how to manage wave solder alloy contamination
TRANSCRIPT
![Page 1: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/1.jpg)
How to manage wave
solder alloy
contaminations
Gerjan Diepstraten & Harry Trip
Cobar Europe BV
Balver Zinn
![Page 2: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/2.jpg)
Content
• SnPb solder and impurities
• Lead-free solder change
• Pb contaminations in lead-free
• Measure solder composition
• Sample interval
• Recommendations
• Wave soldering versus selective
![Page 3: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/3.jpg)
![Page 4: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/4.jpg)
SnPb impurities
Limits according to IPC-J-STD001E
Scores from >1500 solder pot analysis
Out of specification:
![Page 5: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/5.jpg)
Copper contamination in SnPb
Maximum 0,3%
Remove at 190 °C with stainless
steel strainer
![Page 6: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/6.jpg)
Exchange solder
Procedure:
1. Empty solder pot
2. Clean all parts
3. Refill pot with pure Sn
(wash Sn)
4. Run solder pumps for >
0,5 hour
4. Empty solder pot
5. Refill solder pot with lead-
free solder
![Page 7: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/7.jpg)
Solder exchange – Sn wash
Percentage of Pb after
lead-free refill
Use wash Sn to get low
Pb impurities
![Page 8: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/8.jpg)
Spectro analysis
1. Sample: flowing solder
middle of the wave
2. Preparation sample
3. OES Analysis
![Page 9: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/9.jpg)
Erosion solder pot
Lead-free:
• Higher solder
temperatures
• Higher Ag & Sn content
• Lack of Pb lubricationErosion
Potential alternatives:
Titanium
Cast iron
Chrome carbid
Ag-less alloys
![Page 10: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/10.jpg)
Fe contamination
• FeSn2 needles
• SAC alloys sensitive for
erosion
• Co or Ni doping to minimize
erosion
Fe Max. Values 0,02 %
![Page 11: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/11.jpg)
SPC Chart Fe contamination
FeSn2 needles:
• Melting point >500 °C
• In areas where there is
no flow
• Bridging potentials
Hard to define iron
erosion by analyzing
solder samples
![Page 12: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/12.jpg)
FeSn2 Needles Selective SnPb
Also in SnPb alloys there is steel erosion.
Reduces flow properties.
![Page 13: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/13.jpg)
Pb impurity historical graph
![Page 14: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/14.jpg)
Copper leaching
SAC305
SnPb
SN100C
![Page 15: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/15.jpg)
SPC: Cu content in solder
Nitrogen wave solder
process (full tunnel)
(identical machines,
same customer):
Automotive,
Medical products
(SnPb)
Industrial (lead-free)
SnPB
SN100C
![Page 16: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/16.jpg)
Ni additive
Cu6Sn5 IMC
at ~ 3 % Ni in (Cu,Ni)6Sn5
Sn-0.7Cu+NiGe
Sn-0.7Cu
(Cu,Ni)6Sn5
![Page 17: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/17.jpg)
Fluidity and Ni Content
Flu
idity
Len
gth
![Page 18: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/18.jpg)
IMC growth
The Ni in the IMC has the effect of stabilizing the
hexagonal crystal structure of the Cu6Sn5 and slowing
down total IMC growth
![Page 19: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/19.jpg)
Ni SPC-chart SN100C
Ni content is consistent over the years.
Ni-rich solder bars available.
![Page 20: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/20.jpg)
High Ni contentUniform eutectic
structure
Primary
(Cu,Ni)6Sn5
Crystals
Eutectic
between
crystals
600 PPM >1000 PPM
SN100C
![Page 21: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/21.jpg)
Impact of Ag on fluidity
![Page 22: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/22.jpg)
SAC 305 elements contents
Selective soldering
process
Cu drifts more due:
1. Leaching
2. SnAg or SAC bars
![Page 23: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/23.jpg)
Silver/copper content in SAC305
Higher melting
range:
• Fast solidification
of solder
• Bridging
• Spikes
![Page 24: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/24.jpg)
Germanium
Ge acts as an antioxidant and surface active agent.
15 minutes ramp up to 340 °C - 30 minutes
cooling
K Watling, A Chandler, K Nogita. A Dahle, University of Queensland
SnCuNi SnCuNiGe
![Page 25: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/25.jpg)
Dross and Germanium
Less Ge results in more dross.
![Page 26: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/26.jpg)
Impact of P
Phosphorus in lead-free solder (SAC) increases stainless
steel erosion. P acts like a flux.
Adding P to SnCuNi destroys the beneficial effect of Ni.
SnCuNi+0.02PSnCuNi+0.007P SnCuNi+0.06PSnCuNi
Sn0.7Cu
Similar – Ni benefit gone
![Page 27: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/27.jpg)
SAC alloys out of spec
Number of Pb defects is decreasing
Ni is less critical
![Page 28: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/28.jpg)
Sampling interval
Trend 0,032%/week
Trend 0,29%/week
10x more
![Page 29: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/29.jpg)
Recommendations
IPC J-STD-001E chapter 3.2.2. Solder Purity Maintenance:
“If contamination exceed limits, intervals between the analyses, replacement or replenishment shall [N1D2D3] be shortened.”
“The frequency of analysis should be dertermined on the basis of historical data or montly analysis.”
![Page 30: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/30.jpg)
Dross
After running 20 hours
(no maintenance)
Solder (wave) continuous
running. Solder temperature
260 C.
![Page 31: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/31.jpg)
Minimize dross
• Use Nitrogen blanket
• Reduce solder fall height
• Ge tablets
• Wave former
![Page 32: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/32.jpg)
SnPb wave versus selective
Automotive line (identical products)
One year average scores
![Page 33: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/33.jpg)
Periodic table
Pr CeGd
LaSm
Nd
Halogens
Rare Earth elements
RoHS
Anti-oxidants
(Vitamins)
![Page 34: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/34.jpg)
Conclusions:
• Lead-free soldering requires more alloy analyses.
• Copper contents in lead-free solder alloys should
be monitored on a frequently basis.
(Minimal 12 x /year for selective soldering)
• Lead impurities are decreasing in lead-free
alloys.
• Metal erosion (solder pot parts) is hard to
identify by solder analysis. Check during
maintenance.
![Page 35: How to manage wave solder alloy contamination](https://reader033.vdocuments.us/reader033/viewer/2022050800/586bb08b1a28ab45488ba414/html5/thumbnails/35.jpg)
Acknowledgement
• Balver Lab
• Nihon Superior