| In order to evaluate the tin whisker growth on pure tin and tin lead plated capacitors
Johanson Dielectrics performed tin whisker testing on various sizes of capacitors using
iNEMI and JESDA121 test methods.
The following samples were tested:
0805 X7R Pure Matte Tin Finish with nickel barrier
1210 X7R Pure Matte Tin Finish with nickel barrier
1210 X7R Tin Lead Finish with 5% minimum lead content (same lot as pure tin part)
1812 X7R Pure Matte Tin Finish with nickel barrier
Two different tests were performed:
- Temperature Cycle Test:
Temperature Cycle per JESD22-A104 Test Condition A Soak Mode 3 1000 cycles
SEM inspections per JESD22-A121.
The parts are temperature cycled from -55C to 85C, with a minimum of 10 minutes soak
time at the minimum and maximum temperatures.
- Temperature Humidity Test:
4000 hours at 60 C and 93% relative humidity per iNEMI recommendations.
Inspection of whiskers:
The capacitors were inspected by SEM before and after each test at 250 and 2500
magnification.
The parts were evaluated to the requirements of Class 2 devices as stipulated by iNEMI
‘Tin Whisker Acceptance Test Requirements’, July 28, 2004, paragraph 18.2.3. The
maximum acceptable whisker length is 40 um.
The whisker length reported is the total axial whisker length as per JEDEC standard
JESD22A121 definition 3.1. Although only whiskers of 10um or greater in length are
classified as ‘true’ whiskers as per JEDEC standard JESD22A121 definition 3.2,
whiskers of all lengths are reported below. |
