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| Lead-Free
Status |
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The major project
to fulfil the RoHS Directive was the conversion of the SnPb
(85/15) plating to the Pb-free version.
From the technical solutions available, we selected the pure
matt tin plating, with a minimum thickness of 7 µm and annealing
of 1 hour @ 175ºC within 24 hours after plating, because the
coating is done over bare copper. This solution applies for
the internal plating process and for those of our subcontractors.
The qualification of this process change was done in 2005 according
the following procedure and criteria: |
| > Preconditioning
in Surface Mounted Devices SMD at Moisture Sensitivity Level
MSL=1, according to JEDEC standard JSTD - 020C. |
| > Whisker testing,
according to NEMI recommendations which were included subsequently
in JESD22A121 standard (May 2005) and updated in JESD201 (March
2006). |
| |
| Test |
Test Description |
Test Conditions |
# Lots
|
#Units
|
#Fail
|
| Visual Inspection |
Microscope X50 magnification |
As per solder plating
criteria |
3
|
150
|
0
|
| Plating Thickness |
XRF (Fischercope) |
7-20 µm |
3
|
30
|
0
|
| Solderability |
After Plating
After Preconditioning:
PCT 105ºC, 16H
After Preconditioning:
155ºC, 16H |
245ºC,
3sec.
Solder SnAg3Cu0.5 & Solder Sn63/Pb37
Acceptance criteria 95% |
3
|
90
|
0
|
|
3
|
90
|
0
|
|
3
|
90
|
0
|
| Resistance to Solder Heat |
Wave
Bath
Iron Solder
|
260ºC, 10 sec.
260ºC, 10 sec.
350ºC, 3.5 sec. |
|
90
90
90
|
0
0
0
|
| Whisker
Growth After |
Room Temperature Storage |
25ºC, 30-80% RH, 5000H,
SEM 3000X magnification
Whisker length: < 40 m |
3
|
90
|
0
|
| Thermal
cycles |
-40ºC
+150ºC, 2000 cycles
SEM 3000X magnification
Whisker length: < 45 m |
3
|
90
|
0
|
| High
Humidity Storage |
85ºC,
85%R.H., 5000H
SEM 3000X magnification
Whisker length: < 40 m |
3
|
90
|
0
|
|
| Lead-free plated components
are compatible with lead soldering conditions. |
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