1. Lead-Free Electronics Thermal Management of Electronics San José State University Mechanical Engineering Department

2. A Lead-Free Definition  Lead-free – the assembly of electrical and electronic packages without the intentional use of lead in the raw materials or the manufacturing process  NOTE: Lead may still exist in the final product even though it is not intentionally added

3. Lead-Free Standards  JEDEC – Solid-state devices that contain no more than 0.2% by weight of elemental lead  NEMI – Products that have no lead intentionally added and joints that have less than 0.2% lead by weight

4. Lead-Free Driving Mechanisms  Environmental Issues  Legislation  Ethics  Public Relations  Product differentiation

5. Environment Issues  Lead in electronics becomes an issue once deposited into landfills  Lead oxidizes when it comes into contact with water  This contaminated water that may seep into drink water supplies or out into the environment  Consumer electronics constitute 40% of the lead found in landfills

6. Legislation  Legislation has already been passed in Europe pertaining to a ban on lead in electronics. Effective July 1, 2006  Other countries (like US) may not have this ban but for their products to be marketed globally they must switch to lead-free  Lead-Free legislation may also come to other countries so it is beneficial for all electronics companies to begin the switch to lead-free prior to the enactment of these laws

7. Ethics and Public Relations  Knowing that lead is an identified toxin is it unethical to continue using it when alternatives exist?  The public knows that lead is a toxin therefore any effort by a company to produce lead-free products will enhance their stature with the public; this has been esp. important in Japan

8. Product Differentiation  Consumers are enticed by the difference between products  Lead-free is not necessarily an improvement performance wise but environmentally minded consumers will pay higher prices for lead-free electronics

9. Lead in Electronics  Most lead found in electronics is from lead base solders  Lead is used because:  It is abundant and readily available  It is cheap  It melts at reasonably low temperature so when soldering there is no damage to surrounding electronics; less thermal stress is induced than it would with other materials

10. Issues with lead-free solders  Finding relatively cheap alloys to use in place of lead  Higher reflow temperatures  Reliability and compatibility issues with lead-free components

11. Cost Issues  Most solders are lead-tin alloys but lead-free solders are usually some other alloy mixed with tin  The alternate alloy is more expensive but can be comparable in price to lead-tin solder for high- temperature electronics (above 200 degrees C)  Some alternate alloys include: silver, copper, pure tin, bismuth, antimony, ect  There are also cost issues associated with updating manufacturing processes

12. Possible Outcomes of Higher Reflow Temperatures  Increased hygrothermal expansion  Increased popcorning  Component and board warpage  Component and board delamination

13. Reliability and Compatibility Issues  Intermetallic formations between:  Component leads and boards  Lead-free solder and metallization on the chip, lead, or substrate  Formation of tin whiskers  Durability of:  Leaded and area array packages  Solder joints

14. Obsolescence Concerns  Will lead-based components be compatible with lead-free components?  If not, companies will begin to run out of replacement parts for lead-based assemblies once the switch to lead-free technology occurs

15. IBM Study  Experiment designed to test the life of ball grid arrays  Accelerated thermal cycling used for operating (0°C to 100°C) and extended ranges (-40°C to 125°C) were combine with various cycling up times to 240 minutes  Reflow temperatures for assemblies were 215°C for tin-lead solder and 235°C for tin- silver-copper and tin-silver bismuth alloys.

16. IBM Study Results  Both lead-free assemblies were more fatigue resistant in the operating range  Lead assemblies were more fatigue resistant in the extended range at higher cycling times  Reflow temperatures for lead-free solders were well below the expect 260°C

17. Nokia Study  Lead-free solder was used with nickel- gold printed circuit board finish, off-the- shelf components, ball grid arrays, chip scale packages, and leadless ceramic chips  Reflow temperatures for the leadless solder were achieved at 245°C

18. Nokia Study Results  Reflow temps. were below the expected 260°C  Moisture sensitive packaging showed more damage due to the higher reflow  Popcorn cracks were found  The components showed a failure rate five times that of the lead based solder  Board warpage was minimal  Lead-free joints out-performed lead based joints

19. Nortel’s Lead-Free PCB Assembly  Lead-copper solder was used with a reflow temp. of 242°C  Assembly was not really lead-free; a mixture of lead-based and lead-free components were used  Approximately ¾ of 200 boards were assembled on the first reflow and all boards passed electrical and functional tests  Demonstrated that components that are lead- based are compatible with lead-free assemblies

20. Expections of lead-based vs. lead-free assemblies  Most lead-free assemblies have initially proven to be as good or better than lead-based solders and are expected to uphold this equality. Research into prevention of popcorning must continue.  There are still reliability issues for long-term use including: intermetallic growth, creep deformation, and tin whiskers  There are still compatibility concerns with lead- base and lead-free assemblies but they should be mitigated as assemblies prove to be reliable