Technical Library | 2023-04-25 22:03:25.0
This report hopes to achieve several goals: 1. Determine the link between bare PWB contamination, soldered assembly contamination and long-term product reliability. 2. Establish measurable limits for bare PWB cleanliness as well as process control limits for both an aqueous as well as a water-soluble soldering process. 3. Determine whether there is any correlation between common, industry-accepted rose/modified rose (omegameter/ionograph type) testing and long term product reliability. 4. Determine the effect PWB plating finish (HASL, Immersion Silver and Cu OSP) has on both bare PWB contamination as well as soldered assembly in a no clean and water soluble process. 5. Determine whether there is a link between percentage of saponifier used to wash soldered assemblies and long-term reliability. 6. Establish a more cost-effective test for manufacturers to use as a process-monitoring tool.
Technical Library | 2015-02-05 20:25:41.0
In the past 20 yrs the solvent industry has gone through a great deal of change. In the early 1990s, CFC-113 and 1,1,1-trichloroethane were the workhorses of the industry. The Montreal Protocol to phase-out substances that deplete the Earth's protective Ozone Layer was implemented in the mid 1990s. After phase-out of the CFC solvents, the solvent industry fragmented to a variety of cleaning solutions. The electronics industry was a large user of CFC solvents and many of these applications changed to aqueous based cleaners (...) But those alternatives are now facing various problems: e.g. aqueous based cleaners use a lot of energy, require long drying times, use equipment that requires frequent maintenance, and require a large footprint; no-clean fluxes leave flux residues; and trichloroethylene and n-propyl bromide have toxicity issues. In response to these serious issues newer solvents and blends are being introduced in the marketplace
Technical Library | 2000-06-21 17:55:59.0
There was once a time when precision cleaning required minimal thought. Just about anything that was dirty could be placed inside a vapor degreaser and emerge clean and dry in a matter of minutes. Today, precision cleaning decisions are seemingly endless with ever-changing environmental regulations, user safety issues and product compatibility concerns. Technologies range from spray-in-atmosphere to ultrasonics to spray under immersion using aqueous, solvent or semiaqueous chemistries. Which method works and with what chemistry? Will the process be safe or even allowed by the regulating agencies?
Technical Library | 2009-01-21 23:16:14.0
This paper describes a new approach to drying circuit board assemblies that significantly reduces the cost of ownership of an aqueous cleaning system. Drying performance is increased through a hybrid drying process that reduces energy input, exhaust requirements and sound levels. The combination of high temperature blow-off and convection brings the flexibility to tailor drying performance to fit the product's drying requirements.
Technical Library | 2009-03-19 20:23:54.0
Over the past several years, post-reflow defluxing of circuit assemblies has gained in popularity. Microminiaturization of components and boards, combined with higher expected reliability and increased product liability, have contributed to the prominence of defluxing. Lead-free solder paste - with its higher reflow temperatures and negative effects on flux - increase the likelihood of post-reflow defluxing to increase a product's reliability and aesthetic appearance.
Technical Library | 2009-09-18 14:52:06.0
Electronic assembly cleaning processes are becoming increasingly more complex because of global environmental mandates and customer driven product performance requirements. Manufacturing strategies today require process equivalence. That is to say, if a product is made or modified in different locations or processes around the world, the result should be the same. If cleaning is a requirement, will existing electronic assembly cleaning processes meet the challenge? Innovative cleaning fluid and cleaning equipment designs provide improved functionality in both batch and continuous inline cleaning processes. The purpose of this designed experiment is to report optimized cleaning process parameters for removing lead-free flux residues on populated circuit assemblies using innovative cleaning fluid and batch cleaning equipment designs.
Technical Library | 2009-09-18 14:48:58.0
The stencil cleaner can be one of the most versatile tools on the manufacturing floor. It can be used to clean electronic modules in various stages of the manufacturing process. In fact, an automated stencil cleaner can clean just about anything you come up against in your PCB assembly process.
Technical Library | 2019-08-14 22:20:55.0
Cleanliness is a product of design, including component density, standoff height and the cleaning equipment’s ability to deliver the cleaning agent to the source of residue. The presence of manufacturing process soil, such as flux residue, incompletely activated flux, incompletely cured solder masks, debris from handling and processing fixtures, and incomplete removal of cleaning fluids can hinder the functional lifetime of the product. Contaminates trapped under a component are more problematic to failure. Advanced test methods are needed to obtain "objective evidence" for removing flux residues under leadless components.Cleaning process performance is a function of cleaning capacity and defined cleanliness. Cleaning performance can be influenced by the PCB design, cleaning material, cleaning machine, reflow conditions and a wide range of process parameters.This research project is designed to study visual flux residues trapped under the bottom termination of leadless components. This paper will research a non-destructive visual method that can be used to study the cleanability of solder pastes, cleaning material effectiveness for the soil, cleaning machine effectiveness and process parameters needed to render a clean part.
Technical Library | 2016-08-04 14:33:23.0
Solder paste screen printing is known to be one of the most difficult processes to quality assure in Printed Board Assembly (PBA) manufacturing. An important process step in solder paste screen printing is the under stencil cleaning process and one of the key materials in this process is the cleaning paper1. This, often neglected, material affects the cleaning process and thereby also the print quality. It is therefore important to perform tests of different cleaning papers before one could be chosen. This article describes how cleaning papers can be tested and it also tells how big differences it can be between different materials.
Technical Library | 2009-07-09 17:23:07.0
Sometimes you just cannot clean with water. Good examples of this are: circuits with batteries attached, cleaning prior to encapsulation, ionic cleanliness testing, and non-sealed or other water sensitive parts. High impedance or high voltage circuits need to be cleaned of flux residues and other soils to maximize performance and reliability and, in these types of circuits; water can be just as detrimental as fluxes. When solvent cleaning is called for, Hansen solubility parameters can help target the best solvent or solvent blend to remove the residue of interest, and prevent degradation of the assembly being manufactured. In short, using this approach can time, manufacturing cost and reduce product liability.
