Technical Library | 2020-03-09 10:50:17.0
A customer called the Helpline seeking advice for cleaning no-clean fluxes prior to applying a conformal coating. The customer's assemblies were manufactured with a no-clean rosin based solder paste (ROL0) and were cleaned with an isopropyl alcohol (IPA) wash. After cleaning, a white residue was sometimes found in areas with high paste concentrations and was interfering with the adhesion of the conformal coating (Figure 1). For conformal coatings to adhere properly, the printed circuit board (PCB) surface must be clean of fluxes and other residues. In addition, ionic contamination left by flux residues can lead to corrosion and dendrite growth, two common causes of electronic opens and shorts. Other residues can lead to unwanted impedance and physical interference with moving parts.
Technical Library | 2020-04-14 15:56:32.0
This paper will focus on the application requirements of solder printing small aperture designs, concentrating on 008004 (inch) / 0201 (metric) size components, and the results of a design of experiment printing these challenging apertures. As Moore's law continues to be applied to component miniaturization, the next installment of reduced packaging has arrived in the form of the 008004/0201 for resistors and capacitors. Component size roughly the size of a grain of sand presents specific challenges to the solder printing process. To address these challenges, each aspect of the printing process will need be examined. This includes essential machine requirements, including correct squeegee blades, tooling support, and calibrations, to meet the demanding specifications. The correct match and design of materials will be addressed, focusing on the stencil and substrate design along with solder paste and cleaning solvent requirements. A design of experiment will be reviewed that applies the machine and materials discussed, including the printer and Solder Paste Inspection (SPI) setup and the specific machine parameters used. The results of these DOE's will then be closely examined.
Technical Library | 2019-05-29 23:10:30.0
There are times when a PCB prototype needs to be built quickly to test out a design. In such cases where it is known early on that there will be multiple iterations or that a "one and done" assembly will be made that there will be some SMT assemblers who choose to hand print solder paste onto the board using a "frameless" stencil. In such cases where hand printing is used, the consistency of the printing technique has typically been in question. Furthermore, the effectiveness of both the nanocoatings as well as the higher end stainless steel materials, which have been heretofore studied in controlled printing environments, will be evaluated for their impact on the hand printing process.The purpose of the study was to determine the effectiveness of select nanocoating materials as well as certain high end stainless steel stencil materials as they relate to the manual SMT printing process. A variety of nanocoatings were applied to SMT metal stencils and solder paste volume measurements were taken to compare the effectiveness.
Technical Library | 1999-05-09 12:36:40.0
The production of electronics began with hand soldering, followed by manual cleaning, which reached its peak during the NASA program. Each step in the process tended to be considered on a stand alone basis, without thought being given to the preceding and following steps. Since each step had its own set of specifications, this led to a "patchwork" approach to overall quality.
Technical Library | 2023-05-07 19:26:34.0
Misprint Circuit Assemblies ■ Cleaning misprints is a production gap ■ Commonly cleaned in stencil cleaning equipment ■ Stencil Cleaning equipment allows for the + Collection and filtration of wet solder paste ■ Stencil Cleaning equipment short comings + Inability to clean B-Side misprints + Poor rinse quality 3
Technical Library | 2013-03-12 13:25:18.0
High density and miniaturized circuit assemblies challenge the solder paste printing process. The use of small components such as 0201, 01005 and μBGA devices require good paste release to prevent solder paste bridging and misalignment. When placing these miniaturized components, taller paste deposits are often required. To improve solder paste deposition, a nano-coating is applied to laser cut stencils to improve transfer efficiency. One concern is the compatibility of the nano-coating with cleaning agents used in understencil wipe and stencil cleaning. The purpose of this research is to test the chemical compatibility of common cleaning agents used in understencil wipe and stencil cleaning processes.Compatibility of Cleaning Agents With Nano-Coated Stencils
Technical Library | 1999-05-07 11:24:21.0
Many manufacturers have now completed the conversion to no clean solder paste. Many factors governed this initial conversion, among those being cosmetics, solder ability, and process ability. In circuit testing or probing through no clean solder paste residues has topically not been a major factor in the conversion decision for several reasons. Due to board design, solder paste was only used on one side of the board and not subjected to testing...
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 | 2022-02-16 15:34:32.0
Because of the phase-out of CFCs and HCFCs, standard solder pastes and fluxes evolved from RA and RMA fluxes to No-Clean, to low residue No-Clean, to very low residue No-Clean. Many companies came out with their cleaning solutions, aqueous and semi-aqueous, with each product release being more innovative than the previous one. Unfortunately for most of the suppliers of cleaners, two other trends appeared; lead-free soldering and the progressive miniaturization of electronic devices
Technical Library | 2014-03-27 14:50:01.0
Because of the phase out of CFC's and HCFC's, standard solder pastes and fluxes evolved from RA and RMA fluxes, to No-Clean, to low residue No-Clean, to very low residue No-Clean. Many companies came out with their cleaning solutions, aqueous and semi-aqueous, with each product release being more innovative than the previous one. Unfortunately for most of the suppliers of cleaners, two other trends appeared; lead-free soldering and the progressive miniaturization of electronic devices.
