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Representative Lead-Free Materials and Their Charcteristics
- Considering overall factors such as the mountability of each component (including that component's wettability, solderability and joint strength), ease of mass production, and cost, NEC Electronics has decided to use Sn-Bi plating for the lead exterior and Sn-Ag-Cu for the exterior solder dip and solder balls.
- Ni/Au plating will continue to be used for LGA as usual. Lead is not used in either of these plating material.
- Ni/Pd/Au plating and Matte Sn plating are used for some specific packages.
External solder plating
|
|
Sn-Pb
|
Sn-Bi
|
Sn-Cu
|
Sn-Ag
|
Sn-Zn
|
Ni/Pd/
Au
|
Matte Su
|
Ni/Au
|
Alloy
characteristics
|
Composition (wt%)
|
Pb: 10
|
Bi: 2.0
|
Cu: 1.5
|
Ag: 3.5
|
Zn: 9
|
—
|
Su: 100
|
—
|
Melting point
(°C)
Temperature from solid
phase to liquid phase
|
183 to 215
|
223 to 231
|
227 to 296
|
221
(eutectic)
|
198
(eutectic)
|
(soluble plating)
|
232
|
(soluble plating)
|
Mounting
characteristics
|
Wettability
|
|
|
|
|
|
|
|
|
|
Soldering temperature
|
|
|
|
|
|
|
|
|
|
Joint strength
|
|
|
|
|
|
|
|
|
|
Whisker
|
|
|
|
|
|
|
|
|
|
Suitability for mass production
|
|
|
|
|
|
|
|
|
|
Cost
|
|
|
|
|
|
|
|
|
|
Remarks
|
conventional
|
|
|
|
|
|
|
|
|
|
: Excellent,
|
: Good,
|
: Slightly inferior,
|
 : Inferior
|
|
External solder dip
|
|
Sn-Pb
|
Sn-Ag-Cu
|
Sn-Bi
|
Sn-Cu
|
Alloy
characteristics
|
Composition (wt%)
|
Pb: 37
|
Ag: 3
Cu: 0.5
|
Bi: 2.5
|
Cu: 0.7
|
Melting point (°C)
Temperature from solid
phase to liquid phase
|
183
(eutectic)
|
217 to 220
|
221 to 230
|
227
(eutectic)
|
Mounting
characteristics
|
Wettability
|
|
|
|
|
|
Soldering temperature
|
|
|
|
|
|
Joint strength
|
|
|
|
|
|
Suitability for mass production
|
|
|
|
|
|
Cost
|
|
|
|
|
|
Remarks
|
conventional
|
|
|
|
|
|
: Excellent,
|
: Good,
|
: Slightly inferior
|
|
Solder balls
|
|
Sn-Pb
|
Sn-Ag-Cu
|
Sn-Ag-Cu-Bi
|
Alloy
characteristics
|
Composition (wt%)
|
Pb: 37
|
Ag: 3
Cu: 0.5
|
Ag: 2
Cu: 0.75
Bi: 3
|
Melting point (°C)
Temperature from solid
phase to liquid phase
|
183
(eutectic)
|
217 to 220
|
210 to 216
|
Mounting
characteristics
|
Wettability
|
*1
|
*1
|
*1
|
|
Soldering temperature
|
|
|
|
|
Joint strength
|
|
|
|
|
Suitability for mass production
|
|
|
|
|
Cost
|
|
|
|
|
Remarks
|
conventional
|
|
|
|
|
: Excellent,
|
: Good,
|
: Slightly inferior
|
|
Note(*)
- Rate of spread of solder compared
