The SMT Process:
PCB Build to Reliability Assessment Workshop
June 20, 2017
11285 Assett Loop
Manassas, VA 20109
Optimizing Printing for Small Apertures through Design, Machine and Process Parameters to Eliminate Printing Defects
Chris Hill, Eastern Regional Sales Manager - ITW/EAE
Increasingly fine pitch component patterns on PCBs, and ever-smaller passive components such as 03015s continue to narrow the
process window for PCB assemblers. Thinner stencils, smaller particle size solder paste, and smaller apertures, where even aperture
shape becomes a factor in testing the limits of a successful printing process. Printing machine technology continues to advance to
meet the fine-pitch challenge, with greater precision and motion control, closed-loop feedback systems, enhanced software tools
and machine vision assists, and many other developments and innovations designed to enable successful and repeatable fine pitch
solder paste printing for high-density SMT assemblies. This presentation details those developments, and illustrates how they are
impact the solder paste printing yield.
Thermal Profiling and Post Reflow Processing Issues
Tad Formella, Senior Applications Engineer - ITW/EAE
Reflow soldering process comprises of multiple precisely controlled thermal stages that soldered assemblies are exposed to.
Process engineers are challenged with complex structure of printed circuit boards where specifications for all elements of processed
assembly; substrate, components and solder paste have to be exposed to a thermal process. Each assembly has its own thermal
characteristics thus thermal profiling is essential for creating of specific settings of a reflow oven. Neglecting profiling requirement
may result in post reflow processing issues and may compromise the reliability of the assembly.
Improvements in Yield and Reliability for SMT Processes via Cleaning
Ravi Parthasarathy, M.S.Ch.E - ZESTRON
Trends within the electronics industry, including miniaturized components, increased board density and reduced standoff heights,
are driving the need for precision cleaning. This presentation discusses how to implement yield and reliability improvements to the
SMT process via cleaning from print to final assembly. Process control including wash bath and concentration monitoring methods
will be addressed.
Collateral Cleaning - The Unintended Consequences of Cleaning Electronic Assemblies
Mike Konrad, President / CTO - Aqueous Technologies
The decade between 1989 and 1999 witnessed the abolishment of the most popular cleaning solvents due to environmental
concerns, putting into motion a domino effect of change within the electronic assembly industry. It is said, “necessity is the mother
of invention”. In this case, the dominos began falling in two directions. One direction lead to the introduction of no-clean flux
technology, allowing assemblies to be reflowed without the need to remove residues. The other direction included alternate cleaning
technologies, utilizing environmentally safe cleaning methods. Almost thirty years later, modern electronic assemblies are far less
tolerant of residues than their historical counterparts, putting into question the validity of knowingly allowing residues to remain on
assemblies. This presentation will review both the intended and unintended benefits of cleaning electronic assemblies.
Re-inventing the Wheel: Importance of Spray Technologies and Nozzle Configuration in the Cleaning Process
Jody Saultz, Application Engineer - ITW/EAE
In recent years, significant changes in solder paste formulations and assembly processes have occurred. Post reflow residues of tinlead
and newer lead-free soldering materials are more difficult to remove due to increases in component density, larger component
packages, higher lead counts, finer lead spacing and lower stand-off distances. While modern aqueous cleaning agents effectively
remove these flux residues, achieving satisfactory results often requires an increase in temperature, exposure time, chemical
concentration, and mechanical energy. Most board manufacturers strive to optimize their cleaning process to provide the best
cleaning performance over a broad range of board assemblies. This presentation covers the results from a designed experiment of
fluid dynamics across multiple types of spray technologies and nozzle configurations and the overall impact to cleaning performance
and process flexibility. The data collected and presented will capture the realization of cleaning electronics as well as industrial
cleaning and compare technologies of today versus the past. This shows why certain spray technologies and nozzle configurations
improve cleaning performance and improve process flexibility.
Where do the Contaminants Come From?
Terry Munson, CEO / Senior Consultant - Foresite
This presentation addresses the sources of contamination that come from the fabrication, assembly steps and environmental
operating conditions and why they cause electrical performance and mechanical adhesion problems. Analytical methods to
assess these residues including FTIR, SEM/EDX, Localized Extraction, and Ion Chromatography will be covered. A general primer
on fabrication and assembly processes and three case studies that discuss the effect of residues from the fabrication/assembly
process that impact reliability performance with both cleaning and no clean processes will be reviewed. This is not a presentation
on how clean is clean enough but a presentation on where are the contaminants coming from and what impact they may have
downstream on electrical and mechanical performance.