 20C 48% ab 20 19C 47% ab Initials
Warehouse Temp./Humidity Controls
PWB Baking Guidelines Baking is one option to remove excess moisture Baking can degrade solderability Impact cost and cycle time Oxidation of Surface Finish Cause Intermetallic Growth Process controls for Baking Humidity controls inside Oven Air/N2 Flow and Circulation Stack Height of PWBs Thermocouple Locations Time/Temp. Time Clock to start after oven has reached desired temp.
Baking Guidelines (contd.) Understand the Surface Finish Impact Lower temp. and longer bake times are effective Typically 105-125C for 4-6 Hours except OSP Bake PWB prior to packaging at PCB house Package in MBB bags with desiccant and Humidity Indicator Card OSP Max 105C for 2 hours or supplier guideline ENIG IPC 4552 ENEPIG IPC 4556 Immersion Silver IPC -4553 Immersion Tin IPC -4554 OSP No standards yet HASL IPC6012/6016
Final Packaging and Labeling MBB Bag Vacuum Seal Labeling HIC Card MBB Bag Label
PWB Packaging Specifications Proper MSL Packaging Desiccant Pack Packaging Document Audit Packaging Area Implement Bake Cycle
PWB Packaging Bake 120C -4 hours/package within 6 hours -25/pack Add desiccant and HIC card
Shelf Life and Baking Guidelines by Surface Finish Finish Type Shelf Life from Shipment date Baking Guidelines IPC Spec HASL 6 months 120C 8 HRS IPC 6012/6016 Immersion Gold- ENIG/ENEPIG OSP 6 months 6 months 120C 8 HRS Return to Supplier Remove OSP, Bake, Reapply OSP 4552/ 4556 N/A Selective Gold 6 months Return to Supplier Remove OSP, Bake, Reapply OSP IPC 6012/6016 Immersion Silver 6 months Return to Supplier Remove ImmAg, Bake, Reapply ImmAg IPC4553 Immersion Tin 6 months Return to Supplier Remove ImmAg, Bake, Reapply ImmTin IPC 4554
DPPM Monitoring Supplier A- DPPM Chart 2500 2000 2065. 1500 1000 500 0 841 783 754. 250 250 250 250 Q1-07 Q2-07 Q3-07 Q4-07
Lesson Learned Understand Supply Chain Clear Concise Documentation Effective Process Controls Training for MSL Handling OEM/Supplier/CM Partnership Respect the Material Limits
The End Thank-you for attending this training session. Contact Info mbora@psemi.com