Manassas, VA, United States
Manassas, VA, United States

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Tosun U.,ZESTRON America | Vargas A.,ZESTRON America | Kim B.,Pressure Products Company
IPC APEX EXPO 2014 | Year: 2014

Historically, the determination of the concentration of cleaning agent in high precision electronic cleaning baths has depended on any one of several possible measurable parameters. Refractive Index (RI) is by far the most common. RI methods are excellent tools for use in simple systems where a single solute dominates the signal. In these situations, it is possible to characterize and calibrate how that solute affects the signal. However, the introduction of flux residues during the wash bath lifetime complicates the bath chemistry/physics to such an extent that RI signals no longer provide the same insight. The introduction of flux residue has an enormous influence on the Refractive Index. Alternative means of measuring cleaning agent are necessary if cleaning agent concentration is to be known throughout the life of the bath. With a means to accurately measure bath cleaning agent, closed loop automated process control on the cleaning bath is possible; automating this labor intensive step in the production of electronic boards. We have found that acoustic measurements of cleaning bath solution are relatively independent of pH, conductivity, and dissolved solids in some of the most flux loaded baths. Utilizing acoustic sensing technology, field data was gathered from two beta site locations assessing the accuracy of the technology in fresh as well as contaminated wash baths.


Wack H.,Zestron America | Becht J.,Zestron America | Tosun U.,Zestron America | Schweigart H.,Zestron Europe | Afshari S.,RMD Instruments
SMT Surface Mount Technology Magazine | Year: 2011

Can an existing chemistry-based cleaning process be used to clean eutectic and lead-free alloys in the same process? A study, detailed in the following article, was created to provide valid technical data to better assess the risk associated with using one cleaning machine for both eutectic and lead-free substrates.


Schweigart H.,ZESTRON Europe | Tosun U.,ZESTRON America
SMT Surface Mount Technology Magazine | Year: 2011

Conformal coatings are applied to circuits boards used in high-reliability applications in the military, aerospace, communication, medical and automotive industries that demand a guaranteed, long-term product life. To guarantee the optimum adhesion of the protective coating and prevent formations of cracks or delamination, it is of utmost importance to ensure the highest cleanliness level of the assemblies prior to coating. While assessing the surface's cleanliness according to the J-STD 001E, a high ionic equivalent value indicates the existence of a large amount of hygroscopic impurities. In accordance with J-STD 001E, the presence of organic impurities can either be tested with infrared spectroscopy or detected with a quick and easy-to-use discoloration method such as the flux test. the integration of a cleaning process is usually required to be able to maintain all of the production thresholds set by J-STD 001E.


Tosun U.,ZESTRON America | Ravindran N.,ZESTRON America | McCutchen M.,ZESTRON America
SMT Surface Mount Technology Magazine | Year: 2012

OSP is a reliable surface finish method, but care must be taken during the SMT process to minimize surface thickness degradation, particularly due to reflow and cleaning. The results of this study detail the effect of chemically-assisted cleaning on OSP film thickness.


Wack H.,Zestron America | Tosun U.,Zestron America | Patel J.,Zestron America
SMT Surface Mount Technology Magazine | Year: 2012

Cleaning is a critical process in the electronics manufacturing industry. Effective cleaning improves product reliability by ensuring optimal surface resistance and preventing current leakage that can lead to PCB failure. This paper addresses the cleanliness level of packageon-package (PoP) assemblies, including underneath PoP components and in between packages.


Tosun U.,ZESTRON America | Parthasarathy R.,ZESTRON America | McCutchen M.,ZESTRON America
IPC APEX EXPO Conference and Exhibition 2013, APEX EXPO 2013 | Year: 2013

For mission critical electronics or Class III products, such as those used within the military, aerospace and medical industries, highest electronic reliability is a requirement as failure is not an option. Within the electronics industry, this means that residues, either ionic or non-ionic, must be fully removed. Partially removed or untouched residues can lead to component and product failures resulting from electrochemical migration, dendrite growth and electrical leakage currents. The goal of this study was to identify and qualify an aqueous cleaning process capable of removing combinations of no-clean flux residues for Class III electronic assemblies. Teamed with a global electronic manufacturing service (EMS) provider supplying electronics to the aerospace and medical industry, the Design of Experiment (DOE) developed was executed in two phases. Initial testing was completed utilizing EMS boards and final testing was validated using IPC test coupons and standards. The goals of each phase of the DOE were as follows: Phase 1: I. Determine optimum parameters to effectively clean flux residues from EMS board samples and verify cleanliness through visual inspection and ionic contamination analysis. Phase 2: I. Using the optimum parameters from Phase 1 above, clean additional EMS boards and verify cleanliness using Ion Chromatography (IC) and Solvent Extraction Conductivity (SEC) analyses. II. Conduct Surface Insulation Resistance (SIR) and Electrochemical Migration (ECM) analyses on IPC test coupons cleaned using parameters defined in Phase 1. III. Verify compatibility of all critical components and materials used on the boards with the selected cleaning agent. Through this DOE, the authors were able to identify and quantify the critical parameters impacting cleanliness for Class III electronic components as validated by numerous IPC assessment standards.


Wack H.,ZESTRON America | Tosun U.,ZESTRON America | Parthasarathy R.,ZESTRON America | Patel J.,ZESTRON America
IPC APEX EXPO Technical Conference 2010 | Year: 2010

While most cleaning processes in the global electronics manufacturing industry still rely on cleaning with DI-water only (for OA flux removal), recent studies suggest that water is beginning to reach its cleaning limitation, favoring the use of chemically assisted cleaning processes. The increased use of water-soluble lead-free solder requires more activators and higher soldering temperatures, which result in more burnt-in fluxes and produce water insoluble contamination. DI-water alone has a limited to no ability to solubilize non-ionic residues on the board's surface. These findings coincide with the use of smaller, more densely packed components which further limit the effectiveness of pure DI-water. Due to its high surface tension of over 70 dynes/cm, water cannot effectively penetrate underneath low standoff components. Chemistry assisted cleaning processes, however, can reduce the surface tension to 30 dynes/cm and below and therefore eliminate penetration problems. This technical case study complements the authors' initial in-house findings by comparing them to actual production assemblies and conditions. The lead engineering team at a participating customer site designed this comprehensive blind study to determine removability with DI-water versus various chemistry supported systems. The findings revealed significant experimental data, which shed much needed light on this emerging industry challenge.


Patel J.,ZESTRON America | Tosun U.,ZESTRON America | McCutchen M.,ZESTRON America
SMT Surface Mount Technology Magazine | Year: 2013

Summary: In the electronics manufacturing industry, pure DI-water processes are prevalent for removing water soluble (OA) flux residues. However, recent industry developments, as well as customer case studies, have shown that these wateronly processes may no longer produce the required cleanliness levels and thereby guarantee the longterm reliability of assemblies.

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