The Chemical Design and Optimisation of a Non‐rosin, Water‐soluble Flux Solder Paste

Abstract Water soluble solder paste developed using T7 powder particles revealed good solderability when printed on copper, tin, gold flash nickel plated surfaces and on reflow as well. Its cross-section showed absence of voids, good wetting and soldering to the plated surfaces with angle of contact from 42° to 84° on reflow. All the solder interface are integral with pad/substrate surfaces and revealed formation of tin based intermetallics. T7 solder powder processed using Welco technology showed spherical, clean, smooth, un-agglomerated powder particles with the size range of 2 to 12μm. The developed solder paste is used for fine pitch applications.

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A thermally stable water soluble solder paste

Proceedings of IEEE 43rd Electronic Components and Technology Conference (ECTC '93) ◽

10.1109/ectc.1993.346707 ◽

2002 ◽

Author(s):

B. Carpenter ◽

K. Pearsall ◽

R. Raines ◽

R. Reich

Keyword(s):

Water Soluble ◽

Solder Paste ◽

Thermally Stable

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Preparation of PEG-rosin derivative for water soluble rosin flux

Soldering & Surface Mount Technology ◽

10.1108/ssmt-08-2015-0025 ◽

2016 ◽

Vol 28 (4) ◽

pp. 188-200 ◽

Cited By ~ 1

Author(s):

Kanlaya Phaphon ◽

Sumrit Wacharasindhu ◽

Amorn Petsom

Keyword(s):

Large Scale ◽

Gel Permeation Chromatography ◽

Water Soluble ◽

Molar Ratio ◽

Scale Production ◽

Solder Paste ◽

Scanning Calorimetry ◽

Corrosion Properties ◽

Synthetic Process ◽

Content Type

Purpose This study aims to synthesize polyethylene glycol (PEG)-rosin derivatives from rosin and PEG for the production of solid soldering fluxes. The PEG-rosin derivatives would be water soluble, and the resulting solid soldering fluxes would have reasonable wetting ability when combined with a low-halide-content activator. Design/methodology/approach This paper presents a synthetic process for PEG-rosin derivatives. The reaction conditions (including catalyst type, catalyst concentration, reaction temperature and PEG type) were optimized for the synthesis of PEG-rosin derivatives. The chemical and physical properties of PEG-rosin derivatives were characterized by Fourier transform infrared spectroscopy, carbon-13 nuclear magnetic resonance spectrometry, differential scanning calorimetry and gel permeation chromatography. The production and characteristics of water-soluble rosin fluxes (WSRFs) were studied according to the standards of the Japanese Industrial Standards (JIS) Committees. Findings WSRs were successfully synthesized from rosin and PEG using 2 per cent ZnO as a catalyst, with a 2:1 molar ratio of rosin:PEG at 250°C over 9 h. The resulting WSRs were completely soluble in water. As the PEG3000-rosin had the highest melting point (55.2°C), it was chosen for the preparation of the WSRFs. Activators such as succinic acid, glutaric acid, ethylamine hydrochloride and diethylamine hydrobromide were selected for use in the production of the fluxes. It was found that WSRF 09 and WSRF 04 gave the best performance with the lead-free Sn-0.7Cu solder alloy in terms of good solderability, low halide content (less than 1,500 ppm), high insulation resistance and low corrosion. These fluxes were applied to produce solder pastes with Sn-3.0Ag-0.5Cu alloy and they passed the performance tests as expected for solder paste. Research limitations/implications Further studies are necessary on large-scale production and to compare the performance of these fluxes to those from conventional water-soluble fluxes currently available in the market. Application of these fluxes on low-temperature solder alloys such as SnZn and SnBi (Ren et al., 2016) worth further study. Originality/value The classification of flux systems according to the JIS 3283 standard does not specify PEG-rosin derivatives in the flux; nevertheless, ranking of the flux systems based on the halide content and corrosion properties of activators would be useful information when selecting flux systems for electronics soldering in water-washable applications. The application of these fluxes in solder paste gave very promising results and is worth investigating into more detail, as well as field test.

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Achieving Low Voiding with Lead Free Solder Paste for Power Devices

International Symposium on Microelectronics ◽

10.4071/isom-2016-thp41 ◽

2016 ◽

Vol 2016 (1) ◽

pp. 000618-000623

Author(s):

Pierino I Zappella ◽

Saeed Sedehi ◽

Robert Hizon ◽

Adrienne D. Williams

Keyword(s):

Water Soluble ◽

Lead Free ◽

Power Device ◽

Solder Paste ◽

Production Environment ◽

Nickel Copper ◽

Device Applications ◽

Free Solder ◽

Silicon Device ◽

Screen Print

Abstract The objective of this research was: (1) to demonstrate a low void concentration of <5% using solder paste on different materials such as nickel to nickel, copper to copper, nickel to copper, silicon die to nickel and silicon die to copper; (2) to achieve a short cycle time for the solder paste reflow operation and (3) to highlight the advantages of solder paste vs. AuSn and other alloy preforms that require gold metallization. For power device applications where low void concentration and reduced costs are important, we have demonstrated a solder paste solution that can offer a lower cost solution. The flux incorporated in solder paste is a major contributor in creating voids. Our approach was to utilize different pressures to reduce voids resulting in higher production yields. Test coupons of pure nickel and copper were sized to simulate die and substrates. Silicon device die were also included. A lead free 95Sn5Ag alloy water soluble solder paste was selected for this evaluation. The paste application consisted of a manual screen print with templates of different thicknesses. Void detection concentrations were identified via our in-house X-ray system. The advantages of solder paste can be significant, but typically, we would expect an increase in voids resulted from the flux incorporated in the paste. Accordingly, in this paper, we evaluated a low voiding flux solder paste compatible with power device metal materials and suitable for use in a production environment.

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Water-soluble solder paste cuts out waste

Soldering & Surface Mount Technology ◽

10.1108/ssmt.2004.21916cad.006 ◽

2004 ◽

Vol 16 (3) ◽

Keyword(s):

Water Soluble ◽

Solder Paste

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Fluxes Effective in Suppressing Non-Wet-Open at BGA Assembly

International Symposium on Microelectronics ◽

10.4071/2380-4505-2018.1.000135 ◽

2018 ◽

Vol 2018 (1) ◽

pp. 000135-000139 ◽

Cited By ~ 2

Author(s):

Fengying Zhou ◽

Fen Chen ◽

Ning-Cheng Lee

Keyword(s):

Solder Bump ◽

Coefficient Of Thermal Expansion ◽

Water Soluble ◽

Solder Paste ◽

Cold Welding ◽

Barrier Method ◽

Molding Compound ◽

Long Time ◽

Medium Activity ◽

Low Activity

Abstract With the advancement in miniaturization, the die is getting thinner and the solder bump is getting smaller for BGAs. Consequently, the thermal warpage is getting more severe due to coefficient of thermal expansion mismatch between die and molding compound, and often resulted in non-wet-open (NWO) at BGA assembly. NWO has been ailing the industry for a long time, and costly rework is required to remove the problem. In this study, a “cold-welding barrier” method has been developed in suppressing NWO. At BGA assembly, after printing solder paste onto PCB, the BGA bumps are dipped into creamy flux prior to placing onto paste printed. This flux pickup will effectively suppress NWO by serving as cold-welding barrier. A low activity flux is considered having as wider reflow profile window than a medium activity flux. Alternatively, the solder bump of BGA can be pre-coated with solid flux at packaging house. The effect of solid-flux coating is equally effective in suppressing NWO. As cold welding barrier, both no-clean flux and water soluble flux are considered physically effective. However, a water soluble flux should not be used together with a no-clean solder paste based on compatibility and reliability consideration. Furthermore, only no-clean solid flux is recommended for solder bump coating purpose, mainly based on moisture pickup issue associated with water soluble flux.

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