Technical Library | 2020-11-24 23:01:04.0
The miniaturization trend is driving industry to adopting low standoff components or components in cavity. The cost reduction pressure is pushing telecommunication industry to combine assembly of components and electromagnetic shield in one single reflow process. As a result, the flux outgassing/drying is getting very difficult for devices due to poor venting channel. This resulted in insufficiently dried/burnt-off flux residue. For a properly formulated flux, the remaining flux activity posed no issue in a dried flux residue for no-clean process. However, when venting channel is blocked, not only solvents remain, but also activators could not be burnt off. The presence of solvents allows mobility of active ingredients and the associated corrosion, thus poses a major threat to the reliability. In this work, a new halogen-free no-clean SnAgCu solder paste, 33-76-1, has been developed. This solder paste exhibited SIR value above the IPC spec 100 MΩ without any dendrite formation, even with a wet flux residue on the comb pattern. The wet flux residue was caused by covering the comb pattern with 10 mm × 10 mm glass slide during reflow and SIR testing in order to mimic the poorly vented low standoff components. The paste 33-76-1 also showed very good SMT assembly performance, including voiding of QFN and HIP resistance. The wetting ability of paste 33-76-1 was very good under nitrogen. For air reflow, 33-76-1 still matched paste C which is widely accepted by industry for air reflow process. The above good performance on both non-corrosivity with wet flux residue and robust SMT process can only be accomplished through a breakthrough in flux technology.
Technical Library | 2017-01-23 21:12:01.0
"Water is not a problem of the future, but a key issue of our time for businesses: In the future, urgent water risks will increase in many areas of the world. A growing population, a changing consumer behavior and climate change will have an immediate impact on the availability and quality of water and thus build further pressure on governments, businesses and societies." (Quote from the summary of the 2014 WWF study "The imported risk. Germany's water risk in the age of globalization.")
Technical Library | 2017-07-20 15:18:15.0
As electronic devices increase functionality in smaller form factors, there will be limitations, obstacles and challenges to overcome. Advances in component technology can create issues that may have time delayed effects. One such effect is device failure due to soldering residues trapped under bottom terminated components. If the residues trapped under the component termination are active and can be mobilized with moisture, there is the potential for ion mobilization causing current leakage.
Technical Library | 2014-06-05 16:44:07.0
Stencil printing capability is becoming more important as the range of component sizes assembled on a single board increases. Coupled with increased component density, solder paste sticking to the aperture sidewalls and bottom of the stencil can cause insufficient solder paste deposits and solder bridging. Yield improvement requires increased focus on stencil technology, printer capability, solder paste functionality and understencil cleaning.(...) The purpose of this research is to study the wipe sequence, wipe frequency and wipe solvent(s) and how these factors interact to provide solder paste printing yield improvement.
Technical Library | 2017-10-26 01:18:49.0
Nano-coatings have been introduced by various manufacturers, with the promise of addressing some of the challenges relative to solder paste printing. Stated benefits include: Reduced underside cleaning, reduced bridging, improved solder paste release and improvements in yield. With several nano technologies already on the market and more likely to be introduced, how can the performance be quantified? How robust are these coatings? How can an assembler approach the ROI of these coatings? What hidden benefits or negative impacts should be considered? This paper will present a rigorous method for evaluating the performance and economic benefits of solder paste stencil nano-coatings.
Technical Library | 2023-05-22 16:42:56.0
Nano-coatings are applied to solder paste stencils with the intent of improving the solder paste printing process. Do they really make a noticeable improvement? The effect of Nano-coatings on solder paste print performance was investigated. Transfer efficiencies were studied across aperture sizes ranging from 0.30 to 0.80 area ratio. Also investigated were the effects of Nano-coatings on transfer efficiencies of tin-lead, lead-free, water soluble, no-clean, and type 3, 4, and 5 solder pastes. Solder paste print performance for each Nano-coating was summarized with respect to all of these variables.
Technical Library | 2017-03-22 20:58:08.0
Water soluble lead-free solder paste is widely used in today’s SMT processes, but the industry is slowly moving away from water soluble solder pastes in favor of no-clean solder pastes. This shift in usage of solder paste is driven by an effort to eliminate the water wash process. Some components cannot tolerate water wash and elimination of water washing streamlines the SMT process. Despite this shift, certain applications lend themselves to the use of water soluble solder paste.This paper details the research and development of a new water soluble lead-free solder paste which improves on the performance characteristics of existing technologies.
Technical Library | 2018-11-20 21:33:57.0
There are several industry-accepted methods for determining the reliability of flux residues after assembly. The recommended methods of test sample preparation do not always closely mimic the thermal cycle experienced by an assembly. Therefore, extraction from actual assemblies has become a popular method of process control to assess consistency of post-reflow cleanliness. Every method of post-reflow flux residue characterization will depend on the reflow process followed to prepare the coupon.This investigation will focus on the effect of thermal conditions on the remainder of active ingredients in flux residues after assembly with no-clean solder pastes.
Technical Library | 2019-04-18 21:53:04.0
IPX9K Rain Spray Test Chamber(high Pressure high temperature water jet) simulates the use of pressure washer steam cleaning onto the enclosure, It is recognised as the harshest of all ingress protection tests. However the requirement is becoming more prevalent across many industries. Test method for IPX9K : Make sure the water temperature inside the water tank +80°C, water flow rate with 14L-16L per min, water pressure: 8000 Kpa -10000 Kpa (80–100 bar) at distance of 100mm~ 150mm, The test duration is 30 seconds in each of 4 angles, total spray testing time is 2 minutes. IPX9 rain test chamber applicable standards: IEC 60529 – Degrees of protection provided by enclosures (IP Code).Here is working principle in picture.
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.
