Lead-Free Questions and Answers
Lead-Free Questions & Answers
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Packaging | Lead-Free Status | Impact to Customers | Tin Whiskers
Green Compliance | Industry Consortia | Questions & Answers | Literature
- Are lead-free parts now available from National Semiconductor?
- How do I determine if a specific device is available as lead-free?
- When will National be transitioning to lead-free?
- How much notification will National’s customers have after a decision is made to convert to lead-free across the board?
- Do any of National's packages contain lead which is exempt from the RoHS requirement?
- Is there a price premium for lead-free products?
- Is there a change in part number for the lead-free components?
- How do I order lead-free parts?
- How will lead-free products be identified on the label?
- What other information is contained on the label?
- Does National have a web site for its lead-free program?
- Does National participate in any industry consortia related to lead-free transitioning?
- What is the lead-free composition and plating thickness?
- What are the measured values for the grain size and carbon content for the matte tin plating?
- What tests were included in the lead-free package-level qualification?
- Which lead-free reflow profile was used by National to qualify lead-free packages?
- How many reflow passes are allowed?
- What approach was used for board-level testing and what tests were run?
- Are the lead-free parts backward compatible with SnPb solder process?
- What information is available relating to tin whiskers?
- What is being done to mitigate whisker growth?
- Are the lead-free parts RoHS compliant?
- What are National’s plans for providing halogen-free (green) packages?
1. Are lead-free parts now available from National Semiconductor?
- Yes, most products are now available as lead-free upon request.
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2. How do I determine if a specific device is available as lead-free?
- Go to National external Web site (http://www.national.com) and perform a search on the device. If spec "NOPB" is displayed in the "Package Availability Table", then the indicated device is available as lead-free.
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3. When will National be transitioning to lead-free?
- The date of full conversion has not yet been decided upon and will be market-driven.
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4. How much notification will National’s customers have after a decision is made to convert to lead-free across the board?
- Once the decision is made to fully convert to lead-free, then a PDN will be issued. The customers will then have 12 months in which to place lifetime buys for SnPb products. An additional 3 months will be slated for final shipments of these SnPb products
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5. Do any of National's packages contain lead which is exempt from the RoHS requirement?
- High temperature solders with >85% lead are exempt from the RoHS lead prohibition requirement. Some of National's TO packages contain die attach solders which fall within this category. Products using this high lead die attach, but which are otherwise lead-free, are RoHS compliant.
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6. Is there a price premium for lead-free products?
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7. Is there a change in part number for the lead-free components?
- National's strategy is to maintain the same base part number and to include "NOPB" in the spec field to identify lead-free devices. For example, the lead-free version of the LM4890MMX would be identified as “LM4890MMX Spec NOPB” or “LM4890MMX NOPB”.
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8. How do I order lead-free parts?
- Please contact National Semiconductor's local franchised distributor or Customer Support Center and specify "lead-free" or "Spec. NoPb" at the time of your order. Additional information can be obtained from your National Semiconductor sales representative.
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9. How will lead-free products be identified on the label?
- The bar code label will state “PB-FREE” in human readable form. For example, refer to the following label affixed to the reel, where “PB-FREE” appears in the last line (prior to March 2006):
- Since March 2006 the label also shows RoHS compliance and lead finish category (see JESD97):
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10. What other information is contained on the label?
- The Moisture Sensitivity Level (MSL), the floor life (if MSL is not 1), and the peak body temperature. For example, the following lead-free part is MSL 3 with a floor life of 168 hours (after opening the drybag) and a peak body temperature of 260° C (prior to March 2006):
- Since March 2006 the label also shows RoHS compliance and lead finish category (see JESD97):
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11. Does National have a web site for its lead-free program?
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12. Does National participate in any industry consortia related to lead-free transitioning?
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13. What is the lead-free composition and plating thickness?
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14. What are the measured values for the grain size and carbon content for the matte tin plating?
| Base Metal |
Packages |
Average Grain
Size (microns) |
Average Carbon
Conc. (%) |
| C194 |
SOIC, SSOP, SOT, MDIP |
10.0 |
0.0355 |
| TAMAC2 |
TO-220, TO-263 |
9.3 |
0.0253 |
| C7025 |
PQFP, LQFP, TQFP, TSSOP |
7.5 |
0.0034 |
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15. What tests were included in the lead-free package-level qualification?
- The moisture sensitivity level (MSL) was reclassified at 260° C for all affected packages.
- Solderability tests were done on steam aged parts using lead-free solder per the requirements of J-STD-002B.
- The following reliability tests were run:
- Preconditioning + Autoclave (96 hours)
- Preconditioning + Temperature Cycle (-65/150° C for 1000 cycles)
- Preconditioning + Temperature Humidity Bias (85° C/85% RH for 1000 hours)
- High Temperature Storage Life (150° C for 1000 hours)
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16. Which lead-free reflow profile was used by National to qualify lead-free packages?
- For lead-free qualification National follows the IPC/JEDEC lead-free reflow profile as contained in J-STD-020C.
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17. How many reflow passes are allowed?
- Four (4) reflow passes are permitted based on current qualification requirements.
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18. What approach was used for board-level testing and what tests were run?
- A variety of surface mount packages were selected to cover small and large body sizes, gull-wing and J-bend lead geometries as well as land area contacts.
- Lead-free parts were attached to the PCB using both SnPb and Sn3.5Ag0.7Cu pastes.
- PCBs with both NiAu and Cu/OSP finishes were evaluated.
- Board-level temperature cycle was run at –40/125° C for 1050 cycles.
- Drop and vibration tests were run for the LLP package only.
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19. Are the lead-free parts backward compatible with SnPb solder process?
- National's lead-free leadframe-based surface mount packages are backward compatible. This means that leadframe-based components with matte tin finish can be attached to a PCB using tin/lead solder paste with a tin/lead solder profile (typical peak reflow temperatures ranging from 220° C to 235° C). This is not true for lead-free BGA or microSMD components, which are not compatible with the tin/lead solder process.
- National's lead-free LLP package has been shown to be backward compatible. It is recommended that the peak reflow temperature using tin/lead solder paste be 235 - 240° C, with time > 235° C of 10-30 seconds.
- Through-hole packages have not been evaluated for backward compatibility.
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20. What information is available relating to tin whiskers?
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21. What is being done to mitigate whisker growth?
- The leadframe is annealed within 24 hours after plating. The annealing is done for 1 hour at 150° C. This is the industry-accepted method for mitigating whisker growth.
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22. Are the lead-free parts RoHS compliant?
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23. What are National’s plans for providing halogen-free (green) packages?
- National has decided to convert all products for commercial (non-automotive) customers to halogen-free. As of May 2007, several quals have been completed and PCNs have been issued. The conversion will begin in June 2007.
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Packaging | Lead-Free Status | Impact to Customers | Tin Whiskers
Green Compliance | Industry Consortia | Questions & Answers | Literature
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