DfR-DESIGN for RINSE-ABILITY: EFFECT OF SMT COMPONENT PACKAGE DESIGN ON CLEANING EFFECTIVENESS

Reliability Society

NORMAN ARMENDARIZ, PHD, ENGR FELLOW, RAYTHEON, ANDOVER, MA

PRESENTATION: Recent CCAs-circuit card assemblies manufactured using SMT-surface mount technology processes have exhibited cleaning residues remaining on the surface of components and within electronic component / package housings with discoloration (degradation) of Cu-wire insulation and discoloration (oxidation) of the metal contacts observed, which may compromise the surface conformal coating properties, and possibly degrade the component’s electrical performance and long-term reliability.

Given that military applications require a high level of performance and reliability, CCAs- circuit card assemblies and components undergo a semi-aqueous chemical cleaning process after SMT-surface mount technology assembly in order to properly prepare CCAs for the conformal coating process and protect the electronic components as intended from moisture and harsh environments.

However, if any active cleaning constituents and un-reacted by-products are not removed or rinsed completely from the surface or from within the components, then the surface may not be suitable for subsequent conformal coating, and may also result in materials degradation and/or corrosion, which may detrimentally affect the electrical performance, if entrapped within the components.

This paper will discuss the “physics” of liquid entrainment / entrapment / cleaning / rinsing and their effects on component materials with experiments performed to determine the, major component design parameters required to adequately aqueous-rinse components of their cleaning residues with the objective of developing and providing “Design for Rinse-ability” guidelines to deploy. In addition, accelerated humidity testing with electrical testing will be discussed, that was performed to determine the degree of degradation / corrosion or electrical reliability of components exposed to cleaning chemistries.

AUTHOR BIO: Norman Armendariz is an Engineering Fellow at Raytheon responsible for materials engineering design, materials analysis, process equipment development, production support and technology roadmaps associated with the manufacturing of CCA- circuit card assemblies used in missiles, smart munitions, ground based radars, and mobile sensors across multiple US and international sites.

Norm has over 25 years of industrial experience, having worked for Lockheed/NASA, Motorola, Intel, Texas Instruments and American University.
He holds an interdisciplinary PhD in Chemical Engineering from New Mexico State University, MS in Materials Science Engineering from the University of Illinois at Urbana-Champaign, and BS Metallurgical Engineering from Colorado State University, with 9 US patents and 29 peer-reviewed publications.

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