Dendritic Growth & Corrosion Under Low-Standoff Components in...
Transcript of Dendritic Growth & Corrosion Under Low-Standoff Components in...
![Page 1: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/1.jpg)
1 5 Oct 2015 Karthik Vijay [email protected] +44 7584 643 677
Dendritic Growth & Corrosion Under Low-Standoff Components in Automotive Electronics
A Flux Solution…
![Page 2: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/2.jpg)
Indium Corporation
© Indium Corporation
![Page 3: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/3.jpg)
What is Solder Paste?
![Page 4: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/4.jpg)
No Clean Flux Technology
Activators - cleaning agent during reflow, Dissolves oxides off metal surfaces & promotes wetting
Rosin- Tacky and viscous, acts as an oxygen barrier
Gelling Agents – thickeners, Regulate viscosity and paste stability - rheological additives
Solvents - dissolve chemicals, activators, gelling agents, & resins to create a homogeneous paste
![Page 5: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/5.jpg)
Reflow Profiles Involved
5 INDIUM CORPORATION CONFIDENTIAL
![Page 6: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/6.jpg)
Halogen-Free No-Clean Fluxes
6 INDIUM CORPORATION CONFIDENTIAL
High SIR
Good Wetting Halogens may be
compensated with the use of large amount of hygroscopic organic acids Compromised SIR???
With more acids, rosin quantity that serves as oxygen barrier in the flux will have to be reduced to achieve adequate viscosity. Compromised Wetting???
![Page 7: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/7.jpg)
Oxidation & Smaller Paste Deposits
![Page 8: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/8.jpg)
SIR (Surface Insulation Resistance) J-STD-004B SIR, IPC-TM-650, 2.6.3.7
![Page 9: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/9.jpg)
ECM – Electrochemical Migration
![Page 10: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/10.jpg)
Automotive 1– More Stringent SIR Requirements
![Page 11: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/11.jpg)
Automotive 2– More Stringent SIR Requirements
• Exposure – Steady State : 40 deg C / 90% RH; 504 hrs – Damp Cycling: 25 deg C / 95% RH; 50 deg C /
90% RH; 144 hrs
• Space between Traces : 0.3mm
• Bias : 50V DC
• Resistance Criteria : 100 MΩ Lower Limit (8 log 10)
![Page 12: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/12.jpg)
12 INDIUM CORPORATION CONFIDENTIAL
Low-Standoff Components with Poor Ventilation For Large low stand-off components such as Power MOSFETs, QFN, LGA, during SMT assembly, flux outgassing/drying is difficult due to poor venting
![Page 13: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/13.jpg)
13 INDIUM CORPORATION CONFIDENTIAL
Automotive Customer Requirements Reflowed Flux Residue Exposed to: - Dry heat test
- 120 deg C for 500 hrs; 10V - 150 deg C for 500 hrs; 10V - 120 deg C for 504 hrs; 30V
- Heated oil @ 85 deg C for 10 days
Automotive - High Heat Storage & SIR Electrical Reliability
![Page 14: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/14.jpg)
Automotive - High Heat Storage Electrical Reliability for MOSFET Low-Standoff Component
PDSON Double-MOSFET device subject to Dry heat test - 120 deg C for 500
hrs; 10V - 150 deg C for 500
hrs; 10V - Dendritic growth
seen
![Page 15: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/15.jpg)
Standard J-Std 004B SIR Test to test flux under Low-Standoff Component
Paste
1
2
3
4
5
- No SIR failures - But test does not simulate flux trapped beneath a
low-standoff component
![Page 16: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/16.jpg)
J-Std 004B SIR Test with Glass Slide on Coupon to test flux under Low-Standoff Component
Paste
1
2
3
4
5
6
Barely Pass SIR
![Page 17: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/17.jpg)
RCOOH encapsulated in solid rosin, incapable of engaging in corrosion reaction
Activator RCOOH in flux
RCOO- + H+ mobile in liquid environment
Solvent dried out
H2O H+ engage in corrosion reaction
Solvent retained
Flux Activator & Solvents during Reflow of Low-Standoff Components
17
![Page 18: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/18.jpg)
Flux Chemistry Solution
• Make wet flux residue non-corrosive and non-conductive by going very low on activators and flux activity.
• But this would result in – Poor wetting – Head-in-Pillow (HiP)
18
How can the flux be designed so that - The wet flux residue is benign and does not cause
electrical failures - The flux activity is not compromised and achieve
good wetting and eliminate Head-in-Pillow
![Page 19: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/19.jpg)
Flux Chemistry Design SIR Electrical Reliability Test
1 √ 2 √
3 √ 4 √
5 √ I √
X 1 2
3 4
5 I
X
X X
X √
SIR - Standard SIR + Glass Slide
![Page 20: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/20.jpg)
Flux Chemistry Design Oxidation Barrier & Head-in-Pillow Test
Paste I
Paste 3
![Page 21: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/21.jpg)
Flux Chemistry Design Oxidation Barrier & Head-in-Pillow Test
21
1
2
3
4
5
I
x x
x
√ √
√
![Page 22: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/22.jpg)
Flux Performance Summary
Paste SIR-Glass
SIR-Std HIP Wet (air) Wet (N2)
Paste 1 x √ √ √ √
Paste 2 x √ √ √ √
Paste 3 x √ x √ √
Paste 4 x √ x x √
Paste 5 x √ x √ √
Paste I √ √ √ √ √
22
good acceptable unacceptable
![Page 23: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/23.jpg)
Summary
• Good SIR performance with wet flux residue demands low activator concentration or low corrosivity in the flux residue.
• Good wetting, and good HIP need good flux oxidation barrier capability and good fluxing capacity.
• The dilemma between good soldering performance versus low corrosivity can be resolved with a breakthrough in flux technology
• This flux solution is expected to have better resistance for dewing tests as well
23
![Page 24: Dendritic Growth & Corrosion Under Low-Standoff Components in …thor.inemi.org/.../Dendritic_Growth_Vijay_100515.pdf · 2015. 10. 14. · 1 Karthik Vijay kvijay@indium.com +44 7584](https://reader035.fdocuments.in/reader035/viewer/2022071010/5fc8a6c33a6be83e6e4d77f1/html5/thumbnails/24.jpg)
Do it Right… Thank You