Electronics Assembly Knowledge, Vision & Wisdom
Hybrid Conformal Coatings for Mitigating Tin Whiskers
Hybrid Conformal Coatings for Mitigating Tin Whiskers
In this stydy, nanoparticles were functionalized to bind them to the polymer structure while avoiding the collection among the particles.
Materials Tech

Materials Tech programs cover topics including:
Adhesives, Chemicals, Cleaning Solutions, Coatings, Components, Design, Embedded Technology, Fasteners, Finishes, Flex Circuits, Flip Chip, Fluxes, PC Fab, Solders, Solder Masks, Solder Paste 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:
Junghyun Cho, Suraj Maganty
Binghamton University (SUNY), Binghamton, NY, USA

Stephan J. Meschter
BAE Systems, Endicott, NY, USA

Dale Starkey, Mario Gomez, David G. Edwards
Henkel Electronic Materials LLC, Irvine, CA, USA

Abdullah Ekin, Kevin Elsken
Bayer MaterialScience LLC, Pittsburgh, PA, USA

Jason Keeping, Polina Snugovsky, Jeff Kennedy
Celestica Inc., Toronto, ON, Canada

Summary
A conformal coating of polyurethane (PU) consisting of hard and soft segments is being studied in an effort to prevent tin whisker penetration. For this, the coating needs to possess optimum mechanical properties by providing sufficient strength, modulus, and hardness while maintaining good ductility and toughness.

Typical monolithic PU films, however, do not possess all these required properties, so silica nanoparticles are incorporated into a PU film to improve its whisker mitigation effectiveness. In the present work, nanoparticles were functionalized to bind them to the polymer structure while avoiding the agglomeration among the particles.

Selection of the ideal concentration of nanoparticles is determined by establishing microstructure-property relations. Structural features at different length scales are characterized by various instruments including atomic force microscope (AFM) and scanning electron microscope (SEM) while mechanical properties are evaluated via macroscopic tensile testing as well as nanoindentation.

In particular, the nanoindentation testing emulates the whisker penetration behavior by producing local deformation of PU around an indenter tip.

Conclusions
Functionalized nanosilica particles approximately 20 nm in diameter were added to a PU coating in an attempt to attain its optimum mechanical properties for mitigating tin whisker growth. It was shown that mechanical properties do not continuously increase with the nanosilica concentration.

This was due to non-uniform distribution of nanosilica and polymer structure change with added nanoparticles. Phase separation also seemed to be affected by the presence of nanosilica. In particular, microdefects created during film processing are responsible for film brittleness and limited ductility.

Establishment of the structure - property relationship is essential to identify optimal microstructures of the nanoparticle-filled PU, which can be of importance in tin whisker mitigation.

Initially Published in the SMTA Proceedings

Comments
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 A Robot's Place in SMT
bullet How To Verify Cleanliness After Rework and Prior to Re-coating?
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 Improving Reliability Through HALT and HASS Testing
bullet The Importance of Conformal Coating Thickness and Edge Coverage
bullet DFX on High Density Assemblies
bullet Shelf Life Before Conformal Coating
bullet A Novel Conformal Back-Up Material
More Related Programs