ZESTRON Americas

iNEMI Webinar 07.07.2021 - PCB Cleaning

Apr 11, 2022 | Stefan Strixner

Agenda  Why Cleaning of electronic assemblies? - Standards - Reliability - Subsequent processes  Cleaning processes - Cleaning chemicals - Cleaning machines  Cleaning process monitoring - Bath monitoring - Result monitoring  Process cost...

PCB Surface Finishes & The Cleaning Process - A Compatibility Study

Oct 20, 2021 | Umut Tosun, Naveen Ravindran

All PCBs that are manufactured require a surface finish to protect exposed copper on the surface which if left unprotected, can oxidize, rendering the board unusable. To address this issue, it is common to surface treat the PCB prior to assembly and reflow. The surface finish not only prevents oxidation of the underlying copper, but guarantees a solderable surface. A cost effective and widely used approach to PCB surface finish is HASL (Hot Air Solder Leveling). However, as circuit complexity and component density have increased, HASL has reached its limitations, necessitating the need for thinner coatings. Thus, coatings such as Immersion Tin (ImSn), Immersion Silver (ImAg), Organic Solderability Preservatives (OSP), and Electroless Nickel Immersion Gold (ENIG) are becoming more widely used....

Cleaning Before Conformal Coating

Oct 06, 2021 | Naveen Ravindran

Cleaning PCBs before conformal coating removes potentially harmful and unknown contaminants from the board's surface resulting in better adhesion of the conformal coating and thereby preventing delamination. Cleaning PCBs can ultimately prevent issues like leakage current, electrochemical migration and coating failures. From a production standpoint, it can help to decrease the cost of labor and time needed for the re-work of the boards....

Higher Defluxing Temperature and Low Standoff Component Cleaning - A Connection?

Nov 04, 2020 | Jigar Patel and Umut Tosun

OEMs and CMs designing and building electronic assemblies for high reliability applications are typically faced with a decision to clean or not to clean the assembly. If ionic residues remain on the substrate surface, potential failure mechanisms, including dendritic growth by electrochemical migration reaction and leakage current, may result. These failures have been well documented. If a decision to clean substrates is made, there are numerous cleaning process options available. For defluxing applications, the most common systems are spray-in-air, employing either batch or inline cleaning equipment and an engineered aqueous based cleaning agent. Regardless of the type of cleaning process adopted, effective cleaning of post solder residue requires chemical, thermal and mechanical energies. The chemical energy is derived from the engineered cleaning agent; the thermal energy from the increased temperature of the cleaning agent, and the mechanical energy from the pump system employed within the cleaning equipment. The pump system, which includes spray pressure, spray bar configuration and nozzle selection, is optimized for the specific process to create an efficient cleaning system. As board density has increased and component standoff heights have decreased, cleaning processes are steadily challenged. Over time, cleaning agent formulations have advanced to match new solder paste developments, spray system configurations have improved, and wash temperatures (thermal energy) have been limited to a maximum of 160ºF. In most cases, this is due to thermal limitations of the materials used to build the polymer-based cleaning equipment. Building equipment out of stainless steel is an option, but one that may be cost prohibitive. Given the maximum allowable wash temperature, difficult cleaning applications are met by increasing the wash exposure time; including reducing the conveyor speed of inline cleaners or extending wash time in batch cleaners. Although this yields effective cleaning results, process productivity may be compromised. However, high temperature resistant polymer materials, capable of withstanding a 180°F wash temperature, are now available and can be used in cleaning equipment builds. For this study, the authors explored the potential for increasing cleaning process efficiency as a result of an increase in thermal energy due to the use of higher wash temperature. The cleaning equipment selected was an inline cleaner built with high temperature resistant polymer material. For the analysis, standard substrates were used. These were populated with numerous low standoff chip cap components and soldered with both no-clean tin-lead and lead-free solder pastes. Two aqueous based cleaning agents were selected, and multiple wash temperatures and wash exposure times were evaluated. Cleanliness assessments were made through visual analysis of under-component inspection, as well as localized extraction and Ion Chromatography in accordance with current IPC standards....

ph Neutral Cleaning Agents - Market Expectation & Field Performance

Feb 25, 2016 | Umut Tosun, Jigar Patel, Kalyan Nukula, Fernando Gazcon, ZESTRON America

With regard to precision cleaning applications within electronics manufacturing, pH neutral product development was a major breakthrough in recent years. The impetus for this development resulted from changes with regard to solder paste formulations and resulting assembly processes.</p><p>The greater use of lead-free solder paste and the required higher reflow profiles have resulted in even more difficult to remove burnt-in flux residues. Coupled with increases in component density, larger component packages, higher lead counts, finer lead spacing, and lower standoff distances, effective cleaning is greatly challenged. The aqueous alkaline based cleaning agents can effectively remove these flux residues, however, the process often requires an increase in wash temperature and exposure time, chemical concentration, and mechanical energy. Although an efficient and effective cleaning process can be developed, oftentimes, the required operating parameters present a new set of challenges with regard to material compatibility.</p><p>Since their introduction, the newly developed pH neutral formulations have proven to be capable not only of removing these difficult post reflow residues from complex board geometries, but do so without affecting material compatibility of sensitive components. Additionally, they perform at low concentration levels. This study reviews the performance of pH neutral cleaning agents as compared to alkaline cleaning agent alternatives and includes field data demonstrating their effectiveness with regard to material compatibility and cleaning performance....

Back to Basics – Why Clean?

Jun 28, 2011 | ZESTRON

ZESTRON America’s spring edition of ZESTRON News goes back to basics providing the latest information on the topics of cleaning in the electronics manufacturing industry....

Why Switch From Pure DI-Water to Chemistry

Dec 22, 2009 | Dr. Harald Wack, Umut Tosun, M.S.Chem.Eng., Dr. Joachim Becht, Dr. Helmut Schweigart

While most cleaning applications in the North American market rely on cleaning with DI-water only, for removing OA fluxes in first place, recent market studies show that water has reached its limitations in cleaning performance while favoring usage of aqueous processes. The term aqueous implies the use of aqueous-based chemistries with active ingredients and are usually diluted with DI-water. The nature of these active ingredients in the aqueous chemistries varies between manufacturer and his R&D knowledge. ...

Fluid Flow Mechanics Key To Low Standoff Cleaning

Sep 18, 2009 | Harald Wack, Ph.D., Umut Tosun, Naveen Ravindran, Sylvain Chamousset, Joachim Becht, Ph.D.; ZESTRON, Steve Stach, Austin American Technology Corp.

In recent years, various studies have been issued on cleaning under low standoff components; most however, with incomplete information. It is essential to revisit and describe the latest challenges in the market, identifying obvious gaps in available information. Such information is crucial for potential and existing users to fully address the cleanliness levels under their respective components. With the emergence of lead-free soldering and even smaller components, new challenges have arisen including cleaning in gaps of less than 1-mil....

Thermal Residue Fingerprinting: A Revolutionary Approach to Develop a Selective Cleaning Solution

Jul 01, 2009 | Steve Stach, Austin American Technology Harald Wack, Ph.D., Umut Tosun, Naveen Ravindran, ZESTRON America, John M. Radman, Daniel D. Phillips, Trace Laboratories East

During the last 5 years, the processes to remove flux residues especially for lead-free and challenging geometries have demonstrated new cleaning obstacles which have to be overcome.i A new methodology has been recently developed to further increase the propensity for successful cleaning.ii At the core of this method is the thermal identification of the residue matrix. Thermal energy changes the physical state, i.e. transitions between liquid, solid and gas phases. By taking advantage of such specific information during phase transitions, the cleaning process can be tailored to such settings, which in turn increases the cleaning success significantly....

Cleaning High-power Electronics

Jan 06, 2009 | Steve Stach, Austin America; Harald Wack, Ph.D., Naveen Ravindran, Zestron America; Joachim Becht, Zestron Europe

To prevent malfunctions in high-power electronics, flux residues must be removed from flip chip components prior to subsequent processes. As a result, integrating a suitable cleaning application into the manufacturing process of flip chip components is often required. Solvent based applications have re-emerged, and with that, an overall process solution is necessary....