Test data requirements for assessment of alternative Pb-free solder alloys
Test and method Test parameters Control Report
Four-point bend Test condition: as per IPC-9702, support span at least 20 SnPb, • For each combination of PCB finish (OSP and Ni/Au) and for each
IPC-9702 mm longer than the load span; select the exact value to SAC405 paste or ball alloy combination, provide the strain [µε] at which
obtain a strain rate of 5000 µε/s (IPC-9702, Figure A.1) failure occurs.
Solder paste and BGA/CSP ball PCB: HP standardized test board conforming to IPC- • Report support span used.
alloys 9702, Section 8.3, 1 mm thick, 8 layers, 1+6+1 build-up,
both OSP and electrolytic Ni/Au (not ENIG), non solder-
mask defined (metal-defined) pads, Isola 408
Components: same as mechanical shock samples, area
arrays with silicon die and daisy chains as per IPC-9702,
Section 8.7, no PTH or lead frame components, package
surface finish OSP or SOP, one type of components (no
larger than 15 mm x 15 mm), BGAs/CSPs in the same
combinations as the vibration test.
Samples: Eight boards for each surface finish and solder
alloy combination (total of 64 boards). Four components
shall be mounted on each board, as described in IPC-
9702. Strain gauge locations: Six strain gauges attached
to each board, as specified in IPC-9702, Figure 8-4.
Failure criterion: 20% increase in daisy-chain resistance
TH joint strength Test condition: pin pull/push rate of 1 mm/min. SAC305 Plot force vs pin-wetted length for both the new alloy and SAC 305
Pin pull test as described in “Reli- PCB: Culebra test board, 0.130 inches thick, 16 layers, control on the same graph.
ability of Partially-Filled SAC305 Isola 408, OSP Enthone Entek 106HT, three boards per pin
Through-Hole Joints,” Holder, et al, finish, assembled in nominal process
APEX 2006 Components: DIMMs
Samples: Pull or push pins from two DIMM components
Wave and minipot alloys only per board, fifteen pins per component (90 pins per alloy)
Preconditioning:
• 400 g shock performed once per axis (or random
vibration 9 Grms), as per IEC 60068-2-64
• Followed by 1000 cycles 0°C to 100°C thermal cycle,
as described in IPC-9701A
Manufacturing
Test and method Test parameters Control Report
Design of experiment (DOE) for Variables and test conditions: SAC305 Provide data for new alloy and controls for all noted locations for
wave solder alloy • Pot temperature (°C): 240, 255, 270, 285, 300 all conditions:
(validated by thermocouple for each temperature) • Through hole fill results
HP wave process characterization • Contact time (sec): 3, 5, 7 (measured using a • Copper dissolution results
test method Lev-Check) Lambda wave only • Wetting angle
PCB: Culebra test board, 0.130 inches thick, 16 layers, • IMC thickness
Wave solder alloy only Isola 408 laminate, OSP Enthone Entek 106HT, variation in • Hot tearing evaluation
hole sizes embedded in design • Laminate defect evaluation andcopper via cracking evaluation
Components: DIMMs, headers, delay lines, all fully
loaded except J2 which is covered with tape (for copper Report equipment and process parameters:
dissolution evaluation) • Flux amount applied
Flux: Cookson RF800, datasheet recommended amount • Flux application method
Replicates: minimum of twice per new and control alloy • Air knife used
(five pot temperatures and three contact times, for a total • Conveyor angle
of 30 runs per alloy) • Solder level (height)
Preconditioning: PCBs preconditioned with two nominal • Pump speed
Pb-free reflow cycles • Preheat time and temperature, and how determined
Locations for TH fill measurement: J3, DL1, DL2,DL5,
DL6, DL7, DL8, DL9, DL10 Report yield and visual inspection results:
TH fill measurement: Measure on cross-sectioned • Number of shorts at 10x mag
joints (or 5DX) as an actual measurement in millimeters • Results of yield and visual inspection as per IPC-610
expressed as pin-wetted length
Locations for copper dissolution measurements: DL3,
DL4, DL11, and DL12
Copper dissolution measurement: Measure the remain-
ing copper of the TH pad and knee in cross-sections. J2
is the unpopulated sites for determination of the ‘original’
thicknesses.
Locations for wetting angle measurement, IMC
thickness measurement, hot tearing evaluation, and
laminate evaluations: DL line (cross section one row),
pin one at J3
Design of experiment (DOE) for Variables: SAC305 Report:
reflow solder alloy • Time above liquidus (TAL) (sec): 30, 65, 100 • Results and example photos of visual inspection to IPC-610
• Peak temperature (Tp) (°C): 230, 245, 260, 275,290 • Representative wetting angles at toe and heel fillet (averaged
HP reflow process characterization PCB: HP standardized test boards, 0.093 inches thick, at three locations)
test method Isola 408, 14 layers, OSP surface finish, non solder-mask • Results and example photos of x-ray inspection (either trans-
defined (metal-defined) pads for area array components mission or x-ray laminography) of BGAs to IPC-7095
Solder paste alloy only Components: Standardized BOM with BGAs with • Cross-section images:
SAC305 and SAC105, TSOPs with Ni/Pd/Au, Sn, and a) IMC thickness
SnPb finishes; BOM selected to ensure the following b) Copper dissolution
combinations: • SAC305 ball alloy and SAC305 paste • • Process parameters:
new alloy ball and new paste alloy • SAC305 ball alloy and a) Solder paste volume
new alloy paste • SAC105 ball alloy and new alloy paste b) Flux used in both pastes
Flux: same for both SAC305 and new alloy, optimize c) Reflow profiles as verified by thermocouples in joints
preheat temperature to flux
Replicates: twice (with three TAL levels and five Tp levels,
total of thirty runs for each alloy) Copper dissolution
measurement: On a cross-sectioned sample, measure the
remaining Cu on the SMT pad.
Wetting balance Test: F1 – Wetting Balance Test: Lead-free Solder SAC305 Provide data for the new alloy and SAC305 controls:
J-STD-003 Pot temperature: 255°C, as per standard for Pb-free • Wetting balance curves showing individual coupon results (not
alloys averaged) for each alloy
Flux: standard activated rosin flux #2 for Pb-free alloys • Contamination reports before an dafter test for both the new
Samples: 10 new alloy and 10 SAC305 control alloy and SAC305 control
Precondition: 8 hours at 72C/85% R.H. followed by • Test board thickness and features
1 hour bake at 105°C
Test conditions: Parts immersed at 45 degrees incident to
solder pot to a depth of 0.4 mm at 2 mm/sec
www.globalsmt.net Global SMT & Packaging – November 2008 – 15
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