Electronics Assembly Knowledge, Vision & Wisdom
SN-CU-NI Composite Solder Paste High Temperature Use
SN-CU-NI Composite Solder Paste High Temperature Use
Research on a prototype paste is being completed to improve reliability and survivability of PCB and SMT solder joints under extreme temperatures (< 500° Celsius).
Production Floor

Production Floor programs cover topics including:
CAD/CAM/CIM/EDA, Circuit Board Handling, Clean Room, Cleaning Operations, Component Insertion, Component Prep, Dispensing, Feeders, Fume Extraction, Hand Tools, Labeling/Marking, Lasers, Material Handling, Odd Form, Ovens/Curing, Packaging, Stencil Printing, Repair/Rework, Soldering and more.
Submit A Comment
Comments are reviewed prior to posting. You must include your full name to have your comments posted. We will not post your email address.

Your Name

Your Company

Your E-mail

Your Country

Your Comment

Authored By:
S.M. Choquette1 and I.E. Anderson
Iowa State University
Ames, IA, USA

Continued research on a prototype paste, consisting of a composite mixture of SN100C (Sn-0.7Cu-.05Ni+0.01Ge) commercial solder powder and Ames Lab's gas atomized Cu-10Ni, wt.%, powder is being completed to improve the reliability and survivability of PCB and SMT solder joints operating under extreme temperatures (< 500 Celsius). The designed paste is predicted to be nearly 4,000 times less expensive than the currently available HTLF (hightemperature lead-free) solder Au-20Sn, wt.%, and able to withstand higher temperatures while still maintaining a standard commercial processing temperature of 250 Celsius.

The paste performs using liquid-phase diffusion bonding (LPDB) of the high-melting Cu-10Ni powders into the low melting SN100C to form the room-temperature stable intermetallic compound (IMC) (Cu,Ni)6Sn5. The nickel addition to this high-temperature phase increases joint ductility by suppressing the transformation of the IMC into the brittle low-temperature phase that would otherwise occur. Current research includes exploring the effect that powder size has on void formation in the joint. Existing results suggest that this composite solder could be a superior "drop-in" replacement for the Pb-based high-temperature solders that will soon be eliminated by RoHS restrictions.

From this experiment, two blends of Cu-10Ni composite pastes with varying Sn-alloy powder sizes were tested for their porosity. On average, the paste containing the smaller SN100C powder size (Type 6, 5-15 μm) resulted in solder joints with less porosity. The smaller powder size also helped create a more complete bond with the joint's substrate. The compositions of the phases were all as desired, including the previously unmodified (with Ni) IMC phase lining the Cu substrate.

Initially Published in the SMTA Proceedings

No comments have been submitted to date.
Free Newsletter Subscription
Every issue of the Circuit Insight email newsletter will bring you the latest information on the issues affecting you and your company.

Insert Your Email Address

Directory Search

Program Search
Related Programs
bullet Effect of Encapsulation Materials on Tensile Stress
bullet Reliability of Polymeric Encapsulation Materials on SnAgCu Solder Joints
bullet Lower Temperature Solder Joint Encapsulant
bullet Thermally, Electrically Conductive Adhesive to Control Heat in PCBs
bullet How to Protect Internal Circuitry from a Harsh Environment
bullet Fine Pitch Flip Chip Assembly Process Underfill, Evaluation and Reliability
bullet The Importance of Conformal Coating Thickness and Edge Coverage
bullet Conformal Coating - Performance Comparison Environmental Testing
bullet DFX on High Density Assemblies
bullet Shelf Life Before Conformal Coating
More Related Programs